Zero-transmission linear motor: structure, principle, characteristics and application

In recent years, with the continuous development of my country's manufacturing industry, its processing quality and production positioning accuracy have also been improved accordingly, which has led to the status of linear motors in its production industry applications. By converting electrical energy into the principle of linear motion machinery, the "zero transmission" key control technology of linear motors is realized. At the same time, the quality of production products and work efficiency are greatly improved. In order to adapt to the market competition in the new era, modern linear motor control technology has been widely used in major production fields in my country and has won unanimous praise from the industry.

Since entering the new era, my country has also invested a lot of energy and material resources in various industrial technologies, adopted advanced science and technology, and used linear motors to directly convert electrical energy, breaking the traditional intermediate transmission mechanism. At the same time, it also effectively reduced the probability of damage to the power system, guided the development direction of modern linear motors, realized the information management of key control technologies, and further enhanced the importance of linear motors in various production fields.

The structure of a linear motor

The structure of a linear motor can be seen as a rotating motor cut radially and the circumference of the motor expanded into a straight line. The stator is equivalent to the primary of the linear motor, and the rotor is equivalent to the secondary of the linear motor. When the primary is connected to the current, a traveling magnetic field is generated in the air gap between the primary and the secondary. The driving force is generated under the action of the traveling magnetic field and the secondary permanent magnet, thereby realizing the linear motion of the moving parts.

Working Principle of Linear Motor

Imagine that a rotary induction motor is cut open along the radial direction and flattened, which becomes a linear induction motor. The primary is made very long and extends to the position required for movement, and the secondary can also be made very long; the primary can be fixed and the secondary can move, or the secondary can be fixed and the primary can move. The magnetic flux generated in the stator after the alternating current is passed, and according to Lenz's law, eddy currents are induced on the metal plate of the moving body. Assuming that the induced voltage causing the eddy current is E, and there is inductance L and resistance R on the metal plate, the eddy current and magnetic flux density will generate a continuous thrust F according to Fermi's law.

In addition, linear motors are complex in types and have diverse structural methods. They can be divided into flat, cylindrical, and arc-shaped structures. The most widely used are flat motors, which can be divided into single-sided and double-sided structures. They can effectively enhance the normal force of the motor and increase the speed of the motor. However, they also have a certain impact on the structure and installation of the motor.

Characteristics of Linear Motors

1. High-speed response. Since some mechanical transmission parts with large response time constants, such as lead screws, are directly 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 fast.

2. High positioning accuracy. The linear drive system eliminates the transmission error caused by mechanical mechanisms such as the lead screw and reduces the tracking error caused by the lag of the transmission system during interpolation. The positioning accuracy of the machine tool can be greatly improved through linear position detection feedback control.

3. The elastic deformation, friction, wear and reverse clearance of the transmission link cause the motion hysteresis, while improving its transmission stiffness.

4. Fast speed and short acceleration and deceleration process.

5. The stroke length is unlimited. By connecting a linear motor in series on the guide rail, the stroke length can be extended indefinitely.

6. Quiet movement and low noise. Since the mechanical friction of the transmission screw and other components is eliminated, and the guide rail can be a rolling guide rail or a magnetic pad suspension guide rail (without mechanical contact), the noise during movement will be greatly reduced.

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

Applications of Linear Motors

Linear motors are mainly used in three areas:

1. Applied to automatic control systems, which are widely used;

2. As a driving motor for long-term continuous operation;

3. Applied in devices that need to provide huge linear motion energy in a short time and short distance.

U-slot brushless linear motor can be driven directly without converting rotation into linear motion, and the mechanical structure is simple and reliable. The motor runs super smoothly, has no cogging effect, has extremely fast dynamic response speed, small inertia, acceleration up to 20G, speed up to 10-30m/s, smooth movement at low speed 1µm/s, high rigidity, compact structure, and can be equipped with a linear encoder for high-precision position control. Its position accuracy depends on the selected encoder.

The stator track can be connected as needed, so theoretically the motor length is unlimited. The motor mover and stator do not move in contact, and there are no wear, jamming, or backlash problems associated with ordinary screws, balls, and belts. Therefore, our linear motors can achieve long-term maintenance-free operation.

This type of linear motor is particularly suitable for applications that require high speed and accuracy of the motion system, such as robots, actuators, linear stages, optical fiber arrangement and positioning, precision machine tools, semiconductor manufacturing, vision systems, electronic component insertion, factory automation, etc.