In 1845, the British had invented the linear motor, but at that time the linear motor air gap was too large, resulting in low efficiency, unable to apply. Colmorgan also launched it in 1870s, but its development was limited by high manufacturing cost and low efficiency.

It was not until the 1970s that linear motors were gradually developed and applied in some special fields. In the 1990s, linear motors began to be applied in the machinery manufacturing industry. Now some technologically advanced machining center manufacturers in the world began to apply them in their high-speed machine tools, using high-speed and high-precision machining centers of linear motors.

The following makes some comparison on several main characteristics of linear motor, to provide a reference for the relevant industry.

1. Speed comparison

In terms of speed, linear motor has considerable advantages. The speed of linear motor reaches 300m / min and the acceleration reaches 10g; The speed of the ball screw is 120m / min and the acceleration is 1.5g. In terms of speed and acceleration, linear motor has considerable advantages, and the speed of linear motor will be further improved after successfully solving the heating problem, while the speed of "rotary servo motor + ball screw" is limited, so it is difficult to improve more.

In terms of dynamic response, linear motor also has great advantages because of inertia, clearance and complexity of mechanism. In speed control, because of its fast response and wider speed range, linear motor can achieve instant speed at start-up, and stop quickly at high speed. The speed range can reach 1:10000.

2. Accuracy comparison

In terms of accuracy, because the linear motor drive mechanism is simple, and the problem of interpolation lag is reduced, the positioning accuracy, reproduction accuracy and accuracy are higher than that of "rotary servo motor + ball screw" through position detection feedback control, and it is easy to realize.

The positioning accuracy of linear motor can reach 0.1 μ m。“ Rotating servo motor + ball screw "to 2 ~ 5 μ m. If we want to achieve higher stability, "rotary servo motor + ball screw" should be driven by two axes, linear motor is a high heating part, so we need to take strong cooling measures. To achieve the same goal, linear motor has to pay a greater price.

3. Price comparison

In terms of price, the price of linear motor is much higher, which is also the reason why linear motor is more widely used.

4. Energy consumption comparison

The energy consumption of linear motor in providing the same torque is more than twice that of "rotary servo motor + ball screw". The "rotary servo motor + ball screw" is an energy-saving and force increasing transmission component. The reliability of linear motor is affected by the stability of the control system, which has a great impact on the surrounding environment. Effective magnetic isolation and protection measures must be taken, The influence of strong magnetic field on rolling guide and the adsorption of iron dust are separated.

5. Application Comparison

Linear motor drive has unique advantages in the following areas of CNC equipment: high speed, ultra-high speed, high acceleration and large production volume, many movements requiring positioning, frequent changes of speed and direction. For example, the production line of automobile industry and it industry, the manufacturing of precision and complex mould.

"Rotary servo motor + ball screw" is widely used in large-scale, ultra long stroke high-speed machining center, aerospace manufacturing industry, light alloy, thin-walled, metal removal rate of the whole component "hollow" processing. It requires high dynamic characteristics, low speed and high speed follow-up, high sensitive dynamic precision positioning, light load and fast special CNC equipment.

In the future, the technology of linear motor will be more mature, the output will be increased, the cost will be reduced, and the application will be more extensive. However, from the perspective of energy saving and green manufacturing, as well as the characteristics of the two structures, the "rotary servo motor + ball screw" drive still has a broad market space.