GB694472A - Improved machine for swaging metal tubes - Google Patents

Abstract

694,472. Making tubes. GENERAL MOTORS CORPORATION. July 26, 1951 [July 28, 1950], No. 17710/51. Classes 83 (ii) and 83 (iv). Swaging.- A tube swaging machine comprises a mandrel and oppositely disposed dies which fit around the tube and means for recurrently striking the dies to produce a swaging or hammering action on the tube as it is drawn over the mandrel, the mandrel having its working surface relieved over alternate short zones along the length thereof. The machine has a hollow carrier 20 j journalled in a housing 21 and rotated by means of pulleys 22 and 23 driven by a motor 25 and belts 24. The housing has a tubular hub 27 which supports a circular row of rolls 26. The portion of the carrier 20 extending coaxially in the circular space defined by the rolls 26 has a diametral recess in which a pair of dies 31, 32 and die hammers 35 and 37 are slidably supported. The outer end of each hammer has a roller 36, 38 which is successively engaged by the rolls 26 as they are carried round by the rotating hub 27. The dies pound the external surface of the tube 33 as it is fed through the machine by two sets of rollers 50, 51. The rollers 50 are idle and the rollers 51 driven through bevel gears from the motor 25. A mandrel 40 is held in the pass between the dies by a rod 41. The input end of each die has a tapered lead 43 and the mandrel has a tapered outer end 42. The working surface of the mandrel has alternate full diameter zones A, C, E and G, and intermediate smaller diameter zones B, D and F. The zones A, C, E and G are 0.011 inches smaller in diameter than the inside of the tube and the zones B, D and F are 0.004 inches smaller in diameter than the zones A, C, E and G. In operation, the tube is inserted into the pass between the dies 31 and 32 and as the carrier 20 rotates the hammers 35 and 37 repeatedly pound the dies 31 and 32 against the tube wall. As the tube passes over the larger zones metal is displaced by the dies towards the relieved zones, resulting in a bur. nishing which provides a mirror-like internal surface to the tube.