JPH0154151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to molding methods such as low pressure casting, die casting, and molten metal casting, and particularly to a molding method suitable for high-temperature molten metal.

<Prior art and its problems> Generally, when a high-temperature molten metal, that is, a molten metal with a melting point of about 700 to 1,600°C, is used, a larger amount of gas is generated during solidification than a metal with a lower melting point.

However, the degassing means in conventional molding methods, for example, the degassing means disclosed in Japanese Patent Application Laid-open No. 58-47538, does not allow communication between the inside of the cavity (molding part) of the mold (molding mold) and the outside of the mold. gas vent part,
Alternatively, one mold (fixed side insert 6) is entirely formed of a porous material such as ceramic material, and the structure is such that gas in the cavity is expelled outside the mold through this porous material. Entrained gas (outside air) that enters the cavity when closing a mold or pouring molten metal into the cavity can be efficiently removed, but gas generated during the solidification process of the molten metal cannot be removed efficiently. As a result, the gas generated during the solidification process of the molten metal caused shrinkage cavities and gas cavities.

In other words, the molten metal injected into the cavity solidifies from the outer periphery in contact with the cavity surface, and at the same time as the solidification occurs, a coagulated film is formed on the outer periphery, and then the flow (air permeability) with the outside is interrupted. This is because it is blocked by the coagulated film.

In addition, as disclosed in Japanese Patent Publication No. 51-45532, the entire mold is made of a porous material so that the entire mold has a breathable structure that communicates from the inside of the cavity to the outside of the mold. There is a molding method in which the gas is forcibly sucked out using a vacuum pump, but this molding method also causes a solidified film to form on the outer periphery of the molten metal in contact with the cavity surface, similar to the former molding method described above. After the coagulation process, the flow to the outside is blocked by the coagulation film, and the problem remains that the gas generated during the coagulation process cannot be efficiently removed.

<Problems to be Solved by the Invention> The technical problems to be solved by the present invention include not only eliminating the entrained gas (outside air) that entered during mold clamping and pouring the molten metal, but also eliminating the molten metal, especially the one with a melting point of about 700 to 1600℃. To provide a forming method that can effectively and reliably eliminate a large amount of gas generated during the solidification process of molten metal until the end of the casting process.

<Means for Achieving the Technical Problem> The technical means taken by the present invention to achieve the above-mentioned problem is to use a mold that faces the inside of the molding part of a mold that is equipped with a heating mechanism and a cooling mechanism that control the temperature inside the molding part. Incorporating porous ceramic into the mold component of the mold, forming a gas vent passage leading from the inside of the molding part to the outside of the mold, and forming a gas vent passage near the inner end part facing into the molding part of the gas vent passage. A heating mechanism is installed to melt the solidified film of the molten metal.
An injection step of injecting high-temperature molten metal into the molding section, a pressurizing step of pressurizing the injected high-temperature molten metal, and a temperature at which the heating mechanism and cooling mechanism are operated to heat and maintain the pressurized high-temperature molten metal in a semi-solidified state. heating and cooling steps for controlling the inside of the forming part in a temperature range in which the pressurized high-temperature molten metal solidifies, and in which the solidification progresses to grow toward the inner end portion of the gas vent passage; , an intake process for forcibly drawing air into the gas vent passage;
After the pressurizing step is completed, the heating mechanism disposed near the inner end of the gas vent passage is activated to heat the inner end of the gas vent passage.

<Function> According to the technical means of the present invention described above, after the mold is clamped, high-temperature molten metal is injected into the molding part, and when the molten metal is pressurized, the gas vent passage is opened. A heating mechanism disposed near the inner end portion facing into the molded portion is activated to actively heat the inner end portion of the gas vent passage. As a result, the high-temperature molten metal is injected into the molding part, and as the outer peripheral part of the high-temperature molten metal in contact with the molding part surface (cavity surface) solidifies, which starts almost simultaneously with the end of the injection (filling), a formation occurs at the inner end of the gas vent passage. The solidified film is melted to the same semi-solidified state as the molten metal near the center of the molding part, where solidification is delayed compared to the outer peripheral part, thereby ensuring a flow condition in the inner end part of the gas vent passage to the outside of the mold. ,
In the heating and cooling process, the heating mechanism and cooling mechanism control the temperature inside the forming section to a temperature range that maintains the high-temperature molten metal in a semi-solidified state, and then control the temperature inside the forming section to a temperature range that solidifies the high-temperature molten metal. The generated gas (internal gas) generated during the solidification process of the molten metal is pushed toward the inner end portion of the gas vent passage that communicates with the outside by the pressure inside the molding part due to the pressurization process, and is forced into the gas vent passage. It is sucked out to the outside by the intake air.

<Example> An example of the present invention will be described based on the drawings.
The mold A consists of a set of an upper mold a ₁ and a lower mold a ₂ , 1 is a molding part, 2 is an injection port, 3 and 4 are pressure pins, and 5 is a part of the mold component of the mold A. This is the core.

The upper mold a ₁ is made of a heat-resistant metal (including sintered metal) such as high chromium molybdenum steel, and a heating mechanism 6 and a cooling mechanism 6' are appropriately disposed within this mold a ₁ .

The lower mold _a2 is a Si ₃ N ₄ ceramic mold, and a heating mechanism 7 and a cooling mechanism 7' are provided in the mold.

The core 5 is made of heat-resistant metal (including sintered metal) such as high chromium molybdenum steel or Si ₃ N ₄ ceramic, and ZrO ₂ porous ceramic 8' is inserted and inserted from both axial end faces of the core 5. The inner end of the porous ceramic 8' faces the inside of the forming portion 1, and a gas venting passage 8 is formed by the porous ceramic 8'.

Incidentally, the porosity of porous ceramic 8' is, for example,
When using an Al-based alloy or a Cu-based alloy as a molten metal, the so-called molten metal m is preferably about 17%.

A heating mechanism 9 is disposed at the inner end of the core 5 near the inner end portion of the gas vent passage 8 facing into the molded part 1, and a vacuum mechanism 10 is connected to the outer end of the gas vent passage 8. , the molded part 1 via the gas vent passage 8
Forcefully inhale inside.

The melting point of the molten metal m injected from the injection port 2 is 700~
Uses high temperature molten metal of 1600℃.

In the above mold A, only the lower mold a ₂ is made of ceramic material, but the upper mold a ₁ may also be made of ceramic material, and the gas vent passage 8 using porous ceramic 8' is made of an inlet instead of a core. It is also optional to form it into a core or a set core.

Next, the casting process of this molding method using mold A configured as above will be explained.

Molten Metal Injection Step After the mold A has been clamped, high-temperature molten metal m is injected into the molding part 1 through the injection port 2 (see Fig. 1).

This molten metal injection may be either low-pressure injection or high-pressure injection.

Pressure process Pressure pins 3, 3' are pushed a predetermined distance toward the molding part 1, and the injected molten metal m in the molding part 1 is
to increase the pressure inside the molding section 1 (Fig. 2).

Heating and Cooling Step After the above pressurizing step is completed, the heating mechanism 9 is activated to actively heat the inner end portion of the gas venting passage 8 (the inner end surface portion of the core 5) facing into the molded part 1, The high-temperature molten metal m is injected into the molding section 1, and the high-temperature molten metal m starts almost at the same time as the injection (filling) ends.
As the outer peripheral portion solidifies, that is, the high-temperature molten metal in contact with the molded part 1 surface has a faster solidification growth than other portions, the inner end portion of the degassing passage 8 (including the inner end surface portion of the core 5) solidifies. ) is melted to the same semi-solidified state as the molten metal near the center of the molding part 1 where solidification is delayed (see Figure 2) to prevent the solidified film from blocking the flow to the outside (outside the mold). Then, the molded part 1 is heated and maintained in such a manner that the state of communication between the inside of the molded part 1 and the outside through the gas vent passage 8 is ensured until the end of the casting process (see FIG. 3).

The flow state of the inner end portion of the gas vent passage 8 by this heating climate 9 is ensured by mold temperature control using well-known thermocouples, etc. inserted into the core 5 and both upper and lower molds a ₁ and a ₂ near the inner end portion. The device (not shown) and the heating mechanism 9 are electrically connected, thereby controlling the temperature of the inner end portion of the gas vent passage 8 so that a solidified film is not formed at the inner end portion until the end of the casting process. This is to manage and control the mold temperature).

On the other hand, the heating mechanisms 6 and 7 are operated after the pressurizing process is completed, that is, at the same time as the heating mechanism 9 starts operating, or simultaneously with the pressurizing process, so that the high temperature molten metal m changes from a liquid layer to a solid layer in the forming section 1. After that, the cooling mechanisms 6' and 7' are operated to control and lower the temperature inside the forming part 1 to a temperature range where the high temperature molten metal m starts to solidify.

In this heating and cooling process, the high-temperature molten metal m in the forming part 1 is actively heated by the heating mechanism 9, and solidification progresses gradually toward the inner end of the gas vent passage 8 where communication with the outside is ensured. The heating mechanisms 6 and 7 control the temperature inside the molding section 1 to
The heating mechanisms 6, 7 and the cooling mechanism control the temperature so that the semi-solidified high temperature molten metal m in contact with the inner end portion of the gas vent passage 8 is solidified at the end of the casting process. 6' and 7' (see Figure 3).

Intake process Before the injection process, that is, from the start of the mold clamping operation to the end of the mold clamping operation, the vacuum mechanism 1
0 is activated to forcefully draw air into the gas vent passage 8 made of porous ceramic 8' to remove the entrained gas (outside air) that has entered the molding part 1 during the clamping of the mold A and the injection process. The suction is forcibly removed and the injection process is temporarily stopped almost at the same time as the end of the injection process.

Then, before the heating mechanism 9 starts operating in the heating and cooling process, or at a timing when the heating mechanism 9 melts the coagulated film at the inner end portion of the gas venting path 8, the vacuum mechanism 10 is operated again to make the gas venting path 8. This occurs during the solidification process of the high-temperature molten metal m, which grows and progresses as the temperature in the forming section 1 is moderately lowered by the cooling mechanisms 6' and 7' in the heating and cooling process, and the forming process in the pressurizing process. Due to the pressure inside part 1, gas vent passage 8
The generated gas that has been pushed toward the inner end of the cylinder is forcibly removed by the suction device.

The operation timing of the vacuum mechanism 10, which is activated after the solidified film at the inner end of the gas vent passage 8 is melted by the heating mechanism 9, is controlled by the thermocouple or the like inserted in the vicinity of the inner end of the gas vent passage 8. The mold temperature of the inner end portion is controlled by a temperature control device, that is, the time when the mold temperature of the inner end portion rises to a temperature range where the solidified film is melted by the heating mechanism 9 is automatically controlled. , which operates the vacuum mechanism 10.

At the end of the intake stroke, the heating mechanism 9 is stopped, and after a predetermined period of time, the cooling mechanism 6',
7' is stopped, the mold A is opened, and the molded product M is taken out.

<Effects of the Invention> As described above, the present invention includes a heating mechanism in the vicinity of the inner end portion facing the inside of the molding part of the gas vent passage leading to the outside of the mold, which is made of porous ceramic and is incorporated into the molding part of the molding mold so as to face each other. This heating mechanism is operated after the pressurizing process is completed during the casting process to heat the inner end of the gas vent passage, melting the solidified film formed on the inner end and melting it into the molded part. Since the solidified film on the inner end of the facing gas vent passage prevents the communication with the outside of the mold from being blocked, the gas vent passage remains closed until the end of the casting process, including the injection process, pressurization process, heating, cooling process, and suction process. It is possible to reliably ensure circulation (air permeability) between the inside of the molding part and the outside of the mold through the molding part. Therefore, entrained gas (outside air) that enters the molding part when the mold is clamped or when high-temperature molten metal is injected into the molding part.
Of course, it is possible to reliably and effectively eliminate the generated gas (internal gas) that is generated during the solidification process of high-temperature molten metal, and the amount of residual gas is significantly reduced compared to conventional methods, resulting in a high-temperature solution without voids. Capable of casting quality products.

Thus, we were able to achieve our intended purpose.

[Brief explanation of drawings]

The drawings are longitudinal cross-sectional views showing the casting process of the high-temperature molten metal forming method of the present invention. Figure 1 shows the state in which the high-temperature molten metal is injected into the molding section, and Figure 2 shows the state in which the high-temperature molten metal is pressurized and degassed. Figure 3 shows a state in which the solidified film at the inner end of the passage is melted, and Figure 4 shows a state in which the solidification of the high-temperature molten metal is growing sequentially toward the inner end of the gas vent passage. This shows the state in which a product has been obtained after the solidification of high-temperature molten metal has been completed. In the figure, A is the mold, 1 is the molding part, 2 is the injection port,
3 and 4 are pressure pins, 5 is a core, 6, 7, and 9 are heating mechanisms, 6' and 7' are cooling mechanisms, 8 is a gas vent passage,
8' is porous ceramic, and m is molten metal.

Claims (1)

[Claims] 1. Incorporating porous ceramic into a mold component of a mold, facing the inside of the molding part of the mold, which is equipped with a heating mechanism and a cooling mechanism for controlling the temperature inside the molding part, and forming a gas vent path leading from the inside of the molding part to the outside of the mold. At the same time, a heating mechanism for melting a solidified film of molten metal formed on the inner end portion is disposed near the inner end portion of the gas vent passage facing into the molding portion, and high temperature molten metal is injected into the molding portion. injection step, a pressurizing step of pressurizing the injected high-temperature molten metal, and controlling and pressurizing the inside of the molding part to a temperature range that maintains the pressurized high-temperature molten metal in a semi-solidified state by operating the heating mechanism and cooling mechanism. heating and cooling steps for controlling the inside of the forming part to a temperature range in which the high-temperature molten metal solidifies and in which the solidification progresses toward the inner end portion of the gas vent path; Intake step of drawing air Among these casting steps, after the pressurization step is completed, the heating mechanism disposed near the inner end of the gas vent passage is activated to heat the inner end of the gas vent passage. A high-temperature molten metal forming method characterized by: