Electromagnetic bounce back braking for punch press and punch press process

摘要

A method of punching a via or through hole in a polymer-metal laminate workpiece in a punch press. The punch press has a punch tool, a driver coil for driving the punch tool through the polymer-metal laminate workpiece, and a stopper for stopping the punch travel of the punch tool and mechanically returning the punch tool to its starting position. The method includes the steps of applying an electrical current pulse through the driver coil to electromagnetically drive the punch downward to and through the workpiece, and then elastically colliding the punch tool with the stopper to stop and return the punch tool on an upward return stroke. Subsequently a second, braking pulse is applied through the driver coil to electromagnetically brake the punch. The second electrical current is applied after the start of the punching pulse, for a time and magnitude sufficient to brake the punch press.