Design Of Hydraulic Servo Control System For Phase Friction Welding

Friction welding is a kind of technology that applying appropriate axial pressure on therelative surfaces of two welding parts which are rotating at a high speed, so that generatingthe friction heat to weld. However, if there is a requirement of welding phase between twowelding parts, how to control the relative phase accurately will be a problem to be solved,therefore phase friction welding (PFW) machine emerges as the times require.Firstly, the development of friction welding at home and abroad has been introduced.The basic working principle of PFW has been analysed through the research on frictionwelding to make clear that the most difficult problem of PFW is how to check out theaccurate rotational speed and get the right relative phase to stop rapidly. Accordingly, anovel method of phase control accurately based on hydraulic servo system has been putforward in this paper. The C8051F020single-chip microcomputer has been selected as thecore control element, the absolute encoder as the core feedback element, the hydraulicsystem as the actuating mechanism. Also the fuzzy PID control method with doubleclosed-loop of speed and position has been adopted.Afterwards, corresponding hydraulic system and control circuit have been designedaccording to the control scheme, the selection of hydraulic components and the productionof the PCB board have been completed in the paper. Then the feasibility and stability ofcontrol system have been confirmed theoretically with the simulation of Matlab. On thebasis of that, the influence on the control system of materials of welding parts has beenresearched.Finally, after days of test, the control scheme has been verified as correct again,achieved good results, and some suggestions to the problems meet in the test andimprovements of the control scheme have been proposed based on that. In fact, the controlscheme in the paper owns more advantages comparing with conventional friction weldingmachine which adopting relay control system: the control precision is higher, the equipmentis more simple and reliable, the operation is safer, more convenient and flexible, mostimportantly, it costs less.