JPS6036075B2 - Manufacturing method of sheathed heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a sheathed heater, and in particular, it is an object of the present invention to provide a method for easily making the length of a metal pipe constant.

Generally, when manufacturing a sheathed heater, after filling an insulating material between the metal pipe and the heating wire, rolling is performed to increase the packing density of the insulating material, and then annealing is performed to remove the strain stress of the metal pipe due to rolling. conduct.

Traditionally, this anchoring process was carried out using a sheathed heater in an oxidizing electric field furnace or reducing atmosphere furnace, but this had the disadvantage that it took a long time to heat and also insulating materials other than the metal pipe were heated for a long time. . Further, in the above-mentioned rolling process, the length of the metal pipe may vary from the set value due to irregularities in the outer diameter of the metal pipe before the rolling process or the condition of the rolling mill. For this reason, it is necessary to cut the metal pipe to match the set value, and in this case, a process is required to remove the filler material from the metal/guip end so that the end of the metal pipe can be sealed. It had drawbacks such as.
The present invention eliminates the drawbacks of the conventional sheathed heater manufacturing method described above, and embodiments of the present invention will be described below with reference to the accompanying drawings.

In the figure, 1 is a metal pipe into which a heating wire is inserted, and an insulating material is filled between the metal pipe and the heating wire.

After passing through a rolling process to increase the packing density of the sheath heat outer insulation material, electrodes 2, 2' are connected to both ends of the metal/guipure as shown in FIG.

When a voltage is applied between the electrodes 2 and 2', a current flows through the metal pipe 1 and Joule heat is generated. The metal pipe 1 is heated by this Joule heat and becomes red hot. In this state, remove the electrodes 2 and 2' from the metal/guiboo, and
As shown in the figure, one end of the metal/guipure is fixed with a fixed clamp 3, and the other end is clamped with a movable clamp 4. Furthermore, while this metal pipe is red-hot,
The drive device 5 moves the movable clamp 4 in the longitudinal direction of the metal pipe 1 (in the direction of arrow A). The movable clasp 4 moves until it comes into contact with the stopper 6 and stretches the metal/guipoo. This results in a constant length of the metal/filter. In the above process, the metal pipe is dulled by the Joule heat of the current flowing through the metal pipe 1, so it is carried out in a short time, and the temperature of the insulating material does not become too high. In addition, since the process of drawing the metal pipe 1 is carried out while the metal pipe 1 is in a red-hot state, the hardness is low and the force required for drawing is small, and furthermore, the work hardening caused by this drawing is also reduced. removed. Further, even if the metal pipe 1 is warped due to thermal expansion during the phosphorous annealing process, it becomes straight due to stretching in the red-hot state. In this example, after the electrodes 2 and 2' were removed from the metal/Guipoo, the metal/Guipoo was held between the fixed clamp 3 and the movable clamp 4, but as shown in FIG. , electrodes 2, 2' are connected near both ends of the metal pipe 1, and the metal pipe 1 is held between a fixed clamp 3 and a movable clamp 4 on the outside of the electrodes 2, 2'. The same effect can be obtained by stretching the metal pipe 1 by applying a voltage between the two ends of the metal pipe 1 to make the metal/guipoo red-hot, stopping the voltage application, and driving the driving device 5.

In addition, it is possible to connect the electrodes 2, 2' to any arbitrary position of the metal pipe 1, and it is also possible to locally stretch the metal/guipoo. As is clear from the above description, according to the present invention, the dulling process can be carried out in a short time, thermal deterioration of the insulating material can be prevented, metal/fiber can be easily stretched with a small force, and the metal A constant length can be achieved without causing work hardening of the pipe.

[Brief explanation of the drawing]

FIG. 1 is a front view of one step in a method for producing a sheathed heater showing an embodiment of the present invention, FIG. 2 is a front view of another step in the same method, and FIG. 3 is a front view of another embodiment of the present invention. FIG. 3 is a front view of one step in the method of manufacturing a sheathed heater. 1... Metal pipe, 2, 2'... Electrode, 3... Fixed clamp, 4... Movable clamp, 5... Drive device, 6...stopper. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A heating wire is inserted into a metal pipe, an insulating material is filled between the metal pipe and the heating wire, the metal pipe is rolled, and then a current is passed through the metal pipe, and the metal pipe is heated by generating Joule heat. A method for manufacturing a sheathed heater, comprising annealing the metal pipe and then stretching the metal pipe in the longitudinal direction while the metal pipe is in a red-hot state.