JPS6081786A - Long 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 Field of Industrial Application The present invention relates to a long heater used as an industrial heating source such as a heater for an electric furnace.

Conventional configuration and its problems Sheathed heaters have traditionally been used as heaters for electric furnaces.

Eve has recently been widely used due to its ease of temperature control and thermal efficiency.

This sheathed heater generally has the following characteristics, as shown in Figure 1.
A coiled heating wire 13 having electricity output terminals 12 at both ends is placed in the center of the metal pipe 11, and magnesia powder 14 is filled between the metal pipe 11 and the heating wire 13. Further, both ends of the metal pipe 11 are sealed with a low melting point glass 16 and a heat resistant resin 16 as necessary.

However, conventional sheathed heaters having such a structure are unsuitable for so-called long heaters, which have a length of several meters and are used in electric furnaces and the like.

This is because a sheathed heater with a conventional structure generally has a coiled heating wire 1 that has electrical extraction terminals 12 at both ends.
3 is placed over a medium heat of a metal pipe 11 using its tension, and by applying vibration to the metal pipe 11, the magnesia powder 14 is filled. Terminal 1 to remove stains caused by vibration during filling
2 and the heating wire 13 are eccentric, and the dielectric strength between the metal pipe 11 and the electrical outlet terminal 12 is reduced, which significantly impairs the comfort of the sheathed heater.

OBJECTS OF THE INVENTION The present invention solves these conventional drawbacks and provides a long heater with excellent electrical properties, particularly dielectric strength.

Structure of the Invention The present invention provides a cylindrical ceramic core having a hole in the center through which an electrical outlet terminal and a coiled heating wire pass, and a plurality of holes around the hole through which magnesia powder passes. By providing each of the electricity extraction terminal and the heating wire at at least one point of force,
A long heater with excellent dielectric strength that prevents eccentricity of the electrical outlet terminal and heating wire! ).

Embodiment 1 Etsumei Embodiments of the present invention will now be described with reference to FIGS. 2 to 4.

Metal pipe 1 has a length of 1600 mm and an outer diameter of 12 mm and 7 mm.
+Jm-wall thickness o, 63rrtttノNCF s oo
(trade name: Incoloy 800), and as the heating wire 2, a first type nichrome wire with a wire diameter of 0.577+ff was used. This heating wire 2 is made into a coil shape with a winding diameter of 2 mm, and both ends have an outer diameter of 2 mm.
An electrical outlet terminal 3 of mm was connected.

On the other hand, 4 has a hole 5 with an outer diameter of 2.61/r) in the center through which the coiled heating wire 2 and the electrical outlet terminal 3 can pass, and magnesia powder 6 penetrates around this hole 60. Hole 7 with outer diameter 1, 6 MlN capable of
．． It is a cylindrical ceramic core made of a magnesia molded body with an outer diameter of 1 o Il 1 m and a wall thickness of 611 m. Holes 5 are passed through the cylindrical ceramic core 4 at several locations in the electrical outlet terminal 3 and the coiled heating wire 2, and the core is fixed with a heat-resistant inorganic adhesive.

As shown in FIG. 4, the electric outlet terminal 3 having the cylindrical ceramic core 4 was placed on the lower side, and was positioned in the center of the metal pipe 1 using the electric outlet terminal fixing jig 8.

After that, magnesia powder 6 is filled according to the conventional method, rolled, diameter-reduced and annealed, and then low-melting glass 9
, length 180Q after sealing process with heat resistant resin 10
7/lff1, 10 long heaters with an outer diameter of 117+7ff
This was completed and the samples were numbered 11-20.

At this time, for comparison, the above cylindrical ceramic core 8
Similarly, 10 long heaters having the structure of a conventional sheathed heater without a sheathed heater were completed and designated as sample numbers 1 to 10.

The insulation ij·I force of each completed long heater was measured, and the results are shown in Table 1.

(Left below) As is clear from Table 1, the dielectric strength of the long heaters with sample numbers 1 to 1o, which have the structure of conventional sheathed heaters, is 5.
It was between 007 and 11007, which was a very low level.

On the other hand, in the long heaters of sample numbers 11 to 20 in the examples of the present invention, the dielectric strength is 2000 to 2500V,
It showed very high dielectric strength.

As described above, according to the long heater according to this embodiment, the cylindrical ceramic core 4 is provided at several locations on the electrical outlet terminal 3 and the coiled heating wire 2, so that the electrical outlet terminal 3 having a long dimension can be used. It will not become eccentric.

For this reason, it was possible to significantly increase the insulation side force compared to conventional sheathed heaters.

In the present invention, a molded magnesia body is used as the cylindrical ceramic core, but the present invention is not particularly limited to this.

In addition, the diameter and number of holes through which magnesia powder penetrates are φ
1, 5 +, /ff, respectively, it is not limited to 4 pieces, but it is sufficient if the structure is sufficient to allow the magnesia powder to pass from the top to the bottom of the cylindrical ceramic core. Although it is better to have a larger number, it is not particularly limited.

Effects of the Invention As is clear from the above description, the present invention has a hole in the center through which an electrical outlet terminal and a coiled heating wire pass through, and a plurality of holes around the hole through which magnesia powder passes. By providing a cylindrical ceramic core at at least one stress point of each of the electrical outlet terminal and the heating wire, it is possible to obtain a long heater with excellent dielectric strength, and its industrial value is immense. be.

4. (Principal explanation of page 31) Figure 1 is a 11J1 diagram of a conventional sheathed heater, Figure 2 is a cross-section II'1.r diagram of a long heater showing an embodiment of the present invention,
FIG. 3 is an explanatory diagram of the cylindrical ceramic core, and FIG. 4 is an assembly diagram.

2...Heating wire, 3...Electricity outlet terminal,
4... Cylindrical ceramic core, 5, 7-... Perforated hole, 6... Magnesia powder.

Name of agent: Patent attorney Toshio Nakao and one other person
Mete ~ \ size (zum)

Claims (1)

[Claims] A cylindrical ceramic core having a hole in the center through which an electricity output terminal and a coiled heating wire pass, and a plurality of holes through which magnesia powder passes through the periphery of the hole, is provided. A long heater provided at at least one force point or more for each of the above.