The basic structure and working principle of linear stepper motor

The linear stepping motor can move linearly or reciprocate linearly. As the power source, the rotating motor needs to be transformed into linear motion with the help of gears, cam wheels and belts or steel wires. First introduced the structure of the linear stepper motor, secondly introduced the basic principle and working principle of the linear stepper motor, and finally explained its advantages and applications.

Introduction of linear stepper motor:

Linear stepping motor, or linear stepping motor, is generated by the magnetic rotor core interacting with the pulse electromagnetic field generated by the stator to generate rotation. The linear stepping motor converts the rotary motion into linear motion inside the motor.

The structure of linear stepping motor:

Compared with the rotary type, the linear stepping motor can directly move in a straight line, which can make the machine miniaturized.

Basic principle of linear stepper motor:

A screw and nut are used to engage, and some method is adopted to prevent the relative rotation of the screw and nut, so that the screw can move axially. Generally speaking, there are currently two ways to achieve this conversion. The first is to build a rotor with internal threads in the motor, and the internal threads of the rotor mesh with the screw to achieve linear motion. The second is to use the screw as The motor is out of the shaft, and an external drive nut engages the screw outside the motor to achieve linear motion. The result of this is to greatly simplify the design, making it possible to directly use the linear stepping motor for precise linear motion without installing an external mechanical linkage in many application fields.

Advantages of linear stepper motors:

(1) High-speed response

Generally speaking, the dynamic response time of mechanical transmission parts is several orders of magnitude greater than that of electrical components. Because some mechanical transmission parts such as lead screws with large response time constant are eliminated in the system, the dynamic response performance of the entire closed-loop control system is greatly improved, and the response is extremely sensitive and quick.

(2) High precision

Because the mechanical transmission mechanism such as the lead screw is eliminated, the tracking error caused by the lag of the transmission system during interpolation is reduced. Through linear position detection feedback control, the positioning accuracy of the machine tool can be greatly improved.

(3) High transmission rigidity and stable thrust

"Direct drive" improves its transmission rigidity. At the same time, the layout of the linear motor can be arranged according to the shape and surface structure of the machine tool guide rail and the force when the worktable moves. It is usually designed to be evenly distributed and symmetrical, so that its thrust is stable.

(4) Fast speed, short acceleration and deceleration process

Linear motors were first mainly used in maglev trains (speeds up to 500km/h), and are now used in machine tool feed drives to meet the maximum feed speed of ultra-high-speed cutting (required to reach 60-100m/min or higher) of course There is no problem. Also due to the high-speed responsiveness of "zero transmission", the acceleration and deceleration process is greatly shortened, so as to achieve high-speed instantaneously when starting, and it can stop immediately when running at high speed. The acceleration can generally reach 2～10g (g=9.8m/s2).

(5) The stroke length is not limited

Through the fixed part of the linear stepping motor in series on the guide rail, the stroke length of the moving part can be extended indefinitely.

(6) Low noise during operation

Because the mechanical friction of the transmission screw and other components is eliminated, and the guide rail pair can adopt a rolling guide rail or a magnetic pad suspension guide (no mechanical contact), the movement noise is greatly reduced.

(7) High efficiency

Since there is no intermediate transmission link, the energy loss during mechanical friction is eliminated.

Application field of linear stepper motor:

Linear stepping motors are widely used in many high-precision fields including manufacturing, precision calibration, precision fluid measurement, and precise position movement.