JPH0442104B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing a mold used for casting a product having an uneven outer peripheral surface.

Conventionally, as a manufacturing method for this type of mold, a hollow elastic model made of rubber or other elastic material with an uneven outer circumferential surface corresponding to the product shape is prepared, and a fluid such as air or sand is injected into the elastic model. After filling the granules, a molding material such as foundry sand is filled around the granules and hardened, and then the filler inside the elastic model is discharged and the elastic model is deformed using its elasticity while being released from the mold. There are known molds in which a mold is manufactured by using a mold (see JP-A-52-21217 and JP-A-55-30340). In relation to using a fluid consisting of
The shape of the elastic model is not uniformly determined, which is a disadvantage that it is not suitable for manufacturing molds that require a high degree of dimensional accuracy.

In order to solve this problem, it may be possible to fit the core metal into the elastic model and hold it in a fixed shape, but in this case, when the mold material is filled and hardened, the elastic model will be crimped to the core metal. This makes it difficult to pull out the core metal from the elastic model.
It is necessary to solve this problem.

The purpose of the present invention is to solve the above problems and provide a manufacturing method that enables manufacturing a high-precision mold by keeping the shape of an elastic model with a cored metal. In a method of manufacturing a mold, in which a hollow elastic model having an uneven outer circumferential surface corresponding to the shape of the product is used to manufacture a casting mold for a product having unevenness, the mold is fitted into the elastic model and used to form a regular product. Prepare a core metal to hold the shape,
With the cored metal fitted into the elastic model, a mold material is filled around the elastic model and hardened, and then the cored metal is filled with the elastic model and pressurized from inside with fluid pressure. After the material is pulled out from the elastic model, the elastic model is contracted and deformed to be released from the mold.

The second invention aims to provide a manufacturing apparatus used for carrying out the method of the invention,
An apparatus for manufacturing a casting mold for a product having an uneven outer circumferential surface, comprising a hollow elastic model having an outer surface unevenness corresponding to the shape of the product, and a filling mold for mold material that accommodates the elastic model in a freely removable manner. A core metal that fits into the elastic model and holds it in the regular product shape is provided in a manner that can be freely inserted into and removed from the elastic model. It is characterized in that a through hole is formed so that a fluid pressure source can be freely connected to the fluid passage.

A third aspect of the present invention is that when releasing the elastic model in the method of the present invention, when the inside of the elastic model is contracted and deformed by applying negative pressure, the durability of the elastic model can be improved by preventing the elastic model from being excessively contracted. The purpose is to provide a manufacturing apparatus in which the core metal is formed into a cylindrical shape, and an auxiliary core metal is provided on the inner periphery of the core metal to be inserted into the elastic model. The present invention is characterized in that a fluid passage and a through hole on the outer surface are formed, and a fluid pressure source and a negative pressure source can be selectively connected to the fluid passage.

Next, the present invention is applied to the manufacture of a mold used for casting a product w such as an engine cylinder liner, which has irregularities a consisting of a large number of protrusions on the outer circumferential surface as shown in FIGS. 1 and 2. This will be explained in conjunction with the examples shown below. Incidentally, the unevenness a may have any shape as shown in FIGS. 3a to 3c. In Fig. 4, 1 is a filling opening 1a for mold material such as foundry sand on the top surface.
a filling mold that opens downward and is movable up and down;
shows a hollow elastic model made of rubber or other elastic material having irregularities 2a on the outer peripheral surface corresponding to the product shape, and the elastic model 2 is placed in the filling mold 1 at the opening 2b at the lower end and the flange 2c at the outer periphery. The elastic model 2 is fixed to a fixed frame 3 provided oppositely to each other, and the elastic model 2 can be freely inserted into and removed from the filling mold 1 by the vertical movement of the filling mold 1. A core metal 4 is provided to fit and hold the product in a regular product shape, and the core metal 4 can be inserted into and removed from the elastic model 2 from the opening 2b at the lower end of the elastic model 2, for example.
In addition, the core metal 4 has an internal fluid passage 5 and the fluid passage 5.
In the illustrated example, a large number of through holes 6 are formed extending from the upper surface of the core metal 4 to the outer circumferential surface thereof.

Further, in the illustrated example, the elastic model 2 is formed into a shape that is smaller than the regular product shape by at least the height of the irregularities 2a on the outer peripheral surface thereof.

Next, to explain its operation, first, the filling mold 1 is lowered and the elastic model 2 is inserted and set into the filling mold 1 as shown in the fourth figure, and then an air source or other device is connected to the fluid passage 5 inside the core bar 4. Fluid pressure source (not shown)
A fluid such as air is injected into the elastic model 2 through the through hole 6 on the outer surface of the elastic model 2, and the core bar 4 is inserted into the elastic model 2 while it is expanded under pressure as shown in FIG. 5a. After that, the pressurization by the fluid is released and the elastic model 2 is brought into close contact with the core metal 4 due to its elasticity, and the core metal 4 is fitted into the elastic model 2 without any gap, and then as shown in FIG. 5b. In this method, the mold material is filled into the gap between the filling port 1a of the filling mold 1 and the filling mold 1 around the elastic model 2 and hardened. A mold 7 that maintains the regular product shape and has high dimensional accuracy is obtained.

In addition, in the process of inserting the core metal 4 into the elastic model 2, since the model 2 is not restrained from the outer periphery by the mold 7, the core metal 4 can be press-fitted into the model 2 and fitted therein. This tends to cause distortion in the direction in which the core bar 4 is press-fitted into the model 2, and it is advantageous to insert the core bar 4 by expanding the model 2 under pressure with fluid pressure as described above, since no distortion will occur. . Further, the mold material can be cured by a conventional method such as a thermosetting method, a CO ₂ gas curing method, or a room temperature curing method. Next, air is forced into the elastic model 2 through the through hole 6 of the core metal 4, and the core metal 4 is pulled out from the elastic model 2, but in this case, the elastic model 2 is pressurized from inside by the air. A slight gap is formed between the inner circumferential surface and the core metal 4, and thus the core metal 4 is connected to the elastic model 2.
As a result, the elastic model 2 is restored to its original shape, which is smaller than the regular product shape by at least the height of the irregularities 2a on its outer surface, and the irregularities 2a are as shown in FIG. 5c. The elastic model 2 is released from the unevenness on the inner surface of the mold 7 as shown in FIG.

In the above embodiment, the elastic model 2 is formed in the shape of a bag with its upper end closed, but it is not limited to this. For example, as shown in FIG. It may be made to abut against an annular groove 8 formed on the lower surface of the upper wall of the mold 1 for sealing. In this case, the groove 8 is formed wide to allow the opening edge 2d to move outward when the elastic model 2 is expanded under pressure.
so that it can be inserted accurately.

Further, in the above embodiment, the elastic model 2 is formed into a shape that is more contracted than the regular product shape, and its restoring force is used to release the mold from the mold 7. However, when releasing the mold, negative pressure is applied inside the elastic model 2. This may be contracted and deformed by moving it, and an embodiment shown in FIGS. 7 and 8 is shown.

In this case, the elastic model 2 can be formed into a shape that substantially matches the regular product shape, and a fluid pressure source and a negative pressure source can be selectively connected to the fluid passage 5 of the core metal 4. Then, as shown in FIG. 8a, the core metal 4 is inserted into the elastic model 2 in a state in which the elastic model 2 is pressurized and expanded by fluid pressure, and then the pressure by the fluid pressure is released and the elastic model 2 is expanded. The core bar 4 is fitted to the
In this case, the fluid passage 5 is connected to a negative pressure source and both 2,
The degree of adhesion in step 4 may be increased.

In this state, as shown in FIG. 8b, after filling the periphery of the elastic model 2 with mold material and hardening it, the elastic model 2 is pressurized from inside with fluid pressure, and the core metal 4 is The above operation is not particularly different from that of the above embodiment, but in this embodiment,
Next, the fluid passage 5 is connected to a negative pressure source to create a negative pressure inside the elastic model 2. At this time, the elastic model 2 is attracted by the negative pressure and is contracted and deformed as shown in FIG. The mold can be reliably released from 7. However, if left as is, the elastic model 2 may be excessively contracted due to reasons such as excessive negative pressure, and its durability may be impaired.
The core metal 4 is formed into a cylindrical shape, and the elastic model 2 is attached to the inner circumference of the core metal 4.
An auxiliary core bar 9 is provided to be inserted into the auxiliary core bar 9.
This makes it possible to prevent excessive contraction of the elastic model 2.

Then, an internal fluid passage 5 and an outer surface through hole 6 are formed in the auxiliary core bar 9 in the same manner as the core bar 4 of the above embodiment, and the fluid passage 5 is switched between a fluid pressure source and a negative pressure source. The auxiliary core bar 9 is fixed to the lower machine frame 10 of the fixed frame 3 to which the elastic model 2 is attached, and the auxiliary core bar 9 is connected by the cylinder 11 on the lower side.
The cylindrical core metal 4 on the outer periphery of the core metal 4 was moved up and down to be inserted into and removed from the elastic model 2. The core metal 4 has
A through hole 6' is formed for applying fluid pressure to the inner surface of the elastic model 2 from the through hole 6 of the auxiliary core bar 9 when the elastic model 2 is pulled out.

Next, to explain its operation, first the auxiliary core bar 9
Fluid is pressurized into the elastic model 2 through the through hole 6, and the core metal 4 is inserted into the elastic model 2 in a state where it is expanded under pressure as shown in FIG. 10a, and then pressurized by fluid pressure. With the core metal 4 fitted into the elastic model 2, a mold material is filled around the elastic model 2 and hardened as shown in FIG. 10b. Next, the core bar 4 is pulled out while the elastic model 2 is pressurized from inside by introducing fluid pressure through the auxiliary core bar 9, and then the fluid passage 5 is connected to a negative pressure source and the elastic model 2 is pressurized from inside. The elastic model 2 is contracted and deformed to be released from the mold 7.
In this case, the elastic model 2 comes into contact with the auxiliary core metal 9 as shown in FIG. 10c, and is prevented from shrinking excessively.

As described above, when using the method of the present invention, the elastic model is held in the regular product shape by the core metal fitted into it, and the mold material is filled around the elastic model and hardened, unlike the conventional method. The dimensional accuracy of the mold can be dramatically improved compared to the method of filling an elastic model with fluid to maintain its shape. When the core metal is pulled out, the elastic model is compressed by fluid pressure from inside, and a gap is formed between the elastic model and the core metal, so the core metal can be pulled out smoothly. There is no adverse effect on the elastic model or the mold, and furthermore, according to the device of the second invention, since the core bar is configured to have an internal fluid passage and a through hole on the outer surface connected to the inner fluid passage, there is no adverse effect on the elastic model or the mold. There is no need for a separate introduction device such as an air nozzle for introducing fluid pressure into the mold, which simplifies the structure.Furthermore, according to the device of the third invention, the elastic model and its interior are contracted and deformed by the action of negative pressure. When releasing the mold from the mold, even if the negative pressure is strengthened to increase the mold release force, the auxiliary core prevents the elastic model from shrinking excessively, thereby improving the durability of the elastic model.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view of one example of a cast product, Fig. 2 is a plan view thereof, Figs.
The figure is a cut-away side view of an example of the apparatus used to carry out the method of the present invention, FIGS. 5 a, b, and c are cut-away side views illustrating its operation, and FIG. , FIG. 7 is a cutaway side view of another embodiment, FIGS. 8a, b, and c are cutaway side views explaining its operation, FIG. 9 is a cutaway side view of still another embodiment, and FIG. 10a is a cutout side view of another embodiment. , b, and c are cutaway side views illustrating its operation. 1...Filled mold, 2...Elastic model, 2a...Irregularities, 4...
Core metal, 7...Mold, 9...Auxiliary core metal.

Claims (1)

[Claims] 1. A mold for casting a product having irregularities on the outer peripheral surface,
In a method for manufacturing a mold using a hollow elastic model having irregularities on the outer peripheral surface corresponding to the shape of the product, a core metal is provided which fits into the elastic model to maintain the regular product shape; With the cored metal fitted into the elastic model, a mold material is filled around the elastic model and hardened, and then the cored metal is filled with the elastic model and pressurized from inside with fluid pressure. A method for manufacturing a mold, characterized in that after the elastic model is pulled out from the elastic model, the elastic model is contracted and deformed to be released from the mold. 2 The elastic model is formed into a shape that is shrunk from the regular product shape by at least the height of the irregularities on its outer peripheral surface, and when the core metal is pulled out of the elastic model, the elastic model is contracted and deformed by its elasticity and released from the mold. 2. The method of manufacturing a mold according to claim 1, wherein the mold is released. 3. Claim 1, characterized in that, after the core metal is pulled out from the elastic model, the elastic model is contracted and deformed by the action of negative pressure inside the elastic model to be released from the mold. Method of manufacturing the mold described. 4. After the core metal is inserted into the elastic model in a state in which it is expanded under pressure using fluid pressure, the pressure is released by fluid pressure and the core metal is fitted into the elastic model. A method for manufacturing a mold according to any one of claims 1 to 3, characterized in that: 5. A hollow elastic model for producing a casting mold for a product having an uneven outer circumferential surface with an uneven outer surface corresponding to the shape of the product, and a filling mold for mold material that accommodates the elastic model in a manner that allows the elastic model to be freely inserted and removed. In the device, a core metal that fits into the elastic model and holds it in a regular product shape is provided so as to be able to be freely inserted into and removed from the elastic model, and the core metal has an internal fluid passage and an outer surface that passes through the fluid passage. 1. An apparatus for manufacturing a mold, characterized in that a through hole is formed so that a fluid pressure source can be freely connected to the fluid passage. 6. The mold manufacturing apparatus according to claim 5, wherein the fluid pressure source and the negative pressure source can be selectively connected to the fluid passage. 7. A method for manufacturing a casting mold for a product having an uneven outer surface, comprising: a hollow elastic model having an outer surface unevenness corresponding to the shape of the product; and a filling mold for mold material that accommodates the elastic model in a freely retractable manner; , a device comprising a core metal that fits into the elastic model and holds it in a regular product shape, which can be freely inserted into and removed from the elastic model, the core metal being formed into a cylindrical shape, An auxiliary core bar inserted into the elastic model is provided, an internal fluid passage and a through hole on the outer surface connected to the fluid passage are formed in the auxiliary core bar, and the fluid passage is connected to a fluid pressure source and a negative A mold manufacturing device characterized by being able to be freely switched and connected to a pressure source.