Stepping motors are famous for their accurate positioning capability and high torque output at low speed, but they need to carefully determine the size to ensure that the motor matches the load and application parameters, to minimize the possibility of out-of-step or motor stall.
Adding a gearbox to a stepping motor system can improve motor performance by reducing the inertia ratio of the load to the motor, increasing the load torque and reducing motor oscillation.
One of the reasons for the lack of step distance in stepping motor applications is to reduce the inertia ratio between load and motor.
The ratio of load inertia to motor inertia determines how the motor can drive or control the load, especially in the acceleration and deceleration parts of the motion curve.
If the load inertia is significantly higher than the motor inertia, the motor will have difficulty controlling the load and overshoot (Overspeed steps out of command range)Or undershoot (Number of steps).
A high load inertia ratio may also cause the motor to consume too much current and stop.
One way to reduce the inertia ratio than JL = load inertia JM = Motor inertia is to use a motor with a larger inertia.
But this means higher costs, more weight and more on other parts of the system (Such as couplings, cables and driver assemblies)The trickle effect.
Instead, adding a gearbox to the system reduces the inertia ratio of the load to the motor by the square of the gear ratio.
I = gear reduction, increasing the torque of the load. Another reason for using a gearbox with a stepping motor is to increase the torque that can be used to drive the load. When the load is from the motor-
When the gearbox is driven in combination, the gearbox will multiply the torque of the motor by an amount proportional to the gear ratio and gearbox efficiency.
To = torque output on gearbox shaft Tm = torque output on motor shaft & eta;
= Gearbox efficiency, but although gearboxes increase torque, they decrease speed. (
This is why they are sometimes called'Gear Reducer'Or'Reducer'The reason. )
In other words, when the gearbox is connected to the motor, the rotation speed of the motor must be faster-Equal to gear ratio-Pass the target speed to the load.
No = speed output Nm on gearbox shaft = speed output on motor shaft, and stepping motor torque usually decreases rapidly with increasing speed due to braking torque and other losses.
This inverse relationship between speed and torque means that before the motor cannot transmit the required torque (Even multiplied by the gear ratio)It is only feasible to increase the speed by a certain amount.
Reduce resonance and vibration, but accelerating the motor is really good.
When the gearbox is installed, the extra speed required by the motor means that the motor operates outside its resonance frequency range, within which oscillation and vibration will cause the motor to step out or even stall.
In addition to ensuring that the gearbox has the correct torque, speed and inertia values, it is also important to select a high precision and low recoil gearbox-
Especially when connecting the gearbox to the stepping motor.
Recall that the stepper motor with a gearbox runs in an open-loop system, and the backlash in the gearbox reduces the positioning accuracy of the system without feedback to monitor or correct the positioning error.
This is why stepping applications often use high-precision planetary gearboxes with gaps as low as 2 to 3 arc points.
Some manufacturers provide stepping motors with harmonic gears that can achieve zero backlash under most application conditions.
TAG gear stepping motor