SPIETH Locknuts Series MSW Works Standard SN 0.03
SPIETH Locknuts Series MSW SPIETH locknuts offer a range of technical benefits, qualified by their special system and production. Under high levels of dynamic stress, the good axial rigidity, high axial load capacity and the outstanding locking properties offered by this locknut series are of decisive importance. Simple connecting elements, no grooves, locking plates etc. The nut used for mounting roller bearings plays an important part in determining the quality of the entire bearing. The locknut contact surface can be adjusted simply and precisely at any axial position. The produced high standard of run-out accuracy is retained when mounted and can be improved if necessary by setting individual adjustment. Functional principle: Screwing on the locknut, the existence of thread flank play allows the nut to tilt. The contact surface of the nut can come to rest positioned at an incline. The principle is shown in a simplified diagram with enlarged thread flank play. Thread flank play eliminated, the locknut is centered and can no longer tilt. The nut s contact surface has aligned at right-angles to the spindle axis. 2
SPIETH locknut series MSW Execution up to MSW 70. SPIETH locknut series MSW Execution from MSW 72.0 Fields of application: MSW series locknuts are precision nuts capable of absorbing extremely high axial forces. As a result, they are ideally used in applications involving pretensioned roller bearings with high load capacity, such as axial cylindrical roller bearings. However, they can also be used to create other nut connections subjected to high levels of stress, for example on press frames, hydraulic cylinders, testing machines etc. The precision, high axial rigidity and high level of dynamic safety of these locknuts offer the user a range of technical benefits which make a major contribution to trouble free overall running. Benefits: The locknut is designed rotationally symmetric without any imbalancing properties such as grooves, slots etc. The clamping screws distributed evenly around the centre (in a circle) together with the ideally configured elastic diaphragm of the locknut will result in even clamping forces all around the spindle thread. These clamping forces ensure intensive contact between the thread flanks of the nut and spindle, resulting in a high degree of axial rigidity around the entire periphery of the nut (eliminating soft spots). Adaptation of little imperfect shapes and surface compression on the thread occurring in conventional nuts as a result of subjection to operating loads are anticipated by the design feature of the SPIETH lock-nuts. The resulting reduction in axial pretension caused by the named anticipation is simply compensated during mounting by applying a higher moment of pretension. The end face of the locknut can be aligned until completely free of play. Little errors in the run-out accuracy of the connecting components can be compensated if necessary by individual adjustment of the clamping screws. Unilateral tensions are often the cause of poor concentricity in mounted spindles. Despite a spindle thread produced to ISO standards, flank play can be restricted during mounting right down to zero, so permitting precision adjustment of the locknut's contact surface. 3
Execution: These locknuts are generally required to withstand high pretension forces. In the upper dimension range, these pretension forces can no longer be achieved in practice using the locknut s own pretension moment due to the size of the friction radii. For this reason, the MSW locknut series is divided into two different executions: Up to locknut size MSW 70., axial pretension is set by using the pretension moment of the locknut, from size MSW 72.0 upwards using the tightening torque of the integrated set screws. Both types are produced in steel, tempered and burnished. The metric ISO thread is manufactured to the tolerance class fine (tolerance dass 5H, DIN 13, parts 21-25) in a single work process together with the end face of the locknut. Connecting components: Fig. 3: A hardened gear can assume the function of a thrust collar. Locknut execution to MSW 70. (Fig.1) Grooves designed to accommodate a DIN 0 form A sickle spanner are provided for the screwing on and pretension of this locknut size. The integrated clamping screws are cheese-head screws to ISO 72. Fig. 1 Clamping screw The metric bolt thread must be produced to tolerance class fine (tolerance class h, DIN 13, parts 21-25). The contact surfaces of the connecting components are essential to optimum Fig. : An unhardened toothed belt pulley can be used as a thrust collar with a hardened disc placed in-between. Locknut execution from MSW 72.0 (Fig.2) This locknut size is screwed on manually or using a socket wrench in the radial boreholes placed around the periphery. The clamping screws (cheese-head screws to ISO 72) are used to secure the locknut. The nut pretension is carried out using set screws (threaded pin to ISO 02), which are then blocked using radial arranged aluminium thrust bolts and locking screws (threaded pin to ISO 02). Fig. 2 Locking screw Aluminium thrust bolt Set screw Clamping screw function and must be manufactured with particular care and precision. To avoid surface seizure, the finish of the contact surfaces should have a level of surface roughness as low as possible. From locknut size MSW 72.0 For this locknut size, the axial pretension applied by the hardened threaded pins requires a specially configured thrust collar to absorb the high local pressure loads. The thrust ring must be hardened. The reason for the prescribed minimum height is to ensure distribution of locally occurring pressure forces to the following end contact surface. In certain cases, an already existing machine component, such as a gear, may be able to assume the function of the thrust collar (Fig. 3 + ).
Explanations Clamping screws: Set screws: Setting an axial pretension force: Cheese-head screws with a hexagon socket in compliance with ISO 72. M A : Tightening torque per clamping screw. The tightening torque is based on a friction coefficient of µ= 0.1. Hexagon socket set screws to ISO 02 with dog point. The axial pretension of a screw connection often plays a decisive role for successful function, and must therefore be set with particular accuracy. However, in most assembly workshops, direct measurement of this variable is not possible, raising the need for indirect methods of setting. For this purpose the locknut pretension moment is calculated corresponding to the required pretension force. This factor can be determined using the following formula: As the effective friction coefficients depend on a range of factors which are often beyond the control of the manufacturer, values specified here are without commitment and are made in the form of recommendations. M D : Tightening torque per set screw. This value is ascertained in accor dance with the required pretension force. The locking process strains the spindle thread with the effect of an intensive surface contact (= high axial rigidity). At the same time, this serves to relieve tension on the end contact surface of the locknut. This effect can be simply compensated by setting an increased pretension torque during mounting. This higher pretension torque is ascertained using the allowance B relative to the required pretension force Fv. Up to locknut size MSW 70.: Mv = (Fv + B) (A + µ A r A ) [Nm] 00 Mv = Pretension moment of the locknut [Nm] Fv = Required axial pretension force of the screw connection [N] B = Locknut-specific allowance [N], compensates end-face relief caused by the locking process A = Constant [mm], includes the calculation factors for the respective thread diameter (see table) µ A =Friction of coefficient for the end contact surface of the locknut. Approximate value µ A = 0,1 steel/steel r A =Effective friction radius for the end contact surface of the locknut [mm] From locknut size MSW 72.0: The tightening torque for the set screw is determined according to the following formula: M D = Fv ( A + µ D d ) [Nm] 32000 M D =Tightening torque per set screw [Nm] Fv = Required axial pretension force of the screw connection [N] A = Constant [mm], includes the calculation factors for the respective thread diameters (see table) µ D =Friction of coefficient for the end contact surface of the locknut. Approximate value = 0.13 d = Dog point dia. of the compression screw [mm], (see table) 5
SPIETH Locknuts Series MSW Designation of a locknut with d 1 =M 30 x 1,5 and height h = 2 mm: Locknut MSW 30.2. The admissible operating loads specified in the table are guideline values calculated with a safety factor of 1. under static stress relative to the minimum yield point, under dynamic stress relative to the minimum alternate strength. Subject to changes. Special versions: On request, by sending of an explanatory sketch. Code Dimensions in mm Clamping screws Calculation factor 1) d MSW 1 d 2 M d 3 h l b t ISO A No. 72 A Locknutspecific allowance B Adm. axial operating stress dyn. stat. Mass moment of inertia J ISO - 5H c Nm mm N kn kn kg cm2 20.2 25.2 30.2 35.2 0.2 5.2 50.32 20.0 25.0 30. 35. 0. 5. 50. 55. 0. 5. 70. M20x1,5 M25x1,5 M30x1,5 M35x1,5 M0x1,5 M5x1,5 M50x1,5 M20x1,5 M25x1,5 M30x1,5 M35x1,5 M0x1,5 M5x1,5 M50x1,5 M55x1,5 M0x1,5 M5x1,5 M70x1,5 2 7 52 0 5 70 75 52 2 73 75 90 95 0 0 0 5 3 3 53 5 3 2 7 52 0 2 70 75 0 5 90 95 2 2 2 2 2 2 32 0 0 12 12 12 12 7 7 7 2,5 3 3 3 M M M M M M M M M M M M M M M5 M5 M5 M5 1,3 1,33 1,921 2,2 2,500 2,79 3,079 1,3 1,33 1,921 2,2 2,500 2,79 3,079 3,39 5 3,9,23 150 150 150 150 150 230 230 93 93 93 93 93 22 22 22 22 57 77 97 5 17 0 131 172 195 215 23 2 272 29 31 333 0 2 123 1 15 1 27 15 19 273 320 37 50 551 59 5 0,0 0,719 1,053 1,03 2,259 3,132,775 1,701 3,125 5,5377 7,09 7,930 1,2 21,3395 29 2,792 35,05 2,2151 1) The number of grooves for sickle spanners DIN 0-A correspondents with the number of clamping screws.
ISO 02 ISO 02 Thrust bolt SPIETH Locknuts Series MSW ISO 72 Designation of a locknut with d 1 =M 72 x 1,5 and height h = 0 mm: Locknut MSW 72.0 The admissible operating loads specified in the table are guideline values calculated with a safety factor of 1. under static stress relative to the minimum yield point, under dynamic stress relative to the minimum alternate strength. Subject to changes. Special versions: On request, by sending of an explanatory sketch. Code d MSW 1 d 2 d 3 h l d 72.0 5.0 ISO - 5H M72x1,5 M5x2 Dimensions in mm Clamping screws Adm. axial operating stress c 135 95 0 0 0 1 1 5 12 d 5 Ø H No. ISO 72 M5 M M A Nm No. dyn. kn 07 stat. kn 79 50 Mass moment of inertia J kg cm2 0,1 21,131 Code Set screws Lock screws Aluminium thrust bolts MSW ISO 02-5H d M D 1) No. Calculation factor ISO 02 No. Ø Length No. mm Nm mm mm mm 72.0 5.0 M x 5 M 12 x 5 7,5 3 0 0,7575 0,9122 M x M x,5 3 3 1) Tightening torque recommended by screw manufacturer. Note: Other locknuts conforming to our works standard are available: SN 0.02 Series MSR SN 0.0 Series MSA with smaller outside dimensions for screw connections subject to lower stress levels. 7
Application: Fig. 5 Fig. Fig. 7 The locknut is deformable in the axial direction and must therefore be handled with care. The clamping screws should only be tightened when the locknut has been screwed completely onto the spindle thread. If these instructions are ignored, inadmissible plastic deformation could destroy the locknut. Mounting up to locknut size MSW 70. 1. Carefully clean the locknut and connecting elements and wet slightly with low-viscosity machine oil. 2. Screw the locknut onto the spindle thread. Wait before screwing it in completely (Fig. 1). 3. Tighten the clamping screws evenly in diagonal sequence while turning the locknut backwards and forwards, until flank play is almost eliminated (indicated by a tight fitting feel when turning the locknut Fig. 2).. Now tighten the locknut against the end contact surface initially by exerting a high level of torque. Then release again and finally tighten using the prescribed degree of torque (Fig. 3). This sequence prevents subsequent seizure at the contact surfaces (thread flanks, end contact surfaces). 5. Then secure the locknut by evenly tightening the clamping screws. Where stringent demands are made on spindle concentricity, it is possible to adjust the concentricity after testing by tightening the clamping screws individually. This method can also be used to eliminate any unilateral tensions caused as a result of minimal axial run-out errors in the connecting elements. Dismantling First relieve the tension of the clamping screws slightly in diagonal sequence. Only then should the clamping screws be completely released. This prevents the total tension of the diaphragm from working on the last clamping screw to be released and causing a jamming effect. Once a locknut has been secured on a spindle thread, after removal it may only be used again on the same spindle. Adjustment processes carried out between the spindle and locknut can otherwise lead to problems when using on a different spindle. A set of mounting instructions is provided with every delivery for firsttime users. Further copies can be provided on request.
Locking screw Mounting from locknut size MSW 72.0 1. Carefully clean the locknut and connecting elements and wet slightly with low-viscosity machine oil. Dismantling 1. Open the lock screws. First release the set screws lightly in the indicated sequence, then release completely. Fig. Set screw 2. Screw the locknut onto the spindle thread. Wait before screwing it in completely. The set screws should not be ahead the end face (Fig. ). 3. Tighten the clamping screws evenly in diagonal sequence while turning the locknut backwards and forwards, until flank play is almost eliminated (indicated by a tight fitting feel when turning the locknut Fig. 5).. Now screw the locknut against the end face until contact. Then tighten the clamping screws evenly to fix the locknut. 2. Release the clamping screws in diagonal sequence slightly before completely releasing. This prevents the total tension of the diaphragm from working on the last clamping screw to be released and causing a jamming effect. Once a locknut has been secured on a spindle thread, after removal it may only be used again on the same spindle. Adjustment processes carried out between the spindle and locknut can otherwise lead to problems when using on a different spindle. Fig. 9 Clamping screw 5. Now initially tighten the set screws with a high pretension moment in the indicated sequence step by step against the end contact surface, then release again and tighten with the prescribed pretension moment (Fig. ). This sequence prevents subsequent seizure at the contact surfaces (thread flanks, end contact surfaces). A set of mounting instructions is provided with every delivery for first-time users. Further copies can be provided on request.. Then tighten the lock screws and check the clamping screws again for the prescribed tightening torque. Tighten if necessary. Fig. 9
Assembly examples Fig. : The high load capacity and axial rigidity of the needle axial cylindrical bearing is reliably transmitted to the feed drive system via the mounted locknut. The excellent locking properties provided by the locknut are of major importance under dynamic stress. Fig. 12: Machine frame subjected to high levels of stress. The precise right-angled contact surface of the locknut guarantees that stress is exerted evenly on the bolt thread. There are no bending moments occurring. This is a particular advantage in applications involving dynamic stress.
Assembly examples Fig. 13: In the upper dimension range (from MSW 72.0), the required degree of axial pretension cannot be applied using the locknut s own pretension moment due to the size of the friction radii. Here, axial pretension is applied by integrated set screws. Fig. 1: Piston fixture with locknut. This application utilizes all the technical benefits of locknuts: Load capacity, axial rigidity and excellent locking properties.
No part of this publication may be reproduced in any form without our prior permission. The specifications and information provided in this catalogue are compiled and checked for correctness with the greatest of care. We are unable to accept liability for any errors or omissions which may have been overlooked. SPIETH-MASCHINENELEMENTE GmbH & Co KG Alleenstrasse 1 D-73730 Esslingen phone +9 (0)7 930730-0 fax +9 (0)7 930730-7 web: www.spieth-maschinenelemente.de email: info@spieth-maschinenelemente.de SN 0.03 e 005/0000/005