A lead screw stepper motor is a motor that converts the rotational motion of a motor into linear motion. It is mainly composed of motor, reducer and screw rod. The motor is usually an AC motor or a DC motor, the reducer usually adopts a planetary gear reducer, a bevel gear reducer or a worm gear reducer, and the screw usually adopts a thread pair structure.
The working principle of the lead screw stepper motor is based on the conversion of the rotational motion of the motor into the linear motion of the screw. The motor converts the high-speed low-torque rotary motion into low-speed high-torque rotary motion through the reducer, and then converts the rotary motion into linear motion through the thread pair of the screw.
Designed for precise linear motion, this linear positioning drive consists of a stepper motor with a built-in lead screw, replacing a normal output shaft. The compact size of the motor makes it possible to move objects or platforms with ease and high precision. These motors are commonly used in DIY 3D printers (such as RepRap) and CNC machines. An integrated stainless steel threaded rod extends from the face of the stepper motor, eliminating the need for bulky couplings or set screws.
Lead screw stepper motors can achieve high-precision linear positioning and transmission, usually with small errors and high repeat positioning accuracy.
The lead screw stepper motor converts high-speed and low-torque rotary motion into low-speed high-torque rotary motion through a reducer, thereby improving energy utilization efficiency.
Lead screw stepper motors typically employ closed-loop control and encoder feedback for precise position and speed control.
The lead screw stepper motor has simple structure, convenient assembly, easy maintenance and repair.
The rotor of the lead screw stepper motor uses a permanent magnet. When the stator winding is energized, a vector magnetic field is generated, which drives the rotor to rotate at a certain angle, so that the direction of a pair of magnetic fields of the rotor is consistent with the direction of the stator magnetic field. Every time an electrical pulse is input, the motor advances by a step angle. Therefore, the rotation of the stepper motor can be controlled by controlling the number of pulses, frequency and the sequence of energizing the windings of each phase of the motor.
Like other motors, the screw stepper motor also has an iron core and a winding coil inside. The resistance of the winding coil produces copper losses that are proportional to the square of the current. Harmonic losses also occur if the current is not the standard DC or sine wave. The iron core has a hysteresis eddy current effect, and loss will also occur in the alternating magnetic field, and its size is related to material, current, frequency and voltage, which is called iron loss. Because the screw stepper motor usually pursues higher positioning accuracy and torque output, the efficiency is relatively low, the current is large, and the harmonic component is also high. The frequency of the alternating current also changes with the change of the rotational speed. Therefore, screw stepper motors generally suffer from heating, and the situation is more serious than that of ordinary AC motors.
Lead screw stepper motors are widely used in industrial automation, machine tool processing, printing and packaging, medical equipment and other fields. In the field of machine tool processing, lead screw stepper motors can be used to realize automatic control of machine tools, high-precision positioning and guarantee of processing quality. In the field of medical equipment, lead screw stepper motors can be used to achieve high-precision control and position adjustment of medical equipment. In the field of printing and packaging, the lead screw stepper motor can be used to realize the positioning control of the printing machine and the transmission of the roll.
Lead screw stepper motors can be classified according to structure type, mainly including external drive type, through shaft type and fixed shaft type. Among them, the externally driven screw stepper motor does not include a driver, and its screw is generally made of stainless steel. Pay attention to the rated current of the motor when using it, and do not let the driver current exceed the rated current of the motor itself, otherwise it will easily lead to abnormal heating or even burning of the motor.
The through shaft type screw stepper motor also does not include a driver, and it is necessary to select a suitable end connection method to prevent the screw from rotating. Special attention should be paid to overtravel during use to prevent the screw from falling out.
The front end of the fixed shaft type screw stepper motor will protrude from the rod but will not rotate, you only need to choose a suitable driver for matching use.
Lead screw stepper motors can be divided into AC motor lead screw stepper motors and DC motor lead screw stepper motors according to the type of motor. AC motor lead screw stepper motors generally have higher speed and lower torque, while DC motor lead screw stepper motors have higher torque and lower speed.
Lead screw stepper motors can be divided into planetary gear lead screw stepper motors, bevel gear lead screw stepper motors and worm gear lead screw stepper motors according to the type of reducer. Different types of reducers have different characteristics. For example, planetary gear reducers have the characteristics of small size, high transmission ratio and low noise, while worm gear reducers have large transmission ratios and high transmission efficiency.
Lead screw stepper motors can be divided into small-diameter lead screw stepper motors and large-diameter lead screw stepper motors according to the diameter of the screw. Smaller diameter lead lead screw stepper motors are generally suitable for small loads and low speed applications, while larger diameter lead lead screw stepper motors are suitable for larger loads and high speed applications.
Lead screw stepper motors can be divided into unidirectional lead screw stepper motors and bidirectional lead screw stepper motors according to their working methods. Unidirectional lead screw stepper motors can only achieve linear motion in one direction, while bidirectional lead screw stepper motors can achieve linear motion in both positive and negative directions.