JPH0357038Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a heating element that is attached to an arbitrary member to be attached and installed in water etc. in order to heat water etc. This invention relates to a heating element that can avoid physical damage.

[Conventional technology]

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

FIG. 2 shows a sheathed heater 1 according to the prior art.
It shows a state where it is attached to a flange F as a member to be attached.

2 is a metal pipe made of stainless steel bent into a U-shape, and inside the metal pipe 2 is a heating coil 3.
is installed. Takeout terminals 4, 4 are attached to both ends of the heating coil 3, and these takeout terminals 4, 4 slightly protrude outward from both ends of the metal pipe 2. Therefore, current can be supplied to the heat generating coil 3 through the lead terminals 4, 4, thereby causing the heat generating coil 3 to generate heat.

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 up to a length l from both end surfaces of the metal pipe 2.
Both ends are closed with sealing materials 6, 6 having a length l. Here, each sealing material 6 is formed with an insertion hole through which each of the extraction terminals 4 is inserted.

The sheathed heater 1 is roughly constituted by the metal pipe 2, heating coil 3, take-out terminals 4, 4, and sealing materials 6, 6.

Next, the formation of the sheathed heater 1 will be explained. First, after connecting the heating coil 3 and the extraction terminal 4, they are inserted into the metal pipe 2. After that, the metal pipe 2 is filled with magnesia powder 5. Thereafter, the end opening of the metal pipe 2 is temporarily closed with a rubber stopper G (shown in FIG. 3). Afterwards,
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 l of the metal pipe 2 is the dimension in which the rubber stopper G used during the processing process was fitted, and is a space. This sheathed heater 1 is inserted into the hole 7b of the constricted part 7a provided on the flange F, and set at a position L from the end of the metal pipe 2. In this state, the constricted portion 7 of the flange F
A 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 no gaps are formed in order to prevent gap corrosion. On the other hand, the dimension l of the space of the metal pipe 2 is usually 5 to 10
Generally, the diameter is in the range of mm, and if it exceeds 10 mm, there is a risk that the rubber plug G may not be able to be removed after diameter reduction processing. or,
Removing the magnesia powder 5 after the diameter reduction process has problems, such as the fact that the magnesia powder is hard and compressed, so it is difficult to remove it deeply, and the cutting tool is severely worn out. The dimension L between the end of the metal pipe 2 and the flange F is generally 10 mm or more, and the reason for this is to keep the temperature of the sealing material 6 as low as possible during use. Therefore, the welding part Y is always connected to the part of the metal pipe 2 filled with the magnesia powder 5.

[Problem that the invention attempts 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 the magnesia powder 5 is a highly hygroscopic substance, it readily absorbs 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 large, the moisture will break through the metal pipe 2, whose strength has been reduced due to welding heat, and be released to the outside.
There will be a hole in it, resulting in a defect. For this reason, there is a problem that the magnesia powder 5 of the sheathed heater 1 must be thoroughly dried before welding, and welding must be performed without absorbing moisture, resulting in extremely poor workability.

Therefore, the object of the present invention has been made in view of the above-mentioned circumstances, and the object is to provide a heating element that does not create holes in the pipe during removal and has stable quality.

[Means for solving problems]

In the present invention, the outer periphery of the tip of the pipe into which the sealing material is fitted is used as a thermal joint, and the hole in the attached member is made into a throttle hole, with the throttle part facing the bottom of the pipe.

[Effect]

Since the insulating powder is not close to the thermal joint, even if moisture is adsorbed on the insulating powder, the moisture will not evaporate and therefore will not break through the pipe.
In addition, since the constricted portion faces the bottom of the pipe, it looks good and does not cause injury when handled.

〔Example〕

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

The feature of the present invention is that a welded portion Y is provided on the outer circumferential surface of both ends of the metal pipe 2, that is, on the outer circumferential surface of the metal pipe 2 where the sealing materials 6, 6 are located, and this welded portion (thermal joint) Y is connected to the throttle hole. 7b and welded it. Therefore, there is no powdered magnesia 5 in the vicinity of the welded portion Y, and the magnesia powder 5
This is an unfilled interval.

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

First, both ends of the sheathed heater 1 are inserted into the throttle hole 7b of the flange F, and set so that both end surfaces of the metal pipe 2 and the flange F are substantially flush with each other. However, the cylindrical constricted portion 7a is set so as to face the bottom of the pipe 2. Thereafter, the constricted portion 7a of the flange F and the metal pipe 2 are fixed together by a welded portion Y by electric arc welding.

Therefore, in the present invention, the welded part Y does not come close to the magnesia powder 5, and therefore, even if the magnesia powder 5 adsorbs moisture, the moisture is evaporated by the heat from the welded part Y. Therefore, unlike the prior art, the metal pipe 2 is not damaged by the evaporation pressure at that time.

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

[Effect of idea]

As explained above, according to the present invention, insulating powder such as magnesia powder is not filled in the inside of the pipe and in the vicinity of the thermal joint, so that the moisture in the insulating powder is There is no evaporation due to the thermal influence from the thermal joint, and therefore, the problem of the pipe being thermally damaged due to the evaporation pressure of moisture, as in the prior art, is avoided. In addition, since the constricted portion 7a faces the bottom of the pipe, the surface of the flange F becomes flat, so there is no risk of injury to hands etc. during handling, and the appearance can be improved.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a sheathed heater according to the present invention attached to a member to be attached, Fig. 2 is a side sectional view of a conventional sheathed heater attached to a member to be attached, and Fig. 3 is a side sectional view of a sheathed heater according to the present invention attached to a member to be attached. FIG. 3 is a side sectional view showing the heater in the middle of being molded. 1... Sheathed heater (heating element), 2... Metal pipe (pipe), 3... Heat generating coil, 5... Magnesia powder (insulating powder), Y... Welding part (thermal joint).

Claims (1)

[Scope of utility model registration request] A U-shaped pipe, a heating coil provided in the pipe, an insulating powder filled in the pipe to electrically insulate between the heating coil and the pipe, and an insulating powder at both ends of the pipe. The outer circumferential surface of the pipe corresponding to the sealing material is inserted into a hole in a flat plate-shaped member to be attached as a thermal joint, and the hole is connected to a cylindrical constricted part. The aperture hole has a U
A heating element characterized by having a letter-shaped pipe facing toward the bottom.