JPH0317582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a casting method using a fugitive model made of expanded polystyrene.

Conventional technology There are various types of casting methods of this type.
The method previously filed and disclosed by the applicant of the present invention (Japanese Patent Application No. 61-56272) is carried out approximately as shown in FIG.

In the figure, a is a flask, b is a nonflammable filler such as sand, c is a fugitive model made of expanded polystyrene, d is a runner made of expanded polystyrene, and e is a sprue. Further, f indicates a protective layer such as a coating mold, g indicates a furnace, and h indicates a molten metal. Further, i is a gas vent, which has a small hole j, and an ignition device k is provided above it.

Molten metal (hereinafter referred to as hot water) h is supplied from the sprue e, passes through the runner d after being vaporized, reaches the fugitive model c, vaporizes it, and enters the space created there to perform casting. be exposed.

The runner d and the model c are vaporized, and the gas passes through the fine gaps in the filling material b, and enters the gas vent i through its small hole j.
The gas enters from the bleed gas i, rises through the bleed gas i, and is ignited by the ignition device k at the upper end of the bleed gas i.

In addition, as another method, although not shown in the drawings, instead of using the gas evacuation gas i, a small hole is formed in the side wall l of the flask a, and the gas is discharged to the outside through this small hole, or an outer wall is formed on the outside of the side wall. In some cases, a pump is connected to the small chambers formed in the outer wall and the side wall, and the gas is systematically evacuated by the pump.

Problems to be Solved by the Invention However, each of the above disclosed or conventional methods includes the following problems. The problem is that the speed of hot water reaching model c from runner d is sometimes insufficient. If the speed of the hot water passing through the runner d is slow, the vaporization of the model c will not occur rapidly, but if it is carried out slowly, residues from the thermal decomposition of polystyrene foam will be generated on the inner surface of the protective layer f such as the coating mold. It may stick. This residue faithfully forms the surface of the casting, resulting in defective products.

In addition, the flow of hot water in the runner d is slow, and therefore the flow of the generated gas may be obstructed by the hot water, and in such a case, an explosion due to the gas may occur. This explosion causes the collapse of the filling material b, and therefore a sound cast product may not be obtained. Furthermore, depending on the cast product, there may be cases where it is desired to increase the flow rate of hot water only in a certain part of the runner. This is to ensure that hot water is poured into unstable areas.

This invention was made to solve these problems, and its purpose is to increase the speed of hot water passing through the runners, thereby preventing the heat of foamed polystyrene from forming on the inner surface of the coating mold. It is possible to prevent the occurrence of defective products due to the adhesion of decomposition residue,
Another object of the present invention is to provide a casting method using a fugitive model, which can prevent the above-mentioned explosion of the runner and increase the speed of passage through a desired portion of the runner.

Means for Solving the Problems This invention is described by providing a fugitive model made of foamed polystyrene with a pillar-shaped runner made of foamed polystyrene connected to a sprue and forming an increased surface area, and connecting the model and the hot water A fugitive model made of foamed polystyrene is used, which is characterized by forming a coating layer on the outside of the road, burying this in a nonflammable filling filled in a flask, and injecting molten metal from the sprue. This is a casting method for castings.

Function When hot water is injected from the sprue, the hot water passes through the runner. In this case, first contact the surface of the runner and vaporize it. Therefore, since the surface area increasing portion has an increased surface area, it can be vaporized relatively faster than other portions.

Further, the vaporization of the other portions is assisted and promoted by the vaporization that is performed in succession to the vaporization of the above-mentioned increased portion, although the other portions are vaporized separately. Further, the surface of the vaporized gas that comes into contact with the hot water increases by the amount of the increased portion provided, and therefore, the number of plates for removing the hot water is reduced accordingly, making it easier for the gas to escape. Furthermore, since the gas easily escapes, contact between the hot water and the runner becomes easier, and vaporization is more likely to occur. These causal relationships overlap to promote vaporization and escape of gas from the runner, thereby promoting hot water passage through the runner. The extent of this promotion is
For example, when the surface area increasing portion is added to make the total surface area approximately twice that of the runner alone, the total surface area is approximately twice that of a conventional runner without the surface area increasing portion. In other words, if it conventionally takes 20 seconds to pass through a runner, it takes about 10 seconds to pass through a runner with an increased surface area.

Example In Fig. 1, numeral 1 indicates a flask, which is a container made of iron plate, and a nonflammable filler such as sand is filled in the flask.
is accommodated. 3 is a sprue; 4 is a cylindrical or prismatic runner made of expanded polystyrene;
It has a surface area increasing portion 5 as shown in FIG. The portion 5 may be a slit, notch, crevice, etc. as shown in FIGS. 2 and 3, or a fin-like protrusion as shown in FIGS. 1, 4, and 5. These may be formed over the entire runner 4, or may be formed only in arbitrary parts, as shown in FIG. Good too. Next, 6 shows a fugitive model made of expanded polystyrene. The same model 6, runner 4, and increased surface area of protrusions 5
etc. have a protective layer formed on their outer surface by coating or the like, but illustration is omitted.

Next, 7 is a gas vent, which has a large number of small holes 8,
It is placed above the bottom of the flask.

9 is a furnace, and 10 is hot water. Further, 11 indicates an ignition device, and 12 indicates a flame. Although the flasks 1 are omitted, they are placed on a conveying device using rollers, and the conveying device is formed in an endless shape, and a large number of flasks 1 are intermittently moved in an endless manner by a hydraulic device (not shown). During the movement, the evanescent model with sprues and runners is set, filled with filler, shaken, and
Pouring of molten metal, ignition above the vented gas, cooling of the product, removal of the product, discharge of the filling material, etc. are performed in sequence. Note that the venting of gas due to the ignition is one example, and for venting the gas, a small hole is formed in the side wall of the flask 1, not shown, instead of using the venting body 7 as in the prior art. There is no problem even if a side wall is provided outside the side wall with small holes, a space formed between this outer wall and the side wall is formed into a chamber shape, and a pump is connected to this chamber-shaped space. It is also possible to forcibly handle and eliminate them.

Effects of the Invention This invention is constructed as described above, and by forming the surface area increasing portion in the expanded polystyrene runner, the time for hot water to pass through the runner can be accelerated, thereby preventing explosions occurring in the runner. be able to. It is also possible to prevent the production of defective products due to a delay in the time the hot water passes through the runner. Moreover, it is possible to ensure that hot water enters a desired part of the fugitive model.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a diagram showing an outline of a casting method using a fugitive model, and FIGS. Perspective view of road section, No. 7
The figure is a diagram schematically showing a homogeneous casting method previously disclosed by the applicant of the present invention. 1... flask, 2... filling, 3... sprue,
4... runner, 5... surface area increasing part, 6... vanishing model, 10... hot water.

Claims (1)

[Claims] 1 A columnar foamed polystyrene runner connected to a sprue and formed with an increased surface area is provided on a fugitive foamed polystyrene model, a coating layer is formed on the outside of the model and the runner, and this is applied to a flask. 1. A method for casting a casting using a fugitive model made of expanded polystyrene, characterized in that the model is embedded in a nonflammable filler and molten metal is injected from the sprue.