The accuracy trouble shooting of CNC machine tools is difficult to be repaired in the case of machine faults. The main performance of the machine tools is the size accuracy of the parts machined by the machine tools and the position accuracy that can’t meet the requirements. The process of repairing CNC machine fault is more complex, so we need a comprehensive analysis from the CNC system, servo system, mechanical parts and process etc., and put forward the testing scheme. Through the analysis of the measured data, the fault location of the machine tool is confirmed, and the accuracy is detected at the repair fault location.
1. Machine tool fault phenomenon
We encountered a CNC lathe accuracy failure. The outer and inner hole machining size is not stable, it may have fault when processing beyond the range of 2mm; axial size parts are beyond the range of a 0.5mm.
The numerical control lathe is not accurate and also random, and the size distribution of the machined parts is scattered. Analyze the process of the defective parts. The parts are clamped with a hydraulic chuck. Firstly, you should process the end face, then the outer circle, and finally the inner hole.
2. Electrical system analysis
The machine tool uses the SIEMENS 802D CNC system, and the machine tool is a half closed loop system. In the process of machining parts, CNC system does not produce alarm and information. There are no problems with setting the parameters of the system (pitch compensation, backlash, etc.).
Servo motor, servo motor encoder detection: the disintegration of detecting the motor tail of the encoder, found no encoder connection part failure; found no fouling by measuring encoder; normal oscilloscope signal encoder. Motors and encoders are normal.