1. Trouble phenomenon:

The cumulative repeated positioning error of the worktable has reached 0.003 after 20 times, indicating that it is not only the error of the stepping motor, but the ball screw lead is 4mm harmonic The reduction ratio of the reducer is 1:80, and the step angle is 0.9°. The repeated positioning error of the stepper motor has exceeded 3 times of the machine tool accuracy inspection specification. Calculated according to the pulse equivalent of 0.125μm. The error of the mechanical system is more obvious.

　　 2. Inspection method:

1. Check the feed mechanism and compensation mechanism of the machine tool
The nominal diameter of the ball screw is too small (Φ20 accuracy grade 3 is too low, and The hand feel creeping phenomenon is more serious; the feed quick jump cylinder and ball screw have been designed to be positioned, and the assembly position deviation cannot be eliminated; the harmonic reducer and ball screw only have screw locking without key connection or pin link; ball screw bearing is not used And so on. It is found that the inverter, transformer and stepper motor controller are placed close to each other.

2. Check the electrical system of the machine tool

　　The data cable output from the PLC is not shielded, The mixed installation of strong current and weak current cables with the disk, etc. These problems are factors that affect the instability of the stepper motor system. The pulse equivalent is 0.125μm.

　　 3. Conclusion:

　　The unreasonable electrical design layout will directly cause accidental feeding system and compensation system errors. Due to the poor anti-interference ability of the stepper motor system in our country. In addition to the systematic errors of the mechanical system, the machine tool will be in an unstable state. Working status. The thorough method is to use the international advanced servo motor control system. The bearing grinder with the servo motor control system, of course. The quick-jump oil cylinder and the harmonic reducer are removed, and the ball screw and the servo motor are directly connected to the structure. , So that the mechanical system error is reduced. Although most of the bearing grinders adopting servo motor control system in our country are still pulse controlled, the comprehensive driving ability, anti-interference ability and repeat positioning accuracy of the servo motor are better than those of stepping motor bearing grinders. A big step. Due to the characteristics of the stepper motor system and many bugs, it is only a transitional product from the progress of mechanical hydraulic control to servo system control. Nowadays, there are few precision grinders controlled by stepper motor systems in foreign countries. The country is CNC machine tools. The country where the stepping motor system has been used for the longest time. With the acceleration of the technological transformation of the bearing industry in China, and the development of more and more high-quality bearing enterprises, the bearing grinder controlled by the stepping motor will eventually be servo Replaced by motors!