JPS5884662A - Pressure casting method and equipment - Google Patents

Abstract

PURPOSE:To obtain castings having good casting surfaces and having no blowholes by pouring molten metal into molds through pouring port, closing the pouring port with a cover member, increasing the air pressure in a hermetic chamber contg. the molds above the atmospheric pressure and pressurizing the molten metal in casting cavity through the casting sand parts of the molds. CONSTITUTION:Molten metal is poured through sprues 10 into casting cavity 9. After the pouring, a cylinder device 3 is actuated to move a cover member 12 downward to bring the circumferential edge part 4 of its opening into abutment on a base plate 1, thereby closing a hermetic chamber 5. Thereafter, a valve 17 for supplying compressed air is opened to supply compressed air into the chamber 5 to increase the pressure therein above the atmospheric pressure. The pressure in the chamber 5 pressurizes the molten metal in the cavity 9 through the space among the said particles of a drag 6 and a cope 7. Thus the flash penetration of the molten metal and the oozing of the molten metal from the surface of the solidified metal by the pressure difference between the pressure of the molten metal in the cavity 9 and the internal pressure of the dies are averted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure casting method and a casting apparatus used for carrying out the casting method, and in particular to a pressure casting method using a mold in which at least a part of the wall surface constituting a casting cavity is made of anti-sand. Pertains to casting methods and equipment for pressure casting.

In casting methods that use a mold in which at least a portion of the wall defining the casting cavity is made of sandproof material, such as a mold casting method using a sand core or a sand mold casting method, the casting cavity is Compared to the casting method, which uses a mold in which all of the walls to be defined are made of metal, the solidification time of the metal is longer, more gas is generated, and it is difficult to avoid gas defects such as pinholes. It is difficult to cast reliable, high-quality pressure-resistant products.

In view of the above-mentioned problems with casting methods using sand cores or sand molds, the mold is placed in an airtight chamber, and the pressure in the airtight chamber is raised to above atmospheric pressure to pressurize the bath temperature in the casting cavity together with the mold. A pressure casting method has been proposed in which the bath temperature is solidified in a pressurized atmosphere, and this casting method shortens the solidification time of the metal and eliminates gas defects even if a sand core or sand mold is used. It has the advantage that it can suppress the occurrence of sand, and that even if sand cores and sand molds with low strength are used, they will not be damaged.

However, in the past, this pressure casting method created a pressurized atmosphere by increasing the air pressure in the airtight chamber after the pouring was completed. The rise in internal pressure is delayed, and this creates a differential pressure between the bath temperature in the casting cavity and the sand core and the inside of the sand mold, causing the molten metal to be inserted and the bath temperature to seep out from the solidified surface, resulting in a high-quality casting surface. It is difficult to obtain castings with For this reason, conventionally, rough casting surfaces have been prevented by using sand cores, sand molds, or painted molds with low air permeability, but even when these molds are used, it is difficult to obtain castings with very good casting surfaces. I can't do it,
Furthermore, the effect of uniformly pressurizing the entire molten metal within the casting cavity is reduced, and there is a risk that the original effects of the pressure casting method may not be fully exhibited.

In view of the above-mentioned problems in the conventional pressure casting method, the present invention proposes an improved pressure casting method that can cast high-quality castings with good casting surfaces without impairing the original effects of the pressure casting method. The object of the present invention is to provide a casting device used to implement the m-ary system and its casting method.

This purpose is to perform pressure casting using a mold in which at least a portion of the wall defining the casting cavity is made of anti-sand material.
After pouring the molten metal, the pouring port is closed with a lid member, and then the pressure in the airtight chamber housing the mold is raised to above atmospheric pressure, and the bath temperature in the casting cavity is pressurized through the casting sand part of the mold. A pressurized casting method characterized by a pressure casting method and an apparatus for carrying out the casting method include an openable and closable airtight container that accommodates a mold, a lid member that closes a pouring port of the mold, and a compressed gas supply to the airtight container. This is achieved by a pressurized casting apparatus characterized in that it has a compressed gas supply device.

Further, according to a detailed feature of the present invention, the lid member may be configured to have an air permeability equal to or lower than the air permeability in sand prevention of the mold.

A lid member having air permeability is useful in mold casting using a sand core.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of a pressure casting apparatus according to the present invention. In the figure, 1 indicates a substrate, and 2 indicates a box member with an opening on the side of the substrate 1. The box member 2 is driven vertically in the figure by a cylinder device 3, and when it is in the lowered position as shown in the figure, its opening peripheral edge 4 abuts against the substrate 1, and an airtight chamber 5 is formed inside the box member 2 together with the substrate 1. It is designed to be configured.

A lower mold 6 and an upper mold 7 are arranged on the substrate 1, and these are housed in an airtight chamber 5.

The lower mold 6 and the upper mold 7 are constituted by sand molds, and define the casting cavity 9 in cooperation with a sand core 85-. The upper mold 7 is provided with a plurality of sprues 10, each of which opens on the upper surface of the upper mold 7.

A lid member 12 is attached to the ceiling surface of the box member 2 by a holder 11.
is provided to be movable in the vertical direction, and the lid member faces the upper surface of the upper mold 7 and is flexibly attached downward in the figure, that is, toward the upper surface of the upper mold 7, by a compression coil spring 13. Forced.

The lid member 2 is also provided with a compressed gas inlet/outlet 14, which is connected to a compressed gas supply valve @19 such as a compressor via a flexible hose 15, a conduit 16, a compressed gas supply valve 17, and a conduit 18. Also connected to the hose 15, conduit 16.
It is connected to an exhaust valve 21 via 20. Also, the conduit 16
A pressure gauge 22 is provided. The compressed gas used in this casting method may be air when casting ferrous metals, but preferably is a knee gas in order to obtain the effect of reducing inclusions when casting active metals such as aluminum.

Next, a description will be given of how to carry out the pressure casting method according to the present invention using the pressure casting apparatus having the above-mentioned configuration.

First, the lower mold 6 is placed on the substrate 1 with the lid member 12 raised.
The sand core 8 is attached to the lower die, and the upper die 7 is attached to the lower die 6, and the molds are clamped.

Next, molten metal is injected into the casting cavity 9 from the sprue 10.

After pouring is completed, the cylinder device 3 is operated to close the lid member 12.
is lowered and its opening peripheral edge 4 is brought into contact with the substrate 1,
Close the airtight chamber 5. At this time, the lid member 12 is pressed against the upper surface of the upper mold 7 by the spring force of the compression coil spring 13,
The sprue 10 is closed. Next, the compressed gas supply valve 17 is opened, compressed air is supplied from the compressed air supply device 19 into the airtight chamber 5, and the pressure inside the airtight chamber is raised to a predetermined pressure above atmospheric pressure, for example, about 5 to 10 atmospheres. The pressure in the airtight chamber 5 is applied to the molten metal in the casting cavity 9 through the sand particles of the lower mold 6 and the upper mold 7, which are constructed of anti-sand materials, and the molten metal is pressurized. Therefore, in this case, the pressure inside the lower mold and the upper mold rises before the molten metal in the casting cavity 9, so that a state where the pressure inside the mold is lower than the molten metal pressure in the casting cavity 9 does not occur. The pressure difference between the molten metal pressure in the casting cavity and the internal pressure of the mold prevents molten metal from being inserted or seeping out from the solidified surface.

The pressurized atmosphere in the airtight chamber 9 is maintained until the molten metal in the casting cavity 9 is completely solidified, and after the molten metal is completely solidified, the compressed gas supply valve 17 is closed and the exhaust valve 21 is opened. Evacuate to reduce the pressure in the airtight chamber. After this, the cylinder device 3 is driven to raise the lid member 12, and then the mold is opened and the cast product is taken out.

FIG. 2 shows another embodiment of the pressure casting apparatus according to the present invention. In FIG. 1, parts corresponding to those in FIG. 2 are designated by the same reference numerals as in FIG. In this embodiment, the lower mold 6 and the upper mold 7 are made of metal molds, and only the core 8'' is made of anti-sand material. The sand core 8 is configured as a hollow body, and communicates with the airtight chamber 5 at its baseboard portion 8a. Further, the lid member 12 is made of a refractory material having an air permeability equal to or lower than that of the sand core 8.

In this embodiment as well, the sprue 10 is closed by the cover member 12 before the pressure in the airtight chamber 5 is increased after pouring, and then the pressure is increased by increasing the pressure in the airtight chamber 5. The molten metal in the casting cavity 9 passes through the sand core 8 and the lid member 12, and the molten metal does not enter the sand core or seep out from the solidification surface without causing a state in which the internal pressure of the sand core is lower than the molten metal pressure. It is possible to obtain a high-quality casting that has no gas defects, has a good casting surface, and is free from gas defects.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are longitudinal sectional views each showing an embodiment of a pressure casting apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Lid member, 3... Cylinder device, 4... Opening peripheral part, 5... Airtight chamber, 6... Lower mold, 7... Upper mold. 8... Sand core, 9... Casting cavity, 10...
Spruce. DESCRIPTION OF SYMBOLS 11... Holder, 12... Lid member, 13... Compression coil 9-spring, 14... Compressed fluid inlet/outlet, 15... Flexible hose, 16... Conduit, 17... Compressed gas supply valve, 1
8... Conduit, 19... Compressed gas supply device, 20...
・Conduit, 21...Exhaust valve, 22...Pressure gauge Patent applicant: Toyota Motor Corporation representative
Attorney Patent Attorney Akashi
Takeshi Masa 10-

Claims (4)

[Claims] (1) In a casting method in which pressure casting is performed using a mold in which at least a portion of the wall surface defining the casting cavity is made of anti-sand material, the metal is poured from the pouring port of the mold, and after pouring, the Pressure casting characterized in that the sprue is closed by a lid member, and then the pressure in the airtight chamber housing the mold is raised to above atmospheric pressure, and the molten metal in the casting cavity is pressurized through the casting sand part of the mold. Law. (2) Pressure casting according to claim 1, wherein the lid member has an air permeability that is equal to or lower than the air permeability of the sand portion of the mold. Law. (3) Pressurization characterized by having an openable and closable airtight container that accommodates a mold, a lid member that closes a pouring port of the mold, and a compressed gas supply device that supplies compressed gas to the airtight container. Casting equipment. (4) Pressure casting according to claim 3, wherein the lid member is configured to have an air permeability equal to or lower than the air permeability in sand prevention of the mold. Device.