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The method to ensure and improve the accuracy of cnc machining process

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Update time : 2018-02-23 15:34:38

In the machining process, there are often many factors that affect the final processing quality of the workpiece. How to make the quality of the workpiece processing requirements, how to reduce the impact of various factors on the processing accuracy, processing has become a matter that must be considered. In machining, the error is inevitable, but the error must be within the allowable range. Through error analysis, grasp the basic rules of its change, so as to take appropriate measures to reduce the machining error and improve the machining accuracy.
cnc machining accuracy
The method to ensure and improve the accuracy can be broadly summarized as the following:
1.Reduce the original error, improve the geometric accuracy of the machine tool used in the part machining, improve the accuracy of the fixture, the measuring tool and the tool itself, control the force of the process system, the deformation caused by the heat, the tool wear, the deformation caused by the internal stress and the measurement error, . In order to improve the machining accuracy, the original errors that generate the machining errors need to be analyzed. Different measures are taken to deal with the primary errors that cause the machining errors according to different situations. For the precision machining of parts should be used as much as possible to improve the precision of the use of precision machine tools, machining and control of thermal deformation; processing of parts with a forming surface, the main tool is to reduce the forming tool shape error and tool installation error. This method is widely used in production of a basic method. It seeks to eliminate or reduce these factors after identifying the main factors that cause machining errors. For example, slender shaft turning, now using a large reverse knife turning method, the basic elimination of axial cutting force caused by bending deformation. If supplemented by the spring tip, you can further eliminate the thermal deformation caused by the impact of thermal elongation.
2.the compensation of the original error, error compensation method is artificially created a new error to offset the original process system in the original error. When the original error is negative, the human error takes a positive value, otherwise, take a negative value, and try to make the two equal in size; or use one of the original errors to offset the other original error, and try to make the two equal in size , The opposite direction, so as to reduce the machining error and improve the machining accuracy.
3.the transfer of the original error, error transfer method is essentially the transfer of geometric error system, stress deformation and thermal deformation. There are many examples of error transfer methods. Such as when the machine can not meet the machining accuracy of parts processing requirements, often do not blindly improve the accuracy of the machine, but from the process or fixture to find ways to create the conditions for the machine to transfer the geometric error to the processing accuracy does not affect the go. Such as grinding spindle conical shaft and ensure its coaxiality, not by the rotary axis of the machine to ensure accuracy, but by the fixture to ensure. When the machine tool spindle and the workpiece with a floating link between the original machine tool spindle error was removed.
4.equally divided the original error. In the process, due to the rough or on the process of the existence of errors, often resulting in processing errors in this process, or due to changes in the performance of the workpiece material, or process on the process changes (such as rough refining, the original cutting process canceled ), Causing the original error occurred greater changes. To solve this problem, it is best to use grouping to adjust the method of dividing the error. The essence of this approach is to divide the original error into n groups according to their size, and reduce the error range of each blank to 1 / n, then adjust the processing according to each group separately.
5.Homogenization of the original error. With the shaft and the hole with high precision requirements, often using grinding process. The grinding tool itself does not require high precision, but it can perform micro-cutting on the workpiece during the relative movement with the workpiece. The high point is gradually worn off (of course, the mold is also worn away by the workpiece) and finally the workpiece reaches a very high level High precision. The friction and wear between the surface of the process, is the process of decreasing the error, which is the error-averaging method. Its essence is to use the closely related surfaces to compare with each other, check with each other to find the differences from the contrast, and then modify each other or each other based on the processing, the workpiece surface is continuously reduced and the average error of the homogenization. In production, many precision reference parts (such as flat, ruler, etc.) are processed by error-averaging
6.the local processing method. In the processing and assembly, some of the accuracy issues involved in the relationship between parts or components, quite complex, if blindly improve the accuracy of the parts themselves, and sometimes not only difficult or impossible, if used To the processing method (also known as self-processing repair method), it may be very convenient to solve the problem seems to be very difficult accuracy. Local processing method is commonly used in the machining of mechanical parts as an effective measure to ensure the machining accuracy of the parts.