JP2777413B2 - Heat shield - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat shielding device, and more particularly, to an improvement that enhances a heat shielding effect by reflecting a heat ray.

<Conventional Technology> Various heating devices (hereinafter, heating devices) such as a resistance heating device, an infrared heating device, and an induction heating device use various types of heat shielding devices. This is because heat generation energy is confined inside the heating device, leakage to the outside is prevented, and thermal efficiency is increased. In particular, in a high-temperature heating device of several hundred degrees C. to several thousand degrees C., a heat shielding device for shielding heat rays is indispensable.

In general, a heat shield device firstly has a reflection function of reflecting a heat ray and returning it to the inside of the heating device, secondly, a heat ray cut-off function of blocking a heat ray and not leaking outside, and thirdly, a radiation device. It is desired to have a radiation function of radiating a heat ray toward the inside of the heating device even when the device is heated.

For this reason, conventionally, the heat shield device has been configured by using a high melting point metal material such as molybdenum or tantalum, which is rich in reflection function, and superimposing multiple thin plates or meshes of these metals.

Hereinafter, the structure of a typical conventional heat shield device will be described with reference to FIG. FIG. 5 is a partially cutaway perspective view showing the configuration of the internal heat type vacuum furnace.

A cylindrical heating element 91 is provided inside the vacuum furnace 9,
Outside that, a heat shield 93 is arranged. Heat shield
Reference numeral 93 denotes a concentric cylindrical body in which molybdenum cylinders having a thickness of about 0.2 mm are multiplexed. The sample to be heated 92 is a heating element 91.
It is housed in the center.

The heat rays radiated outward from the heating element 91 are reflected by the heat shield 93 and returned to the heating element 91. As a result, since the radiation loss is reduced, the heating element 91 is heated to a high temperature with small electric power.

The performance of the heat shield device directly affects the performance of the heating device, particularly, the heating temperature, the thermal efficiency, and the temperature distribution.

<Problems to be solved by the invention> However, according to the above-described conventional technology, the heat shield device is deformed due to thermal expansion or contraction, and the heat shield function is deteriorated. In general, at a high temperature of 1000 ° C. or higher, the refractory metal is transformed and crystallized, and the reflection function of the heat shield decreases. In addition, the high melting point metal becomes brittle at high temperatures, and the heat shield device is easily damaged.

On the other hand, the heat shield device is made of graphite or
It can be made of carbon, but these carbon materials are brittle and cannot be thinned. For this reason, there is a disadvantage that the heat shield device becomes large and heavy, and the heat transfer loss via the support structure increases.

In addition, various heat insulating materials (mats) such as felt-like carbon fibers and cotton-like ceramics can be used instead of metals and carbon materials, but the heat-ray reflecting function is low, and the performance of the heat shield device is poor. Become.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the unsolved problems of the prior art and to provide a small and lightweight heat shield device that withstands high temperatures and reflects heat rays.

<Means for Solving the Problems> In order to achieve the above object, the present invention is a heat shield device including a cylindrical body, a top plate, and a bottom plate that cover a heating element. A surface layer that reflects a heat ray from the heating element on a heat shielding surface of the innermost carbonaceous material of the cylindrical body, the top plate, and the bottom plate, while laminating a plurality of carbonaceous materials including carbon fibers. Is formed.

<Operation> According to the configuration of the present invention, in the carbonaceous material containing carbon fibers, the carbon fibers mechanically reinforce the heat shielding surface, and the carbon fibers and / or carbonaceous material is formed without being thermally deformed. It functions to stably reflect the heat rays by maintaining the shape of the heat shield surface at a predetermined value even at high temperatures.

In addition, the carbonaceous material containing carbon fibers has anisotropy of heat conduction depending on the orientation direction of the carbon fibers, and acts to reduce heat conduction in a direction perpendicular to the fiber axis as compared with the carbon fiber axis direction. Eggplant

Moreover, the carbonaceous material containing carbon fibers facilitates the formation of the surface layer due to the anchor effect.

Embodiments Hereinafter, some embodiments of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a cross-sectional view of the vacuum furnace 9 as viewed from the side, and shows the configuration of a heat shield device according to a first embodiment of the present invention.
A cylindrical heating element 1 having a diameter of about 50 mm and a height of about 100 mm is provided inside the vacuum furnace 9, and a heat shield device 3 that covers the heating element 1 is attached outside the heating element 1. I have.

In this embodiment, the heating element 1 and the heat shield 3 are formed of a carbon fiber / carbon composite material (hereinafter, C / C), which is an example of a carbonaceous material containing carbon fibers, and have a C / C carbon content. The fiber axis is oriented parallel to each surface to suppress thermal expansion in the in-plane direction and to reduce heat conduction in a direction perpendicular to the heat shield surface.

The heating element 1 is formed in a substantially rectangular liquid by cutting a slit into a cylindrical surface having a thickness of about 1 mm. An electrode 2 is connected to an end of the heating element 1 so that a heating current is supplied from outside the vacuum furnace 9. Is supplied.

The heat shield device 3 is a triple tea caddy formed by C / C having a plate thickness of about 0.3 mm, and each surface of the tea caddy forms a radiation surface. Holes 21 for connecting the heating element 1 to the electrodes 2 are formed at two places on the bottom surface of the heat shield device 3. And
The innermost cylinder 31a is placed on a bottom plate 31b having a diameter slightly larger than its outer diameter, and the bottom plate 31b is placed on the cylinder 31a.
A top plate 31c having the same diameter as that of the top plate 31c is placed. The outside of the innermost layer of the heat shield device 3 thus configured is covered with a second layer (32a, 32b, 32c) slightly larger than the innermost layer and having the same configuration as the innermost layer. , The third layer (33a, 33b, 33
c) is covered with. Each of these cylinders (31a, 32
a, 33a), the space between the bottom plates (31b, 32b, 33b), and the space between the top plates (31c, 32c, 33c) each have a gap of 1 mm, and furthermore, each cylinder (31a, 32a) , 33a) are covered by each bottom plate (31b, 32b, 33b) and each top plate (31c, 32c, 33c), so that heat rays do not leak from the heat shield device 3 to the outside.

According to the configuration of this embodiment, the inside of the vacuum furnace 9 is evacuated to vacuum, and heating power is injected into the heating element 1. The heat shield surface of the heat shield device 3, particularly the inner surface of the innermost cylinder 31a, reflects the heat rays radiated outward by the heating element 1 and returns the heat ray to the heating element 1.
Non-reflected heat rays are absorbed and blocked by the cylinder 31a. The cylinder 31a absorbs and heats the heat rays, and the cylinder 31a returns the heat rays corresponding to the temperature to the inside of the cylinder 31a. In addition, each heat-shielding surface of the heat-shielding device 3 reflects a heat ray similarly to the cylinder 31a of the innermost layer, and blocks the heat ray from leaking outside.

According to the structure of this embodiment, since the C / C used for the heating element and the heat shield device is lightweight and has a small specific heat, there is an effect that the temperature of the heating device can be rapidly raised and cooled. Also,
Since both the heating element 1 and the heat shield device 3 are formed of carbonaceous material, the heating device can also heat to a high temperature of 2000 ° C. or more.
The heating element 1 was heated to 1800 ° C. by injecting 1.5 KW of power into the heating element 1. At this time, the innermost cylinder 31a of the heat shield device 3 is at about 1000 ° C., and the innermost cylinder 33a is at 500 ° C.
° C.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a sectional view of the vacuum furnace 9 as viewed from the side. The configuration of the second embodiment differs from the configuration of the first embodiment in that the heat shield device 3 made of C / C is covered by a second heat shield device 4 and the second heat shield device 4 is provided. The heat device 4 is characterized in that it is formed in a triple cylindrical shape by a stainless thin plate having a thickness of about 0.2 mm. Note that the upper (top) surface and the lower (bottom) surface of the second heat shield device 4 are each covered with a triple top plate 4c and a bottom plate 4b. A hole 22 for connecting the heating element 1 to the electrode 2 is formed in the bottom plate 4b.

According to the configuration of the second embodiment, the second heat shield device 4
The temperature of the innermost layer is about 300 ° C., and the stainless steel is not thermally deformed or deteriorated. Further, since the heating element 1 is covered by the heat shield device 3 and the second heat shield device 4,
When the heating element 1 is heated to 1800 ° C., the second heat shield 4
The outside temperature is about 70 ° C, and the side wall temperature of the vacuum furnace 9 is 50 ° C
Degree, and the operator does not get burned. Further, the heating element 1 and the heat shield device 3 have the effect of reducing the surface of stainless steel by the inherent reducing action of carbonaceous material and maintaining the luster inherent to metal.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory view in which a part of a structure constituting a heat shield device by combining flat C / C thin plates is omitted and shown. The C / C thin plate 35 has claw-shaped protrusions 35a at both upper and lower ends.
have. These projections 35a are inserted into slits 41s formed in the innermost cylinder 41 made of stainless steel forming the second heat shield device 4, and as a result, the plurality of C / C thin plates 35 are It is locked along the inner surface of the heat shield 4 to form a circumferential heat shield 3.

According to the configuration of the third embodiment, the heat shield device 3 having a desired shape and size can be formed by combining the C / C thin plate 35 having a simple shape, and the C / C thin plate 35 and the second heat shield device can be formed. 4 has a point (line) contact, which has the effect of reducing heat loss due to heat conduction. Further, even when the second heat shield device 4 is thermally deformed, the C / C thin plate 35 inserted into the slit can be flexibly coped with and is not damaged. Moreover, the C / C thin plate 3 of the heat shield device 3
5 can be easily replaced.

Next, a configuration of a fourth embodiment of the present invention will be described with reference to FIG. 4 (A) and 4 (B) are cross-sectional views showing another configuration of the carbonaceous material containing carbon fibers used in the present invention.

FIG. 5A shows a heat shield device formed by embedding carbon fibers 5 in a carbonaceous binder 51 and performing heat treatment. As the binder 51, a paste-like mixture of furfuryl alcohol and carbon powder was used. As the carbon fiber 5, a PAN-based carbon fiber having a fiber diameter of about 7 microns was used. In the heat treatment, after curing at 150 ° C. for 16 hours, it was heated to 500 ° C. in a vacuum. The surface of the cured material was polished to form a heat shield surface 52.

According to the configuration of this embodiment, the heat shield device 52 having a complicated curved surface can be easily formed, and the heat shield device is supported by the carbon fiber 5 extending from the edge. It can be fixed to a member or the like.

FIG. 2B shows a heat shield device in which a metal layer 61 is formed on one surface of the C / C flat plate 6. Stainless steel (SUS316) was used as the metal. First, a stainless steel plate having a thickness of 0.3 mm was placed on the C / C flat plate 6, heated to 1200 ° C. in a vacuum, and then cooled. As a result, a stainless steel layer 61 adhered to one side of the C / C plate 6 was formed, and the surface of the stainless steel layer 61 was polished to obtain a glossy heat shielding surface 62.

According to the configuration of this embodiment, the surface of the C / C plate 6 also has a so-called anchor effect of micro unevenness, and is welded to the stainless steel plate 61 to form a strong heat shielding surface 62. as a result,
A heat shield device that efficiently reflects heat rays can be provided.

Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the shape of the heat shield device should be a polyhedron shape, or the metal layer formed on the C / C plate should be an oxide layer or a nitride layer, or a pyrolytic graphite layer, an amorphous carbon layer, a diamond layer, etc. Alternatively, they can be laminated in multiple layers.

<Effects of the Invention> According to the present invention, since the heat shield device is formed by the carbonaceous material including the carbon fiber, the heat ray reflection function does not decrease even at a high temperature. In addition, since the entire periphery of the heating element is covered by the heat shield device, heat rays from the heating element do not leak to the outside. Further, since the surface layer for heat reflection is formed on the innermost layer of the heat shield device, leakage of heat rays to the outside can be more effectively prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of the first embodiment of the present invention, FIG. 2 is a sectional view showing the structure of the second embodiment, and FIG.
FIGS. 4A and 4B are explanatory views showing the configuration of the third embodiment, and FIGS. 4A and 4B are cross-sectional views showing the configuration of the fourth embodiment.
FIG. 5 is a perspective view for explaining the prior art. 1 ... heating element, 3, 4 ... heat shield device, 52, 62 ... heat shield surface

Claims (1)

(57) [Claims] 1. A heat shield device comprising a cylindrical body, a top plate, and a bottom plate covering a heating element, wherein the cylindrical body, the top plate, and the bottom plate are formed in layers by stacking a plurality of carbonaceous materials including carbon fibers. A heat shield device, wherein a surface layer that reflects heat rays from the heating element is formed on the innermost heat shield surface of the carbonaceous material of the cylindrical body, the top plate, and the bottom plate.