Planetary roller screw
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PLANETARY ROLLER SCREWS ASSEMBLY TECHNICAL INTRODUCTION 176-183 • Roller Screw Design 176-177 • Calculation and Selection 178-180 • Lubrication and Maintenance 181 • Accuracy and Installation 182 • Reference Number System 183 PLANETARY ROLLER SCREWS AND NUT TECHNICAL DATA 184-191 • One-piece and Split Cylindrical Nut 184-187 • One-piece and Split Flanged Nut 188-191 EZZE-MOUNT™ EZRF BEARING SUPPORTS TECHNICAL DATA 192 MKR LOCKNUT TECHNICAL DATA 193 NOOK NRS™ Planetary Roller Screws The specifications and data in this publication are believed to be accurate and reliable. However, it is the responsibility of the product user to determine the suitability of Nook Industries products for a specific application. While defective products will be replaced without charge if promptly returned, no liability is assumed beyond such replacement. nookindustries.com NRS Planetary Roller Screws ™

Planetary Roller Screws Nook Planetary Roller Screws (NRS), a member of the lead screw family, are remarkable devices designed to convert rotary motion into axial force or vice versa. The NRS design offers multiple advantages and reliability for the most demanding applications when compared with other lead screw types due to its rolling motion. NRS offer high effi ciency even in relatively shallow lead designs. The multitude of contact points can carry large loads and provide very high resolution (small axial movement) when using very shallow leads. NRS produce high rotational speeds with...

Planetary Roller Screws PRELOADED NRS Split nuts are installed with two halves pushed against each other and the clearance removed for preload. Due to the large number of contacts and great rigidity, a planetary roller screw does not require high preload amounts to perform backlash-free in most application conditions. Split nuts only carry load on a reduced length of thread (half length minus the half-thickness of the calibrated spacer). NON-PRELOADED NRS One-piece solid nuts do not have a calibrated spacer to remove backlash. One-piece nuts have larger load ratings since all threads of the...

Planetary Roller Screws CRITERIA FOR SELECTION OF ROLLER SCREWS HIGH STATIC LOAD: Static load ratings as high as 9,500 kN are available SMALL LEAD APPLICATIONS: Leads of 1mm are available with a screw diameter of 50mm HIGH LINEAR SPEEDS: Linear velocities of 120 m/min or higher are possible with high lead screws HIGH LINEAR AND ANGULAR ACCELERATION: Tests have been successfully conducted with angular accelerations of 7,000 radians/s2 SHOCK LOADS OR ADVERSE ENVIRONMENTAL CONDITIONS: Roller screws kept operating in tests with poor lubricating conditions and after ingesting ice and sand...

Planetary Roller Screws Fixed - Free: fe = 1/L L Equivalent load Operating loads can be defi ned by physical characteristics (i.e. masses, inertia, etc.) that operate on the screw. For systems with varying conditions, such as changes of load magnitude and duration as well as speed, the simple calculation cannot be employed and an equivalent load should be assessed. The equivalent load is a calculated mean operating load used for determining life and is dependent upon load pattern. The equivalent load can be computed using the following formula: P = 3 q1xn1xFax1 3+q2xn2xFax2 3+…+qnxnnxFaxn 3...

Planetary Roller Screws The nut rigidity can be calculated as follows: Cän = f 3 n x Fax The factor fn can be supplied upon request. The customer must determine the rigidity of the bearings and housing. Column strength If the screw is subjected to compressive loads, then a verifi cation of its suitability to the loading conditions can be performed as follows: Fax allowed = fsc x do 4 x 104 L2 Where: fsc = factor dependent on end-support confi guration (see table below) do = screw nominal diameter L = free-length Critical speed The maximum achievable rotational velocity of planetary roller...

Planetary Roller Screws Where: nmax = allowable screw rotational velocity (RPM) fsn = factor dependent upon the end-support confi guration (see table on previous page) do = screw nominal diameter L = screw free-length Effi ciency and driving torque Effi ciency of the NRS planetary roller screw is dependent upon its operating parameters. The friction of the system is dependent upon varying factors that cannot be easily summarized here. To simplify the selection of the screw size, the following formulae can be used. ç1 = 1 1+ ff x do pho for transforming rotary motion in axial motion ç2 = 1-...

Planetary Roller Screws ACCURACY NRS planetary roller screws are produced in quality classes according to ISO 1, 3 and 5 standards. The summary of the characteristics and their allowable error are reported below. INSTALLATION NRS planetary roller screws are precision components. They must be handled with care before and during installation to prevent the units from carrying radial loads or moments since either of these will impair the proper functioning and reduce the life of the system. Nook engineers are at your disposal to address any concerns for the design of the adjacent construction...

Planetary Roller Screws HOW TO ORDER To generate a part number for ordering a NRS planetary roller screw assembly, specify the correct designations from the chart, see examples below. For further assistance contact our engineering department. Examples: NRS B 12x5-300/500 2W R G3 12x5 Right Hand Roller Screw, accuracy class of ISO 3, with a One-piece Cylindrical Nut with 2 wipers. 300mm of threaded screw with an overall length of 500mm. NRS SF 30x25-1200/1600 NW L G1 30x25 Left Hand Roller Screw, accuracy class of ISO 1, with a Split Flanged Nut without wipers. 1200mm of threaded screw with...

Planetary Roller Screws Nominal Screw Dia. Dia. x Lead Lead g6 D1 D7 d0 Ph0 D8 1 0 = = d D 15.. = = d 21 mm L1 L D7 b H9 h D8 L 2* L 1 L D1 d0 d 21 mm Nook Planetary Roller Screws are used in the most demanding and precise linear motion applications. With a greater number of contact points a roller screw provides stiffness and higher load ratings compared to a ball screw. *Note: Dimensions with wipers available by request. kN x 224.82 = lbs WITH WIPERS WITHOUT WIPERS 8 NRS 8x2 2 21 3 - NRS 8x4 4 21 3 - 12 NRS 12x2 2 26 3 - NRS 12x4 4 26 3 - NRS 12x5 5 26 3 - 15 NRS 15x2 2 34 3 - NRS 15x4 4...