New Planetary Screw Assemblies: Stronger but Quieter and More Compact

New Planetary Screw Assemblies: Stronger but Quieter and More Compact

The new planetary screw assemblies move heavy loads quickly.

Rexroth pushes into the upper performance classes of screw assemblies

With newly developed planetary screw assemblies, Rexroth is expanding the range of applications for electro-mechanical solutions by a solution that allows for heavy loads to be moved quickly. The drive elements are available in five sizes. They reach a static load capacity of up to 475kN, while at the same time requiring less installation space than ball screw assemblies having the same capacity. The high performance drive elements are especially well-suited for intermediate and heavy engineering applications, such as pressing, machine tools and plastic injection-molding machines.

The design principle of planetary screw assemblies with large contact areas improves the load bearing capacity significantly without increasing the dimensions. Planetary gears with a defined contact profile rotate inside a nut parallel to the axis around a bolt. The numerous contact areas lead to a high axial rigidity and load bearing capacity, thereby allowing for a long service life. The new screw assemblies achieve a high level of positioning and reproduction precision even with minimal movement.

Contrary to ball screw assemblies, where the balls are continuously fed back through the return passage into the load bearing area, the planetary bolts rotate inside the nut. This makes them run very smoothly, with noise emissions remaining clearly below those of ball screw assemblies.

Rexroth's sealing technology in the planetary screw assemblies allows for long lubrication intervals. As a result, lubricant consumption is reduced, which in turn means lower maintenance costs and less pollution.

The product range initially includes screw diameters of 20, 30 and 48 mm and leads of 5 and 10 mm. Compact cylindrical single nuts and flange single nuts grant a high degree of freedom for designers. With the new planetary screw assemblies, Rexroth covers dynamic load capacities of up to 231kN and static load capacities of up to 475kN. In addition, a split flange single nut allows for the assembly to be preloaded for zero clearance.

In manufacturing the screws, Rexroth benefits from its experience in the economical roll-forming process. This technology, which has proven successful in large series production, achieves the same accuracy levels as the more expensive grinding process. Rexroth supplies the planetary screw assemblies ready-to-install with machined ends.

Bosch Rexroth Canada is the Canadian subsidiary of Bosch Rexroth AG, one of the world’s leading specialists in the field of drive and control technologies. Under the Rexroth brand name, the company supplies more than 500,000 customers with tailored solutions for driving, controlling, and moving. Bosch Rexroth is a partner for Mobile Applications, Machinery Applications and Engineering, Factory Automation and Renewable Energies. The company provides customized solutions tailored to the needs and specifications of each individual market. As The Drive & Control Company, Bosch Rexroth develops, produces, and sells components and systems in over 80 countries. As part of the Bosch Group, Bosch Rexroth and its 34,900 associates generated approximately 5.1 billion euros in revenue in 2010.

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The Bosch Group is a leading global supplier of technology and services. In the areas of automotive and industrial technology, consumer goods, and building technology, some 285,000 associates generated sales of 47.3 billion euros in fiscal 2010. For 2011, the company forecasts sales of more than 50 billion euros ($70 billion) and a headcount of 300,000 by the end of the year. The Bosch Group comprises Robert Bosch GmbH and its more than 350 subsidiaries and regional companies in over 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. Bosch spent 3.8 billion euros for research and development in 2010, and applied for over 3,800 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial.

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