How to select a suitable stepping motor for a CNC engraving machine:
First, choose to maintain torque
Maintaining the torque is also called static torque, which refers to the moment when the stepping motor is energized but does not rotate, the stator locks the rotor. Since the torque of the stepping motor is close to maintaining the torque at low speed, and the torque of the stepping motor rapidly attenuates with the increase of speed, the output power also changes with the increase of speed. Therefore, maintaining the torque is one of the most important parameters for measuring the load capacity of the stepping motor. For example, a stepping motor that generally speaks of 1N.m without explanation can be understood as keeping the torque at 1N.m.
Select Phase Number
The two-phase stepper motor has low cost, the step angle is at least 1.8 degrees, the vibration is large at low speed, and the moment drops rapidly at high speed. It is suitable for high-speed conditions and does not require high accuracy and stability. The step angle of the three-phase stepper motor is at least 1.2 degrees, the vibration is smaller than that of the two-phase stepper motor, the low-speed performance is better than that of the two-phase stepper motor, and the maximum speed is 30 to 50 % higher than that of the two-phase stepper motor, which is suitable for high-speed and high accuracy. occasions with high requirements for accuracy and stability; The step angle of the 5-phase stepper motor is smaller, and the low-speed performance is better than that of the 3-phase stepper motor, but the cost is high. It is suitable for low-speed and medium-low speed sections and requires high accuracy and stability.
III. Select Stepping Motor
It is necessary to follow the principle of selecting the actuator after selecting the motor, first to clarify the load characteristics, and then to find the stepping motor that best matches the load characteristics by comparing the static moment and the moment frequency curve of the different types of stepping motor. When the precision requirement is high, a mechanical deceleration device should be used to make the motor work in the state with the highest efficiency and the lowest noise; Avoid making the motor work in the vibration area, if necessary, by changing the voltage, current or increasing the damping method; In terms of power supply voltage, it is recommended that 57 Motors adopt DC 24V-36V, 86 Motors adopt DC 46V, 110 Motors adopt higher than DC 80V; The large moment of inertia load should choose the motor with a larger seat number; When the inertia load is high and the working speed is high, the motor should use a gradual increase in frequency to prevent the motor from missing, reduce noise, and improve the positioning accuracy when stopping. In view of the fact that the torque of the stepping motor is generally below 40 Nm, which exceeds this torque range, and the operating speed is greater than 1000 RPM, servo motors should be considered for selection. Generally, AC servo motors can operate normally at 3000 RPM, and DC servo motor cocoa can operate normally at 10,000 RPM.
Select drive and score
It is better not to choose the whole step state, because the whole step state vibrates more; Select drive with low current, high inductance and low voltage. The use of actuators larger than the operating current, the use of subdivision actuators when low vibration or high precision are required, and the use of Gaodianya actuators for large torque motors to achieve good high-speed performance; In the case where the actual use speed of the motor is usually higher and the accuracy and stability requirements are not high, it is not necessary to choose a high fraction drive in order to save costs; Under the condition that the actual operating speed of the motor is usually very low, a large fine fraction should be selected to ensure smooth operation and reduce vibration and noise; In short, when selecting the fine fraction, the actual operating speed of the motor, the range of negative moment, the setting of the speed reducer, the accuracy requirements, the vibration and noise requirements should be considered comprehensively.