JP2701192B2 - Sheath heater and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheathed heater and a method of manufacturing the same, and more particularly to a sheathed heater swaged (diameter reduced) and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIGS. 15 and 16 show a conventional sheathed heater, in which 1 is a metal pipe made of stainless steel,
Is a core insulator made of magnesia, 3 is a lead pin inserted into a small hole provided eccentrically to the core insulator 2 inside the core insulator 2, 4 is wound around the core insulator 2, and its end is connected to the lead pin 3. The internal heating wire 5 is a heat-resistant insulator such as magnesia filled in a space between the core insulator 2 and the metal pipe 1. Such a sheathed heater is formed by swaging.

In the conventional sheathed heater, as shown in FIGS. 17 and 18 before the swaging step, the end of the internal heating wire 4 is connected to a lead pin by a lead 6 usually formed by an extension of the internal heating wire 4. 3 at the shortest distance. That is, the position between the position A of the outer peripheral surface of the core insulator 2 closest to the lead pin 3 at the eccentric position and the point B extending from this position A in the axial direction of the core insulator 2 and contacting the internal heating wire 4 wound around the core insulator 2 is connected. A flat or inclined groove 8 is formed on the outer peripheral surface of the core insulator 2 along a wire 7, a lead 6 extending from an end of the internal heating wire 4 is extended through the groove 8, and the end is connected to the lead pin 3.
Are inserted into the small holes of the core insulator 2 into which the core insulators 2 are inserted, and are tightened and fixed.

[0004] FIG.
3 shows a wire that is wound around a lead pin 3 instead of being inserted through the small hole and fixed by spot welding.

[0005]

However, when the end of the internal heating wire 4 and the lead pin 3 are connected by the lead 6 at the shortest distance before the swaging process as in the above-mentioned conventional one, the case where the molding is performed by swaging. When the swage ratio, that is, (1− (diameter after swage / diameter before swage)) × 100% is, for example, 14%, the axial length of the core insulator 2 is increased to 1.15 times, and the lead pin 3
And the distance between the end of the internal heating wire 4 and the end of the lead 6
There were many accidents where the cable was excessively stretched and disconnected.

The risk of such a disconnection caused by excessive elongation of the lead 6 due to the swaging is reduced by reducing the swage rate. However, if the swage ratio is reduced, the heat conduction between the internal heat generating wire 4 and the metal pipe 1 via the insulator such as magnesia filled in the metal pipe 1 is reduced, and the heat radiation is deteriorated. Life is shortened. Therefore, it is not preferable to make the swage rate too low.

The present invention has been made to eliminate the above disadvantages.

[0008]

A sheathed heater according to the present invention has a tubular core made of a heat-resistant insulator and fixed to an end face of the core.
Outside the lead pin and the core closest to the lead pin
Wound on a line extending in the axial direction of the core through a point on the circumference
An internal heating wire wound around the outer periphery of the core so that ends come, a lead for connecting the end portion and the lead pin of the internal heating wire, the core and the internal heating wire and the lead and the lead pins and more made assembly The lead comprises an inserted metal pipe and a heat-resistant insulator filled between the metal pipe and the assembly, and the lead extends through a detour that is longer than the shortest distance connecting the lead pin and the end of the internal heating wire. It is characterized by the following.

The lead pin is eccentric with respect to the core.

[0010] manufacturing process of the sheathed heater of the present invention, heat
Closest to the lead pin fixed to the end face of the insulator core
Through a point on the outer peripheral surface of the core in the axial direction of the core.
Winding an internal heating wire wound around the outer periphery of the core so as to finish winding on the extending wire; connecting an end of the internal heating wire to a lead pin through a detour that is not the shortest distance; Swaging after inserting the wire and the lead pin together with the filler into the metal pipe.

In the method of manufacturing the sheathed heater according to the present invention, the lead passing through the bypass is held by the groove or hole formed in the core before the swaging step.

In the method for manufacturing a sheathed heater according to the present invention, the grooves or holes are formed at a plurality of positions displaced in the circumferential direction before the swaging step.

In the method for manufacturing a sheathed heater according to the present invention, the groove has a groove formed on an end face of the core before the swaging step, and a groove formed in an outer circumferential surface of the core in an axial direction. The groove on the end face is bent so that the angle formed between the groove on the outer surface of the core and the groove on the outer surface of the core increases.

In the method of manufacturing the sheathed heater according to the present invention, the lead passing through the bypass is fixed on the outer peripheral surface of the core with an adhesive or a thread before the swaging step.

In the method of manufacturing a sheathed heater according to the present invention, the leads passing through the bypass are guided by pins formed on the end face or the outer peripheral face of the core before the swaging step.

In the method for manufacturing a sheathed heater according to the present invention, the lead passing through the bypass is held by the tubular member fixed to the end face of the core before the swaging step.

In the method of manufacturing the sheathed heater according to the present invention, the lead passing through the bypass passes between the grooves of the E-shaped member fixed to the end face of the core before the swaging step.

In the method for manufacturing a sheathed heater according to the present invention, the detour includes a coil-shaped or zigzag-shaped portion before the swaging step.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

[0020] As in the present invention shown in FIG. 1, Lee
The doping pin 3 is attached to the end face of the cylindrical core insulator 2 made of a heat-resistant insulator.
The lead pin 3 is fixed eccentrically to the core insulator 2.
Through the point on the outer peripheral surface of the core insulator 2 closest to
The internal heating wire 4 is wound around the outer periphery of the core insulator 2 so as to finish winding on the wire, and a detour is formed between a line connecting the end of the internal heating wire 4 and the lead pin 3 with the shortest distance as in the related art. The connection is made by the leads 6 along the line. Therefore, in the present invention, the position C of the outer peripheral surface of the core insulator 2 which does not become the shortest distance with respect to the eccentric lead pin 3, and the internal heating wire 4 extending in the axial direction of the core insulator 2 from this position C and wound around the core insulator 2 A flat or inclined groove 10 extending in the axial direction is formed on the outer peripheral surface of the core insulator 2 along a line 9a connecting the positions D contacting the inner heat generating wires 4 with the leads 6 arranged so as to extend through the groove 10. Between the metal pipe 1 and the above-mentioned assembly, and a heat-resistant insulator 5 is inserted between the metal pipe 1 and the above-mentioned assembly. Swage the whole.

FIG. 2 is a perspective view for explanation showing the paths followed by the leads 6 in the prior art and the present invention before the swaging step. In FIG. 2, 7 'is the lead pin 3.
A line element on the end face of the core insulator 2 connecting the position A and
9b is a line element on the end face of the core insulator 2 connecting the lead pin 3 and the position C, and 9c is a line element connecting the positions A and D on the outer peripheral surface of the core insulator 2.

Since the sheathed heater of the present invention and the method of manufacturing the same are as described above, the length of the lead 6 before swaging is (7 + 7 ') in the conventional one as shown in FIG. In the case of the present invention, (9b + 9a + 9c). As is apparent from FIG. 2, since the lead pin 3 is located eccentrically with respect to the center of the core insulator 2, the wire element 9b
Is longer than the line element 7 ', the line element 9a is equal to 7, and in the case of the present invention, the length of the lead 6 is (9b-7') +
9c = L. When the diameter of the core insulator 2 is reduced by swaging, the lead 6 is extended as described above, but at this time, the groove 10 is broken, and as shown in FIG. The end portion and the lead pin 3 come closer to the position where they are connected at the shortest distance. Even if the axial length of the core insulator 2 is eventually extended by swaging, the lead by swaging by the length close to the above-mentioned length difference L is obtained. The elongation of the lead 6 is alleviated, and the disconnection of the lead 6 can be prevented accordingly.

FIG. 4 shows another embodiment of the present invention in which a through hole 11 is provided in the core insulator 2 instead of the groove 10.

FIG. 5 shows that the lead 6 is moved from the lead pin 3 to the end of the core insulator 2 at the end face of the core insulator 2.
In order to guide the groove 12 to the position C on the outer peripheral surface, a groove 12 connected to the groove 10 is formed, and the groove 12 is bent not in a straight line but in the middle thereof, and is formed on the outer peripheral surface of the core insulator 2. Another embodiment of the present invention in which the angle α formed with the position C is sufficiently obtuse as compared with the case where the groove 12 is linear is shown. According to this embodiment, it is possible to prevent the position C portion on the outer peripheral surface of the core insulator 2 from being damaged at the time of machining the grooves 10 and 12 of the core insulator 2.

FIG. 6 shows that the lead 6 extending along the detour without the grooves 10 and 12 is connected to the core insulator 2.
Another embodiment of the present invention in which an inorganic adhesive 13 is fixed on the outer peripheral surface of the present invention is shown.

FIG. 7 shows that the lead 6 extending along the detour without the grooves 10 and 12 is connected to the core insulator 2.
Another embodiment of the present invention is shown in FIG.

FIG. 8 shows that the lead 6 extending along the detour without the grooves 10 and 12 is attached to the core insulator 2.
Ceramic fixed by embedding etc. on the outer peripheral surface of
Alternatively, another embodiment of the present invention in which the guide is performed by a metal pin 15 is shown.

FIG. 9 shows another embodiment of the present invention in which the ceramic or metal pin 15 in FIG. 8 is formed on the end face of the core insulator 2 instead of the outer peripheral face.

FIG. 10 shows another embodiment of the present invention in which the lead 6 is passed through a ceramic tube 16 fixed to the end face of the core insulator 2 to form a detour.

FIG. 11 shows E fixed to the end face of the core insulator 2.
Another embodiment of the present invention in which a detour is formed by passing a lead 6 through a groove of a ceramic body 17 of a mold is shown.

FIG. 12 shows another embodiment of the present invention in which a plurality of the grooves 10 are provided on the outer peripheral surface of the core insulator 2 in the circumferential direction so as to be spaced apart from each other.

FIG. 13 shows another embodiment of the present invention in which a coil-shaped portion 18 is formed on the lead 6 and this portion is fixed to the core insulator 2 with an adhesive or the like to form a detour.

FIG. 14 shows another embodiment of the present invention in which a zigzag portion 19 is formed on the lead 6 and this portion is fixed to the core insulator 2 with an adhesive or the like to form a detour.

In still another embodiment of the present invention, a coil-shaped portion or a zig-zag-shaped portion of the lead 6 as shown in FIGS. 13 and 14 is formed in a coil-shaped or zig-zag-shaped groove formed in the core insulator 2. Let it be buried and fixed.

In the present invention, the pins 15, the grooves 8,
The shape, number, and position of the through holes 10, 12, and the through holes 11 can be arbitrarily determined in addition to the above embodiment. The present invention can be similarly applied not only to the core insulator 2 having a cylindrical shape but also to a polygonal shape having a triangular or square cross section.

In each of the above embodiments, the lead pin 1
5 is eccentric with respect to the core insulator 2, but the embodiment shown in FIGS. 10 to 14 can be similarly applied to the case where the lead pin 15 is located at the center of the core insulator 2.

[0037]

As described above, according to the sheathed heater of the present invention and the method of manufacturing the same, there is a great advantage that the disconnection of the lead can be prevented even if the swage ratio is increased.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining a sheathed heater of the present invention and a method of manufacturing the same.

FIG. 2 is an explanatory perspective view showing a path followed by a lead between a conventional and a sheathed heater according to the present invention before a swaging step in comparison.

FIG. 3 is an explanatory diagram of a state after swaging of the sheathed heater of the present invention.

FIG. 4 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 5 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 6 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 7 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 8 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 9 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 10 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 11 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 12 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 13 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 14 is an explanatory view of another embodiment of the method of manufacturing the sheathed heater of the present invention.

FIG. 15 is a vertical sectional front view of a conventional sheathed heater.

FIG. 16 is a sectional view taken along line AA of FIG.

FIG. 17 is a cross-sectional view for explaining a method of manufacturing a conventional sheathed heater.

FIG. 18 is a perspective view for explaining a method of manufacturing a conventional sheathed heater.

FIG. 19 is a perspective view for explaining a method of manufacturing a conventional sheathed heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal pipe 2 Core insulator 3 Lead pin 4 Internal heating wire 5 Insulator 6 Lead 7 wire 7 'Wire element 8 Groove 9a Wire element 9b Wire element 9c Wire element 10 Groove 11 Through hole 12 Groove 13 Inorganic adhesive 14 Ceramic thread 15 Pin 16 Ceramic tube 17 Ceramic body 18 Coiled part 19 Zigzag part

Claims (11)

(57) [Claims] 1. A tubular core made of a heat-resistant insulator, a lead pin fixed to an end face of the core, and a wire extending in the axial direction of the core passing through a point on the outer peripheral surface of the core closest to the lead pin. An internal heating wire wound around the outer periphery of the core, a lead connecting the end of the internal heating wire and the lead pin, and an assembly including the core, the internal heating wire, the lead, and the lead pin were inserted. A metal pipe, and a heat-resistant insulator filled between the metal pipe and the assembly, wherein the lead extends through a detour that is longer than the shortest distance connecting the lead pin and the end of the internal heating wire. Characterized sheath heater. 2. The sheathed heater according to claim 1, wherein said lead pin is eccentric with respect to said core. 3. The core is wound around the outer periphery of the core so as to end on a line extending in the axial direction of the core through a point on the outer peripheral surface of the core closest to a lead pin fixed to an end face of the heat-resistant insulating cylindrical core. Winding the internal heating wire, connecting the end of the internal heating wire and the lead pin through a detour that is not the shortest distance, and inserting the internal heating wire and the lead pin together with the filler into the metal pipe. A method of manufacturing a sheathed heater, comprising a step of swaging. 4. The method of manufacturing a sheathed heater according to claim 3, wherein the lead passing through the bypass is held by a groove or a hole formed in the core before the swaging step. Wherein said grooves or holes, swaging step prior claims are formed in a plurality of positions shifted in the circumferential direction 4
A method for manufacturing the sheathed heater described in the above. 6. The groove has a groove formed on an end face of the core before the swaging step and a groove formed in an axial direction on an outer peripheral surface of the core, wherein the groove on the end face and an outer periphery of the core are provided. The method for manufacturing a sheathed heater according to claim 4 or 5, wherein the groove on the end face is bent so that an angle formed between the groove and the groove on the surface is increased. 7. The sheathed heater according to claim 3, wherein a lead passing through the bypass is fixed on an outer peripheral surface of the core with an adhesive or a thread before the swaging step. Method. 8. The lead passing through the bypass is guided by a pin formed on an end surface or an outer peripheral surface of the core before the swaging step.
A method for manufacturing the sheathed heater described in the above. 9. The sheathed heater according to claim 3, wherein the lead passing through the bypass is held by a tubular member fixed to the end face of the core before the swaging step. Production method. 10. The lead according to claim 3, wherein the lead passing through the detour passes between the grooves of the E-shaped member fixed to the end face of the core before the swaging step. Manufacturing method of sheathed heater. 11. The method of claim 3, wherein the detour includes a coiled or zigzag portion before the swaging step.
The method for producing a sheathed heater according to 6, 7, 8, 9 or 10.