JPH1058090A - Resin core for casting light alloy in die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a safety and quality because gas is exhausted through a opening hole part without raising an inner pressure even if molten metal is flowed into a hollow part during casting in a die casting from happening by providing an opening hole parts communicated with the outer air in a synthetic resin-made core having a hollow part. SOLUTION: The synthetic resin-made core 4 is set to a fixed die 1 with core print parts 4a, and a movable die 2 and a sliding die 3 are shifted to form a cavity 5 between the synthetic resin-made core 4 and the die. At the time of pouring the molten light alloy of aluminum alloy, etc., into this cavity 5 at high pressure and high speed, the molten metal is flowed into the cavity 5 and filled up. In the case of using the synthetic resin-made core 4, a ceramic filter 4b having a fine hole communicated with the outer air, are arranged and the produced fume is exhausted through the fine holes in the core print parts and the pressure in the inner part of the synthetic resin-made core 4 is not raised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to die casting of a light alloy such as an aluminum alloy, and more particularly to a light alloy die casting method using a synthetic resin core.

[0002]

2. Description of the Related Art A die casting method of a light alloy such as an aluminum alloy is well known as a method capable of mass-producing inexpensive aluminum castings due to its high mass productivity. However, the shape of the casting produced by die casting is greatly restricted by the mold structure, and the sand core used in other casting methods cannot be used due to insufficient strength. Almost no production. The reason is that, in the die casting, the pressure applied to the molten metal or the mold at the time of casting is large and the pressure is rapidly increased, so that the sand core cannot withstand the impact pressure and breaks.

[0003] In order to cast a light alloy die casting having a shape having a complicated internal structure, it can withstand high pressure,
In addition, the development of a die-casting technique using a synthetic resin core as an inexpensive and reproducible core material is being promoted.

[0004]

When a resin core is applied to a core of a large die cast product, no problem occurs if the resin core can be manufactured in a solid state. However, molding a thick resin requires a long time to solidify the resin, which is inferior in mass productivity and requires a large amount of resin, which has been difficult to put into practical use. Therefore, in such a case, a hollow resin core is applied. The hollow core is manufactured by integral molding in which the inside is pulled out with a mandrel, or split molding in which the core is divided into several parts and then joined.

[0005] The hollow resin core must have an appropriate thickness of at least 8 mm in order to withstand the casting pressure of die casting, but since it is relatively thin, it comes into contact with a high-temperature molten metal. Its surface temperature rises and softens. Further, there may be a case where a locally weak part such as a thin part of the core or a joint surface of the core is damaged. In this case, not only can a sound casting not be manufactured, but also the molten resin flows into the hollow part from the damaged part of the resin core, so that the resin is exposed to high temperature and burns, and at the same time, smokes and the internal pressure rises. A part of the resin that has become hot may be broken and scattered by impact, which is dangerous for work.

[0006] As a countermeasure, use of a resin core using a material having a high melting point and high strength at high temperature, a method for preventing a rise in temperature of the resin core, casting conditions, and the like are applied. The application of a material having a high melting point and a high strength at high temperature has a problem that the material cost is high and it is difficult to remove and reuse the resin core after casting. Japanese Patent Application Laid-Open No. 7-1079 discloses a method of performing casting while continuously flowing a fluid through a hollow resin core for the purpose of preventing a temperature rise of the resin core. There is a new problem that the structure of the mold is complicated due to the necessity of forming a fluid flow path in the mold and that the fluid leaks during casting. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily preventing the molten resin from being scattered due to combustion and smoke caused by the damage of the resin core when a hollow resin core is used.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to cast a light alloy such as an aluminum alloy into a gap between an inner surface of a mold and an outer surface of a core. A light-alloy die-casting resin core for use in die-casting for producing a resin, wherein the core has a hollow portion, and the hollow portion is communicated with the atmosphere at a baseboard portion. Here, the baseboard portion refers to a portion where the core is fixed to and in contact with the mold. Further, it is preferable that the hollow portion of the resin core for light alloy die casting is communicated with the atmosphere through at least one hole having a diameter of 0.05 to 0.2 mm.
If the diameter is smaller than 0.05 mm, it is difficult for gas to escape during combustion of the resin core, and if the diameter is larger than 0.2 mm, the light alloy melt that has flowed into the baseboard tends to enter the resin core. . In addition, at least one filter made of ceramic or the like having a hole having a diameter of 0.05 to 0.2 mm is preferable.

[0008]

Embodiments of the present invention will be described.
FIG. 1 shows an embodiment of the die casting method using the resin core of the present invention. The mold is composed of a fixed mold 1, a movable mold 2, and a sliding mold 3, and a hollow synthetic resin core 4 is
a is positioned by fitting into the concave portion of the mold formed by the concave portions of the fixed die, the movable die and the sliding die. A ceramic filter 4b having an average pore diameter of 0.07 mm is provided in the baseboard portion 4a of the synthetic resin core, and the ceramic filter 4b is formed on a parting surface of the mold and communicates with the outside through the communication hole 7 which is opened outside the mold. The hollow portion 6 inside the resin core communicates with the outside air.

A process of performing die casting using a synthetic resin core will be described. The synthetic resin core 4 is set on the fixed mold 1 at the baseboard portion 4a, and the movable mold 2 and the sliding mold 3 move.
A cavity 5 is formed between the synthetic resin core 4 and the mold. When a light alloy such as an aluminum alloy is injected into the cavity 5 at a high pressure and a high speed, the molten metal flows into the cavity 5 to be filled. At this time, for example, if there is a thin portion of the synthetic resin core due to molding failure, or if there is a bonding failure with a core formed by joining two or more parts, In some cases, the core was not able to withstand high temperatures and pressures, and the core was damaged, causing a high-temperature molten metal to flow into the hollow portion 6. In this case, the resin burns and emits smoke due to the heat of the inflowing molten metal. In the case of the synthetic resin core of the present invention shown in FIG. 1, a ceramic filter 4b having pores communicating with the outside air is provided, and the generated smoke is
It is discharged through the pores of the baseboard, and the pressure inside the synthetic resin core 4 does not increase. However, in the case of the conventional synthetic resin core having no opening shown in FIG. 2, the internal pressure of the hollow portion 6 increases as the synthetic resin core burns. When the movable mold 2 and the sliding mold 3 are moved to open the mold and remove the casting from the mold, the molten resin is ejected from the gap between the casting and the synthetic resin core, or In some cases, the baseboard was broken by losing the internal pressure and the core was damaged.

[0010]

According to the present invention, since a synthetic resin core having a hollow portion is provided with an opening communicating with the outside air, even if molten metal flows into the hollow portion during die casting, the gas is opened without increasing the internal pressure. Since it is released through the part, the safety and quality are remarkably improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

Reference Signs List 1 fixed type, 2 movable type, 3 sliding type, 4 synthetic resin core, 5 cavity, 6 hollow portion, 7
Communication hole

Claims (3)

[Claims] 1. A light-alloy die-casting resin core for use in die-casting for producing a casting by injecting a light alloy such as an aluminum alloy into a gap between an inner surface of a mold and an outer surface of a core, A resin core for light alloy die casting, wherein the core has a hollow portion, and the hollow portion is communicated with the atmosphere at a baseboard portion. 2. The hollow part of the resin core for light alloy die casting is communicated with the atmosphere by at least one hole having a diameter of 0.05 to 0.2 mm. The resin core for light alloy die-casting described. 3. The hollow part of the resin core for light alloy die casting is communicated with the atmosphere by at least one filter having a hole having a diameter of 0.05 to 0.2 mm. Item 2. A resin core for light alloy die casting according to item 1.