JPH01186241A - Lost wax pattern for casting - Google Patents

Abstract

PURPOSE:To facilitate manufacture of a lost wax pattern and to reduce the labor by integratedly forming a runner part extending from a main body part made of expandable synthetic resin and an engaging part fitting the runner part to a runner tube for molten metal passage with the main body part. CONSTITUTION:The runner tube 10 is invested in a sand mold and used to the molten metal passage and made to cylindrical shape with heat resistant metal or ceramic, etc., and conical shape at the upper end fixed to a bottom plate 12 at the lower end to stably support the runner tube 10. Further, plural inserting holes 13 penetrating the tube wall are arranged at side part. On the other hand, the lost wax pattern forms the pattern main body 14 corresponding to the casting and a gate 15 integratedly set with the pattern main body 14 and a stopper 16 for connecting the pattern main body 14 with the runner tube 10 by engaging with the inserting hole 13 in the runner tube 10 at the tip part thereof. Therefore, the lost wax pattern is fitted to the pattern main body 14 by engaging the stopper part 16 with each inserting hole 13 and can be used by investing in the sand as a tree.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a vanishing model for casting, and particularly to a vanishing casting model in which a runner part and a model main body part are constructed separately.

``Prior art'' The conventional casting method using a vanishing model for casting involves embedding a vanishing model made of resin such as styrofoam or urethane foam in a sand mold, and injecting molten metal (hereinafter referred to as molten metal) into the sand mold. , the vanishing model is vaporized or combusted and gasified and replaced with the molten metal while being discharged through the sand grains to obtain a casting having the same shape as the vanishing model in the sand mold, and is widely used in the manufacture of precision parts, etc. Applied.

In addition, when attempting to cast relatively small mechanical parts, etc., in order to improve work efficiency, as shown in FIG. (that is, parts of shapes corresponding to the parts themselves to be manufactured) are glued together to form a disappearing model called a Styrofoam tree, and a metal sprue cup 4 is attached to the top of the rod-shaped part l of this tree. After that, the tree is placed in a mold 5 and filled with sand (so-called sand filling) to form a sand mold 6, and molten metal (hereinafter referred to as molten metal) is poured from the sprue cup 4. The method used is to obtain castings by injecting.

That is, when molten metal is injected from the sprue cup 4, first, the Styrofoam constituting the rod-shaped portion I is decomposed by the heat of the molten metal, so that a runner corresponding to the shape of the rod-shaped portion I is sequentially formed. Molten metal is supplied to each model body 3 through a runner having a shape corresponding to the part 2, and the foamable synthetic resin constituting this is replaced with the molten metal, and a casting having a shape corresponding to the tree is formed in the sand mold 6. be done.

"Problem to be Solved by the Invention" By the way, when using a disappearing model with the above structure, a large number of branches are glued to the trunk part, and not only the model body 3 but also other trunks (attached parts) are attached. ) It is also necessary to apply a mold release agent to the surface of the part, and then wait for the adhesive to harden before filling with sand, so there is a problem in that it takes time and effort to produce the disappearing model. In addition, during casting, it is necessary to decompose not only the Styrofoam of the model body but also the part corresponding to the trunk, so carbon or carbon compounds produced by decomposing the Styrofoam may adhere to the surface of the part and cause carburization. There is also the possibility that defects may be caused by carbon residue or carbon residue.

The present invention has been proposed in view of the above-mentioned circumstances, and aims to obtain a vanishing model that is easy to manufacture and that can change the amount of carbon generated during vanishing.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides a casting casting model that is embedded in a sand mold to form a cavity, and extends from a main body made of a foamable synthetic resin to form a runner. and an engaging part that fits and attaches the runner part to a passage for molten metal poured into a mold, and the runner part and the engaging part are integrated with the main body part. It is molded from foamable synthetic resin.

"Function" With the above configuration, a tree is formed by a simple procedure of fitting the engaging portion to a molten metal discharge port provided in a runner pipe that is buried in a sand mold and serves as a path for molten metal. be able to. In addition, the formed tree is used by being buried in sand like a conventional tree, and by pouring molten metal into the runner pipe, molten metal is supplied to each disappearing model body to replace the disappearing model body. Castings can be formed while

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

Reference numeral 10 in the figure is a runner. This runner pipe lO is buried in a sand mold and serves as a passage for the molten metal.It has an overall cylindrical shape and is made of a material such as metal or ceramic that has heat resistance that can withstand the temperature of the molten metal used. There is. Further, the upper end of the runner IO is open, and a sprue 11 formed in a cone shape and made of the same heat-resistant material as the runner IO is connected to this opening. On the other hand, the runner IO
A bottom plate 12 is fixed to the lower end of the sand mold to close the runner, and the bottom plate 12 can stably support the runner 10 within the sand mold. Furthermore, the runner pipe IO
An insertion port 13 that penetrates the tube wall in the radial direction is provided on the side of the tube.
There are several.

In addition, the vanishing model is made by heating and expanding a large number of particles of polystyrene foam, urethane foam, etc. to form a dense rock on the inside of the mold, and by melting them together and molding them into a predetermined shape. A model body 14 having a shape corresponding to the casting to be formed;
A weir 15 is integrally connected to the weir 15. As shown in FIG. 2, the weir 15 has a cross-sectional shape corresponding to the width W and height of the insertion port 13, and has a runner pipe around the insertion port 13 at its tip. l
A pullout stop 16 is formed which engages with O to connect the model body 14 to the runner pipe 10. Note that the removal stopper 16 has a width equal to that of the insertion port 13 and a height a of the distal end and a height b of the base end thereof so that it can engage with the insertion port 13. mouth! a< for the height h of 3
It is set so that h<b holds true.

The disappearance model configured as described above has each insertion port 13.
While engaging the pull-out stops 16 respectively, remove the model body 14.
After applying a mold release agent to the surface of the model body 14 and the weir I5 (the mold release agent may be applied before installation), the conventional disappearing model is made. It is used filled with sand in the same way. In addition, a bottom plate 12 is attached to the base end of the runner pipe 10, and since the main runner pipe 10 has a sufficiently large weight compared to the disappearing model, it is necessary to place it in the formwork in order to fill it with sand. It is extremely stable when placed, and therefore is less likely to shift during sand filling.

Then, after pouring the sand, pour the molten metal from the Moeki sprue It.
This molten metal passes through the runner pipe 10 and is discharged to the outside from each insertion port 13 while decomposing and disappearing the foamed resin in the portion corresponding to the stopper 16. The released molten metal decomposes the foamed resin in the part corresponding to the weir 15 and reaches the part corresponding to the model body 14, and then decomposes the foamed resin in this part and replaces it, filling the cavity in the sand mold. It is molded into a shape. In addition, the foamed resin decomposed by contact with the molten metal produces hydrocarbons as a gas,
Alternatively, the carbon dioxide, carbon oxide, and water (steam) produced by decomposition of this material are released into the atmosphere through the sand grains that make up the sand mold.

"Effects of the Invention" As is clear from the above description, the present invention has the following effects.

a. A tree can be easily formed by sequentially attaching the disappearing models to the runner pipes that are buried in the sand mold and serve as passages for the molten metal, and the labor required for producing the disappearing models is reduced.

b. Because the runners are made of heat-resistant material, there is less foaming of the foamable synthetic resin in the sand mold, and therefore the amount of carbon to be decomposed is also reduced, reducing the amount of various types of carbon caused by residual carbon. Defects are less likely to occur.

Since the heat-resistant material constituting the C0 runner pipe is generally heavier than the foamed resin, the tree is stable and less likely to fall over or become misaligned when filled with sand.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
Figure 1 is a perspective view showing the appearance of the tree, Figure 2 is an enlarged perspective view showing the structure of the runner pipe and the model body in detail, and Figure 3 is a diagram showing a conventional disappearing model buried in a sand mold. FIG. 10... runner pipe (molten metal passage), 11...
... Sprue, 12... Bottom plate, 13... Inlet, I4... Model body, 15...
・Weir, 16... Stop pulling out.

Claims (1)

[Claims] It consists of a runner part that extends from a main body made of foamable synthetic resin to form a runner, and an engaging part that fits and attaches the runner part to a passage for molten metal poured into a mold. A vanishing model for casting, characterized in that a channel portion and an engaging portion are also molded from a foamable synthetic resin integral with the main body portion.