Planetary roller screws provide significant benefits ov […]
Planetary roller screws provide significant benefits over other screw-type actuators in terms of performance, load capacity, duty cycle, and lifetime. Traditionally, however, those benefits have come along with significantly higher prices and lead times. As a result, the technology was typically saved for applications that had to have performance, no matter what the price. This article will explore the development of Tolomatic’s roller screws as a case study.
Along with manufacturing partner Motion Solutions, Tolomatic has released a family of U.S.-made roller screws that cut pricing and reduced lead times to as little as two weeks. The product line enables engineers designing general industrial automation equipment to gain the performance advantage of roller screws.A planetary roller screw combines characteristics of a standard screw-type actuator with the configuration of a planetary gearbox. Many variations exist, but the most general type consists of a nut that travels relative to the screw.
Instead of recirculating balls, the interface between the threaded nut and the screw consists of a series of rollers arranged around the screw in a planetary fashion. The nut threads mesh with the roller threads, and the roller threads mesh with the threads of the screw.In a planetary roller screw, the nut is lined with a planetary arrangement of rollers. The rollers reduce friction while significantly increasing contact area.
enabling roller screws to support greater loads, higher duty cycles, longer lifetimes, and better accuracy and repeatability than other screw-type actuators.The design significantly increases surface contact. As a result, a planetary roller screw can handle a much higher load in a smaller package than (for example) a ballscrew. This characteristic makes them very effective in applications with size or weight limitations. Roller screws are also much more robust than competing technologies, enabling them to handle very high-duty cycles and achieve long lifetimes.
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