GB1050689A - - Google Patents

Abstract

1,050,689. Welding by pressure. INTERTHERM Ltd. Nov. 5, 1964 [Dec. 16, 1963], No. 49585/63. Heading B3R. In electric welding apparatus for welding the seam of a tube and the like utilizing high frequency energy supplied through a primary coil and a member including an impedance core coaxially placed in the tube, the member is provided at each opposite end with an end piece of magnetizable material and magnetic means are provided to magnetically influence the end pieces to hold the member against longitudinal movement. Strip aluminium is formed by rollers into an open seamed tube 1, Fig. 1 (not shown), the edges of which are held apart by a guide 2 after passing the final forming rollers and the tube is passed through an induction coil 4 supplied with R.F. current. Rollers 6 beyond the coil applies pressure to the heated edges which weld. The welded tube is then scarfed, possibly drawn and then cut into storage lengths. A ferrite rod core 7 contained in a P.T.F.E. tube 8 is provided to lie within the tube coaxially of the coil 4 and steel caps 10, 11 are provided at the ends of the P.T.F.E. tube, a tube 9 being provided in the upstream end of the tube 8 to provide coolant flow through the tube 8. Coolant, e.g. water soluble oil is also flowed through the tube 1 to be welded about the P.T.F.E. tube 8. A coil 12 on slides is arranged about the tube 1 adjacent the end cap 10 and a similar coil is arranged adjacent the end cap 11 and D.C. current is supplied to these coils to maintain the end caps in the desired position. A permanent magnet may replace coils 12, 13. The ferrite core may not be enclosed in a P.T.F.E. tube when it is of greater length to extend between the caps 11, 12 or of shorter length with quartz rod spacers adjacent the end caps. Ferrous tubes may be welded.