《BS-7882-2008.pdf》由会员分享,可在线阅读,更多相关《BS-7882-2008.pdf(30页珍藏版)》请在三一文库上搜索。
1、BS 7882:2008 Method for calibration and classification of torque measuring devices ICS 17.100 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontr
2、olled Copy, (c) BSI Publishing and copyright information The BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2008 ISBN 978 0 580 55351 6 The following BSI references relate to the work on this standard: Committee reference ISE/NFE/4 Draft for comment
3、07/30133498 DC Publication history First published May 1997 Second edition, January 2008 Amendments issued since publication Amd. no.DateText affected BS 7882:2008 Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BS
4、I BSI 2008i BS 7882:2008 Contents Foreword ii 1Scope 1 2Terms, definitions, abbreviations and symbols 1 3Preparation for calibration 3 4Calibration procedure 7 5Calculation of results 8 6Classification of torque measuring devices 11 7Calibration certificate 13 Annexes Annex A (informative) Orientati
5、on diagrams 14 Annex B (informative) Method example of determining uncertainty of the calibration results of the torque measuring device 16 Bibliography 25 List of figures Figure A.1 Example of preloading and calibration sequences for a torque measuring device with round shaft drives, six increasing
6、 and decreasing torques, classes 0.05 to 5.0 14 Figure A.2 Example of preloading and calibration sequences for a torque measuring device with round shaft drives, six increasing torques only, classes 0.05 to 5.0 14 Figure A.3 Example of preloading and calibration sequences for a torque measuring devi
7、ce with square drives, six increasing and decreasing torques, classes 0.05 to 5.0 14 Figure A.4 Example of preloading and calibration sequences for a torque measuring device with square drives, six increasing torques only, classes 0.05 to 5.0 15 Figure A.5 Example of preloading and calibration seque
8、nces for a torque measuring device, six increasing and decreasing torques, classes 0.2 to 5.0. 15 Figure A.6 Example of preloading and calibration sequences for a torque measuring device, six increasing torques only, classes 0.2 to 5.0 15 Figure B.1 Worked example in torque units: 100 Nm torque meas
9、uring device clockwise torque, increasing series only 19 Figure B.2 Uncertainties calculated in accordance with B.3 20 Figure B.3 Worked example in mV/V: 2 kNm torque measuring device clockwise torque, increasing and decreasing series 22 Figure B.4 Uncertainties calculated in accordance with B.4 24
10、List of tables Table 1 Uncertainty of calibration torques 3 Table 2 Criteria for classification of torque measuring devices 12 Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 25 and a back cover. Licensed Copy: London South Bank University, L
11、ondon South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BS 7882:2008 ii BSI 2008 Foreword This British Standard is published by BSI and came into effect on 31 January 2008. It was prepared by Technical Committee ISE/NFE/4, Torque measurement and testing. A list of
12、 organizations represented on this committee can be obtained on request to its secretary. Supersession BS 7882:2008 supersedes BS 7882:1997, which is withdrawn. Presentational conventions The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in se
13、ntences in which the principal auxiliary verb is “shall”. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element. Contractual and legal considerations This publication does not purport to include all the necessary pro
14、visions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BSI 20
15、081 BS 7882:2008 1 Scope This British Standard specifies requirements for the calibration and classification of torque measuring devices, including those used for the calibration of hand torque tools to BS EN ISO 6789. It describes the method of calibration, calculation of calibration results and th
16、e classification of the torque measuring device in a static mode. The information to be given on the certificate of calibration is also listed. 2 Terms, definitions, abbreviations and symbols For the purposes of this British Standard, the following terms, definitions, abbreviations and symbols apply
17、. NOTEWhere applicable, this British Standard has been prepared using PD 6461-1. 2.1calibration torque torque with traceability derived from national standards of mass, length and time, and of specified uncertainty of measurement, which can be applied to the torque measuring device 2.2deflection d a
18、lgebraic difference between the indicator reading prior to the application of a torque and the indicator reading for each applied torque in a given measurement series NOTEThe deflection may be derived from either digital data output or visual data output. 2.3data acquisition system electronic module
19、 that has the ability to transfer, store, amplify and filter signals from a torque measuring device NOTEWhere analogue signals are acquired by the torque measuring device, and these are converted into a digital data stream using an analogue to digital converter, the stream of data may be digitally f
20、iltered, re-sampled and stored, or logged ready for analysis. 2.4loading direction direction of applied torque, either clockwise or anti-clockwise about the axis of rotation, when viewed from the end of the torque measuring device to which the calibration torque is applied 2.5lower limit of calibrat
21、ion Tmin lower value of torque at which a torque measuring device of a given class can be calibrated 2.6reference standard equipment used to generate or to measure the reference torque applied to the torque measuring device that is being calibrated NOTETorques may be generated by a power source moni
22、tored by the reference standard. Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BS 7882:2008 2 BSI 2008 2.7relative error of indication Ei mean deflection for a given value of increasing torque minus the corre
23、sponding value of applied torque NOTE 1For the purposes of this standard, relative error of indication is expressed as a percentage of applied torque. NOTE 2Relative error of indication is only used where the deflection is in units of torque. 2.8relative error of interpolation Eit difference between
24、 the value of the mean deflection for a given value of increasing torque and the corresponding calculated value of deflection for the given torque, obtained from a mathematically fitted curve NOTEFor the purposes of this standard, relative error of interpolation is expressed as a percentage of the c
25、omputed deflection for the given increasing torque. 2.9relative repeatability R1 closeness of the agreement between the results of two successive measurements from the same applied torque, carried out under the same conditions of measurement 2.10relative reproducibility R2 closeness of agreement bet
26、ween the results of successive measurements from the same applied torque, carried out under changed conditions of measurement 2.11relative residual deflection R0 maximum residual deflection obtained from all the series of torques NOTEFor the purposes of this standard, relative residual deflection is
27、 expressed as a percentage of the mean deflection for the maximum torque applied. 2.12relative reversibility R3 difference between the deflection obtained from the last given torque series applied in an increasing mode and the deflection obtained from the same given torque applied in a decreasing mo
28、de NOTEFor the purposes of this standard, relative reversibility is expressed as a percentage of the deflection of the last series for the given torque, applied in an increasing mode. 2.13residual deflection d0 algebraic difference between the indicator readings before and after the application of a
29、 single series of torques 2.14resolution r smallest discernable measurement interval on the torque measuring device indicator Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BSI 20083 BS 7882:2008 2.15torque pr
30、oduct of tangential force and length applied about a known centre of rotation 2.16torque measuring device system comprising an electrical, mechanical, hydraulic or optical torque measuring device, with associated instrumentation, including the automated logging of data when part of the device NOTETh
31、e instrumentation can be an electronic instrument, a mechanical device, i.e. a scale and pointer system, or a Bourdon tube instrument. 3 Preparation for calibration 3.1Reference standard 3.1.1Uncertainty of calibration torques Values for the maximum permissible uncertainty of the calibration torques
32、 applied for the determination of different classifications of the torque measuring device shall not exceed the values given in Table 1. Where a reference standard is used to determine a calibration torque, it shall conform to Table 1. 3.1.2Traceability of measurements All definitive measurements, s
33、uch as mass, length, time and temperature, shall be traceable to national standards; evidence of this shall be provided by a certificate of calibration. 3.2Condition and identification of a torque measuring device 3.2.1 Calibration shall not be commenced unless the torque measuring device is conside
34、red to be in good working order and is identified with a serial number. The maximum working torque shall first have been established. NOTEGood working order includes the drive components being of a sufficiently good fit to exert a minimum bias on the system. Table 1Uncertainty of calibration torques
35、 Class of torque measuring device to be calibrated Maximum permissible uncertainty of calibration torque appliedA) % 0.050.01 0.10.02 0.20.04 0.50.10 1.00.20 2.00.40 5.01.00 A) Using a coverage factor of k = 2 to give a confidence level of approximately 95%. Licensed Copy: London South Bank Universi
36、ty, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BS 7882:2008 4 BSI 2008 3.2.2 All parts of the torque measuring device shall be identified in accordance with 3.2.1, including the following, where applicable: a)signal cables; b)switch boxes; c)interfac
37、es; d)data acquisition systems; e)computers; and f)software (where information is available). 3.2.3 Where an electrical indicator used with a torque measuring device is replaced with another, the following requirements shall be met to ensure that the calibration is not invalidated. a)The original in
38、dicator shall have a valid calibration certificate, traceable to national standards, that gives the results of a calibration made in terms of the units to be measured. The indicator shall have been calibrated over a range equal to or greater than the range over which it is used with the torque measu
39、ring device. b)The replacement indicator shall have a resolution equal to or better than the indicator it is replacing and shall have a valid calibration certificate, traceable to national standards, that gives the results of a calibration made in terms of the units to be measured. The indicator sha
40、ll have been calibrated over a range equal to or greater than the range over which it is used with the torque measuring device. c)The date of calibration on the certificate for the original indicator shall not precede that of the certificate for the replacement indicator by more than 12 months. d)Th
41、e certificates for the two indicators show that the readings of the torque measuring device, as measured by the two indicators, agree with the values given below, over the range of the classification of the torque measuring device: 0.025% of indicated reading for a class 0.05 device; 0.050% of indic
42、ated reading for a class 0.1 device; 0.10% of indicated reading for a class 0.2 device; 0.25% of indicated reading for a class 0.5 device; 0.50% of indicated reading for a class 1.0 device; 1.00% of indicated reading for a class 2.0 device; 2.50% of indicated reading for a class 5.0 device. e)If it
43、is necessary to replace cables, the replacement cables shall be of the same specification as the originals to ensure that the calibration remains valid. Licensed Copy: London South Bank University, London South Bank University, Fri Feb 15 06:40:34 GMT+00:00 2008, Uncontrolled Copy, (c) BSI BSI 20085
44、 BS 7882:2008 3.3Resolution of the indicator NOTEAn indicator can be a direct reading display or the output of a data acquisition system. 3.3.1Analogue scale When the output of the torque measuring device is measured by an indicator with an analogue scale, i.e. a dial gauge or Bourdon tube instrumen
45、t, the resolution r shall be determined from the ratios between the width of the pointer and the centre-to-centre distance between two adjacent scale graduation marks (scale interval). NOTEThe ratios should be 1/2, 1/5 or 1/10. A spacing of at least 1.25 mm shall be used for the estimation of a tent
46、h of the division on the scale. When using an optical recognition system, i.e. video, the video frame rate shall be at least 10 times the display update being recorded. A vernier scale of dimensions appropriate to the analogue scale may be used to allow direct fractional reading of the instrument sc
47、ale division. 3.3.2Digital scale The resolution shall be considered to be one increment of the last active number of the numerical indicator. 3.3.3Variation of readings If the readings fluctuate by more than the value previously calculated for the resolution (with no torque applied to the instrument
48、), the resolution shall be deemed to be equal to half the range of fluctuation. 3.3.4Units The resolution r shall be converted to units of torque. 3.4Lower limit of calibration Tmin To ensure that the classification is consistent with the resolution of the torque indicator, a lower limit of calibrat
49、ion shall be determined. The calibration shall not be performed below this lower limit, given by the equation: Tmin = ar where: r is the resolution determined in accordance with 3.3 a has the following values: 4 000 for a class 0.05 torque measuring device; 2 000 for a class 0.1 torque measuring device; 1 000 for a class 0.2 torque measuring device; 400 for a class 0.5 torque measuring device; 200 for a class 1.0 torque measuring device; 100 for a class 2.0 torque measuring device; 4
链接地址:https://www.31doc.com/p-3736212.html