The Study Of Influence Of Rigidity Of Servo System In NC Machine On Positioning Precision

Modern numerical control machine trends toward to high precision , high speed, the structure is request more and more appropriate. The performance ,precision and efficiency tend towards advance, too. Especially, the requirement for machine tool servo system has been more and more higher. The performance index of servo system in NC machine can summary to: high precision, quick-response, stabilization. Obviously, positioning precision of the NC machine is the important guideline to judge the performance .The influence factor of the positioning precision are multiform, rigidity of the feed system is the uppermost Therefore, study for influence of rigidity of feed system in NC machine on position precision have very signification.In the paper, have studied the rigidity and the position precision. The influence factor of the rigidity and the position precision have educed. After then, have analysed the influence of rigidity on position precision, and put forward the improvement measure of rigidity and position precision. Including:1. Divide the NC feeding system into servo drive module and machine drive module. Parted create the servo drive system mathematic model and the actuating mechanism dynamic model and mathematic model. Educed the transfer function, then association with the transfer function of the feed system.2. The rigidity of the feeding system can divide into mechanical rigidity and servo rigidity and then analysed them. The structure and parameter of function unit in the feed system have been educed, and the regular pattern too, and then put forward the improvement measure of rigidity.3. According to the created model of the feed system. The steady error that create in feed system when input position signaling and rate signal, and the position error when open loop and close loop in the feed system. Working-out the servo error expression of the feed system in close loop, and analysed the expression.4. Study for influence of rigidity of feed system on position precision in open loop and close loop. The servo statically rigidity error has been study emphasis, and put forward the method to eliminate the servo statically rigidity error by taking the feedforward control. The validity of this method has proved by simulink simulation.