Fault inspection method for stepping motor control system of bearing grinding machine
The stepping motor of the bearing grinding machine and its control system are widely used, but the stepping motor system of two or more axes often has faults such as two systems being out of sync and the dimensional dispersion is unstable.
First, the failure phenomenon:
The cumulative repeat positioning error of the workbench has reached 0.003 in 20 times, indicating that it is not only the error of the stepper motor, the reduction ratio of the ball screw lead 4mm harmonic reducer is 1:80, the step angle is 0.9°, the stepping motor The repeated positioning error has exceeded the machine accuracy test specification by three times. Calculated according to the pulse equivalent of 0.125 μm. The error of the mechanical system is more obvious.
Second, the inspection method:
1. Check the feed mechanism and compensation mechanism of the machine tool
The nominal diameter of the ball screw is small (Φ20 accuracy level 3 is low, and the hand crawling phenomenon is more serious; the feed fast jumping cylinder and the ball screw are designed to be positioned, the assembly position deviation cannot be eliminated; the harmonic reducer and the ball screw Only the screw lock has no key connection or pin link; no ball screw bearings are used, etc. The inverter, transformer and stepper motor controller are found to be placed close together.
2. Check the electrical system of the machine tool
The data cable that is output from the PLC is not shielded, and the power of the distribution disk is mixed with the weak electric cable. These problems are all factors that affect the instability of the stepper motor system. Pulse equivalent is 0.125μm
Third, the conclusion:
The irrationality of these electrical design layouts will directly lead to accidental feed system and compensation system errors, due to the poor anti-interference ability of China's stepper motor systems. Coupled with systematic errors in the mechanical system, the machine will be in an unstable state of operation. The thorough method is to adopt the internationally advanced servo motor control system. Bearing grinding machines using servo motor control systems, of course. The fast-moving cylinder and the harmonic reducer are removed, and the ball screw and the servo motor are directly connected to each other, so that the mechanical system error is reduced. Although the bearing grinding machine adopting servo motor control system in China is mostly pulse control, the comprehensive drive capability, anti-interference ability and repeat positioning accuracy of the servo motor are a big step forward compared with the stepper motor bearing grinding machine. Due to the characteristics of the stepper motor system and many bugs, it is only a transitional product between the mechanical hydraulic control and the control of the servo system. The precision grinding machine controlled by the stepper motor system is rarely seen in foreign countries. The country with the longest motor system time. With the acceleration of the technical transformation speed of China's bearing industry, with the development of more and more high-quality bearing enterprises, the stepper motor controlled bearing grinding machine will eventually be replaced by servo motor！
