JP2016120518A - Die cast method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die cast method which prevents a die cast product, often non-uniform in wall thickness, from making solidification time different with each part and from being incapable of attaining directional solidification.SOLUTION: An aluminum die cast method comprises the step of depositing a heat insulation film on the surface of a movable mold coming in contact with a cavity with a film thickness corresponding to each wall thickness of parts with different wall thicknesses of an aluminum die cast product and on the surface of a stationary mold after the mold opening step, a capsule housing step for housing an adiabatic capsule where a molten metal is held in a sleeve space generated by making a plunger tip arranged in the sleeve of a main injector communicating with the cavity retreat in the sleeve, a mold closing step for clamping the mold by moving the movable mold in the direction of the stationary mold, a vacuum step for decompressing the interior of the cavity, and the step of filling the molten metal held in the capsule into the cavity by advancing the plunger tip toward the cavity in the sleeve to move the capsule to the cavity, and by breaking the capsule after the mold closing step.SELECTED DRAWING: None

Description

The present invention relates to a die casting method. More specifically, the present invention relates to a manufacturing technique of aluminum die casting, and relates to a method capable of manufacturing a high-quality (no casting defect) die-cast product and also capable of manufacturing a thin-walled and large-sized aluminum die-cast product. It is.

For example, when a product (for example, a suspension member for an automobile) having a thickness of about 3 mm, a width of about 500 mm, and a length of about 1000 mm is manufactured by a conventional aluminum die casting method, a vacuum die casting method is employed.

In the vacuum die casting method, high-speed and high-pressure injection plungers, runners for evenly supplying molten metal, gates, product cavities, decompression runners for vacuum suction, vacuum valves, etc. are placed in a large mold and clamped. -Injecting and requiring complex and large molds and die casting devices (eg 3000 ton clamping devices, 3-5 m / s plunger injection speed) to perform extrusion.

In order to manufacture larger and thinner products (for example, door panels with a thickness of 2 mm x width of 1000 mm x length of 1500 mm, etc.), further increase in speed and pressure, ultra-large molds, die casting equipment (for example, 4000 tons) A mold clamping device (5-8 m / s plunger injection speed), which is practically expensive and difficult or impossible.

On the other hand, it is completely impossible to produce such a thin and large product by the conventional low speed / low pressure method (gravity casting method or low pressure casting method) or low speed / high pressure method (squeeze die casting). In order to enable low-cost production of thin-walled and large-sized die castings, an invention of a die casting method having a low speed, low pressure, and a simple and compact configuration is absolutely necessary.

Here, the reason why high-speed and high-pressure vacuum die casting was necessary in conventional die casting will be described.
(A) It is necessary to inject at high speed so as not to solidify during filling.
(B) It is necessary to reduce the pressure in order to prevent air entrainment in the cavity or to make it vacuum. (However, since a complete vacuum is not possible, there is always residual air.)
(C) It is necessary to increase the pressure in order to compress the air entrained by high-speed filling.
(D) It is necessary to apply high pressure to compensate for coagulation shrinkage.
That is, in the conventional die casting, the quality of the die cast product could not be ensured unless high speed and high pressure were used. However, there was a limit to high speed and pressure.

Accordingly, the present inventor has proposed a die casting apparatus and method according to the following Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4.

According to Patent Document 1,
(1) Simplification of die-casting equipment has been realized with an injector that has vacuum, injection, pressurization and extrusion functions.
(2) The temperature drop was eliminated by supplying the molten metal with the heat insulating capsule, the pouring amount was easily managed, and the handling was facilitated.
(3) Since it has a simple die-casting structure, the effect of less vacuum leak was obtained.
(4) Since a plurality of injectors can be arranged directly at the optimum position in the die-cast product by solidification, flow, and extrusion, it is possible to produce a large and thin product.
(5) Since a long suction time can be taken, the number of leak sites is reduced, and a high degree of vacuum can be achieved.
(6) The structure in which the injection pressurization position is directly provided in the product shortens the flow distance of hot water, making it easy to prevent hot water and shrinkage.
(7) In addition, since the runner, gate, and overflow are unnecessary, the size of the mold is reduced, and thus the yield is improved.
(8) Due to the shortened hot water flow distance and high vacuum, low-speed and low-pressure injection became possible, and the mold and die casting equipment became compact.

According to Patent Document 2,
(1) A method for handling heat-insulating capsules and filters was proposed.
(2) Proposed application of heat-retaining coating agent and auxiliary runner ribs to die casting (application in ultra-thin, large-sized die casting products).
(3) A biscuit separation method was proposed.

According to Patent Document 3, in order to more efficiently obtain the high-quality aluminum die casting in Patent Documents 1 and 2 above, it is easy to replace the mold that integrates multiple injection, vacuum, pressurization, and extrusion mechanisms. In addition, we are proposing a die casting system device that efficiently performs a series of processes, such as pouring, to dramatically increase the operating rate and non-defective product rate. That is, according to Patent Document 3,
(1) Proposed a compact mold with injection / vacuum / pressurization / extrusion and a rapid mold changer (horse-shoe platen),
(1-1) A compact mold having all the configurations such as <multiple injection servo mechanism, vacuum, extrusion mechanism> and the like.
(1-2) Since it was set up externally, wiring piping and mold preheating became possible, discarding was eliminated, and the operating rate and non-defective rate were improved.
(1-3) Since the die casting machine main body has only a mold opening / closing mechanism, it has a simple structure (a horseshoe type platen, a slide type quick mold change, and a clamping force is one tenth or less of the conventional method. There is no deformation of).
(2) It was proposed that <poured capsule and heat transfer device> be prepared in advance and supplied quickly and quietly. That is,
(2-1) In order to stabilize the pouring amount and pouring temperature with high accuracy and the pouring temperature, it was proposed to check the pouring amount and temperature with a heat retaining capsule and supply hot water.
(2-2) In order to realize a clean molten metal, contact / cooling with the sleeve / plunger was eliminated by eliminating a drop during pouring.
(2-3) In order to realize quick hot water supply, it was proposed to supply hot water quietly and quickly using the movement of the plunger.

According to Patent Document 1, Patent Document 2, and Patent Document 3, high-quality, ultra-thin and large-sized die-cast products can be manufactured. However, there is a point that should be improved in terms of the use of a heat insulating material and the use of an injector with a vacuum function, and the inventor has further improved the invention by the invention disclosed in Patent Document 4 below. Realized the method of manufacturing quality die casting products.

The present inventor disclosed in Patent Document 4
(1) A method for preventing solidification in the sleeve without a heat insulating material was proposed.
In the vertical die casting method, the low-pressure and high-pressure injection is usually used for relatively small and thick products. Patent Document 4 is an invention of a simple configuration that has a plurality of injection cylinders and enables low pressure in order to produce a large and thin product, and does not require a heat-insulating capsule, which is an essential component in Patent Document 1 above. .
When there is no heat insulating material, if it takes a long time from pouring to injection, solidification proceeds in the sleeve, which causes a problem of injection trouble and poor hot water.

Therefore, after completion of the <opening of mold, casting removal, cleaning, and release material application> process, the mold is kept in a semi-closed state (for example, close to about 3/4), and the mold is poured by a pouring jig (heat retaining rod). Pour hot water through the gap.
At the time of this pouring, the plunger tip is lowered according to the amount of pouring, and the pouring drop is minimized to prevent hot water turbulence and generation of oxidized components.
After removing the pouring jig, the mold is further closed. As a result, the conventional mold closing stroke (for example, 600 mm) can be shortened to about 150 mm, so that the mold closing time is conventionally 15 seconds, for example, about 4 seconds (pouring jig removal + mold closing time). ), It is difficult for the molten metal in the injection sleeve to solidify.
Further, by using a heat retaining sleeve lubricant and a heat retaining sleeve in combination, the progress of solidification can be further slowed, so-called solidified layer (break chill layer) on the inner surface of the sleeve can be eliminated, and more Ejection is easily possible as well.

Moreover, this inventor is the patent document 4,
(2) A simple method was proposed to rapidly evacuate the mold cavity.
After completion of the pouring step, the mold is further lowered to open a gap (about 2 mm (this is a gap where the vacuum seal is effective)), and the mold is held at that position for a short time. Immediately thereafter, the vacuum system is opened and the inside of the mold cavity is kept at a high vacuum. That is, high vacuum can be easily achieved by eliminating a vacuum DC valve, a chill vent, or an injector having a vacuum function. Further, since the mold gap is as large as about 2 mm and the suction area is wide, a high vacuum can be achieved in a very short time (for example, 1 second). After reaching high vacuum, the remaining gap is completely closed and injection is performed.

The processes (1) and (2) of Patent Document 4 can be performed with a short stroke (for example, about [4 + 1] seconds) from the completion of the pouring step to the injection step, and solidification of the molten metal in the sleeve is As a result, a heat insulating capsule made of a heat insulating material becomes unnecessary, and a special pouring mechanism and a vacuum mechanism become unnecessary.

Moreover, this inventor is the patent document 4,
(3) A method for ensuring the pressure effect from biscuits was proposed.
When the injection is performed, the molten metal that passes through the filter and is clean is injected into the mold cavity to form a biscuit portion. Solidification inside the sleeve can be minimized by the processes (1) and (2) above, but solidification progresses slightly during filling, so a solidified shell is gradually generated on the mold contact surface, and the plunger There may be a case where pressure is not sufficiently applied due to resistance of the pressure stroke. Therefore, in order to avoid the solidified shell, the tip diameter of the plunger is made smaller than that of the biscuit so that the plunger tip can enter the inside of the biscuit. As a result, the pressure of the plunger can be propagated to the product through the non-solidified portion, and the coagulation contraction can be prevented at a lower pressure than in the past. In the past, high pressure was required to crush the solidified shell (having strength).
It is also an important point that enables low pressure injection by setting the position of the biscuits high so that the so-called gravity hot water is effective.

By the above processes (1), (2) and (3), a special pouring mold mechanism (for example, a tilting sleeve method), a baculal method (vacuum suction method) without using a special heat insulating material. In the vertical die casting method, the low pressure pouring method (MP method) or the like is not required, and further, an expensive vacuum valve or chill vent is not required, and the mold closing stroke is maintained in three stages. Large and thin products can be made easily at low speed and low pressure. Furthermore, two or more injections can be easily performed.

As described above, the methods of Patent Documents 1 to 4 have been briefly described. In Patent Document 1 and the like, a sleeve heat retaining capsule is used. The heat insulating material holds a high-quality molten metal and is very effective in manufacturing a high-quality die-cast product. However, since there is a problem with the heat insulating material cost, in Patent Document 4, the heat insulating material is quickly used without using this heat insulating material. The invention of injecting molten metal into the water was proposed.

Japanese Patent No. 4810706 JP 2010-179331 A JP 2012-148319 A JP2013-132644A

The heat insulating material disclosed in the above-mentioned Patent Document 1 etc. is a heat insulating effect, prevents contact with the sleeve, and ensures the cleanliness of the molten metal. It is desirable to make it thinner.
However, there is a risk of breakage during pouring, and molding is difficult, and there is a limit to reducing the thickness (thickness 1 mm or less). In order to provide a die casting method capable of easily performing thin film molding and preventing breakage during pouring, the present inventor disclosed in Japanese Patent Application No. 2013-205708 that the molten metal was solidified without contacting the inner surface of the sleeve. It does not progress, so-called solidified chill layer does not occur, and the plunger lubricant does not contact the molten metal, so no reaction gas is generated, and it is possible to hold the clean molten metal stably and the amount of the heat insulating material is small. Therefore, the influence on the flow can be minimized. And it becomes possible to manufacture a high-quality die-cast product by the thin film adhesion method.

Unlike the conventional die casting, the multi-injection methods disclosed in the above-mentioned Patent Documents 1 to 4 can manufacture a high-quality, thin-walled and large-sized die casting product. In other words, the solidification of the molten metal in the injection sleeve is prevented, a high vacuum is secured, a plurality of injection sleeves are installed, and the required flow distance from each sleeve is shortened. (About 1/10). The inventions of Patent Literatures 1 to 4 disclose methods that are basic or related to them. Patent Documents 1 to 3 disclose a method of supplying a plurality of molten metal with a plurality of molten metal heat-insulating capsules and performing a plurality of injections. Patent Document 4 discloses a method without a heat insulating material, and Japanese Patent Application No. 2013-205708. Disclosed a thin-film insulation material method.

The thin film heat insulating material method has the merit that the thin film heat insulating material is brought into close contact with the inner wall of the injection sleeve and can prevent the temperature drop and contamination of the molten metal, while multiple heat insulating material insertion, multiple pouring, mold clamping, vacuum, There is a demerit that the number of processes increases due to take-out, air blow, release agent application, and multiple sleeve lubricant application, and if these processes are performed sequentially, the cycle time becomes longer and the merit of die casting with good manufacturability is lost There is a problem.

The present inventor has proposed a die casting apparatus and method improved by Japanese Patent Application No. 2013-264618 in view of the above technical problems. In this die casting apparatus and method, the injection pressure is higher than that of conventional die casting. Therefore, the clamping force can be greatly reduced. For this reason, it becomes possible to apply the said hydraulic clamp system.

The present inventor further provided, in Japanese Patent Application No. 2013-264619, a technical problem to provide a sand core capable of easily obtaining an undercut or hollow aluminum die-cast product, and a die casting method using the sand core, A step of preparing such a technical problem by kneading one or more particles selected from the group consisting of zircon sand, chromite sand, and alumina sand, and an inorganic binder (1 to 3% by weight), and a sand mold Selected from the group consisting of zircon sand, chromite sand and alumina sand, and a method for producing a sand core used in low-speed low-pressure die casting by one or more injections, characterized in that it comprises a molding step for producing a core A core for thin-walled large-sized die castings, comprising one or more kinds of particles and an inorganic binder (1 to 3% by weight), and aluminum using the core A step of inserting the core described in the sand core manufacturing method together with the heat insulating material between the upper mold and the lower mold, and the heat insulating material in the inner wall of the plurality of injection sleeves. A step of adhering to the heat insulating material, a step of pouring the molten metal into the heat insulating material, a step of closing and clamping the upper die, a step of injecting the molten metal, a step of solidifying the hot water, a step of raising the upper die after solidification of the hot water And an aluminum die casting method characterized by comprising a step of extruding the product together with the core from the upper die.

The advantage of the die casting method according to Japanese Patent Application No. 2013-264619 is that an aluminum die-cast product can be manufactured at an ultra-low speed and an ultra-low pressure, but further, the advantage is that sand that is difficult to use with conventional high-speed and high-pressure die castings. A core can be used.

The present inventor has realized the casting of a thin and large die-cast part by the inventions disclosed in the above-mentioned patent documents 1 to 4, Japanese Patent Application Nos. 2013-205708, 2013-264618 and 2013-264619. However, it has been recognized that the following problems occur when casting an actual aluminum die-cast product.

(A) A die-cast product usually does not have a uniform wall thickness, and directional coagulation cannot be achieved due to the different coagulation time for each part. That is, solidification of the boss-shaped part and the thick part is delayed, the pressure from the plunger is not effective, and a shrinkage nest is generated. When multiple plungers are used as described in Japanese Patent Application Nos. 2013-264618 and 2013-264619, these are improved, but there are some shapes that are impossible by themselves.
(A) If a thin part exists, coagulation is promoted at that part, resulting in poor hot water. It is necessary to shorten the filling time as a measure against hot water around the thin part.
(C) As an aluminum product, it is important to reduce the thickness and weight, and a thinner product is required than before. However, due to strength and necessity of fastening, the thickness is not uniform, but it must be partially thin or thick.

In the countermeasure (1), as a conventional die casting method, the first countermeasure is to cast a thick-walled portion or a boss portion or to change the shape. Furthermore, depending on the case, a countermeasure may be taken by installing a pressure pin in the solidification delay portion and applying pressure after filling. However, there is a limit to the change of shape, and the pressure pin is difficult to mold and control and causes trouble.

As a countermeasure against the thin parts (a) and (c), the filling speed is increased. However, this is limited in that the die casting apparatus becomes complicated and expensive. In addition, as a countermeasure against hot water around thin parts, a release agent with good heat retention may be used, or fine irregularities may be provided on the mold surface, or a mesh pattern may be provided, but the effect is not sufficient.

On the other hand, in the gravity mold casting method and the low pressure casting method, coating to the mold, that is, coating, is performed, and the coating film thickness is increased, heat retention is ensured and solidification is delayed, or conversely, the coating film is applied. Accelerating coagulation by thinning is qualitatively and empirically performed (see FIG. 8).

The coating mold used in the normal mold gravity casting method is a state in which the mold is heated (around 200 ° C.) with various refractory powders (alumina, kaolin, graphite, mica, refractory clay, etc.) mixed with a binder. Then, spray and fix it on the mold surface. This coating mold is relatively soft, but is usually durable enough to be used for one to several days by gravity casting or the like, and in some cases, repairs are performed as needed. However, there is a problem that the film thickness decreases as the casting is repeated, and the effect does not continue stably. In addition, the filling speed and the molten metal pressure are at a very low level compared to die casting, which is not a suitable process for manufacturing a thin large casting.

It is difficult to apply die casting to such a coating method in gravity casting. The reason is that in gravity casting or low pressure casting, filling is performed at a low speed with gravity or air pressure, and the applied pressure is about the gravity, whereas in the normal die casting method, the molten metal speed is high (for example, plunger speed 3). ~ 5m / s, gate speed 50m / s), high molten aluminum pressure (for example, 500 atm to 1000 atm), these coating films peel or break, and molten aluminum penetrates into the pores in the film This is because there is no durability of the coating mold.

Thus, the gravity mold casting method has no durability at all in ordinary die casting. Therefore, the possibility of ceramic spraying with a slightly higher adhesion strength and film strength is considered, but at the above normal die casting molten metal pressure and speed, it is not as durable as the gravity mold casting coating mold. In other words, the sprayed film melts ceramic or metal with plasma, high-speed flame, etc. and sprays it on the metal surface, but the sprayed film has many minute openings, the high-pressure aluminum melt penetrates, and the aluminum mold release This is because the sprayed film sometimes peels off. In some cases, it is possible to seal the ceramic, but it cannot be completely sealed, and cracks are liable to occur. On the contrary, the high-pressure molten metal penetrates into the cracks and peels easily. Further, the interface between the sprayed film and the mold has no chemical bonding force and weak adhesion. Although metal spraying is performed on the underlayer and ceramic spraying with good heat retention is performed on the upper layer, durability with conventional high-speed and high-pressure die casting is insufficient.

The die casting method according to the first aspect of the present invention includes:
(1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) Capsule housing step of housing a heat-insulating capsule in which a molten metal is held in a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity in the sleeve When,
(4) a closed mold step of clamping the mold by moving the movable mold in the direction of the fixed mold after the capsule housing step;
(5) a vacuum process for reducing the pressure in the cavity;
(6) After the mold closing step, the plunger tip is advanced in the sleeve toward the cavity, the capsule is moved to the cavity, the capsule is broken, and the molten metal held in the capsule is removed. An injection process for filling the cavity;
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) The method includes an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold.

The die casting method according to the second aspect of the present invention comprises:
(1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) A thin-film heat insulating material molded into a cylindrical shape is inserted into a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity, and A process of pouring molten metal into a cylindrical thin film heat insulating material;
(4) In the above step, after completion of pouring of the molten metal, a closed mold step of clamping the mold by moving the movable mold in the direction of the fixed mold,
(5) a vacuum process for reducing the pressure in the cavity;
(6) After the mold closing step, the plunger tip is advanced toward the cavity in the sleeve, and the cylindrical thin film heat insulating material filled with the molten metal is moved to the cavity. An injection step of breaking the thin film heat insulating material and filling the cavity with the molten metal held in the thin film heat insulating material,
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) The method includes an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold.

The die casting method according to the third aspect of the present invention includes:
(1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) A space between the movable die and the fixed die is formed in a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity. A housing process for injecting molten metal;
(4) After completion of pouring of the molten metal in the step, the movable mold is moved in the direction of the fixed mold, and the movable mold and the fixed mold are held in a state of being opened for a predetermined time. Process,
(5) a vacuum process for reducing the pressure in the cavity;
(6) After reaching the high vacuum after the step, the movable die and the stationary die are completely closed, and then the plunger tip is advanced toward the cavity in the sleeve, An injection process for filling the cavity with molten metal;
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) The method includes an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold.

Before the step of forming a heat insulation film on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the different thicknesses of the aluminum die cast product, the movable mold It is preferable that the method includes a step of performing shot scoring on the inner surface of the mold and the fixed mold.
The step of forming a heat insulation film on the surface of the movable mold and the fixed mold in contact with the cavity at a film thickness corresponding to each thickness of the different thickness of the aluminum die cast product includes the movable mold and It is preferable to form a thermal spray coating by forming a metal sprayed film on the inner surface of the fixed mold and performing ceramic spraying on the metal sprayed film to form a ceramic sprayed film.

The thickness of the metal sprayed film is preferably about 50 μm.

The metal sprayed film is preferably a Ni-Cr system.

The thickness of the ceramic sprayed coating is preferably about 5 to 300 μm.

The ceramic sprayed coating is preferably zirconia-based, calcia-based, or alumina-based.

In the die casting method according to the fourth aspect of the present invention, the step of forming a heat insulation film on the surfaces of the movable mold and the fixed mold in the inventions according to the first to third aspects,
(I) performing a hot water flow solidification simulation and determining a site where solidification is slowest;
(Ii) determining the film thickness of the thermal insulation film so as to have the same solidification time as the latest solidification time determined by the above-mentioned steps;
(Iii) a step of determining a thermal resistance value from the correlation between the film thickness and the thermal resistance value, and again performing a molten metal flow solidification simulation with the determined thermal resistance value;
(Iv) confirming that the coagulation time of each part of the product to be molded is substantially the same coagulation time;
(V) if there is a part where the coagulation time is different in the step (iv), a step of increasing or decreasing the thermal resistance value, confirming the coagulation time, and further changing to become directional coagulation;
(Vi) determining an optimum film thickness of the coating layer from an optimum thermal resistance value obtained by the simulation of the step (iii), and applying a coating treatment to the mold with the optimum film thickness; It is characterized by comprising.

According to the die-casting method according to the first to fourth aspects of the present invention, the solidification control by the mold heat insulation film even if the product to be molded which does not have a uniform thickness has a large and complicated shape. Die casting can be performed by performing the above.

It is a figure which shows the die-casting apparatus used for the die-casting method of Embodiment 1 of this invention. It is an enlarged view of the subinjector of the die-cast apparatus shown in FIG. It is a figure which shows the hot-water supply process ((a) of FIG. 3) and the injection | emission process ((b) of FIG. 3) of the die-casting method of Embodiment 2 of this invention. It is a figure which shows the hot water supply process of the die-casting method of Embodiment 3 of this invention. It is a figure which shows the vacuum process of the die-casting method of Embodiment 3 of this invention. It is a figure which shows the clamping process of the die-casting method of Embodiment 3 of this invention. It is a figure which shows the injection | emission process of the die-casting method of Embodiment 3 of this invention. It is a figure which shows the hot-water supply process ((a) of FIG. 3) of the die-casting method of Embodiment 3 of this invention. It is a graph which shows the relationship between the thickness of an aluminum die-cast product, the film thickness of a heat insulation film, and solidification time. It is a schematic diagram which shows an example of the die-cast product which has various thickness. It is a graph which shows the correlation with the film thickness of a heat insulating film, and a thermal resistance value.

[Embodiment 1]

Hereinafter, the die-casting device disclosed in the above-mentioned Patent Document 1 is suitably employed as the die-casting device according to the present invention.

FIG. 1 is a schematic view of a die casting apparatus according to the present invention. 1A is a plan view of a fixed mold of the die casting apparatus of the present invention, and FIG. 1B is a cross-sectional view of the die casting apparatus taken along line AA of FIG. (C) is sectional drawing of the die-cast apparatus in the BB line of Fig.1 (a). The die casting apparatus (1) of the present invention is connected to a movable mold (2), a fixed mold (3) disposed below the movable mold (2), and a fixed mold (3), A main injector (4) and a sub-injector (5).

The movable mold (2) and the fixed mold (3) are clamped in an overlapping state, and a cavity (6) is formed at the boundary surface between the movable mold (2) and the fixed mold (3). The cavity (6) has substantially the same shape as the outer contour of the desired die-cast product. In the example shown in FIG. 1, a concave mold (61) is formed on the upper surface of the fixed mold (3), a lower surface of the movable mold (2) is formed flat, and a fixed mold that defines the shape of the concave section (61). Although the cavity (6) is formed by the surface of (3) and the lower surface of the movable mold (2), the present invention is not limited to this, and the recess (61 on the movable mold (2) side is provided. ) And a form in which the upper surface of the fixed mold (3) is formed flat and a form in which the concave part (61) is formed in both the movable mold (2) and the fixed mold (3) are also desired shapes of the die cast product. -It can be adopted as appropriate according to the type. Further, in the figure, a single mold (2, 3) is shown, but it is also possible to use an additional mold depending on the desired shape and type of die-cast product. include.

In the example shown in FIG. 1A, the recess (61) is formed in a substantially rectangular shape in plan view, but the shape in plan view of the recess (61) is appropriately determined according to the shape of the desired die-cast product. It is done.
A packing groove is formed on the upper surface of the fixed mold (3) so as to surround the recess (61), and a heat-resistant packing (31) is arranged in the packing groove. When the movable mold (2) and the fixed mold (3) are clamped and pressed against each other, the heat-resistant packing (31) is compressed and deformed, and exhibits high sealing performance against the cavity (6). .

An injection port (34) connected to the main injector (4) is formed substantially at the center of the recess (61). Moreover, the opening part (35) connected to a subinjector (5) is formed in the corner | angular corner part of a recessed part (61).

As shown in FIG. 1B, the main injector (4) includes a cylindrical sleeve (41). An upper end portion (411) of the sleeve (41) is fixed to the fixed mold (3) to form an injection port (34).
The sleeve (41) extends downward from the lower surface of the fixed mold (3). An actuator is attached to the lower end (412) of the sleeve (41). In the example shown in FIG. 1, an electric servo cylinder (42) is used as the actuator.

A plunger tip (43) is disposed inside the sleeve (41). In the example shown in FIG. 1B, the upper part (431) and the lower part (432) of the plunger tip (43) are formed larger in diameter than the intermediate part (433) between the upper part (431) and the lower part (432). Is done. In the example shown in FIG. 1B, a gap of 0.05 mm or more and 0.1 mm or less is provided between the outer peripheral surface of the upper portion (431) of the plunger tip (43) and the inner peripheral surface of the sleeve (41). Further, a vacuum seal material (434) is disposed between the outer peripheral surface of the lower portion (432) of the plunger tip (43) and the sleeve (41), and the vacuum seal material (434) serves as the lower portion (432) of the plunger tip (43). It is compressed and deformed between the outer peripheral surface and the sleeve (41) and exhibits high hermetic sealing performance.

In the example shown in FIG. 1B, most of the rod (421) of the electric servo cylinder (42) is housed in the electric servo cylinder main body (422), and the rod of the electric servo cylinder (42). The plunger tip (43) connected to (421) is in the retracted position. In this specification, the retracted position does not mean the lower limit position of the mechanical operation range, but means the position where the plunger tip (43) is retracted from the cavity in the molding process. Since the plunger tip (43) is formed shorter than the sleeve (41), when the plunger tip (43) is at the lowest position, a space is formed on the upper portion of the sleeve (41). The heat insulating capsule (7) is disposed in the formed space. The heat insulating capsule (7) accommodates the molten metal therein and exhibits high heat insulating performance so as to prevent the temperature of the molten metal from decreasing.

A suction port (44) is provided inside the sleeve (41), and the suction port (44) is connected to a vacuum generator (not shown) such as a vacuum pump. When the vacuum generator is activated, the gas inside the die casting apparatus (1) is released to the outside of the die casting apparatus (1) through the suction port (44). As described above, since there is no cooling of the molten metal, a sufficient suction time can be secured, and in addition, a vacuum is formed between the lower portion (432) of the plunger tip (43) and the inner peripheral surface of the sleeve (41). Since the seal (434) is arranged and exhibits high hermetic sealing performance, a large amount of gas is sucked from the cavity (6), and the inside of the cavity (6) can be kept in a high vacuum state. Thereby, formation of the bubble in a die-cast product can be prevented suitably. As described above, the gas flows from the cavity (6) to the suction port (44). A heat insulating capsule (7) exists in the middle of the flow path of the gas body. Since the molten metal is held inside the heat insulating capsule (7), the molten metal is not sucked into the suction port by suction. Further, since the heat insulating capsule (7) exhibits high heat insulating performance, even if the heat insulating capsule (7) is exposed to this gas flow, the temperature of the molten metal inside the heat insulating capsule (7) is reduced. There is no. Furthermore, the molten metal is degassed under a high vacuum, and the molten metal can be cleaned.

FIG. 2 is an enlarged view of the sub-injector (5) shown in FIG. 1 (c). The sub injector (5) has substantially the same structure as the main injector (4). The sub-injector (5) includes a cylindrical sleeve (51). The upper end (511) of the sleeve (51) is fixed to the stationary mold (3), and the internal space of the sleeve (51) communicates with the cavity (6) through the opening (35). The sleeve (51) extends downward from the lower surface of the fixed mold (3). An actuator is attached to the lower end (512) of the sleeve (51). In the example shown in FIGS. 1 and 2, an electric servo cylinder (52) is used as the actuator.

A plunger tip (53) is disposed inside the sleeve (51). In the example shown in FIG. 1C and FIG. 2, the upper portion (531) and the lower portion (532) of the plunger tip (53) have a diameter larger than the intermediate portion (533) between the upper portion (531) and the lower portion (532). Largely formed.
In the example shown in FIGS. 1C and 2, a gap of 0.05 mm or more and 0.1 mm or less is provided between the outer peripheral surface of the upper portion (531) of the plunger tip (53) and the inner peripheral surface of the sleeve (51). It is done. Further, a vacuum seal material (534) is disposed between the outer peripheral surface of the lower portion (532) of the plunger tip (53) and the sleeve (51), and the vacuum seal material (534) serves as the lower portion (532) of the plunger tip (53). It is compressed and deformed between the outer peripheral surface and the sleeve (51) and exhibits high hermetic sealing performance.

A suction port (54) is provided inside the sleeve (51), and the suction port (54) is connected to a vacuum generator (not shown) such as a vacuum pump. When the vacuum generator is activated, the gas inside the die casting apparatus (1) is released to the outside of the die casting apparatus (1) through the suction port (54). As described above, the vacuum seal (534) is disposed between the lower portion (532) of the plunger tip (53) and the inner peripheral surface of the sleeve (51), and exhibits high hermetic sealing performance. A lot of gas is sucked, and the inside of the cavity (6) can be depressurized. Thereby, formation of the bubble in a die-cast product can be prevented suitably. In this embodiment, a decompression sensor is attached to at least one of the suction port (44) of the main injector (4) and the suction port of the sub-injector (5), and the degree of vacuum in the cavity (6) can be measured. is there.

The present inventor uses the die casting apparatus illustrated in FIGS. 1 and 2 to solidify with a refractory coating at low speed and low pressure (about 10 to 100 atm, plunger speed 0.1 to 0.5 m / s). By performing the control, an aluminum die casting method having a complex large shape and a thin shape, which will be described in detail below, was realized.

Referring to FIGS. 1 and 2, the die casting method of Embodiment 1 includes the following steps.
(Step 1) A movable mold (2) having a shape that defines a cavity (6) for molding a plurality of aluminum die-cast products having different thicknesses, and a mold composed of a fixed mold (3), the movable mold Opening process to open the mold by retreating,
(Step 2) After the mold opening step, the movable die (2) and the fixed die (3) that are in contact with the cavity at a thickness corresponding to each thickness of the different thickness of the aluminum die cast product. Forming a heat insulating film (not shown) on the surface;
(Step 3) A space in the sleeve (51) generated by retreating the plunger tip (53) disposed in the sleeve (51) of the main injector communicating with the cavity (6) in the sleeve (51) A capsule housing step for housing the heat-insulating capsule (7) in which the molten metal is held,
(Step 4) After the capsule housing step, the movable mold (2) is moved in the direction of the fixed mold (3) to clamp the mold, and
(Step 5) a vacuum step for reducing the pressure in the cavity (6);
(Step 6) After the mold closing step, the plunger tip (53) is advanced toward the cavity (6) in the sleeve (51), and the capsule (7) is moved into the cavity (6). An injection step of moving and destroying (smashing) the capsule (7) to fill the cavity with the molten metal held in the capsule (7);
(Step 7) Pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity (6);
(Step 8) An extrusion step of extruding the die-cast product formed by solidifying in the cavity (6) after separating the movable mold (2) and the fixed mold (3).
In the die casting method according to the present embodiment, the movable die (2) and the fixed die that are in contact with the cavity (6) at a thickness corresponding to each thickness of the different thicknesses of the aluminum die cast product. Before the step of forming the heat insulation film on the surface of the mold (3), the method includes a step of subjecting the inner surfaces of the movable mold (2) and the fixed mold (3) to shot.
Further, a heat insulating coating is formed on the surfaces of the movable mold (2) and the fixed mold (3) in contact with the cavity (6) at a film thickness corresponding to each thickness of the different thicknesses of the aluminum die cast product. Forming a metal sprayed film on the inner surfaces of the movable mold (2) and the fixed mold (3), and performing ceramic spraying on the metal sprayed film to form a ceramic sprayed film. The step of forming a heat insulating film is preferable.

That is, in this embodiment,
Performing a shot on the surface of the mold (2, 3) (for example, SKD61 material) to improve the adhesion of the underlying metal spray film;
It includes a step of forming a metal sprayed film that functions as a base.
As the metal sprayed film, for example, a Ni—Cr system (film thickness of 50 μm) is suitable, and adhesion and thermal shock properties are improved. Next, a ceramic sprayed film serving as a surface layer is formed on the metal sprayed film. As the ceramic sprayed film, for example, a zirconia-based, calcia-based, or alumina-based ceramic (thickness: 50 to 300 μm) is preferably employed. Sufficient strength, durability, and heat retention can be obtained by a low-speed and low-pressure die casting process using such a two-layer mold heat insulation film (hereinafter also referred to as a heat insulation film). Moreover, in order to improve mold release property, it can be used in combination with a conventional mold release agent. However, as described above, it is difficult to apply the conventional process to high-speed and high-pressure die casting from the viewpoint of durability and releasability.

Here, using this two-layer mold heat insulation film, for example, an application example will be described where the thickness of an aluminum die-cast product is 5 mm at the maximum and has different thicknesses of 3 mm, 2 mm, and 1,5 mm.

In the die casting method of the present embodiment, the solidification time of the thickness of each part of the aluminum die cast product is 0.1 seconds, 0.06 seconds, 0.02 seconds, and 0.01 seconds, respectively (see FIG. 9). .

Thus, since the solidification time of the thickness of each part of an aluminum die-cast product is different, solidification progresses unless the filling is completed within 0.01 seconds, which is the fastest solidification, resulting in poor hot water. In addition, in order to prevent shrinkage defects at the time of solidification of a 5 mm portion that is slow to solidify, it is necessary to change the plan and thickness so that pressure is propagated and directional solidification occurs. That is, high-speed injection (filling must be completed within 0.01 seconds (for example, increase in moving speed of the plunger (5-10 m / s)) in order to prevent poor hot water in the thinnest part. In addition, a high pressure (for example, 500 to 1000 atm) is required to prevent shrinkage defects in the thick-walled portion, but it is difficult to propagate the pressure to the slowly solidified portion only by increasing the pressure, and the pressure propagation path It may be necessary to increase the thickness of the thin-walled portion in order to secure the thickness, and it may not be possible to secure the thin-walled / lightweight. In other words, the conventional die casting method requires a high-speed and high-pressure die-casting device, and in some cases, it is necessary to increase the thickness, install a pressure pin, etc., making it difficult to reduce the weight. For embodiments, when the maximum thickness of a 5 mm, subjected to a thermal insulation coating it from a thin portion of the thickness, extend the coagulation time.

For example, a 50 μm coating is applied to a 3 mm thick part, a 100 μm coating is applied to a 2 mm thick part, and a 200 μm coating is applied to a 1.5 mm thick part. By this coating treatment, the solidification time of each part having a thickness of 5 to 1.5 mm is the same as 0.1 second. Accordingly, it is sufficient that the filling time is 0.1 seconds or less, 0.1 seconds with respect to the conventional filling time of 0.01 seconds, and an injection speed of 1/10 is sufficient.

Also, the solidification time is 0.1 seconds for the entire thick part, and considering the temperature drop from the injection part, solidification in the far part is relatively fast, solidification is slow in the near part, and directional solidification occurs. It becomes possible and shrinkage defects will not occur. That is, it is not necessary to pressurize with high pressure.

From the above, by performing solidification control with the two-layer coating (mold heat insulation coating), it becomes possible to die-cast a complex large-sized product having a large change in thickness and thickness at a low speed and a low pressure. In addition, the use of multiple injection plungers, which is the point of the process of this embodiment, reduces the required filling and pressurizing range for each plunger, and also enables the injection speed and injection pressure to be reduced. It is.

The procedure for applying the die casting method of the present embodiment to an actual die casting product is as follows (see FIG. 10; two injection plungers).
(I) The thickest part is examined (for example, thickness t = 10 mm).
(Ii) The thickness of the coating is determined so that the coagulation times are the same for the thinner parts (t = 5, t = 4, t = 3, t = 2 mm) (from FIG. 11, 50 and 75). , 100, 210 μm).
(Iii) The injection speed is determined so that the thickest part can be filled within the solidification time (within 0.2 seconds).

[Embodiment 2]
The present embodiment is different from the first embodiment in the following steps of the first embodiment.
(Step 3) A space in the sleeve (51) generated by retreating the plunger tip (53) disposed in the sleeve (51) of the main injector communicating with the cavity (6) in the sleeve (51) A capsule housing step of housing the heat-insulating capsule (7) in which the molten metal is held.
(Process 4) A closed mold process in which the movable mold (2) is moved in the direction of the fixed mold (3) and clamped after the capsule housing process.
(Step 5) A vacuum step for reducing the pressure in the cavity (6).
(Step 6) After the mold closing step, the plunger tip (53) is advanced toward the cavity (6) in the sleeve (51), and the capsule (7) is moved into the cavity (6). An injection step of moving and destroying (smashing) the capsule (7) to fill the cavity with the molten metal held in the capsule (7).

That is, in this embodiment,
(Step 3) A thin film heat insulating material molded into a cylindrical shape is inserted into a space in the sleeve generated by retreating a plunger tip disposed inside the sleeve of the main injector communicating with the cavity, Pouring molten metal into the cylindrical thin film heat insulating material;
(Step 4) In the above step, after the pouring of the molten metal using the handle (D) is completed, the mold is closed by moving the movable mold in the direction of the fixed die ((a) of FIG. 3). reference),
(Step 5) a vacuum step for reducing the pressure in the cavity;
(Step 6) After the mold closing step, the plunger tip is advanced toward the cavity in the sleeve to move the cylindrical thin film heat insulating material filled with the molten metal to the cavity. And an injection step of filling the cavity with the molten metal held in the thin film heat insulating material.

For example, the following steps (1) to (4), that is,
Step (A1): Prepare ceramic paper (for example, making paper from alumina / silica fiber and a small amount of binder, 200 mm × 300 mm × 0.2 mm),
Step (A2): A ceramic paper is wound around a cylindrical jig (for example, outer diameter 99.5φ), and the upper end is bent.
Step (A3): The ceramic paper is temporarily attached with an adhesive aluminum tape, and a bottomed cylindrical heat insulating material (inner diameter 99.0φ, outer diameter 100φ) having an open top is molded as a molded body.
Step (A4): including sliding a part of the columnar jig to reduce the diameter of the columnar jig and taking out the cylindrical heat insulating material.
In the manufacturing process of the cylindrical thin film heat insulating material, the excess amount of the liquid lubricant is absorbed by the ceramic paper, does not react with the molten metal, and can be kept clean. Of course, necessary and sufficient lubricant remains in contact with the inner wall of the injection sleeve (41) and the plunger (53) (see FIG. 1), and sufficient lubricity is ensured. That is, the thin film heat insulating material is effective at two points of molten metal heat retention and melt cleanliness by non-contact with the lubricant.

When pouring a molten aluminum at about 700 ° C., it is expected that the adhesive strength of the aluminum adhesive tape will disappear. However, the molten aluminum is in direct contact with the aluminum adhesive tape because it is via a thin film heat insulating material. Therefore, the function can be sufficiently achieved in a short time (about several tens of seconds) from pouring to injection. Therefore, there is an advantage that a highly accurate cylindrical heat insulating material can be easily molded by a simple process without using a heat-resistant adhesive. In addition, since the aluminum adhesive tape has rigidity, there is an advantage that the shape of the thin film cylinder can be maintained. Since the aluminum adhesive tape is made of pure aluminum, there is also an advantage that there is no adverse effect as an impurity when the biscuit part after the injection is remelted and regenerated. In the present invention, other than the aluminum adhesive tape, an adhesive tape, an adhesive, a double-sided adhesive tape, and the like can also be used.

Referring to FIG. 3, the thin film heat insulating material (C), which is a molded body obtained by the step (3), is flexible. Therefore, by crushing a part of the thin film heat insulating material (C), the thin film heat insulating material (C) The outer diameter of C) is slightly shrunk and inserted into the injection sleeve (41), and the thin film heat insulating material (C) can be brought into close contact with the inner wall of the injection sleeve (41) with a smoothing plate. At that time, since there is an aluminum adhesive tape, it is useful for maintaining the shape of a 0.2 mm thick ceramic paper. Through the above steps, the fragile thin film molded body (C) can be easily adhered in a short time to the inner wall of the injection sleeve (IS) (the thin film heat insulating material (C)).

By the method described above, the fragile thin film heat insulating material (C) can be adhered to the inner wall of the injection sleeve (41). Preferably, a liquid chip lubricant (L) is already applied in the injection sleeve (41), but the amount is very small, and a part of the injection sleeve (41) is absorbed by the thin film heat insulating material (C). The original lubrication function can be achieved without contact. Normally, the lubricant comes into direct contact with the molten aluminum and bumps or gets caught in the molten metal, which contaminates the molten metal. It is possible to produce high-quality aluminum die-cast products that are maintained without being lowered.
Also, the heat insulating material that has been tightly held on the inner wall by the molten metal pressure is compressed and broken (crushed) like a lantern on the inner wall during injection, and remains in the sleeve and does not break, so it flows into the product cavity. There is no. Therefore, a high-temperature and highly clean molten metal is injected into the product cavity.

[Embodiment 3]
The present embodiment is different from the first embodiment in the following steps of the first embodiment.
(Step 3) A space in the sleeve (51) generated by retreating the plunger tip (53) disposed in the sleeve (51) of the main injector communicating with the cavity (6) in the sleeve (51) A capsule housing step of housing the heat-insulating capsule (7) in which the molten metal is held.
(Process 4) A closed mold process in which the movable mold (2) is moved in the direction of the fixed mold (3) and clamped after the capsule housing process.
(Step 5) A vacuum step for reducing the pressure in the cavity (6).
(Step 6) After the mold closing step, the plunger tip (53) is advanced toward the cavity (6) in the sleeve (51), and the capsule (7) is moved into the cavity (6). An injection step of moving and destroying (smashing) the capsule (7) to fill the cavity with the molten metal held in the capsule (7).

That is, in this embodiment, referring to FIGS.
(Step 3) A space in the sleeve (51) generated by retreating the plunger tip (53) disposed in the sleeve (51) of the main injector communicating with the cavity (6) in the sleeve (51) And a housing step of injecting molten metal (MA) from the gap between the movable mold (2) and the fixed mold (1),
(Step 4) After the pouring of the molten metal (MA) is completed in the step, the movable mold (2) is moved in the direction of the fixed mold (1), and the movable mold (2) and the fixed mold ( 1) is held for a predetermined time (for example, <3 + 1 seconds>) in a slightly opened state;
(Step 5) a vacuum step for reducing the pressure in the cavity (6);
(Step 6) After reaching the high vacuum after the step, the movable die (2) and the fixed die (1) are completely closed, and then the plunger tip (53) is placed in the sleeve (51). And an injection step of filling the cavity (6) with the molten metal (MA) by advancing toward the cavity (6).
And in this embodiment, without using a special heat insulating material by the steps 3 to 6, a special method such as a tilting sleeve method, a baculal method (vacuum suction method), a low pressure pouring method (MP method), etc. There is no need for a pouring mold mechanism, and there is no need for an expensive vacuum valve or chill vent. By holding the closing stroke of the mold in three stages: half-open, slightly open, and front-close, the vertical die casting method Can easily produce large and thin products at low speed and low pressure.

[Embodiment 4]
In the die casting method of the fourth embodiment, in the step 2 of each of the first to third embodiments, the step of forming a heat insulating film (not shown) on the surfaces of the movable mold (2) and the fixed mold (3) is as follows. It comprises steps (i) to (vi).
Step (i): A molten metal flow solidification simulation is performed to find a site where solidification is slow. (If possible, it is better to make the site with slow coagulation close to the gate. Note that the injection speed is increased and decreased so that the filling time is shorter than the coagulation time of the site with slow coagulation.)
Step (ii): The thermal insulation film thickness is determined so that the coagulation time is the same as the coagulation time from FIG.
Step (iii): The thermal resistance value is obtained from the correlation diagram (FIG. 11) between the film thickness and the thermal resistance value, and the molten metal flow solidification simulation is performed again using the value.
Step (iv): Confirm that each part of the die cast product to be molded has substantially the same solidification time.
Step (v): If there is a part where the coagulation time is different, the thermal resistance value is increased or decreased, the coagulation time is confirmed, and further changed to be directional coagulation. (In this case, since there is a temperature drop of the molten metal during filling, the part farther from the injection part is quickly solidified and the part near is slowed, but the thermal resistance value can be further modified to improve the degree of directional solidification. Is possible)
Step (vi): The film thickness is determined from the optimum thermal resistance value obtained by the simulation of the step (iii), and the coating treatment is applied to the mold.
In the case of a relatively simple shape, the film thickness can be determined by the simple method disclosed in Embodiment 1, but in the case of a complicated shape, the method disclosed in Embodiment 2 utilizing computer simulation. Can determine the film thickness.

By the above steps (i) to (vi), a non-defective product can be obtained under optimum injection conditions. By the above method, a complex and large die-cast product with a change in wall thickness can be easily manufactured by this process.

According to the die casting method of the present invention, even if a product to be molded that does not have a uniform thickness has a large and complicated shape, die casting can be performed by performing solidification control using a mold heat insulating coating. it can.

DESCRIPTION OF SYMBOLS 1 ... Die casting apparatus 100 ... Die casting product 2 ... Movable metal mold 3 ... Fixed metal mold 4 ... Main injector 41 ... Sleeve 42 ... · Electric servo cylinder 43 ··· Plunger tip 44 · · · Suction port 5 · · · Sub-injector 51 · · · Sleeve 52 · · · Electric servo cylinder 53 · · · Plunger tip 54 · · · ..Suction port

Claims (10)

(1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) Capsule housing step of housing a heat-insulating capsule in which a molten metal is held in a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity in the sleeve When,
(4) a closed mold step of clamping the mold by moving the movable mold in the direction of the fixed mold after the capsule housing step;
(5) a vacuum process for reducing the pressure in the cavity;
(6) After the mold closing step, the plunger tip is advanced in the sleeve toward the cavity, the capsule is moved to the cavity, the capsule is broken, and the molten metal held in the capsule is removed. An injection process for filling the cavity;
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) A die casting method comprising: an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold. (1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) A thin-film heat insulating material molded into a cylindrical shape is inserted into a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity, and A process of pouring molten metal into a cylindrical thin film heat insulating material;
(4) In the above step, after completion of pouring of the molten metal, a closed mold step of clamping the mold by moving the movable mold in the direction of the fixed mold,
(5) a vacuum process for reducing the pressure in the cavity;
(6) After the mold closing step, the plunger tip is advanced toward the cavity in the sleeve, and the cylindrical thin film heat insulating material filled with the molten metal is moved to the cavity. An injection step of breaking the thin film heat insulating material and filling the cavity with the molten metal held in the thin film heat insulating material,
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) A die casting method comprising: an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold. (1) a mold opening step for opening a mold including a movable mold and a fixed mold having a shape that defines a cavity for molding a plurality of aluminum die-cast products having different thicknesses by retracting the movable mold; ,
(2) After the mold opening step, a heat insulating coating is formed on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the plurality of different thicknesses of the aluminum die cast product. Forming, and
(3) A space between the movable die and the fixed die is formed in a space in the sleeve generated by retreating a plunger tip disposed in the sleeve of the main injector communicating with the cavity. A housing process for injecting molten metal;
(4) After completion of pouring of the molten metal in the step, the movable mold is moved in the direction of the fixed mold, and the movable mold and the fixed mold are held in a state of being opened for a predetermined time. Process,
(5) a vacuum process for reducing the pressure in the cavity;
(6) After reaching the high vacuum after the step, the movable die and the stationary die are completely closed, and then the plunger tip is advanced toward the cavity in the sleeve, An injection process for filling the cavity with molten metal;
(7) A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
(8) A die casting method comprising: an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold. Before the step of forming a heat insulation film on the surfaces of the movable mold and the fixed mold in contact with the cavity at a thickness corresponding to each thickness of the different thicknesses of the aluminum die cast product, the movable mold The die casting method according to any one of claims 1 to 3, further comprising a step of performing shot scoring on an inner surface of the mold and the fixed mold. The step of forming a heat insulation film on the surface of the movable mold and the fixed mold in contact with the cavity at a film thickness corresponding to each thickness of the different thickness of the aluminum die cast product includes the movable mold and The metal sprayed film is formed on the inner surface of the fixed mold, and the ceramic sprayed film is formed on the metal sprayed film to form a ceramic sprayed film, thereby forming a heat insulating film. The die casting method according to any one of 1 to 4. The die casting method according to claim 5, wherein the metal sprayed film has a thickness of about 50 μm. The die casting method according to any one of claims 1 to 6, wherein the metal sprayed film is a Ni-Cr system. 8. The die casting method according to claim 5, wherein the ceramic sprayed film has a thickness of about 5 to 300 [mu] m. 9. The die casting method according to claim 5, wherein the ceramic sprayed film is zirconia-based, calcia-based, or alumina-based. Forming a heat insulation film on the surfaces of the movable mold and the fixed mold,
(I) performing a hot water flow solidification simulation and determining a site where solidification is slowest;
(Ii) determining the film thickness of the thermal insulation film so as to have the same solidification time as the latest solidification time determined by the above-mentioned steps;
(Iii) a step of determining a thermal resistance value from the correlation between the film thickness and the thermal resistance value, and again performing a molten metal flow solidification simulation with the determined thermal resistance value;
(Iv) confirming that the coagulation time of each part of the product to be molded is substantially the same coagulation time;
(V) if there is a part where the coagulation time is different in the step (iv), a step of increasing or decreasing the thermal resistance value, confirming the coagulation time, and further changing to become directional coagulation;
(Vi) determining an optimum film thickness of the coating layer from an optimum thermal resistance value obtained by the simulation of the step (iii), and applying a coating treatment to the mold with the optimum film thickness; The die casting method according to any one of claims 1 to 9, characterized by comprising: