How to test the performance of a five-axis linkage machining center?
More and more factories in China have begun to introduce five-axis linkage CNC machine tools. How to evaluate whether the overall performance of a five-axis machine tool is qualified? Professionals all know that the accuracy acceptance of imported machine tools is generally based on the NAS979 standard.
In the process of purchasing imported machine tools, the machine tools have been qualified according to the NAS979 standard. However, accuracy problems in processing some complex parts were encountered, which posed serious challenges to the subsequent acceptance of imported machine tools. In order to verify the processing accuracy of machine tools, new testing standards must be established. Later, Chengdu Aircraft Company developed the S-type specimen.
On March 10, 2020, the official website of the Ministry of Science and Technology of China announced that the international standard ISO10791-7:2020 “Inspection Conditions for Machining Centers, Part 7: Precision Inspection of Finished Specimens ”, revised under the leadership of China, has been revised under the leadership of China. has been approved by the International Organization for Standardization (International Organization for Standardization). The ISO approval has been officially released, marking that China’s five-axis machine tool testing method “S specimen” has officially become an international standard.
What is this “S-shaped specimen”?
The “S test part” seems simple, just an S-shaped curve, but in fact this curve very cleverly integrates several processing characteristics of aerospace parts, and all the processing characteristics are integrated on this S-shaped part. S. At present, this prototype has mainly been used by domestic machine tool manufacturers to test the processing performance of five-axis machine tools. In particular, well-known foreign machine tool manufacturers were repeatedly taken aback by this prototype.
Dimensional drawing of an S-shaped specimen
It is worth mentioning that as long as the five-axis machine tool can process qualified “S specimens”, the five-axis machine tool can be safely used to process aerospace parts, especially thin-walled parts and complex shapes. “S test piece” is mainly used to test the dynamic machining accuracy of five-axis machine tools. It can test a series of problems such as geometric accuracy, positioning accuracy, comprehensive processing efficiency, comprehensive surface processing quality, vibration and vibration. of the complete machine, and also it can discover and research the causes of defects that affect the machining precision of machine tools, and solve repair problems after the precision of machine tools is lost or reduced.
“Specimen S” is a spline curve generated by control points, which can reflect the precision difference of the CNC system for complex surface curves. The feed direction changes several times during the machining process.
What are the difficulties in processing S-shaped samples?
The S-shaped specimen looks simple, just an S-shaped curve, but in fact this curve very cleverly integrates several processing characteristics of aerospace parts, and all the processing characteristics are integrated into this S-shaped part.
Processing difficulties:
The “S” specimen has thin walls, frequent reversals, high smoothness requirements, and high contour size requirements that match the transmission stiffness of the rotary axis and linear axis .
Five-axis machining center machine tools will use S-shaped specimens for performance testing
The main body of the S-shaped sample is an equal-thickness edge strip formed by a twisted curved surface with an S-shaped trend, and the shape of the surface is complex. When using bar cutters for machining, the tool axis must be changed continuously, and the machine tool must be able to perfectly execute the continuous change of coordinates of the five-axis linkage. During the machining process, the machine tool continuously inverts the coordinates of the five-axis linkage, which can reflect the geometric accuracy, positioning accuracy, dynamic characteristics, reversal error and other characteristics of the machine tool.
The importance of China’s “S test tube” becoming a standard
China’s five-axis machine tool inspection method “S specimen” has become an international standard, which has strengthened the international standard voice of China’s machine tool industry and its international influence in this technical field, breaking the monopoly of its foreign counterparts on the manufacture of high-end machine tools. enterprises and in the Chinese machine tool industry. This is of great importance in the journey of international standardization.
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