JPS63256253A - Die casting method - Google Patents

Abstract

PURPOSE:To obtain an as-cast product without any defect in thick part, by arranging a dummy member, which is made of the material having melting point lower than that of a raw material for casting, near the the thick part in a die and removing resolidified dummy member after executing die casting. CONSTITUTION:By pressurizing a plunger during operating a die casting apparatus 10, molten aluminum having high temp. is pressed in a cavity 26 through a plunger sleeve 38. The molten aluminum is brought into contact with inserts 48, 50 in the thick part forming bolt hole and filler hole in the cavity 26. The melting point of the inserts 48, 50 is low, because of zinc alloy, and as it resolidifies after all of the molten aluminum has solidified, the defects of shrinkage hole, etc., are concentrately developed at the positions, where the inserts 48, 50 are inserted. After the parts of the inserts 48, 50 solidifies, an ejecting device 28 is worked and the as-cast product is ejected to out of the die by ejecting pins 34, 36. The insert part is removed by cutting and the product without any defect in the bolt hole, etc., is obtd.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a mold casting method such as a die casting method.

This mold casting method is used, for example, to cast a thin-walled material into which a thick-walled part is to be formed into a pilot hole.

[Conventional technology]

Generally speaking, mold casting has a fast solidification rate, so
It is difficult to control the solidification rate and it is difficult to obtain directional solidification. This tendency is particularly strong in the case of die-casting, which involves casting thin-walled materials with thick-walled parts.Normally, in order to avoid defects such as shrinkage cavities, the material is made to reduce the thick-walled parts as much as possible. The design will be carried out.

[Problem that the invention seeks to solve]

For thick parts with holes in the product, insert pins are placed in the mold in advance at the casting stage, and pilot holes are formed. Since there is a limit to this, there have been problems in that the nesting pins can overheat, resulting in cracks, seizures, etc., and leakage defects in the cast material.

Accordingly, an object of the present invention is to reduce defects such as cavities in the thick-walled portion in die casting of a thin-walled material having the thick-walled portion to be removed in a subsequent process.

[Means for solving problems]

Therefore, the mold casting method of the present invention takes advantage of the fact that the resolidification of the dummy member lags behind the solidification of the material part of the product, and collects defects such as shrinkage cavities in the resolidified dummy member, so that the material part It is characterized by eliminating the defects of

Specifically, the configuration of the present invention is as follows.

The present invention is a method for performing mold casting of a thin-walled material having a thick-walled portion.

First, a dummy member made of a material with a melting point lower than that of the casting material forming the raw material is placed in a mold near the thick portion.

After the mold casting is performed, the resolidified dummy member is removed.

[Effect]

According to the above-described mold casting method of the present invention, when the molten metal enters the mold and contacts the dummy member, the dummy member receives the heat of the molten metal and melts because the dummy member has a low melting point. During the solidification process, since the dummy member solidifies slowly, defects such as shrinkage cavities gather on the dummy member. The dummy member is removed by cutting or the like along with defects such as cavities in a subsequent process.

〔Example〕

Next, an embodiment of the mold casting method according to the present invention will be described based on FIGS. 1 and 2.

This example is an example of application to casting of a transmission case cover.

FIG. 1 is a cross-sectional view of a die-casting apparatus used in the method of this embodiment, and FIG. 2 is a partially enlarged view of the section shown by the arrow ``■'' in FIG. 1.

The die-casting apparatus 10 shown in FIG. 1 includes a fixed main die 14 attached to a fixed die plate 12, and a movable main die 20 attached to a movable die plate 16 via a die base 18.

A fixed insert 22 is disposed on the fixed main mold 14, and a fixed insert 22 is disposed on the fixed main mold 14.
0 is provided with a movable insert 24, and these mold inserts 22
A cavity 26 is defined by cavity surfaces 22a and 24a of 24 and 24. Movable die plate 1
A product material discharge device 28 is disposed on the 6 side.

The ejection device 28 has extrusion pins 34 and 36 supported by extrusion plates 30 and 32 that are connected to the movable main mold 20 and the movable insert 2.
4 through the insertion holes 20bSc and 24b, c. The tips of the extrusion pins 34 and 36 are flush with the cavity surface 24a during pouring, but after the pouring and solidification, the extrusion plates 30 and 32 move toward the cavity 26 to eject the product material. It is made to be. Note that the fixed die plate 12 is provided with a plunger sleeve 38, and the fixed main die 14 and the fixed insert 22 corresponding thereto are provided with a sprue bush 40. And the movable insert 2 corresponding to the sprue bush 40
4, a sprue core 42 is disposed.

Inserts 4 are inserted into the fitting holes 44 and 46 of the stationary insert 22 and the movable insert 24 in the portion of the cavity 26 that forms the thick wall portion of the cast raw material (an enlarged view is shown in FIG. 2).
8 and 50 are fitted. The inserts 48 and 50 are made of a zinc alloy (4 wt% AJ-3 wt% Cu-balance Zn), and are provided with bolt holes and oil filler holes, respectively, by operations described below. These bolt holes and filler holes were conventionally cast with nesting pins installed, and this is where overheating of the nesting pins caused defects such as cavities and leakage. .

Next, a die-casting method using the above-described die-casting apparatus 10 will be explained.

When the die-casting device 10 is operated and molten aluminum at a temperature of about 640° C. is pressurized into the cavity 26 through the plunger sleeve 38 by pressurizing the tip during the plunge (not shown), the poured aluminum alloy flows into the cavity 26. In thick-walled parts that form bolt holes and filler holes,
Contact with inserts 48 and 50. insert 48
Since the melting point of molten aluminum and 50 is 380° C., which is lower than that of molten aluminum, the molten aluminum is cooled by the fixed insert 22 and the movable insert 24 and melts during the solidification process. insert 48
and 50 increases its volume when melting, so
It acts as a feeder to the surrounding molten aluminum.

Furthermore, when the molten aluminum solidifies and the temperature drops below 380°C, the molten inserts 48 and 50 re-solidify, but at that point all of the molten aluminum has solidified, so defects such as shrinkage cavities will not occur. This will occur concentratedly at the locations where the inserts 48 and 50 were present.

After the inserts 48 and 50 have solidified, the ejection device 28 is actuated to eject the cast transmission blank from the mold by the ejector pins 34 and 36. And the insert 48 in the transmission rough profile
and 50 were removed by cutting to form bolt holes and filler holes.

FIG. 3 shows a photograph (1x magnification) of the metallographic structure in the cross section of the thick part of the die-cast rough profile material in this example.

It can be seen that shrinkage appears concentrated at the tip of the dummy member, and the surrounding AI casting is in a healthy state. In addition,
As a dummy member, Zn-4wt%A1-3%Cu
Alloy was used.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. .

In the above-mentioned embodiment, an example of die casting was given as the mold casting, but other than this, it can also be applied to normal mold casting,
It is possible.

In addition, although we have described a case in which a hole is formed as a thick wall part of a thin material on which a dummy member is arranged, the dummy member can be arranged not only in the hole but also adjacent to the thick part in the subsequent process. The dummy member may be removed.

〔Effect of the invention〕

As described above, according to the mold casting method of the present invention, defects collected in the dummy member, such as cavities, are removed in the subsequent process, so that there are no defects in the thick portion of the product material.

In addition, since it is only necessary to place the dummy member inside the mold,
This method has the advantage of not complicating the equipment and can be achieved by making slight improvements to existing equipment.

[Brief explanation of drawings]

1 to 3 are drawings and photographs for explaining an embodiment of the mold casting method according to the present invention. FIG. 1 is a sectional view of a die-casting apparatus used in the method of this embodiment. FIG. 2 is a partially enlarged view of the section shown by the arrow ``■'' in FIG. 1. Figure 3 is a metal structure photograph (
(1x magnification). 10--Die casting casting device 12--Fixed gouge plate 14--Fixed main mold 16--Movable gouge plate 1111--Die base 20-- - Movable main mold 22.24...Insert 26--Cavity 48.50--Insert (dummy member) Applicant Toyota Motor Corporation Fig. 1 24? i (Me 1)

Claims (1)

[Claims] When performing mold casting of a thin-walled material having a thick-walled portion, a dummy member made of a material having a lower melting point than the casting material forming the material is placed in the mold near the thick-walled portion. A mold casting method characterized by removing the resolidified dummy member after mold casting.