The hottest step motor controlled bearing grinder

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Stepping motor controlled bearing grinder

with the introduction of a large number of stepping motor controlled bearing grinders to the market, more and more problems of stepping motor system control have surfaced, and the problems of single axis controlled stepping motor system are less, but stepping motor systems with more than two axes often have faults such as two systems are not synchronized, dimensional dispersion is unstable and so on. There are many problems in the stepper motor system. We have done analysis and Research on the ball bearing inner ring groove grinder, and have tried several domestic brands of stepping motors, and found that the two systems are seriously out of sync. The asynchronous error test starts from PLC, position control module, stepping motor driver and stepping motor. The lead of ball screw is 4mm, the reduction ratio of harmonic reducer is 1:80, the step torque angle is 0.9, and the pulse equivalent is 0.125 M. The repeated positioning error of stepping motor has exceeded 3 times of the accuracy test standard of machine tool. Calculated according to the pulse equivalent of 0.125 m, the cumulative repeated positioning error of the workbench has reached 0.003 in 20 times. The data in Table 1 shows that not only the error of stepping motor, but also the error of mechanical system is more obvious. We analyzed the feed mechanism and compensation mechanism of this machine tool, and found that the mechanical problem is also serious. First, the nominal diameter of the ball screw is relatively small (20), the accuracy grade is 3, the sample size is small to the gold wire grade with a diameter of 0006mm is low, and the hand feeling crawling phenomenon is relatively serious; Second, the feed quick jump cylinder and ball screw are designed to be positioned, and the assembly position deviation cannot be eliminated; Third, the harmonic reducer and ball screw only have screw locking, and there is no key connection or pin connection; Fourth, ball screw bearings are not used. Then we analyzed the electrical system of the machine tool, and found that the frequency converter, transformer and stepping motor controller were placed close, the data cable output from PLC was not shielded, and the strong and weak current cables of the distribution panel were mixed, etc. These problems are the factors that affect the instability of the stepping motor system. At present, the anti-interference ability of stepping motor system in China is poor, but the production capacity of bio based chemicals produced by lignocellulose (such as rice husk and corn straw) increases most rapidly. The unreasonable design layout will directly produce accidental feeding system and compensation system error, plus the systematic error of mechanical system, the machine tool will be in an unstable working state. It is not to say that as long as the hydraulic feed compensation system of the machine tool is changed into the stepper motor feed compensation system, the overall comprehensive performance of the machine tool will be significantly improved. The stepper motor replaces the original complex hydraulic feed compensation system, eliminating the original hydraulic fluctuation and the error of the mechanical parts processing transmission chain, and the stepper motor can divide the feed process into several stages. In each stage, different pulse frequencies can be selected to control the feed speed, and the pulse number can be used to control the precision feed of the machine tool workbench, which is indeed a big step forward from the bearing grinder of the original hydraulic system. However, what follows is that other relevant parts of the machine tool should also be updated to meet the grinding technical requirements of the machine tool. Jinjitong suggests that the weak anti-interference ability of stepping motor system should not be ignored in the design of mechanical structure or electrical system. If our solutions to the above problems are not properly solved, if the overall parts of the machine tool, especially the key parts, are still the standard of the original mechanical hydraulic system machine tool, WWW, the bearing grinder controlled by the stepping motor system will not be improved in essence. Of course, the most thorough way is to adopt the most advanced servo motor control system in the world. The bearing grinder with servo motor control system removes the fast jump oil cylinder and the harmonic reducer that has maintained a double-digit growth trend in the market. The ball screw and servo motor direct connection structure are adopted to minimize the error of the mechanical system. Jinjitong pointed out that although most of the bearing grinders using servo motor control system in China are still pulse controlled, the comprehensive driving ability, anti-interference ability and repeated positioning accuracy of servo motor are a big step forward compared with stepping motor bearing grinders. Due to the characteristics of the stepping motor system and many bugs, it is only a transitional product from the mechanical hydraulic control to the servo system control. In addition to implementing the development strategy of high-efficiency and green plastic granulator, there are few precision grinding machines controlled by the stepping motor system now. China is the country that has applied the stepping motor system on CNC machine tools for the longest time. With the acceleration of technological transformation in China's bearing industry and the development of more and more enterprises processing high-quality bearings, the bearing grinder controlled by stepping motor will eventually be replaced by servo motor

source: Jinming international machinery and Mould Exhibition Company

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