Control of linear friction welding

Linear friction welding is a relatively new method of joining materials. It is a solid state joining technique, in which significant heat is generated at the faying surfaces of two components under a certain combination of pressure, amplitude and frequency of the relative linear motion. In particular one process, linear friction welding, can be used to join of complex profiles. The linear friction welding process is extremely fast, the whole process could last for several seconds and the control of energy and time parameters is only possible in automatic mode. This paper describes a control system of the linear friction welding mashine. The system is based on a servo-hydraulic testing machine "Schenck", computer and a microcontroller. The linear friction welding cycle consists of compressing two samples to be welded, turning on and off vibrations at a given frequency and amplitude and creation of forging force. The key elements of the welding machine are vibration and compression hydraulic cylinders. The control system synchronizes these hydraulic cylinders and ensures that the linear friction machine operates during the whole welding cycle automatically with pre specified parameters. The control systems of hydraulic cylinders are interconnected and connected with computer via microcontroller. The changes in the burn-off and the friction force are recorded in real time. Desirable levels of precision of the burn-off and the strength of the joint are achieved. We performed several experiments with different materials.