Views: 0 Author: Site Editor Publish Time: 2021-12-10 Origin: Site
Definition of CNC machining parts precision accuracy: Generally speaking, CNC machining parts precision accuracy refers to the ability of the machine tool to locate the tool tip point to the program target point. However, there are many ways to measure this positioning ability, and more importantly, different countries have different regulations. For example, according to the JIS standard, the data is significantly smaller than the NMTBA standard in the United States or the VDI standard in Germany. The same indicator name represents different meanings in different accuracy standards, but different indicator names have the same meaning. The above several standards, except for the JIS standard, are all calculated through mathematical statistics after multiple rounds of measurement on multiple target points on the CNC axis of the machine tool. They are mainly distinguished by the number of target points.
Here is the content list:
l The main reason for the accuracy of CNC machining parts precision.
l How to improve the accuracy of CNC machining parts precision?
l Special methods to improve the accuracy of CNC machining parts precision.
1. Spindle rotation error. The error of the spindle rotation refers to the change of the actual rotation axis of the spindle relative to its average rotation axis at each moment.
2. Guide rail error. The guide rail is used to determine the relative positional relationship of various machine tool components on the machine tool, and it is also the benchmark for the machine tool to move.
3. Transmission chain error. The transmission error of the transmission chain refers to the error caused by the relative movement between the transmission elements at the beginning and the end of the transmission chain. The transmission error is caused by the manufacturing and assembly errors of each component of the transmission chain and the wear during use.
1. Reduce the original error. Improving the geometric accuracy of the machine tool used for parts processing, improving the accuracy of fixtures, measuring tools and tools, and controlling the force, thermal deformation, tool wear, deformation caused by internal stress, and measurement errors of the processing system are all directly reducing the original error. To improve the accuracy of CNC machining parts precision, it is necessary to analyze the original errors that produce machining errors, and take different measures to solve the main original errors that cause machining errors according to different situations. For the processing of these parts, the geometric accuracy, rigidity and thermal deformation of the machine tool used should be improved as much as possible. For the processing of forming surface parts, it is to consider how to reduce the shape error of the forming tool and the installation error of the tool. This method is a basic method widely used in production. After finding out the main factors that produce machining errors, try to eliminate or reduce these factors.
2. Compensate the original error. The error compensation method is to artificially create a new error to offset the original error in the original process system. When the original error is a negative value, the man-made error is taken as a positive value, otherwise, take a negative value and try to make the two equal; or use one original error to offset the other original error, and try to make the two equal, The direction is opposite, to reduce the machining error and improve the accuracy of CNC machining parts precision.
3. Transfer the original error. The error transfer method is essential to transfer the geometric error, force deformation, and thermal deformation of the processing system. There are many examples of error transfer methods. For example, when the accuracy of CNC machining parts precision cannot meet the requirements of parts processing, it is often not the accuracy of the machine tools that blindly improve the accuracy of CNC machining parts precision, but to find ways to create conditions from the technology or fixtures to transfer the geometric errors of the machine tools to It does not affect the accuracy of CNC machining parts precision. For example, grinding the spindle taper hole to ensure its coaxially with the journal is not guaranteed by the rotation accuracy of the machine tool spindle, but by the fixture. When the machine tool spindle and the workpiece are connected by a floating connection, the original error of the machine tool spindle is transferred.
In processing and assembly, some CNC machining parts' precision accuracy problems involve the interrelationship between parts or components, which is quite complicated. If you blindly improve the accuracy of the parts and components themselves, sometimes it is not only difficult, or even impossible, if the in-situ machining method is adopted. , It is possible to easily solve the seemingly difficult accuracy problem. The in-situ machining method is commonly used in the machining of mechanical parts as an effective measure to ensure the machining accuracy of the parts.
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