Abstract: For controlling the quality of friction welding process, the computer closed loop control system with electron-hydraulic proportional valves is set up on the base of the primary load system with normal hydraulic valves. The electron-hydraulic proportional valves of pressure and flow are added. The correspond computer hard wares are configured. The control programs are wrote using VC++ on the windows operation system. The applications and tests on the static and dynamic state show that: this control system has good properties on the static and dynamic state, and have a high reliability. The axial pressure during friction welding can be close loop controlled. The moving speed of slipway can be proportionally controlled. The rotate speed, axial pressure, axial shorten, friction torque, as well as interface temperature, can be examined real time. This system could satisfy the need of closed loop controlled system of friction welding, and have a broad application foreground.

Key words: Electron-hydraulic proportional control, Auto control, Friction welding