GB509188A - Process and apparatus for expanding tubes - Google Patents

Abstract

509,188. Making tubes. MANNES MANNROHREN-WERKE. May 23, 1938, No. 15303. Convention date, May 28, 1937. [Classes 83 (ii) and 83 (iv)] Drawing; tube expanders.- In apparatus for expanding tubes by a mandrel, the tube is clamped at a part which has already been expanded and the mandrel is given a relatively short -stroke reciprocating movement, the tube being held fixed during the expanding stroke and moved with the mandrel during the idle stroke. In one form of machine, Fig. 2, the mandrel a is reciprocated by a driving crank b and the tube d issuing from a furnace c is held by a clamp f during the expanding stroke. On the idle stroke the mandrel carries the tube backwards. If desired, any irregularities due to the clamp may be removed by a die ring o and in order to move the tube through the ring an auxiliary clamping device p is provided and is moved backwards by rods r on the idle stroke of the mandrel. In order to avoid preliminary expanding of the end of the tube before placing it in the machine, the machine may be provided, as shown in Fig. 4, with a secondary clamp f<1> in front of the mandrel and operative only until the expanded end of the tube engages with the main clamp f. Both clamping devices f and f are operated hydraulically, the plungers u<1> and u<2> being pressed against the tube on the expanding stroke of the mandrel and released on the idle stroke by means of a piston t operated from the crank b. A die ring o also driven from the crank b may be provided.