GB810683A - Gripperhead for hydraulic stretching machines - Google Patents

Abstract

810,683. Stretching. LOEWY ENGINEERING CO. Ltd. Sept. 5, 1957 [Sept. 10, 1956], No. 27663/56. Class 83 (4). A gripperhead for an hydraulic stretching machine comprises a supporting structure for two co-operating gripping jaws constituted by two spaced-apart crossbeam units, one for each gripping jaw, said crossbeam units and said jaws being arranged in superposed relationship, and said crossbeam units extending across the width of the jaws and therebeyond so that they project with their ends beyond the ends of the jaws, and tie-rods extending between and connecting corresponding ends of the two crossbeam units so that the crossbeam units and the tie-rods form together a closed rectangular frame structure in which the jaws are accommodated. A gripperhead 1 is moved away from a gripperhead 2, to stretch metal sheet held therebetween, by hydraulic rams 4, at the ends of longitudinal compression members 5, engaging lateral extensions 3 of the gripperhead 1, auxiliary rams 4A returning the head 1. The gripperhead 2 is adjustably secured to the members 5 by locking pins engaging lateral extensions 8 of the head 2 and holes in the members 5. The gripperhead 1 comprises upper and lower crossbeams 9 for jaws 10, which jaws are displaceable by hydraulic means 12 fitted to the head 1 by rods 13. The crossbeams 9 project at 9A beyond the ends of the jaws and are there connected by tie-rods 11 having nuts threaded on their ends. The head 2 is of similar construction but formed with transverse extensions 8. In a modification of the gripperhead 1, Figs. 6, 7, inner crossbeam members 15 carry jaws 17 and outer crossbeam members 16, connected by tie-rods 18, bear against the inner members 15 at spaced points 19. An hydraulic unit 21 operates the jaws 17. The other gripperhead 2 is similar but provided with locking rods 23, Fig. 8 (not shown), to engage holes in compression members. The outer cross beams members 16 mav be in the form of laminated plates or in two halves interconnected by tierods. Groups of two or more tie-rods 11 or 18 may be provided at each end of the crossbeams. The tie-rods may be prestressed. The tie-rods may be formed at one or both ends thereof as an hydraulic ram entering a cylinder of pressure fluid.