JPH05161957A - Casting method and mold - Google Patents

Abstract

PURPOSE:To easily manufacture a casting without blow hole defect and to improve quality and precision. CONSTITUTION:An upper mold 1 and a lower mold 2 are formed of a metallic mold and a core 3 is formed of a shell core. The core 3 is supported with the upper mold 1 and the lower mold 2 and a cavity part 3a of the core 3 is communicated with a sucking hole 6 and an exhaust hole 7. By the air or liquefied nitrogen gas flowing the cavity part 3a, molten metal heat generated at the time of pouring the molten metal is absorbed and solidified cooling of the molten metal is promoted. Further, gas generated from the core 3 at the time of pouring the molten metal is sucked in the cavity part 3a and exhausted to the outer part together with the air or the liquefied nitrogen gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method in which cavities are less likely to occur.

[0002]

Shrinkage cavities are apt to occur in the thick part of a casting, and a core containing a chill is used to accelerate solidification cooling of the thick part. If the portion is larger than the chill, the cooling effect is small and it is difficult to eliminate shrinkage cavities (for example, JP-A-51-62133).

As another method for cooling the thick portion of the casting,
There is a device provided with a cooling nozzle for cooling the mold with pressure air, and this device includes a temperature sensor, a multiplexer, a thermoelectric temperature converter, and an A / D converter embedded in the mold in addition to the cooling nozzle. There is a problem that a device, a computer, a D / A converter, a control display panel and the like are required, and the device becomes complicated (for example, Japanese Patent Laid-Open No. 57-124566).

In addition, as another casting method, an actual casting method 61-
There is one such as shown in Japanese Patent No. 182641 which, after inserting a skirting board of a core into a suction tube, exerts a suction action to reduce the pressure inside the core, and when the molten metal comes into contact with the core, It is a casting method in which the gas generated from the core is sucked into the suction pipe through the skirting board and discharged to the outside to prevent the occurrence of nest defects, but the gas generated from the core does not diffuse into the molten metal. However, there is a problem that the effect of promoting solidification cooling of the molten metal is small.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a casting method in which shrinkage cavities such as shrinkage cavities and blow holes are less likely to occur. .

[0006]

DISCLOSURE OF THE INVENTION The present invention is a casting method for pouring molten metal while depressurizing the inside of the core by exerting a suction action on the core, making the core hollow, and air or air in the hollow portion. It is characterized in that liquid nitrogen gas is circulated to promote forced cooling from the inside.

[0007]

[Function] Since the inner core is decompressed by exerting a suction action on the core, air or liquid nitrogen gas quickly flows through the cavity, and the heat of the molten metal is absorbed by the air or liquid nitrogen gas.
The solidification cooling of the molten metal is promoted, and when the molten metal comes into contact with the core, the gas generated from the core is absorbed in the cavity and does not diffuse into the molten metal.

[0008]

1 shows a mold used in the present invention, in which an upper mold 1 and a lower mold 2 are formed of a mold, and a core 3 having a cavity 3a is formed of a shell core. A sprue 4, a cavity 5, an intake hole 6 and an exhaust hole 7 are formed in the upper mold 1 and the lower mold 2, respectively, and the core 3 is made into a skirting board 3 during mold matching.
It is supported by the upper mold 1 and the lower mold 2 via b, the cavity 3a communicates with the intake hole 6 and the exhaust hole 7, and the exhaust hole 7 is connected to one end of the suction pipe 8 and The end is connected to suction means (not shown).

When the liquid nitrogen gas flows through the hollow portion 3a of the core 3, a liquid nitrogen gas supply means (not shown) is connected to the intake hole 6.

Next, the casting operation will be described. After arranging the core 3 at a predetermined position of the lower mold 2, the upper mold 1 and the lower mold 2 are matched to form a mold. Next, suction means (not shown)
Is activated to reduce the pressure in the cavity 3a, air or liquid nitrogen gas is sucked into the molds 1 and 2, and flows through the cavity 3a. After that, when the molten metal is poured into the cavity 5 when it is poured from the spout 4, the heat of the molten metal is absorbed by the air or liquid nitrogen gas flowing through the cavity 3a to accelerate the solidification cooling of the molten metal. Moreover, the gas generated from the core 3 when the molten metal comes into contact with the core 3 is absorbed in the cavity 3a, and the suction means (Fig. (Not shown) and does not diffuse into the melt.

The present invention can be applied to a casting method using a die having a self-hardening core such as a shell core, and is effective in, for example, a gravity die casting method and a low pressure casting method.

[0012]

According to the present invention, the solidification cooling of the molten metal is promoted, and the diffusion of gas into the molten metal is prevented.
Since a cast product having no cavities can be easily manufactured, and the core has a suction action, the suction casting method can be automatically achieved, the molten metal is improved, and the quality of the cast product is improved. Further, since the core is supported by the upper mold and the lower mold, the core can be positioned easily and surely, so that a casting of good quality and precision can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a mold used in the present invention.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Core 3a Cavity

Claims (3)

[Claims] 1. A casting method in which molten metal is poured while depressurizing the inside of the core by exerting a suction action on the core, the core is hollowed, and air or liquid nitrogen gas is circulated in the hollowed portion from the inside. A casting method characterized by promoting forced cooling. 2. The casting method according to claim 1, wherein the core is formed of a shell core. 3. A mold comprising a core according to claim 1 or 2.