JP2006192442A - Casting mold for full mold casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a casting mold for a full mold casting process, which can suppress the faults caused on the surfaces of cast products with a simple structure. <P>SOLUTION: In the casting mold 10 to be used for casting the product in the full mold casting process in which a disappearance pattern 13 is vaporized so as to disappear by pouring the molten metal into the casting mold 10 formed by burying the disappearance pattern 13 in casting sand 12, the disappearance pattern 13 composed of acrylic resin, such as polymethyl methacrylate, is arranged such that its longer side is arranged to be almost upright, and gas discharging pipes 16 are provided to allow the upper portion of the disappearance pattern 13 to communicate with the outside of the casting mold 10, and gas discharging holes 17 are formed in the casting sand 12 to allow the disappearance pattern 13 to communicate with the outside of the casting mold 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for full mold casting.

  The full mold casting method is generally a void formed by pouring molten metal into the mold with the disappearance model made of resin foam or the like embedded in the mold, and the disappearance model vaporizing and disappearing due to the high heat of the melt. This is a casting method in which molten metal is filled in and a cast product is formed. The full mold casting method is generally used for casting a mold.

The disappearance model is a foam made of a disappearing material such as expanded polystyrene (EPS) resin, polymethyl methacrylate (PMMA) resin, polyethylene (PE) resin, or the like.
The EPS resin generally used as the material of the disappearance model contains a benzene ring in its molecular structure, and if an disappearance model made of EPS resin is adopted, this becomes a burnt residue during casting and remains on the surface of the cast product. .
As for the surface defect of this cast product, the depth from the surface exceeds the thickness of the machining allowance cut by machining, and the surface defect at the time of casting may appear as a residue in the product. In order to solve this problem, a portion where a surface defect has occurred is piled up by welding, and is subjected to surface treatment by machining again.

On the other hand, since the PMMA resin has oxygen in the molecular structure, if the disappearance model made of PMMA resin is adopted, it has excellent flammability and little burnt, but a large amount of gas is generated when the disappearance model disappears.
The gas generated by the vaporization of the disappearing model is caught in the molten metal or remains in the mold, causing defects such as a casting nest, rough surface, and molten metal in the casting.

Thus, conventionally, a structure for venting gas has been proposed in a mold for use in a full mold casting method.
For example, in the technique described in Patent Document 1, by providing a vent hole that communicates with the exhaust port of the mold in the disappearance model, the generated gas can be quickly dispersed inside the mold and guided to the exhaust port to be discharged from the mold. I am doing so.
Further, for example, in the technique described in Patent Document 2, the gas generated from the disappearance model is discharged to the outside of the mold while suppressing the discharge amount, thereby controlling the turbulence of the molten metal in the mold and discharging the gas. Prevents entrainment of bubbles in the molten metal.
JP-A-5-261470 JP 2002-219552 A

  In view of the above prior art, the present invention proposes a mold for full mold casting, which can exhibit the effect of suppressing surface defects of a cast product with a simple structure. In addition, the present invention proposes a mold structure that can improve the quality of a cast product by using an existing conventional mold.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, the molten metal is poured into a mold in which the disappearance model is embedded in the casting sand, and the product is cast while the molten model is vaporized and disappeared by the molten metal. In the mold, the vanishing mold is arranged so that its longitudinal direction is substantially vertical, an exhaust pipe is provided to communicate the upper part of the vanishing model and the outside of the mold, and an exhaust hole is formed to communicate the vanishing model and the outside of the mold. It is characterized by being formed in sand.

  According to a second aspect of the present invention, the disappearance model is made of an acrylic resin.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, exhaust gas other than the exhaust pipe can be promoted with a simple structure, and the surface defects of the cast product due to the mixing or remaining of bubbles can be suppressed. In addition, since the mold used in conventional full mold casting can be used as it is, the quality of the cast product can be improved without costing the equipment.

  According to the second aspect of the present invention, it is possible to suppress the surface defects of the cast product caused by the residue of the burning soot by configuring the disappearing mold with the material having relatively little burning soot.

Next, embodiments of the invention will be described.
FIG. 1 is a cross-sectional view showing an overall configuration of a full mold casting mold according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing another embodiment of the full mold casting mold.

First, a full mold casting mold 10 according to an embodiment of the present invention will be described.
The mold 10 includes a casting frame 11, casting sand 12 inside the casting frame 11, a vanishing model 13 embedded in the casting sand 12, a runner 15, an exhaust pipe 16, an exhaust hole 17, and the like.

  In order to efficiently exhaust the generated gas, the disappearance model 13 is installed so that its longitudinal direction is substantially vertical. That is, the cast product forming part of the mold 10 is vertically long. As a result, a larger pressure difference is generated between the upper and lower portions of the molded part of the cast product, and the gas derived from the inside of the mold 10 is gathered upward to form an environment in which the gas is more easily discharged.

The vanishing model 13 communicates with the gate 14 through the runway 15.
In addition, an exhaust pipe 16 that communicates the disappearance model 13 and the outside of the mold 10 is provided.
The exhaust pipe 16 is an exhaust path that connects the upper part of the disappearance model 13 and the outside of the mold 10, and discharges the gas in the mold 10 to the outside of the mold 10. Gas generated by the vaporization of the disappearance model 13, burners, and the like are discharged out of the mold 10 through an exhaust passage formed by the exhaust pipe 16.
The exhaust pipe 16 is composed of a cylindrical body made of ceramic or metal, and functions as a discharge path for the soot, so that it has a diameter through which the soot can pass.

Further, an exhaust hole 17 is provided for communicating the disappearance model 13 and the outside of the mold 10. The exhaust hole 17 is formed by directly drilling a small-diameter hole having a diameter of about 2 to 3 cm in the casting sand 12.
The exhaust hole 17 is an exhaust path that connects the disappearance model 13 and the outside of the mold 10, and gas generated by vaporization of the disappearance model 13 is discharged out of the mold 10 through the exhaust path formed in the exhaust hole 17. The The exhaust hole 17 is provided to promote exhaust other than the exhaust pipe 16, and before the gas generated from the disappearance model 13 rises to the upper part of the disappearance model 13, the exhaust hole 17 It will be discharged from the model 10.
In this embodiment, the exhaust hole 17 is provided below the exhaust pipe 16, but it can also be provided above. Furthermore, it is preferable to appropriately change the number and position of the exhaust holes 17 according to the scale and shape of the disappearance model 13.

  Since the exhaust holes 17 are formed in the casting sand 12, there is an advantage that the number of constituent members of the mold 10 is not increased and the configuration is simple. However, instead of the exhaust hole 17 or in addition to the exhaust hole 17, as shown in FIG. 2, an exhaust passage in which a cylindrical body 17 a is embedded in the casting sand 12 and the outside of the mold 10 communicates with the disappearance model 13. Can also be formed.

  The exhaust pipe 16 and the exhaust hole 17 can be connected not to the outside of the mold 10 but to a decompression device (not shown) to forcibly exhaust the gas inside the mold 10.

The disappearance model 13 is made of an acrylic resin foam such as polymethylmethacrylate (PMMA), and is formed in substantially the same shape as the cast product. By adopting acrylic resin such as PMMA resin as the material of the disappearance model 13, it is possible to prevent burning residue from remaining in the cast product. This is because the acrylic resin contains oxygen atoms in its molecular structure and is excellent in combustibility.
Thus, as the material of the disappearance model 13, it is preferable to use a resin excellent in combustibility such as an acrylic resin, but the material is not limited to this, and disappearance such as polystyrene (PS) resin, polyethylene (PE) resin, etc. Sexual substances can be employed.
Further, when the disappearance model 13 is made of an acrylic resin having excellent combustibility, a large amount of combustion gas is generated. The generated combustion gas is efficiently passed through the exhaust pipe 16 and the exhaust hole 17 described above. It is possible to discharge to the outside.
In addition, when the vanishing model 13 is comprised with the said acrylic resin, it is desirable to make it from the acrylic resin of higher foaming magnification, since generation | occurrence | production of combustion gas can be suppressed.

The casting process using the mold 10 having the above-described configuration is as follows.
First, a coating agent having excellent fire resistance is applied to the surface of the disappearance model 13 and dried. Note that no coating agent is applied to the exhaust pipe 16 so as not to hinder the flow of gas.
Subsequently, after the runner 15 is formed in the casting frame 11, the disappearance model 13 is fixed, and the disappearance model 13 is embedded with the casting sand 12. Then, the exhaust pipe 16 is embedded in the casting sand 12 and the exhaust hole 17 is formed, and the gate 14 is installed in the runway 15.

The molten metal is poured from the gate 14 into the mold 10 ready for casting as described above. The molten metal reaches the disappearance model 13 through the runner 15, melts the disappearance model 13, and accumulates in the mold 10. At this time, the gas of the disappearance model 13 melted and burned by the molten metal is discharged from the exhaust pipe 16 and the exhaust hole 17.
After all the disappearance model 13 is vaporized and the molten metal is filled in the mold 10 and the molten metal is cooled and solidified to form a cast product, the cast product is taken out from the mold 10.

As described above, the disappearance model 13 is made of a material with a relatively small amount of burning soot, and the gas generated from the disappearance model 13 is effectively discharged out of the mold 10 to suppress the occurrence of surface defects in the cast product. Is done.
By suppressing the surface defects, it is not necessary to build up the surface defect portions and machining after the build-up, which has been conventionally performed. Therefore, it is possible to reduce the time and cost related to the production of the cast product.
In addition, since surface defects can be suppressed, the portion to be scraped off by machining after casting can be reduced, so that the cost related to the casting material can be reduced and it can contribute to environmental conservation.
Moreover, the casting_mold | template 10 of the said structure can divert the casting_mold | template currently used for the conventional full mold casting as it is. Therefore, it is possible to improve the quality of the cast product without incurring costs for the equipment.

Sectional drawing which showed the whole structure of the casting_mold | template for full mold casting which concerns on the Example of this invention. Sectional drawing which showed another form of the casting mold for full mold casting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 11 Casting frame 12 Cast sand 13 Disappearance model 14 Pouring gate 15 Runway 16 Exhaust pipe 17 Exhaust hole

Claims (2)

In a mold that is used for full mold casting, in which molten metal is poured into a mold formed by burying a disappearance model in casting sand, and the product is cast while vaporizing and disappearing the disappearance model with the molten metal,
Arrange the disappearance mold so that its longitudinal direction is substantially vertical,
An exhaust pipe that connects the upper part of the disappearance model and the outside of the mold is provided.
A full mold casting mold characterized in that an exhaust hole is formed in the sand for communicating the disappearance model with the outside of the mold. The disappearance model is made of acrylic resin.
The mold for full mold casting according to claim 1.

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