JPH07116821A - Suction casting method - Google Patents

Abstract

(57) [Summary] [Objective] In a method of casting by sucking a molten metal into the mold by reducing the pressure in the mold, casting efficiency is improved, and contamination of the residual hot water due to return of the molten metal is prevented. [Structure] After the suction of the molten metal 16 into the mold 24 is completed,
The iron ball 34 put in the mold 24 is inserted into the sprue 28 through the upper end opening of the mold 24, and the molten metal 16 of the sprue 28 is solidified based on the cooling action of the iron ball 34.
To block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal suction casting method, and more particularly to a technical means for improving efficiency.

[0002]

2. Description of the Related Art A conventional method generally used as a metal casting method is to naturally drop a molten metal inside a mold to fill the molded portion of the mold with the molten metal. Is the way. However, in the case of this method, the momentum for filling the molten metal into the forming part is not sufficient, and therefore the surrounding of the molten metal to the thin portion is insufficient, or the gas is entrained by the turbulence of the molten metal flow and solidifies as it is. There is a problem that it causes casting defects.

The suction casting method was devised to improve this, and is mainly used for precision casting by the lost wax method. In this suction casting method, generally, the mold is set in the decompression chamber, and the molten metal is sucked into the mold from the sprue by applying a negative pressure to the mold.
Casting is conducted by guiding it to the forming part.

This suction casting method has the advantages that the molten metal can be injected quickly and quietly, it has excellent melt flowability, and the internal quality of the casting is also good.

On the other hand, however, in the case of this suction casting method,
At least the suction operation must be continued for a long time until the molten metal introduced into the product forming section inside the mold is solidified, and the operation or work of the next step cannot be performed during this time, which causes a problem of poor efficiency.

Further, in the case of this suction casting method, when the vacuum is released after suctioning for a certain period of time, the molten metal inside the mold, that is, the molten metal that once contacted the mold, returns to the molten metal reservoir such as the melting furnace due to its own weight. For example, active metals such as Ti or T
When the i alloy is cast using a ceramic mold, there is a problem that the molten metal in the reservoir is contaminated by the molten metal returned from the mold.

[0007]

The invention of the present application has been made to solve such a problem. Thus, the invention of the present application is a suction casting method for a metal, in which the inside of the mold is depressurized, and the molten metal is sucked up by the pressure difference between the inside and outside of the mold and sucked up through the gate of the mold to the upper product forming part for casting. After the suction of the molten metal into the mold is completed, the solid cooling body placed in the mold through the upper end opening of the mold is inserted into the gate and the molten metal at the gate is solidified based on the cooling action. The gate is closed by the method (claim 1).

Further, another invention of the present application is to suspend the solid cooling body with a fine wire at the upper end opening of the mold,
When the suction of the molten metal is completed, the thin wire material is melted and cut by the heating action of the molten metal, and the solid cooling body is dropped onto the molten metal port to solidify the molten metal at the molten metal port (claim 2).

[0009]

As described above, according to the first aspect of the invention, after the suction of the molten metal is completed, the solid cooling body is inserted into the sprue and the molten metal in the sprue is solidified based on the cooling action to close the same. Therefore, immediately after the suction of the molten metal is completed, the mold can be moved from the casting station and the work of the next step can be performed. This significantly improves work efficiency.

Further, according to the method of the present invention, the molten metal once in contact with the mold can be prevented from returning to the molten metal reservoir such as the melting furnace, that is, the molten metal used for the next casting. The problem of contamination due to the return of the molten metal can also be solved.

According to a second aspect of the present invention, the solid cooling body is suspended by a fine wire rod, and when the suction of the molten metal is completed, the thin wire rod is melted and cut by the heating action of the molten metal, and the solid cooling body is provided at the sprue. According to the present invention, the solid cooling body can be automatically inserted into the gate at the same time as the suction of the molten metal is completed, and the solid cooling body can be easily inserted into the gate in the depressurization system. You can In this method, a solid cooling body having a larger specific gravity than the molten metal is used.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 1, 10 is a melting furnace. The melting furnace 10 is a cold crucible type levitation melting furnace. Specifically, the melting furnace 10 has a high-frequency induction heating coil 12 arranged outside a water-cooled copper crucible 14, and melts metal by high-frequency induction heating by the high-frequency induction heating coil 12.

At this time, the molten metal 16 has a repulsive force generated between them because the magnetic field due to the current generated in the surface layer and the magnetic field due to the current generated in the wall of the crucible 14 are in opposite phase to each other. That is, it is separated from the wall of the crucible 14 by the Lorentz repulsive force. That is, molten metal 1
6 is separated from the inner wall surface of the crucible and is in a floating state.

A sleeve 18 is arranged on the upper side of the melting furnace 10, and a chamber 20 is fitted into the sleeve 18 from an upper end opening. The internal space of the chamber 20 is a decompression chamber 22, and this decompression chamber 22 is the suction hole 2
It is connected to 3.

Inside the chamber 20, a porous ceramic shell mold 24 is set. This mold 24
Has a plurality of product forming parts 26 and a sprue 38 for guiding the molten metal to these forming parts 26, and a sprue 28 is formed at the lower end. A metal note 30 extends downward from the bottom opening of the chamber 20 from the spout 28.

On the other hand, at the upper end opening of the mold 24, an iron weight 3 is placed.
2 is placed, and an iron ball 34 as a solid cooling body is suspended from the weight 32 by a wire 36. The ball 34 is located directly above the sprue 28.

Next, the results of carrying out the suction casting method of this example using this apparatus will be described in detail. In the cold crucible type levitation melting furnace 10, TiAl (specific gravity 3.8
g / cc), and the chamber 20 is fitted into the sleeve 18 and vacuum suction is performed from the suction hole 23, and the inside of the chamber 20 is depressurized to apply a negative pressure to the inside of the mold 24, and the negative pressure causes the melting furnace. The molten metal 16 in 10 was sucked into the mold 24.

At this time, the molten metal 16 in the melting furnace 10 was gently and quickly sucked up into the mold 24 through the snout 30 and the sprue 28 by the action of negative pressure to fill the inside of the mold 24.

After the suction is completed, the wire 36 that suspends the ball 34 is immediately melted by the heating action of the molten metal 16, whereby the ball 34 falls by its own weight and is inserted into the gate 28, and the ball 34 The molten metal in the sprue 28, strictly speaking, the melt in the peripheral portion of the ball 34 was solidified by the cooling action due to, and the sprue 28 was closed. The spout 28 after the ball 34 falls
The time required for the blockage was about 1 second.

When the gate 28 was closed, the mold 24 was pulled up together with the chamber 20 in preparation for the next casting. Thus, when the mold 24 was pulled up, the snout 30 was hardly melted, and there was no iron contamination of the residual hot water in the melting furnace 10. Further, since the molten metal that came in contact with the ceramic mold 24 did not return, the molten metal 16 was not contaminated due to the contact with the ceramic shell mold 24.

According to the method of this example, the residual hot water in the melting furnace 10 can be reused. Therefore, according to this method, not only the casting operation can be performed with high efficiency, but also the material yield is improved. Is obtained.

Although the embodiment of the present invention has been described in detail above, this is merely an example. For example, in the present invention, the solid cooling body can be composed of a simple substance or a composite of a heat-resistant substance such as metal, ceramic or graphite, and an air cylinder or the like as a means for inserting the solid cooling body into the gate It is also possible to use an actuator.

In addition to the above, the present invention is applicable to casting of various metals within a range not departing from the gist of the present invention.
It can be implemented in variously modified modes.

[Brief description of drawings]

FIG. 1 is a diagram of an apparatus for performing a method according to an embodiment of the present invention.

[Explanation of symbols]

 10 Melting Furnace 16 Metal Melt 24 Mold 26 Product Forming Section 28 Gate 34 Ball 36 Wire

Claims (2)

[Claims] 1. A suction casting method for a metal, wherein the inside of the mold is decompressed, and the molten metal is sucked through a gate of the mold by a pressure difference between the inside and the outside of the mold to be guided to an upper product forming part to perform casting, the inside of the mold After the suction of the molten metal into the mold is completed, the solid cooling body put in the mold through the upper end opening of the mold is inserted into the gate and the molten metal of the gate is solidified based on the cooling action. A suction casting method, characterized in that: 2. The solid cooling body is suspended by a fine wire rod at the upper end opening of the mold, and when the suction of the molten metal is completed, the thin wire rod is melted and cut by the heating action of the molten metal. 2. The suction casting method according to claim 1, wherein the molten metal in the gate is solidified by dropping the molten metal into the gate.