GB1340245A - Metal tubes - Google Patents

Abstract

1340245 Welding by fusion; making helically seamed tube; coiling helices HOESCH MASCHINENFABRIK DEUTSCHLAND AG 2 Dec 1971 55997/71 Headings B3A B3R and B3E Tube sections are produced from metal strip 1 by (i) continuously helically convoluting a metal strip to form a tube with its adjacent convoluted strip edges 11, 12 abutting or slightly spaced, (ii) tack arc welding said adjacent edges at a first welding speed during the convoluting process, (iii) parting-off a section of the tack-welded tube and axially conveying said section to a station downstream of the convoluting and tack-welding station, and (iv) continuously finish arc welding the tack-welded edges at a welding speed slower than the tackwelding speed. The tack and finish welding stations may comprise single or a plurality of interiorly and/or exteriorly positioned welding heads. In Figs. 1, 2, the convoluting and tackwelding station apparatus comprises stock strip feed rollers 22, 23 driven via a geared, preferably variable speed, motor 24, bending rollers 201-203 and radially adjustable support rollers 204. The pitch angle of the rollers 201- 204 is lever adjustable. The rollers 201 are mounted on an arm 27 which is vertically adjustable to vary tube diameter. A welding support 28 is vertically adjustable by a cylinder 281, e.g. hydraulic. A consumable electrode arc-welding head 21 is adjustably carried by an arm 25 which is journaled by a support 271 for pivotal and sliding movements about and along the longitudinal tube axis 5-5. The support 271 is adjustably carried by the arm 27. During the helical movement of the adjacent strip edges, the head 21 is given a cylic oscillating movement comprising a limited helical forward movement (at a speed faster or slower than the strip edge speed) and a quick return movement. The head helical oscillation rotational component is effected by a geared motor 251 which is connected to the arm 25 via a coupling 252, a rod 254 and lugs 255, 256. Rotational amplitude is limited by the abutment of an arm 253 of the rod 254 with adjustable contact switches 2581, 2591 connected in the circuit of the geared motor 251. The head helical oscillation axial component is effected by a double-acting displacer 257 which acts on the motor 251 and is controlled by an optical light point strip edge sensing device 214 mounted on the arm 25. Alternatively, the axial component may be effected by a follower roller 2532 connected to the arm 253 and pressed, by a spring 2531, against one of the strip edges. In Fig. 3 (not shown), the welding head is mounted on a carriage (29) which has wheels (e.g. sprung ball rollers) engaging the strip and is given the rotational and axial components of the helical oscillation by separate displacing devices. In Fig. 4, a roller conveyer 32 for the partedoff tack-welded tube section comprises rollers 321-325 which are lowered when the section is in finish welding position. Rollers 341, 342 are provided to axially locate the tube section. The latter is rotated during welding by roller pairs 33 driven synchronously by motors 331. Interior and exterior arc welding heads 31 are rotational adjustably mounted on carriages 37, 38 driven, during the welding, axially of the tube, along vertically adjustable guides 35, 36, by motors 372, 382 via friction rollers 373, 383. A circuit 301 controls the rotational speed of the tube and the axial speed of the welding heads. Described strip edge preparations include double-vee with plain (Fig. 11, not shown) or square-faced projecting (Fig. 13, not shown) root faces. The tack-welding may be intermittent (Fig. 5, not shown) or formed to be continuous by intercalation of welds from multiple heads on one or both sides of the strip (Figs. 6-10, not shown). In Fig. 16 (not shown), the edge preparation projecting ribs are alternately bevelled through from opposite sides to accommodate tack welds intercalated from said opposite sides.