Patent GB-835450-A (GB)
Title: Improvements in or relating to method of and apparatus for forming convolutions in tubular workpieces
IPC: B21D15/06
Filed: 1956-12-21
Abstract: 835,450. Corrugating tubes. SOLAR AIRCRAFT CO. Dec. 21, 1956, No. 39088/56. Classes 83 (2) and 83 (4). Apparatus for forming a corrugation in a selected area of a tubular workpiece comprises freely rotatable means for loosely supporting said workpiece at points closely adjacent said selected area, a driven inner forming roll supported internally of said workpiece and adapted to be positioned opposite the selected area thereof, and means for displacing said inner forming roll outwardly beyond the workpiece supporting means thereby to force the said selected area outwardly to form the corrugation. A tubular metal workpiece to be corrugated is supported on rolls 24, 26 free to rotate on roller wheels 34 and spaced apart so that an inner forming roll 28 may pass outwardly between them during the formation of a corrugation. The roll 28 is fixed to a shaft 46 rotated through a chain 86 by a motor 90 and is rotatably supported in a sleeve 49 mounted in vertically slidable bearings 52, 53. In order to move the roll 28 outward to form, in cooperation with a grooved outer roll 30, a corrugation in the work, an air valve handle 106 is moved to connect an air line 108 to exhaust and to connect an air pressure line 102 to the top of an hydraulic reservoir 112 to urge fluid through a pipe 118 to push down a piston in a cylinder 80. This rocks a lever 74 secured to the sleeve 49 and, as the sleeve 49 is formed with pinions 66 engaging fixed racks 68, 70, the sleeve 49 and thus the roller 28 descends. This downward movement is halted by the closing of an hydraulic valve 120 by a dog 136 on a plate 140 rocked by an arm 144 linked to the bearing 53 of the sleeve 49. The roll 28 is returned to its original position by operation of the air valve handle 106. One corrugation having been formed the outer roller 30 is swung away and the work moved axially on the support rollers 24, 26 and a grooved plate 164 is swung up to engage the previously formed corrugation to position the work. The roll 30 is moved back and a second corrugation is formed. In another embodiment, Fig. 5, for use on a lathe a shaft 180 rotated by the lathe chuck supports, on bearings 188, 196 on assemblies 184, 192 secured to the shaft in spaced relation; guide rolls 190, 200 supporting the work W. An inner forming roll 206, on a shaft 208 rotatably mounted in the lathe crosshead, is formed with a plurality of apertures 210 through which pass bolts 202 connecting the bearing assemblies to the shaft 180, the roll 206 being thus rotated thereby. The shaft 208 is moved down in the crosshead so that the roll 206 moves down to form a corrugation in co-operation with an outer grooved roll 212. To form a deep corrugation in a metal tube W a pair of corrugations are first formed to a depth less than the desired final depth, the corrugations are then deepened, by an inner roll 234, Fig. 8, having spaced forming portions, in co-operation with an outer grooved roll 236, until the surface between them is substantially flat. The central portion of the corrugation is then deepened by an inner roll in co-operation with the outer roll 236. Finally a narrow inner roll 238, Fig. 10, and a deeply grooved outer roll 240 form the final corrugation. Alternatively after forming two corrugations of less than the desired depth, the metal is forced outwardly by inner rolls 246, 248, Fig. 13, in co-operation with outer rolls 244. The final corrugation is formed by a single inner roll in co-operation with outer rolls 244 spaced close together. For stainless-steel tubes this last step may take place after annealing.