Linear motor provides alternative to leadscrew positioning

Oct. 24, 2002
The linear motor develops its drive force through interactions between fixed and electrically generated magnetic fields.

Some manufacturing companies have been hesitant to change from leadscrews to linear motors on automated assembly lines because of the difficulty integrating linear motors into their automation systems and their need for more for cooling. Thrust Rods from Copley Controls Corp., Canton, Mass. (, eliminates these concerns.

Loads mount directly on a thruster, just as they mount on a leadscrew platform. This makes upgrading from leadscrews easier. And a large gap between the thruster and rod, one that lets the rod travel friction free, lets in cooling air. There are also cooling fins on the surface of the thruster

A stationary field is set up by permanent magnets in the thrust rod. The moving field is generated by electromagnets in the forcer, the device's only moving part. All magnetic lines of force created by the forcer engage all the lines of force created by the thrust rod, so the motors deliver more force per amp than conventional drives. Among the eight standard models, peak force is 890 lb, peak acceleration is 772 m/sec2, peak velocity is 14.5 m/sec, and all can be equipped with position encoders with resolutions of 0.1 mm.

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