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Multiple linear motors controlled independently on common axis

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Multiple linear motors controlled independently on common axisCopley Motion Systems claims to have pioneered the use of multiple linear motors sharing the same axes to provide unparalleled performance while saving machine space.

The tubular linear motor, which was originally designed by Copley, is inherently well balanced because the symmetrical design eliminates attractive forces; mechanical integration is therefore said to be simpler. More importantly, however, Copley believes the ServoTube range of linear motors and actuators is the first to use an integrated position sensor. As a result, an external encoder strip is not required, which enables two or more forcers to operate on the same magnetic rod.

This use of multiple forcers makes the ServoTube motor very versatile. A dual forcer stage can provide independent control of both forcers, so that two independently controlled forcers can double productivity. With each motor controlled by its own drive amplifier, totally independent motion is possible. The forcers can travel in unison or in opposite directions, so, for example, one linear motor can be programmed to load parts while the other unloads them.

In a recent application, a packaging machinery customer used three ServoTube linear motors to independently reposition bottles 'on the fly' as they were moved in batches of three between a labelling machine and a bottle capping machine with incompatible conveyor systems. The Y axis repositioning was achieved by the three linear motors operating simultaneously while bolted to a ServoTube X axis that moved the bottles between the two machines at the same time. A significant increase in performance was achieved through executing several operations in parallel.

Double or triple force

Another feature of the drive stage is that two - or three - forcers can be mounted on a single rod to double - or triple - the drive force.

The efficient design of the ServoTube motor minimises heat dissipation, thereby eliminating the need for forced-air cooling. While proper ventilation of the machine is essential, the elimination of forced cooling can further simplify machine design and save space.

The linear motor is available in 25mm and 38mm diameter rod models, with different coil configurations to meet the required force and speed of the application.

Both the ServoTube linear motor and the moving rod ServoTube linear actuator provide high-speed, out-of-the box positioning when combined with the Xenus digital servo amplifier or a compatible sinusoidal servo amplifier.

 
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