Roller screws - SKF

1 Roller screws SKF is a registered trademark of the SKF Group. SKF Group 2014 The contents of this publication are the copyright of the publisher and may not be reproduced (even extracts) unless prior written permission is granted. Every care has been taken to ensure the accuracy of the information contained in this publication but no liability can be accepted for any loss or damage whether direct, indirect or consequential arising out of the use of the information contained MT/P1 14489 EN April 2014 This publication supersedes publication image(s)

2 Used under license from Selection planetary Roller screws Ultra Power Roller screws inverted Roller screws Rotating nut with planetary Roller screws Recirculating Roller screws Support bearings FLRBUC Calculation formulae and exampleD Recommendations for assemblyE Additional informationContentsA Product informationSKF the knowledge engineering company .. 4 Selection guide .. 6 planetary Roller screws SR/BR, HR .. 6 planetary Roller screws PR, with internal preload .. 8 inverted Roller screws ISR/IBR.

3 10 Rotating nut Roller screws SRR/BRR .. 10 Recirculating Roller screws SV/BV .. 11 Recirculating Roller screws PV, with internal preload .. 11 Preferred range .. 12 Introduction to Roller screws .. 14 SKF Roller screws , high performance driving solutions .. 14 Typical applications for Roller screws .. 16 Roller screws conceptual design advantage over ball screws .. 18 Technical concepts .. 19 Introduction to SKF Roller screws .. 19 Basic dynamic load carrying capacity .. 19 Nominal fatigue life.

4 19 Service life .. 20 Equivalent dynamic load .. 20 Basic static load carrying capacity .. 20 Critical rotating speed for screw shafts .. 21 Permissible speed limit and acceleration .. 21 Efficiency .. 22 Back driving and braking torque .. 23 Break away torque .. 23 Driving torque .. 23 Static axial stiffness .. 23 Materials, heat treatment and coatings .. 24 Operating temperature .. 25 screw shaft buckling or column strength .. 25 Shaft design .. 26 Product inspection and certification.

5 27 Working environment .. 27 Lubrication .. 28 Lubrication for Roller screws .. 28 Grease lubrication .. 29 Oil lubrication .. 34 Wipers .. 34 Dry lubricants .. 34 Axial play and preload .. 36 Axial play and preload .. 36 Preload and stiffness .. 36 Preload torque .. 38 Preload torque tolerances .. 38 Preload adjustment .. 40 Lead precision and manufacturing tolerances .. 42 Lead precision .. 42 Manufacturing tolerances .. 46B Product dataPlanetary Roller screws SR.

6 50 SRC/BRC planetary Roller screws with cylindrical nut .. 52 SRF/BRF/SRP/BRP planetary Roller screws with flanged nut .. 58 PRU preloaded planetary Roller screws with cylindrical nut .. 64 PRK preloaded planetary Roller screws with flanged nut .. 70 Ultra Power Roller screws HR.. 74 HRC Ultra Power Roller screws with cylindrical nut .. 76 HRF/HRP Ultra Power Roller screws with flanged nut .. 80 inverted Roller screws ISR .. 84 Rotating nut with planetary Roller screws SRR .. 88 SRR/BRR planetary Roller screws with rotating nut.

7 90 Recirculating Roller screws SV .. 92 SVC/BVC recirculating Roller screws with cylindrical nut .. 94 SVF/BVF recirculating Roller screws with flanged nut .. 96 PVU preloaded recirculating Roller screws with cylindrical nut . 98 PVK preloaded recirculating Roller screws with flanged nut .. 1002 Support bearings FLRBU .. 102 FLRBU support bearings with angular contact ball bearings .. 104 Standard machined ends .. 105 Recommendations for support bearings assembly and orientation .. 106 Support bearings recommended for standard planetary Roller screws .

8 107 Support bearings recommended for recirculating Roller screws .. 108 Preselection of spherical Roller thrust bearings .. 109C Calculation formulae and exampleCalculation formulae .. 111 Calculation example .. 114D Recommendations for assemblyHandling, storage, nut disassembly, support bearing assembly, alignment .. 117 Alignment .. 120E Additional information .. 122 Technical request form .. 122 Symbols .. 124 Electro mechanical cylinders .. 126 Linear Motion solutions .. 131 Designation system.

9 1323 From one simple but inspired solution to a misalignment problem in a textile mill in Sweden, and fifteen employees in 1907, SKF has grown to become a global industrial knowledge leader. Over the years, we have built on our exper-tise in bearings, extending it to seals, mecha-tronics, services and lubrication systems. Our knowledge network includes 46 000 employees, 15 000 distributor partners, offices in more than 130 countries, and a growing number of SKF Solution Factory sites around the world.

10 Research and development We have hands-on experience in over forty industries based on our employees know-ledge of real life conditions. In addition, our world-leading experts and university part-ners pioneer advanced theoretical research and development in areas including tribol-ogy, condition monitoring, asset manage-ment and bearing life theory. Our ongoing commitment to research and devel opment helps us keep our customers at the forefront of their industries. Meeting the toughest challenges Our network of knowledge and experience, along with our understanding of how our core technologies can be combined, helps us create innovative solutions that meet the toughest of challenges.