JP2003266168A - Vertical-type casting apparatus and vertical-type casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cast product without producing a shrinkage hole, mixing oxide film and entrapping gas, particularly, the cast product having thin thickness and large size by almost perfectly exhausting the gas in a cavity and effectively pressurizing molten metal in the closed cavity. <P>SOLUTION: In a vertical type casting apparatus provided with a lower side fixed metallic mold 1 and an upper side movable metallic mold 2 which can form the cavity provided with a gas exhausting passage, an electromagnetic pump 40 and a vacuum suction means which supply and fill up the molten metal into the cavity from the lower part, a closing pin 13 which closes a molten metal flowing-in gate 10 arranged in the fixed metallic mold after the molten metal poured into the cavity fills up the cavity, and a pressurizing stem 14 and a pressurizing pin 20 which pressurize the molten metal in the cavity in the closed metallic mold, gaps for molten metal solidifying zone communicated with the gas exhausting passages are formed on the outer peripheral surfaces of the pressurizing stem and the pressurizing pin. The filled top molten metal is solidified in this gap and the gas exhausting passage can simply be closed and sealed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of casting a cast product such as an aluminum alloy having no shrinkage cavities during solidification and no gas entrainment, and filling a mold cavity with molten metal from below. In particular, the present invention relates to a rigid casting apparatus for supplying and filling molten metal into a die cavity from below by using an electromagnetic pump, and a rigid casting method using the same.

[0002]

2. Description of the Related Art When casting light alloy products and other castings, especially parts requiring high strength, a rigid die casting machine is generally used to prevent gas entrainment during casting of molten metal. Has been done. For example, as to a method of manufacturing an aluminum wheel for an automobile, as described in JP-B-3-4297, a molten metal inflow gate having a diameter smaller than a sleeve diameter for introducing the molten metal into a mold cavity, A casting method using a pressure pin having a diameter slightly smaller than the inner diameter of the gate is already known, but it is not possible to sufficiently prevent shrinkage cavities generated during solidification of the molten metal, and also to mix oxides and gas. It was not always possible to sufficiently prevent the inclusion.

Further, as described in Japanese Patent Publication No. 8-509170, it is already known to use an immersion type electromagnetic pump as a means for supplying molten metal from a molten metal holding furnace to a mold cavity. . However, the electromagnetic pump is effective for quantitatively and quickly supplying the molten metal, but simply using the electromagnetic pump can prevent shrinkage cavities that occur during solidification of the molten metal, inclusion of oxides, and entrainment of gas. It was not possible to sufficiently cope with the prevention of.

The inventor of the present invention uses a lower fixed mold, an upper movable mold and a fixed mold as a vertical casting method for preventing the inclusion of oxides and the entrainment of gas when casting general parts. The injection device is installed on the lower side, the fixed mold is provided with a vertical circular gate with a diameter smaller than the inner diameter of the casting sleeve, and the diameter of the insertion part into the circular gate is slightly smaller than the inner diameter of the circular gate. Is slidably mounted on the movable mold so that the pins can be moved up and down inside the circular gate, and the diameter of the inlet of the circular reservoir provided on the circular gate of the movable mold is jetted from the circular gate during casting. Which is larger than the diameter of the molten metal jet, and the ceiling height of the reservoir is higher than the reaching height of the molten metal jet, the molten metal is cast into the cavity of the mold, and the molten metal flows inside the cavity. Once filled, the pin protrudes to act as a feeder Proposed a method to perform (JP-1
0-146663). This method can be said to be excellent in that it is possible to prevent the inclusion of oxides, the entrapment of gas, or the shrinkage cavities that occur during solidification of the molten metal to some extent, but it sufficiently prevents the shrinkage cavities that occur during the entrainment of gas and solidification of the molten metal. I couldn't say that there was no problem at all.

The inventor of the present invention also has a lower fixed mold capable of forming a cavity having a gas discharge passage, an upper movable mold, and a vacuum for supplying and filling molten metal into the cavity from below. Suction means, a closing pin that closes the molten metal inflow gate provided in the fixed mold after the molten metal cast into the cavity is filled, and pressurization that pressurizes the molten metal in the closed mold cavity A vertical casting apparatus provided with the system and a casting method using the same were also proposed (Japanese Patent Laid-Open No. 2001-191170). This method can be said to be extremely excellent for casting products in a certain range in that it can prevent sink marks generated when oxides are mixed in, gas is entrained or molten metal is solidified, but thin and large casting products In the case of, the flow rate of the molten metal in the cavity product part becomes slow, and during the solidification of cooling, the flow velocity further decreases and the filling of the melt in the cavity product part becomes insufficient. There was a problem that a shrinkage cavity might occur because it was bad. Also, if the degree of vacuum is increased to increase the filling capacity,
There is a problem that the possibility of outside air leaking into the mold cavity increases, and the possibility of defective products occurs.

[0006]

In casting with a rigid die casting machine, in order to cast a high quality casting, particularly a thin and large casting, it is necessary to fill the mold cavity with the molten metal at a high speed. . In addition, in order to prevent oxide inclusion and gas entrapment that cause defective defects in cast products and to prevent shrinkage cavities caused by solidification shrinkage, the gas in the cavity is almost completely discharged and at the same time sufficient. It is necessary to effectively pressurize and replenish a certain amount of molten metal. At that time, it is also necessary to simplify the structure of the cavity and the structure of the entire casting apparatus for practical use in order to reduce troubles during operation. An object of the present invention is to be able to fill the mold cavity with the molten metal at a high speed, to almost completely discharge the gas in the cavity, and at the same time to effectively pressurize the molten metal in the closed cavity. It is an object of the present invention to provide a vertical casting apparatus that can easily cast a cast product that does not generate gas and does not involve gas, and a vertical casting method using the vertical casting apparatus.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies to solve the above problems, and supplies the molten metal at high speed by using an electromagnetic pump, and after the cast molten metal fills the cavity, When the molten metal is confined in the cavity by a simple means of solidifying the pre-melt in the void for the molten metal coagulation zone, and the pressure of such blocked molten metal is shortened at multiple points to effectively pressurize it, shrinkage cavities occur. The present invention has been completed by finding that it is possible to cast a cast product that is free of an oxide film and free of gas entrainment.

That is, according to the present invention, a fixed mold on the lower side and a movable mold on the upper side capable of forming a mold cavity, casting means for supplying and filling molten metal into the mold cavity from below, After the molten metal cast into the mold cavity by the pouring means fills the cavity, the closing means for closing the molten metal inflow gate provided in the fixed mold and the molten metal in the closed mold cavity are added. In a vertical casting apparatus provided with a pressurizing means for pressing, an electromagnetic pump is used as the pouring means (claim 1), or the mold cavity is provided with a gas discharge passage, The vertical casting apparatus (claim 2) according to claim 1, wherein a gap for molten metal coagulation zone communicating with the gas discharge passage is provided in the vicinity of the gas discharge passage, and the molten metal is introduced into the mold cavity. From below As a pouring means for filling, in addition to the electromagnetic pump, the gas in the die cavity is vacuum-sucked, and the molten metal is held in the molten metal holding furnace below through the pouring stalk provided on the lower side of the fixed die. A vertical casting apparatus (claim 3) according to claim 2, further comprising a vacuum suction mechanism for vacuum filling.

According to the present invention, the vertical casting apparatus according to any one of claims 1 to 3 is used to cast the molten metal into the cavity of the mold from the molten metal holding furnace through the connecting duct of the electromagnetic pump, and the molten metal is stored in the cavity. After filling, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized to cast a cast product with no shrinkage cavities during solidification and no gas entrainment. 5. The rigid casting method (claim 4) characterized by the above, and the cast product is a thin and large cast product of a light metal alloy.
The present invention relates to the rigid casting method (claim 5).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a vertical casting apparatus of the present invention,
A fixed mold on the lower side and a movable mold on the upper side capable of forming a mold cavity, pouring means for supplying and filling a molten metal into the mold cavity from below, and inside the mold cavity by the pouring means. After the molten metal cast into the cavity filled the cavity, a closing means for closing the molten metal inflow gate provided in the fixed mold and a pressurizing means for pressurizing the molten metal in the closed mold cavity were provided. In the vertical casting apparatus, it is not particularly limited as long as it is an apparatus that uses an electromagnetic pump as the pouring means, and when the vertical casting apparatus of the present invention is used, there is no occurrence of shrinkage cavities during solidification and gas winding. It is possible to favorably cast a cast product having no jam, particularly a thin and large cast product. The cast product is not particularly limited, but a light metal alloy, particularly an aluminum alloy having a large solidification shrinkage, is preferable. Since aluminum shrinks by about 7% when it solidifies, the casting apparatus and casting method of the present invention which can prevent the occurrence of shrinkage cavities are particularly thin and large in size from a molten metal made of a light metal alloy such as aluminum alloy having a large solidification shrinkage. It can be applied particularly advantageously when casting the above-mentioned casting.

The mold cavity is not particularly limited as long as the molten metal can be filled and supplied from below, but a mold cavity capable of casting a large-sized casting having a thin wall is preferable. Further, it is preferable that the mold cavity has a gas discharge passage capable of discharging the gas existing in the cavity at the time of filling the mold cavity with the molten metal and a molten metal coagulating zone void communicating with the gas discharge passage. Further, a cavity product part and a cavity hot water reservoir part are provided, and the cavity hot water reservoir part is located above the molten metal inflow gate, and a cavity hot water reservoir part of the cavity product part opposite to the cavity first hot water reservoir part. It is more preferable that it is composed of one or more cavity second hot water reservoirs located near the end portion. It is preferable that the cavity product portion and the cavity first hot water reservoir communicate with each other through a side gate, and the cavity first hot water reservoir has a larger volume than the cavity second hot water reservoir. Further, it is preferable that the gas discharge passage includes a gas discharge hole penetrating through the movable mold and a gas discharge gap or a gas discharge groove.

In the vertical casting apparatus of the present invention, an electromagnetic pump as a casting means for supplying and filling a molten metal such as molten aluminum from below in the mold cavity is installed between the molten metal holding furnace and the inflow gate. It As such an electromagnetic pump, a conventionally known immersion type electromagnetic pump can be used. For example, the immersion type electromagnetic pump described in JP-A-6-189521 or JP-A-8-215830 can be used. There are commercially available immersion type electromagnetic pumps (made by Sakai Shoji Co., Ltd.) and the like. The electromagnetic pump obtains a driving force by applying an electric current and a magnetic field to the molten metal according to Fleming's law, and enables quantitative supply of the molten metal, speeding up the supply speed and shortening the shot time lag. It enables high quality casting and casting of thin and large castings. Further, since the production cycle time is shortened by using the electromagnetic pump, the productivity is also improved. Further, the electromagnetic pump usually has a preheater and a thermocouple built therein, and can hold the molten metal at a predetermined temperature.
Generation of a solidified layer is small, and it becomes possible to suppress the occurrence of defects in a cast product due to the inclusion of the solidified layer as much as possible.

As a pouring means for supplying and filling molten metal such as molten aluminum from below in the mold cavity, in addition to the electromagnetic pump, prevention of gas entrainment during filling of the molten metal,
A vacuum suction mechanism that can be configured with a low equipment cost and a simple structure, that is, a communication duct provided adjacently below the lower fixed mold by vacuum suctioning the gas in the mold cavity ( It is more preferable to use a pouring means provided with a vacuum suction mechanism that vacuum-fills the molten metal from the lower molten metal holding furnace through a pouring stalk or sleeve). Further, the driving of the electromagnetic pump and the filling of the hot water by vacuum suction do not require a hermetically sealing the molten metal holding furnace unlike the low-pressure casting by pressurizing the molten metal surface, and the molten metal holding furnace can have any shape. By making the shape of the width narrower only around the connecting duct, the molten metal surface can be brought closer to the mold and the hot water supply can be facilitated.

Further, the lower fixed mold is formed with a communication part between the communication duct of the electromagnetic pump for casting and the cavity first molten metal reservoir part for filling and supplying the molten metal into the cavity from below. A molten metal inflow gate is provided in the communication part. The shape of the molten metal inflow gate is not particularly limited, but a circular cross-sectional shape is usually preferable in view of easiness of processing, and in this case, the inner diameter of the circular molten metal inflow gate should be smaller than the inner diameter of the communication duct. It is preferable to be configured. With this structure, the molten metal that is filled and supplied from below can be ejected into the cavity first molten metal reservoir, and as will be described later, the molten metal is poured into the communication duct that causes defective cast products. It is possible to prevent the oxide film on the surface of the molten metal and the chill layer (solidified layer) generated by cooling on the inner surface of the communication duct from being mixed into the product.

After the molten metal cast into the mold cavity by the casting means fills the cavity, the closing means in the present invention for closing the molten metal inflow gate provided in the fixed mold is the molten metal inflow. Any device may be used as long as it has a mechanism capable of closing the gate, and specific examples thereof include a closing pin arranged above the gate for opening and closing the circular molten metal inflow gate. In this case, it is preferable that the diameter of the insertion portion of the closing pin into the circular molten metal inflow gate is made slightly smaller than the inner diameter of the circular molten metal inflow gate, from the viewpoint of closed sealing. It is preferable to hold the closing pin so that it can be slidably and liquid-tightly moved in and out of the movable mold.
As will be described later, when the pressure stem is held so as to be slidable in a liquid-tight manner with respect to the movable mold, a closing pin is provided coaxially and slidably in a liquid-tight manner at the center of the pressure stem. You can also

As described above, when the pressure stem and the closing pin are arranged in the movable mold above the circular molten metal inflow gate,
Circular cavity formed in a state where these are ejected (raised) The diameter of the inlet of the first molten metal reservoir is made larger than 1.4 times the diameter of the circular molten metal inflow gate, and the pressure stem and the closing pin are ejected. It is preferable to configure the cavity first molten metal reservoir so that the height of the ceiling of the molten metal reservoir at the upper limit is 10 mm or more higher than the height of the molten metal jet ejected from the circular molten metal inflow gate described above. In this way, when the diameter of the entrance of the molten metal pool is 1.4 times the diameter of the circular gate or more, the height h of the molten metal jet is when the passing velocity of the molten metal at the circular gate is v and the acceleration of gravity is g. , H = v ² / 2g, the cavity first
For example, if the ceiling height of the molten metal pool is set to 214 mm, the jet height is h = 2.02 / 2 g≈0.204 m when the casting speed is set to a high speed of 2.0 m / sec in a general range. ,
That is, it is 204 mm, and the ceiling of the cavity first molten metal reservoir is 1 more than the height of the molten metal jet ejected from the circular molten metal inflow gate.
The height is 0 mm or more, the molten metal jet does not collide with the ceiling surface, and gas entrapment due to the collision can be prevented.

For example, although the molten metal supply / filling speed varies depending on the shape of the product, it is generally preferable that the passing speed in the circular gate is 1.0 to 2.4 m / sec, in which case the jet height from the circular gate is high. The height is usually about 50 to 300 mm, but when the height of the ceiling of the cavity first molten metal reservoir is 10 mm or more higher than the height of the molten metal jet, a free surface is formed and oxides remaining on the molten metal surface are formed. Also remains on the surface, and the gas remaining in the upper part of the molten metal pool is not confined to the downward flow, and the gas is exhausted in a vacuum from the gap around the outer periphery of the pressurizing stem, so that the gas is added to the molten metal. I will not get involved. On the other hand, if the jet speed is too slow, it will not collide with the ceiling and the gas entrainment will decrease, but the casting time will become longer, the speed at which the molten metal will flow in the cavity product will be slower, and during that time cooling and solidification will progress and the flow velocity will increase. And the filling of molten metal into the cavity product becomes insufficient,
Even if pressure is applied, the pressure transmission is poor and the possibility of shrinkage cavities increases. Therefore, it is preferable to adjust the driving force of the electromagnetic pump so that the casting speed is as high as possible,
It is preferable that the ceiling height of the cavity first hot water reservoir is high. When supplying molten metal with an electromagnetic pump, it is possible to fill the molten metal into a narrow space inside the cavity product part by its driving force, but even if filling occurs insufficiently, the pressure stem etc. There is no problem because replenishment and filling can be performed by sufficient pressurization.

By forming the cavity first molten metal reservoir in the cavity as described above, when the blocking pin or the pressure stem is advanced (lowered), the oxide or gas existing on the uppermost portion of the molten metal reservoir is used. The rolled layer stays in the cavity first molten metal reservoir without being extruded, and does not mix into the cavity product portion. Further, in the case of casting using the immersion type electromagnetic pump, as described above, the hot water inlet is below the molten metal holding furnace, and the oxide film generated on the molten metal surface floats on the molten metal surface. , Do not enter the communication duct of the electromagnetic pump.
There is a risk that the surface of the molten metal in the communication duct will be slightly oxidized by the air entering through the mold, but this small amount of oxide film will be at the tip of the jet flow and will all jump into the cavity 1st pool, It does not flow out to the cavity product portion through the gate, and the oxide is not mixed in the cast product, so that the cast product is free from defects and variations in strength.

Next, by pressurizing the molten metal filled in the closed mold cavity, it is possible to cast a cast product which does not generate shrinkage cavities during solidification and which is not entrained with gas by a jet flow. The pressurizing means for pressurizing the molten metal in the closed mold cavity is slidably provided in the movable mold above the cavity first molten metal reservoir, and the closing pin is slidable in the center thereof. The pressurizing stem provided and the cavity first hot water reservoir are slidably arranged in a movable mold above the cavity second hot water reservoir located at a position separated by a cavity product portion. The pressure pin can be specifically exemplified. It is preferable to provide a plurality of pressure pins, and the diameter thereof is preferably 2/3 to 1 times the depth of the cavity second hot water reservoir. Furthermore, it is preferable to use these pressure stems and pressure pins together. In this way, by pressurizing the molten metal from the pressure stem and the plurality of pressure pins located at distant positions, the pressure transmission distance to the molten metal in the cavity is shortened, and the pressure is evenly transmitted to the cavity product portion. Therefore, it is possible to cast a cast product that does not generate shrinkage cavities during solidification with a small pressure. As a result, it becomes possible to cast a cast product having a fine structure with a casting device with a small mold clamping force. Further, by arranging the pressure stem and the pressure pin at appropriate positions according to the form of the product, it is possible to further shorten the pressure transmission distance of the molten metal in the cavity product part and make the pressure transmission more uniform and sufficient. The generation of shrinkage cavities can be prevented with a smaller pressure.

In the conventional casting apparatus, generally, in order to cast a cast product having no shrinkage cavities at the time of solidification, the pressurization speed of the molten metal by the pressurizing means is increased and the pressurization is performed rapidly. However, in this case, the pressure transmission is too good, the mold opening force becomes large, and burrs are blown, and the mold clamping force must be increased. However, on the contrary, when the pressurizing speed is slowed, shrinkage cavities occur because the solidification shrinkage of the molten metal cannot be caught up. On the other hand, according to the present invention, it is possible to cast a cast product having no shrinkage cavity at the time of solidification with a small pressurizing pressure. Therefore, the die opening force is detected and the pressurizing speed is adjusted to a predetermined speed to perform burr blowing. Even with a small mold clamping force capable of preventing the above, uniform and sufficient pressure transmission can be performed. As described above, in the present invention, the pressurizing speed is controlled by performing program control such that the advancing speed of the pressurizing stem and the pressurizing pin at the time of pressurizing becomes a speed adapted to the solidification contraction speed of the molten metal in the cavity product portion. By adjusting it, it is possible to prevent the occurrence of shrinkage cavities while preventing burr blow with a press device with a small mold clamping force. For example, the pressing force and pressurizing speed for the molten metal during solidification shrinkage where the Pascal principle does not work. Is controlled in accordance with the solidification rate in a range where burr does not blow, so that a device with a small mold clamping force of 1/3 to 1/5 as compared with the conventional high pressure method can mix oxides and solidified layers. It is possible to obtain a cast product having a fine structure without gas entrapment.

Further, in the case of the vertical die casting method such as squeeze casting, if the pressure applied by the acurad pin (center pin) is accelerated, the casting plunger is pushed down, so that the time is delayed a little, that is, the solidification of the gate portion. As the pressure transmission to the casting plunger decreases and the pressure is applied, the molten metal in the cavity also solidifies, and a large pressure is required to replenish the molten metal. May occur. On the other hand, in the present invention, since the means for closing the molten metal inflow gate is provided, it is possible to replenish and fill the molten metal by applying pressure from a stage where the progress of solidification is still small.
Since pressure is applied by the pressure stem and a plurality of pressure pins arranged at predetermined positions, the pressure transmission distance is short and uniform and sufficient refilling can be performed with a small pressure. As a result of making the pressurizing pressure low, the mold clamping force of the mold is also small, and the cost of the mold clamping device and the mold can be kept low. Further, since the pouring speed and the pressurizing start speed are faster than those in squeeze casting, the production cycle time is shortened and the productivity is improved.

In the present invention, it is preferable that the molten metal coagulation zone void be provided near the gas discharge passage, and particularly that the molten metal solidification zone void be provided near the pressurizing means and communicate with the gas discharge passage. The molten metal coagulating zone void, for example, after the gas in the cavity is discharged from the gas discharge passage, the molten metal can be solidified in the void to be the molten metal coagulating zone, and in cooperation with the closing means, it is easy to Any kind of void can be used as long as it can seal or block the inside of the cavity. By simply providing such a void for the molten metal solidification zone, the air vent valve, the filter, etc. can be arranged and a complicated switching valve can be provided. You can easily seal and block the inside of the cavity without using a valve or
In addition, since complicated operations such as pressure adjustment are not required when the casting apparatus is operated, and further, there is no failure or the like, so the casting apparatus of the present invention can be said to be extremely practical.

Further, as the gap for the molten metal solidification zone provided in the vicinity of the pressurizing means, the pressurizing stem and / or
Alternatively, a gas discharge gap formed between the outer peripheral surface of the pressurizing pin and the inner peripheral surface of the movable mold or a gap for a molten metal solidification zone communicating with the gas discharge hole via a gas discharge groove can be exemplified. The molten metal coagulation zone void is provided concentrically with the pressure stem and / or pressure pin and has an inner diameter of 1 to 5 mm larger than the diameter of the pressure stem and / or pressure pin.
A specific example of the void is a molten metal coagulation zone having a depth (length) of about 40 mm. In this way, by making the outer diameter of each basin slightly larger than the outer diameter of the pressure stem and the pressure pin, the solidified layer generated on the outer peripheral wall of each basin is The pressure resistance of the pressure stem and the pressure pin can be reduced. Then, as described above, if the voids for the molten metal solidification zone are designed and manufactured to have a size suitable for the temperature and the casting speed of the molten metal, when the molten metal is filled, the preceding molten metal is cooled and solidified in this void portion to form a gas. It does not enter the discharge gap or the gas discharge groove.

It is preferable that the gas discharge gap and the gas discharge groove adjacent to the melt solidification zone have a size such that the preheated liquid does not flow in or a structure in which the preheated metal does not flow.
As the gas discharge gap, a gas discharge gap that is provided concentrically with the pressure stem and / or the pressure pin and has an inner diameter larger than the diameter of the pressure stem and / or the pressure pin by about 0.4 to 1.0 mm is specifically mentioned. As the gas discharge groove, a gas discharge groove extending axially on the outer peripheral surface of the pressure stem and / or the pressure pin can be specifically mentioned. And
In order to prevent air from entering when the mold cavity is evacuated, a seal packing is installed on the parting surface without providing a gas discharge hole and a gas discharge passage consisting of a gas discharge gap or a gas discharge groove. It is preferable to install the gas discharge passage at a high position of the cavity where gas easily remains, for example, above the hot water reservoir. In addition, it is preferable that seal packing is installed in all of the sliding portions of the pressure stem and the pressure pins to prevent air from leaking from the outside of the mold.

By the way, as described above, the electromagnetic pump,
For the molten metal coagulation zone provided close to the outer circumference of the pressure stem and pressure pin, if the molten metal casting speed by using the electromagnetic pump and the vacuum suction mechanism together is set to the optimum value of 1.0 to 2.4 m / sec. The air resistance in the two-stage voids such as voids and gas exhaust voids increases, but by appropriately selecting the number and arrangement of the pressure pins, it is possible to achieve the above-mentioned purpose of installing the voids for the molten metal coagulation zone and the gas exhaust voids. You can That is, a person skilled in the art can easily design a structure in which the preheated metal is cooled and solidified in the gap for the molten metal solidification zone of the two-stage void and does not enter the gas discharge void or the gas discharge groove narrower than the gap for the molten metal solidification zone. it can. In order to surely cool and solidify the preheated metal in the molten metal coagulation zone, a material with good thermal conductivity such as beryllium copper should be used for the pressure stem and pressure pin, and the structure should be water cooled. You can also

In the die casting method of the present invention, the vertical casting apparatus of the present invention is used to cast the molten metal from the molten metal holding furnace into the cavity of the mold through the connecting duct of the electromagnetic pump, and the molten metal fills the cavity. After that, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized so that there are no shrinkage cavities during solidification and no gas entrainment, preferably a light metal alloy. It is not particularly limited as long as it is a casting method for casting a large-sized thin-walled cast product, but at the retracted position of the pressure pin, filling of the molten metal into the mold cavity is started, While decelerating in the cavity second hot water reservoir and discharging the gas in the mold cavity from the gas discharge gap or the gas discharge groove, the molten metal is filled in the mold cavity by cooling and solidifying the front melt in the gap for the melt solidification zone. Was done It is preferable that one or a plurality of pressurizing pins be advanced to pressurize the molten metal in the molten metal reservoir, and the gas is discharged by vacuum degassing from the gas discharge gaps or gas discharge grooves adjacent to the plurality of molten metal solidification zones. It is preferable to further reduce the entrainment of the molten metal and to shorten the pressure transmission distance by pressurizing the molten metal with the pressure stem and the plurality of pressure pins. When the molten metal solidifies and the replenishment and filling of the molten metal is completed, the movable platen is moved up by the movable platen after a short cooling time, and the product material is lifted up along with it and the product material is moved by the pressure stem and the pressure pin and the extrusion pin. The product is extruded from the pressurizing pin, then ejected from the pressurizing pin and ejected from the pressurizing pin and the pressurizing pin, and the product material is taken out. be able to. Further, since such an operation is repeated every time, the solidified molten metal in the void for the molten metal solidification zone is removed each time, and the gas discharge passage is not clogged.

[0027]

Embodiments of the present invention will be specifically described below with reference to the drawings, but the technical scope of the present invention is not limited to these embodiments. 1 is a schematic vertical sectional view of the vertical casting apparatus of the present invention, FIG. 2 is a sectional view taken along the line AA ′ of FIG. 1, and FIG.
FIG. 4 is an explanatory view showing a sucked state of molten metal, and FIG. 4 is an explanatory view showing an operating state following FIG. 1 to 4, 1 is a fixed mold, 2 is a movable mold, 9 is a cavity product part, 10 is a circular gate, 11 is a cavity first molten metal reservoir part, 13 is a closing pin, and 14 is a pressure stem. , 17 is a void for the molten metal coagulation zone (outer periphery of the pressure stem), 19 is a cavity second hot water reservoir, 2
Reference numeral 0 is a pressure pin, 21 is a space for melt solidification zone (outer periphery of the pressure pin), 29 is a pressure stem gas discharge hole, 34 is a pressure pin gas discharge hole, 40 is an electromagnetic pump, and 41 is a communication duct.

The casting apparatus of the present invention shown in FIGS. 1 to 4 is a fixed mold 1 attached to a horizontal fixed platen 3 at the bottom of the casting apparatus, which can be moved up and down to perform mold closing. And a movable mold 2 attached to a horizontal movable platen 4 above the casting apparatus, an electromagnetic pump 40 attached below the fixed mold 1 and immersed in the molten metal 7 in the molten metal holding furnace 6, and an inflow gate. And a communication duct 41. Then, by closing the fixed mold 1 and the movable mold 2 via the seal packing 35, the cavity product part 9, the cavity first hot water reservoir 11, the cavity second hot water reservoir 19, and the cavity product. A mold cavity including a side gate 12 that communicates the portion 9 and the cavity first molten metal reservoir 11 is formed. Further, the mold is attached by moving the movable platen 4 of the mold clamping press device (not shown) in a movable state with the fixed mold 1 to which the electromagnetic pump 40 and the communication duct 41 are attached via the seal packing 38. A set of dies consisting of dies 2 is loaded, placed on the fixed platen 3, and the movable platen 4 is lowered until it comes into contact with the upper surface of the movable die 2, and the fixed die 1 is placed on the fixed platen 3 and the movable die. The mold 2 is attached to the movable platen 4 and is moved by a hydraulic cylinder having a mold clamping force that prevents the mold from opening due to the reaction force when the molten metal under pressure is supplied into the mold cavity by the driving force of the electromagnetic pump. This is done by pressing the platen 4.

In the fixed mold 1, the molten metal is connected to the connecting duct 4 by the driving force of the electromagnetic pump 40 by the action of the electromagnetic coil 39.
A circular gate 10 for discharging the molten metal from the mold 1, sucking the molten metal by evacuating the mold cavity, and ejecting the molten metal tip.
Is provided. When the electromagnetic pump 40 is driven and the inside of the cavity is depressurized, the molten metal 7 in the molten metal holding furnace 6 is pushed up into the communication duct 41 by the pressure difference between the driving force of the electromagnetic pump 40 and the atmospheric pressure, and the fixed mold is formed. Circular gate 1
It is filled in the cavity product part 9 through 0. The pouring speed at this time is controlled by adjusting the driving force of the electromagnetic pump and the degree of vacuum in the cavity so that the molten metal passes through the circular gate 10 quickly and becomes a jet flow and is jetted upward. In addition, as shown in FIG.
The inlet diameter d ₁ of the hot water reservoir 11 is configured to be 1.4 times or more the diameter d of the circular gate 10, and the outer diameter d of the pressurizing stem 14 is set.
s is configured to be slightly smaller than the inlet diameter d _{1 of the} hot water reservoir 11, and the ceiling height of the first cavity hot water reservoir 11 is given by the formula: h = v ² / 2g (where h is the jet arrival height) , V is the circular gate passage speed, and g is the acceleration of gravity.) The height is higher than the height h reached by the molten metal jet 15 passing through the circular gate 10. Therefore, in the initial stage of filling, the jet flow does not collide with the ceiling of the cavity first molten metal reservoir 11, a free surface of the molten metal jet 15 is formed on the upper portion thereof, and the descending flow of this portion disappears, so that the molten metal surface Oxide remains stationary and pool 1
As a result of eliminating the gas remaining in the upper part of No. 1 from getting into the molten metal 16, the molten metal jet flow 1 passing through these circular gates 1
The slight oxide film and solidified layer at the tip of 5 all remain in the cavity first molten metal reservoir 11, and only clean molten metal without entrapment of oxide or gas passes through the side gate 12 and the cavity product portion 9 Will be filled inside.

A hydraulic cylinder 25 is liquid-tightly disposed in the movable mold 2 above the circular gate 10 via a seal packing 27, and the pressurizing stem 14 is hydraulically attached to the hydraulic cylinder 25 by the cavity first. A pressurizing stem piston 23 capable of advancing and retracting to and from the hot water reservoir 11 is housed via a seal packing 27, and the pressurizing stem piston 23 is provided with a closing pin 13 capable of closing the circular gate 10. A closing pin piston 24 that can be advanced and retracted is accommodated coaxially with the pressure stem piston 23. After the mold cavity is filled with molten metal,
The closing pin 13 is moved forward by the piston 24 to close the circular gate 10, and immediately thereafter, the pressure stem 14 is moved forward by the piston 23, and the volume of the unfilled void in the cavity product portion 9 and the molten metal corresponding to the solidification shrinkage volume are melted. Pressure is supplied from the cavity first hot water reservoir 11. At this time, since the stalk of the pressure stem 14 is large, a sufficient amount of molten metal can be replenished and pressure-filled.

Even during pressurization by the pressurizing stem 14, a slight amount of oxide is generated on the molten metal surface in the communication duct 41 of the electromagnetic pump 40, and the solidification of the surface of the molten metal formed by cooling at the inlet of the circular gate 10 The gas entrained layer generated by the layer or the jet flow gathers at the uppermost part of the hot water reservoir 11 by the gate jet flow 15, remains in the cavity first hot water reservoir 11 without being extruded by the pressure stem 14, and the cavity product portion 9 As a result, there are no casting defects caused by these. Further, on the outer periphery of the pressurizing stem 14, there is provided a two-stage space including a gas discharge space 18 communicating with the gas discharge hole 29 and a melt solidification zone space 17. As shown in FIG. 4d, the gas discharge void 18 is secured every time the casting is performed because the solidified layer formed in the molten metal solidification zone void 17 is taken out together with the product material.

Further, one or two or more small cavity second hot water reservoirs 19 are formed above the ends of the cavity product portion 9, and the movable mold 2 above the hot water reservoir 19 is provided with: A hydraulic cylinder 31 is provided, and the hydraulic cylinder 31 accommodates a pressure pin piston 30 that can move the two pressure pins 20 back and forth to and from the cavity second hot water reservoir 19. The one or more pressing pins 20 have an axis in a direction parallel to the mold opening / closing direction and orthogonal to the mold parting surface, and are liquid-tightly provided to the movable mold 2 via the seal packing 33. . Also on the outer circumference of these pressurizing pins 20, there are provided two-stage voids, which are a gas exhaust void 22 communicating with the gas exhaust hole 34 and a molten metal solidification zone void 21. Then, after replenishing and filling the inside of the cavity product portion 9 with the pressure stem 14, these pressure pins 20 are pushed out to pressurize the molten metal of the cavity product portion 9 through the cavity second molten metal reservoir portion 19. ing. Further, the outer diameter of the pressurizing pin 20 is configured to be slightly smaller than the diameter of the inlet of the cavity second hot water reservoir 19. Since these pressurizing pins 20 also slide every time, the solidified layer formed in the molten metal solidification zone voids 21 is extruded by an extruding pin (not shown) in a state of being attached to the product material and does not remain in the gas passage holes, and the gas discharge passage Is being secured.

Next, the operation will be described. After mold clamping is completed,
The molten metal 16 is sucked up into the cavity first molten metal reservoir 11 by the driving force of the electromagnetic pump 40 and the vacuum suction force into the cavity. The molten metal 16 rises in the communication duct 41, passes through the circular gate 10 of the fixed mold 1 and is ejected (FIG. 3), and then is filled in the cavity product portion 9. Generally, since there is a flow resistance in the cavity product portion 9, before the molten metal reaches the cavity second molten metal reservoir portion 19 below the pressurizing pin, the cavity first molten metal reservoir portion 11 above the circular gate 10 is provided. Is filled with the molten metal (Fig. 4a), but when the preceding molten metal enters the two-stage voids 17 and 21 for the molten metal coagulation zone, the passage is narrow, the heat capacity of the molten metal is small, and conversely the cooling area is large. Since the cooling rate is high, the solidification progresses, and the fluidity decreases, the tip of the molten metal does not stop in the middle of the gap 17 for the molten metal solidification zone and does not solidify and enter the gas discharge void 18.

When the flow of the molten metal in the cavity is stopped, it is detected as a signal indicating the completion of filling, and the closing pin 13 is immediately advanced to insert and close the circular gate 10 (FIG. 4b). In this way, after the molten metal in the cavity product portion 9 and the cavity first molten metal portion 11 is blocked so as not to flow back into the communication duct 41, the pressure stem 14 is immediately advanced to pressurize the molten metal in the cavity first molten metal portion 11. The molten metal in the semi-solidified state is refilled into the cavity product portion 9 (FIG. 4c). When the filling is completed and cooling is started, solidification shrinkage of the molten metal 16 occurs. Therefore, high pressure is applied to the pressurizing stem 14 to advance it, and replenishment is performed according to the solidification shrinkage volume. Circular gate 1 with blocking pin 13
Even if the contact between the closing pin 13 and the circular gate 10 is not perfect at the time of 0 closing, the molten metal existing in the small voids quickly cools and solidifies, and the molten metal flows from the circular gate 10 into the communication duct 4
1, the molten metal in the gate 10 and the communication duct 41 cannot rise, and the current is flown back to the electromagnetic coil 39, so that the communication duct 41
A downward force is applied to the remaining molten metal and the material is dropped into a holding furnace.

In the case of replenishment and filling by the pressure stem 14, the resistance is small, the force of the pressure cylinder of the pressure stem 14 is small, and the hydraulic pressure in the hydraulic cylinder can be advanced in a low state. By the refilling and filling by the advance of the pressure stem 14, the molten pin refills and fills the cavity product part 9 and the cavity second hot water reservoir part 19, and then the pressurizing pin 20 is advanced. The pressurization by the pressurizing pin 20 is started by detecting the fact that the flow resistance increases and the hydraulic pressure rises with the completion of the filling by the pressurizing stem 14. Replenishment according to the solidification shrinkage volume due to the advancing of the pressure stem 14 is difficult to transmit pressure up to the opposite end of the cavity product portion 9. Therefore, the pressurizing pin 20 around the end is actuated to pressurize the entire surface. As a result, it is possible to obtain a densely structured product without shrinkage cavities due to coagulation and condensation. After the cooling and solidification of the molten metal in the cavity product portion 9 is completed, the mold material is opened and the product material lifted by the movable mold can be extruded and taken out by the pressure pins and the extruding pins (FIG. 4).
d).

[0036]

When the casting apparatus of the present invention is used, the structure of the gas discharge system around the pressure stem and the pressure pin is simple, and troubles during operation are reduced. Also, by using an electromagnetic pump and a vacuum suction mechanism to fill the mold cavity with the molten metal at high speed, the molten metal precursor flows into the narrow gap for the molten metal solidification zone, where it solidifies and stops there. Never infiltrate. Also, by making the depth of the cavity first molten metal reservoir deeper, the stroke of the pressure stem can be lengthened, and a sufficient volume of molten metal for replenishment filling and solidification contraction in the cavity product portion can be obtained. By press-fitting, it is possible to obtain a cast product having a finer structure and strength. In addition, by closing the circular gate with a blocking pin slightly smaller than the inner diameter of the circular gate, and causing the current to flow backwards through the electromagnetic coil, the molten metal in the communication duct can be quickly returned to the holding furnace and the product can be taken out easily. be able to.

Further, in the casting apparatus of the present invention equipped with the electromagnetic pump and the vacuum suction mechanism, when the mold cavity is filled with the molten metal, the gas in the cavity is almost completely discharged, and at the same time, the circular gate is opened after the filling. Since it can be closed and the necessary and sufficient pressure can be applied with a small pressure, it can be
A mold clamping force of ⅓ to ⅕ can be used, the cost of the casting apparatus can be significantly reduced, and the cost of the cast product can be significantly reduced. In addition, since the molten metal is directly supplied from the holding furnace, no oxide is generated, and the passage is short, so that the solidified layer is less likely to be generated, and the cavity first molten metal part having an appropriate height at the outlet of the circular gate. Since the jet flow does not collide with the ceiling, the gas entrainment can be eliminated, and a small amount of oxide or solidified layer that remains may be retained in the cavity first molten metal reservoir, resulting in a dense structure with no impurities. It is possible to obtain a cast product having a different structure. Furthermore, unlike the low pressure casting, the molten metal holding furnace is not closed, so it is easy to replenish the molten metal and not only the equipment cost is low, but also the arrangement and operation of the equipment such as raising the molten metal surface and shortening the communication duct are possible. It will be easier.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a vertical casting apparatus of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is an explanatory diagram showing a suction state of molten metal in the vertical casting apparatus of the present invention.

FIG. 4 is an explanatory view showing an operating state in the vertical casting apparatus of the present invention following FIG.

[Explanation of symbols]

1 Fixed mold 2 movable mold 3 Fixed platen 4 movable platen 6 Molten metal holding furnace 7,16 molten metal 8 Hot water surface 9 Mold cavity 10 round gate 11 Cavity 1st hot water reservoir 12 side gates 13 Blocking pin 14 Pressure stem 15 jets 17 Pressurized stem molten metal coagulation zone void 18 Pressurized stem gas discharge space 19 Cavity No. 2 hot water reservoir 20 pressure pin 21 Pressurizing Pin Void for molten metal coagulation zone 22 Gas discharge space around pressurizing pin 23 Piston for pressure stem 24 Piston for closing pin 25 hydraulic cylinder 26 Pressure oil inlet a, b, c 27 Pressure stem Seal packing 28 Blocking pin Seal packing 29 Pressure stem Discharge passage 30 Pressure pin Piston 31 Pressure pin Hydraulic cylinder 32 Pressure oil inlet 33 Pressure pin Seal packing 34 Pressurizing pin Gas discharge passage 35 mold seal packing 36 Pressure stem cooling water hole 37 Pressure pin cooling water hole 39 electromagnetic coil 40 electromagnetic pump 41 Communication duct

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[Procedure amendment]

[Submission date] April 11, 2002 (2002.4.1)
1)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Vertical casting apparatus and vertical casting method

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of casting a cast product such as an aluminum alloy having no shrinkage cavities during solidification and no gas entrainment, and filling a mold cavity with molten metal from below. in particular to vertical casting method using vertical casting apparatus and it is supplied filled with molten metal from below into the mold cavity by using an electromagnetic pump.

[0002]

2. Description of the Related Art A vertical die casting machine is generally used to prevent gas entrainment during casting of molten metal when casting light alloy products and the like, especially parts requiring high strength. Has been done. For example, as to a method of manufacturing an aluminum wheel for an automobile, as described in JP-B-3-4297, a molten metal inflow gate having a diameter smaller than a sleeve diameter for introducing the molten metal into a mold cavity, A casting method using a pressure pin having a diameter slightly smaller than the inner diameter of the gate is already known, but it is not possible to sufficiently prevent shrinkage cavities generated during solidification of the molten metal, and also to mix oxides and gas. It was not always possible to sufficiently prevent the inclusion.

Further, as described in Japanese Patent Publication No. 8-509170, it is already known to use an immersion type electromagnetic pump as a means for supplying molten metal from a molten metal holding furnace to a mold cavity. . However, the electromagnetic pump is effective for quantitatively and quickly supplying the molten metal, but simply using the electromagnetic pump can prevent shrinkage cavities that occur during solidification of the molten metal, inclusion of oxides, and entrainment of gas. It was not possible to sufficiently cope with the prevention of.

The inventor of the present invention uses a lower fixed mold, an upper movable mold and a fixed mold as a vertical casting method for preventing the inclusion of oxides and the entrainment of gas when casting general parts. The injection device is installed on the lower side, the fixed mold is provided with a vertical circular gate with a diameter smaller than the inner diameter of the casting sleeve, and the diameter of the insertion part into the circular gate is slightly smaller than the inner diameter of the circular gate. Is slidably mounted on the movable mold so that the pins can be moved up and down inside the circular gate, and the diameter of the inlet of the circular reservoir provided on the circular gate of the movable mold is jetted from the circular gate during casting. greater than the diameter of the melt jet is, using a vertical casting apparatus ceiling height higher than reach the height of the melt jet reservoir, pouring the molten metal into the mold cavity, the molten metal in the cavity Once filled, the pin protrudes to act as a feeder Proposed a method to perform (JP-1
0-146663). This method can be said to be excellent in that it is possible to prevent the inclusion of oxides, the entrapment of gas, or the shrinkage cavities that occur during solidification of the molten metal to some extent, but it sufficiently prevents the shrinkage cavities that occur during the entrainment of gas and solidification of the molten metal. I couldn't say that there was no problem at all.

The inventor of the present invention also has a lower fixed mold capable of forming a cavity having a gas discharge passage, an upper movable mold, and a vacuum for supplying and filling molten metal into the cavity from below. Suction means, a closing pin that closes the molten metal inflow gate provided in the fixed mold after the molten metal cast into the cavity is filled, and pressurization that pressurizes the molten metal in the closed mold cavity A vertical casting apparatus provided with the system and a casting method using the same were also proposed (Japanese Patent Laid-Open No. 2001-191170). This method can be said to be extremely excellent for casting products in a certain range in that it can prevent sink marks generated when oxides are mixed in, gas is entrained or molten metal is solidified, but thin and large casting products In the case of, the flow rate of the molten metal in the cavity product part becomes slow, and during the solidification of cooling, the flow velocity further decreases and the filling of the melt in the cavity product part becomes insufficient. There was a problem that a shrinkage cavity might occur because it was bad. Also, if the degree of vacuum is increased to increase the filling capacity,
There is a problem that the possibility of outside air leaking into the mold cavity increases, and the possibility of defective products occurs.

[0006]

In casting with a vertical die casting machine, in order to cast a high quality casting, particularly a thin and large casting, it is necessary to fill the mold cavity with the molten metal at a high speed. .. In addition, in order to prevent oxide inclusion and gas entrapment that cause defective defects in cast products and to prevent shrinkage cavities caused by solidification shrinkage, the gas in the cavity is almost completely discharged and at the same time sufficient. It is necessary to effectively pressurize and replenish a certain amount of molten metal. At that time, it is also necessary to simplify the structure of the cavity and the structure of the entire casting apparatus for practical use in order to reduce troubles during operation. An object of the present invention is to be able to fill the mold cavity with the molten metal at a high speed, to almost completely discharge the gas in the cavity, and at the same time to effectively pressurize the molten metal in the closed cavity. It is an object of the present invention to provide a vertical casting apparatus that can easily cast a cast product that does not generate gas and does not involve gas, and a vertical casting method using the vertical casting apparatus.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies to solve the above problems, and supplies the molten metal at high speed by using an electromagnetic pump, and after the cast molten metal fills the cavity, When the molten metal is confined in the cavity by a simple means of solidifying the pre-melt in the void for the molten metal coagulation zone, and the pressure of such blocked molten metal is shortened at multiple points to effectively pressurize it, shrinkage cavities occur. The present invention has been completed by finding that it is possible to cast a cast product that is free of an oxide film and free of gas entrainment.

That is, according to the present invention, a fixed mold on the lower side and a movable mold on the upper side capable of forming a mold cavity, casting means for supplying and filling molten metal into the mold cavity from below, After the molten metal cast into the mold cavity by the pouring means fills the cavity, the closing means for closing the molten metal inflow gate provided in the fixed mold and the molten metal in the closed mold cavity are added. In a vertical casting apparatus provided with a pressurizing means for pressing, an electromagnetic pump is used as the pouring means (claim 1), or the mold cavity is provided with a gas discharge passage, The vertical casting apparatus (claim 2) according to claim 1, wherein a gap for molten metal coagulation zone communicating with the gas discharge passage is provided in the vicinity of the gas discharge passage, and the molten metal is introduced into the mold cavity. From below As a pouring means for filling, in addition to the electromagnetic pump, the gas in the die cavity is vacuum-sucked, and the molten metal is held in the molten metal holding furnace below through the pouring stalk provided on the lower side of the fixed die. A vertical casting apparatus (claim 3) according to claim 2, further comprising a vacuum suction mechanism for vacuum filling.

According to the present invention, the vertical casting apparatus according to any one of claims 1 to 3 is used to cast the molten metal into the cavity of the mold from the molten metal holding furnace through the connecting duct of the electromagnetic pump, and the molten metal is stored in the cavity. After filling, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized to cast a cast product with no shrinkage cavities during solidification and no gas entrainment. The vertical casting method (claim 4) characterized by the above, or the cast product is a thin and large cast product of a light metal alloy.
The present invention relates to the vertical casting method (claim 5).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a vertical casting apparatus of the present invention,
A fixed mold on the lower side and a movable mold on the upper side capable of forming a mold cavity, pouring means for supplying and filling a molten metal into the mold cavity from below, and inside the mold cavity by the pouring means. After the molten metal cast into the cavity filled the cavity, a closing means for closing the molten metal inflow gate provided in the fixed mold and a pressurizing means for pressurizing the molten metal in the closed mold cavity were provided. In the vertical casting apparatus, it is not particularly limited as long as it is an apparatus that uses an electromagnetic pump as the pouring means, and when the vertical casting apparatus of the present invention is used, there is no occurrence of shrinkage cavities during solidification and gas winding. It is possible to favorably cast a cast product having no jam, particularly a thin and large cast product. The cast product is not particularly limited, but a light metal alloy, particularly an aluminum alloy having a large solidification shrinkage, is preferable. Since aluminum shrinks by about 7% when it solidifies, the casting apparatus and casting method of the present invention which can prevent the occurrence of shrinkage cavities are particularly thin and large in size from a molten metal made of a light metal alloy such as aluminum alloy having a large solidification shrinkage. It can be applied particularly advantageously when casting the above-mentioned casting.

The mold cavity is not particularly limited as long as the molten metal can be filled and supplied from below, but a mold cavity capable of casting a large-sized casting having a thin wall is preferable. Further, it is preferable that the mold cavity has a gas discharge passage capable of discharging the gas existing in the cavity at the time of filling the mold cavity with the molten metal and a molten metal coagulating zone void communicating with the gas discharge passage. Further, a cavity product part and a cavity hot water reservoir part are provided, and the cavity hot water reservoir part is located above the molten metal inflow gate, and a cavity hot water reservoir part of the cavity product part opposite to the cavity first hot water reservoir part. It is more preferable that it is composed of one or more cavity second hot water reservoirs located near the end portion. It is preferable that the cavity product portion and the cavity first hot water reservoir communicate with each other through a side gate, and the cavity first hot water reservoir has a larger volume than the cavity second hot water reservoir. Further, it is preferable that the gas discharge passage includes a gas discharge hole penetrating through the movable mold and a gas discharge gap or a gas discharge groove.

In the vertical casting apparatus of the present invention, an electromagnetic pump as a casting means for supplying and filling a molten metal such as molten aluminum from below in the mold cavity is installed between the molten metal holding furnace and the inflow gate. It As such an electromagnetic pump, a conventionally known immersion type electromagnetic pump can be used. For example, the immersion type electromagnetic pump described in JP-A-6-189521 or JP-A-8-215830 can be used. There are commercially available immersion type electromagnetic pumps (made by Sakai Shoji Co., Ltd.) and the like. The electromagnetic pump obtains a driving force by applying an electric current and a magnetic field to the molten metal according to Fleming's law, and enables quantitative supply of the molten metal, speeding up the supply speed and shortening the shot time lag. It enables high quality casting and casting of thin and large castings. Further, since the production cycle time is shortened by using the electromagnetic pump, the productivity is also improved. Further, the electromagnetic pump usually has a preheater and a thermocouple built therein, and can hold the molten metal at a predetermined temperature.
Generation of a solidified layer is small, and it becomes possible to suppress the occurrence of defects in a cast product due to the inclusion of the solidified layer as much as possible.

As a pouring means for supplying and filling molten metal such as molten aluminum from below in the mold cavity, in addition to the electromagnetic pump, prevention of gas entrainment during filling of the molten metal,
A vacuum suction mechanism that can be configured with a low equipment cost and a simple structure, that is, a communication duct provided adjacently below the lower fixed mold by vacuum suctioning the gas in the mold cavity ( It is more preferable to use a pouring means provided with a vacuum suction mechanism that vacuum-fills the molten metal from the lower molten metal holding furnace through a pouring stalk or sleeve). Further, the driving of the electromagnetic pump and the filling of the hot water by vacuum suction do not require a hermetically sealing the molten metal holding furnace unlike the low-pressure casting by pressurizing the molten metal surface, and the molten metal holding furnace can have any shape. By making the shape of the width narrower only around the connecting duct, the molten metal surface can be brought closer to the mold and the hot water supply can be facilitated.

Further, the lower fixed mold is formed with a communication part between the communication duct of the electromagnetic pump for casting and the cavity first molten metal reservoir part for filling and supplying the molten metal into the cavity from below. A molten metal inflow gate is provided in the communication part. The shape of the molten metal inflow gate is not particularly limited, but a circular cross-sectional shape is usually preferable in view of easiness of processing, and in this case, the inner diameter of the circular molten metal inflow gate should be smaller than the inner diameter of the communication duct. It is preferable to be configured. With this structure, the molten metal that is filled and supplied from below can be ejected into the cavity first molten metal reservoir, and as will be described later, the molten metal is poured into the communication duct that causes defective cast products. It is possible to prevent the oxide film on the surface of the molten metal and the chill layer (solidified layer) generated by cooling on the inner surface of the communication duct from being mixed into the product.

After the molten metal cast into the mold cavity by the casting means fills the cavity, the closing means in the present invention for closing the molten metal inflow gate provided in the fixed mold is the molten metal inflow. Any device may be used as long as it has a mechanism capable of closing the gate, and specific examples thereof include a closing pin arranged above the gate for opening and closing the circular molten metal inflow gate. In this case, it is preferable that the diameter of the insertion portion of the closing pin into the circular molten metal inflow gate is made slightly smaller than the inner diameter of the circular molten metal inflow gate, from the viewpoint of closed sealing. It is preferable to hold the closing pin so that it can be slidably and liquid-tightly moved in and out of the movable mold.
As will be described later, when the pressure stem is held so as to be slidable in a liquid-tight manner with respect to the movable mold, a closing pin is provided coaxially and slidably in a liquid-tight manner at the center of the pressure stem. You can also

As described above, when the pressure stem and the closing pin are arranged in the movable mold above the circular molten metal inflow gate,
Circular cavity formed in a state where these are ejected (raised) The diameter of the inlet of the first molten metal reservoir is made larger than 1.4 times the diameter of the circular molten metal inflow gate, and the pressure stem and the closing pin are ejected. It is preferable to configure the cavity first molten metal reservoir so that the height of the ceiling of the molten metal reservoir at the upper limit is 10 mm or more higher than the height of the molten metal jet ejected from the circular molten metal inflow gate described above. In this way, when the diameter of the entrance of the molten metal pool is 1.4 times the diameter of the circular gate or more, the height h of the molten metal jet is when the passing velocity of the molten metal at the circular gate is v and the acceleration of gravity is g. , H = v ² / 2g, the cavity first
For example, if the ceiling height of the molten metal pool is set to 214 mm, the jet height is h = 2.02 / 2 g≈0.204 m when the casting speed is set to a high speed of 2.0 m / sec in a general range. ,
That is, it is 204 mm, and the ceiling of the cavity first molten metal reservoir is 1 more than the height of the molten metal jet ejected from the circular molten metal inflow gate.
The height is 0 mm or more, the molten metal jet does not collide with the ceiling surface, and gas entrapment due to the collision can be prevented.

For example, although the molten metal supply / filling speed varies depending on the shape of the product, it is generally preferable that the passing speed in the circular gate is 1.0 to 2.4 m / sec, in which case the jet height from the circular gate is high. The height is usually about 50 to 300 mm, but when the height of the ceiling of the cavity first molten metal reservoir is 10 mm or more higher than the height of the molten metal jet, a free surface is formed and oxides remaining on the molten metal surface are formed. Also remains on the surface, and the gas remaining in the upper part of the molten metal pool is not confined to the downward flow, and the gas is exhausted in a vacuum from the gap around the outer periphery of the pressurizing stem, so that the gas is added to the molten metal. I will not get involved. On the other hand, if the jet speed is too slow, it will not collide with the ceiling and the gas entrainment will decrease, but the casting time will become longer, the speed at which the molten metal will flow in the cavity product will be slower, and during that time cooling and solidification will progress and the flow velocity will increase. And the filling of molten metal into the cavity product becomes insufficient,
Even if pressure is applied, the pressure transmission is poor and the possibility of shrinkage cavities increases. Therefore, it is preferable to adjust the driving force of the electromagnetic pump so that the casting speed is as high as possible,
It is preferable that the ceiling height of the cavity first hot water reservoir is high. When supplying molten metal with an electromagnetic pump, it is possible to fill the molten metal into a narrow space inside the cavity product part by its driving force, but even if filling occurs insufficiently, the pressure stem etc. There is no problem because replenishment and filling can be performed by sufficient pressurization.

By forming the cavity first molten metal reservoir in the cavity as described above, when the blocking pin or the pressure stem is advanced (lowered), the oxide or gas existing on the uppermost portion of the molten metal reservoir is used. The rolled layer stays in the cavity first molten metal reservoir without being extruded, and does not mix into the cavity product portion. Further, in the case of casting using the immersion type electromagnetic pump, as described above, the hot water inlet is below the molten metal holding furnace, and the oxide film generated on the molten metal surface floats on the molten metal surface. , Do not enter the communication duct of the electromagnetic pump.
There is a risk that the surface of the molten metal in the communication duct will be slightly oxidized by the air entering through the mold, but this small amount of oxide film will be at the tip of the jet flow and will all jump into the cavity 1st pool, It does not flow out to the cavity product portion through the gate, and the oxide is not mixed in the cast product, so that the cast product is free from defects and variations in strength.

Next, by pressurizing the molten metal filled in the closed mold cavity, it is possible to cast a cast product which does not generate shrinkage cavities during solidification and which is not entrained with gas by a jet flow. The pressurizing means for pressurizing the molten metal in the closed mold cavity is slidably provided in the movable mold above the cavity first molten metal reservoir, and the closing pin is slidable in the center thereof. The pressurizing stem provided and the cavity first hot water reservoir are slidably arranged in a movable mold above the cavity second hot water reservoir located at a position separated by a cavity product portion. The pressure pin can be specifically exemplified. It is preferable to provide a plurality of pressure pins, and the diameter thereof is preferably 2/3 to 1 times the depth of the cavity second hot water reservoir. Furthermore, it is preferable to use these pressure stems and pressure pins together. In this way, by pressurizing the molten metal from the pressure stem and the plurality of pressure pins located at distant positions, the pressure transmission distance to the molten metal in the cavity is shortened, and the pressure is evenly transmitted to the cavity product portion. Therefore, it is possible to cast a cast product that does not generate shrinkage cavities during solidification with a small pressure. As a result, it becomes possible to cast a cast product having a fine structure with a casting device with a small mold clamping force. Further, by arranging the pressure stem and the pressure pin at appropriate positions according to the form of the product, it is possible to further shorten the pressure transmission distance of the molten metal in the cavity product part and make the pressure transmission more uniform and sufficient. The generation of shrinkage cavities can be prevented with a smaller pressure.

In the conventional casting apparatus, generally, in order to cast a cast product having no shrinkage cavities at the time of solidification, the pressurization speed of the molten metal by the pressurizing means is increased and the pressurization is performed rapidly. However, in this case, the pressure transmission is too good, the mold opening force becomes large, and burrs are blown, and the mold clamping force must be increased. However, on the contrary, when the pressurizing speed is slowed, shrinkage cavities occur because the solidification shrinkage of the molten metal cannot be caught up. On the other hand, according to the present invention, it is possible to cast a cast product having no shrinkage cavity at the time of solidification with a small pressurizing pressure. Therefore, the die opening force is detected and the pressurizing speed is adjusted to a predetermined speed to perform burr blowing. Even with a small mold clamping force capable of preventing the above, uniform and sufficient pressure transmission can be performed. As described above, in the present invention, the pressurizing speed is controlled by performing program control such that the advancing speed of the pressurizing stem and the pressurizing pin at the time of pressurizing becomes a speed adapted to the solidification contraction speed of the molten metal in the cavity product portion. By adjusting it, it is possible to prevent the occurrence of shrinkage cavities while preventing burr blow with a press device with a small mold clamping force. For example, the pressing force and pressurizing speed for the molten metal during solidification shrinkage where the Pascal principle does not work. Is controlled in accordance with the solidification rate in a range where burr does not blow, so that a device with a small mold clamping force of 1/3 to 1/5 as compared with the conventional high pressure method can mix oxides and solidified layers. It is possible to obtain a cast product having a fine structure without gas entrapment.

Further, in the case of the vertical die casting method such as squeeze casting, if the pressure applied by the acurad pin (center pin) is accelerated, the casting plunger is pushed down, so that the time is delayed a little, that is, the solidification of the gate portion. As the pressure transmission to the casting plunger decreases and the pressure is applied, the molten metal in the cavity also solidifies, and a large pressure is required to replenish the molten metal. May occur. On the other hand, in the present invention, since the means for closing the molten metal inflow gate is provided, it is possible to replenish and fill the molten metal by applying pressure from a stage where the progress of solidification is still small.
Since pressure is applied by the pressure stem and a plurality of pressure pins arranged at predetermined positions, the pressure transmission distance is short and uniform and sufficient refilling can be performed with a small pressure. As a result of making the pressurizing pressure low, the mold clamping force of the mold is also small, and the cost of the mold clamping device and the mold can be kept low. Further, since the pouring speed and the pressurizing start speed are faster than those in squeeze casting, the production cycle time is shortened and the productivity is improved.

In the present invention, it is preferable that the molten metal coagulation zone void be provided near the gas discharge passage, and particularly that the molten metal solidification zone void be provided near the pressurizing means and communicate with the gas discharge passage. The molten metal coagulating zone void, for example, after the gas in the cavity is discharged from the gas discharge passage, the molten metal can be solidified in the void to be the molten metal coagulating zone, and in cooperation with the closing means, it is easy to Any kind of void can be used as long as it can seal or block the inside of the cavity. By simply providing such a void for the molten metal solidification zone, the air vent valve, the filter, etc. can be arranged and a complicated switching valve can be provided. You can easily seal and block the inside of the cavity without using a valve or
In addition, since complicated operations such as pressure adjustment are not required when the casting apparatus is operated, and further, there is no failure or the like, so the casting apparatus of the present invention can be said to be extremely practical.

Further, as the gap for the molten metal solidification zone provided in the vicinity of the pressurizing means, the pressurizing stem and / or
Alternatively, a gas discharge gap formed between the outer peripheral surface of the pressurizing pin and the inner peripheral surface of the movable mold or a gap for a molten metal solidification zone communicating with the gas discharge hole via a gas discharge groove can be exemplified. The molten metal coagulation zone void is provided concentrically with the pressure stem and / or pressure pin and has an inner diameter of 1 to 5 mm larger than the diameter of the pressure stem and / or pressure pin.
A specific example of the void is a molten metal coagulation zone having a depth (length) of about 40 mm. In this way, by making the outer diameter of each basin slightly larger than the outer diameter of the pressure stem and the pressure pin, the solidified layer generated on the outer peripheral wall of each basin is The pressure resistance of the pressure stem and the pressure pin can be reduced. Then, as described above, if the voids for the molten metal solidification zone are designed and manufactured to have a size suitable for the temperature and the casting speed of the molten metal, when the molten metal is filled, the preceding molten metal is cooled and solidified in this void portion to form a gas. It does not enter the discharge gap or the gas discharge groove.

It is preferable that the gas discharge gap and the gas discharge groove adjacent to the melt solidification zone have a size such that the preheated liquid does not flow in or a structure in which the preheated metal does not flow.
As the gas discharge gap, a gas discharge gap that is provided concentrically with the pressure stem and / or the pressure pin and has an inner diameter larger than the diameter of the pressure stem and / or the pressure pin by about 0.4 to 1.0 mm is specifically mentioned. As the gas discharge groove, a gas discharge groove extending axially on the outer peripheral surface of the pressure stem and / or the pressure pin can be specifically mentioned. And
In order to prevent air from entering when the mold cavity is evacuated, a seal packing is installed on the parting surface without providing a gas discharge hole and a gas discharge passage consisting of a gas discharge gap or a gas discharge groove. It is preferable to install the gas discharge passage at a high position of the cavity where gas easily remains, for example, above the hot water reservoir. In addition, it is preferable that seal packing is installed in all of the sliding portions of the pressure stem and the pressure pins to prevent air from leaking from the outside of the mold.

By the way, as described above, the electromagnetic pump,
For the molten metal coagulation zone provided close to the outer circumference of the pressure stem and pressure pin, if the molten metal casting speed by using the electromagnetic pump and the vacuum suction mechanism together is set to the optimum value of 1.0 to 2.4 m / sec. The air resistance in the two-stage voids such as voids and gas exhaust voids increases, but by appropriately selecting the number and arrangement of the pressure pins, it is possible to achieve the above-mentioned purpose of installing the voids for the molten metal coagulation zone and the gas exhaust voids. You can That is, a person skilled in the art can easily design a structure in which the preheated metal is cooled and solidified in the gap for the molten metal solidification zone of the two-stage void and does not enter the gas discharge void or the gas discharge groove narrower than the gap for the molten metal solidification zone. it can. In order to surely cool and solidify the preheated metal in the molten metal coagulation zone, a material with good thermal conductivity such as beryllium copper should be used for the pressure stem and pressure pin, and the structure should be water cooled. You can also

In the vertical casting method of the present invention, the vertical casting apparatus of the present invention is used to cast the molten metal into the cavity of the mold from the molten metal holding furnace through the connecting duct of the electromagnetic pump, and the molten metal fills the cavity. After that, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized so that there are no shrinkage cavities during solidification and no gas entrainment, preferably a light metal alloy. Although it is not particularly limited as long as it is a casting method for casting a large-sized thin-walled cast product, at the retracted position of the pressure pin, filling of the molten metal into the mold cavity is started, While decelerating in the cavity second hot water reservoir and discharging the gas in the mold cavity from the gas discharge gap or the gas discharge groove, the melt in the mold solidification zone is cooled and solidified, and the mold cavity is filled with the melt. Was done It is preferable that one or a plurality of pressurizing pins be advanced to pressurize the molten metal in the molten metal reservoir, and the gas is discharged by vacuum degassing from the gas discharge gaps or gas discharge grooves adjacent to the plurality of molten metal solidification zones. It is preferable to further reduce the entrainment of the molten metal and to shorten the pressure transmission distance by pressurizing the molten metal with the pressure stem and the plurality of pressure pins. When the molten metal solidifies and the replenishment and filling of the molten metal is completed, the movable platen is moved up by the movable platen after a short cooling time, and the product material is lifted up along with it and the product material is moved by the pressure stem and the pressure pin and the extrusion pin. The product is extruded from the pressurizing pin, then ejected from the pressurizing pin and ejected from the pressurizing pin and the pressurizing pin, and the product material is taken out. be able to. Further, since such an operation is repeated every time, the solidified molten metal in the void for the molten metal solidification zone is removed each time, and the gas discharge passage is not clogged.

[0027]

Embodiments of the present invention will be specifically described below with reference to the drawings, but the technical scope of the present invention is not limited to these embodiments. 1 is a schematic vertical sectional view of the vertical casting apparatus of the present invention, FIG. 2 is a sectional view taken along the line AA ′ of FIG. 1, and FIG.
FIG. 4 is an explanatory view showing a sucked state of molten metal, and FIG. 4 is an explanatory view showing an operating state following FIG. 1 to 4, 1 is a fixed mold, 2 is a movable mold, 9 is a cavity product part, 10 is a circular gate, 11 is a cavity first molten metal reservoir part, 13 is a closing pin, and 14 is a pressure stem. , 17 is a void for the molten metal coagulation zone (outer periphery of the pressure stem), 19 is a cavity second hot water reservoir, 2
Reference numeral 0 is a pressure pin, 21 is a space for melt solidification zone (outer periphery of the pressure pin), 29 is a pressure stem gas discharge hole, 34 is a pressure pin gas discharge hole, 40 is an electromagnetic pump, and 41 is a communication duct.

The casting apparatus of the present invention shown in FIGS. 1 to 4 is a fixed mold 1 attached to a horizontal fixed platen 3 at the bottom of the casting apparatus, which can be moved up and down to perform mold closing. And a movable mold 2 attached to a horizontal movable platen 4 above the casting apparatus, an electromagnetic pump 40 attached below the fixed mold 1 and immersed in the molten metal 7 in the molten metal holding furnace 6, and an inflow gate. And a communication duct 41. Then, by closing the fixed mold 1 and the movable mold 2 via the seal packing 35, the cavity product part 9, the cavity first hot water reservoir 11, the cavity second hot water reservoir 19, and the cavity product. A mold cavity including a side gate 12 that communicates the portion 9 and the cavity first molten metal reservoir 11 is formed. Further, the mold is attached by moving the movable platen 4 of the mold clamping press device (not shown) in a movable state with the fixed mold 1 to which the electromagnetic pump 40 and the communication duct 41 are attached via the seal packing 38. A set of dies consisting of dies 2 is loaded, placed on the fixed platen 3, and the movable platen 4 is lowered until it comes into contact with the upper surface of the movable die 2, and the fixed die 1 is placed on the fixed platen 3 and the movable die. The mold 2 is attached to the movable platen 4 and is moved by a hydraulic cylinder having a mold clamping force that prevents the mold from opening due to the reaction force when the molten metal under pressure is supplied into the mold cavity by the driving force of the electromagnetic pump. This is done by pressing the platen 4.

In the fixed mold 1, the molten metal is connected to the connecting duct 4 by the driving force of the electromagnetic pump 40 by the action of the electromagnetic coil 39.
A circular gate 10 for discharging the molten metal from the mold 1, sucking the molten metal by evacuating the mold cavity, and ejecting the molten metal tip.
Is provided. When the electromagnetic pump 40 is driven and the inside of the cavity is depressurized, the molten metal 7 in the molten metal holding furnace 6 is pushed up into the communication duct 41 by the pressure difference between the driving force of the electromagnetic pump 40 and the atmospheric pressure, and the fixed mold is formed. Circular gate 1
It is filled in the cavity product part 9 through 0. The pouring speed at this time is controlled by adjusting the driving force of the electromagnetic pump and the degree of vacuum in the cavity so that the molten metal passes through the circular gate 10 quickly and becomes a jet flow and is jetted upward. In addition, as shown in FIG.
The inlet diameter d ₁ of the hot water reservoir 11 is configured to be 1.4 times or more the diameter d of the circular gate 10, and the outer diameter d of the pressurizing stem 14 is set.
s is configured to be slightly smaller than the inlet diameter d _{1 of the} hot water reservoir 11, and the ceiling height of the first cavity hot water reservoir 11 is given by the formula: h = v ² / 2g (where h is the jet arrival height) , V is the circular gate passage speed, and g is the acceleration of gravity.) The height is higher than the height h reached by the molten metal jet 15 passing through the circular gate 10. Therefore, in the initial stage of filling, the jet flow does not collide with the ceiling of the cavity first molten metal reservoir 11, a free surface of the molten metal jet 15 is formed on the upper portion thereof, and the descending flow of this portion disappears, so that the molten metal surface Oxide remains stationary and pool 1
As a result of eliminating the gas remaining in the upper part of No. 1 from getting into the molten metal 16, the molten metal jet flow 1 passing through these circular gates 1
The slight oxide film and solidified layer at the tip of 5 all remain in the cavity first molten metal reservoir 11, and only clean molten metal without entrapment of oxide or gas passes through the side gate 12 and the cavity product portion 9 Will be filled inside.

A hydraulic cylinder 25 is liquid-tightly disposed in the movable mold 2 above the circular gate 10 via a seal packing 27, and the pressurizing stem 14 is hydraulically attached to the hydraulic cylinder 25 by the cavity first. A pressurizing stem piston 23 capable of advancing and retracting to and from the hot water reservoir 11 is housed via a seal packing 27, and the pressurizing stem piston 23 is provided with a closing pin 13 capable of closing the circular gate 10. A closing pin piston 24 that can be advanced and retracted is accommodated coaxially with the pressure stem piston 23. After the mold cavity is filled with molten metal,
The closing pin 13 is moved forward by the piston 24 to close the circular gate 10, and immediately thereafter, the pressure stem 14 is moved forward by the piston 23, and the volume of the unfilled void in the cavity product portion 9 and the molten metal corresponding to the solidification shrinkage volume are melted. Pressure is supplied from the cavity first hot water reservoir 11. At this time, since the stalk of the pressure stem 14 is large, a sufficient amount of molten metal can be replenished and pressure-filled.

Even during pressurization by the pressurizing stem 14, a slight amount of oxide is generated on the molten metal surface in the communication duct 41 of the electromagnetic pump 40, and the solidification of the surface of the molten metal formed by cooling at the inlet of the circular gate 10 The gas entrained layer generated by the layer or the jet flow gathers at the uppermost part of the hot water reservoir 11 by the gate jet flow 15, remains in the cavity first hot water reservoir 11 without being extruded by the pressure stem 14, and the cavity product portion 9 As a result, there are no casting defects caused by these. Further, on the outer periphery of the pressurizing stem 14, there is provided a two-stage space including a gas discharge space 18 communicating with the gas discharge hole 29 and a melt solidification zone space 17. As shown in FIG. 4d, the gas discharge void 18 is secured every time the casting is performed because the solidified layer formed in the molten metal solidification zone void 17 is taken out together with the product material.

Further, one or two or more small cavity second hot water reservoirs 19 are formed above the ends of the cavity product portion 9, and the movable mold 2 above the hot water reservoir 19 is provided with: A hydraulic cylinder 31 is provided, and the hydraulic cylinder 31 accommodates a pressure pin piston 30 that can move the two pressure pins 20 back and forth to and from the cavity second hot water reservoir 19. The one or more pressing pins 20 have an axis in a direction parallel to the mold opening / closing direction and orthogonal to the mold parting surface, and are liquid-tightly provided to the movable mold 2 via the seal packing 33. . Also on the outer circumference of these pressurizing pins 20, there are provided two-stage voids, which are a gas exhaust void 22 communicating with the gas exhaust hole 34 and a molten metal solidification zone void 21. Then, after replenishing and filling the inside of the cavity product portion 9 with the pressure stem 14, these pressure pins 20 are pushed out to pressurize the molten metal of the cavity product portion 9 through the cavity second molten metal reservoir portion 19. ing. Further, the outer diameter of the pressurizing pin 20 is configured to be slightly smaller than the diameter of the inlet of the cavity second hot water reservoir 19. Since these pressurizing pins 20 also slide every time, the solidified layer formed in the molten metal solidification zone voids 21 is extruded by an extruding pin (not shown) in a state of being attached to the product material and does not remain in the gas passage holes, and the gas discharge passage Is being secured.

Next, the operation will be described. After mold clamping is completed,
The molten metal 16 is sucked up into the cavity first molten metal reservoir 11 by the driving force of the electromagnetic pump 40 and the vacuum suction force into the cavity. The molten metal 16 rises in the communication duct 41, passes through the circular gate 10 of the fixed mold 1 and is ejected (FIG. 3), and then is filled in the cavity product portion 9. Generally, since there is a flow resistance in the cavity product portion 9, before the molten metal reaches the cavity second molten metal reservoir portion 19 below the pressurizing pin, the cavity first molten metal reservoir portion 11 above the circular gate 10 is provided. Is filled with the molten metal (Fig. 4a), but when the preceding molten metal enters the two-stage voids 17 and 21 for the molten metal coagulation zone, the passage is narrow, the heat capacity of the molten metal is small, and conversely the cooling area is large. Since the cooling rate is high, the solidification progresses, and the fluidity decreases, the tip of the molten metal does not stop in the middle of the gap 17 for the molten metal solidification zone and does not solidify and enter the gas discharge void 18.

When the flow of the molten metal in the cavity is stopped, it is detected as a signal indicating the completion of filling, and the closing pin 13 is immediately advanced to insert and close the circular gate 10 (FIG. 4b). In this way, after the molten metal in the cavity product portion 9 and the cavity first molten metal portion 11 is blocked so as not to flow back into the communication duct 41, the pressure stem 14 is immediately advanced to pressurize the molten metal in the cavity first molten metal portion 11. The molten metal in the semi-solidified state is refilled into the cavity product portion 9 (FIG. 4c). When the filling is completed and cooling is started, solidification shrinkage of the molten metal 16 occurs. Therefore, high pressure is applied to the pressurizing stem 14 to advance it, and replenishment is performed according to the solidification shrinkage volume. Circular gate 1 with blocking pin 13
Even if the contact between the closing pin 13 and the circular gate 10 is not perfect at the time of 0 closing, the molten metal existing in the small voids quickly cools and solidifies, and the molten metal flows from the circular gate 10 into the communication duct 4
1, the molten metal in the gate 10 and the communication duct 41 cannot rise, and the current is flown back to the electromagnetic coil 39, so that the communication duct 41
A downward force is applied to the remaining molten metal and the material is dropped into a holding furnace.

In the case of replenishment and filling by the pressure stem 14, the resistance is small, the force of the pressure cylinder of the pressure stem 14 is small, and the hydraulic pressure in the hydraulic cylinder can be advanced in a low state. By the refilling and filling by the advance of the pressure stem 14, the molten pin refills and fills the cavity product part 9 and the cavity second hot water reservoir part 19, and then the pressurizing pin 20 is advanced. The pressurization by the pressurizing pin 20 is started by detecting the fact that the flow resistance increases and the hydraulic pressure rises with the completion of the filling by the pressurizing stem 14. Replenishment according to the solidification shrinkage volume due to the advancing of the pressure stem 14 is difficult to transmit pressure up to the opposite end of the cavity product portion 9. Therefore, the pressurizing pin 20 around the end is actuated to pressurize the entire surface. As a result, it is possible to obtain a densely structured product without shrinkage cavities due to coagulation and condensation. After the cooling and solidification of the molten metal in the cavity product portion 9 is completed, the mold material is opened and the product material lifted by the movable mold can be extruded and taken out by the pressure pins and the extruding pins (FIG. 4).
d).

[0036]

When the casting apparatus of the present invention is used, the structure of the gas discharge system around the pressure stem and the pressure pin is simple, and troubles during operation are reduced. Also, by using an electromagnetic pump and a vacuum suction mechanism to fill the mold cavity with the molten metal at high speed, the molten metal precursor flows into the narrow gap for the molten metal solidification zone, where it solidifies and stops there. Never infiltrate. Also, by making the depth of the cavity first molten metal reservoir deeper, the stroke of the pressure stem can be lengthened, and a sufficient volume of molten metal for replenishment filling and solidification contraction in the cavity product portion can be obtained. By press-fitting, it is possible to obtain a cast product having a finer structure and strength. In addition, by closing the circular gate with a blocking pin slightly smaller than the inner diameter of the circular gate, and causing the current to flow backwards through the electromagnetic coil, the molten metal in the communication duct can be quickly returned to the holding furnace and the product can be taken out easily. be able to.

Further, in the casting apparatus of the present invention equipped with the electromagnetic pump and the vacuum suction mechanism, when the mold cavity is filled with the molten metal, the gas in the cavity is almost completely discharged, and at the same time, the circular gate is opened after the filling. Since it can be closed and the necessary and sufficient pressure can be applied with a small pressure, it can be
A mold clamping force of ⅓ to ⅕ can be used, the cost of the casting apparatus can be significantly reduced, and the cost of the cast product can be significantly reduced. In addition, since the molten metal is directly supplied from the holding furnace, no oxide is generated, and the passage is short, so that the solidified layer is less likely to be generated, and the cavity first molten metal part having an appropriate height at the outlet of the circular gate. Since the jet flow does not collide with the ceiling, the gas entrainment can be eliminated, and a small amount of oxide or solidified layer that remains may be retained in the cavity first molten metal reservoir, resulting in a dense structure with no impurities. It is possible to obtain a cast product having a different structure. Furthermore, unlike the low pressure casting, the molten metal holding furnace is not closed, so it is easy to replenish the molten metal and not only the equipment cost is low, but also the arrangement and operation of the equipment such as raising the molten metal surface and shortening the communication duct are possible. It will be easier.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a vertical casting apparatus of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory diagram showing a suction state of molten metal in the vertical casting apparatus of the present invention.

FIG. 4 is an explanatory view showing an operating state in the vertical casting apparatus of the present invention following FIG.

[Explanation of symbols] 1 Fixed mold 2 movable mold 3 Fixed platen 4 movable platen 6 Molten metal holding furnace 7,16 molten metal 8 Hot water surface 9 Mold cavity 10 round gate 11 Cavity 1st hot water reservoir 12 side gates 13 Blocking pin 14 Pressure stem 15 jets 17 Pressurized stem molten metal coagulation zone void 18 Pressurized stem gas discharge space 19 Cavity No. 2 hot water reservoir 20 pressure pin 21 Pressurizing Pin Void for molten metal coagulation zone 22 Gas discharge space around pressurizing pin 23 Piston for pressure stem 24 Piston for closing pin 25 hydraulic cylinder 26 Pressure oil inlet a, b, c 27 Pressure stem Seal packing 28 Blocking pin Seal packing 29 Pressure stem Discharge passage 30 Pressure pin Piston 31 Pressure pin Hydraulic cylinder 32 Pressure oil inlet 33 Pressure pin Seal packing 34 Pressurizing pin Gas discharge passage 35 mold seal packing 36 Pressure stem cooling water hole 37 Pressure pin cooling water hole 39 electromagnetic coil 40 electromagnetic pump 41 Communication duct

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22D 35/00 B22D 35/00 C 41/18 41/18

Claims (5)

[Claims] 1. A fixed mold on the lower side and a movable mold on the upper side capable of forming a mold cavity, pouring means for supplying and filling molten metal into the mold cavity from below, and the pouring means. After the molten metal cast in the mold cavity is filled by the, the closing means for closing the molten metal inflow gate provided in the fixed mold, and the pressurization for pressurizing the molten metal in the closed mold cavity In the vertical casting apparatus provided with a means, an electromagnetic pump is used as the casting means. 2. The mold cavity comprises a gas discharge passage,
The vertical casting apparatus according to claim 1, wherein a molten metal coagulation zone void communicating with the gas discharge passage is provided in the vicinity of the gas discharge passage. 3. As a casting means for filling the mold cavity with molten metal from below, in addition to the electromagnetic pump, it is provided below the fixed mold by vacuum suction of gas in the mold cavity. The vertical casting apparatus according to claim 2, further comprising a vacuum suction mechanism that vacuum-fills the molten metal from the lower molten metal holding furnace through the casting stalk. 4. The vertical casting apparatus according to claim 1, wherein the molten metal is cast from a molten metal holding furnace into a cavity of a mold through a connecting duct of an electromagnetic pump, and the molten metal fills the cavity. After that, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized to cast a cast product with no shrinkage cavities during solidification and no gas entrapment. Characteristic solid casting method. 5. The casting method according to claim 4, wherein the casting is a thin and large casting of a light metal alloy.