JPH0147872B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pipe heater, the purpose of which is to make the insulating powder contained inside the pipe heater non-hygroscopic and to obtain high insulation properties.

As shown in FIG. 4, the conventional pipe heater has an insulating material 4 filled between a metal pipe 1 constituting the outside and a coiled heating wire 3 connected to a lead wire 2 and located inside the pipe. However, since magnesia powder used as an insulating material has hygroscopic properties,
There is a drawback that insulation resistance decreases if left in a hygroscopic atmosphere for a long time. Therefore, mixing silicone resin 5 with magnesia powder to be filled into the pipe,
An organic silicone material was applied to the inner wall of the pipe and then heated, melting the silicone material and depositing it on the surface of the magnesia powder for moisture-proofing.

However, even if a certain amount of silicone-based resin powder is mixed with magnesia powder, it is difficult to maintain a constant ratio due to the difference in specific gravity between the two, and there are also drawbacks such as the need for a drying process if silicone material is applied to the inner wall of the pipe. There is. Furthermore, when bending the heater, the pipe needs to be annealed, but since the magnesia powder inside the pipe contains silicone material, it deteriorates due to the heating for annealing and loses its moisture-proof properties. Was.

The present invention was made in view of such conventional drawbacks, and consists of storing an organic silicon material in the bottom of a bottomed metal pipe, and storing a wound heating wire inside the pipe to generate heat from the opening of the pipe. There is a compression process in which the lead wire connected to the wire is pulled out and insulating powder is filled between the heating wire and the pipe, and then the outer diameter of the pipe is reduced, and a sealing process in which the opening of the pipe is sealed with a sealing part. , the bending process is performed after annealing the bent part of the pipe away from the organosilicon material, and after the pipe is bent, the organosilicon material in the bottom is heated and evaporated at a temperature that does not lose its moisture resistance, and the entire inside of the pipe is removed. It is characterized by comprising an evaporation process in which the insulating powder is distributed over the surface of the insulating powder and deposited on the surface of the insulating powder.

Therefore, even if the bent part of the pipe away from the organosilicon material housed at the bottom of the metal pipe is annealed, the silicone material will not evaporate. can be inactivated by vapor deposition on the surface.

Examples of the present invention will be described based on the drawings.
A bottom 12 of a metal pipe 11 made of metal such as stainless steel, iron, or copper and having a bottom 12 at one end and an opening 13 at the other end is filled with resin, rubber, oil, varnish, or other materials. The organosilicon material 15 consisting of organic silicon material 15 alone or mixed with ceramic is accommodated. In this case, if the organosilicon material 15 is a solid, a disk-shaped material may be accommodated, and if it is a liquid, a certain amount may be injected into the bottom portion 12.

Next, the magnesia core 17 whose outer periphery is wound with the heating wire 15 is housed in the pipe, and insulating powder 18 such as magnesia or ceramic is filled between the magnesia core 17 and the pipe 11 and the bottom 12, and then the pipe is closed. A swaging process is performed to reduce the outer diameter of the

Further, the opening 13 of the pipe is sealed with a sealing part 20 made of an adhesive inorganic filler, and
A pair of lead wires 21 are drawn out from the sealing portion, and the other end of the lead wires is connected to the heating wire 16.

To bend the pipe, bend the part away from the organic silicon material 12 to prevent cracks from forming.
Bending processing is performed after annealing to a temperature of 1000℃ or higher.
However, if organic silicon material is mixed in the insulating powder in the pipe, the moisture resistance of the silicon material will be lost when it is heated for annealing. Since it is only the body, the bent portion to be annealed is separated from the organic silicon material 15 and does not reach a high temperature, and the organic silicon material does not evaporate. In this case, if necessary, a tool (not shown) may be used to hold the space between the bent portion 25 to be annealed and the bottom portion 12 of the pipe to block heat conduction.

After bending the heater into a predetermined shape, the bottom portion 12 where the organic silicon material 15 is located is bent so as not to lose its moisture resistance.
Heating at a temperature below 700℃, organic silicon material 15
The insulating powder is evaporated and distributed throughout the pipe, and the surface of the insulating powder is subjected to a vapor deposition treatment to inactivate the insulating powder.

Since the heater always generates heat during use, it is also possible to utilize the heat generated by the heater itself in place of the evaporation process of the silicon material.

Next, to explain the operation of this embodiment, an organic silicon material 15 is housed in the bottom part 12 of the pipe 11 having a bottomed shape, separately from the insulating powder, and after the opening is sealed, the pipe is bent. Anneal the section, then bend the entire pipe or the bottom to 300-
When heated at 700℃ for 10 minutes to 3 hours, the bottom 1 of the pipe
The vapor generated from the organic silicon material 15 contained in the pipe 2 diffuses throughout the pipe, coats and inactivates the surface of the insulating powder 18 filled in the pipe, and improves insulation. However, since the bottom 12 of the pipe 11 is a non-heat generating part for the heater,
Overheating and deterioration of the bottom part will not occur.

Conventional pipe heaters in which an organic silicon material used to inactivate the surface of the insulating powder is mixed into the insulating powder such as magnesia, cause the silicone material in contact with the heating wire to easily deteriorate due to overheating. It's better than anything else.

In FIG. 2, A shows the change in insulation resistance of the heater of the present invention, and B shows the change in insulation resistance of a conventional heater that does not use a silicone material, and shows the characteristics at 40° C. and a relative humidity of 95% or higher.

As described above, the present invention includes an organic silicon material in the bottom of the pipe, which is the non-heat generating part of the pipe, in addition to the insulating powder that is filled between the heat generating wire in the metal pipe and the pipe. Even if the part is annealed, the bent part and the organosilicon material are separated, so the organosilicon material will not evaporate and deteriorate its hygroscopicity, and the moisture-proof properties of the insulating powder in the bent part can be maintained. On the other hand, since insulating powder has durability, deterioration of insulation resistance can be prevented even if the heater is used for a long period of time.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is an overall sectional view, Fig. 2 is an explanatory diagram showing the insulation resistance characteristics of insulators of the inventive and conventional heaters, and Fig. 3 is a folded view. FIG. 4 is a partially broken sectional view of a conventional heater. DESCRIPTION OF SYMBOLS 11...Metal pipe, 12...Bottom, 13...Opening, 15...Organic silicon material, 16...Heating wire, 18
...Insulating powder, 20...Sealing part, 25...Bending part.

Claims (1)

[Claims] 1. An organic silicon material is housed in the bottom of a bottomed metal pipe, a wound heating wire is housed in the pipe, and a lead wire connected to the heating wire is pulled out from the opening of the pipe to connect the heating wire and the pipe. There is a compression process in which the outer diameter of the pipe is reduced after filling insulating powder between them, a sealing process in which the opening of the pipe is sealed with a sealing part, and a bending part of the pipe away from the organic silicon material is sintered. The bending process is performed after annealing, and after bending the pipe, the organic silicon material in the bottom is heated at a temperature that does not lose its moisture resistance, evaporates it, spreads it throughout the pipe, and deposits it on the surface of the insulating powder. A method for manufacturing a pipe heater that includes an evaporation process.