JPH06254655A - Gypsum mold for precision casting and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the misrun caused by leakage of molten metal and to eliminate the need of cleaning work for the solidified metal of the leaked molten metal by preventing the generation of the leakage of molten metal without using a separated mold and an inserting sleeve for arranging a sprue. CONSTITUTION:A casting cavity 2 is provided and also a runner 3 and the sprue 4 communicated with the casting cavity 2 are provided. Then, the casting cavity 2 and the sprue 4 are formed in the inner part of a mold main body 5 and the sprue wall 6 integrally formed with a hardened gypsum. Further, the runner 3 is formed at the W part between the mold main body 5 and the sprue wall 6 integrally formed with the hardened gypsum to obtain the gypsum mold 1 for precision casting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision casting gypsum mold suitable for use as a gypsum mold used in the production of precision castings, and a precision casting gypsum mold suitable for producing the gypsum mold. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art A gypsum mold, which is a type of precision casting mold, is made of gypsum and has curved surfaces and fine irregularities that are difficult to machine, and also requires high dimensional accuracy. Suitable for precision casting of certain things.

Conventionally, when manufacturing such a gypsum mold, for example, as shown in FIG. 8 (a), a gate 52 is placed on a gate forming platen 51 and a gate model is formed. After installing 53, calcined gypsum (CaSO ₄ 1 / 2H ₂ O), water, etc. (that is, talc for preventing mold cracking, hardening accelerator, hardening retarder, Silica sand, lime, etc. may be added in some cases.) Pour the muddy gypsum 54 and let it stand, etc.
SO ₄ · 2H ₂ O) to harden it, and then bake it if necessary to fabricate a sprue mold 57 having a sprue 55 and a runner 56, as shown in FIG. As shown in (b) of FIG. 1, after the mold forming flask 62 is installed on the mold forming platen 61 and the product model 63 is installed, calcined gypsum, water, etc. are placed in the mold forming mold 62. As shown in FIG. 9, a casting space 65 and a runner 66 are provided by pouring mud-shaped gypsum 64 in which is mixed with, and curing by leaving it to be gypsum, and then firing as necessary. The product mold 67 was manufactured. Then, when manufacturing a casting, as shown in FIG. 9, a sprue mold 57 is installed on a product mold 67 to make the casting space 65 and the sprue 55 communicate with each other through the runners 56 and 66. By casting the molten metal more and solidifying it in the casting space 65, a casting having the same shape as the product model 63 is manufactured.

Further, in the case of such a conventional precision casting plaster mold, in consideration of the fact that both the sprue mold 57 and the product mold 67 are manufactured in substantially the same process, the product mold 67 is left as it is. As a result, by adopting a casting method that does not use the sprue mold 57, measures have been taken to reduce the cost.

FIGS. 10 and 11 show a conventional technique in which such measures are taken. As shown in FIG. 10, a casting frame 72 is installed on a mold forming surface plate 71 and the product is After installing the model 73, a mud plaster 74 that is a mixture of calcined gypsum and water is poured into the casting frame 72, and after calming, the upper model 75 having an annular convex portion 75a on the bottom is used. The annular convex portion 75a of 75 is replaced with a muddy plaster 74
The mold main body having a casting space inside the mold and an annular recess formed on the upper surface is produced by immersing the muddy gypsum 74 in the mold I was trying to do it.

When a casting is produced using such a mold, as shown in FIG. 11, a plaster mold body having a casting space 82, a runner 83, and an annular recess 84 on a surface plate 81, as shown in FIG. 85 is installed, and the sleeve 86 is provided in the annular recess 84.
Is cast into the sleeve 86 to form a gate 87, and then a molten metal is injected from the gate 87 and solidified in the casting space 82 to produce a casting having the same shape as the product model 73. I was trying to do it.

[0007]

However, in such a conventional gypsum casting mold 85 for precision casting, when pouring the molten metal from the sprue 87, it cannot be said that the sleeve 86 may not fall down, and the annular shape Recess 84 and sleeve 8
There is a problem that hot water may leak from the gap between the lower end of the sleeve 6 and the sleeve 8.
When Tipping of No. 6 and leakage of molten metal occurred, there were problems such as interruption of casting, defective running of the molten metal, and troublesome treatment of the solidified metal generated by the leakage of molten metal.

Therefore, there has been a problem that there is a demand for development of a precision casting gypsum mold and a method for manufacturing the same, which does not have such problems and can reduce the cost.

[0009]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above-mentioned conventional problems, and eliminates the use of an insertion sleeve as a sprue, and also causes the occurrence of hot water leaks, poor run around due to hot water leaks, and hot water leak coagulation. An object of the present invention is to provide a plaster mold for precision casting and a method for manufacturing the same, which can eliminate the work of cleaning the metal.

[0010]

A plaster mold for precision casting according to the present invention has a casting space and a sprue communicating with the casting space, and the casting space and the sprue are integrally molded with hardened gypsum. It is characterized in that it is formed inside each of the cast main body and the sprue wall.

In a preferred embodiment of the plaster mold for precision casting according to the present invention, a concave pocket is formed on the outer side of the sprue wall in which the sprue is formed and on the upper side of the mold body. Can be

Further, in the method for producing a plaster mold for precision casting according to the present invention, the product model is installed inside a casting frame having a mold forming space with a closed bottom, and the gate model is connected to the product model, After inflowing the muddy gypsum into the mold forming space, lower the upper model having a sprue wall forming portion that forms a sprue wall with the sprue model into the muddy gypsum, and in a state where the mud gypsum is hardened. , The mold body is formed by the bottom of the upper model and the casting frame, the casting space of the mold is formed by the product model, and the sprue wall of the mold is formed by the sprue wall forming part of the upper model and the sprue model. It is characterized in that the gate of the mold is formed.

In the embodiment of the method for producing a plaster mold for precision casting according to the present invention, a convex portion for forming a concave pocket is formed on the bottom surface of the upper model, and the convex portion for forming a concave pocket forms an upper portion of the mold body. A concave pocket can be formed on the side and outside the sprue wall.

[0014]

In the plaster mold for precision casting according to the present invention, since the casting space and the sprue are formed inside the mold body and the sprue wall which are integrally molded with hardened plaster, the molten metal is used When pouring from the mold body, the sprue wall integrally molded with the mold body does not fall down as in the case where the sprue is formed by using a separate insertion sleeve, and there is also a leakage of melt at the connection part with the mold body. Never. Further, since the molten metal can be rapidly injected without leaking, there is no possibility of defective molten metal running, and the need for cleaning the solidified metal caused by the leaking of molten metal is eliminated.

Further, in the method for producing a plaster mold for precision casting according to the present invention, a product model is installed inside a casting frame having a mold forming space with a closed bottom, and a sprue model is connected to the product model to form a mold. After the mud gypsum has flowed into the molding space, the upper model having a sprue wall forming portion that forms a sprue wall with the sprue model is left as it is in a state of being dropped into the mud plaster to form gypsum. Since it is intended to harden, an integrated precision plaster model for precision casting in which the casting space and the sprue are formed inside the mold body and sprue wall integrally formed by the cured plaster is manufactured at low cost. It will be.

[0016]

FIG. 1 shows an embodiment of a precision casting gypsum mold according to the present invention. This precision casting gypsum mold 1 is provided with a casting space 2 and is provided in the casting space 2. A sprue 4 communicating with a spout 3 is provided, and the casting space 2 and the sprue 4 are formed inside a mold body 5 and a sprue wall 6 which are integrally formed of hardened gypsum, respectively. The passage 3 is formed inside the transition portion between the integrally molded mold body 5 and the sprue wall 6, and
A concave pocket 7 is formed outside the gate wall 6 and on the upper side of the mold body 5.

When a casting is manufactured using such a precision casting gypsum mold 1, the precision casting gypsum mold 1 is used.
Is installed on the surface plate, and if necessary, a mold frame is provided on the side surface, and then molten metal is injected from the sprue 4, the casting space 2 is filled with the molten metal through the runner 3, and after solidification, the mold By performing the disassembling, a casting having the same shape as the casting space 2 is manufactured.

Next, when manufacturing the above-mentioned plaster mold 1 for precision casting, as shown in FIG. 2, a sprue wall forming portion having a shape corresponding to the outer shape of the sprue wall 6 of the mold 1 is formed at the center portion. 11a and an upper model 11 having a concave pocket forming convex portion 11b having a shape corresponding to the concave pocket 7 of the mold 1 on the bottom surface, and as shown in FIG. A sprue model 12 having an outer shape corresponding to the shape of the sprue 4 and having a product model engaging portion 12c at the lower end, and a mold having a shape corresponding to the outer shape of the mold 1 as shown in FIG. A flask 13 having a space 13a,
As shown in FIG. 5, the casting mold 1 has a product shape portion 14a having the same shape as the casting to be manufactured.
1 has a runner forming portion 14b having a shape corresponding to the runner 3 of
At the upper end of the runner forming portion 14b, the gate model engaging portion 14 that engages with the product model engaging portion 12c formed on the gate model 12 is formed.
A product model 14 having c is used.

Then, as shown in FIG. 6, the product model 14 is installed on the surface plate 15, the casting frame 13 is installed concentrically with the product model 14, and the gate model 12 is moved in the direction of arrow A. To engage the gate model engaging portion 14c of the product model 14 and the product model engaging portion 12c of the gate model 12,
After connecting the product model 14 and the sprue model 12, calcined gypsum (CaSO ₄ 1 / 2H ₂ O), water, etc. (that is, talc for preventing cracks in the mold, hardening accelerator, A hardening retarder, silica sand, lime, etc. may be added.) Pour the mud gypsum mixed with the above, and when the mud gypsum is in a sedative state, the upper model in the direction of arrow B shown in FIG. 11 is lowered, and as shown in FIG. 7, a mud-shaped gypsum 17 is formed on the upper model 11 to form a concave pocket forming convex portion 11b.
Of the gypsum (CaSO ₄₎ by raising the mud gypsum 17 between the sprue wall forming portion 11a formed on the upper model 11 and the sprue model 12, and leaving it in this state.
2H ₂ O), and the bottom of the upper model 11 and the casting frame 13 form the mold body 5 and the product model 14 forms the casting space 2 of the mold 11, and the sprue wall forming portion 11a of the upper model 11 is formed. And the sprue model 12 form the sprue wall 6 of the mold 11, the sprue model 12 forms the sprue 4 of the mold 11, and after drying or firing (that is, anhydrous gypsum) as necessary, the casting frame 13 After removing the upper model 11, the product model 14, and the sprue model 12, the plaster mold 1 for precision casting shown in FIG. 1 is obtained.

Further, when a surface active agent or the like is mixed with gypsum and foamed with air for use in molding, a mold having good air permeability can be manufactured.

[0021]

According to the plaster mold for precision casting according to the present invention, the use of the sprue mold and the fitting sleeve for forming the sprue is eliminated, and the mold having the spout integrated with the mold body is used. Therefore, there is no need to manufacture a sprue mold or a sleeve, the interruption of the casting operation due to the fall of the fitting sleeve at the time of pouring the molten metal is eliminated, and the occurrence of hot water leakage at the fitting portion of the sleeve is eliminated.
It is possible to obtain a remarkably excellent effect such as a poor running around the molten metal caused by the molten metal leak and the elimination of the cleaning work of the solidified metal generated by the molten metal leak.

[Brief description of drawings]

FIG. 1 is a left-half vertical sectional side view showing an embodiment of a precision casting gypsum mold according to the present invention.

FIG. 2 is a left side vertical cross-sectional side view of an upper model used for manufacturing a plaster mold for precision casting according to the present invention.

FIG. 3 is a left side vertical sectional side view of a sprue model used for manufacturing a plaster mold for precision casting according to the present invention.

FIG. 4 is a left side vertical cross-sectional side view diagram of a casting frame used for manufacturing a precision casting gypsum mold according to the present invention.

FIG. 5 is a left side vertical sectional side view of a product model used for manufacturing a plaster mold for precision casting according to the present invention.

FIG. 6 is a cross-sectional explanatory view showing a state in the first half step (before the inflow of muddy gypsum) of manufacturing a plaster mold for precision casting using each jig shown in FIGS. 2 to 5;

FIG. 7 is a cross-sectional explanatory view showing a state in a latter half step (after inflowing muddy gypsum) of manufacturing a precision casting gypsum mold using each jig shown in FIGS. 2 to 5;

FIG. 8 shows an example of a conventional method for producing a plaster mold for precision casting, which includes a sprue mold ((a) of FIG. 8 and a product mold (FIG. 8).
It is sectional explanatory drawing which shows the state which manufactures (b) of this separately.

9 is a cross-sectional explanatory view showing a state in which the sprue mold and the product mold of FIG. 8 are combined to form a plaster mold for precision casting.

FIG. 10 is a cross-sectional explanatory view showing a state in the middle of manufacturing a precision casting gypsum mold in another example of the conventional method for manufacturing a precision casting gypsum mold.

FIG. 11 is a cross-sectional explanatory view of a mold in which a mold body manufactured according to FIG. 10 is provided with a gate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gypsum mold for precision casting 2 Casting space 3 Runner 4 Gate 5 Mold body 6 Gate wall 7 Concave pocket 11 Upper model 11a Gate part forming part 11b Convex part for forming concave pocket 12 Gate model 12c Product model engaging part 13 Casting frame 13a Mold forming space 14 Product model 14a Product shape part 14b Runner forming part 14c Gate model engaging part 17 Mud gypsum

Claims (4)

[Claims] 1. A casting space is provided, and a sprue communicating with the casting space is provided. The casting space and the sprue are formed inside a mold body and a sprue wall integrally formed of hardened gypsum, respectively. A plaster mold for precision casting characterized by the above. 2. The gypsum mold for precision casting according to claim 1, wherein a concave pocket is formed on the outer side of the sprue wall in which the sprue is formed and on the upper side of the mold body. 3. A product model is installed inside a molding frame having a mold forming space with a closed bottom, a sprue model is connected to the product model, and mud gypsum is introduced into the mold forming space. The upper model, which has the sprue wall forming part that forms the sprue wall with the sprue model, is lowered into the mud plaster, and when the mud plaster is hardened, the mold body is formed by the bottom surface of the upper model and the flask. In addition, the casting space of the mold is formed by the product model, and the gate wall of the mold is formed by the gate wall forming part of the upper model and the gate model, and the gate of the mold is formed by the gate model. Manufacturing method of gypsum mold. 4. The convex pocket forming convex portion is formed on the bottom surface of the upper model, and the concave pocket forming convex portion forms a concave pocket on the upper side of the mold body and outside the sprue wall. For manufacturing a plaster mold for precision casting.