Patent ID: 7673377
Filing Date: 2010-03-09
Classification: B21J,Y10T

Abstract:
1. A method for insertion of a fastener into a workpiece in which rotational movement of a screw member with a longitudinally extending circumferential thread is converted into linear movement of a fastener insertion actuator assembly via intermediate rolling transmission elements disposed between the thread of the screw member and a circumferential surface of the actuator 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 the energy required to insert the fastener into the workpiece to a desired depth; (b) determining from the mass moment of inertia of the screw member, an angular velocity of the screw member required to achieve a kinetic energy level of the screw member and drive system that is sufficient to deliver the determined energy to the fastener; (c) positioning a fastener for insertion into the workpiece; (d) 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 (e) 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 determined angular velocity either before or during a period when the actuator assembly comes into contact with the fastener so as to transfer the kinetic energy of the rotating screw member into work done in inserting the fastener into the workpiece.