GB595630A - Improvements relating to the shaping of metal tubes - Google Patents

Abstract

595,630. Corrugating; stamping screw-threads. DE HAVILLAND AIRCRAFT CO., Ltd., WAKELIN, J. P., and OATEN. S. J. Aug. 24. 1944. No. 16159. [Class 83 (iv)] Apparatus for bulging or outwardly swaging a tube by an endwise compression of a resilient plug which forces the tube into contact with a shaped die comprises a base plate carrying a hydraulic ram, a clamping block for securing the die, the tube and the plug in their correct relationship and a lever connecting the ram to the plug compressing means. The tube 15 is inserted in a sectional die 19, 20 so that it abuts a steel collar 29 mounted within a groove 25 of the die. The part of the die surrounding the tube is formed with an annular recess or groove 23, as shown, Fig. 2, or may be provided with a number of isolated recesses or with a helical recess for forming a screwthread. Within the tube is a rubber plug 31 and a head 33 adapted to be moved towards the collar 29 by a drawbar 35 and compress the plug and expand the tube into the recesses of the die as shown. The two parts of the die are located in correct relation to each other by dowels 37, Fig. 4, and are normally urged apart by springs 41. The machine for carrying out the operation comprises a rigid steel plate 49, Fig. 7, on which is bolted a clamping block 45 and through an aperture in which depends the hydraulic cylinder 47. In operation, the die parts are clamped together and against the block 45 between pins 57 projecting through the plate 49 and clamping screws 55 carried by a projecting portion of the block 45.- Pins 57 are adapted to be raised and lowered by an eccentric 59 rotatable through 180 degrees by a handle 65 and by springs 69 respectively to facilitate the releasing and reclamping of the die once the screws 55 have been correctly adjusted. The end of the drawbar 35 screws into a crosshead 71 sliding in a guideway formed. in the block 45 and is moved to compress the rubber plug by means of a piston 85 in the cylinder 47. acting through piston rod 83 and bell crank levers 77 pivoted in the block 45 and engaging each end of a pin 75 passing transversely through the cross-head 71. Liquid is supplied to the cylinder by a hand-operated pump, the hydraulic circuit including an adjustable relief valve and also a valve, which upon the operation of a hand-lever, is moved from its seating by a spring to connect the cylinder to the tank 87 when it is required to release the pressure on the drawbar.