Patent ID: 6189364
Filing Date: 2001-02-20
Classification: B21D,B30B,G05B

Abstract:
A bend angle correction method for correcting a bend angle when bending a workpiece by the cooperative movement of a movable die and a fixed die, the movable die being driven at shaft-load imposed points, for penetration, by three or more drive shafts, and the fixed die being disposed in an opposing relationship with the movable die, comprising:(a) providing memory means, and storing in said memory means workpiece bending conditions, workpiece target bend angle to springback angle relationship data and workpiece bend angle to movable die penetration amount relationship data;(b) providing measuring means and measuring the bend angle of the workpiece during bending operation and obtaining the difference between a target bend angle and the measured bend angle at at least three points, that are, each end and a center of the workpiece;(c) providing calculating means, and calculating with said calculating means, a provisional penetration point of the movable die associated with each drive shaft, based on the workpiece bending conditions and the workpiece target bend angle to springback angle relationship data which are stored in the memory means, and calculating a corrective penetration amount of the movable die associated with each angle measuring point, based on the bend angle of the work piece measured by the bend angle measuring means when each provisional penetration point has been reached and based on the workpiece target bend angle to springback angle relationship data and the workpiece bend angle to movable die penetration amount relationship data which are stored in the memory means;(d) providing interpolating means and obtaining, by interpolation, a final penetration point of the movable die associated with each shaft-load imposed point of the movable die, from the corrective penetration amounts calculated by the calculating means; and(e) driving the movable die, with use of the die driving means, until each shaft-load imposed point of the movable die reaches its final penetration point, after driving it until each shaft-load imposed point reaches its provisional penetration point.