JPS634959Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to an electric furnace with a resistance heating element for obtaining high temperature, and particularly to an electrical connection between the electrode and the heating element.

(Prior art) Conventionally, in this type of electric furnace, the connection between the electrode and the heating element is either tightened together with a bolt made of the same material as the heating element, or a water-cooled metal electrode is used. Some were screwed directly into the heating element, and others were screwed into the heating element itself. In the electric furnace of shingles, especially at 2000℃
In devices for obtaining higher temperatures, as the temperature is raised, the heating element and electrode become incompletely tightened together due to the difference in thermal expansion, resulting in poor contact, and the heating temperature increases. Becoming unstable,
The reliability was poor due to discharge in the electrode part and damage to the electrode part. In addition, it was extremely unstable to pass a large current of approximately 100A.

(Purpose of the invention) The present invention solves the above-mentioned conventional problems, and provides a highly reliable resistance heating element electric furnace in which the electrodes and the heating element can be tightly connected to each other so as to tighten them. The purpose is to

(Structure of the invention) The resistance heating element electric furnace of the invention is provided with an arc-shaped heating element lead part on the heating element side so as to be inscribed in the arc-shaped electrode, and the inner peripheral part of the arc-shaped heating element lead part is , a ring-shaped spacer having a taper is inserted to press and hold the arc-shaped heating element lead portion against the electrode.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

Fig. 1 is a cross-sectional view of a resistance heating element electric furnace of the present invention applied to a tubular furnace for drawing a silica-based optical fiber base material, and Fig. 2 is a cross-sectional view taken along the - line in Fig. 1. .

This wire drawing furnace has a cylindrical carbon heating element 4 inside a water-cooled furnace body 1, and a heat insulating material 7 is arranged around the heating element 4. An optical fiber base material 8 is introduced and a fiber 9 is drawn. Lead parts 5a and 5b come out from the heating element 4, and these lead parts 5a and 5b are connected to water-cooled metal electrodes 2a and 5b.
2b is pressed and connected from the inside by an insulating spacer 6 made of quartz glass having a tapered outer circumferential portion. That is, as shown in FIG. 2, the electrodes 2a and 2b have a cylindrical shape and form a pair, and the heating element lead portions 5a and 5b are also formed in a concentric pair to correspond to the respective electrodes 2a and 2b. It is located in The spacer 6 is in the form of a single ring, and has a tapered outer peripheral portion that contacts the lead portions 5a and 5b. When assembling the heating element 4, the heating element lead parts 5a and 5b are set at predetermined positions of the pair of electrodes 2a and 2b, and a ring-shaped spacer 6 is placed inside the lead parts 5a and 5b.
Just plug it in and you're done. In this way, electrode 2
The connection portion between a, 2b and the heating element 4 has an extremely simple structure.

When the heating element 4 is energized, as the temperature of the heating element increases, the temperature of the lead parts 5a and 5b also increases. On the other hand, since the electrodes 2a and 2b are water-cooled, a rise in temperature is suppressed. Further, the spacer 6 also expands as the temperature rises. As a result,
As the temperature increases, the lead parts 5a, 5
b will be tightened more strongly against the electrodes 2a, 2b, and the higher the temperature, the higher the contact force between the electrodes 2a, 2b and the lead portions 5a, 5b.

By the way, in this example, when the heating temperature is 2200°C, the lead parts 5a, 5b and the electrodes 2a, 2b
No damage was observed to the electrodes 2a and 2b until the current density at the contact surface was about 170 A/cm ² , and continuous operation over several days could be carried out stably.

As explained above, the resistance heating electric furnace of this invention has an arc-shaped electrode with a corresponding arc-shaped heating element lead inscribed therein, and the heating element lead is pressed against the electrode by a spacer inserted inside the lead, so that the difference in thermal expansion between the electrode and the spacer, especially at high temperatures, can ensure a more reliable connection between the heating element lead and the electrode. Therefore, a highly reliable resistance heating electric furnace can be provided with a simple connection structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line - in FIG. DESCRIPTION OF SYMBOLS 1...Furnace body, 2a, 2b...Electrode, 4...Heating element, 5a, 5b...Heating element lead part, 6...Spacer.

Claims (1)

[Scope of utility model registration request] In a resistance heating element electric furnace having a heating element made of a cylindrical heat-resistant conductive material, an arc-shaped electrode is provided along the inner wall of the furnace body, and an arc-shaped heating element lead portion on the side of the heating element is inscribed in the electrode. be prepared,
A tapered ring-shaped spacer is inserted into the inner peripheral portion of the arc-shaped heating element lead portion, and the arc-shaped heating element lead portion is pressed against and held by the arc-shaped electrode. Resistance heating element electric furnace.