China's bearing grinding machine stepper motor and control system along with large quantities of stepper motor control to the market bearing grinding machine, stepper motor system control more and more problems surfaced, single-axis stepper motor control system problems also less, but more than two axes stepper motor systems, such as the two systems often are not synchronized, the size difference unstable bulk failure.
Stepper motor system problems are manifold. Our inner groove ball bearing grinding done analysis, has tried several brands of domestic stepper motor and found the two systems are not synchronized phenomenon is very serious. Sync error test from the PLC, the Position module, stepper motor drives and stepper motor starts.
Ball screw lead 4mm, harmonic gear reduction ratio is 1:80, step angle of 0.9 ° stepper motor positioning error has been repeated more than machine precision test three times. In accordance with the pulse equivalent to 0.125μm calculated cumulative repeated positioning error in table 20 has reached 0.003. The data in Table 1 illustrate only the error of the stepping motor, the mechanical error of the system is more apparent.
We analyzed this machine feed mechanism and the compensation mechanism, there is a mechanical problem more serious. First, the ball screw nominal diameter smaller (Φ20), accuracy class 3 low, and feel creeping phenomenon is more serious; Second, the feed cylinder and ball screw design fast jump over positioning and assembly position error can not be eliminated; Third, the harmonic gear and ball screw locking is not only a key link connecting or off; fourth, did not use ball bearings and so on.
Then we analyze the machine's electrical system and found that the inverter, transformer and stepper motor controller placed eccentric anomaly, the output data from the PLC is not shielded cable with disk mixed electric and electronic cables and so on . These issues are affecting the stepper motor system instability. , Pulse equivalent to 0.125μm.
Due to our current stepper motor system anti-jamming capability is poor, these electrical design layout will have chance unreasonable direct feed system and compensation system errors, coupled with systematic errors in the mechanical system, the machine will be in precarious work state.
Not to say that as long as the machine's hydraulic compensation system feeding into the stepper motor feed compensation system, overall performance of the entire machine will definitely improved significantly. Stepper motor to replace the original complex hydraulic feed compensation system, the original hydraulic fluctuations and mechanical parts processing errors eliminates transmission chain, and stepper motor feeding process can be divided into several phases, each can use different pulse frequency control feed rate, the number of pulses can be used to control the machine table to sophisticated, it is indeed more than the original hydraulic system bearing grinder progress a big step. However, the attendant is part of the machine have to follow other relevant update the design, will meet the technical requirements of the machine grinding. Whether mechanical structure design or the design of the electrical system should not be ignored stepper motor system features anti-interference ability is relatively weak. If we enjoy the above solution to the problem is not properly addressed, especially if the machine as a whole is a key component parts or the original standard machine hydraulic system, controlled by a stepping motor system bearing grinder would not get from essentially improvements.
Of course, the most thorough way is using the most advanced servo motor control system. Servo motor control system bearing grinder, will soon jump cylinders and harmonic reducer removed, using ball screws and servo motors are directly connected structure, which makes the mechanical system error is minimized. Although China's servo motor control system bearing grinder majority or impulse control, but integrated servo motor drive capability, anti-interference ability and repeat positioning accuracy, than the stepper motor bearing grinder and a big step forward. As the stepper motor system features and many BUG, it's just mechanical hydraulic control advances to the servo system control in the middle of a transitional product, abroad now rarely seen by a stepping motor system control precision grinding machines, the country is in CNC machine tools Applications Stepper motor system on the longest in the country. As China's bearing industry technical innovation accelerates, as more and more processing of high quality bearings enterprise development, bearing grinder stepper motor control servo motor will eventually be replaced.