JPS5911196B2 - 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 made of heat-resistant alloy pipe used in electric stoves, electric roasters, and the like.

Conventionally, when making sheathed heaters using metal pipes such as stainless steel pipes, a filling material made of a mixture of magnesia powder and silicone resin powder was used to keep the insulation resistance of the sheathed heater high. However, when bending ,
When a sheathed heater is annealed at around 800℃, the silicone resin mixed with the magnesia powder used as the filling material deteriorates due to this annealing temperature, and the silicone resin added to improve the electrical insulation resistance of the sheathed heater becomes completely ineffective. On the contrary, the silicone resin in the heater part of the sheathed heater was carbonized, the insulation resistance of the sheathed heater was reduced, and there was a drawback that a disconnection accident occurred.

The present invention provides a sheathed heater using a heat-resistant alloy such as a stainless steel pipe, and an excellent electrically insulating material using a material made of a mixture of magnesia powder and silicone resin. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part of a sheathed heater showing an embodiment of the present invention. 1 is a metal pipe made of a heat-resistant alloy such as a 10 stainless steel pipe, 2 is a terminal, and 3 is a coiled heater wire with a terminal attached.

4 is an electrical insulating material made of magnesia powder, and 5 is a sealing material, which is a material that is a mixture of magnesia powder and silicone resin in an amount of 5 to 15% by weight, and is placed in the terminal portion deeper than 5n from the end of the metal pipe.

Next, a method for manufacturing a sheathed heater will be described. A heat-resistant alloy pipe 1 made of a stainless steel pipe or the like is filled with electrical insulating material 4 made of magnesia powder by reducing the diameter of a metal 20 metal pipe by about 10%, except for the terminal part deeper than 5 mm from the end of the metal pipe, to a filling rate of about 75%. A heat-resistant alloy pipe such as a stainless steel pipe is annealed at around 800°C, and 5 to 15% of 25 silicone resin made of magnesia powder, silicone resin powder, silicone varnish, etc. is added to the terminal part 2 deeper than 5 mm from the end of the metal pipe. The wt-mixed sealing material 5 was inserted, and the diameter of the entire metal pipe 1 was reduced by 5 to 10%, so that the filling rate of the electrically insulating material was 80 to 85%, and the filling rate of the sealing material was 70% or more. Afterwards, the silicone resin is heated at 200° C. to 400° C.30° C. to melt it. When making a sheathed heater using heat-resistant alloy pipes such as stainless steel pipes, the annealing temperature is around 800°C.
The filling material, which is a mixture of magnesia powder and silicone resin, cannot be used because the silicone resin degrades to 35%.

First, fill the part of the sheathed heater with the heating wire only with magnesia powder, reduce the diameter of the metal pipe 1 by about 10% to increase the filling rate to about 75%, and annealing it at about 800°C to a depth of 5111 mm from the end of the metal pipe. A sealing material 5, generally 5n to 4011E, which is a mixture of magnesia powder and 5 to 15% Wt of silicone resin, is inserted into the terminal part 2, the metal pipe is reduced in diameter by 5 to 10%, and the filling rate is increased.
By firing at a temperature of ℃ to 400℃ and melting the silicone resin,
Perfectly seal the terminals of the sheathed heater. 1 metal pipe
After reducing the diameter to around 0% and annealing, the diameter is reduced again by 5 to 10%. For metal pipe diameter reduction of 5% to 10% or less after annealing,
There is little work hardening of metal pipes, making bending easier. The magnesia powder containing the heater wire is 8 due to diameter reduction.
The filling rate is as high as 0 to 85%, and the sealing material has a high filling rate as high as 70% or more. Since only 5 to 15% Wt of silicone resin is mixed with magnesia powder, there is no sealing effect unless the silicone resin is melted after the filling rate of the sealing material is 70% or more. The mixture of silicone resin is 5%
If it is less than Wt, there is no effect, and if it is more than 15% Wt, thermal shrinkage is large and cracks are likely to occur, reducing the effect.
The optimum length of the sealing material, which is a mixture of magnesia powder and silicone resin, is from 511 m to 4011 m. As described above, the sheathed heater manufactured by the sheathed heater manufacturing method according to the present invention can provide a high-quality sheathed heater that always maintains high insulation resistance.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of essential parts of the sheathed heater of the present invention. 1... Metal pipe, 2... Terminal, 5... Sealing material.

Claims (1)

[Claims] 1. A coiled heater wire 3 with a terminal 2 attached is placed in the center of a metal pipe 1, and an electrical insulating material 4 made of magnesia powder is filled between the metal pipe and the coiled heater wire, and then annealed. A sealing material 5 made of a mixture of magnesia powder and silicone resin is inserted into the terminal part deeper than 5 mm from the end of the pipe, the diameter of the entire metal pipe 1 is reduced, and the filling rate of the electrical insulating material and sealing material is increased to make silicone. A method for manufacturing a sheathed heater that heats and melts resin.