JPS6276278A - Sheathed heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sheathed heater that is attached to an arbitrary attached member and installed in water etc. for heating water etc., and particularly relates to a sheathed heater that is installed in water etc. for heating water etc. The present invention relates to a sheathed heater that can avoid thermal damage in some cases.

[Conventional technology]

-a, a sheathed heater is known as a heating element for heating water or the like.

FIG. 2 shows the state after the sheathed heater 1 and the flange F as the attached member are attached according to the prior art.
Reference numeral 2 denotes a metal pipe made of stainless steel bent into a U-shape, and a heating coil 3 is disposed within the metal pipe 2.

Takeout terminals 4, 4 are attached to both ends of the heating coil 3, and these takeout terminals 4, 4 protrude outward from both ends of the metal pipe 2.

The metal pipe 2 is filled with magnesia powder 5 as an insulating powder that insulates between the metal pipe 2 and the heating coil 3.

The magnesia powder 5 is filled from both end faces of the metal pipe 20 except for a predetermined length l, and both ends of the metal pipe 2 are closed with a sealing material 6.6 having a length l. .

Here, each sealing material 6 is formed with an insertion hole through which each of the above-mentioned lead-out terminals 4, 4 is pushed. The sheathed heater 1 is roughly constituted by the metal pipe 2, heating coil 3, lead terminals 4, 4, and sealing material 6.6.

Next, the manufacturing procedure of the sheathed heater 1 will be explained.

First, the extraction terminals 4, 4 are connected to both ends of the heating coil 3, and then these are inserted into the metal pipe 2.

After that, the metal pipe 2 is filled with magnesia powder 5. After that, the end opening of the metal pipe 2 is connected to the rubber stopper G (the third
(shown in the figure) for temporary occlusion. Thereafter, the outer diameter of the metal pipe 2 is reduced. This state is shown in FIG.

Next, the rubber stopper G is removed, and the metal pipe 2, which has been work-hardened by the diameter reduction process, is heat-treated to soften it. After the heat treatment, the sheathed heater 1 shown in FIG. 2 is obtained by bending it into a U-shape.

The end dimension I of the metal pipe 2 is the dimension in which the rubber stopper G used during the processing process was fitted, and it is a space, so after sealing it by pushing the sealing material 6 into this space,
A constriction part 7 provided on the flange F of this sheathed heater 1
Insert it into the hole 7b of the metal pipe 2, and set it at a position L from the end of the metal pipe 2. In this state, the constricted portion 7a of the flange F and the metal pipe 2 are welded by arc welding to form a welded portion Y as a thermal joint, thereby fixing the two. In the case of water heating, this welding part Y is generally welded from the side that enters the water so that the gap A is not formed to prevent gap corrosion.

On the other hand, the dimension l of the space part of the metal pipe 2 is usually 5 to 10 m.
gm is generally in the range of 1.0 m or more, there is a risk that the rubber stopper G will not come out after the diameter reduction process.

Also, removing the magnetic screw 1 powder 5 after diameter reduction processing is as follows:
Since the magnesia powder 5 is hard and compressed, it is difficult to remove it deeply and there are problems such as severe wear of the cutting tool.

Furthermore, the dimension between the end face of the metal pipe 2 and the flange F is generally set to 1Om or more, and the reason for this is to prevent the sealing material 6 from being affected by temperature during welding as much as possible. Therefore, the welding portion Y was always performed on the outer circumferential surface of the metal pipe 2 in the portion filled with the magnesia powder 5.

[Problem that the invention seeks to solve]

As described above, in the welding portion Y between this type of sheathed heater 1 and the flange F according to the prior art, the metal pipe 2 is filled with magnesia powder 5.

By the way, since magnesia powder 5 is an extremely hygroscopic substance, it readily adsorbs moisture in the air.

Therefore, when welding something in such a state, the moisture absorbed by the heat will rapidly vaporize and expand in volume, and as a result, some of it will be released to the outside from the opening of the metal pipe 2, but the degree of adsorption will be limited. If the moisture is too strong, the moisture will break through the metal pipe 2, whose strength is lower than that of the welding heat, and will be released to the outside, creating a hole in the metal pipe 2 and causing it to become defective.

Therefore, before welding, the magnesia powder 5 of the sheathed heater 1
There were problems such as the need to thoroughly dry the material and weld it before it absorbed moisture, resulting in extremely poor workability.

This invention was made in view of the above circumstances, and its purpose is to provide a sheathed heater with stable quality that does not cause holes in metal pipes during installation.

[Means for solving problems]

The present invention provides an unfilled section with insulating powder at the end of a metal pipe, and after thermally joining a member to be attached such as welding or brazing on the outer peripheral surface of the metal pipe in the unfilled section, the pipe is The unfilled section is filled with insulating powder, and then the end opening is sealed with a sealing material.

[Function] In the sheathed heater of the present invention, when thermally bonding the metal pipe and the attached member, the insulating powder is not filled into the thermal bonding part, so even if moisture is adsorbed to the insulating powder, The water does not evaporate and therefore does not penetrate the metal pipe and create a hole.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

A feature of the present invention is that when welding the metal pipe 2 and the flange F, welding is performed in such a manner that no magnesia powder 5 is present in the welded portion Y.

Next, a procedure for attaching the sheathed heater 1 to the flange F will be explained.

First, insert both ends of the sheathed heater 1 into the hole b of the 7-lunge F, and connect both end surfaces of the metal pipe 2 and the flange F to the road surface.
Set it so that

Thereafter, the constricted portion 7a of the flange F and the metal pipe 2 are fixed together by electric arc welding.

Therefore, in the present invention, the inner end portion of the metal pipe 2 corresponding to the welded portion Y is not filled with magnesia powder 5, and therefore, even though the magnesia powder 5 adsorbs moisture,
The moisture does not evaporate and expand due to the heat from the welding part Y, and therefore, the metal pipe 2 at the welding part Y is not damaged due to the evaporation pressure at that time and has holes. Never.

After welding is completed, the metal pipe 2 is supplemented with 17gnesia powder 8, and finally the end opening is sealed with a sealing material 6.

In the above embodiment, a welded portion is used as a thermal joint, but the same applies to a brazed portion.

〔Effect of the invention〕

As explained above, according to the present invention, when a member to be attached is attached to the end of a metal pipe by thermal bonding, the insulating powder in the metal pipe corresponding to the bonding area is filled after the thermal bonding is performed. As a result, the moisture in the insulating powder does not evaporate due to the thermal influence from the thermal joint, and therefore the thermal joint of the metal pipe is damaged by the evaporation pressure of the moisture. The wR problem can be avoided.

[Brief explanation of drawings]

Fig. 1 is a sectional side view of a sheathed heater according to the present invention attached to a member to be attached, Fig. 2 is a sectional side view of a conventional sheathed heater attached to a member to be attached, and Fig. 3 is a sectional side view of a sheathed heater according to the present invention attached to a member to be attached. It is a side sectional view showing diameter reduction processing of a heater. In the figure, 1 is a sheathed heater, 2 is a metal pipe, 3 is a heating coil, 5 is magnesia powder, 6 is a sealing material, and Y is a welded part (
thermal junction). Agent Masuo Oiwa (2 others) Figure 3

Claims (1)

[Claims] A sheathed heater is constructed of a metal pipe, a heating coil provided in the metal pipe, and insulating powder filled between the heating coil and the metal pipe. After providing an unfilled section that is not filled and joining a member to be attached on the outer peripheral surface of the pipe in the unfilled section by thermal joining means such as welding or brazing, insulating powder is applied to the unfilled section of the metal pipe. A sheathed heater made by filling the required amount and then sealing the end opening with a sealing material.