Apparatus and method of compensating for springback in a workpiece

Claim 3

The method of claim 1, wherein said step of sensing the cessation of springback motion includes the substep of selectively activating a means for sensing a neutral position of said workpiece when the movement of said punch member changes from said first direction to said second direction.

Claim 4

A brake press for bending a workpiece to a predetermined angle, wherein springback of the workpiece is automatically compensated for by overbending the workpiece by a calculated amount, comprising: a pair of spaced die members for supporting said workpiece while said workpiece is being bent therebetween; a punch member, and means for moving said punch member in a first direction into said cavity to bend said workpiece, and for moving said punch member in a second direction, opposite said first direction, to permit said workpiece to springback; means, positioned in opposition to said punch member, for sensing the speed of movement of said workpiece in said second direction during springback thereof, for sensing a neutral position of said workpiece corresponding to the cessation of springback motion in the workpiece, and for generating signals in response thereto, said sensing means being biased toward said workpiece and said means for moving the workpiece being responsive to said signals to cease movement of said punch member in said second direction; means for controlling the speed of movement of said punch member in said second direction in accordance with said signals generated by said sensing means; and means, responsive to the signal generated by said sensing means, for determining the linear distance of springback in said workpiece corresponding to the distance said punch member moves in said second direction, and calculating, based on said linear distance of springback and the physical geometry of said brakepress, an amount of overbend required to achieve said predetermined angle of bend in said workpiece after springback.

Claim 5

A brake press for bending a workpiece to a predetermined angle, wherein springback of the workpiece is automatically compensated for by overbending the workpiece by a calculated amount, comprising: a pair of spaced die members for supporting said workpiece while said workpiece is being bent therebetween; a punch member, and means for moving said punch member in a first direction into said cavity to bend said workpiece, and for moving said punch member in a second direction, opposite said first direction, to permit said workpiece to springback; means, positioned in opposition to said punch member, for sensing the speed of movement of said workpiece in said second direction during springback thereof, for sensing a neutral position of said workpiece corresponding to the cessation of springback motion in the workpiece, and for generating signals in response thereto, said sensing means being biased toward said workpiece and said means for moving the workpiece being responsive to said signals to cease movement of said punch member in said second direction; means for controlling the speed of movement of said punch member in said second direction in accordance with said signals generated by said sensing means; and means, responsive to the signal generated by said sensing means, for determining the linear distance of springback in said workpiece corresponding to the distance said punch member moves in said second direction, and calculating, based on said linear distance of springback and the physical geometry of said brakepress, an amount of overbend required to achieve said predetermined angle of bend in said workpiece after springback.

Claim 6

The brakepress of claim 3, further including means for generating a signal when movement of said punch member changes from said first direction to said second direction, said signal to selectively activate said means for sensing the neutral position of said workpiece.

Claim 7

The die press of claim 3, wherein said sensing means comprises a linear variable differential transformer having a movable cord rod axially biased toward said workpiece.

Claim 8

The die press of claim 5, wherein said means for determining the linear distance of springback includes means for measuring the distance of said punch member moves in said second direction.

Claim 9

The die press of claim 5, wherein said means for determining the linear distance of springback includes means for monitoring and recording the position of said core rod.