Gear motors must withstand two types of torque: constant load torque and cutting torque (including frictional torque); acceleration/deceleration torque. The calculation methods for these two types of torque and the conditions that should be met when selecting a motor are described below.
Condition 1
When the machine tool is running without load, the torque applied to the motor should be less than 50% of the motor's continuous rated torque. Otherwise, the motor may overheat during cutting or acceleration/deceleration.
Condition 2
Acceleration (deceleration) time must be short and within the allowable range of the motor. Typically, load torque aids in the deceleration of the Vimart motor; therefore, if acceleration can be completed within the allowable time, deceleration can also be completed within the same timeframe. Thus, we only need to calculate the acceleration torque and, within the allowable time, determine whether this torque falls within the discontinuous region of the motor's mechanical characteristics.
Condition 3
Frequent positioning and acceleration/deceleration will cause the motor to heat up. At this time, it is necessary to calculate the root mean square value of the torque that the motor bears, Trms, and make it less than the rated torque Tc of the motor.
Condition 4
When the load fluctuates frequently, the root mean square value Tmrs of the load torque for one working cycle should be calculated and made to be less than the rated torque of the motor.
Condition 5
The time the motor operates at maximum cutting torque should be within the allowable range for the calculation of Ton.
Condition 6
The load inertia should be less than 3 times the motor's own inertia ( 2.5 times is recommended).
