JPS61279337A - Molding method for shell mold for casting - Google Patents

Abstract

PURPOSE:To strengthen a casting mold by mounting reinforcing materials to the desired points of a pattern tree, etc. and forming a shell layer. CONSTITUTION:Many consumable patterns 2 each consisting of a urea resin material, etc. are attached to a stem part 1 to form the tree 3 and a wire net 5 made of a stainless steel, etc. is wound to the root part 4 thereof. The tree 3 is immersed into a slurry contg. zircon and a stuccoing material is stuck thereto. The operation is repeated plural times to form the shell layer 6. The tree 3 is then melted by heating and is removed and further the urea resin material is thoroughly consumed by heating, by which the shell mold 6 is formed. Since the stainless steel wire net 5 is mounted to the part 7 vulnerable to breakage of the shell mold 6, the strength of the casting mold is improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a shell mold.

(Prior Art) Generally, a ceramic shell mold is formed by an investment casting method, for example, as follows. That is, a model tree with a large number of fugitive models, such as wax models, is immersed in a slurry consisting of a refractory binder and refractory powder, then inserted into a fluidized bed of stucco material, and a refractory material is placed on top of the slurry. After repeating the operation of depositing a stuffing material made of powder to form a shell layer usually 5 to 7 times, the shell layer is fired while drying to form a ceramic shell mold.

After the ceramic shell is formed on the surface of the model, the fugitive model is melted out by heating, for example, and then fired.

In such a shell mold manufacturing method, when it is desired to increase the strength of the obtained shell mold, the following method has conventionally been adopted.

(1) Increase the number of coatings, ie, dipping into the slurry, depositing the stucco material, and then forming a shell layer by drying and curing the slurry.

(2) Increasing the strength of the shell layer by increasing the viscosity of the slurry.

(3) Increase the strength of the shell layer by using a slurry containing reinforcing materials such as reinforcing fibers.

(4) Increase the strength of the shell layer by increasing the grain size of the stuff material.

(5) After forming the mold, it is further immersed in slurry, dried and hardened to be reinforced.

However, when using any of the methods (1) to 5) above, the slurry becomes unstable, resulting in a shortened service life, or the curing properties of the slurry become insufficient; the weight of the mold increases; Since not only the parts desired to be strengthened but also unnecessary parts are strengthened, the sand removal property when the mold is broken becomes worse; it takes a lot of time to make the mold; There were problems such as, depending on the shape, it may not be possible to mold it.

(Problems to be Solved by the Invention) Therefore, the present invention has been made to solve the above-mentioned problems without increasing the number of coatings or changing the properties of the slurry or stucco material. In addition, it is an object of the present invention to provide a method for manufacturing a shell mold that can strengthen only the portion where the strength is desired to be improved.

(Means for Solving the Problems) The shell mold manufacturing method of the present invention involves depositing refractory slurry and stucco material alternately on a fugitive model tree a predetermined number of times to form a shell layer, and then drying and firing. When molding a shell mold, reinforcing materials are attached to desired locations of the model tree or the shell layer to be formed to form the shell layer.

The fugitive model, the refractory slurry, the refractory powder used as the stucco material, etc. used in the present invention can be those conventionally used in this type of technical field, and the shell forming method can be carried out by conventional methods. be able to.

According to the investment casting method, which uses a model made of a fugitive material such as wax as the fugitive model, the model can be easily removed after the shell mold is formed by, for example, heating and melting it.

When molding a ceramic shell mold as the shell mold, for example, a refractory slurry consisting of a refractory binder and refractory powder is used. Colloidal silica, ethyl silicate, etc. are usually used as the refractory binder, and the refractory powder is usually 350 to 400%
Use mesh zircon, fused silica, fused alumina, etc. As the stucco material, refractory powder such as fused silica, mullite, /\alumina sand, etc. is used.

To apply the stucco material, it is convenient, for example, to use a fluidized bed.

In the present invention, the reinforcing material is not particularly limited, but includes, for example, asbestos, ceramic fiber, glass fiber,
Fibers such as carbon fibers and metal fibers or woven fabrics thereof, or wire meshes made of ferrous metals or stainless steel can be used. However, ceramic fibers and stainless steel wire gauze are particularly preferred from the viewpoint of fire resistance.

Installation of reinforcing material 1. Normally, the part of the mold that you want to strengthen is not the model part of the model tree, but the part of the trunk where the model is attached or the part that connects the model and the trunk, so such parts are not directly reinforced. Wrap wood fibers, woven fabric, wire mesh, etc. Further, in areas where it is difficult to directly wrap the shell layer, the shell layer is formed once or several times, the reinforcing material is attached, and then the shell layer formation is repeated.

(Example) Below, a method for manufacturing a shell mold of the present invention will be described with reference to the drawings.

As shown in Figure 1, a tree-shaped model (hereinafter referred to as a tree) 3 has a tree shape model (hereinafter referred to as a tree) 3 with a 40X
A stainless steel wire mesh 5 with 6 meshes each having a size of 47 mm is wrapped around it.

The tree 3 wrapped with the wire mesh described above is immersed in an ethylsilicate slurry containing ethylsilicate as a refractory binder and 325 to 400 mesh zircon as a refractory powder, and the tree 3 is made of high alumina sand. Apply stucco material. This operation is repeated six times to form six shell layers 6 as shown in FIG.

Finally, the tree 3 is melted and removed by heating, and then the urea-based resin material is completely disappeared by heating, and the shell layer is fired to form a shell mold.

The shell mold 6, which has been molded in a similar manner, has a stainless steel wire mesh 5 wrapped around the root portion 4 of the tree 3.
Since it is attached to the constricted part 7 of the shell mold 6 that is prone to mold breakage, it has sufficient strength and does not cause problems such as breakage during handling or pouring.

YoJJ nine urea resin tree 3 is dipped in slurry, and this tree 3
Step 3: Apply stucco material to form a shell layer.
3 times, then a circular 6-mesh stainless steel gold fIA 8 with a diameter of 50+ am is attached to the top 9 of the tree 3 covered by this shell layer as shown in FIG.

Further, the application of the immersion stucco material to the slurry is repeated three times in the same manner as described above to form a total of six shell layers.

Finally, as in Example 1, the tree with the shell layer formed thereon is heated to remove the tree 3, and the urea resin is completely burned off.

In the shell mold 10 formed in this way,
Since the stainless steel wire mesh 8 is attached to a portion where mold cracking is likely to occur during casting, such a problem does not occur.

In this example, the stainless steel wire mesh 8 used as the tree 3, slurry, stucco material, and reinforcing material had the following shapes other than the shape of the stainless steel wire mesh 8, considering the convenience of comparing the characteristics of the molded shell molds. The same material as in Example 1 was used.

Man-hour J For comparison, shell molds similar to those of Examples 1 and 2 above were molded under the same conditions without using any reinforcing material.

The shell molds of Example 1, Example 2, and Comparative Example were prepared in this way, and these molds were used for casting products under the same conditions. The incidence of cracking is shown in the table below.

As can be seen from the table above, no mold breakage or mold cracking occurred in the shell molds reinforced with stainless steel wire mesh 5 or 8.

Of course, the quality of the products cast with the shell molds of Examples 1 and 2 was the same as the quality of the products cast with the shell molds of Comparative Example.

(Effects of the Invention) According to the method for manufacturing a shell mold of the present invention, the shell can be formed without increasing the number of coatings for forming a shell layer or changing the properties of the slurry and/or the star 2-coated material. Since the strength of only the desired parts of the mold is improved, the weight of the mold does not increase unnecessarily, the life of the slurry does not decrease, and the working time for molding is lengthened. In addition, since this molding method can strengthen only the desired parts of the mold, sand removal properties will not deteriorate; By doing so, it is not restricted by the shape of the mold, and it is possible to easily strengthen the shell mold at any time.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a top view and a front sectional view showing a method for strengthening the shell mold of Example 1. FIG. 2 is a front sectional view showing the shell mold of Example 1, and FIG. 3 is a front sectional view showing a method for strengthening the shell mold of Example 2. 1... Trunk 2... Vanishing model 3... Tree shape model (tree) 4... Wood board part 5°, 8... Stainless steel wire mesh 6.10... Shell mold 7.・Part 9 where mold breakage is likely to occur ・Top fang 1 diagram (a)

Claims (1)

[Claims] When forming a shell mold by depositing refractory slurry and stucco material alternately on a fugitive model tree a predetermined number of times to form a shell layer, then drying and firing the shell layer, the model tree or the formed shell layer is formed. A method for manufacturing a shell mold, comprising: forming a shell layer by attaching a reinforcing material to a desired location of the shell layer.