GB669163A - Improvements in method and apparatus for reshaping metal tubes - Google Patents

Abstract

669,163. Stamping. SEEBER, R. R. Dec. 6, 1949 [Dec. 8, 1948], No. 31226/49. Class 83 (iv). In a method of re-shaping a metal tube by applying pressure to the end of the tube and to a plastic filler therein, one portion of the tube being closely embraced by a corresponding portion of a die and the other portion of the tube being open to a shaping cavity in the die, the pressures are separately applied to the tube end and to the filler in such a manner that the end of the tube and the end of the filler move at different rates. The rates of movement of the tube and of the end of the filler may be such that the change of surface area of that portion of the tube within the die cavity corresponds with the rate of feed of the filler thereinto. One of the pressures may be applied both to the tube end and to a portion of the end of the filler at such a rate of movement of the tube end as to correspond with the increasing surface area of that portion of the tube within the cavity of the die. A metal tube 1 filled with a plastic filler 2 such as lead, Woods metal or a similar alloy is placed in a die formed with a spherical cavity 4 and pressure is applied axially to both ends of the tube 1 and of the filler 2 by plungers 7, 8 and 9, 10. The two members of a pair of plungers approach each other at the same speed but the speeds of the different pairs depend upon the increase in surface area of the expanding part of the tube 1 and the volume of filler 2 required as the tube 1 takes up the shape of cavity 4. Arrangements operating with opposed plungers and with a single set of plungers arranged at one end of the tube are described for producing T-shaped and sphericallyended articles. In the arrangement for producing T-shaped articles shown in Fig. 10 plungers 24, 25 are hydraulically operated by passing a fluid through pipes 37, 36 to exert a pressure on pistons 34, 31. Valves in pipes 36, 37 control the rate of fluid flow into cylinders 30, 33 and hence the rate and amount of forward movement of plungers 25, 24. Springs 32, 35 return the pistons 31, 34 to their normal inoperative position when the valves in pipes 36, 37 are closed and valves in the fluid return pipes 38, 39 are open. Specifications 440,601 and 457,370 are referred to.