Application of linear motor on high speed machine tools

With the development of direct drive technology, the comparison between the linear motor and the traditional "rotary servo motor ball screw" drive mode has attracted industry attention. Now some of the world's most advanced machining center manufacturers are beginning to apply on their high-speed machine tools.

In terms of accuracy, the linear motor has a simple reduction of the interpolation hysteresis due to the transmission mechanism. The positioning accuracy, the reproduction accuracy, and the absolute accuracy are higher than the "rotary servo motor ball screw" by the position detection feedback control, and are easy to implement. Linear motor positioning accuracy can reach 0.1μm. "Rotary servo motor ball screw" up to 2~5μm, and requires CNC-servo motor-no-gap coupling-thrust bearing-cooling system-high-precision rolling guide-nut seat - Workbench closed-loop The transmission part of the whole system should be lighter and the grating accuracy should be high. If you want to achieve high stability, the "rotary servo motor ball screw" should be driven by two-axis. The linear motor is a high-heating component, and it needs to adopt strong cooling measures. To achieve the same purpose, the linear motor has to pay a higher price.

In terms of speed, 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 1.5g. From the comparison of speed and acceleration, the linear motor has considerable The advantage, and the linear motor will further improve the speed after successfully solving the heating problem, and the "rotary servo motor ball screw" is limited in speed and it is difficult to improve more.

In terms of life, the linear motor has a mounting gap between the moving part and the fixed part, has no contact, and is not worn by the high-speed reciprocating motion of the mover. The long-term use has no change in the positioning accuracy of the motion, and is suitable for high-precision occasions. The ball screw can not guarantee the accuracy in high-speed reciprocating motion. Because of high-speed friction, the screw nut will wear and affect the accuracy of the motion. The demand for high precision cannot be met.