Patent GB-989661-A (GB)
Title: Methods and means for forming corrugations on tubing
IPC: B21D26/043
Filed: 1963-01-11
Abstract: 989,661. Corrugating tubes. CALUMET & HECLA Inc. Jan. 11, 1963 [Jan. 25, 1962], No. 1397/63. Headings B3A and B3Q. A method of forming an annular corrugation in a length of metal tubing comprises forming fluid tight junctions between the wall of the tubing and seals within the tubing at two axially spaced locations to define a chamber within the tubing, applying fluid pressure to the chamber to bulge the tubing wall between the junctions and moving the junctions towards each other by axially compressing the wall between the junctions while maintaining the fluid pressure within the chamber to further bulge and distend the wall into engagement with abutment surfaces surrounding the tubing, the abutment surfaces being generally complementary in shape to the corrugation. Apparatus comprises a frame 12 on which are mounted subframes 28, 30 vertically movable along ways 26 by pairs of hydraulic rams 32, 34, 60, and a vertically centrally positioned arbor assembly 48 comprising an outer casing 50 secured to the frame 28 and at its upper end to a closure assembly 52. Pairs of dies 70, 86, having cavities 72, 90 complementary in shape to the corrugations to be formed are attached to horizontally slidable frames 76, 92 operated by hydraulic rams 80, 94. The arbor assembly 48 comprises upper and lower sealing units which engage the inside of a length of tube 68. The upper unit comprises an elastomeric seal 102, e.g. natural rubber or neoprene, and a hose piece 106 secured to a collar 110 slidable along a spindle 112 and within a thrust sleeve 108 attached to a tubular strut 116 which is rigidly secured to the closure 52. Hydraulic fluid supplied via a conduit 122 is admitted to a chamber 120 to effect upward movement of the piece 106 towards the sleeve 108 and compression of the seal 102 to bulge it against the tube wall. The lower unit comprises an elastomeric seal 104, a nosepiece 132 attached to the spindle 112, a mandrel 136, and a bushing 138, the seal is similarly compressed and bulged by upward movement of the mandrel 136 under the influence of hydraulic pressure via conduit 146 and chamber 144. In operation the tube 68 is loaded upwardly over the mandrel 136, the lower dies 86 closed and the seal 104 compressed, the frame 28 moved to the top of its predetermined stroke and the upper dies 70 closed and the seal 102 compressed. Water under high pressure is delivered via spindle 112 into the chamber between the two seals to bulge the tube and with the pressure maintained the frame 28 is lowered to effect lowering of the dies 70 and seal 102 into contact with the top faces 88 of the dies 86 to produce a corrugation. Subsequently the upper seal is relaxed, the dies 70 retracted and the frame 28 raised, followed by the relaxing of the lower seal which allows the water to be discharged by falling freely over the mandrel 136. Before the dies 86 are retracted the frame 30 is lowered to axially index the tube, the dies 70 actuated to regrip the tube, the seal 102 re-made and the dies 86 subsequently retracted, raised and advanced to re-engage the corrugation previously formed. Sequential control of the operations is carried out by an electro-mechanical timer mechanism in conjunction with solenoid operated valves. Stroke adjustments are provided on the couplings between the hydraulic rams and their frame members.