Semi-auto Polystyrene Shape Molding Machine how to transform the drive more appropriate
At present, the domestic production of Semi-auto Polystyrene Shape Molding Machine drive for the two, stepper motor drive and AC servo drive, many customers believe that the use of servo motor can improve the Semi-auto Polystyrene Shape Molding Machine cutting accuracy, it must be configured AC servo, Tianfu NC engineers believe that this view is wrong, because the Semi-auto Polystyrene Shape Molding Machine itself is used for roughing a numerical control equipment, cutting the size of the accuracy is not equipped with what drive, the size of the precision is related to many factors. Today and we explain the stepper motor and drive motor What are the differences.
First, the control accuracy is different
The accuracy of the AC servo motor is guaranteed by the rotary encoder at the rear of the motor shaft. To Panasonic all-digital AC servo motor, for example, with a standard 2500-wire encoder for the motor, because the drive inside the use of quadruple frequency technology, the pulse equivalent of 360 ° / 10000 = 0.036 °. For motors with 17-bit encoders, the driver receives 217 = 131072 pulse motors for one turn, ie, the pulse equivalent is 360 ° / 131072 = 9.89 seconds. Is 1/655 of the pulse equivalent of the stepper motor with step angle of 1.8 °.
Second, the moment frequency characteristics are different
The output torque of the stepper motor decreases as the speed increases and decreases drastically at higher speeds, so the maximum operating speed is typically between 300 and 600 RPM. AC servo motor for constant torque output, that is, its rated speed (usually 2000RPM or 3000RPM), can output the rated torque, above the rated speed for the constant power output.
Third, the overload capacity is different
Stepper motors are generally not overloadable. Semi-auto Polystyrene Shape Molding Machine AC servo motor has a strong overload capacity. To Panasonic AC servo system, for example, it has a speed overload and torque overload capacity. The maximum torque is three times the rated torque and can be used to overcome the moment of inertia of the inertial load at the moment of activation. Stepping motor because there is no such overload capacity, in order to overcome this inertia moment in the selection, often need to select a larger torque of the motor, and the Semi-auto Polystyrene Shape Molding Machine normal work without the need for such a large torque, there is a moment The phenomenon of waste.
Fourth, low-frequency characteristics of different
Stepper motor at low speed prone to low frequency vibration phenomenon. The vibration frequency is related to the load condition and the drive performance. It is generally believed that the vibration frequency is half of the motor no-load take-off frequency. This low-frequency vibration phenomenon, which is determined by the working principle of the stepper motor, is very unfavorable to the normal operation of the machine. When the stepper motor is operating at low speed, damping technology should generally be used to overcome the low frequency vibration phenomenon, such as in the motor plus damper, or drive using sub-technology.
AC servo motor running very smoothly, even at low speed will not appear when the vibration phenomenon. AC servo system with resonance suppression function, can cover the mechanical rigidity, and the system has a frequency resolution function (FFT), can detect the mechanical resonance point, easy to adjust the system.
Fifth, the speed response performance is different
Stepping motor from the static acceleration to the working speed (usually hundreds of revolutions per minute) need 200 to 400 milliseconds. AC servo system acceleration performance is better, to Panasonic MSMA 400W AC servo motor, Semi-auto Polystyrene Shape Molding Machine for example, from the static acceleration to its rated speed 3000RPM only a few milliseconds, can be used for fast start and stop control occasions.
Six, running performance is different
Stepper motor control for the open-loop control, start the frequency is too high or the load is too large prone to stealing or stall phenomenon, stop the high speed is too prone to overshoot phenomenon, so to ensure its control accuracy, should be handled L, slow down the problem. AC servo drive system for the closed-loop control, the drive can be directly on the motor encoder feedback signal sampling, the internal configuration of the location ring and speed loop, generally do not appear stepping motor stepping or overshoot phenomenon, control performance is more reliable.
In summary, the AC servo system in many performance aspects are better than stepper motor. But for Semi-auto Polystyrene Shape Molding Machine for this roughing of the equipment, there is no need to match the servo motor. Of course, some users in order to pursue perfection, with a servo motor.