The influence of geometric errors and working errors of lathes on machining accuracy makes the actual geometric parameters (size, shape, position) of the parts processed do not match the ideal geometric parameters, which affects the processing quality. Therefore, in machining, the error is inevitable, but the error must be within the allowable range. Through error analysis, grasp the basic law of its change, so as to take corresponding measures to reduce processing errors and improve processing accuracy. Processing errors are mainly divided into the following three types:
① Random error
Random error is the error in which the absolute value and sign cannot be changed predetermined when the same value is measured multiple times under the same conditions. There are many factors that produce random errors, and most of these factors are accidental and unstable.
②System error
System error refers to the error in which the size and sign of the error remain unchanged or change according to a certain rule when the same measurement value is repeatedly measured under the same conditions. That is, the former case is the fixed value system error, and the latter case is the straightening system error.
③Large error
Gross error refers to an error that exceeds expectations under specified conditions.
Preventive measures to reduce errors
1 Measurement method. The measurement method refers to the combination of the measuring instruments and measurement conditions used in the measurement. Before measurement, the best measurement method should be determined according to the characteristics of the measured object.
2 Measurement accuracy. Measurement accuracy refers to the degree of agreement between the measurement result and the true value. The accuracy of the effective value of the measurement result is determined by the measurement accuracy.
3 Reduce the original error. Improving the geometric accuracy used in part processing, improving the accuracy of measuring tools, fixtures and tools themselves, and controlling the force, thermal deformation, tool wear, deformation caused by internal stress, and measurement errors of the process system are all directly reducing the original error.
4 Transfer the original error. The essence of this method is to transfer the original error from the error-sensitive direction to the error-insensitive direction. Transfer the original error to the non-sensitive direction.
5 Differentiation of the original error. In order to improve the processing accuracy of a batch of parts, a method of differentiating some original errors can be adopted. For the surface of parts with high machining accuracy requirements, the method of gradually homogenizing the original error in the continuous trial cutting process can also be adopted.
6 Average the original error. The process of continuously reducing and averaging the original error of the processed surface through processing. The principle of homogenization is to find out the differences between closely related workpieces or tool surfaces through mutual comparison and inspection, and then perform mutual correction or benchmark processing.
7 Error compensation method. For some of the original errors of the process system, error compensation methods can be adopted to control its impact on the machining errors of the parts. This method is to artificially create a new original error, thereby compensating or offsetting the original original error inherent in the original process system, achieving the purpose of reducing processing errors and improving processing accuracy.
8 Error cancellation method. Use the original original error to remove part or all of the original original error or another original error.
In short, in lathe processing, errors are inevitable. As long as the causes of errors are analyzed in detail, tools, measuring tools, fixtures, measuring methods and related handles are adjusted to the best, and processing errors are minimized, so as to improve the lathe Machining precision, improve production efficiency, and process parts that meet the requirements of the drawings.
