Rolamite bearings, originally designed for NASA with an order of magnitude of friction lower than ball bearings, can generate cog-free linear motion. A carriage is propelled along a track under the influence of a servomotor coupled to a Rolamite bearing through a worm drive. This is a new way to think about linear motion mechanics.
The bearing is formed from rollers constrained by a tension band wrapped in an S configuration and perforated to prevent slippage and thus provide precise position control. A double S wrap insures the complete conversion of pure rolling motion to ripple-free linear motion. The band is fabricated from Mylar film or stainless steel. A linear scale and encoder govern the positioning. The payload is mounted to the carriage for stage or gantry-type actuation or to the housing for pick and place.
Typical linear actuators contain a lead screw and linear ball slide requiring lubrication. These components are eliminated by a Rolamite bearing which requires no lubrication. The Rolamite actuator integrates the drive and bearings into one monolithic structure that reduces complexity, cuts cost in half, and increases life expectancy since most friction is eliminated. A typical small payload (under 2 lbs) can be powered by a 5W motor. Nominal speeds can range up to 20 inch/sec with strokes as desired.
An aluminum extrusion combines the housing and guide, resulting in a lightweight, compact unit. Potential applications include payloads under 10 lbs ranging from positioning stages to clean rooms to pipetting drives and 3D printers.
Donald Rich has developed pioneering technologies for Intel, IBM, Digital Optics, Data IO, Protodyne, Parlex, RVSI, and BP Micro. As the CEO and Chief Engineer of IntellePro, he developed ultra-compact, high-speed, lightweight, reliable pick-and-place heads for the semi-conductor and biotech industries.