JPS5913257Y2 - Raw material addition mechanism of crystal growth furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a raw material addition mechanism for a crystal growth furnace for growing ferrite single crystals used in magnetic heads and the like.

The Bridgman method has been used to grow ferrite single crystals suitable for magnetic heads.

This is a method in which a crucible containing raw materials is lowered at a predetermined speed through a furnace core tube that has a temperature gradient suitable for crystal growth in the axial direction to generate and grow seeds.

If the shape of the single crystal to be produced is small, it is possible to put all the raw materials in the crucible and melt it in the highest temperature scorching part of the furnace. When using a crucible to charge the necessary raw materials, it is not possible to melt the crucible unless the area of the highest temperature scorching part of the furnace is increased or the scorching temperature is raised to near the melting point of platinum, the raw material for the crucible.

To address this drawback, a raw material addition method has been adopted.

In this method, an amount of raw material that can be melted in the scorching heat of the furnace is placed in the crucible, the crucible is lowered after it is melted, and the raw materials are successively added as it descends.

FIG. 1 schematically shows a crystal growth process in a conventional raw material addition method.

As shown in the figure, the platinum crucible 1 is moved sequentially through the temperature gradient 2 of the furnace to positions ae to grow a single crystal.

That is, a is the position where the raw material in the crucible is completely melted, and b
-d indicates the start, middle, and end positions of raw material addition, and e indicates the end position of crystal growth.

At this time, the additive raw material 3 is supplied to the crucible through the platinum additive pipe 4, but since the distance between the set position of this pipe and the crucible position gradually increases, the raw material cannot be accurately fed due to the influence of convection in the furnace. The raw material does not enter the crucible, resulting in fewer crystals than expected, and the falling raw material adheres to the surface of the furnace core tube.

In order to prevent this, it is possible to use a large crucible such that the inlet of the crucible is located directly near the outlet of the pipe at the above position d, but this would result in a large dead space of the crucible for the crystal to be produced. However, it cannot be denied that the utilization rate of expensive crucibles is low.

The present invention aims to provide a raw material addition mechanism for a crystal growth furnace that can eliminate the above-mentioned drawbacks, that is, a mechanism that can lower the raw material addition pipe in accordance with the descending speed of the crucible that descends in the furnace. It is something to do.

FIG. 2 shows a schematic diagram of the mechanism of the present invention.

The motor 10 is a motor that moves the raw material addition pipe 11 and the crucible 12 in the axial direction of the furnace core tube 13, and its power is transmitted via gears 14a, 14b, 14C, 14d, and a chain 15 to bearings 16a, It is transmitted to the gear shirts t-17a, 17b supported by block 16b, and also to the crucible transport means indicated by block 18.

The rotation of the gear shaft is controlled by the guides 19 a , 19
The slider 20 guided by the bearing 16b is moved up and down, thereby the pipe 21 fixed to the bearing 16a.
The movable pipe 22, which is inserted therein, is moved up and down.

A raw material addition pipe 11 is attached to the tip 22a of the moving pipe 22, and is also controlled by the motor so that it can move up and down within the furnace core tube.

From the upper end of the fixed pipe, a predetermined amount of raw material 24 from the raw material hopper 23 is fed through rollers 25a, 25b, 25C1 addition roller 26, and guide pipe 27.

The addition roller is program-controlled by the motor 10.
In connection with the operation, control is performed so that the raw material is sent to the addition pipe 11 at the necessary time for adding the raw material.

The crucible transfer means 18 is configured to drive a moving table 28 supporting the crucible 12 in synchronization with the motor.

29 is a furnace body, and 30 is a heater.

According to the present invention, both the raw material addition pipe and the crucible can be lowered in the furnace core tube in a synchronous manner by the power of the program-controlled motor, ensuring that the raw material fed from the hopper does not fall out. It can be placed in a crucible at any time, and crystals of a desired size can be easily produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional raw material addition method, and FIG. 2 is a schematic diagram of the structure of the mechanism of the present invention. Explanation of main drawing numbers 13... Furnace core tube, 12...
... Crucible, 11 ... Pipe for adding raw materials.

Claims (1)

[Scope of utility model registration request] In a raw material addition mechanism of a crystal growth furnace that supplies additional raw material to a crucible whose transfer is controlled in the axial direction of a furnace core tube through a raw material addition pipe during its transfer path, a raw material hopper and a material disposed at an outlet of the raw material hopper are provided. An addition roller that controls the discharge of the raw material, a fixed pipe that guides the raw material discharged from the addition roller, and a fixed pipe that is disposed outside the fixed pipe and has one end movable in the extending direction of the fixed pipe. A moving pipe attached to the slider and having the other end disposed in the opening of the crucible, crucible transfer means for controlling the movement of the moving stage supporting the crucible in the furnace core tube, and one power source, One power source is the addition roller, the slider,
and a raw material addition mechanism for a crystal growth furnace, in which the crucible transfer means is synchronously driven, and the relative position of the moving pipe with respect to the crucible is constant in a region where the added raw material is supplied.