JPH08215821A - Die casting method - Google Patents

Abstract

PURPOSE: To use a casting device having small size at a low cost and to obtain a die casting product excellent in the quality by using powdery releasing agent having a specific content of organic compound and specifying the die temp. at a cavity surface and the injection pressure of molten metal. CONSTITUTION: The powdery releasing agent having <=50% content of the organic compound is sprayed on a cavity 3 through a sleeve 4 with spouting gas 12. The molten metal in the sleeve 4 is injected into the cavity 3 by advancing a plunger tip 5. At this time, as necessary, the dies 1, 2 are locally cooled so that the surface temp. of the dies becomes <=270 deg.C. Further, the injection pressure is made to be <=20MPa. By this method, the die casting product excellent in the quality can be cast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting method used for aluminum or an aluminum alloy, and more particularly to a reduced pressure die casting method using a powder release agent.

[0002]

2. Description of the Related Art As a releasing agent used in die casting, a water-soluble releasing agent has been conventionally used in which mineral oil, fats and oils, wax, synthetic oil and the like are emulsified in water using a surfactant. However, in recent years, boron nitride, mica, metal oxides,
Techniques have been developed for using a powder release agent composed of an inorganic solid lubricant such as silicon nitride and an organic compound such as metallic soap or a polymer compound. For example, Japanese Examined Patent Publication No. 6-9730 discloses various powder mold releasing agents for die casting, and the Japanese Die Casting Conference Proceedings JD92-03p.
In p23-26, the weight% of the polymer compound is 5, 10
20 and 50% powder release agents are disclosed. Regarding the die surface temperature in die casting using a powder release agent, see JD92-05pp37-4 mentioned above.
No. 1 discloses that it is preferable not to exceed 200 ° C. Further, the above-mentioned collection of papers JD94-33pp283-29
2 uses a powder mold release agent, injection pressure 17.5MPa
It is disclosed to cast in.

[0003]

However, in the above-mentioned conventional techniques, the content of the polymer compound in the powder mold release agent, the mold temperature on the cavity surface, and the injection pressure of the molten metal are individually determined. It only teaches casting conditions, and overall there is no teaching as to how best to set these conditions. Therefore, an object of the present invention is to provide a casting method capable of obtaining a good cast product in the reduced pressure die casting method.

[0004]

The present invention has been made to achieve the above object, that is, a cavity is formed by a fixed mold and a movable mold, the cavity is decompressed, and a cavity is formed. In the die-casting casting method in which a powder mold releasing agent composed of an inorganic solid lubricant and an organic compound is supplied to the mold surface of the tee and applied to the mold surface, and a molten metal is further injected into the cavity to solidify the powder. Die casting, wherein the content of the organic compound in the body release agent is 50% or less, the mold temperature on the surface of the cavity is 270 ° C. or less, and the injection pressure of the molten metal is 20 MPa or less. It is a casting method.

[0005]

The reason for limiting each manufacturing condition of the present invention is as follows. The powder release agent is an inorganic solid lubricant such as boron nitride, mica, metal oxide, silicon nitride, and metal soap (sodium, calcium, barium, lithium, potassium, magnesium, or zinc in carboxylic acid skeleton), polymer It is a mixture with an organic compound composed of a compound (polyethylene, polypropylene, epoxy resin, alkyd resin, or polystyrene). This mixing ratio is such that the content ratio of the organic compound is 50% or less. This is because after the powder mold release agent is applied to the surface of the mold, the organic compound reacts with the heat of the molten metal when it comes into contact with the molten metal such as aluminum, burns out, gasifies, and mixes into the molten metal. This is because it becomes a blow hole. Further, if the powder release agent does not contain an organic compound, the inorganic solid lubricant cannot be attached to the surface of the mold, so it is necessary to contain 0.1% or more. Inorganic solid lubricants other than the above-mentioned organic compounds do not react even when they come into contact with the molten metal, are present on the surface of the mold, reduce the thermal conductivity between the molten metal and the mold, and act as a heat insulating agent. Prevents the decrease in hot water temperature. Therefore, since the temperature of the molten metal in the cavity is maintained at a high temperature, the molten metal can spread to a thinner portion as compared with the conventional one, so that a thinner product can be obtained as compared with the conventional die casting method.

[0006] Also, the fact that the temperature of the hot water does not drop is small
Since injection can be performed at a lower temperature than before, the mold material used can be a low-grade material, and the usable time is extended when a conventional high-grade material is used for the mold. Further, the mold surface temperature is set to 270 ° C. or lower because the organic compound in the powder release agent melts. Also, the injection pressure can be 20 MPa or less because the flow of molten metal is improved by using the powder mold release agent as described above, so the injection pressure of the casting machine itself is lower than that of the conventional one, and the casting machine itself is also small. Can be realized.

[0007]

The present invention will be described with reference to the drawings. FIG. 1 shows an example of a casting apparatus for applying the method of the present invention. This casting apparatus has a fixed mold 1 and a movable mold 2, and both molds 1,
The cavity 3 is formed by 2. A sleeve 4 is connected to the fixed mold 1, and a plunger tip 5 that slides by a pressing device (not shown) is installed inside the sleeve 4. An electromagnetic pump 6 for supplying molten aluminum alloy is connected to the lower surface of the sleeve 4, and an electrostatic nozzle 7 is attached to the upper surface of the sleeve 4. The tank 8 is filled with the powder release agent 9, and the powder release agent 9 in the tank 8 is fluidized by the flowing air 10. As the powder release agent 9, talc,
Boron nitride, mica, graphite inorganic solid lubricant 80 to 90% and polymer compound 10 to 20%.

A constant flow rate discharge device 11 is connected to the tank 8. By discharging discharge air 12 to the constant flow rate discharge device 11, the powder release agent 9 is transferred from the electrostatic nozzle 7 through the sleeve 4 to the cavity. It is configured to discharge to the tee 3. The electrostatic nozzle 7 is connected to the negative electrode of the high voltage generator 13, the positive electrode of the high voltage generator 13 is connected to the fixed mold 1, and the powder release agent discharged from the electrostatic nozzle 7 in this manner. 9 is applied to the surface of the cavity 3 by an electrostatic coating method. The cavity 3 is a vacuum shutoff valve 1.
4 is connected to a vacuum tank 15 whose pressure is reduced by a vacuum pump 16.

Next, a die casting method using the above casting apparatus will be described. First, the movable die 2 is moved forward to be closely attached to the fixed die 1 to form a cavity 3, and then the plunger tip 5 is attached. By slightly advancing, the hot water supply port from the electromagnetic pump 6 is closed as shown in FIG. 1, the vacuum shutoff valve 14 is opened, and the inside of the cavity 3 is vacuumed by the vacuum tank 15. After the degree of vacuum in the cavity 3 has increased to a certain degree, the vacuum shutoff valve 14 is closed and the constant flow rate dispenser 1
1 is operated to discharge the powder release agent 9 through the sleeve 4 into the cavity 3 by the discharge gas 12. As a result, the powder release agent is applied to the inner surface of the sleeve 4 and the die surface of the cavity 3. Next, the plunger tip 5 is retracted, the molten aluminum alloy is poured into the sleeve 4 by the electromagnetic pump 6, and the plunger tip 5 is advanced to inject the molten metal in the sleeve 4 into the cavity 3.
At this time, the dies 1 and 2 are locally cooled, if necessary, so that the surface temperature of the dies becomes 270 ° C. or lower. The injection pressure is 20 MPa or less. After the molten aluminum alloy poured into the cavity 3 is solidified, the movable mold 2 is retracted to take out the cast product, and one casting cycle is completed.

As described above, in this embodiment, since the powder mold releasing agent having the content of the polymer compound of 50% or less is used,
Over 50% of the inorganic solid lubricant adheres to the surface of the cavity 3 without burning, and this acts as a heat insulating material to prevent the decrease of the hot water temperature. Therefore, since a lower temperature molten metal can be poured, a high temperature resistant material becomes unnecessary, and the number of shots in the same mold 1 and 2 can be increased. Further, since the mold temperature on the surface of the cavity is 270 ° C. or lower, the mold life is extended and the defects of the metal structure are reduced. Furthermore, since the injection pressure of the molten metal is 20 MPa or less, the casting apparatus can be downsized.

[0011]

As described above, in the method of the present invention, a powder mold releasing agent having an organic compound content of 50% or less is used, the mold temperature on the surface of the cavity is 270 ° C. or less, and the molten metal is melted. Since the injection pressure of is set to 20 MPa or less, it is possible to cast a die-cast product of excellent quality using a small-sized and inexpensive casting device.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a casting apparatus to which the method of the present invention is applied.

[Explanation of symbols]

1 ... Fixed mold 2 ... Movable mold 3
… Cavity 4… Sleeve 5… Plunger tip 6
… Electromagnetic pump 7… Electrostatic nozzle 8… Tank 9
… Powder release agent 10… Flowing air 11… Constant flow rate dispenser 1
2 ... Discharge air 13 ... High voltage generator 14 ... Vacuum shutoff valve 1
5 ... Vacuum tank 16 ... Vacuum pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Iizuka 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nititsu Metal Co., Ltd.

Claims (1)

[Claims] 1. A powder mold release agent comprising a fixed mold and a movable mold to form a cavity, the pressure of the cavity is reduced, and an inorganic solid lubricant and an organic compound are formed on the mold surface of the cavity. In the die casting method of injecting a molten metal into the cavity and solidifying the molten metal by injecting the molten metal into the cavity, the content of the organic compound in the powder release agent is 50% or less, A die casting method, wherein the mold temperature on the surface of the tee is 270 ° C. or lower, and the injection pressure of the molten metal is 20 MPa or lower.