Fast response weld head

Abstract

A fast response weld head which employs a control system to allow user control of critical welding parameters such as speed, force, position, and duration. In one embodiment, the control system includes a position servo loop attached to a motor driven output shaft on which a welding electrode is mounted utilizing a follow-up spring assembly. During a weld cycle, the control system moves the welding electrode toward a workpiece at a rapid user-defined rate. Just prior to when the electrode is reduced to prevent damage to the parts. When contact is made, the force exerted by the electrode on the workpiece is measured until the measured force equals a user-defined optimum welding force. A user-defined weld current is enabled to the electrode. When the weld is complete, the welding electrode is automatically raised by the control system, releasing all pressure on the workpiece. In a second and presently preferred embodiment, a linear magnetic actuator is utilized in lieu of a motor to drive the output shaft. The follow-up spring assembly is eliminated. The force required to keep constant pressure on the weld is now provided by programming the linear actuator to exert a very short pulse of force to maintain constant pressure on the weld as the weld softens at the onset of applications of weld current. Force is then returned to normal force until the weld is complete.