JPS5788923A - Method for manufacturing double tube nozzle - Google Patents

Abstract

PURPOSE: To efficiently manufacture double tube nozzles, by installing metallic wires which closely contact with the inner surface of the outer tube, to the outer periphery of the inner tube.

CONSTITUTION: Plural grooves 22 are installed at an interval along the circumference into the outer periphery of an inner tube 2 in the direction of the tube 2 for the overall length, and a metallic wire 5 having a diameter which is larger than the depth of the grooves 22 is fitted into the grooves 22 for the overall length. Both ends of the metallic wire 5 fitted into the grooves 22 are fixed to the inner tube 2 by spot welding or with adhesives. Then, an outer tube whose inner diameter has a little clearance against the metallic wire 5, is put on the inner tube 2. A deep drawing is performed by passing the outer tube 3 through a drawing die. The inner surface of the outer tube 3 is pressure welded to the metallic wires 5 and the inner and the outer tubes 2 and 3 are firmly fixed to each other. When the above mentioned procedure is applied, the metallic wires 5 will not bend and the interval between each metallic wire 5 and 5 is not changed, and, therefore, a straight circulating space having a narrow thickness corresponding to the diameter of the metallic wire 5 is formed between the inner and outer tubes 2 and 3 and each metallic wire 5.

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