Patent ID: 7908727

Claim:
A panel clinching method wherein a workpiece including two or more sheets of material are deformed into locking engagement, the deformation resulting from the driving of a punch of fastening apparatus, the sheet material being disposed between a nose and a die of fastening apparatus, in which rotational movement of a longitudinally extending screw member is converted into linear movement of an actuator assembly by intermediate rolling transmission elements disposed between a thread of the screw member and a threaded circumferential surface of the actuator assembly so as to be in rolling contact with both, the screw member being driven in rotation by a drive system, the method comprising the steps of: (a) determining an energy required to deform the material; (b) determining a required angular velocity of the screw member to achieve a kinetic energy level of the screw member and drive system that is sufficient to deliver the determined energy to the actuator assembly; (c) controlling the drive system so as to accelerate the screw member to an angular velocity in excess of the determined angular velocity, the rotation of the screw member effecting simultaneous linear movement of the actuator assembly towards the workpiece; and (d) thereafter controlling the drive system so that it acts as a brake on the screw member thereby decelerating the screw member until it reaches substantially the required angular velocity either before or during a period when the actuator assembly comes into contact with the workpiece so as to transfer the kinetic energy of the rotating screw member into work done in deforming the workpiece.