1、BRITISH STANDARD BS6101-2: 1991 Machine tool ball screws Part2: Specification for accuracy, including geometrical testsBS6101-2:1991 This British Standard, having been prepared under the directionof the Machine, Engineers and Hand Tools Standards Policy Committee, waspublished under the authorityof
2、the StandardsBoardand comesintoeffect on 30April1991 BSI11-1999 First published December1982 Second edition April1991 The following BSI references relate to the work on this standard: Committee reference MTE/1 Draft for comment88/70227 DC ISBN 0 580 18115 4 Committees responsible for this British St
3、andard The preparation of this British Standard was entrusted by the Machine, Engineers and Hand Tools Standards Policy Committee (MTE/-) to Technical Committee MTE/1, upon which the following bodies-were represented: Advanced Manufacturing Technology Research Institute Cranfield Institute of Techno
4、logy Department of Trade and Industry Mechanical Engineering and Manufacturing Technology Division (Mmt) Federation of British Engineers Tool Manufacturers Health and Safety Executive Ministry of Defence Society of British Aerospace Companies Individual experts Amendments issued since publication Am
5、d. No. Date CommentsBS6101-2:1991 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Application of test methods 1 4 Abbreviations 1 5 Accuracy grades 1 Appendix A Complementary tables 14 Appendix B Determination of concentricity of balltrac
6、k with screwshaft 14 Figure 1 Ball screw 3 Figure 2 Basic measuring principle 3 Figure 3 Determination of the actual mean travel deviation e saor e oa 4 Figure 4 Checking ball track concentricity 14 Table 1 Standard tolerance grades 1 Table 2 Travel deviation tests 2 Table 3 Geometrical tests for ma
7、chine tool ball screws 5 Table 4 Minimum number of measurements over300mm(measuringintervals) 14 Table 5 Maximum excess travel 14 Publication(s) referred to Inside back coverBS6101-2:1991 ii BSI 11-1999 Foreword This Part of BS6101 has been prepared under the direction of the Machine, Engineers and
8、Hand Tools Standards Policy Committee in response to requests from machine tool manufacturers who use ball screws in their machines. This edition supersedes BS6101-2:1982 which is withdrawn. This Part of BS6101 is based on, but is not identical to, ISO/DIS3408-3 prepared by the International Organiz
9、ation for Standardization (ISO). It is limited to ball screws of up to2500mm travel which suits the UK home and export requirements. DIS3408 goes beyond that and up to6300mm travel. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards
10、are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to14, an inside back cover and a back cover. This standard
11、has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6101-2:1991 BSI 11-1999 1 1 Scope This Part of this British Standard specifies requirements for accuracy and describes geometrical tests for re-ci
12、rculating ball screws for use in machine tool applications. This standard is applicable to re-circulating ball screw assemblies having the shafts and nuts manufactured from hardened steel. It deals only with the verification of accuracy of ball screw assemblies before mounting in the machine tool. I
13、t does not apply to testing the running of the machine tool. Complementary tables are given in Appendix A. Appendix B describes a method of measuring the error in the balltrack. NOTEThe titles of the publications referred to in this standard are given on the inside back cover. 2 Definitions for the
14、purposes of this Part of BS6101, the definitions given in BS6101-3 apply NOTESeeFigure 1. 3 Application of test methods 3.1 The tests in Table 3 may be applied in any order that is practicable and that makes for ease of mounting of instruments or gauging. The sequence in which the geometrical tests
15、are listed in Table 3 is not intended to impose the practical order in which the tests are to be done. 3.2 For tests G5 to G11, the shaft shall be set parallel to the surface on which the tests are carried out. For the purposes of these tests, it is assumed that the balltrack has been checked to pro
16、ve its concentricity with the outside diameter of the screwed portion of the shaft, therefore the use of this outside diameter for reference purposes is acceptable. If the balltrack is found not to be concentric, then the error shall be taken into account when measuring the permissible deviation. (S
17、eeAppendix B.) 4 Abbreviations For the purposes of this standard, the use of “per” in column4 of Table 1 has a specific meaning as follows. 5 Accuracy grades 5.1 General The tests are graded in five standard tolerance grades (seeTable 1) in compliance with BS4500-1 and Table 2 of ISO/R1938:1971. The
18、 value v 300(testG3) of the travel variation, v, within300mm travel served as a basis for the classification. Table 1 Standard tolerance grades 5.2 Geometrical tests 5.2.1 Tolerances Tolerances on specified travel, e p , for the useful travel, l u(tests G1.1 and G1.2), are taken directly from Tables
19、2 and 2A of ISO/R1938:1971. Tolerances on travel variation, v up , in micrometres, within the useful travel, l u , were evaluated using the following equations: Grade IT1: v up =0.0045 Grade IT3: v up =0.009 Grade IT5: v up =0.018 whereis the geometrical mean, in millimetres, of the extreme lengths
20、of each step: =(l u max l u min ) Run-out tolerances and orientation tolerances were determined from experience. 5.2.2 Travel deviations 5.2.2.1 General Depending on the type of ball screw considered (positioning or transport ball screw) the tests given in Table 2 shall apply. The basic measuring pr
21、inciple is illustrated in Figure 2. Tests and tolerances refer to the ball nut body displacement 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, seeTab
22、le 4. The travel variation v 2 ;within2; 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 test has been the subject of a special agreement. - per - This type of expressio
23、n applies to deviations of straightness and parallelism, and is used to recommend a measurement length, but in this case the proportionality rule comes into operation if the measurement length differs from that indicated. Standard tolerance grade IT1 IT3 IT5 IT7 IT10 Increasing requirements on accur
24、acy and function l u 4.6 + l u 9.2 + l u 18.4 + l u l uBS6101-2:1991 2 BSI 11-1999 Table 2 Travel deviation tests 5.2.2.2 Evaluation of the measuring diagrams 5.2.2.2.1 Choice of methods To determine the actual mean travel deviation within the useful travel, one may use either a mathematical method,
25、 which is precise by its very nature, or a graphical method, which is simple and quick and is recommended as an approximation method suitable for every day evaluations. 5.2.2.2.2 Mathematical method The actual mean travel deviation, e a , is given by the formula e a = a + b where e a is the actual m
26、ean 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; e i is the travel deviation
27、(or travel) in relation to the specified or nominal travel for the angle of rotation (or travel) corresponding to the ith measuring point; n is the number of measuring points. 5.2.2.2.3 Graphical method see Figure3(a) and Figure3(b) The determination of the actual mean travel deviation from the trav
28、el deviation diagram is carried out as follows: a) draw one or several tangents to the actual travel deviation curve at at least two upper peaks (l 1 , l 2 , . . . ) and repeat this procedure for the lower peaks (l 3 , . . . ); b) determine the respective largest deviations (e 1 , e 2 , e 3 , . . .
29、) parallel to the ordinate, and select from these the smallest deviation (e 2in the example); c) draw a straight line through this point of minimum deviation that is parallel to the corresponding peak line (l 2parallel to l 2in the example). The actual mean travel deviation, e a , is the centreline
30、between these parallel lines (l 2and l 2 ) and the band width within the useful travel, v ua , is the distance between these parallel lines, e 2 , measured parallel to the ordinate. Travel deviations per reference length Type of ball screw Positioning Transport Test Travel compensation c for useful
31、travel l u Specified by user c=0 Tolerance on specified travel e p G11 G12 Permissible travel variation v upwithin useful travel G2 Permissible travel variation v 300pwithin300mm travel G3 G3 Permissible travel variation v 2;pwithin2; rad G4 BS6101-2:1991 BSI 11-1999 3 Figure 1 Ball screw Figure 2 B
32、asic measuring principleBS6101-2:1991 4 BSI 11-1999 Figure 3 Determination of the actual mean travel deviation e saor e oaBS 6101-2:1991 BSI 11-1999 5 Table 3 Geometrical tests for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test c
33、ode BS3800 G1.1 Checking of mean travel deviation, e, for useful travel, l u a) for the nominal travel, l o b) for the specified travel l s Positioning ball screws c shall be specified by user l u(inmm) Standard tolerance grade IT1 IT3 IT5 IT7 IT10 above up to and including e p(in4m) 0 315 6 12 23 3
34、15 400 7 13 25 400 500 8 15 27 500 630 9 16 30 630 800 10 18 35 800 1000 11 21 40 1000 1250 13 24 46 1250 1600 15 29 54 1600 2000 18 35 65 2000 2500 22 41 77 G1.2 Checking of mean travel deviation, e, for useful travel, l u Transport ball screws Standard tolerance grade IT1 IT3 IT5 IT7 IT10 c =0 e p
35、 = v 300p , see test G3 l u 300 -v 300BS 6101-2:1991 6 BSI 11-1999Table 3 Geometrical tests for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test code BS3800 G2 Checking of travel variation, v, within useful travel, l u NOTEv uais t
36、he 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 l u Positioning ball screws l u (inmm) Standard tolerance grade IT1 IT3 IT5 IT7 IT10 above up to and including v up (in4m) 0 315 6 12
37、 23 315 400 6 12 25 400 500 7 13 26 500 630 7 14 29 630 800 8 16 31 800 1000 9 17 33 1000 1250 10 19 39 1250 1600 11 22 44 1600 2000 13 25 51 2000 2500 15 29 59 Transport ball screws Standard tolerance grade IT1 IT3 IT5 IT7 IT10 v up not specifiedBS 6101-2:1991 BSI 11-1999 7Table 3 Geometrical tests
38、 for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test code BS3800 G3 Checking of travel variation, v 300 , within300mm axial travel Positioning or transport ball screws v 300ais the smallest distance (measured parallel to the ordin
39、ate), found when a template is moved along the actual travel deviation and parallel to the mean travel, which contains the actual travel deviation over any300mm length along the useful travel Standard tolerance grade IT1 IT3 IT5 IT7 IT10 v 300p (in4m) 6 12 23 52 210 G4 Checking of travel variation,
40、v 2; , within2; rad Positioning or transport ball screws v 2 ;ais the smallest distance (measured parallel to the ordinate), found when a template is moved along the actual travel deviation and parallel to the mean travel, which contains the actual travel deviation over any distance2; along the usef
41、ul travel Standard tolerance grade IT1 IT3 IT5 IT7 IT10 v 2;p(in4m) 4 6 8 BS 6101-2:1991 8 BSI 11-1999Table 3 Geometrical tests for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test code BS3800 G5 Checking of radial run-out, t 5 , o
42、f ball screw shaft outer diameter for ascertaining straightness related to AA per length l 5 Positioning or transport ball screws 5.612.2 Nominal diameter l 5(inmm) Standard tolerance grade d o(inmm) IT1 IT3 IT5 IT7 IT10 NOTEIf l 1 2l 5 , take the measurement at l 1 /2 above up to and including t 5p
43、forl 5(in4m) 6 12 80 12 25 160 25 50 315 20 25 32 40 80 50 100 630 100 200 1250 Nominal diameter, d o (inmm) t 5maxfor l 1(in4m) above up to and including 40 40 50 64 80 160 40 60 60 75 96 120 240 60 80 100 125 160 200 400 80 100 160 200 256 320 640BS 6101-2:1991 BSI 11-1999 9Table 3 Geometrical tes
44、ts for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test code BS3800 G6 Checking of radial run-out, t 6 , of bearing diameter related to AA per length l forlength l 6 k l Forlength l 6 l to be valid Positioning or transport ball scr
45、ews 5.612.2 Nominal diameter l (inmm) Standard tolerance grade d 0(inmm) IT1 IT3 IT5 IT7 IT10 above up to and including t 6pfor l (in4m) 6 20 80 10 12 20 40 63 20 50 125 12 16 25 50 80 50 125 200 16 20 32 63 100 125 200 315 25 40 80 125 G7 Checking of radial run-out, t 7 , of journal diameter relate
46、d to bearing diameter by determining the difference% for l 7 k l For l 7 l to be valid Positioning or transport ball screws 5.612.2 Nominal diameter, l (inmm) Standard tolerance grade d 0(inmm) IT1 IT3 IT5 IT7 IT10 above up to and including t 7pfor l (in4m) 6 20 80 5 6 8 12 16 20 50 125 6 8 10 16 20
47、 50 125 200 8 10 12 20 25 125 200 315 12 16 25 32 t 6a t 6p l 6 l - t 7a t 7p l 7 l - BS 6101-2:1991 10 BSI 11-1999Table 3 Geometrical tests for machine tool ball screws 1 2 3 4 5 Test Diagram Object Permissible deviations Observations and references to the test code BS3800 G8 Checking of axial run-
48、out, t 8 , of shaft (bearing) faces related to AA Positioning or transport ball screws 5.632 Nominal diameter, Standard tolerance grade d o(inmm) IT1 IT3 IT5 IT7 IT10 above up to and including t 8p(in4m) 6 63 3 4 5 6 10 63 125 4 5 6 8 12 125 200 6 8 10 16 G9 Checking of radial run-out, t 9 , of ball
49、 nut location face related to AA (for preloaded ball nuts only) Positioning or transport ball screws 5.632 Flange diameter, Standard tolerance grade D 2(inmm) IT1 IT3 IT5 IT7 IT10 above up to and including t 9p(in4m) 16 32 10 12 16 20 32 63 12 16 20 25 63 125 16 20 25 32 125 250 20 25 32 40 250 500 32 40 50 BS 6101-2:1991 BSI 11-1999 11Table 3 Geometrical tests for
