GB854534A - Improvements relating to the manufacture of butted tubes - Google Patents

Abstract

854,534. Drawing; separating mandrels from work; tube expanders. REYNOLDS T. I. ALUMINIUM Ltd. April 7, 1959 [April 17, 1958], No. 12262/58. Classes 83 (2) and 83 (4). In a method of making butted tubes, i.e. tubes with local thickening, a tube 11, Fig. 1, is first passed together with a mandrel 12 having end-portions 12a of reduced diameter, through a die 15 so that the tube wall conforms to the shape of the mandrel, the tube then being loosened by pinch rolls 16 prior to stripping from the mandrel by arresting the movement of either the mandrel or the tube. The tube 11 is pulled through the die 15 by jaws 14, the tube being stripped after completely passing the die by the continued movement of the jaws 14 while the mandrel 12 is held stationary by the engagement of a head 13 with the die, Fig. 3. The stripping movement causes the intermediate part of the mandrel to expand the thickened trailing end of the tube so that a butted tube, as shown in Fig. 5, is produced. If internal thickening is required at both ends, the tube of Fig. 5 is passed while unsupported internally through a die of similar diameter to that of the die 15. If external thickening is required at both ends the leading end of the tube is expanded by a plug 18 while held against an abutment 19, Fig. 8 (not shown). Local thickening may also be provided intermediate the ends of the tube in a similar manner using an intermediate reduced mandrel portion 12c, Fig. 9 (not shown). In a modification the tube and mandrel may be pushed through the die, the mandrel being stripped by retrogressive movement, while the tube is held stationary by a U-shaped member which is introduced over the mandrel and which bears against the die or diecasting.