Linear motors do not have the function of a reducer. Therefore, it takes a lot of power to withstand the cutting reaction force or stop, which is its disadvantage. This has the advantage that the position detection can be carried out in the vicinity of the point of action (machining point) by means of a linear scale. Also, since the number of parts is small, the error between the parts is small when assembling the parts, and the positioning accuracy is excellent. It does not have the normal rotation of the motor and the screw drive, and is not affected by the centrifugal force, so the speed can be more than twice that of the screw drive. In the future, linear motors are the main application areas for fine machining and sub-micron precision machining without cutting thrust by ultra-high speed spindle machining.

A motor is a motor that produces a linear motion instead of a rotary motion. The propulsive force is generated directly on the moving part (sliding table), and an additional mechanism for converting the turning motion into a linear motion is no longer required. Therefore, its positioning and repeatability are high, and it has high speed and acceleration. The structurally less friction members ensure high reliability. Linear motors are maintenance-free and have low noise. However, the entire machine structure using a linear motor is not buffered, so the control system is complicated, and it is necessary to take protective measures to solve the problem that the magnet attracts chips and heat. The price is also more expensive than the ball screw.

The ball screw drive system has high rigidity in the running direction, high precision and low noise. It has higher feed force than linear motor, but the speed and acceleration are lower, and the maintenance requirements are also Relatively high.

There is still a misunderstanding in the understanding of the ball screw and the linear motor. It is considered that the original machine tool screw can be replaced by a linear motor. Although this can simplify the mechanical structure of the machine tool, it does not necessarily mean that the mechanical design is simple. Because the machine tool is not a complete rigid body in the case of high-speed operation, there will be some changes. The research on the dynamic performance of the machine tool is still lacking in China. There may be less research on this aspect from the design method and design method. This will cause some domestic phenomena. It is very desirable to test this high technology, and then go to the test. If the test is not good, it will give up. There is no in-depth study of why, or improvement from the method, this is the problem.

The same problem is encountered when using a linear motor abroad. For example, during the movement, the headstock is square, but in reality it is oscillated under high-speed operation, and the accuracy is affected. It may not be obvious when running at low speed, but it is reflected at high speed. Linear motor technology needs to be matched with the system when it is used on the machine tool. It is not only a part, but can be applied to the work of the automobile production line for 24 hours. Therefore, this dynamic problem is an urgent problem that the host manufacturer needs to solve in the future.

The use of linear motors in large-scale equipment still has certain advantages, because the secondary of the linear motor is mounted on the machine bed through a series of continuous splicing, and the required ratio can be calculated in advance, which can reduce the cost.

In the 1990s, linear motors entered the market as machine tool drives and were used in CNC machine tools. The biggest advantage of a linear motor is the high speed of 300m/min. At this point in speed, the linear motor exceeds the ball screw by nearly 3 times. Linear motors have unparalleled advantages in ultra-high-speed operating conditions.

However, the ball screw has its unique advantages over the linear motor: the price advantage - the price of the ball screw is much lower than that of the linear motor, and the production cost is also the same; the low energy consumption - the energy consumption of the linear motor is Many times the ball screw, it means a lot of uneconomical problems; high rigidity - the machine tool using the ball screw is more rigid than the machine using the linear motor; magnetic - the machine using the linear motor forms around the table A very strong magnetic field that absorbs iron filings and has a negative impact on the production process of CNC machine tools.

In addition to linear motors and ball screws, there are a range of linear actuators such as racks, hydraulic cylinders or pneumatic cylinders. In the past few decades, the ball screw has dominated the field due to its economy, low energy consumption and high rigidity, and its market share is increasing, and it will continue to play an important role in the future.

In high-speed and ultra-high-speed machining, high dynamic characteristics and control accuracy are required; instantaneous high speed and instantaneous stop in high-speed operation; low vibration, low noise, stable operation; high reliability and long service life. Among the various linear drive components, the precision high-speed ball screw pair and linear motor are the core functional components that can meet the above requirements in the fast servo feed system of large, precise and high-speed CNC equipment.

As an electromechanical system, the line motor has the characteristics of high speed response, high positioning accuracy, high dynamic stiffness, fast speed, short acceleration and deceleration process, unlimited stroke length, quiet motion, low noise and high efficiency. The mechanical structure is simplified, the electrical control is complicated, and it conforms to the development trend of modern electromechanical technology. However, linear motors also have many shortcomings. In addition to high cost, there are still a lot of basic work in all aspects of digital control technology, heat dissipation, magnetic isolation, electromagnetic interference, zero position, increased thrust, reduced energy consumption, and modularization of components. do.

Due to the excellent rolling friction characteristics and high transmission efficiency (η=90%~95%) and the agile and flexible function of the ball screw pair, it has the advantage of speed increase. Therefore, compared with the linear motor, the precision high-speed ball screw pair not only has the advantage of low cost, but also facilitates full digital control, easy cooling, low heat generation, no electromagnetic radiation, large axial thrust, high transmission efficiency, The modularization of components has matured, and in many fields, linear motors cannot be replaced or cannot be replaced for a long time.