Method of bending a metal plate

Abstract

A plate workpiece having an edge is bent with a press having a stationary upper die with a lower face and a vertically and horizontally movable lower die with an upper face. With the upper face of the lower die spaced below the lower face of the upper die, the workpiece is fitted between the dies such that the edge of the plate bears in a horizontal direction on the upper face of the lower die and an upper face of the plate bears upward on a portion of the lower face of the upper die. Then the lower die is moved vertically upward toward the upper die at a predetermined vertical rate while the lower die is shifted horizontally synchronously in the direction at a predetermined horizontal rate such that the plate edge engaging the lower-die upper face does not shift there along during upward movement.

1 . A method of deforming a plate workpiece having an edge with a bending press having a stationary upper die with a lower face and a vertically and horizontally movable lower die with an upper face, the method comprising the steps of:
 with the upper face of the lower die spaced below the lower face of the upper die, fitting the workpiece between the dies such that the edge of the plate bears in a horizontal direction on the upper face of the lower die and an upper face of the plate bears upward on a portion of the lower face of the upper die; and   synchronously moving the lower die vertically upward toward the upper die at a predetermined vertical rate while shifting the lower die horizontally in the direction at a predetermined horizontal rate such that the plate edge engaging the upper face does not shift along the upper face during upward movement.   
     
     
         2 . The method defined in  claim 1  wherein the upper and lower faces are complementary and the lower die is shifted upward until the workpiece is held in surface contact with both faces. 
     
     
         3 . The method defined in  claim 2  further comprising the step of
 holding the plate between the faces after the workpiece is in surface contact with both faces. 
 
     
     
         4 . The method defined in  claim 1  wherein the lower face is downwardly convex and the upper face is upwardly concave. 
     
     
         5 . The method defined in  claim 4  wherein the curvature of the lower face is not constant. 
     
     
         6 . The method defined in  claim 4  wherein the curvature of the upper face is not constant. 
     
     
         7 . The method defined in  claim 1 , further comprising the step of
 clamping the plate against horizontal movement after the edge contacts the upper face and during upward movement of the lower die.   
     
     
         8 . The method defined in  claim 1  wherein the press includes a controller that sets the rates in accordance with a stored correlation between the vertical rate and the horizontal rate.