How to use linear stepper motors more reasonably?

1. Basic introduction to linear stepper motors

Linear stepper motors are devices that convert electrical pulse signals into linear motion. They convert rotary motion into linear motion through internal mechanical structures. Linear stepper motors usually consist of a rotary motor and a transmission device (such as a screw and a nut). This design enables linear stepper motors to directly perform linear motion, simplifying mechanical design and improving motion accuracy.

2. Basic working principle of linear stepper motors

1. Electromagnetic interaction: There is a stator and multiple magnetic poles inside the linear stepper motor. The stator generates multiple magnetic poles through a pulsed electromagnetic field. These magnetic poles interact with the permanent magnets in the rotor to drive the rotor to move linearly.

2. Current switching: By switching the current in sequence, the coil current is used to excite the two magnetic poles to produce opposite polarities. When the magnetic flux generated by the winding is the same as the magnetic flux of the permanent magnet, the magnetic flux of the subtracted magnetic pole is zero. At this time, the magnetic flux of the permanent magnet passes through the exciting magnetic pole in the same direction, pushing the rotor to move 1/4 of the stator pitch to the right each time.

‌3. Mechanical conversion: Linear stepper motors usually use the meshing mechanism of screws and nuts to achieve the conversion from rotational motion to linear motion. One way is to build a rotor with internal threads into the motor, and realize linear motion by meshing the internal threads and the screw; another way is to use an external drive nut and the screw outside the motor to mesh to achieve linear motion.

‌4. Control method: By issuing instructions through the control circuit, changing the order, frequency and number of electric pulses, the direction, speed and angle of the stepper motor can be accurately controlled. This control method enables the stepper motor to realize a simple and low-cost open-loop control system without a closed-loop feedback system.

3. Main structural advantages of linear stepper motors

1. High-speed responsiveness: Linear stepper motors eliminate traditional mechanical transmission parts such as lead screws, which greatly shortens the dynamic response time of the entire system and makes the response sensitive and fast.

2. High precision: Due to the removal of mechanical transmission mechanisms such as lead screws, the hysteresis error of the transmission system is reduced. Through linear position detection feedback control, the positioning accuracy of the machine tool can be significantly improved.

3. High transmission stiffness and stable thrust: The linear stepper motor adopts a "direct drive" design to improve the transmission stiffness. Its layout can be arranged according to the surface structure of the machine tool guide rail and the force conditions during the movement of the worktable. It is usually designed to be evenly distributed and symmetrical to make its movement thrust stable.

4. Fast speed and short acceleration and deceleration process: Due to the elimination of the intermediate transmission mechanism, the acceleration and deceleration time of the linear stepper motor is significantly shortened, and fast start-up and forward and reverse operation can be achieved.

5. Unlimited stroke length: By connecting the fixed parts of multiple linear stepper motors in series, the stroke length of the moving part can be infinitely extended, which is suitable for application scenarios requiring long strokes.

‌6. Low noise during operation: Since the mechanical friction of components such as the transmission screw is eliminated, the guide rail can use a rolling guide rail or a magnetic pad suspension guide rail (without mechanical contact), which greatly reduces the movement noise.

‌7. High efficiency: There is no intermediate transmission link, which reduces the energy loss during mechanical friction and improves the overall efficiency.

4. Precautions for using linear stepper motors

1. Correct installation: Before installing the linear stepper motor, it is necessary to select the appropriate motor specifications according to the installation environment and motion state, and determine the installation space and fixing method. After the installation is completed, it is necessary to check to ensure that it is stable and there is no oil or water leakage. At the same time, check whether the circuit connection is correct and whether the voltage and current meet the requirements.

‌2. Correct debugging: After starting up, the stepper motor needs to be debugged, including adjusting the motor speed, acceleration and deceleration, and motor position. Check the running status of the motor to ensure normal operation without jitter or instability. At the same time, check the status of the transmission device to ensure that the bearing is normal and not damaged or loose.

‌3. Proper maintenance‌: Regularly check the running status of the motor, find and repair faults in time; Regularly check the transmission device and replace damaged parts in time; Regularly check the control system to ensure stable operation of the system; Regularly check the circuit of the motor to ensure that it is normal and not damaged.

‌4. Avoid the influence of vibration, temperature change, heat source and magnetic field: The installation of the linear stepper motor should try to avoid these factors to ensure that the motor runs in a good environment.

‌5. Check the power supply voltage and the operating current of the controller: Regularly check the power supply voltage and the operating current of the controller to prevent circuit overload.

‌6. Protect the screw and lead wire: During the process of taking and installing the motor, avoid directly lifting, pulling, and holding the screw with your hands to prevent the motor from falling and colliding. Protect the screw from radial force and avoid applying lubricating grease not provided by the factory. Pay attention to the protection of the lead wire and avoid pulling the lead wire with force.

‌7. Control the load and operating environment‌: In actual use, the load should be less than 50% of the maximum thrust of the motor performance at the set speed to avoid impact load, emergency stop and emergency start. The ambient temperature of the motor should be between -20℃ and 55℃.

Source:https://chestnut-watermelon-lx77f7.mystrikingly.com/blog/how-to-use-linear-stepper-motors-more-reasonably