JPH06267652A - Vacuum heat treatment device - Google Patents

Abstract

PURPOSE:To reduce the high-frequency wave input and to suppress the deterioration of the sealing property, by covering a heating unit with a heat insulating cover which consists of a material of a high electric insulation and a low heat radiating rate. CONSTITUTION:This vacuum heat treatment device is formed of a heating unit 5 housing a heat treating part 9; a vacuum container 2 having a vacuum chamber 1 to cover the heating unit 5; an airtight seal 3 to prevent the leakage of the air in the container 2; and a coil 4 for high-frequency induction heating to heat the heating unit 5. And, in order to prevent the heat radiation from the heating unit 5, a heat insulating cover 6 which consists of material of a high electric insulation and a low heat radiation rate is provided around the heating unit 5, so as to prevent an easy flow of thermoelectric current. As a result, the heat radiation output from the heating unit 5 can be reflected by the cover 6, and the heat is made difficult to conduct to the seal 3, as well as the temperature of the heating unit 5 can be maintained at a high value. Consequently, the high-frequency wave input is reduced, and the deterioration of the sealing property can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum heat treatment apparatus for heating a high temperature in a vacuum to degas a member, by keeping a heating element at a high temperature and maintaining a high vacuum in a vacuum chamber. The present invention relates to a vacuum heat treatment apparatus suitable for heating.

[0002]

2. Description of the Related Art A conventional apparatus has a structure in which a heat reflecting plate is provided inside a cooler to suppress heat radiation from a member to be heated, as in Japanese Patent Laid-Open No. 5-9568. Further, in order to accelerate the cooling of the heating element, there has been a conventional structure in which the heating element is cooled by applying it to a cooling die as in JP-A-5-9567.

[0003]

In the above prior art, a large amount of heat escapes from the heating element by radiant heat, and a large amount of high frequency output energy for heating is required. Also, the radiant heat from the heating element heats the parts other than the sealing surface,
Due to the heat conduction of the heat, the sealing surface is heated and the sealing property is deteriorated, so that there is a problem that air leaks and the vacuum breaks.

An object of the present invention is to reduce the amount of heat escaping from the heating element, which is the above-mentioned problem, to save energy of the input current of the coil for high frequency induction heating, and to hermetically seal the radiant heat emitted from the heating element. The purpose is to suppress the conduction to the part, prevent the deterioration of the sealing property of the airtight seal part, and maintain the vacuum state. When cooling the heating element,
The heat quantity of the heating element can be quickly released.

[0005]

SUMMARY OF THE INVENTION The above object is to prevent a leakage of air into a vacuum container having a heating element for accommodating a processing component to be heated, a vacuum chamber covering the heating element, and a vacuum chamber. This is achieved by providing a vacuum heat treatment apparatus that includes an airtight seal portion and a high-frequency induction heating coil that heats the heating element in the vacuum container, by providing a heat insulating cover portion that covers the heating element. Further, in the vacuum heat treatment apparatus provided with the heat insulating cover part for covering the heat generating body, the heat generating body and the heat insulating cover part are relatively moved to each other, and the heat insulating cover part is attached and detached.

[0006]

[Function] In order to prevent heat radiation from the heating element, the electrical insulation is high so that the thermal current does not easily flow around the heating element,
Enclose the heat insulating cover part made of a material with low heat emissivity,
Since it is installed, the heat radiation emitted from the heating element can be reflected by the heat insulating cover and the temperature of the heating element can be kept high, so that the waste of high frequency input energy in the heat radiation can be reduced. Further, since other parts such as the airtight seal portion are not heated by the radiant heat, the sealability is not deteriorated and the high vacuum can be maintained. In addition, in order to cool quickly, the heat generating element or the heat insulating cover portion is moved relative to each other, whereby it can be cooled by heat radiation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum heat treatment apparatus of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view of the vacuum heat treatment apparatus of the present invention during heating, FIG. 2 is a cross-sectional view of the vacuum heat treatment apparatus of the present invention during cooling, and FIG. 3 is a conventional vacuum heat treatment apparatus having no heat insulating cover 6 and the present invention. 2 is a graph showing the heating element temperature on the horizontal axis and the high frequency input (relative ratio) on the vertical axis in the vacuum heat treatment apparatus of FIG.

First, the structure of the vacuum heat treatment apparatus of the present invention will be described with reference to FIGS. 1 and 2. The vacuum heat treatment apparatus of the present invention prevents the air from leaking into the vacuum container 2 having the heating element 5 that houses the processing component 9 to be heated, the vacuum chamber 2 that covers the heating element 5, and the vacuum container 2. Airtight seal part 3
And a high-frequency induction heating coil 4 for heating the heating element 5 in the vacuum container 2 in a vacuum heat treatment apparatus, which includes a heat insulating cover portion 6 for covering the heating element 5.
Composed. Further, in the vacuum heat treatment apparatus having the above-mentioned structure, the vacuum heat treatment apparatus of the present invention is a mechanism for moving the heating element 5 and the heat insulating cover portion 6 relative to each other so that the heat insulating cover portion 6 can be attached / detached (a lift table for the heat generating element 5). 10) and is configured.

Next, the heating process of the heating element 5 of the vacuum heat treatment apparatus having the heat insulating cover portion 6 of the present invention and the conventional vacuum heat treatment apparatus having no heat insulating cover portion 6 will be compared by experiments with reference to FIG. The conditions in the experiment are set as follows. A vacuum heat treatment apparatus having the heat insulating cover portion 6 of the present invention is referred to as a sample A, and a conventional vacuum heat treatment apparatus having no heat insulating cover portion 6 is referred to as a sample B. Next, conditions common to the sample A and the sample B will be described. The heating element 5 that houses the processing component 9 to be heated is made of a material such as graphite that has a large heat capacity and is easily induced by high frequencies. The vacuum container 2 having the vacuum chamber 1 covering the heating element 5 keeps the vacuum degree of the vacuum chamber 1 such as quartz glass at 9 × 10 ⁻⁴ Torr or less so as not to be discharged even when a voltage is applied by high frequency induction or the like. A material that is an insulator that can be used and that is not induced by high frequencies is used. The airtight seal portion 3 that prevents air from leaking into the vacuum container 2 is made of a material such as Viton rubber that releases little gas and maintains airtightness. The high frequency induction coil 4 for heating the heating element 5 in the vacuum container 2 is provided in the vacuum container 2 by a certain number of turns. Further, a thermocouple 8 for measuring the temperature of the heating element 5 is attached. The processing part 9 is in contact with the heating element 5 or can be heated by radiant heat.

Next, conditions specific to Sample A will be described.
The heat insulating cover 6 for covering the heat generating portion 5 is made of a material such as heat resistant ceramics that is chemically stable, is an insulator, and has large heat reflection and small heat radiation. The color of this material is preferably white in order to increase the heat reflection, and the shape of this material is preferably thin in order to reduce the heat capacity. Also, this heat insulating cover portion 6
Is provided with a gas vent hole 7 for venting a slight amount of generated gas from the processing component 9 and the heating element 5. Further, when the heat generating body 5 is covered with the heat insulating cover part 6, the heat generating body 5 and the heat insulating cover part 6 are arranged so as to have an appropriate gap so that the heat of the heat generating body 5 is not conducted to the heat insulating cover part 6.

Next, the experimental process will be described. (1) In sample A and sample B, the processing component 9 is placed in the heating element 5. (2) With respect to the sample A and the sample B, the evacuation hole 11 is evacuated to the pressure specified under the above conditions. (3) In sample A and sample B, a current is passed through the high frequency induction heating coil 4 to heat the heating element 5. (4) In the samples A and B, the temperature of the heating element 5 is measured by the thermocouple 8. (5) In sample A and sample B, the temperature of the heating element 5 is taken as the horizontal axis, and the relative ratio of the input amount to the high-frequency induction heating coil 4 is taken as the vertical axis. Create a graph like this.

Next, experimental results will be described. Heating element 5
The graph of FIG. 3 shows that when the target temperature for heating of the sample A is set to 800 ° C., the sample A requires 50% of the high frequency input of the sample B.

Next, the heating element 5 of the vacuum heat treatment apparatus of the present invention.
The cooling step of will be described with reference to FIG. By placing the heating element 5 of the vacuum heat treatment apparatus on the elevating table 10 and removing the cover of the heat insulating cover portion 6 from the heating element 5, the heating element is quickly cooled. Further, in this example, the heat-generating body 5 is moved to remove the cover of the heat insulating cover 6, but the heat insulating cover 6 may be moved.

[0014]

The vacuum heat treatment apparatus of the present invention has the following effects. (1) By covering the heating element 5 with the heat insulating cover portion 6, in heating the coil 4 for high frequency induction heating, it is possible to reduce the high frequency input until the target temperature of the heating element 5 is reached, and it is possible to save energy. (2) By covering the heating element 5 with the heat insulating cover portion 6, heat is less likely to be conducted to the airtight sealing portion 3, so that deterioration of the sealing property can be suppressed and the airtightness of the vacuum chamber 1 can be enhanced. (3) The heat-generating body 5 and the heat-insulating cover 6 are relatively moved to remove the heat-insulating cover 6 from the heat-generating body 5 by a mechanism capable of removing and attaching the heat-insulating cover 6 to quickly cool the heat-generating body 5. You can

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a vacuum heat treatment apparatus of the present invention during heating.

FIG. 2 is a diagram showing the structure of the vacuum heat treatment apparatus of the present invention during cooling.

FIG. 3 is a graph showing a difference in input amount during high frequency induction depending on the presence or absence of a heat insulating unit.

[Explanation of symbols]

 1 Vacuum Chamber 2 Vacuum Container 3 Airtight Seal Part 4 High Frequency Induction Heating Coil 5 Heating Element 6 Insulation Cover Part 7 Gas Venting Hole 8 Thermocouple 9 Processing Parts 10 Lifting Table 11 Vacuum Pulling Hole

Claims (2)

[Claims] 1. A heating element for housing a processing component to be heated,
A vacuum container having a vacuum chamber for covering the heating element, an airtight seal portion for preventing air from leaking into the vacuum container, and a high-frequency induction heating coil for heating the heating element in the vacuum container. The vacuum heat treatment apparatus according to claim 1, further comprising a heat insulating cover portion that covers the heating element. 2. The vacuum heat treatment apparatus according to claim 1, further comprising a mechanism for relatively moving the heating element and the heat insulating cover portion to attach and detach the heat insulating cover portion.