JP3975243B2 - Resistance heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resistance heater including a heating element made of a linear electric heating material. Specifically, the present invention relates to an electric resistance heater (hereinafter referred to as “resistance heater”) used as a heating source for industrial heat treatment equipment and the like.
[0002]
[Prior art]
As a conventional resistance heater, a plurality of disk-shaped support insulators having a plurality of through holes formed in the outer peripheral portion and a plurality of U-shaped heating elements are provided. There are known ones in which a linear portion of a U-shaped heating element is inserted into a through hole of each disk-shaped supporting insulator and the insulator and the heating element are fixed by being arranged in series at intervals.
[0003]
[Problems to be solved by the invention]
In the above-described conventional resistance heater, it is necessary to fix the end portions of each heating element to each other by welding or the like on one end side of the plurality of U-shaped heating elements through which the insulator is inserted, which is necessary for the assembly of the resistance heater. There are problems that man-hours increase and the heater becomes expensive. In addition, there is a problem in that when a part of the insulator is broken, it is not possible to replace only the broken insulator, and the entire resistance heater must be exchanged when assembling it in the transportation or heat treatment equipment. Moreover, in the part which the heat generating body penetrated the insulator, since the insulator is located in the outer periphery of a heat generating body, there exists a problem that heat dissipation is bad.
[0004]
An object of the present invention is to provide a resistance heater that solves the above-described problems, is easy to assemble, is inexpensive, can be replaced with an insulator, and has good heat dissipation.
[0005]
[Means for Solving the Problems]
A resistance heater according to the present invention includes a heating coil formed by spirally winding a linear electric heating material, and a plurality of insulators arranged in series on the axis of the heating coil. A disk-shaped base portion having an outer diameter smaller than the inner diameter of the heat generating coil, a plurality of first short-circuit prevention bodies provided at equal intervals in the circumferential direction of the outer peripheral surface of the base portion and projecting outward in the radial direction of the base portion; A second short-circuit prevention body provided at the tip of the prevention body, and the first short-circuit prevention body is orthogonal to the axial direction of the heating coil so as to be parallel to the axial direction of the linear electric heating material of the heating coil. The second short-circuit prevention body is formed in a plate shape that is inclined with respect to the surface to be heated and is positioned between adjacent linear electric heating materials of the heating coil and has a tip projecting outward of the heating coil. It is formed in a plate shape orthogonal to the first short-circuit prevention body, and its axis of the insulator By rotating around, each first short-circuit prevention body can move along the linear electric heating material adjacent to the heating coil, and all the first short-circuit prevention bodies of each insulator The first short-circuit prevention bodies of two adjacent insulators that are arranged at equal intervals in the circumferential direction are shifted in the circumferential direction of the base as viewed from the base axial direction .
[0006]
In the above insulator, it is desirable to coat the outer surface of the second short-circuit prevention body with a highly insulating refractory material.
[0007]
In this resistance heater, it is preferable that the position of each first short-circuit prevention body with respect to the base outer peripheral surface of each insulator is shifted in the base axial direction so as to correspond to the progress of the winding of the linear electric heating material.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
1 and 2 show a resistance heater according to an embodiment of the present invention.
[0010]
The heating element (1) of the resistance heater is formed by winding a metal linear heating material, for example, a nichrome heating material in a spiral shape on the same cylindrical surface in the same direction and alternately at predetermined intervals. Two heating coils (1a) are provided. One end portions of both heat generating coils (1a) are connected to each other by a ring-shaped connecting member (1b), and both heat generating coils (1a) are integrally formed to constitute a double helical heat generating element (1). The other end of each heating coil (1a) is bent along the axial direction, and the other end of the conductor rod-like member (11) extending along the axial direction of the heating element (1) and extending outward in the axial direction. One end is fixed by welding. Further, a plate-like terminal member (5) protruding outward in the radial direction is fixed to the other end of the rod-like member (11) by welding. The terminal member (5) can be connected to a lead wire connected to an appropriate power source.
[0011]
Inside the heating element (1), an insulator (2) having a disk-shaped base (2a) having an outer diameter smaller than the inner diameter of the heating coil (1a) is arranged in series along the axial direction. Yes. The insulator (2) is an integrally fired product, and as shown in FIG. 3, an axial through hole (2b) is formed at the center of the base (2a) of the insulator (2). Four plate-like first short-circuit prevention bodies (2c) projecting radially outward at an angle of 90 ° in the circumferential direction are formed on the outer periphery of the base (2a) of each insulator (2). Yes. A plate-like second short-circuit prevention body (2d) orthogonal to the first short-circuit prevention body (2c) is formed at the tip of each first short-circuit prevention body (2c). Both first short-circuit prevention bodies (2c) are inclined with respect to a plane perpendicular to the axial direction of the heating element (1) so as to be parallel to the axial direction of the linear electric heating material of the heating coil (1a). Further, the first short-circuit prevention body (2c) is provided at a position shifted from each other by 1/4 of the pitch of the heating coil (1a) in the axial direction, and each prevention body (2c) is a wire of the heating coil (1a). It is made to lie between the electric heating materials. Further, the first short-circuit prevention bodies (2c) of the adjacent insulators (2) are arranged so as to form an angle of 45 ° with each other in the same direction or the circumferential direction. The outer periphery of the base (2a) of the insulator (2) and the first and second short-circuit prevention bodies (2c) (2d) are coated with high-purity alumina excellent in insulation even at high temperatures. Moreover, only the outer surface of the second short-circuit prevention body (2d) may be coated.
[0012]
A support insulator (3) having a disc-shaped base (3a) is disposed on one end side of the heating element (1). A protrusion (3b) is formed on the end surface of the base (3a) on the side of the heating element (1), and a gap is formed between one end surface of the heating element (1) and the base (3a) of the support insulator (3). The tip of the protrusion (3b) is positioned inside the heating element (1), and the tip of the protrusion (3b) is positioned at the end of the support lever (3) side. It is in contact with one end surface. The diameter of the protrusion (3b) is smaller than the inner diameter of the heating coil (1a), and the tip of the heating element (1) is spaced from the outer periphery of the protrusion (3) around the protrusion (3a). It is designed to be open. A single axial through hole (3c) is formed at the center of the support insulator (3), and a recess (3d) is formed at one end face of the support insulator (3). The outer periphery of the insulator (3) is coated with high-purity alumina.
[0013]
On the other hand, a disc-shaped support insulator (4) having the same outer diameter as the base (3a) of the support insulator (3) is disposed on the other end side of the heating element (1). One axial through hole (4a) is formed in the center of the support insulator (4), and two axial through holes (4b) are formed in the outer periphery of the support insulator (4). The rod-like member (11) of (1) is inserted through the through hole (4b). In addition, a slit (4c) extending from the through hole (4b) to the outer periphery of the insulator (4) toward the outer periphery in the radial direction is formed in the through hole (4b) on the outer periphery of the support insulator (4). The terminal member (5) passes through the slit (4c) when the rod-like member (11) is inserted into the through hole (4b). The outer periphery of the support insulator (4) is coated with high-purity alumina.
[0014]
The through holes (2b), (3c), and (4a) formed in the center of each insulator (2), (3), and (4) are in communication with each other, and the through holes (2b), (3c), and (4a) A rod-like heating element fixing member (6) is inserted through the end. One end of the heating element fixing member (6) is located in the recess (3d) of the support insulator (3) and does not protrude from the support insulator (3), and the other end protrudes from the support insulator (4). The fixing member (6) is provided with male threads on both ends, and nuts (7) are fastened to the male threads to secure the heating element (1) and each insulator (2 ) (3) (4) are integrated. The fixing member (6) has an axial through hole (6a).
[0015]
The integrated heating element (1) and each insulator (2), (3), (4) are supported in a support insulator (3) in a radiant tube (9) made of, for example, heat-resistant steel with one end closed and the other end opened. ) Is positioned on the closing side, and the terminal member (5) is inserted so as to be positioned outside the radiant tube (9). At this time, the second short-circuit prevention body (2d) is located between the outer periphery of the heating element (1) and the inner periphery of the radiant tube (9).
[0016]
In the resistance heater configured as described above, for example, when one of the support insulators (3) and (4) on both sides is damaged, the nut (7) located on each side is loosened to cause damage. After the removed insulators (3) and (4) are removed from the heating element fixing member (6) and replaced with new insulators (3) and (4), the nut (7) may be tightened. When the support insulator (4) is replaced, the terminal member (5) passes through the slit (4c), so that the terminal member (5) and the insulator (4) do not interfere with each other.
[0017]
Also, if one or more of the insulators (2) arranged in series are damaged, loosen the nut (7) on the support insulator (4) side and attach the support insulator (4) to the heating element fixing member (6) After removing from the coil, rotate the insulator (2) to move the first short-circuit prevention member (2c) along the winding direction of the heating coil (1a), and place the insulator (2) on the other end of the heating coil (1a). Remove the broken insulator (2) from the inside of the heating coil (1a) in order from the insulator (2) located at the other end and replace the damaged insulator (2) with a new insulator (2). In order from the end side, the removed insulator (2) and the replaced insulator (2) are rotated to move the first short-circuit prevention member (2c) along the winding direction of the heating coil (1a), and the insulator (2) is moved. The heat generating coil (1a) is positioned at a predetermined position, the heat generating element fixing member (6) is inserted into the support insulator (4), and the nut (7) is tightened.
[0018]
When the above resistance heater is used in a heat treatment facility or the like, if an inert gas is blown from the other end opening of the through hole (6a) of the heating element fixing member (6), the inert gas is introduced into the tube (9). It spreads all over and can prevent excessive oxidation of the heating element (1).
[0019]
In addition, even if the heating element (1) is thermally expanded when the resistance heater is used, the heating element (1) can be expanded between one end surface of the heating element (1) and the base (3a) of the supporting insulator (3) and inside the heating element (1). And an outer periphery of the base (3a), the extension due to thermal expansion can be absorbed, and the heating coil (1a) can be freely expanded.
[0020]
FIG. 4 shows another insulator (12) used in the resistance heater of the present invention. The insulator (12) shown in the figure is 180 ° in the circumferential direction from the axial through hole (12b) formed in the center of the cylindrical base (12a) and the outer peripheral surface of the base (12a). Two plate-like first short-circuit prevention bodies (12c) projecting radially outward at an angle of the angle, and a first short-circuit prevention body (12c) formed at the tip of each first short-circuit prevention body (12c) ) And a plate-like second short-circuit prevention body (12d) orthogonal thereto. Both first short-circuit prevention bodies (12c) are inclined with respect to a plane perpendicular to the axial direction so as to be parallel to the axial direction of the linear electric heating material of the heating coil (1a), and the heating coils in the axial direction. It is provided at a position shifted by a half of the pitch of (1a), and is positioned between the linear electric heating materials of the heating coil (1a). The outer periphery of the insulator (12) and the first and second short-circuit prevention bodies (12c) (12d) are coated with high-purity alumina.
[0021]
FIG. 5 shows a resistance heater according to a second embodiment of the present invention. In the following description, the same components and parts as those shown in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In this resistance heater, an L-shaped terminal member (15) is used. The terminal member (15) includes a mounting portion parallel to the axis and a terminal portion protruding radially outward. The mounting portion is welded to the rod-shaped member (11), and both the terminal members (15) The terminal portions are arranged to make 180 ° in the circumferential direction. One axial through hole (14a) is formed in the central portion of the support insulator (14), and two axial through holes (14b) long in the circumferential direction are formed in the outer peripheral portion. Further, cutouts (14c) extending outward from the circumferential through holes (14b) at an angle of 180 ° in the circumferential direction are formed.
[0022]
In the above resistance heater, after removing the nut (7), the lever (14) is rotated to align the positions of the notch (14c) and the terminal member (15), and then the lever (14) is removed.
[0023]
In the above resistance heater, after removing the nut (7), the lever (24) is rotated to align the positions of the notch (24c) and the terminal member (25), and then the lever (24) is removed.
[0024]
In addition, the number of the 1st short circuit prevention bodies which protrude from the base part of an insulator is not restricted to 2 or 4 like the said embodiment, Five or more may be sufficient.
[0025]
【The invention's effect】
In the resistance heater of the present invention, there is no need to fix each insulator and the heating element to each other, the number of steps required for assembling the resistance heater can be reduced, and the heater becomes inexpensive. Moreover, since the 1st short circuit prevention body is located between the linear heating materials of a heat generating body, the heating materials of a helical heating body do not short-circuit. Furthermore, since the second short-circuit prevention body is located between the tube and the heating element, the tube and the heating element do not contact and short-circuit. When the insulator is damaged, the insulator is rotated in order from the insulator located at the end and moved in the axial direction to take out the insulator from the end of the heating element, and replace the damaged insulator. Thereafter, the insulator is inserted in order from the end of the heating coil, and the insulator is rotated to be positioned at a predetermined location. Furthermore, since the insulator does not cover the periphery of the heating element, heat dissipation is good.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a resistance heater according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the resistance heater.
FIG. 3 is a perspective view of an insulator used for the resistance heater.
FIG. 4 is a perspective view of another insulator used in the resistance heater.
FIG. 5 is an exploded perspective view of a resistance heater according to a second embodiment of the present invention.
[Explanation of symbols]
(1) Heating element
(1a) Heating coil
(2) (12) Choshi
(2c) (12c) First short-circuit prevention body
( 2d) (12d) Second short-circuit prevention body

Claims (3)

  A heating coil formed by spirally winding a linear electric heating material, and a plurality of insulators arranged in series on the axis of the heating coil, each insulator having an outer diameter smaller than the inner diameter of the heating coil And a plurality of first short-circuit prevention bodies provided at equal intervals in the circumferential direction of the base outer peripheral surface and projecting outward in the radial direction of the base, and provided at the tips of the first short-circuit prevention bodies. The first short circuit prevention body is inclined with respect to a plane orthogonal to the axial direction of the heating coil so as to be parallel to the axial direction of the linear heating material of the heating coil, and It is located between the adjacent linear electric heating materials of the heating coil and is formed in a plate shape with the tip protruding outward from the heating coil, and the second short circuit prevention body is orthogonal to the first short circuit prevention body. It is formed in a plate shape, and each first short circuit is caused by the rotation of the insulator around its axis. The stationary body can be moved along the linear electric heating material adjacent to the heating coil, and all the first short-circuit prevention bodies of the respective insulators are arranged at equal intervals in the base circumferential direction. The resistance heater which the 1st short circuit prevention body of two adjacent insulators has shifted | deviated to the base peripheral direction seeing from the base axial direction. The resistance heater according to claim 1, wherein the outer surface of the second short-circuit prevention body is coated with a highly insulating fire-resistant material.   3. The resistance heating according to claim 1, wherein each position of the first short-circuit prevention body with respect to the base outer peripheral surface of each insulator is shifted in the base axial direction so as to correspond to the progress of the winding of the linear electric heating material. heater.

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