Disclosure to Promote the Right To Information

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1 इ टरन ट म नक Disclosure to Promote the Right To nformation Whereas the Parliament of ndia has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of ndian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. ज न1 क अ+धक र, ज 1 क अ+धक र Mazdoor Kisan Shakti Sangathan The Right to nformation, The Right to Live प0र 1 क छ ड न' 5 तरफ Jawaharlal Nehru Step Out From the Old to the New S (2000): Ball Screws, Part 3: Acceptance Conditions and Acceptance Tests [PGD 2: Machine Tool Elements and Holding Devices]! न $ एक न' भ रत क +नम-ण Satyanarayan Gangaram Pitroda nvent a New ndia Using Knowledge! न एक ऐस खज न > ज कभ च0र य नहB ज सकत ह ह BhartṛhariNītiśatakam Knowledge is such a treasure which cannot be stolen

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4 S 14872(Part 3) :2000 SO : 1992 mt3@m?r fr-tfmfdltdmwr@-wt ndian Standard BALL SCREWS PART 3 ACCEPTANCE CONDTONS AND ACCEPTANCE TESTS CS BS 2000 BUREAU OF NDAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELH September 2000 Price Group 9

5 Machine Tool Elements and Holding Devices Sectional Committee, BP 02 NATONAL FOREWORD This ndian Standard (Part 3) which is identical with SO :1992 Ball screws Part 3 : Acceptance conditions and acceptance tests issued by the nternational Organization for Standardization (SO) was adopted by the Bureau of ndian Standards on the recommendation of the Machine Tool Elements and Holding Devices Sectional Committee and approval of the Basic and Production Engineering Division Council. This standard deals with ball screws used on machine tools and is being issued in the following parts: 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 Ball screw axial rigidity Part 5 Distribution of static and dynamic loads and operational life At the moment, only standards on Parts 1, 2 and 3 are being issued whereas standards in regard to Parts 4 and 5 will be issued as soon as the work on them is completed at the nternational level. The text of the SO Standard has been approved as suitable for publication as ndian Standard without deviations. Certain conventions are, however, not identical to those used in ndian Standards. Attention is particularly drawn to the following: a) Wherever the words nternational Standard appear referring to this standard, they should be read as ndian Standard. b) Comma (,) has been used as a decimal marker while in ndian Standards, the current practice is to use a point (.) as the decimal marker. n the adopted standard, reference appears to certain nternational Standards for which ndian Standards also exist. The corresponding ndian Standards which are to be substituted in their place are listed below along with their degree of equivalence for the editions indicated. /rrfernationa/ Standard Corresponding ndian Standard Degree of Equivalence SO 230-1:1986 Acceptance S 2063 : 1988 Acceptance code for dentical code for machine tools-part 1 : machine tools Geometric accuracy of Geometric accuracy of ma- machines operating under no-load or chines operating under no-load finishing conditions (first revision) or finishing conditions SO 286-2:1988 SO system of S 919 (Part 2) :1993 SO systems of lim- imits and fits Part 2: Tables its and fits : Part 2 Tables of standard of standard tolerance grades grades and limit deviations for holes and and limit deviations for holes and shafts (first revision) shafts do SO :1991 Ball screws S (Part 1) :2000 Ball screws do Part 1 : Vocabulary and desig- Part 1 Vocabulary and designation nation (Bi/ingua/ edition) For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with S 2:1960 Rules for rounding off numerical values (revised). The number of significant places retained in the rounded off \/alue should be the same as that of the specified value in this standard.

6 S 14872( Part3) :2000 SO :1992 ndian Standard BALL SCREWS PART 3 ACCEPTANCE CONDTONS AND ACCEPTANCE TESTS 1 Scope This part of SO W specifies the technical acceptance conditions for ball screws (see figure 1) and, in particular, the respective permissible deviations for the acceptance teats. NOTE The actual design need not necessarily correspond to that shown in figure 1. The respective tests required shall be agreed upon between the manufacturer and the user. 2 Normative references editions of the standards indicated below. Members of EC and SO maintain registers of currently valid nternational Standards. SO : 19M, Acceptance code for machine tools Part 1: Geometric accuracy of machines operating under no- oad or finishing conditions. SO -2:1988, SO system of limits and fits Pert 2: Tabks of standard tolerance grades and limit deviations for holes and shafts. SO :1991, Ball screws Pert 1: Vocabulary and designation. The following standards contain provisions which, through reference in this text, constitute provisions of thk part of SO At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of SO 3408 are encouraged to investigate the possibility of applying the most recent 3 Definitions For the purposes of this part of SO 34(M, the definitions given in SO apply.

7 S (Part 3):2000 1s : Test conditions and permissible deviations 4.1 Classification The tests are graded in five standard toleranca grades (see table 1) in conformance with SO 286-2:1888, table 1. Table 1 Standard tolerance grades Table 2 Travel deviation tests Type of ball screw Travel deviations per P T reference length Teat Travel compensation c for useful travel/u Specified by user C=o Tolerance on specified travel ep E1.1 El.2 Standard tolerance grade 1 Standard tolerance grade 3 Standard tolerance grade 5 Standard tolerance grade 7 Standard tolerance grade 10 u ncreasing requirements on accuracy and function Permissible travel variation v p within useful travel Permissible travel variation Vmp within 300 mm travel Permissible travel variation V2=Pwithin 2rr rad E2 E3 E3 E4 4.2 Geometrical tests Tolerances Tolerances on specified travel, ep, for the useful travel, lu (teats El.1 and El.2), are taken directly from SO 286-2:1988, table 1. Values of ep for useful travel, /u, of greater than or equal to 3150 mm were calculated by linear extrapolation (see tabie Al). Tolerances on travel variation, VUP, in micrometres, within the useful travel, /u, were evaluated using the following equations: 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 meaauring ball by touching the ball track of a non-rotating ball screw shaft. For the measuring intervals, see table A.2. The travel variation V2Z within 27r rad is determined over nine measurements (8 x 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. where Grade 1: VUP = 0,0045 ~u + 4,6 _ Grade 3: ~,up = O,m ~u + 9,2 Grade 5: VUP = 0,018 ~u +!8,4 iu is the geometrical mean, in millimetrea, of the extreme lengths of each step of measured travel given in table A. 1: iu = J~x / ~in Run-out tolerances and orientation tolerances were determined from experience Travel deviations Depending on the type of ball screw considered [Positioning (type P) or transport (type T) ball screw], the teats given in table 2 shall apply Evaluation of the measuring diagrams To evaluate the actual mean travel deviation within the usefui travel, one may use either a mathematical method, which is precise by its very nature, or a graphical method, which is simple and quick and is recommended as an approximstion method suitable for everyday evaluations. NOTE The travel variation, Vua, resulting from the mathematical method may not be the minimum travel variation. The graphical method gives the minimum travel variation Mathematical (least square] method The actual mean travel deviation, es, is given by the formula % =a+by with The basic measuring principle is illustrated in figure 2. 2

8 S 14872(Pati3):~ 1s :1992 and Graphical method [see figure$ 3a) and 3b)l The evaluation of the actual mean travel deviation from the travei deviation diagram is carried out as foiiowe: where ea is the actual mean travel deviation in relation to the spacified or nominal travel, as appropriate; y is the angle of rotation (specified or nominal travel, as appropriate); yi is the angle of rotation (specified or nominal travel, as appropriate) correapohding to the ith measuring point; ei is the travel deviation (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. a) draw the tangents to the actuai travel deviation curve et two or more upper peaks (11, 12,...) and repeat this procedure for the iower peaks (13,...). b) determine the largest respective deviations (el, e2, e3r... ) 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 peek line (1> parallel to 12in the example). The actual mean travel deviation, ea, is the centraiine between these paraliel lines (12and KJ. Tha band width within the useful travel, vu, is the distance between these parallel lines, e2, measured psraliei to the ordinate. 3

9 S 14872(Part3):~ 1s0 340B-3 :1992 Bal L Ball nut body Figure 1 Ball screw Angular measuring instrument Measuring slide (accuracv < 10 ) / Ball nut body 1~ L Ball screw shaft ~Measuring instrument Clamping devica of travel (e.g. chuck), drive (accuracy = 0,001 mm} Figure 2 Basic measuring principle

10 S 14872(Patt3) :2000 1s :1992 a? H 1~ - al Deviation, e=, related to tha specified trevel, /~. ti 1 b] Daviation, e~, related to tha nominal travel, /0 ḋ e NOTE For the excess travel, eaa table A.3. Figure 3- Determination of the actuel mean travel deviation, emor e~

11 S 14872( Part 3 ) :2000 SO : Acceptance tests 5.1 Travel deviation and variation Test Diagram Object Measuring instruments a) + * 1 u c.- o %.- > 43 f... deviation, Specified travel, s+ travel, lu Checking of mean travel e, for useful E1.1 b) a) for the specified travel, s See figure 2 b) for the nominal travel, /0 El.2 Checking of mean travel deviation, e, for useful travel, /u See figure 2 Nominal travel, /0 z,

12 S 14872( Part 3 ) :2000 SO :1992 Test instruction Permissible deviations Observations and remarks Positioning ball screws / Standard tolerance mm grade e== pm up to above and ep including ~m m w a) See figure 2 m m b) 600 1(X)O c shall be specified by user c= (M ek= ~m cuxt (XO LM Transport ball screws Standard tolerance grade See figure 2 eoa= vm VWP, see test E3

13 S 14872(Part 3):20fj0 1s :1992 Test Diagram Objact Measuring instruments Specified, s E2 ;hecking of travel variation,, within useful travel, /u Sss figure 2 L VUP

14 S 14872( Part 3): s : jgg2 Test instruction Permissible deviations Observations and remarks, Positioning ball screws U Stsndard toleranca grade mm O up to above and UP including pm m cm m Soo See figure 2 m lo(n) a = ~m rM 2oal rM WJ (X W 119 Transport ball screws Vua is the smallest distance, measured parallel to the ordinate, between two lines parallel to the mean travel that UP envelop the actual travel deviation not specified over the useful travel /u. L 9

15 S 14872(Part 3):2000 1s :1992 Test Diagram Objact Measuring instruments + 300mm specified, s (nominal, /0) travel x + E3 Actual travel daviation Checking of travel variation, VW, within 300 mm axial travel See figure 2 L v300p Specified, 1, (nominal, /.) travel E4 + n.2rtrad ~ c.- o.- ; \ 5 \. g 1- ~hecking of travel variation, /2=, within 2n rad See figure 2 w L 2TD? ma. 10

16 S 14872(Part 3):2000 1s :1992 Test instruction Permissible deviations Obsemations and remarks See figure 2 Vwa is the smallest distance, measured parallel to the ordinate, found when a template is moved along the actual travel deviatidrr and parallel to the mean travel, which contains the actual travel deviation over any 300 mm length along the useful travel. Positioning or transport ball screws Standard tolerance grade _7_J 10 Wop ~m [ Vmamax = ~m See figure 2 Positioning ball screws v2n~is tte 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 distance corresponding to one revolution, i.e. 2X rad along the useful travel. Standard tolerance grade _LLL..l.!!? Vznp pm v2namax pm

17 S (Part3) :2000 SO : Run-out and location tolerances Test Diagram Object Measuring instruments &.- E5 1 r (%.. : Measurement of radial run- & -- 4 H A AA 2do 11 * out, t5,of ball screw shaft outer diameter for ascertain- ing straightness related to AA per length s Dial gauge V-blocks and A * a : E ** Measurement of radial runout, t~, of beering diameter related to AA per length f E6 for length [6 < For length /6 > 1 to be valid Dial gauge V-blocks and 2d0 A 16 [6 tw < 4jp ~ H - Measurement of radial runout, t7,ofjournal diameter related to bearing diameter by determining the difference.4 E7 for 1, < Dial gauge V-blocks and For 1, > to be valid 7a < 7p ~ 17 i r

18 S 14872(Part3) :2000 1s :1992 Test instruction {Reference to test code Permissible deviations 1s0230-1: 1986) Positioning or transport bail screws lace ball screw on identical V-blocks Nominal diameter Standard tolerance )t points A and A. do grede mm lb, ;et dial gauge with measuring shoe at mm up to he distance f5 perpendicular to the t5p for /5 above and cylindrical surface. including ~m 6 12 &)?otate the ball screw slowly and ecord the changes in the dial gauge eading. Repeat the measurement at m ;pecified measuring intervals UOTES 11X Nominal diameter Optionally, measurement by supporting d. :he ball screw shaft at both centres may be up to and JSedby agreement. above including f5max P for /1 >415 pm? if /1 < 2/5, take the measurement at / (Clause ) la Observations and remarks t%= pm t5maxa= vm Positioning or transport ball screws Jlace the ball screw at points A Nominal diameter Standard tolerance md A on V-blocks. do grade mm 1 mm l 13_Lz_l o Wthe dial gauge at the distance [6 up to t% for perpendicular to the cylindrical above and t6a Diameter ;ljriace. including ~m pm?otate the ball screw slowly and ecord the dial gauge readings ~~~~~~~~~~~~ w m. ~~~~~~~~~~~~ m lm.. (Clause ) < Place the ball screw at points A Positioning or transport ball screws and A on V-blocks. Nominal diameter Standard tolerance do grade Put dial gauges at the distance 17 per- mm O mm pendicular to the cylindrical surface. up to t7pfor above and t7a Diameter Rotate the ball screw slowly and including pm ~m record the difference in dial gauge , readings (Clause )

19 S 14872(Patt3):2~ 1s :

20 S 14872( Part 3 ) :2000 SO :1992 Test instruction (Reference to test code Permissible deviations 1s0230-1: 1986) Place ball screw at points A and A on V-blocks. Observations and remarks Positioning or trensport bell screws Secure the ball screw shaft in the axial direction against movement (e.g. by Nominal diameter Standard tolerance placing a ball between the centres of do grade the ball screw shaft and the mounting mm 1 3 surface) up to t~ above and t& Place dial gauges perpendicular to the Diameter including pm pm end face of the journal and to the 6 cylindrical surface of the correspond ing diameter m Rotate the ball screw and record the + dial gauge readings. (Clause 5.632) System preioaded. Place ball screw on V-blocks at points A and A. Secure the ball screw shaft in the axial direction against movement (e.g. by placing a ball between the centres of the ball screw shaft and the mounting surface). Place the dial gauge perpendicular to the flange face at the outer rim of inspection diameter D2. Secure the ball nut against rotation on the ball screw shaft. above Positioning or trensport bell screws Flange diametar D2 16 Standard tolerance grade mm up to and including t9p pm t~mx= pm Rotate the ball screw shaft and record the dial gauge readings. (Clause 5.632) System preloaded. Place ball screw on Positioning or transpoti ball screws V-blocks at points A and A. Ball nut body Place the dial gauge perpendicular to outer Standard tolarance diametar grada the cylindrical surface of ball nut D, location diameter D,. mm Secure the ball screw shaft. Rotate the ball nut body slowly. Record the dial gauge readings. above 16 up to and including (Clause ) WO flop pm loarnax = ~m 15

21 S 14872( Part3) :2000 SO :1992 Test Diagram Object Measuring instruments Deviation of parallelism, tll, El 1 of rectangular ball nut related to AA (for preloaded Dial gauge V-blocks and ball nuts only)

22 S 14872(Part3) :2000 SO :1992 Test instruction (Reference to test code 1s : 1986) Permissible deviations Observations and remarks System preloaded. Place ball screw on V-blocks at points Aand A. Place the dial gauge perpendicular to the inspection surface and probe along the specified inspection length 1. Positioning or transport ball screws Standard tolerance grade ~llp for each 100 mm (cumulative) fllamx= ~m Record the dial gauge readings. (Clause )

23 S 14872( Part3) :2000 iso : Functionaltests Test Diagrem Object Measuring instruments Forceindicator Efi 1 TV = F. without end seals 3 TP = Ft.! with end seals a~ l-?? Meeswement of tolerance Test bench with on dynamic preloaded drag recorder for force torque, A TP value measured!? % u ~.. -.!.0, 0,,, & [n = ball nut length lu - 1 [U - 1 r= Travel ~

24 S 14872(Part3) :2000 1S :1992 Test instruction Permissible deviations Observations and remarks Positioning or transport ball straws Nm Standard tolarance grade up to For/u/rfo< 40; /u < 40(H)mm above and A Tw including % of T@ 0,2 0, ,4 0, Without end seals 0, ; = nl 1 2, ystem preloaded (with or without 2,5 6, nd seals). 6, or the recording of the radial preload T@ orce, couple the ball nut body to a Nm For/u/do< 60; /u < 4000mm Mdcell at the d!stance / from the axis A Tpp up to f rotation. above and 94. of TN including F = N Tp = Nm ATPa=* Q Nm % of T@ ake recordings at a rotational speed 0,2 0,4 ~ )f lk min 1 in both directions of 0,4 0, otation. 0, : Whh end seals or lubrication, use a lubricant of SO 1 2, m- hscosity grade 100.1, 2,5 6, i- 35 6, T@ Ft = N Tw = Nm ATti =i nm Nm For/U >4000mm e *... % of T@ up to A TPP above and % of T@ including 0,6 not specified 0, , ,5 6, , ) Other rotational speeds, lubricants and measuring instruments may be used by agreement between the user and the msnufscturar. 19

25 S 14872( Patt 3 ) :2000 SO :1992 Test Diagram Object Measuring instruments rotation Axislly fixed - Measurement rigidity, 1? u of axial Dial gauges and load call k u m E13 ; lfpr - F / 1 t0,5fpc T -F ~ Deformation, Al -lfp, - All - -

26 S 14872( Part 3 ) :2000 SO :1992 Test instruction Observations and remarks Fix preloaded ball nut axially in both directions and secure ball screw shaft against rotation. Place dial gauge supports on the ball screw shaft and touch the measuring stylus against the face of the ball nut body, as near as possible and as parallel as possible to the ball screw shaft axis. Apply axial loads F, = 0,5FPr or F2 = 2Fpr to the ball screw shaft in tension and in compression. Fpr is the preload and Al, or Alp are the elastic deformations (reversal range) caus ed by the axial test loads *F, or * F2 respectively. Rigidity in the range + F, : 2F, F R ~=$ nul = 1 1 Rigidity in the range and Flto Fz: + F, to + F2 2(F2 F,) 3Fpr Rnu2 =. Alz All Alz Ail Fpr = N F, = N F2 = N All =., ~m A12,,...~m R nil=.... N/pm Rnu2= N/pm Other test loads F may be used by agreement between the user and the manufacturer. * 21

27 S ( Part 3 ) :2000 SO :1992 Annex A (normative) Complementary tables Table A.1 Tolerance values on specified travel, ep, for a band width per 300 mm (v~m) and for a mean travel deviation, e, and for the standard tolerance grades according to SO 288-2:1988 above Measurad travel Standard tolerance grada mm J+3L.-~---.l up to and Tolerance on specified travel, ep including ~m.-..: o m m leqo * * CQ 5000 g,) 76*,a*) 320 ) ~, 92 ) 170*) 39 * These values were calculated by linear extrapolation from the T values in accordance with SO for sizes above 500 mm and less than or equal to 3150 mm. ~1~ 105 Table A.2 Minimum number of measurements over 300 mm (maasuring intervals) Lead P~ mm L Specified tolerance grade E_bd L..:o. Minimum numbar of measurements Table A.3 Maximum excess travel Dimensions in millimetres Laad P~ 2, Maximum excess,0 travel /e ~ax

28 Bureau of ndian Standards BS is a statutory institution established under the Bureau of ndian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright BS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications), BS. Review of ndia Standards Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes arc needed; if the review indicates that changes are needed, it is taken up for revision. Users of ndian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of BS Catalogue and Standards: Monthly Additions. This ndian Standard has been developed from DOC : No. BP/PE 02 (210). Amendments ssued Since Publication Amend No. Date of ssue Text Affected Headquarters : BUREAU OF NDAN STANDARDS Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi Telegrams : Manaksanstha Telephones : , , (Common to all offices) Regional Offices : Telephone Central Eastern Manak Bhavan, 9 Bahadur Shah Zafar Marg NEW DELH { /14 C.. T. Scheme V M, V.. P. Road, Kankurgachi , CALCUTTA { , Northern SCO , Sector 34-A, CHANDGARH { Southern C.. T. Campus, V Cross Road, CHENNA { , , Western Branches Manakalaya, E9 MDC, Marol, Andheri (East) , MUMBA { , AHMADABAD. BANGALORE. BHOPAL. BHUBANESHWAR. COMBATORE. FARDABAD. GHAZABAD. GUWAHAT. HYDERABAD. JAPUR. KANPUR. LUCKNOW. NAGPUR. PATNA. PUNE. RAJKOT. THRUVANANTHAPURAM. Printed at PRNTOGRAPH, New Ddhi