JPH0623482A - Water soluble core for high pressure die casting - Google Patents

Abstract

PURPOSE:To allow a core to bear a high pressure die casting and to improve the collapsibility by blending and forming a core with fine particles and powder of fossil seashell, laminating two or more kinds of coating agent on the surface of the core, heating and drying it. CONSTITUTION:More than 95 parts of fine particles and powder of fossil seashell as base material of the core and <=5 parts thermosetting resin as a binder and gypsum are blended and water is added to it to make a slurry state. Then, the slurry is poured into a forming die and after pressurizing, by heating it at 100-300 deg.C for 10-30min, the slurry is hardened and formed to obtain a core body A. On the core body A, a first coating agent is applied and dried to make a first coating layer (a) and successively, by brush-applying a second coating agent and drying, a second coating layer (b) is formed and further, by dipping it into a heat resistant coating paint, a third coating layer (c) is formed and dried to finish the core. Therefore, even an aluminum alloy is cast in the high pressure, penetration of the aluminum into the core and the casting deffect caused by the crack of the core can be prevented. Further, the thermosetting resin of the binder is easily collapsed by dipping it into water after casting caused by heating at the time of casting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble core that can be used in the undercut portion of high pressure die casting.

[0002]

2. Description of the Related Art As a mold used in high pressure casting such as a die casting method, a precision-processed and strong special steel is used, so that the casting has an undercut portion or a bag-like portion. However, due to restrictions, the shapes of the products that can be made are limited. Therefore, various sand cores have been studied in order to solve the problem of casting a product having such an undercut portion and a bag-shaped portion.

However, as a sand core used in die casting, it must be able to withstand the molten metal that is press-fitted at high pressure.
Further, there is no pouring of the molten metal into the sand core, and therefore a strong core is required, and the product is required to have a smooth casting surface. When a sand core is used, the method of removing the sand core from the product after casting is a problem.
The sand core is incinerated by heating for 1 hour or more, and the sand is removed by applying a vibration with an air hammer or the like, but there are many problems in terms of cost, man-hours and quality.

In order to solve these problems, water-soluble cores, which allow cores to be easily eluted from a product after casting, have been studied since the 1940s. With regard to water-soluble cores, Japanese Patent Publication No. 48-8368 and Japanese Patent Publication No.
No. 8-17570 is known. In all of these methods, a refractory is added to a salt as a reinforcing material, or the above-mentioned inorganic salt powder is pre-dried and then molded at high pressure. However, since both methods mainly use salts, not only the manufacturing process is complicated, but also the production cost of the core, the storage of the core, and the time required for the elution of the core are problems in practical use. There is.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned conventional drawbacks, and is a core having a simple manufacturing method, strength, and good disintegration, and further, the manufacturing cost is low and the molding is performed. The purpose of the present invention is to provide a water-soluble core for high-pressure die casting, which is easier than the conventional water-soluble core for storage of the latter core and can be easily eluted and removed from the product after casting.

[0006]

[Means for Solving the Problem] As a means for achieving this, the present invention uses fine particles and powders of fossil shells (fossil Hokuriku shellfish) as a base material for cores and a small amount of a thermosetting resin as a binder. (Phenol resin) and gypsum are mixed, and water is added to the mixture to form a slurry, which is then poured into a molding die or 100 to 300 after pressurization.
The core body was heated and cured at 10 ° C. for 10 to 30 minutes, and a mold coating agent was applied to the core body.

[0007]

EXAMPLE An example of the water-soluble core for high pressure die casting according to the present invention will be described with reference to FIGS. 1 and 2. 50 parts of shell fossil powder (100 mesh or less), shell fossil fine particles (30
Mesh) 46 parts, thermosetting resin (phenolic resin) 3
Parts and 1 part of gypsum were mixed, and 35 parts of water was added to form a slurry. And pour this into the mold 200 ° C
Then, the core body A was cured and molded for 20 minutes to obtain a core body A in FIG. Zircon flower (10
μm), 1 part of water glass (molar ratio 2.0), and 5 parts of water were applied and dried at room temperature for 30 minutes to obtain a first mold coating layer a in FIG. Next, a second coating agent consisting of 1 part of gypsum, 1.5 parts of scaly graphite, and 12 parts of water was applied by brushing, and dried at room temperature for 30 minutes to obtain a second coating layer b of FIG.
And Further, it was dipped in a heat resistant coating composed of silicone resin and graphite for about 30 seconds to form the third coating type layer c in FIG. 2, dried for about 60 minutes at room temperature, and then dried by heating at 300 ° C. for about 20 minutes. The dried core was set in a mold and cast using an 800-ton die casting machine at an aluminum alloy (ADC12), a molten metal temperature of 700 ° C., and a casting pressure of 900 Kgf / cm ² . After immersing the product in water for about 20 minutes and jetting a jet water stream to the core portion of the product, the core could be easily eluted in 1 to 2 minutes. The performance of the cast product was also good.

Next, a second embodiment of the water-soluble core for high pressure die casting according to the present invention will be described with reference to FIGS. 1 and 2. 50 parts of shell fossil powder (100 mesh or less), 46 parts of shell fossil fine particles (70 mesh), 3 parts of thermosetting resin (phenol resin) and 1 part of gypsum are mixed, and 37 parts of water is added to this to form a slurry. And Press the slurry with a mold and press 1
It was cured and molded by heating at 90 ° C. for 25 minutes to obtain a core body A in FIG. To this core body A, a first mold coating agent consisting of 5 parts of zircon flour (10 μm), 5 parts of dextrin, and 12 parts of water was applied by dipping, and dried at room temperature for 60 minutes to obtain the first mold coating layer of FIG. a. Next, a second mold coating agent consisting of 1 part of gypsum, 1.5 parts of flake graphite, and 12 parts of water was applied by dipping and dried at room temperature for 60 minutes to obtain a second mold coating layer b in FIG. Further, it was dipped in a heat-resistant paint composed of silicone resin and graphite for about 20 seconds to form the third coating type layer c in FIG. 2, dried for about 60 minutes at room temperature, and then heated and dried at 400 ° C. for 20 minutes. The dried core is set in a mold, and an aluminum alloy (ADC12) is used by using a 800 ton die casting machine.
Casting was performed at a molten metal temperature of 700 ° C. and a casting pressure of 900 Kgf / cm ² . After soaking the product in water for about 20 minutes, jetting a jet water stream to the core part of the product
The core could be easily eluted in 2 minutes. The performance of the cast product was also good.

Next, a third embodiment of the water-soluble core for high pressure die casting according to the present invention will be described with reference to FIGS. 1 and 2. 50 parts of shell fossil powder (100 mesh or less), 45 parts of shell fossil fine particles (50 mesh), 2 parts of thermosetting resin (phenol resin) and 3 parts of gypsum are mixed, and 37 parts of water is added to this to form a slurry. And Pour the slurry into the mold,
Hardened and molded by heating at 220 ° C for 15 minutes.
The core body A was used. On the core body A, a first coating agent comprising 5 parts of zircon flour (10 μm), 1 part of water glass (molar ratio 2.0) and 5 parts of water was applied by brushing, and 60
It was dried at room temperature for minutes to form the first coating type layer a in FIG. next,
It is dipped in a heat-resistant paint composed of silicone resin and graphite for about 30 seconds to form a second coating type layer b in FIG. 2 and dried at room temperature for about 60 minutes.
It was dried by heating at 400 ° C for about 20 minutes. The dried core is set in a mold, and an aluminum alloy (ADC12) is used with a 800 ton die-casting machine, the melt temperature is 700 ° C,
Casting was performed at a casting pressure of 900 Kgf / cm ² . After immersing the product in water for about 20 minutes, a jet water flow was jetted to the core part of the product, and the core could be easily eluted in 3 to 5 minutes. The performance of the cast product was also good.

As described above in the Examples, the water-soluble core for high pressure die casting of the present invention is formed by blending fine shell fossil particles and shell fossil powder, so that the shell fossil powder is a binder. Therefore, even if the amount of the original binder (thermosetting resin, gypsum) is 5 parts or less, it is possible to withstand high pressure die casting and to produce a core having good disintegration. In addition, the present invention is characterized in that two or more types of coating agents are laminated on the surface of the core,
Since it was heated and dried at 0 to 400 ° C to strengthen the coating layer,
Even when casting at high pressure, it is possible to prevent casting defects such as insertion of aluminum into the core and burred surplus due to cracks in the core. In addition, the elution of the core is
Since it is heated at 300 to 400 ° C, the thermosetting resin compounded as a binder becomes brittle, and at the same time, the core is burned by the heat during casting, so that the product after casting is immersed in water. It has an excellent effect that the child can easily collapse and can be completely eluted in 1 to 5 minutes by jetting a jet water flow.

[Brief description of drawings]

FIG. 1 is a perspective view of a core body of a water-soluble core for high pressure die casting.

FIG. 2 is a cut side view of a water-soluble core for high pressure die casting.

[Explanation of symbols]

 A core body a first type coat layer b second type coat layer c third type coat layer

Claims (3)

[Claims] 1. A fine particle and powder of shell fossil (Hokuriku shell fossil) are used as a base material of a core, and a small amount of a thermosetting resin (phenol resin) and gypsum are mixed as a binder, and water is added to this. A water-soluble core for high pressure die casting in which a core material is cast into a slurry, poured into a mold, and heated and cured at 100 to 300 ° C. for 10 to 30 minutes to apply a mold coating agent. 2. The fossil shell of claim 1 is 95 parts or more,
A water-soluble core for high pressure die casting, characterized in that fine particles and powder are appropriately blended within this range. 3. A water-soluble core for high pressure die casting, characterized in that the binder of claim 1 is contained within 5 parts, and is appropriately blended within this range.