JP3620476B2 - Die casting machine injection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection device for a die-casting machine, and in particular, from a molten metal holding furnace after preliminarily vacuuming a cavity that functions as a product shape portion space and an injection sleeve communicating therewith prior to a molten metal injection operation. The present invention relates to an injection apparatus for a die casting machine in which a molten metal is transferred to an injection sleeve using a vacuum pressure.
[0002]
[Prior art]
As an injection device of this type of die casting machine, for example, those described in Japanese Patent No. 264588 and Japanese Patent Laid-Open No. 57-152361 are known.
[0003]
FIG. 2 schematically shows a cavity (product shape portion space) formed by a fixed mold 52 fixed to a fixed platen 51 and a movable mold (not shown) in a horizontal cold chamber die casting machine. In order to inject and fill the molten metal, a horizontal injection sleeve 53 is connected to the fixed mold 52, and a hot water stalk 54 connected to the rear end of the injection sleeve 53 faces the molten metal holding furnace 55 below. It is. An injection piston 56 is inserted and supported in the injection sleeve 53 so as to be movable back and forth, and a heat-resistant packing 57 is provided on the inner periphery of the rear end portion of the injection sleeve 53. As shown in FIG. In the state where 56 is in the last retracted position, the inside and outside of the injection sleeve 53 are sealed by pressure contact with the packing 57.
[0004]
Then, the cavity and the inside of the injection sleeve 53 are evacuated while the injection piston 56 is in the last retracted position as shown in the figure, and the molten metal M in the molten metal holding furnace 55 is given a predetermined amount by the vacuum pressure. Then, the molten metal M is filled in the cavity by the subsequent forward movement of the injection piston 56. In addition, the vacuum said here is a pressure below 100 mbar. The hot water supply stalk 54 shown in FIG. 2 is firmly fixed to the injection sleeve 53 with a stalk holder 58 and a set screw 59.
[0005]
Further, in Japanese Utility Model Publication No. 3-37812 in addition to the above-mentioned Japanese Patent Application Laid-Open No. 57-152361, as shown in FIG. 3, it is formed on the piston rod 62 in order to stabilize the degree of vacuum particularly in the vicinity of the injection piston 61. A technique is described in which the vacuum passage 63 is extended to the injection piston 61 side and the opening end 64 is opened in an annular groove 65 formed on the outer peripheral surface of the injection piston 61 itself. The injection piston 61 has a cooling water passage 66 and a cooling hole 67 communicating therewith.
[0006]
[Problems to be solved by the invention]
In such a conventional technique, the packing 57 that seals between the injection sleeve 53 and the injection piston 56 has heat resistance, but it is used under severe conditions. For example, as the injection piston 56 repeats reciprocating operation, the cast burr that has entered between the injection sleeve 53 and the injection piston 56 can be easily inserted into the packing 57, resulting in deteriorated sealing performance and an early life of the packing 57 itself. There is a drawback that it is easy.
[0007]
In the latter case, an annular groove 65 is formed on the outer peripheral surface of the injection piston 61 so that a positive vacuum is applied to the outer peripheral surface of the injection piston 61. It is difficult to maintain the original evacuation function stably for a long time due to clogging or the like, and it is difficult to maintain the original vacuuming function for a long time due to clogging. ing.
[0008]
The present invention has been made paying attention to such a conventional problem, and is based on the assumption that sealing between the injection sleeve and the injection piston with a sealing member such as packing, particularly by inserting or depositing a cast beam. An object of the present invention is to provide a structure that prevents functional deterioration and maintains a stable vacuum state over a long period of time.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a horizontal injection sleeve whose front end communicates with a cavity on the mold side, and a stalk that is connected to the rear end of the injection sleeve and has a lower end facing the molten metal holding furnace, An injection piston inserted in the injection sleeve so as to be movable back and forth, and the cavity and the injection sleeve are evacuated to suck and store the molten metal in the molten metal holding furnace on the injection sleeve side through the stalk. Thus, it is assumed that the injection device is a die casting machine in which the molten metal is filled into the cavity by the forward injection operation of the injection piston.
[0010]
Then, a vacuum chamber having a sealed structure having an inner diameter larger than that of the injection sleeve is formed so as to extend to the rear end side of the injection sleeve, and the vacuum chamber is connected to a vacuum source. The sealing member provided on the rear wall side seals between the outer peripheral surface of the rear end portion of the injection piston and the corresponding rear wall on the vacuum chamber side at the last retracted position of the injection piston. It is characterized by.
[0011]
In this case, it is desirable that the injection piston is always cooled by a known method such as a forced cooling method using a flow of cooling water.
[0012]
Furthermore, as in the invention described in claim 2, the diameter of the outer peripheral surface of the rear end portion of the injection piston to be sealed by the sealing member is formed smaller than the diameter of the general portion of the injection piston. Is desirable.
[0013]
Therefore, in the first aspect of the invention, the injection piston that repeatedly injects the molten metal becomes hot at the front end surface side that is in direct contact with the molten metal, but the injection sleeve is extended to the rear side. A vacuum chamber is formed so that a seal is provided between the sealing member provided on the rear wall of the vacuum chamber and the rear end portion of the injection piston when it returns to the last retracted position. As a result, the injection piston The distance from the front end surface to the rear end is longer than the conventional one. Moreover, in consideration of the fact that the injection piston itself is generally forcibly cooled at all times by the flow of cooling water or the like, the temperature rise of the rear end portion of the injection piston becomes relatively slow. As a result, the seal member that contacts the rear end of the injection piston and controls the seal, such as a rubber packing made of nitrile rubber or fluorine rubber, etc., which has been unable to be used conventionally, is used Thus, a stable vacuum state can be maintained by improving the sealing performance.
[0014]
In addition, by making the vacuum chamber larger in diameter than the injection piston, this vacuum chamber can also function as a space for storing the flash that has been taken out of the injection sleeve by the injection piston. There is no need to insert the sealing member into the sealing member to lower the sealing performance or to clog the vacuum passage.
[0015]
In particular, when the diameter of the outer peripheral surface of the rear end portion of the injection piston is smaller than the diameter of the general portion of the injection piston as in the invention described in claim 2, the seal is brought about by contact with the seal member as described above. The outer peripheral surface of the rear end of the injection piston that controls the injection sleeve is no longer in direct contact with the inner peripheral surface of the injection sleeve, making it less susceptible to thermal effects from the injection sleeve side and more secure insertion of the casting Will be able to prevent.
[0016]
【The invention's effect】
According to the first aspect of the present invention, since the thermal conditions of the rear end portion of the injection piston and the seal member that govern the sealing of the vacuum degree of the injection sleeve are alleviated, the seal member with high sealing performance In addition to being able to maintain a stable vacuum state for a long period of time by adopting, etc., there is an effect of preventing the deterioration of the sealing performance due to insertion of a cast beam or the like and improving the durability of the sealing member.
[0017]
According to the second aspect of the present invention, since the outer peripheral surface of the rear end portion of the injection piston that controls the seal is not in direct contact with the injection sleeve due to the contact with the seal member, the thermal condition is alleviated. As a result, the stability of the vacuum state, the durability of the sealing member, and the like are further improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing a preferred embodiment of an injection apparatus for a die casting machine according to the present invention, and shows the structure of the same portion as FIG. 2 with the injection piston in the last retracted position.
[0019]
As shown in FIG. 1, a horizontal injection sleeve 2 is supported on a stationary platen 1 so as to communicate with a cavity as a product shape portion (not shown). The hot water supply stalk 4 connected via the stalk 3 is fixedly supported by the stalk holder 5, the clamp bolt 6 and the lock nut 7, and the injection piston 8 is inserted into the injection sleeve 2 so as to be movable back and forth. The points and the like are the same as those shown in FIG. A clearance of, for example, about 0.05 to 0.5 mm is secured between the injection sleeve 2 and the injection piston 8 in consideration of thermal expansion and the like, and the hot water supply stalk 4 is disposed on the outer periphery thereof. The stalk heater 9 is maintained at a predetermined temperature.
[0020]
A closed vacuum chamber 10 having a circular cross section is concentrically fixed and supported at the rear end of the injection sleeve 2 so that the injection piston 8 is in the last retracted position P. Penetrates the vacuum chamber 10.
[0021]
The vacuum chamber 10 has a bottomed cylindrical front cover 11 and a rear cover 12 that face each other and are detachably coupled with a joint 13 by a so-called flange joint system. The inner diameter of the vacuum chamber 10 is the inner diameter of the injection sleeve 2. The front cover 11 is fixed to the rear end surface of the injection sleeve 2 with bolts 14. The vacuum chamber 10 is connected to a predetermined vacuum source 16 such as a vacuum pump via a pipe 15.
[0022]
Here, since the vacuum heat insulation effect can be expected as the volume of the vacuum chamber 10 increases, it is desirable that the size of the vacuum chamber 10 is large enough not to interfere with peripheral devices. Since it will take time, it should be set to an appropriate size.
[0023]
The front cover 11 and the rear cover 12 are formed with holes 17 or 18 through which the injection piston 8 passes. Although the diameter of the hole 17 on the front cover 11 side is formed larger than that of the injection piston 8, the diameter of the hole 18 formed in the rear wall portion 12a of the rear cover 12 is the rear end portion of the injection piston 8 described later. A rubber ring-shaped seal packing 19 such as nitrile rubber or fluorine rubber is attached to the inner periphery of the hole 18 as a sealing member having excellent sealing performance. ing. The seal packing 19 is pressed and fixed from the outside by a bolt-fixing holding plate 20.
[0024]
On the other hand, the injection piston 8 is formed integrally with the piston rod 21 having a smaller diameter, and the front half of the injection piston 8 has a diameter that can be inserted into the injection sleeve 2, whereas the rear end The portion 8a has a smaller diameter than the front half and is set to a size that can be inserted into the hole 18 on the vacuum chamber 10 side, and has the smallest diameter between the front half and the rear end 8a of the injection piston 8. Such a circumferential groove 8b is formed. As shown in FIG. 1, when the injection piston 8 is in the last retracted position P, the front half does not completely come out of the injection sleeve 2 and the outer peripheral surface of the rear end 8 a is pressed against the seal packing 19. The vacuum chamber 10 is sealed with the seal packing 19 so as to form a completely sealed structure.
[0025]
Further, the injection piston 8 and the piston rod 21 are formed with cooling holes 22 through which predetermined cooling water flows, and the injection piston 8 is forcibly cooled.
[0026]
In addition to the joint between the hot water supply stalk 4 and the base 3, the joint between the injection sleeve 2 and the front cover 11 and the joint between the front cover 11 and the rear cover 12 are each provided with a heat-resistant packing such as a carbon gasket (not shown). It is interposed and sealed with this heat-resistant packing.
[0027]
Therefore, according to the injection apparatus configured as described above, the cavity on the mold side communicating with the injection sleeve 2 is in a vacuum state with the injection piston 8 in the most retracted position P as shown in FIG. In addition, the vacuum chamber 10 is also brought into a vacuum state by the vacuum source 16. In this case, since a minute clearance is secured between the injection sleeve 2 and the injection piston 8, as a result, the vacuum chamber 10 communicates with the cavity via the injection sleeve 2, and both are predetermined. The pressures are balanced with each other with the degree of vacuum.
[0028]
When the inside of the injection sleeve 2 reaches a predetermined degree of vacuum, the molten metal in the molten metal holding furnace is sucked up via the hot water supply stalk 4 and supplied into the injection sleeve 2 as in FIG. When a predetermined amount of molten metal is supplied to the injection sleeve 2, the injection piston 8 immediately moves forward to inject and fill the molten metal in the injection sleeve 2 into the cavity. Simultaneously with the forward movement of the injection piston 8, evacuation on the vacuum chamber 10 side is released, and the injection piston 8 is separated from the seal packing 19, so that the inside of the vacuum chamber 10 is opened to the atmosphere. Thereby, it is possible to prevent a part of the molten metal from flowing into the vacuum chamber 10 side.
[0029]
Further, only the front half of the injection piston 8 is in direct contact with the inner peripheral surface of the injection sleeve 2 and the molten metal during the forward movement of the injection piston 8, and the rear end 8a having a smaller diameter is not in contact at all.
[0030]
When the injection piston 8 moves forward to the most advanced position and the injection and filling of the molten metal are completed, the injection piston 8 returns to the state shown in FIG. 1 again, and the vacuum chamber 10 is moved by the pressure contact between the rear end portion 8a and the seal packing 19. The sealed state is set again, and thereafter, the same operation as described above is repeated for each shot.
[0031]
As the injection piston 8 repeats moving forward and backward in this manner, the injection piston 8 and the seal packing 19 also repeat pressing and separation, but as described above, Since the end portion 8a does not contact the inner peripheral surface of the injection sleeve 2 or directly contacts the molten metal, no casting is inserted into the seal packing 19, and the original sealing performance is maintained for a long time. become able to.
[0032]
In addition, the rear end portion 8a of the injection piston 8 that is in pressure contact with the seal packing 19 is separated from the piston front end surface that is in direct contact with the molten metal, and the injection piston 8 itself is forcibly cooled. Therefore, the temperature rise at the rear end portion 8a of the injection piston 8 becomes slow, and the thermal influence on the seal packing 19 can be suppressed. As a result, even if a rubber seal is used as the seal packing 19, there is no deterioration due to heat, and the original sealing performance and thus the vacuum degree of the vacuum chamber 10 can be maintained in a stable state.
[0033]
Furthermore, even if the molten metal that has entered between the injection sleeve 2 and the outer peripheral surface of the front half of the injection piston 8 becomes a flash and is brought to the last retracted position P of the injection piston 8 as shown in FIG. Since the cast beam falls into the vacuum chamber 10 and is recovered, the sealing performance and the like are not affected.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional explanatory view of a main part showing a preferred embodiment of the present invention.
FIG. 2 is a cross-sectional explanatory view of an essential part showing an example of a conventional injection apparatus.
FIG. 3 is an explanatory view showing another example of a conventional injection piston.
[Explanation of symbols]
2 ... Injection sleeve 4 ... Hot water supply stalk 8 ... Injection piston 8a ... Rear end 10 ... Vacuum chamber 11 ... Front cover 12 ... Rear cover 12a ... Rear wall 16 ... Vacuum source 19 ... Seal packing (seal member)
P: Last exit position

Claims (2)

A horizontal injection sleeve whose front end communicates with the cavity on the mold side, stalk which is connected to the rear end of this injection sleeve and whose lower end faces the molten metal holding furnace, and can move forward and backward in the injection sleeve With an inserted injection piston,
The cavity and the injection sleeve are evacuated so that the molten metal in the molten metal holding furnace is sucked and stored on the injection sleeve side through the stalk, and then the molten metal is filled into the cavity by the forward injection operation of the injection piston. In the die casting machine injection device,
Forming a vacuum chamber with a sealed structure having an inner diameter larger than that of the injection sleeve so as to extend to the rear end side of the injection sleeve,
Connect this vacuum chamber to a vacuum source,
A seal member provided on the rear wall side seals between the outer peripheral surface of the rear end portion of the injection piston and the corresponding rear wall on the vacuum chamber side at the last retracted position of the injection piston. Die-cast machine injection device. 2. The die casting machine according to claim 1, wherein the diameter of the outer peripheral surface of the rear end portion of the injection piston to be sealed by the seal member is smaller than the diameter of the general portion of the injection piston. Injection device.

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