Patent ID: 6460391
Filing Date: 2002-10-08
Classification: B21D

Abstract:
In a machine for stretching sheet metal beyond its elastic limit to level the sheet metal, said machine having a first jaw provided with a gripping surface, and a second jaw having a gripping surface which is presented toward the gripping surface of the first jaw, one of the jaws being capable of moving toward the other jaw to clamp the sheet metal between the gripping surfaces of the two jaws and exerting enough force on the sheet metal to prevent the sheet metal from slipping between the gripping surfaces of the jaws when a stretching force is applied to the sheet metal at the jaws, the second jaw including a bearing block having a backing surface that is presented toward the gripping face of the first jaw, the second jaw also including a gripping pad having a back face that is presented toward the backing surface of the bearing block, the gripping pad being formed from metal, the gripping surface of the second jaw being on the gripping pad where it is presented away from the back face of the pad and toward the gripping surface of the first jaw, the improvement comprising a shim located between backing surface of the bearing block and the back face of the pad, the shim being narrower than the back face of the pad and set inwardly from the sides of the back face on the pad, so as to cause the pad, at the gripping surface on the pad to assume a slightly convex configuration between the sides of the gripping surface when the jaws are forced together with the gripping surfaces bearing against the sheet metal.