The motor is a very important power component on the 3D printer, its accuracy is related to the good or bad 3D printing effect, generally 3D printing on the use of stepper motor.
So are there any 3D printers that use servo motors? It's really awesome and accurate, but why not use it on regular 3D printers?
One drawback: it's too expensive! Compared to ordinary 3D printers is not worth it. If it is better for industrial printers is more or less the same, can improve the accuracy a little.
Here we will take these two motors, a detailed comparative analysis to see what the difference.
Different definitions.
Stepper motor is a discrete motion device, it is different from the ordinary AC and DC motors, ordinary motors to electricity to turn, but stepper motor is not, stepper motor is to receive a command to perform a step.
Servo motor is the engine that controls the operation of mechanical components in the servo system, which can make the control speed, position accuracy very accurate, and can convert the voltage signal into torque and speed to drive the control object.
Although the two are similar in the control mode (pulse string and directional signal), there are major differences in the use of performance and application occasions. Now a comparison of the use of the two performance.
Control accuracy is different.
Two-phase hybrid stepper motor step angle is generally , 1.8 °, 0.9 °
The control accuracy of an AC servo motor is guaranteed by the rotary encoder at the rear of the motor shaft. For a Panasonic fully digital AC servo motor, for example, for a motor with a standard 2500-line encoder, the pulse equivalent is 360°/10000=0.036° due to the quadruple frequency technology used inside the drive.
For a motor with a 17-bit encoder, the drive receives 217=131072 pulses per motor revolution, which means that its pulse equivalent is 360°/131072=9.89 seconds, which is 1/655 of the pulse equivalent of a stepper motor with a step angle of 1.8°.
Different low-frequency characteristics.
Stepper motor at low speed will appear low-frequency vibration phenomenon. The vibration frequency is related to the load condition and the performance of the drive, and is generally considered to be half of the no-load starting frequency of the motor.
This low-frequency vibration phenomenon determined by the working principle of the stepper motor is very detrimental to the normal operation of the machine. When stepper motors work at low speeds, damping technology should generally be used to overcome the low frequency vibration phenomenon, such as adding dampers to the motor, or using subdivision technology on the drive.
The AC servo motor runs very smoothly and does not vibrate even at low speeds. AC servo system has resonance suppression function, which can cover the lack of rigidity of the machinery, and the system has internal frequency resolution function, which can detect the resonance point of the machinery and facilitate system adjustment.
Different operational performance.
Stepper motor control is open-loop control, too high a starting frequency or too large a load is prone to the phenomenon of lost steps or blocking, too high a speed when stopping is prone to overshoot, so to ensure its control accuracy, should deal with the problem of speed up and down.
AC servo drive system for closed-loop control, the driver can directly sample the motor encoder feedback signal, the internal composition of the position loop and speed loop, generally will not appear stepper motor loss of step or overshoot phenomenon, the control performance is more reliable.
In summary, the AC servo system in many aspects of performance is better than the stepper motor. But in some less demanding occasions also often use stepper motor to do the execution motor. The 3D printer is a less demanding occasion, and the servo motor is so expensive, so the general choice of stepper motor.
Post time: Feb-05-2023