Motors & Drives Information

A versatile solution requires only one moving part.

The term "linear motor" is often used to describe "flat" linear motors, where essentially one flat plate is moved across the face of another. It is also used to describe motors that provide linear motion using some form of internal rotary-to-linear conversion. But now California Linear Devices has developed a tubular linear motor that provides the required axial force in a simple device with one moving part. This unit has many applications, ranging from motion control to welding, riveting, vibrating and driving compressors. With only one moving part the inherent reliability is high.

The motor is also suited to positioning applications. Through the use of a precision, high-resolution encoder, one can rely on detailed position information to a motion controller.

The basic principle on which this motor operates is as follows. The linear motor has a stator very similar to that of an induction motor. Windings are placed in slots throughout the periphery. Their purpose is to produce a moving magnetic field. The armature has a series of permanent magnets that attempt to align themselves with this moving magnetic field. The force level is set by the length and diameter of the stator, and the stroke is set by selecting the length of the armature.

Recently California Linear Devices undertook a program to show that, in relatively low-force material-testing applications, such a simple direct-drive linear motor can do a better, simpler, and cleaner job than a hydraulic system. It was considered that in the region under 2,000 lb. of force the use of a simple one-moving-part linear motor might be more controllable and easier to operate and maintain than a hydraulic control system. The program intended to demonstrate this with a goal of under 1% accuracy at 340 lb. force, with the ability to vary the load as demanded by an operator or through a PLC system input.

# posted by Medical Information : 4:41 AM