Patent GB-858795-A (GB)
Title: Improvements in and relating to stretching machines for flat metal articles
Inventor: ALBERS HEINRICH BERNARD
IPC: B21D25/00
Filed: 1955-12-05
Abstract: 858,795. Stretching. BALDWIN-LIMAHAMILTON CORPORATION. Feb. 28,1957 [Dec. 5, 1955], No. 34785/55. Class 83 (4). A horizontal machine for stretching metal sheet having a pair of gripping heads supported on said frame for relative movement longitudinally thereof, and means for applying pressure to move said gripping heads away from each other is characterized in that each gripping head has an upper section and a separate lower section, each section being composed of a plurality of vertical laminations and means interconnecting each upper section and the respective lower section. A sheet to be stretched is gripped adjacent its ends in gripping jaws 10, 10<1> of spaced gripping heads 20, 20<1> supported on slides 11, 111 on fixed rails 12, 121, the head 20 being adjustably secured to longitudinal girders 34, 35 by pins 30 carried by the head and lockable in holes 31 in the girders and the stretching force being applied by the other head 20<1>. Fluid pressure cylinders 41, 42, 43 are mounted on a lug 60 on one side of a crosshead 901 rigid with the gripping head 20<1> and fluidpressure cylinders 44, 45, 46 are mounted on a lug 61<1> on the other side of the crosshead 90<1>, the pistons of these cylinders being fixed in stationary crosshead 50, 51 attached to the girders 34, 35. The pistons of the cylinders 42, 45 are also secured to a fixed frame 66. The head 20<1> may be returned by pneumatic pressure operating upon pistons 70, 71, secured to the crosshead 901 of the head 20<1>, operating in cylinders 72, 73 fixed in the frame 66, such pistons also acting to cushion shock if the sheet being stretched should break. The gripping heads 20, 201 each comprise an upper section 80 or 801 and a lower section 81 or 81<1>, each section being composed of a plurality of spaced laminations 82, 83, 821 or 831, the spaces between the laminations being filled by links 84, 85 for the head 20 and 84<1>, 85<1> for the head 20<1>, the laminations and links being connected by tubular pins 86, 86<1> about which the sections tend to pivot under stress. The crosshead 90<1> is secured to the links 85<1> and a similar crosshead 90 for the head 20 is secured to the links 85. The jaws 10, 10<1> in the heads 20, 201 are closed by linkages 100, 100<1>. The locating pins 30 of the crosshead 20 are in the form of cylinders movable into or out of the holes 31, in upper and lower arms 97 of the U-shaped girders 34, 35, by fluid-pressure admitted through pistons 102, 103, carried by the crosshead 90, on which the cylinders slide. To adjust the position of the head 20 there are provided two rods 110 secured one to each side of the crosshead 90 and to a cylinder 112 movable on a double-acting piston 114 which is releasably locked to the girders 34, 35 by fluid-pressureoperated members 115, 116 adapted to engage the holes 31. To move the head 20 a distance greater than the stroke of the cylinder 112, the members 115, 116 are withdrawn from the holes 31 and the pistons 114 are withdrawn into their cylinders 112. The members 115, 116 are then moved outwardly to engage new holes 31. Specification 858,796 is referred to.