GB838632A - Stretching machines - Google Patents

Abstract

838,632. Stretching. HYDRAULIK G.m.b.H. Jan. 31, 1958 [Feb. 2, 1957], No. 3313/58. Class 83 (4). Apparatus for stretching metal sheet includes crossheads, for gripping the ends of the sheet, which are pushed apart, to stretch the sheet, by hydraulic means between the crossheads acting on pressure members which extend from the hydraulic means to each crosshead. Crossheads 1, slidable on carriages 2, 27, on rails 3, are pushed apart to stretch a sheet held therebetween by pistons 6, 7, in cylinders 4, 5, acting on pressure members to each side of, and in the plane of, the sheet in the forms of distance pieces 9, 10 pressing through ball cups 13 on lateral lugs 1a of the crossheads 1. The distance pieces, which may be in the form of cast pipes, are supported by rollers 11 running on rails 12. The crossheads 1 are adjustable towards one another by rods 14 of pistons 15 in cylinders 16. If a sheet breaks a piston 18 in a cylinder 19, normally held against a stop 20 at the end of the cylinder 16 by air pressure from a container 17, is forced back by the shock. Each crosshead comprises spaced sets of laminations 1b, 1c, arms 23 with inclined surfaces, and jaws 21 moved by rods 22 to slide on the inclined surfaces to grip the sheet. The arms 23 are enclosed by a frame comprising upper and lower beams 24 spaced apart by members 25 and held together by rings 26 shrunk on. To stretch short sheets of a length L2, Fig. 1, the distance pieces 9, 10 are dispensed with and the pistons 6, 7 act directly on the lugs 1a of the crossheads. Each pair of cylinders 4, 5 may be formed as one and a separating plate 8 between the cylinders omitted.