JPH06328190A - Powder parting material for casting - Google Patents

Abstract

PURPOSE:To adjust the deposition of a releasing agent according to temp. distribution of metallic molds and to adjust the kind of the releasing agent by mixing plural resin powders varying in m.p. and inorg. powders. CONSTITUTION:The powder releasing agent for casting is formed by mixing at least two kinds of the resin powders varying in m.p. and at least one kind of the inorg. powder. This releasing agent is applied on the metallic molds. The temp. rises in the metallic mold parts existing near sprues and the metallic mold parts corresponding to the thick parts of castings and, therefore, all the low-, middleand high-melting resin powders melt and becomes to a tacky adhesive state after adhesion. Only the low melting resin powder or the low- and middle-melting resins melt and become to the tacky adhesive state in the parts A where the mold metal temp. is relatively low but the tacky adhesive power thereof is low. The many inorg. powder sticks to the high-temp. parts C but the inorg. powders sticking to the low-temp. parts A are hot large in amt. Then, the seizure in the high-temp. parts by casting is prevented and the remaining of the parting material in the low temp. parts does not arise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting powder release agent which is applied to a die in casting such as die casting and squeeze, and in particular, the casting powder whose adhering amount can be adjusted according to the temperature distribution of the die. Body release agent.

[0002]

2. Description of the Related Art Conventionally, in casting techniques such as die casting and squeeze, a mold release agent is applied to the inner surface of the mold to prevent direct contact between the mold and molten metal, prevent seizure, and separate the cast product from the mold. To be good. When a water-insoluble release agent is used as the release agent, the water-soluble release agent is often used because of the danger of smoking and ignition. However, in the case of a water-soluble mold release agent, there is a possibility that defects may occur inside the cast product due to the phenomenon of residual water, and the problem of water pollution after use arises.

In order to overcome such a problem, Japanese Patent Laid-Open No. 3-24
The invention described in Japanese Patent No. 3242 proposes a technique of applying a mold release agent composed of an organic compound and a powdery or granular organic compound containing no water to a mold.

[0004]

However, in the mold, the temperature near the sprue and the thick part of the cast product are high, and the temperature distribution is not uniform. In the invention described in the above publication, the temperature distribution of the mold is taken into consideration. Not having the following problems. First
It is difficult to attach a lot of release agent to the high temperature part of the mold where seizure easily occurs, and the possibility of seizure cannot be ruled out in the high temperature part. Secondly, the release agent is required much in the low temperature part. Since the release agent adheres to the non-existing portion, the release agent component is deposited and the quality of the product is deteriorated due to coloring or the like.

Therefore, the present invention is capable of overcoming the above-mentioned conventional problems and adjusting the amount of the release agent adhered and the type of the release agent according to the temperature distribution of the mold, resulting in seizure or seizure. It is an object of the present invention to provide a powdery mold release agent for casting that does not cause the problem of residual shrinkage cavities.

[0006]

In order to achieve the above object, the present invention provides a casting powder release agent comprising a mixture of at least two resin powders having different melting points and at least one inorganic powder. providing. The resin powder and the inorganic powder are simply mixed, or the respective resin powders are previously attached to the inorganic powder to form a mixture.

The present invention further comprises at least two kinds of resin powders having mutually different melting points and at least two kinds of inorganic powders, and the same kind of resin powders are adhered to the same kind of inorganic powders in advance to form a mixture. We provide powder release agents.

[0008]

According to the above casting powder release agent of the present invention, in the high temperature part of the mold, both the low melting point and the high melting point resin powders are melted and adhered to increase the adhesiveness of the mold surface. Also, the amount of the inorganic powder attached increases. Therefore, the releasability is improved and the seizure at high temperature can be prevented. On the other hand, since only the low melting point resin is melted and adhered in the low temperature part of the mold, the adhesiveness is weak and the amount of the inorganic powder adhered is small, so that the defect that the release agent remains does not occur.

Further, by relating the kind of the resin powder to the kind of the inorganic powder and adhering the resin powder to the inorganic powder in advance, a release agent required according to a desired portion of the mold. It is possible to selectively exert the performance of.

[0010]

EXAMPLE A casting powder release agent according to an example of the present invention will be described. Paraffin as a material for resin powder,
Polycarbonate, polyethylene, nylon, etc. are used. Their melting points are 46 ° C, 220 ° C, 13 respectively.
The temperature is 7 ° C. and 260 ° C., and different resin powders are used depending on the mold temperature. The inorganic powder is scale-like, and mica, talc, molybdenum disulfide, graphite, aluminum powder, diatomaceous earth, etc. are used.

The resin powder and the inorganic powder are mixed with each other and then applied to a mold. Since the temperature of the mold part near the sprue and the mold part corresponding to the thick part of the cast product becomes high, after the resin powders of low melting point, medium melting point and high melting point are adhered, they are all melted to be in an adhesive state. On the other hand, in the part where the mold temperature is relatively low, only the low-melting point resin powder or only the low-melting point resin powder and the medium-melting point resin powder are melted into an adhesive state. Weaker than power. This is because even the high melting point resin powder is not melted and adhered. Therefore, a large amount of the inorganic powder adheres to the high temperature portion, but a large amount of the inorganic powder does not adhere to the low temperature portion. Therefore, seizure in the high temperature portion due to casting can be prevented, and the release agent does not remain in the low temperature portion. Alternatively, the resin powder may be adhered to the inorganic powder in advance, and they may be mixed and applied to the mold.

Further, if necessary, one of the resin powders is attached to one of the inorganic powders to form a powder. For example, by attaching nylon powder to aluminum powder,
Powder is formed and polyethylene powder is attached to diatomaceous earth to form a second powder. These first powder and second
By mixing and using the above powders, the high thermal conductivity of aluminum powder and the high heat insulating property of diatomaceous earth can be utilized depending on the temperature distribution of the mold due to the difference in melting point between nylon and polyethylene.

Next, a specific example of this embodiment will be described. Specific Example 1 As the product A of the present invention, a resin powder was prepared in which paraffin powder (melting point 46 ° C.) and polycarbonate powder (melting point 220 ° C.) were mixed at a weight ratio of 1: 1. Then, talc (particle size 2 μm) was prepared as an inorganic powder. And these were mixed and the powder mold release agent was formed. Further, as Comparative Example 1, paraffin powder and talc, as Comparative Example 2, polycarbonate powder and talc, and as Comparative Example 3, polyethylene powder (melting point 13
A mixture of 7 ° C.) and talc was prepared.

The powder release agent mixed as described above is applied to a mold,
Next, the molten metal was supplied to the mold and casting was performed under the following conditions. 90 ton die casting machine, melt temperature 700 ° C, alloy ADC10 product The product shown in Fig. 1 was cast by a test mold.
(Product weight 0.6kg) Casting pressure 760Kg / cm ² Injection speed 1m / s

In the product of FIG. 1, the portion A is the portion farthest from the sprue, and the portion C is the portion closest to the sprue. Due to the directional solidification, the mold temperature is raised closer to the sprue, and coagulation starts from the farthest position from the sprue. Therefore, A
The part, the part B, and the part C are a low temperature part, a medium temperature part, and a high temperature part, respectively. When the powder mold release agent of the invention product A is applied to the mold,
Since paraffin has a low melting point, it melted and adhered to the entire surface of the mold in a tacky state. On the other hand, since the polycarbonate has a high melting point, it does not melt and adhere to the low temperature part, but melts and adheres in a sticky state in the high temperature part. Therefore, since the adhesive strength is weak in the low temperature part and strong in the high temperature part, talc adheres to the high temperature part to form a relatively thick release agent layer, while the low temperature part forms a thin release agent layer. Formed. On the other hand, in Comparative Example 1, the adhesion of talc in the high temperature portion was not sufficient, and there was a tendency that the adhesion of talc was excessive in the low temperature portion. In Comparative Example 2, the adhesion of talc in the low temperature part and the intermediate temperature part was not sufficient, and in Comparative Example 3, the adhesion of talc in the intermediate temperature part was good, but the adhesion of talc was not sufficient in the mold high temperature region. The experimental results are shown in Table 1.

(Table 1) Part A (low temperature) Part B (medium temperature) Part C (high temperature) Product A of the present invention A ○ Good ○ Good ○ Good Comparative Example 1 × Release agent deposition (large) △ Seizure (small) × Burn-in (Large) Comparative Example 2 × Scratch × Scratch ○ Good Comparative Example 3 △ Release Agent Accumulation (Small) ○ Good × Burn-in (Medium)

As is clear from Table 1, in the case of the product A of the present invention, no galling or mold release agent was deposited in the low temperature portion, and no seizure was generated in the intermediate temperature portion or the high temperature portion. On the other hand, in Comparative Example 1, since only low melting point paraffin was used as the resin powder, excessive talc adhered to the low temperature portion. Further, the reason why the seizure often appeared in the high temperature part was that talc did not sufficiently adhere to the part due to a decrease in viscosity of the molten paraffin. Further, in Comparative Example 2, since only the high melting point polycarbonate was used as the resin powder, the resin powder was insufficiently melted in the low temperature part and the intermediate temperature part, and talc did not adhere sufficiently to the part, causing galling. . On the other hand, in the high temperature part, the desired amount of talc could be attached due to the melting of the polycarbonate, and seizure did not occur. Further, in Comparative Example 3, since only polyethylene having a melting point between paraffin and polycarbonate was used as the resin powder, a predetermined amount of talc could be adhered in the middle temperature part, but talc adhesion due to melting was slightly too much in the low temperature part, At a high temperature part, a desired amount of talc could not be attached due to a decrease in viscosity, so that galling and seizure occurred.

Example 2 As the product B of the present invention, a resin powder prepared by mixing paraffin and polycarbonate in a weight ratio of 2: 8 was prepared. In addition, mica having a particle size of 2 μm was prepared as an inorganic powder. And this was mixed and the powder mold release agent was formed. Further, as the product C of the present invention, a resin powder prepared by mixing paraffin, polycarbonate and nylon in a weight ratio of 2: 5: 3 was prepared. Further, mica having a particle diameter of 2 μm was prepared as an inorganic powder, and a powder mold release agent was formed by mixing these. A water-soluble emulsion mold release agent was prepared as Comparative Example 4, paraffin and the above talc were prepared as Comparative Example 5, polycarbonate and the above talc were prepared as Comparative Example 6, and a mixture of nylon and the above talc was prepared as Comparative Example 7. The coating method was the same as in Example 1, the experimental conditions were as follows, and the experimental results are shown in Table 2. 800 ton die casting machine, molten metal temperature 680 ℃, alloy ADC10 product Clutch cover case (product weight 2.7kg) Casting pressure 600kg / cm ² Injection speed 40m / s

(Table 2) Thin portion (low temperature portion) Thick portion (high temperature portion) Other (medium temperature portion) (boss portion) Invention product B ○ Good △ Seizure (small) ○ Good Invention product C ○ Good ○ Good ○ Good Comparative example 4 × Poor bathing × Seizing (medium) △ Slightly defective running of comparative example 5 × Release agent deposition (large) × Seizing (large) △ Seizing (small) Comparative example 6 △ Gazing ( Small) △ Image sticking (small) ○ Good Comparative example 7 × Scratch (large) ○ Good △ Scratch (small)

As is clear from Table 2 above, in the products B and C of the present invention, since the low melting point paraffin melts even in the thin portion where the temperature is relatively low, the necessary amount of talc does not adhere to cause galling and the talc is high. Since the melting point of polycarbonate and nylon are also mixed, unnecessary adhesion of talc is prevented and the release agent is prevented from accumulating. Further, a desired amount of talc was adhered to the thick portion, which is a high temperature portion, due to melting of the high melting point material, and seizure did not occur.

Example 3 As the product D of the present invention, a first coating powder obtained by coating aluminum powder (particle size 1 μm) with nylon (melting point 260 ° C.) in a weight ratio of 4: 6 and diatomaceous earth with polyethylene (melting point 140 ° C.). A second coating powder was prepared by coating powder (particle size: 2 μm) at a weight ratio of 3: 7, and a powder mold release agent was prepared by mixing the first and second coating powders at a weight ratio of 4: 6. As Comparative Example 8, powder coated with talc with polycarbonate in a weight ratio of 1: 1 was prepared. The powder was attached to a mold and an experiment was conducted under the following conditions. The experimental results are shown in Table 3.

2200 ton die casting machine Melt temperature 680 ° C Alloy ADC10 product Housing body (weight 10kg) Casting pressure 700kg / cm ² Injection speed 50m / s

(Table 3) High temperature part (thickness part) Low temperature part Product D of the present invention D △ Shrinkage cavities (small) ○ Good bathing Comparative Example 8 × Shrinkage cavities (large) △ Hot bathing is slightly bad

A large amount of aluminum powder adheres to the high temperature portion, which improves heat transfer. Therefore, the cooling rate can be increased and the shrinkage cavities are reduced. Also, a large amount of diatomaceous earth powder, which has a large heat insulating property, adhered to the low temperature part, which improved the heat insulating property. Therefore, the temperature drop of the molten metal can be prevented and the hot running property is improved.

[0025]

EFFECTS OF THE INVENTION According to the mold release agent for a mold of the present invention described in detail above, the amount of the inorganic powder adhered can be controlled according to the temperature of the mold, causing seizure or residual release agent. You can prevent defects. That is, in the high temperature part of the mold, the resin powder having both a low melting point and a high melting point increases the adhesiveness of the surface of the mold, so that the amount of the inorganic powder adhered is large. Therefore, releasability is improved and seizure can be prevented. Further, since only the low-melting point resin adheres to the mold low temperature part, the adhesiveness is weak and the amount of the inorganic powder adhered is small, so that the release agent does not remain. Furthermore, since different types of inorganic powders can be dispersed according to the temperature of the mold, the performance of the mold releasing agent required by the part of the mold can be selectively and effectively exhibited.

[Brief description of drawings]

FIG. 1A is a plan view showing a cast product by a test mold, and FIG. 1B is a sectional view thereof.

[Explanation of symbols]

 A Low temperature part B Medium temperature part C High temperature part

Claims (3)

[Claims] 1. A powder release agent for casting, comprising a mixture of at least two kinds of resin powders having different melting points and at least one kind of inorganic powder. 2. The mold release agent for casting according to claim 1, wherein each of the resin powders adheres to the inorganic powder in advance. 3. At least two resin powders having different melting points and at least two inorganic powders,
A powder release agent for casting, characterized in that the same kind of resin powder adheres to the same kind of inorganic powder in advance to form a mixture.