JPS63224861A - Single crystal casting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a casting apparatus for single-crystal castings that is capable of preventing mold damage caused by rapid temperature changes.

[Conventional technology]

In a casting machine for single-crystal casting, a mold filled with a metal material is placed on a mold table that can be raised and lowered, and as the mold table is lowered, the metal material is heated using an induction heating coil that surrounds the mold and has a small width in the vertical direction. There is a method in which a single crystal casting is cast by induction heating and melting from the lower part, and cooling the molten metal in a mold stand and solidifying from the lower part.

[Problem that the invention seeks to solve]

Casting single-crystal castings takes a long time and there is a large temperature difference between the molten metal and the unmolten metal, so the mold can be damaged by heat cycles and internal stress caused by rapid temperature changes. There were drawbacks.

In order to eliminate the above-mentioned drawbacks, the present invention provides a casting apparatus for single-crystal castings that can prevent damage to the mold due to sudden temperature changes between the molten metal part and the unmelted metal material part. The purpose is to

[Means for solving problems]

In order to achieve the above-mentioned object, this invention has a graphite cylindrical body 4 surrounding the mold 1 placed above a heating coil 3 having a small width in the vertical direction and heating the metal material 2 filled in the mold 1 by induction.
is formed into a tapered tube shape that widens upward, and
This cylindrical body 4 is induction heated by an induction heating coil (V5) wound around its outer circumference, and the mold 1 is preheated by the radiant heat of this cylindrical body 4.

[Effect]

Radiation heat is inversely proportional to the fourth power of the size of the heat transfer space, but since the distance between the cylindrical body 4 and the mold 1 is made larger at the upper part, the lower part of the mold 1 where the two parts of the unmelted metal material are Molten metal 6
By preheating the mold 1 to a high temperature close to the temperature of the mold 1 and lowering the temperature of the upper part with a uniform temperature gradient, it is possible to prevent damage to the mold 1 due to sudden temperature changes.

〔Example〕

FIG. 1 and FIG. 2 show an embodiment of this invention.
A mold 1 filled with a metal material 2 is placed on a mold table 7 that can be raised and lowered, and the metal material 2 is continuously induction heated by an induction heating coil IL/3 surrounding the mold 1 while lowering the mold table 7. It is designed to dissolve. The metal material 2 is a pellet, billet, or ingot that is mixed so that the molten metal 6 has a predetermined composition, and is poured into the mold 1 in a vacuum tank 8 or with an inert gas to prevent oxidation and increase the purity of the molten metal 6. It is filled in an atmosphere by a material supply device (not shown). The mold 1 is fixedly installed in a vertical bottomed cylindrical container 9 filled with sand 10, and the container 9 is placed on the mold table 7 via a high alumina ceramic mold table 11 having a high heat transfer coefficient. It will be placed.

This mold stand 7 can appropriately control the descending speed,
A preparation chamber 12 for the mold 1 is provided in the lower part. The heating coil 3 surrounds the outer periphery of the cylindrical container 9 and is wound vertically with as small a width as possible. For example, by inputting high frequency power, the metal material 2 is induction heated by electromagnetic induction and melted in a short time. It is supposed to be done. The vacuum tank 8
A temperature detector 13 such as a molybdenum sheathed thermocouple with a ceramic protection tube is inserted through the upper surface of the molten metal 6 to detect the temperature of the metal material 2 in contact with the molten metal 6. Accordingly, the electric power j· applied to the heating coil A/3 and the descending speed of the mold table 7 are appropriately controlled. Further, an internal operation window 14 and a monitoring window 15 are provided on the upper surface of the vacuum tank 8. The mold stand 7 is made of heat-resistant metal and can be appropriately cooled by passing cooling water through it, for example. The melting operation is performed while lowering the mold table 7, so the metal material 2 in the mold 1 is melted from the bottom to the top, and the molten metal 6 is cooled in the mold table 7 and solidified from the bottom to form a single crystal casting. Can be cast.

Immediately above the heating coil 3, a graphite cylindrical body 4 surrounding the outer periphery of the cylindrical container 9 is disposed in a tapered tube shape that widens upward, and the outer periphery of this cylindrical body 4 has heat resistance. The induction heating coil 5 is wound with a heat insulating material 16 in between. The cylindrical body 4 is continuously heated by electromagnetic induction by applying high frequency power to the heating coil/L 15, and the mold 1 in the cylindrical container 9 is preheated by the radiant heat of the cylindrical body 4. It has become. The radiant heat is generally transferred in inverse proportion to the fourth power of the size of the heat transfer space.
Since the gap between the mold 1 and the mold 1 is set so that the upper part is larger, the 2 parts of the unmelted metal material are heated to a high temperature close to the temperature of the 6 parts of the molten metal in the lower part of the mold 1, while the upper part is kept at a low and uniform temperature. It is possible to preheat with a gradient to prevent sudden temperature changes.

The reason why the cylindrical body 4 is heated by induction using the heating coil 5 is to facilitate temperature control, and the mold 1 can also be preheated by using the entire body as a resistance heating body.

〔Effect of the invention〕

According to the present invention, in a casting apparatus for single crystal casting, a graphite cylindrical body surrounding the mold is placed above a heating coil having a small width in the vertical direction to inductively heat a metal material filled in a mold. In addition to forming and arranging the
This cylindrical body is heated by induction using an induction heating coil wrapped around its outer circumference, and the radiated heat from this cylindrical body preheats the mold with a uniform temperature gradient from a high temperature close to that of the molten metal to a lower temperature at the top. The effect is that damage to the mold due to rapid temperature changes between the mold and the unmelted metal material can be prevented.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a partial vertical cross-sectional view of the entire apparatus shown in FIG. l... Mold, 2... Metal material, 3.5... Heating coil, 4... Cylindrical body, 6... Molten metal, 7... Mold stand.

Claims (1)

[Claims] 1) A mold filled with a metal material is placed on a mold table that can be raised and lowered, and as the mold table is lowered, the metal material is heated by induction using an induction heating coil with a small width in the vertical direction that surrounds the mold, starting from the bottom. In a casting device that casts a single crystal casting by melting the molten metal and solidifying it from the lower part by cooling the molten metal in a mold stand, a graphite cylindrical body surrounding the mold is placed above the heating coil in an upwardly expanding taper. A single-crystal casting, characterized in that it is formed and arranged in a tubular shape, and that the tubular body is heated by induction with an induction heating coil wound around its outer periphery, and the mold is preheated by the radiant heat of the tubular body. casting equipment.