JPH0683139U - Gravity mold casting equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a gravity die casting apparatus that accelerates the solidification rate of the upper part of the riser without causing shrinkage cavities in the product, thereby shortening the casting cycle. [Structure] A cylindrical heat retaining lining 23 that is integrally fitted to a mold 21 that forms the casting space 16 and forms a riser space 22 that communicates with the casting space 16, and is provided on the upper outer periphery of the heat retaining lining 23. Being warm insulation lining 23
Cooling means 24 for promoting heat radiation of the upper outer periphery of the.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gravity mold casting apparatus for injecting molten metal into a mold that can be repeatedly used only by gravity, and is particularly suitable for application to a piston of an internal combustion engine.

[0002]

[Prior art]

 Gravity die casting equipment, like sand casting equipment, injects molten metal by gravity only to make products.However, since a metal mold is repeatedly used, aluminum alloys with a relatively low melting point are used. It is particularly effective when used for large-scale production of pistons and intake manifolds of internal combustion engines.

By the way, not only in the gravity die casting apparatus described above, but also in the casting process, a large volume shrinkage occurs when the molten metal solidifies, so that a shrinkage cavity may be formed in the cast product. In order to avoid such inconvenience, in general, a riser space corresponding to the shape of the product and communicating with the casting space is formed in the upper part of the mold, and the volumetric contraction of the molten metal injected into the casting space is suppressed. I am trying to compensate by moving. In other words, by setting the rate of solidification of the molten metal in the feeder space to be slower than that of the casting space, the position where the shrinkage cavity is formed is stopped at the portion of the feeder and care is taken not to form a shrinkage cavity on the product side. There is.

For example, in a gravity die casting machine, a metal such as gray cast iron, which has better heat dissipation than foundry sand, is used as a mold, so that it is necessary to improve the heat retention of the molten metal in the feeder space. As disclosed in Japanese Patent Laid-Open No. 3-911139, etc., a riser space is surrounded by a heat retaining lining formed of a porous ceramic having a small thermal conductivity, and the solidification rate of the melt in the riser space is high. I am trying to slow down.

[0005]

[Problems to be solved by the device]

 When a piston material for an internal combustion engine is manufactured using the gravity die casting apparatus disclosed in Japanese Utility Model Laid-Open No. 3-911139, etc., the side surface shape of the piston material after casting is shown in FIG. 3 shows. That is, the riser 3 is formed in the central portion of the top surface 2 of the piston material 1, and this riser 3 part is formed when the piston material 1 is post-processed as shown by the chain double-dashed line in FIG. The center boss 4 that serves as the reference is turned. Further, on the top surface 2 of the piston material 1, a plurality of escape portions 5 (four in the illustrated example) associated with the opening operation of an intake / exhaust valve (not shown) are formed with the feeder 3 interposed therebetween. Since the escape portion 5 does not require mechanical post-processing, it is formed in advance when the piston material 1 is cast.

In order to increase the production efficiency of such a piston material 1, if the casting cycle is shortened, the solidification of the upper part of the riser 3 surrounded by the heat insulation lining is not completely completed, so that the predetermined shape is obtained. Since the center boss 4 cannot be processed, it is substantially difficult to increase the production efficiency of the piston material 1 with the conventional one.

[0007]

[The purpose of the device]

 It is an object of the present invention to provide a gravity die casting apparatus that accelerates the solidification rate of the upper part of the riser without causing shrinkage cavities in the product, thereby shortening the casting cycle.

[0008]

[Means for Solving the Problems]

 The gravity die casting apparatus according to the present invention has a cylindrical heat retaining lining that is integrally fitted to a die that forms a casting space and that forms a feeder space that communicates with the casting space. It is characterized in that it is provided with a cooling means which is provided on the upper part and promotes heat dissipation of the upper part of the heat insulating lining.

[0009]

[Action]

 According to the present invention, volumetric shrinkage occurs with the solidification of the molten metal filled in the casting space formed in the mold, but the solidification rate of the molten metal in the feeder space is slower than that in the casting space due to the heat retaining lining. Is adjusted so that a part of the molten metal is drawn into the casting space from the feeder space side communicating with the casting space.

Further, the heat retaining lining in the upper part of the feeder space is cooled by the heat radiation effect of the cooling means, so that the solidification of the feeder occupying the upper part of the feeder space is promoted.

[0011]

【Example】

 FIG. 1 shows a cross-sectional structure of an embodiment in which the gravity die casting apparatus according to the present invention is applied to manufacture of a piston material 1 of an internal combustion engine shown in FIGS. That is, the gravity die casting apparatus in this embodiment is for casting two piston materials at the same time, and the side die 11 forming the outer peripheral surface of each of the two piston materials is a front die not shown. And a rear mold 13 in which a divisional surface (not shown) is tightly butted to the front mold via a pair of knock pins 12 to form a split structure. A mold opening / closing drive (not shown) that reciprocates the front mold and the rear mold 13 in the facing direction (direction perpendicular to the paper surface in the drawing) of these front mold and rear mold 13. Each mechanism is assembled. A sprue 14 for pouring molten metal (not shown) is formed in the center of the side die 11, and a pair of runners 15 connected to the sprue 14 serve as piston materials in two casting spaces 16 respectively. A blind riser space 17 is formed at the side end of the side mold 11 on the opposite side of the runner 15 with the casting space 16 interposed therebetween.

The lower mold 18 whose lower end can be engaged with the side mold 11 is provided so as to be able to move up and down via an elevating mechanism (not shown), and the side mold 11 is detachable at the rising end position thereof. It is supposed to be done. Further, the core 19 of the divided structure protruding from the surface of the lower mold 18 is slidably fitted to the lower mold 18, but the core 19 is not shown in the figure. Since it is fixed integrally with the lower mold 18, the lower mold 18 is actually moved up and down with respect to the core 19 according to the operation of the lifting mechanism of the lower mold 18 described above.

It should be noted that the front mold and the rear mold 13 described above are each provided with a taper pin 20 protrudingly fitted to the core 19, and a cylindrical space formed by these taper pins 20 is formed. It is used as a fitting hole for piston pins after machining.

The side metal mold 11 is sandwiched between the lower metal mold 18 and the side metal mold 11, the lower metal mold 18 and the core 19 to partition the above-mentioned casting space 16 and the top of the piston material. The upper mold 21 forming the surface is supported by a lifting mechanism (not shown) so as to be able to move up and down with respect to the core 19. At the center of the upper mold 21, a heat retaining line that forms a feeder space 22 is provided. The steering wheel 23 is integrally fitted. This heat insulating lining 23 having a stepped outer peripheral surface is formed of a material having a small thermal conductivity such as ceramics typified by porous silicon nitride. It is set thinner than the wall thickness of the lower end. Further, a cooling metal 24 made of a metal such as iron is fitted as a cooling means according to the present invention on the outer periphery of the upper portion of the heat insulating lining 23 whose thickness is set thinner than the lower end portion, and the upper mold 21 It is integrated with.

Therefore, when a predetermined amount of molten metal is injected from the sprue 14 in the casting state shown in FIG. 1, this molten metal flows from the runner 15 into the casting space 16 and the blind feeder space 17, and the liquid surface of the molten metal is further pushed. The upper part of the hot water space 22 is filled. Then, with the passage of time, the molten metal in the casting space 16 first solidifies, and then the molten metal solidifies in the order of the blind riser space 17 and the riser space 22, but the upper part of the riser space 22 is cooled. Since it is surrounded by 24, the solidification of the upper part of the riser of the piston material formed by this riser space 22 is promoted.

That is, since the outer peripheral surface of the riser solidifies faster than the conventional one when the piston material is demolded, even if the casting cycle is set shorter than that of the conventional one, the center boss of the predetermined shape is not It can be formed in the center of the top surface without any problems, and the production efficiency of the piston material can be improved.

When the piston material is removed from the die, first, the upper die 21 is retracted upward, and then the side die 11 is divided and the front die and the rear die 13 are separated from each other. Then, the lower mold 18 descends and the piston material is held by the core 19. Here, the core 19 is disassembled and the piston material is removed from the core 19.

In this embodiment, the cooling metal 24 is used as the cooling means, and the cooling metal 24 is fitted on the outer periphery of the upper portion of the heat insulating lining 23. However, the heat radiation of the upper portion of the heat insulating lining can be promoted. Any cooling means may be used. For example, the wall thickness of the upper portion of the heat insulating lining 23 is made much smaller than the wall thickness of the lower portion, or the above-mentioned chill 24 is formed as a cooling space, and a cooling fluid such as water is supplied to this cooling space. While connecting the discharge means, a temperature sensor for detecting the temperature of the heat retaining lining 23 is embedded above the heat retaining lining 23, and the supply of the cooling fluid to the cooling space is controlled based on the detection signal from the temperature sensor. Thus, it is also possible to adjust the solidification rate of the upper part of the feeder of the piston material formed by the feeder space 22.

[0019]

[Effect of device]

 According to the gravity die casting apparatus of the present invention, the cooling means for promoting the heat dissipation of the upper part of the heat retaining lining is provided on the upper part of the heat retaining lining, so that the heat dissipation of the upper part of the feeder where the solidification tends to be delayed is improved, As a result of being able to solidify the outer peripheral surface of the molten metal reliably, it is possible to shorten the casting cycle compared to the conventional one and improve the manufacturing efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of an embodiment in which a gravity die casting apparatus according to the present invention is applied to casting piston material of an internal combustion engine.

FIG. 2 is a side view showing an appearance of an example of a piston material for an internal combustion engine by casting.

FIG. 3 is a plan view of the piston material shown in FIG.

[Explanation of Codes] 11 Side Mold 12 Knock Pin 13 Rear Mold 14 Yukou 15 Funnel 16 Casting Space 17 Blinded Hot Metal Space 18 Lower Mold 19 Core 20 Tapered Pin 21 Upper Mold 22 Hot Water Space 23 Thermal insulation lining 24 Chilled money

Claims (1)

[Scope of utility model registration request] 1. A cylindrical heat retaining lining that is integrally fitted to a mold that forms a casting space and that forms a riser space that communicates with the casting space, and is provided above the heat retaining lining. A gravity die casting apparatus comprising: a cooling means for promoting heat dissipation from the upper portion of the heat insulation lining.