GB836125A - Apparatus and method for forming close tolerance tubing and articles therefrom - Google Patents

Abstract

836,125. Stretching; spinning. POWELL, V. R. May 31,1956 [May 31, 1955], No. 16881/56. Classes 83 (2) and 83 (4). Tubing is stretched beyond its yield point to decrease its wall thickness, the stretching force being applied to the ends of the tubing. Tubing T to be transformed to close tolerance tubing has its flared ends 124, 124<SP>1</SP> gripped in carriages 52, 86 respectively. A piston 82 in an hydraulic cylinder 80 then advances a mandrel 58 into the tube T. A piston 94 in an hydraulic cylinder 38 then moves the carriage 86 outwardly first to tension the tubing T, and then to stretch the tubing T permanently until its side walls have thinned to the desired extent. Supports 16 and 18 for the carriage 52 and the cylinder 38, respectively, are held rigid during stretching by admitting pressure liquid to bellows-like vessels 30, 40 connected to the supports. After thinning the tube walls and before removal of the tube, the exterior surface thereof may be engaged by a sizing die 108, on a carriage 102, moved along the tubing. The tubing ends may alternatively be held in their supports by internal and stub mandrels 170, 170<SP>1</SP>, Fig. 4, and split jaws 172, 172<SP>1</SP>. Instead of the stub mandrel 170 an elongated mandrel may be used, in which case the sizing die 108 may be used. Measuring means, Fig. 11 (not shown), for the outside of the tube may be provided which, through servo mechanism, moves a housing 158 of the sizing die 108 vertically or horizontally in its carriage 102 to correct for any variations in wall thickness. To form tubing with a tapered bore two pressure members 190, Fig. 10, move the stretched tubing inwardly on to a tapered mandrel 58<SP>1</SP>. The pressure members besides moving inwardly and longitudinally may also rotate around the tubing T. Alternatively, the tubing may be tensioned until its internal diameter has decreased to that of the smaller end of the tapered mandrel. The die 108 may be rotated around the tubing T or the tubing may be rotated relative to the die 108 or the members 190. Tube expanders. A mandrel 58 with a tapered head 58c, Fig. 12, may be passed through the tubing T being backed on the outside of the tubing by tapered pressure rollers 206 which may be rotated therearound. Making turbine blades; twisting; stamping. Tubing 230, Fig. 13, with a mandrel 232 disposed therein and gripped at one end 230a by jaws 234 and at the other end 230b by jaws 236, is twisted and stretched to conform to the shape of the mandrel 232 by jaw assemblies 234, 236. The mandrel 232 and stretched tubing are then placed between die members 222, 224, hinged together at 226, which are then closed. The formed tubing is then removed, surplus material 240 is cut off, and edges 242 are welded together. To form a blade having one wall of greater thickness, tubing with one section suitably thickened is used. Tubing of non-circular section may be used.