BS-ISO-3408-3-2006.pdf

BRITISH STANDARD BS ISO 3408-3:2006 Ball screws Part 3: Acceptance conditions and acceptance tests ICS 25.060.99 ? Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 3408-3:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2006 © BSI 2006 ISBN 0 580 48900 0 National foreword This British Standard reproduces verbatim ISO 3408-3:2006 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee MTE/1, Machine tools, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 25 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 3408-3:2006(E) INTERNATIONAL STANDARD ISO 3408-3 Second edition 2006-06-15 Ball screws Part 3: Acceptance conditions and acceptance tests Vis à billes Partie 3: Conditions et essais de réception BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Test conditions and permissible deviations 2 4.1 Classification. 2 4.2 Geometrical tests 2 5 Acceptance tests 6 5.1 General. 6 5.2 Travel deviation and variation. 7 5.3 Run-out and location tolerances. 12 5.4 Functional tests 22 Annex A (normative) Complementary tables 24 BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 3408-3 was prepared by Technical Committee ISO/TC 39, Machine tools. This second edition cancels and replaces the first edition (ISO 3408-3:1992), which has been technically revised. ISO 3408 consists of the following parts, under the general title Ball screws: Part 1: Vocabulary and designation Part 2: Nominal diameters and nominal leads Metric series Part 3: Acceptance conditions and acceptance tests Part 4: Static axial rigidity Part 5: Static and dynamic axial load ratings and operational lifetime BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Ball screws Part 3: Acceptance conditions and acceptance tests 1 Scope This part of ISO 3408 specifies the technical acceptance conditions for ball screws (see Figure 1) and, in particular, the respective permissible deviations for the acceptance tests. NOTE The actual design need not necessarily correspond to that shown in Figure 1. The respective tests required will be agreed upon between the manufacturer and user. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 230-1:1996, Test code for machine tools Part 1: Geometric accuracy of machines operating under no- load or finishing conditions ISO 286-2:1988, ISO system of limits and fits Part 2: Tables of standard tolerance grades and limit deviations for holes and shafts ISO 3408-1:2006, Ball screws Part 1: Vocabulary and designation 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 3408-1 apply. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 4 Test conditions and permissible deviations 4.1 Classification The tests are graded in six standard tolerance grades (see Table 1) in conformance with ISO 286-2:1988, Table 1. Table 1 Standard tolerance grades Standard tolerance grade 0 Standard tolerance grade 1 Standard tolerance grade 3 Standard tolerance grade 5 Standard tolerance grade 7 Standard tolerance grade 10 Increasing requirements on accuracy and function 4.2 Geometrical tests 4.2.1 Tolerances Tolerances on specified travel, ep, for the useful travel, lu (tests E 1.1 and E 1.2), are taken directly from ISO 286-2:1988, Table 1. Values of ep for useful travel, lu, of greater than or equal to 3 150 mm were calculated be linear extrapolation (see Table A.1). Tolerances on travel variation, vup, in micrometres, within useful travel lu were evaluated using the following equations: Grade 0: vup = 0,0035 u l + 2,4 Grade 1: vup = 0,0045 u l + 4,6 Grade 3: vup = 0,009 u l + 9,2 Grade 5: vup = 0,018 u l + 18,4 where u l is the geometrical mean, in millimetres, of the extreme lengths of each step of measured travel given in Table A.1: uu maxu min lll= Run-out tolerance and orientation tolerances were determined from experience. 4.2.2 Evaluation of the measuring diagrams 4.2.2.1 General To evaluate the actual mean travel deviation within the useful travel, either a mathematical method precise by its nature or a graphical method simple and quick and recommended as an approximation method suitable for everyday evaluation may be used. NOTE The travel variation, vua, resulting from the mathematical method may not be the minimum travel variation. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 The graphical method gives the minimum travel variation. 4.2.2.2 Mathematical (least square) method The actual mean travel deviation, ea, is given by the formula a eab=+ with 2 2 iiiii iii ee a n = and 2 iiii iii nee b n = where ea is the actual mean travel deviation in relation to the specified or nominal travel, as appropriate; is the angle of rotation (specified or nominal travel, as appropriate); i is the angle of rotation (specified or nominal travel, as appropriate) corresponding to the ith measuring point; ei is the travel deviation (or travel) in relation to the specified or nominal travel for the angel of rotation (or travel) corresponding to the ith measuring point; n is the number of measuring points. 4.2.2.3 Graphical method see Figure 3 a) and b) The evaluation of the actual mean travel deviation from the travel deviation diagram is carried out as follows: a) draw the tangents to the actual travel deviation curve at two ore more upper peaks (l1, l2, .) and repeat this procedure for the lower peaks (l3, .); b) determine the largest respective deviations (e1, e2, e3, .) parallel to the ordinate, and select from these the smallest deviation (e2 in the example); c) draw a straight line through this point of minimum deviation that is parallel to the corresponding peak line (l2 parallel to l2 in the example). The actual mean travel deviation, ea, is the centreline between these parallel lines (l2 and l2). The bandwidth within the useful travel, vua, is the distance between these parallel lines, e2, measured parallel to the ordinate. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 Key 1 ball screw shaft 2 ball 3 ball nut Figure 1 Ball screw Key 1 ball nut 2 angular measuring instrument (permissible error = 10”) 3 measuring slide 4 travel measuring instrument (permissible error = 1 µm) 5 clamping device (e.g. chuck), drive 6 ball screw shaft Figure 2 Basic measuring principle BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 a) Deviation esa related to specified travel ls b) Deviation e0a related to nominal travel l0 NOTE For the excess travel, see Table A.3. a Travel deviation. Figure 3 Determination of the actual mean travel deviation, esa or e0a BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 6 5 Acceptance tests 5.1 General The typical tolerance grades for positioning and transport ball screws are given in Table 2. Table 2 Typical tolerance grades for positioning and transport ball screws Type of ball screw Standard tolerance grade Positioning 0 1 3 5 Transport 0 1 3 5 7 10 The test according to Table 3 shall apply, depending on the type of ball screw considered positioning (type P) or transport (type T) ball screw. The basic measuring principle is illustrated in Figure 2. Table 3 Travel deviation tests Type of ball screw Positioning Transport Travel deviations per reference length Test Travel compensation c for useful travel lu Specified by user C = 0 Tolerance on specified travel ep E 1.1 E 1.2 Permissible travel variation vup within useful travel E 2 Permissible travel variation v300p within 300 mm travel E 3 E 3 Permissible travel variation v2p within 2 rad E 4 Tests and tolerances to the ball nut displacement are relative to the ball screw shaft. A pitch-to-pitch measurement may be carried out using a measuring ball by touching the ball track of a non- rotating ball screw shaft. For the measuring intervals, see Table A.2. The travel variation v2 within 2 rad is determined over nine measurements (8 × 45°) per revolution, or continuously within one thread (at the start, in the middle and at the end of useful travel), provided that this has been the subject of special agreement. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 7 5.2 Travel deviation and variation Object: Positioning ball screw E 1.1 Checking of the mean travel deviations, esa and e0a, within the useful travel, lu: a) for the specified travel, ls; b) for the nominal travel, l0. Diagram a Actual travel deviation. Permissible deviations Useful travel lu mm Tolerance on specified travel ep µm Standard tolerance grade u 0 1 3 5 7 10 0 315 4 6 12 23 315 400 5 7 13 25 400 500 6 8 15 27 500 630 6 9 16 32 630 800 7 10 18 36 800 1 000 8 11 21 40 1 000 1 250 9 13 24 47 1 250 1 600 11 15 29 55 1 600 2 000 18 35 65 2 000 2 500 22 41 78 2 500 3 150 26 50 96 3 150 4 000 32 62 115 4 000 5 000 76 140 5 000 6 300 170 Observations and remarks a) esa = _ µm b) The travel compensation c shall be specified by the user c = _ e0a = _ µm Measuring instruments See Figure 2. Test instructions See Figure 2. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 8 Object: Transport ball screw E 1.2 Checking of the mean travel deviation e0a, within the useful travel, lu: Diagram a Actual travel deviation. Permissible deviations Tolerance on specified travel ep µm Standard tolerance grade 0 1 3 5 7 10 u p300p 300 l ev= ± Observations and remarks e0a = _ µm Measuring instruments See Figure 2. Test instructions See Figure 2. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 9 Object: Positioning ball screw E 2 Checking of the travel variation vu within the useful travel, lu: Diagram a Actual travel deviation. Permissible deviations Useful travel lu mm Travel variation vup µm Standard tolerance grade u 0 1 3 5 7 10 0 315 3,5 6 12 23 315 400 3,5 6 12 25 400 500 4 7 13 26 500 630 4 7 14 29 630 800 5 8 16 31 800 1 000 6 9 17 34 1 000 1 250 6 10 19 39 1 250 1 600 7 11 22 44 1 600 2 000 13 25 51 2 000 2 500 15 29 59 2 500 3 150 17 34 69 3 150 4 000 21 41 82 4 000 5 000 49 99 5 000 6 300 119 Observations and remarks vua = _ µm Measuring instruments See Figure 2. Test instructions See Figure 2. vua is the smallest distance, measured parallel to the ordinate, between two lines parallel to the mean travel that envelop the actual travel deviation over the useful travel lu. BS ISO 3408-3:2006 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 08:50:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 10 Object: Positioning or transport ball screw E 3 Checking of the travel variation v300 within an axial travel of 300 mm: Diagram a Actual travel deviation. Permissible deviations Standard tolerance grade 0 1 3 5 7 10 v300p µm 3,5 6 12 23 52a 210a a Only for transport ball screws. Observations and remarks v300a max = _ µm Measuring instru