GB1013315A - Method and apparatus for helically welding strip material and helically finned tube made thereby - Google Patents

Abstract

1,013,315. Welding by pressure; coiling; making gilled tubes. BROWN FINTUBE CO. May 19, 1964 [June 6, 1963], No. 20590/64. Headings B3A, B3E and B3R. A helical fin is welded to a cylindrical member T, e.g. a tube or bar by rotating and advancing the member, pressing an edge of a strip S against the member T at the weld zone, passing current between electrodes contacting the member T and the strip S to weld the edge of the strip S to the member T and supporting the member T against the welding pressure exerted by the strip S by a device engaging the welded strip S. High-frequency welding current of at least 50,000 cycles per second is used together with a welding pressure sufficient to deform and thicken the strip S adjacent the weld. A tube T is rotated and advanced by three pairs of skew rolls 13 . . . 15 rotated by shafts 52 driven by a motor 5 through a clutch 4. Each roll is knurled and tapered towards the other roll of the pair. The axis of rotation of each pair of rolls is angularly adjustable and the upper pair 15 is vertically adjustable. The rolls are interchangeable with other sets of different size and the frame 11 supporting the rolls is mounted on a base 1 by an interchangeable spacer block 12. The welding pressure is taken by a supporting roll 101 engaging several turns of the welded strip and mounted on a bracket 103 vertically adjustable on a bracket 104 angularly movable about a pivot 67 attached to the base 1. The welding unit is mounted on a plate 64 attached to the base 1 by the pivot 67 whose axis passes through the weld point W. Welding pressure is applied to the strip S by a deeply grooved copper alloy roller 95 carried on an arm 91 pivoted on a support 88 adjustably secured to the plate 64. An air cylinder 93 provides the welding pressure. Strip S, the leading end of which is spot welded to the tube T or to the trailing end of the welded fin F is drawn through a guide 145 attached to a frame 71b supported on the plate 64 by a pedestal 71 including an interchangeable spacing member 71c. Welding current is supplied through bars 105, 106 depending from a transformer 8 adjustably secured in guideways 73 on the frame 71b. An electrode 76 is pressed against the side of the strip S by an air cylinder 132 acting on an electrode holder 128 slidable in guides 129, 130 on a block 126 fixed to the bar 106. An electrode 75 transversely adjustable in a dovetail mounting 117 on a member 113 is pressed against the tube T by an air cylinder 119 acting on the member 113 which is slidably mounted on a block 111 depending from the bar 105. The various electrode mounting members are liquid cooled and water is sprayed on to the tube T and fin F adjacent the weld zone. The strip S is fed through a guide aperture 143 formed in insulating members 136, 138 secured to the blocks 111 and 126. An interchangeable adaptor 144 is fixed in the aperture 143.