Troubleshooting of CNC machine tools

Troubleshooting of CNC machine tools
In CNC machine tools, most of the faults have data to check, but there are also some faults that provide vague or even no alarm information, or have a long, irregular, and irregular occurrence period, which brings many difficulties to search and analyze. For this type of machine tool malfunction, it is necessary to analyze the specific situation and patiently search for it. Moreover, comprehensive knowledge in mechanical, electrical, hydraulic, and other aspects is particularly needed during inspection, otherwise it is difficult to quickly and correctly find the true cause of the malfunction.
Abnormal machining accuracy faults: Changes or modifications in system parameters, mechanical faults, non optimization of machine tool electrical parameters, abnormal motor operation, abnormal machine tool position loop, or improper control logic are common causes of abnormal machining accuracy faults in CNC machine tools during production. By identifying and handling relevant fault points, the machine tool can be restored to normal. In production, abnormal machining accuracy faults of CNC machine tools are often encountered. This type of fault has strong concealment and is difficult to diagnose.
There are five main reasons for such failures:
1. The feed unit of the machine tool has been modified or changed;
2. The null offset of each axis of the machine tool is abnormal;
3. Abnormal axial reverse clearance (BackLASH);
4. Abnormal motor operation status, i.e. electrical and control faults;
5. Mechanical failures, such as screws, bearings, couplings, and other components.
In addition, the programming of machining programs, the selection of cutting tools, and human factors may also lead to abnormal machining accuracy.
Abnormal machining accuracy caused by mechanical faults should be checked one by one in the following aspects.
1. Check the machining program segment that is running when the machine tool accuracy is abnormal, especially for tool length compensation, calibration and calculation of the machining coordinate system (G54~G59).
2. In the jog mode, the Z-axis is repeatedly moved, and through visual, tactile, and auditory diagnosis of its motion status, it is found that the Z-axis movement sound is abnormal, especially during rapid jog, and the noise is more pronounced. From this judgment, there may be hidden dangers in the mechanical aspect [1].