GB844897A - Stretching machines - Google Patents

Abstract

844,897. Stretching. HYDRAULIC G.m.b.H. Jan. 31, 1958 [March 7, 1957], No. 3358/58. Addition to 838,632. Class 83 (4). Apparatus for stretching metal sheet includes crossheads, for gripping the ends of the sheet, one of which cross-heads is pushed away from the other, to stretch the sheet, by hydraulic means between the cross-heads, the movable part of the hydraulic means acting through pressure members which extend from the means to the movable cross-head, pressure members also extending between the stationary cross-head and a stationary part of the hydraulic means to take up reaction. Cross-heads 1, 2 are mounted on carriages 3 running on rails 4 and the head 1 is pushed away from the head 2 to stretch the sheet by pistons 6 in cylinders 5 acting through pressure members 7, pressure members 8 between the cylinders 5 and the head 2, which is stationary during stretching, taking up the reaction. The pressure members 7, which merely abut against the pistons 6 and are supported on carriages 11, may be angularly grooved adjacent the crosshead 1 which grooves are engaged by half-nuts 9 pivoted at 10 to the cross-head to lock the head in its adjusted position on the pressure members 7, extensions of the pressure members passing through holes in the cross-head. Alternatively the pressure members may be helically grooved or annularly grooved with longitudinal grooves also and engaged by nuts, also annularly and longitudinally grooved, locked on the pressure members by rotation, or notched and locked to the head by parts engaging the notches. The cylinders 5 are not anchored to the bed of the machine and the pressure members 8 abut stops 12 thereon and engage stops 13, each in the form of two pivoted halfcylindrical members, on the head 2. The crossheads are adjustable towards one another by piston rods 14 having pistons 15 in cylinders having a buffer piston 18 pressed against a stop 20 by a column of liquid loaded by compressed air from a container 17, such pressure being overcome if the sheet breaks. When used for stretching the shortest sheets the piston 6 and cylinder 5 bear directly on the nuts 10, 13 on the cross-heads, the pressure members passing through apertures in the cross-heads. The pressure members 7, 8 may each be in the form of a number of abutting distance pieces.