Maintenance of Abnormal Accuracy Fault of CNC Machine
Computer Numeric Control (CNC) technology is widely used in all kinds of automatic machining. CNC machines are recognized as precision machines in the manufacturing industry due to their high machining accuracy and repeatability. However, when many users process the parts and use CNC machines, they will find that their machined accuracy is abnormal, which is a common abnormal fault of CNC machine tool processing. This explains why we should properly understand and deal with the abnormal accuracy fault of CNC machine tools.
The first type of abnormal accuracy fault of CNC machine tools is positioning accuracy fault. This fault is characterized by low positioning accuracy, poor B-axis accuracy, drill bit skidding, and incorrect machining depth. Generally, the reasons for this kind of accuracy fault are as follows. On the one hand, the quality of the machining program is poor, and the position and shape of the tool can not match the machining accuracy requirements of the part. On the other hand, the linear guidance and circular guidance of the machine tool are worn, the accuracy of the mechatronics is low, and the structure parameters of the machine tool and the coordination accuracy between the spindle axis and the table are not correct. To solve the positioning accuracy fault, appropriate measures should be taken to improve the quality of the machining program, check and adjust the accuracy of the machine tool, and repair or replace the worn components.
The second type of CNC machine tool accuracy anomaly is machining accuracy fault. This fault is characterized by small machining accuracy, rough surface, out-of-shape profile, and obvious vibration. In general, the machining accuracy of CNC machine tools is mainly determined by the design of fixtures, the accuracy of the tool and tool holder assembly, the performance of the tool, the structure parameters of the machine tool, the cutting parameters and cutting speed. To solve the machining accuracy fault, we should solve the problems existing in the tool, tool holder and fixture, take proper control of the cutting parameters, use the appropriate cutting speed to ensure the quality of the machined surface and profile, and adjust the accuracy of the machine tool.
In addition, the bending of the line connected to the servo motor, the looseness of the connection parts between the ball screw and the motor axis, the looseness of the fixing screw of the servo motor and its mounting seat, and the loosening of the electrical connection part can also lead to accuracy fault of CNC machine tools. Furthermore, diversified increase, diversified decrease and diversified range can cause thickness difference of cutting pieces and machining speed anomalies. In this case, we should first check the connection parts between the servo motor and the axis, and adjust the roundness and concentricity of the run-out. Then, we should check the positioning accuracy of the screw and use special tools to measure them. Finally, check the electricity connection part of the machine tool and make corresponding measures.
In conclusion, the abnormal accuracy fault of CNC machine is mainly caused by the poor program quality, the low accuracy of mechatronics, the structural parameters error and the wear of the machine. In order to solve this kind of fault, we should use proper measures to improve the quality of the machining program, check and adjust the accuracy of the machine tool accordingly, and repair or replace the worn components of the machine. It is hoped that the fault can be avoided in operation and the machining accuracy of CNC machine tools can be improved.
