Stretch a carpet an extra inch, save $100,000. That was what a manufacturer of ready-to-mount automotive carpeting was trying to accomplish with a linear-motion system used in its manufacturing process.
Operations begin with workers manually laying a top layer of carpeting over a mold having a pad set into it. The linear system, containing bearings and a carpettack- filled pneumatic actuator, then can grab and then stretch the carpet. The motion system must be strong enough to work continuously.
Initially, profiled slider rails in the system would wear out in only about three months. It took about two weeks to change them, during which production came to a halt.
Contamination and a high cantilever turned out to be the two main reasons for failure. Carpet fibers were finding their way into the recirculating ball tracks and plugging them up. The facility was spending an average of $104,000 every year in replacement costs.
A Compact Rail linear-bearing system from Rollon Corp., Sparta, N.J., solved the problem. It has raceways on the inside of the rails as protection from damage and contaminants. This feature also lets the rail and slider mount into small, compact, areas. Built-in, spring-loaded wipers in the heads and the lateral seals on the sides of the slider ensure operation in superdirty environments. These ‘Lubed for Life’ wipers continually deposit a thin film of oil on the races. Individual sliders can carry up to 3,300 lb and can move up to 9 m/sec.
Compact Rail also absorbs rotational positioning errors, misalignments between lateral planes, longitudinal parallelism errors, or a combination of all of these while still maintaining the system’s original preload setting. It is designed to provide smooth movement whether mounting plane parallelism can be guaranteed or not. After more than three years, the Compact Rail systems are still running on the manufacturer’s 50 molds with no need for replacement.
An artist’s depiction of a carpet stretching mechanism shows the linear rails on which the moving station travels.
In real life, the Rollon linear-rail installation looks like this. The inset details the raceways on