Comparison of properties of linear motor and ball screw
time：2011/7/28 click：8031
With the development of direct drive technology, the contrast between linear motor and traditional "rotary servo motor + ball screw" has attracted the attention of the industry. In the 1990s, linear Motors began to be used in the mechanical manufacturing industry. Now some advanced processing center manufacturers in the world have begun to apply their high-speed machine tools.
Accuracy comparison:
In terms of precision, the linear motor simply reduces the problem of interpolation lag due to the transmission mechanism. The positioning accuracy, recurrence accuracy, and fixed precision are all higher than the "rotating servo motor + ball screw" through position detection feedback control, and are easy to achieve.
The positioning accuracy of the linear motor can reach 0.1 μm. The peak of "rotating servo motor + ball screw" reached 2 ~ 5 μm, The CNC-servo motor-no-gap coupling-stop bearing-cooling system-high-precision rolling guide rail-nut seat-work station closed-loop transmission part of the entire system should be lightweight, grating accuracy should be high.
If you want to achieve higher stability, "rotating servo motor + ball screw" to take a two-axis drive, linear motor is a high-heating component, need to take strong cooling measures, to achieve the same purpose, linear motor will pay a greater price.
Speed comparison:
The speed of the linear motor has considerable advantages. The linear motor speed reaches 300m/min and the acceleration reaches 10g; The ball screw speed is 120m/min and the acceleration is 1.5 G. Compared with the speed and acceleration, the linear motor has considerable advantages, and the linear motor will further increase its speed after successfully solving the heating problem, while the "rotary servo motor + ball screw" is limited in speed. It is difficult to increase more.
In dynamic response, linear Motors also have an advantage because of problems such as motion inertia and clearance and mechanism complexity.
Because of its fast response and wide speed range, the linear motor on speed control can achieve peak speed at the moment of start-up, and can quickly stop at high speed. Speed range can reach 1:10,000.
Life comparison:
In terms of life, the linear motor has a gap between the moving parts and the fixed parts. There is no contact, and it will not be worn due to the high-speed reciprocating movement of the movers. The accuracy of the motion positioning is not changed in the long time, and it is suitable for high-precision situations. Ball screw can not guarantee precision in high-speed reciprocating motion. Because of high-speed friction, it will cause the wear of the screw nut and affect the accuracy of the motion. The demand for high precision can not be met.
Linear motor