The measurement method is to perform a return-to-origin from 7 arbitrary positions, determine the stop position, and use the larger difference to be read as the precision of the return-to-origin.
It should be pointed out that the existing detection of positioning accuracy is measured under the condition of fast and positioning. For some CNC machine tools with poor feed system demeanor, when positioning with different feed speeds, different positioning accuracy values will be obtained. In addition, the measurement result of positioning accuracy is related to the ambient temperature and the working state of the coordinate axis. At present, most CNC machine tools adopt a semi-closed loop system, and most of the position detection components are installed on the drive motor, which produces an error of 0.01~0.02mm within a 1m stroke. It is not surprising. This is an error caused by thermal elongation. Some machine tools use pre-tensioning (pre-tensioning) to reduce the impact.
The repeated positioning accuracy of each coordinate axis reflects the basic accuracy index of the axis. It reflects the stability of the axis motion accuracy. It is impossible to imagine that the machine tool with poor accuracy can be used in production stably. At present, as the CNC system has more and more functions, the system error of the movement accuracy of each ejector mark, such as the accumulated pitch error and the backlash error, can be systematically compensated. Only the random error cannot be compensated, and the repeated positioning accuracy It just reflects the comprehensive random error of the feed drive mechanism, which cannot be corrected by numerical control system compensation. When it is found to be out of tolerance, only the feed drive chain can be fine-tuned and corrected. Therefore, if the machine tool is allowed to be selected, it is better to choose a machine tool with high repeat positioning accuracy.
"Crash Problem" in the Process of CNC Machine Tool Processing
Aiming at the common causes of collisions in the machining process of CNC machine tools, the possible causes of collisions are analyzed and discussed from the perspective of the application of the numerical control system, and corresponding preventive measures are proposed. In order to reduce the occurrence of crashes and ensure the safe and reliable operation of machine tools.
With the continuous development and improvement of the equipment manufacturing industry, the market demand for high-speed, high-efficiency, and high-precision CNC machine tools is increasing. However, in actual applications, due to various reasons, there are still many problems in the processing process, which make the processing dimensions inaccurate, and even crashes and other problems that seriously affect the quality of the product, causing unnecessary economic losses. This article lists several common causes of CNC machine tool failures and analyzes them. Taking the specific numerical control system as an example, corresponding preventive measures are put forward.