JPH0442051Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a full mold casting apparatus using a fugitive model.

(Prior art) Conventionally, a mold is formed by filling a mold flask with non-caking dry molding sand surrounding a fugitive model made of expanded polystyrene, etc., and molten metal is poured into the mold. A full mold casting apparatus is known that injects material to burn and vaporize the model while forming a cast product having a shape corresponding to the model (see Japanese Utility Model Publication No. 37613/1983). In order to improve the accuracy and strength of the products cast by this full mold casting device, it is possible to increase the feeder pressure by pressing the molten metal in the solidification process at the pouring spout using a mechanical pressurizing means using a plunger or the like. It is being done. However, since this full mold casting equipment uses non-caking dry foundry sand as a filler for mold formation, when the molten metal is pressed by the plunger, it comes into contact with the wall of the runner and solidifies. When the casting material in this state is forcibly pushed down, the frictional resistance causes a mechanical pressurization loss, and there is a problem in that the walls of the molding sand forming the runners collapse.

(Purpose of the invention) The present invention was made in order to solve the above-mentioned problems, and has a simple structure that properly pressurizes the molten metal without causing pressure loss or collapse of the runner. The present invention provides a full mold casting device that can increase pressure and form cast products with excellent precision and strength.

(Structure of the invention) The present invention forms a mold by embedding a fugitive model in a filler made of heat-resistant particles, and injects molten metal into the mold to form a shape corresponding to the fugitive model. In a full mold casting apparatus for molding a cast product, a pressure cup for a feeder forms a pressure chamber above a pouring hole formed on the upper end surface of the filler, and a A gas passage for supplying high-pressure gas to the chamber, and a sealing member attached to the feeder pressure cup and covering the upper end surface of the filler, the sealing member being formed of a flexible member. This is what I did.

According to the above configuration, high-pressure gas is introduced from the gas passage into the pressure chamber that is airtightly formed by the feeder pressure cup and the seal member, and the high-pressure gas flows into the molten metal in the runner to the feeder. Pressure will be applied.

(Embodiment) FIG. 1 shows an embodiment of a full mold casting apparatus according to the present invention. This full mold casting apparatus includes a mold flask 1, a filler 2 made of heat-resistant particles such as non-caking dry molding sand filled in the mold flask 1, and a foamed foam embedded in the filler 2. It is equipped with a fugitive model 3 made of polystyrene or the like. A molten metal pouring spout 4 is formed on the upper end surface of the filler 2, and a feeder pressure cup 5 is disposed above the spout 4. In addition, the above-mentioned pouring port 4 and the above-mentioned vanishing model 3
It is communicated with by a runner 6.

The feeder pressure cup 5 is supported by an elevating cylinder 7 so as to be able to rise and fall freely, and has a recess 8a at its lower end for forming a pressure chamber 8 above the pouring spout 4 in the lowered state shown by the imaginary line. ing. Further, the feeder pressure cup 5 is supplied with an electromagnetic switching valve 10 from a high pressure gas supply source 9 such as a compressor.
A gas passage 12 is formed for supplying compressed air or high pressure gas such as nitrogen gas, carbon dioxide gas, argon, helium, etc., supplied through the pressure conduit 11 into the pressure chamber 8 . Further, in the recess 8a forming the pressure chamber 8, a heat shield plate 13 is attached to the mounting portion 14 via bolts 15 to prevent hot air rising from the pouring port 4 from being introduced into the gas passage 12. The sealing member 16 has a through hole 16a corresponding to the pouring port 4 and covers the upper end surface of the filler 2 when the feeder pressure cup 5 is in the lowered state. It is attached to the lower end step portion 17 via a bolt 18.

In order to form a cast product using the full mold casting apparatus configured as described above, aluminum alloy and cast steel are poured into the runner 6 from the pouring spout 4 with the riser pressure cup 5 raised. A molten metal 19 made by melting a casting material such as cast iron is supplied, and the fugitive model 3 is burned from below and vaporized by the molten metal 19, and the molten metal 19 is filled into the mold. Thereafter, as shown in FIG. 2, the feeder pressure cup 5 is lowered by the lifting cylinder 7, and its lower end is brought into contact with the upper end surface of the filler 2, and the inner part of the feeder pressure cup 5 is lowered. The upper end surface of the filler 2 located at is hermetically covered with a sealing member 16.

Next, the electromagnetic switching valve 10 is brought into a conductive state, and the pressure gas supply source 9 is supplied with 0.5 to 20 kgf/
High-pressure gas pressurized to about cm ² is introduced into the pressure chamber 8 through the pressure conduit 11 and the gas passage 12, and the molten metal 19 in the runner 6 is pressurized by this high-pressure gas for a predetermined period of time. This pressurization time is normally about 30 to 300 seconds after the injection of the molten metal 19 is completed until the solidification of the molten metal 19 is completed.

In this way, high pressure gas is introduced into the pressure chamber 8 which is formed in an airtight state by the recess 8a of the feeder pressure cup 5 and the seal member 16.
The molten metal 19 located in the center, excluding the peripheral area that is in a solidified state in contact with the runner 6, is pressurized by the high-pressure gas and pushed down, effectively increasing the feeder pressure without causing pressure loss. can be done. That is, by contacting the runner 6, the peripheral edge of the cooled and solidified molten metal 19 is prevented from being pushed down by the frictional resistance acting between the runner 6 and the pressurizing force of the high-pressure gas. The feeder pressure is effectively increased because it acts concentratedly on the molten part in the center. Moreover, unlike when the molten metal 19 is pressed by mechanical pressure means such as a plunger, the peripheral edge of the solidified state is not forced down, which causes the wall surface of the runner 6 to collapse. The filling material 2 can be stably held in a predetermined state.

Furthermore, the feeder pressure cup 5 does not need to be configured to cover the entire upper surface of the mold flask 1, but may be configured to surround the periphery of the pouring spout 4 over a predetermined range. Miniaturization and simplification are possible. Also, the upper end surface of the filler 2 is connected to the pouring port 4.
Since it is covered with the sealing member 16 except for the part corresponding to the filling material 2, it is possible to prevent pressurization loss caused by high pressure gas from entering the filling material 2, and also to prevent the filling material 2 from scattering. be able to. In addition, since the sealing member 16 is formed of a flexible material such as a synthetic resin material or metal foil, the sealing member 16 can be closely attached along the unevenness of the upper end surface of the filler 2. There is an advantage that the pressure chamber 8 can be completely airtight to more effectively reduce pressurization loss, and the scattering of the filler 2 can be more effectively prevented.

Further, in the above embodiment, the seal member 16 is provided with the through hole 16a corresponding to the pouring port 4, and is configured to prevent the seal member 16 from coming into contact with the molten metal 19 and being burnt out. As shown in Fig. 3, a ring member 20 for attaching a sealing member is removably attached to the lower end of the feeder pressure cup 5', so that it can be used repeatedly. The seal member 21 may be configured to be replaced. In this case, by using a flexible material that has a melting point lower than that of the molten metal 19 as the sealing member 21, there is no need to provide a through hole corresponding to the pouring spout 4. The work of positioning them facing each other becomes unnecessary. That is, as shown in FIG. 4, when the feeder pressure cup 5' is lowered to supply high-pressure gas into the pressure chamber 8 after the molten metal 19 is injected, the sealing member 21 is caused to close to the filler 2 by this high-pressure gas. It is pressed into close contact with the upper end surface of the
By contacting the molten metal 19 in the pouring port 4 and melting this part with the heat of the molten metal 19, a through hole for supplying high pressure gas to the molten metal 19 is formed, so the through hole is provided in advance. There is no need.

(Effects of the invention) As explained above, the present invention constructs a pressure chamber by arranging a pressure cup for a riser on the upper end surface of a filler made of heat-resistant particles in which a fugitive model is embedded, and With the upper end of the filler covered airtightly by the member, high pressure gas is supplied into the pressure chamber to pressurize the molten metal in the solidification process at the pouring spout, pushing down only the molten metal in the center. This makes it possible to effectively increase the feeder pressure while preventing the runner from collapsing. Therefore, it is possible to improve the accuracy and strength of a cast product with increased feeder pressure without causing pressure loss with a simple configuration.

Furthermore, by covering the upper end surface of the filler with the sealing member, it is possible to prevent the filler from scattering, and to further improve airtightness by preventing high-pressure gas from entering the filler. There is an effect that it can be done.

[Brief explanation of the drawing]

1 and 2 are sectional views showing an embodiment of a full mold casting apparatus according to the present invention, and FIGS. 3 and 4 are sectional views showing main parts of another embodiment of the present invention. 2...Filling material, 3...Disappearance model, 4...Pouring port, 5, 5'...Pressure cup for riser, 8...Pressure chamber, 12...Gas passage, 16, 21...Sealing member .

Claims (1)

[Scope of utility model registration request] Full mold casting, in which a mold is formed by embedding a fugitive model in a filler made of heat-resistant particles, and molten metal is poured into the mold to form a cast product with a shape corresponding to the fugitive model. The apparatus includes a feeder pressure cup forming a pressure chamber above the pouring port formed on the upper end surface of the filler, and a gas passage that passes through the feeder pressure cup and supplies high pressure gas to the pressure chamber. and a sealing member that covers the upper end surface of the filler attached to the feeder pressure cup, and the sealing member is made of a flexible member. Device.