JPH081595Y2 - Radiant tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a radiant tube for heating molten metal.

[Conventional technology]

Generally, molten metals, particularly aluminum, zinc, copper, etc., generate oxides when heated by a combustion method used in a direct flame, which adversely affects the quality of the metal. Therefore, a radiant tube that does not generate an oxide is often used for heating and melting the molten metal as described above. In this radiant tube system, a ceramic heating element fixed at one end is inserted into the radiant tube, and the entire tube is heated in a temperature controllable manner by energizing this heating element. In such a radiant tube, it is necessary to electrically insulate the heating element from the tube. Therefore, conventionally, a bottomed insulating sleeve is capped on the free end of the heating element and the upper circumference of the free end in the tube. By doing so, an electric accident due to the free end of the heating element coming into contact with the inner wall of the tube was prevented.

[Problems to be solved by the invention]

However, in the conventional radial tube as described above, since a cap-shaped one having a bottom is capped on the free end of the heating element as an insulator between the tube and the heating element, the heating effect is excellent although the insulation effect is excellent. The free end face and the free end upper peripheral part of the are covered with this cap-shaped insulator, and the heat of the heating element from these free end face and free end upper peripheral part stays in the insulator and is circulated in the tube. However, if the heating element is locally heated, the heating element is damaged, and if the heating element becomes hot, a part of the ceramic SiC is oxidatively decomposed and vaporized and vaporized.

An object of the present invention is to provide a radiant tube which solves the above-mentioned conventional problems, prevents local heating, has an excellent insulating effect, and has a long life.

[Means for solving problems]

In this invention, the sleeve as an insulator is made into a bottomless cylindrical shape, this sleeve is loosely inserted in the heating element, and this sleeve is attached by inserting a heat-resistant ceramic pin into the hole penetrating the sleeve and the heating element. Thus, the above-mentioned problems are achieved.

[Action]

In this invention, the bottomless cylindrical sleeve is attached by a heat resistant pin so as to be loosely inserted into the free end of the heating element, so that the free end of the heating element and the upper peripheral portion of the free end are covered by the sleeve as in the conventional case. Therefore, an air circulation space is created between the free end of the heating element and the bottom of the tube tip, and due to this space and the gap between the heating element and the tube, the heat from the heating element also enters the tube from the tip of the heating element. It circulates, and effective heating can be performed without causing problems such as local heating of the insulator.

〔Example〕

FIG. 1 is a cross-sectional explanatory view of a radiant tube according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a tube, which is usually in the shape of a bottomed cylinder made of a metal material or a refractory material. A heating element 2 made of silicon carbide is inserted from the open end side of the tube 1. The tube 1 and the heating element 2 are heat-resistant in a hole through which the cylindrical sleeve 3 penetrates the heating element 2 and the sleeve 3 in the vicinity of the free end of the heating element so that the heating element 2 does not contact the inner wall of the tube 1. By inserting the ceramics pin 4, it is attached to the heating element in a loosely inserted state.

As described above, according to the present invention, the sleeve 3 for insulating the tube 1 and the heating element 2 from each other is formed of a bottomless cylindrical shape, and the sleeve 3 is attached in the vicinity of the free end of the heating element 2 in a loosely inserted state. Therefore, the air circulation space 5 is formed between the free end portion of the heating element 2 and the bottomed portion of the tube 1, and a gap is formed between the heating element 2 and the sleeve 3. Therefore, when this radiant tube is used, that is, when the heating element 2 is energized to heat the heating element 2, the heat from the tip of the heating element 2 is diffused through the air circulation space 5, so that the heating element 2 Local heating is prevented and heat is evenly transferred to the tube 1.

[Effect of device]

As described above, according to this invention, the heat-resistant sleeve provided on the free end side of the heating element is formed of a bottomless cylindrical shape, and the heat-resistant sleeve is heat-resistant so as to be loosely inserted with the heating element. Since it is attached to the heating element with a heat-generating pin, an air circulation space is formed between the free end of the heating element and the bottom of the tube, and a gap is created between the heating element and the heat-resistant sleeve. The heat from the body tip is prevented from being blocked by the sleeve, so that the heating element is prevented from being locally heated, and the life of the heating element is prolonged while ensuring electrical insulation.

[Brief description of drawings]

 FIG. 1 is an explanatory sectional view showing an embodiment of the present invention. 1 ... Tube, 2 ... Heating element 3 ... Sleeve, 4 ... Heat resistant pin 5 ... Air circulation space

Claims (1)

[Scope of utility model registration request] 1. In a radiant tube in which a silicon carbide heating element fixed at one end is set, a bottomless cylindrical sleeve as an insulator is loosely inserted into the heating element at the free end of the heating element. A radiant tube characterized in that a sleeve is attached to a heating element by inserting a heat resistant ceramics pin into a hole penetrating the sleeve and the heating element.