JP2842082B2 - Vanishing model for precision casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick-walled conical shape.
The present invention relates to a precision casting vanishing model used for manufacturing a precision casting mold used for manufacturing a precision casting having a base .

[0002]

2. Description of the Related Art There are various types of precision casting methods employed in the production of precision casting products, such as a die casting method, a low pressure casting method, a shell mold casting method, a lost wax casting method, a full mold casting method, and the like. In the lost wax casting method and the full mold casting method, a precision casting product is manufactured by manufacturing a precision casting mold using a vanishing model using a vanishing material.

[0003] In this case, the vanishing model used in the lost wax casting method is manufactured by injection-injecting a semi-molten state wax or a water-soluble urea resin into a cavity of a vanishing model molding die (see FIG. 1). For example,
"Revised 4th Edition Metal Handbook" Published December 20, 1982, edited by The Institute of Metals, Japan, pages 1513 to 151
6).

FIG. 2 shows a lost casting model for precision casting used for producing a precision casting mold used for precision casting of a hot wheel for a turbocharger. The lost casting model for precision casting is shown in FIG. 51 is provided with a plurality of blade portions 51b on the outer peripheral side of a thick base portion 51a having a substantially conical cross section, and has an injection portion 51c by injection molding on the small-diameter blade side, and has a shaft on the large-diameter blade side. The structure has a portion forming portion 51d.

[0005]

However, such a conventional vanishing model 51 for precision casting has a thick base 51a having a conical shape at the center thereof . In the cooling process during production, the heat shrinkage of the evaporable material may increase particularly in thick-walled parts, and the dimensional accuracy after shrinkage may be reduced. The problem is that the thermal expansion of the mold increases, especially in thick-walled parts, which may cause cracks in the mold. It has been a problem to solve problems such as a decrease in the dimensional accuracy and the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-mentioned problems, and it is intended to use a fugitive material and a cone.
For the shape of precision castings with thick bases
In evaporative pattern for precision casting having a thick-shaped base portion which forms a response to the conical shape, and prevent problems such as cracks and reduction in dimensional accuracy of the template by particularly thick thermal expansion and contraction of the fugitive material in a portion of the meat shape It is an object of the present invention to enable efficient casting of a precision casting having high dimensional accuracy.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a precision casting using a fugitive material and having a thick base having a conical shape.
In <br/> evaporative pattern for precision casting having a thick-shaped base portion which forms a conical shape corresponding to the shape of the goods, it a conical shape of the evaporative pattern
Inside the thick base having the conical shape.
Conical part for reducing thermal expansion and contraction with similar conical shape
The present invention is characterized by having a structure provided with a material , and is a means for solving the above-mentioned conventional problems with the structure of the invention relating to such a vanishing model for precision casting.

In the vanishing model for precision casting according to the present invention, wax or a water-soluble urea resin can be used as the vanishing material, and a circle for thermal expansion / shrinkage relaxation can be used.
Styrofoam, urethane foam , low thermal expansion coefficient, low melting point metal, and the like can be used as the material of the conical member , but the material is not limited to these materials.

[0009]

The vanishing model for precision casting according to the present invention is:
Since it has the configuration described above, it has a conical shape
The heat shrinkage of the vanishing material is arranged in the cooling process during the production of the vanishing model having a thick base
The thermal expansion / contraction relief cone reduces the amount of heat shrinkage due to the presence of the conical member , which reduces the decrease in dimensional accuracy after cooling and reduces the thickness of the cone.
Thermal expansion of heat-dissipating material similar to thermal expansion of heat-dissipating material during heating process of heat-dissipating model with fleshy base
It is alleviated by the presence of the conical member for relaxation of tension and contraction ,
Since the amount of thermal expansion is reduced, the occurrence of cracks in the mold at the time of demolding is prevented.

[0010]

FIG. 1 is an explanatory longitudinal sectional view of a vanishing model for precision casting according to the present invention, in which the precision casting is a hot wheel of a turbocharger.

The vanishing model 1 for precision casting shown in the figure has a blade portion 1 on the outer peripheral side of a thick base portion 1a having a substantially conical cross section.
The b together are plurality, the thermal expansion and contraction relaxation conical member 2 forming a conical shape similar to the conical shape inside a thick-shaped base portion 1a forming a conical shape provided, injection molding on the small diameter blade side And an axial portion forming portion 1d on the side of the large-diameter blade.
It has a structure in which a baseboard portion 2a integral with the conical member 2 is penetrated, and has a thick base portion 1a and a blade portion 1b.
Is formed of wax, and the conical member 2 and the baseboard portion 2a are formed of styrene foam.

When manufacturing the vanishing model 1 for precision casting having such a structure, as shown in FIG. 3, a molding space of the vanishing model forming die 3 (a conical shape corresponding to a hot wheel shape of a turbocharger) is formed. In a central portion of the molding space 3a for forming the thick base portion and the plurality of blade portions,
Conical for thermal expansion / shrinkage molding made of Styrofoam
The shaped member 2 is arranged and held by the baseboard portion 2a, and then a semi-molten wax (temperature of about 65 ° C.) is injected into the molding space 3a at an injection pressure of 70 kgf / cm ² , whereby the interior is formed. Conical shape for thermal expansion / shrinkage reduction
The vanishing model 1 made by casting the material 2 is manufactured.

At this time, after the semi-molten wax is injected and injected to cast the conical member 2 for thermal expansion / shrinkage relaxation, the wax undergoes a cooling process. As compared with the case where the conical member for alleviating thermal expansion / contraction is not provided, the buffering action of the conical member 2 further alleviates the thermal expansion and contraction. Is kept high.

The vanishing model 1 manufactured in this manner is obtained by removing a part of the baseboard portion 2a protruding from the runner bonding surface R, and then removing the rod-shaped runner (corresponding to the trunk of the tree) also manufactured by wax. And several vanishing models 1
(Corresponding to the branches and leaves of the tree) by welding and assembling into a wax tree, for example, by repeating the steps of dipping the wax tree into a binder slurry such as a colloidal silica-based slurry, sanding, and drying. A coating layer composed of a plurality of layers is formed. In this case, in the coating layer formed by sanding, zircon sand (# 80) is used as the first layer, and high alumina sand (0.3 to 0.7 mm) is used as the second to fifth layers. it can.

In this way, after the refractory coating is provided by repeating dipping, sanding, and drying in the slurry, the slurry is charged into an autoclave,
A demolding process is performed in which the wax is melted and dropped by heating at a temperature of 8 ° C., 8 kgf / cm ² , and a demolding condition of 10 minutes.

[0016] In the heating during the de-model, but the wax results in a thermal expansion of the wax thermal expansion of the conical member 2 than in the case without the conventional thermal expansion and contraction relaxation conical member It is alleviated by the buffering action, the amount of thermal expansion of the thick base 1a becomes small, and cracks hardly occur in the mold made of the refractory layer.

As described above, the dimension W in FIGS. 1 and 2 is -0.1 mm in the conventional case shown in FIG. In this case, the shrinkage amount is -0.05 mm, the shrinkage amount is smaller, a high dimensional accuracy can be obtained, and cracks may be visually observed in the conventional case in the mold check after the membrane model. On the other hand, in the case of the present invention, no crack was observed. Then, using such a high precision dimensional accuracy and crack-free precision casting mold, a plurality of hot wheels are cast by casting a molten metal such as a heat-resistant alloy into a cavity formed by demolding, Individual hot wheels could be obtained by demolding and cutting of the tree-shaped casting.

Similar results were obtained when a metal having a lower coefficient of thermal expansion than wax was used. Furthermore, as a result of a similar test using a cadmium alloy and a bismuth alloy, which are low-melting metals that melt at the same temperature as the wax, the shrinkage was -0.03 mm, and cracks were observed in the mold check. Did not.

[0019]

According to the vanishing model for precision casting using the vanishing material according to the present invention, the cone-shaped thickness of the vanishing model is obtained.
Similar to the thick-like base portion which forms the conical shape inside a meat-like base portion
Because has a structure in which a thermal expansion and contraction relaxation conical member having a conical shape, in particular thick-like group forming a conical shape
Thickness with the conical shape in a vanishing model having a part
By providing a conical member for reducing thermal expansion and contraction inside the base portion, the heat shrinkage of the vanishing material, particularly in the thick portion, is reduced by the presence of the conical member during the cooling process during model molding. As a result, the amount of heat shrinkage of the fugitive material becomes small, the dimensional accuracy of the fugitive model after cooling becomes higher, and in the heating process at the time of demolding, the fugitive material, especially in a thick part, The thermal expansion is conical
The resilience is reduced by the presence of the shaped member , so that the amount of thermal expansion of the fugitive material is reduced, and a remarkably excellent effect that cracks do not occur in the mold after the demolding is provided.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view of a vanishing model for precision casting according to an embodiment of the present invention.

FIG. 2 is an explanatory longitudinal sectional view of a vanishing model for precision casting according to a conventional example.

FIG. 3 is an explanatory view of a slope of a disappearing model forming die for precision casting.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 vanishing model for precision casting 1a thick base 2 core for thermal expansion / shrinkage relaxation

Claims (1)

(57) [Claims] 1. A thickness using a fugitive material and having a conical shape.
Conical shape corresponding to the shape of precision casting with fleshy base
In evaporative pattern for precision casting having a thick-shaped base forming the Jo, the inside of the thick-shaped base portion which forms the conical shape of the evaporative pattern
A vanishing model for precision casting, comprising a conical shaped member for thermal expansion / shrinkage reduction having a conical shape similar to a thick base having a conical shape .