JP2980790B2 - Powder release agent for casting - Google Patents

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 applied to a mold in casting of die casting, squeeze, etc., and more particularly to a casting powder capable of adjusting the amount of adhesion according to the temperature distribution of the mold. It relates to a mold release agent.

[0002]

2. Description of the Related Art Conventionally, in casting techniques such as die casting and squeezing, a mold release agent is applied to the inner surface of a mold to prevent direct contact between the mold and the molten metal, prevent seizure, and release the cast product from the mold. You are good. When a water-insoluble release agent is used as a release agent, there is a danger of smoking or ignition, and thus a water-soluble release agent is frequently used. However, in the case of the water-soluble release agent, there is a possibility that a defect occurs inside the cast product due to a water residue phenomenon, and there is a problem of water contamination after use.

In order to overcome such a problem, Japanese Patent Laid-Open Publication No.
The invention described in Japanese Patent No. 3242 proposes a technique in which a mold release agent comprising a powdery or granular organic compound and an inorganic compound without containing water is applied to a mold.

[0004]

However, in the mold, the temperature near the gate and the thick part of the cast product become 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 many release agents to the high temperature part of the mold where seizure is likely to occur, and the possibility of seizure cannot be denied in the high temperature part. The release agent adheres to the non-existing portions, so that the release agent component is deposited and the quality of the product is deteriorated due to coloring or the like.

Accordingly, the present invention can overcome the above-mentioned conventional problems and adjust the amount of the release agent and the type of the release agent according to the temperature distribution of the mold. It is an object of the present invention to provide a powder release agent for casting which does not cause a problem of generation of a sink mark remaining in the release agent.

[0006]

[0007]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
According to the present invention, there is provided at least two kinds of resin powders having different melting points and at least two kinds of inorganic powders, and the same kind of resin powder adheres to the same kind of inorganic powder in advance to form a powder mixture for casting. We provide mold agents.

[0008]

According to the above-mentioned powder releasing agent for casting of the present invention, in the high temperature portion of the mold, both the low melting point and the high melting point resin powders are melted and adhered, so that the adhesiveness of the mold surface becomes strong. In addition, the amount of the inorganic powder attached increases. Accordingly, the releasability is improved and seizure in a high-temperature portion can be prevented. On the other hand, only the low melting point resin is melted and adhered in the low temperature part of the mold, so that the adhesion is weak and the amount of the inorganic powder adhered is small, so that there is no disadvantage that the release agent remains.

In addition, the type of the resin powder is preliminarily adhered to the inorganic powder in association with the type of the inorganic powder, so that a release agent required according to a desired portion of the mold is provided. Can be selectively exerted.

[0010]

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

The resin powder and the inorganic powder are mixed with each other and then applied to a mold. Since the temperature is high in the mold portion near the gate and the mold portion corresponding to the thick part of the cast product, the resin powders having a low melting point, a medium melting point, and a high melting point are all melted and adhered to each other after adhesion. On the other hand, in the part where the mold temperature is relatively low, only the low-melting resin powder or only the low-melting resin powder and the middle-melting resin powder are melted into an adhesive state. Weaker than force. This is because the high melting point resin powder is not melted and adhered. Therefore, a large amount of the inorganic powder adheres to the high temperature part, but a large amount of the inorganic powder does not adhere to the low temperature part. Therefore, seizure can be prevented in a high-temperature portion due to casting, and no release agent remains in a low-temperature portion. The resin powder may be attached to the inorganic powder in advance, and they may be mixed and applied to a mold.

Further, if necessary, a powder is formed by adhering one of the resin powders to one of the inorganic powders. For example, nylon powder is attached to aluminum powder to
And a polyethylene powder is adhered to diatomaceous earth to form a second powder. These first powder and second powder
The high thermal conductivity of the aluminum powder and the high thermal insulation of the diatomaceous earth can be utilized according to the temperature distribution of the mold by mixing and using the powders of the above.

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 by mixing paraffin powder (melting point: 46 ° C.) and polycarbonate powder (melting point: 220 ° C.) at a weight ratio of 1: 1. Then, talc (particle size: 2 μm) was prepared as an inorganic powder. These were mixed to form a powder release agent. Comparative Example 1 was a paraffin powder and talc, Comparative Example 2 was a polycarbonate powder and talc, and Comparative Example 3 was a polyethylene powder (melting point 13
7 ° C.) and talc.

Applying the mixed powder release agent 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 Melting temperature 700 ° C Alloy ADC10 Product The product shown in Fig. 1 was cast using a test die.
(Product weight 0.6 kg) Casting pressure 760 kg / cm ² Injection speed 1 m / s

In the product of FIG. 1, part A is the part farthest from the gate, and part C is the part closest to the gate. For directional solidification, the mold temperature is higher near the gate, and solidification starts from the farthest point from the gate. Therefore, A
Part B, part B, and part C are a low-temperature part, a medium-temperature part, and a high-temperature part, respectively. When the powder release agent according to the product A of the present invention is applied to the mold,
Since paraffin has a low melting point, it melts on the entire surface of the mold and adheres in an adhesive state. On the other hand, polycarbonate did not melt and adhere to the low temperature part because of its high melting point, but melted and adhered in the high temperature part. Therefore, since the adhesive strength is weak at the low temperature part and becomes strong at the high temperature part, the talc adhered to the high temperature part to form a relatively thick release agent layer, whereas the low temperature part formed a thin release agent layer. Formed. On the other hand, in Comparative Example 1, there was a tendency that talc was not sufficiently adhered in the high-temperature part and too much adhered in the low-temperature part. In Comparative Example 2, talc was not sufficiently adhered in the low-temperature portion or the medium-temperature portion. In Comparative Example 3, talc was sufficiently adhered in the medium-temperature portion, but was not sufficiently adhered in the high-temperature region of the mold. Table 1 shows the experimental results.

(Table 1) Part A (low temperature) Part B (medium temperature) Part C (high temperature) A of the present invention A Good Good Good Good Good Comparative Example 1 × release agent deposition (large) △ seizure (small) × Seizure (Large) Comparative Example 2 × Galling × Galling ○ Good Comparative Example 3 △ Demolding agent deposition (small) ○ Good × Seizing (medium)

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

Specific Example 2 As the product B of the present invention, a resin powder in which paraffin and polycarbonate were mixed at a weight ratio of 2 to 8 was prepared. Mica having a particle size of 2 μm was prepared as an inorganic powder. This was mixed to form a powder release agent. Further, as the product C of the present invention, a resin powder in which paraffin, polycarbonate and nylon were mixed at a weight ratio of 2: 5: 3 was prepared. In addition, mica having a particle size of 2 μm was prepared as an inorganic powder, and a powder release agent was prepared by mixing these. A water-soluble emulsion release agent was prepared as Comparative Example 4, paraffin and the above talc as Comparative Example 5, a mixture of polycarbonate and the above talc as Comparative Example 6, and a mixture of nylon and the above talc 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 ° C, 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) Product B of the present invention B Good △ Seizure (small) ○ Good Product of the present invention C Good ○ Good ○ Good Comparative example 4 × Bad run of hot water × Seizure (medium) △ Slightly poor runway Comparative example 5 × Deposit of release agent (Large) × Seizure (Large) △ Seizure (Small) Comparative example 6 △ Scratching ( Small) △ Seizure (Small) ○ Good Comparative Example 7 × Galling (Large) ○ Good △ Galling (Small)

As is clear from Table 2 above, in the case of the products B and C of the present invention, since the low melting point paraffin is melted even in the thin portion where the temperature is relatively low, the required amount of talc adheres and no galling occurs, and Since polycarbonate and nylon having a melting point are also mixed, talc is prevented from adhering more than necessary, and deposition of a release agent can be prevented. In addition, a desired amount of talc was adhered to the thick portion which became a high temperature portion due to the melting of the high melting point material, and no seizure occurred.

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

2200 tons Die casting machine Melting temperature 680 ° C Alloy ADC10 Product Housing body (weight 10kg) Casting pressure 700kg / cm ² Injection speed 50m / s

(Table 3) High-temperature part (thick part) Low-temperature part Invention product D △ Sink nest (small) ○ Good run-off Comparative example 8 × Sink nest (large) △ Slight run-off

In the high-temperature portion, a large amount of aluminum powder adheres, thereby improving heat transfer. Therefore, it was possible to increase the cooling rate, and shrinkage cavities decreased. Also, a large amount of diatomaceous earth powder having a large heat insulating property adhered to the low temperature part, and thus the heat insulating property was improved. As a result, the temperature of the molten metal can be prevented from lowering, and the molten metal flowability is improved.

[0025]

According to the powder releasing agent for a mold of the present invention described in detail above, the amount of the inorganic powder adhered can be controlled in accordance with the temperature of the mold, resulting in seizure and remaining of the releasing agent. Disadvantages can be prevented. In other words, in the high temperature part of the mold, both the low melting point and the high melting point resin powder increase the adhesiveness of the mold surface, so that the amount of the inorganic powder attached is large. Therefore, the releasability is improved and seizure can be prevented. Also, since only the low melting point resin adheres to the low temperature part of the mold, the adhesiveness is weak and the amount of the inorganic powder adhered is small, so that no release agent remains. Further, since different kinds of inorganic powders can be dispersed according to the temperature of the mold, the performance of the release agent required by the parts of the mold can be selectively and effectively exhibited.

[Brief description of the drawings]

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

[Explanation of symbols]

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-92232 (JP, A) JP-A-4-279242 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22C 3/00

Claims (1)

(57) [Claims] At least two kinds of trees having different melting points.
Fat powder and at least two kinds of inorganic powders,
Resin powder of the same type is pre-adhered to inorganic powder of the same type and mixed
A powder release agent for casting, characterized in that: