Patent GB-841611-A (GB)
Title: Improvements in or relating to butt welding apparatus employing induction heating
IPC: B23K13/02
Filed: 1956-08-07
Abstract: 841,611. Making tubes; welding by pressure. SOC. METALLURGIQUE TECHNIQUE ET COMMERCIALE. Aug. 7, 1956 [Aug. 8, 1955; Dec. 7, 1955], No. 24164/56. Classes 83 (2) and 83 (4). [Also in Group XI] Apparatus for butt-welding a scan between opposed edges 1<SP>1</SP> of a tubular member 1 has means for continuously feeding the member in a fixed path, guide means 6 including a fixedlysupported spacer 7 located between and engaging the edges to maintain a gap of predetermined width, an elongated inductor I arranged symmetrically with respect to the path of movement and located beyond the spacer and including a conductor having a longitudinallyextending projection narrower than the gap and projecting into the gap, the inductor being fixedly supported so that the projection is aligned with the spacer and compressing means located beyond the inductor to compress the heated edges together comprising laterallyadjustable members 8, 10 arranged to exert lateral pressures on the tubular member and a vertically adjustable compressing member 9 to exert an inward pressure on the tubular member adjacent the edges, the arrangement being such that the opposed edges do not touch the projection of the inductor in their passage between the spacer and compressing means. In an embodiment a tubular steel blank 1 formed by rollers from flat strip or by deep drawing is fed by rollers M towards the inductor and compressing rollers 8-11, the edges of the blank being spaced by a projection 7 on a roller 6. The inductor comprises a U-section laminated core 3, Figs. 8 and 10, and a hollow bar 4, forming a single turn coil through which cooling liquid is circulated, about the core, the lower part of the bar being located between the legs of the U and having an elongated rectangular section at the end adjacent the roller 6 which protrudes between the blank edges and towards the other end having a section which gradually changes to that shown in Fig. 8 and finally to that shown in Fig. 10. The lower part of the bar need only be reduced in width so that at the end adjacent the compressing rollers it forms a blade. The inductor is fed with current at 500-15,000 cycles per sec. The compressing rollers comprise horizontal rollers 8, 10 and vertical rollers 9, 11 mounted in a frame, Fig. 11 (not shown), for individual adjustment at rightangles to their axes and being water-cooled. The roller 9 has an annular groove 12 to shape the weld zone but this may be omitted. In a further embodiment the inductor is arranged between two sets of rollers 6, 6<SP>1</SP>, 30, 301, Fig. 14, having projections within the tube gap, and the inductor has no magnetic core but is of circular section copper or bronze tube with a projection 4<SP>1</SP>, Fig. 16, entering between the gap edges. Cooling liquid is circulated through the inductor via orifices 17. A set of compressing rollers, which may be arranged as in the first embodiment, are provided beyond the inductor and rollers C drive the tube through sizing, cooling, straightening and sectioning stages.