Diagnosis and Treatment of Abnormal Processing Precision of CNC Machine Tools
Abstract
This paper analyses the causes of the fault of processing precision of CNC machine tools, expounds the principle of fault diagnosis, and puts forward the basic methods of fault treatment. Through this investigation, we can figure out a better way to diagnose and process the fault of processing precision of CNC machine tools, so as to improve the accuracy of CNC machine tools.
Key words: CNC machine tool; processing precision; fault diagnosis; fault processing.
1 Introduction
NC machines can process complex curves and complex 3D shapes in batches. It is widely used in processing spare parts in automobile, aviation and other fields, playing a very important role in quality improvement of finished products. Therefore, it is necessary to make sure that NC machines have high-precision processing capability.
2 Reasons of Fault of Processing Precision of CNC Machine Tools
2.1 The processing capacity of CNC machine tool is not enough, resulting in inaccuracy
CNC machine tools are select, assemble and adjust the speed according to their own capacity. Improper assembly and adjustment, overload operation, insufficient lubrication and other reasons will cause the overload of machine tools, resulting in poor processing accuracy.
2.2 The installation accuracy of CNC machine tool is not enough, resulting in inaccuracy
The installation accuracy of CNC machine tool is the key to ensure its accuracy. If the machine tool has insufficient accuracy in the overall installation and adjustment, the accuracy of the processed parts will be affected. Therefore, the installation accuracy of CNC machine tool is especially important.
2.3 The coordinate frame of CNC machine tool has error and the backlash of screw thread is large
If there is too much play on the coordinate frame of CNC machine tool or the lead screw has a large axial backlash, the accuracy and repeatability of the processed parts will be affected.
2.4 The tool holder and knife is not installed correctly
The tool holder and knife should be installed correctly according to the tool selection, which is related to the processing accuracy of parts. If the knife is not normal and the knife holder is installed incorrectly, it will cause the processing accuracy to be low.
2.5 The automatic tool exchange system is faulty
The automatic tool exchange system can not be operated normally, leading to the deviation of the cutting tool position. If the position of the cutting tool is deviated during machining, the accuracy of the machined parts will also be affected.
3 Principle of Fault Diagnosis
3.1 High-precision measurement should be carried out
First of all, it is necessary to measure the coordinate accuracy of the machine tool by means of specific high-precision measuring instruments, so as to analyze whether the machining accuracy is affected by the inaccuracy of the machine itself.
3.2 Check the tightness and installation of parts
Check the tightness and installation of transmission parts of CNC machine tool to see if it is the problem of installation accuracy.
3.3 Exclude geometric error
By excluding linear and angular errors and wear of parts, corresponding measures can be taken to improve machining accuracy.
3.4 Analyze the surface accuracy of the workpiece
When the measurement indicates that the accuracy of the workpiece is not enough, the following measures can be taken to analyze the machining accuracy: form linearly, roundness and the surface quality, etc., and the accuracy of each process can be determined.
4 Fault Treatment
4.1 Increase the lubrication and reduce the load
Reduce the load of bearing on the machine tool and ensure correct lubrication to prevent the bearing from overheating and affecting accuracy.
4.2 Check and adjust the installation accuracy
Check and adjust the installation accuracy of parts which affect accuracy and repeatability, and eliminate the dynamic error which affects accuracy and repeatability when running at the maximum speed.
4.3 Eliminate geometric errors
Eliminate the linear and angular errors of transmission parts of the machine tool, or replace the worn parts.
4.4 Adjust the tool balancing device
Adjust the balancing device on the tool side, and make sure that the tool can be balanced in all directions so as to reduce vibration.
4.5 Check the automatic tool exchange system
Check the automatic tool exchange system and adjust the knife so that the knife can move in the right direction and position.
5 Conclusion
This paper widely studies in detail the fault of processing accuracy of CNC machine tools, the principles of fault diagnosis and fault treatment, and puts forward some helpful suggestions. We should pay attention to the maintenance of CNC machine tools on a daily basis, find problems and solve them in time, so as to ensure the accuracy and quality of parts processing.
