SIST EN ISO 376:2005
(Main)Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines (ISO 376:2004)
Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines (ISO 376:2004)
ISO 376:2004 covers the calibration of force-proving instruments used for the static verification of uniaxial testing machines (e.g. tension/compression testing machines) and describes a procedure for classifying these instruments.
ISO 376:2004 generally applies to force-proving instruments in which the force is determined by measuring the elastic deformation of a loaded member or a quantity which is proportional to it.
Metallische Werkstoffe - Kalibrierung der Kraftmessgeräte für die Prüfung von Prüfmachinen mit einachsiger Beanspruchung (ISO 376:2004)
In dieser Internationalen Norm ist die Kalibrierung von Kraftmessgeräten für die statische Prüfung einachsiger Prüfmaschinen (z. B. Zug-Druckprüfmaschinen) festgelegt. Es wird ein Verfahren für die Klassifizierung dieser Geräte beschrieben. Das Kraftmessgerät wird als das gesamte Gerät vom Kraftaufnehmer bis und einschließlich der Anzeigeeinrichtung definiert. Diese Internationale Norm gilt allgemein für Kraftmessgeräte, bei denen die Kraft durch Messung der elastischen Formveränderung eines Verformungskörpers oder einer ihr proportionalen Messgröße bestimmt wird.
Matériaux métalliques - Etalonnage des instruments de mesure de force utilisés pour la vérification des machines d'essais uniaxiaux (ISO 376:2004)
L'ISO 376:2004 a pour objet l'étalonnage des instruments de mesure de force utilisés pour la vérification statique des machines d'essais uniaxiaux (par exemple machines d'essai de traction/compression), et elle décrit une procédure de classification de ces instruments.
L'ISO 376:2004 s'applique généralement aux instruments de mesure de force dans lesquels la force est déterminée par la mesure de la déformation élastique d'un élément chargé ou par la mesure d'une grandeur proportionnelle à celle-ci.
Kovinski materiali – Kalibracija merilnikov sile, ki se uporabljajo za preverjanje preskusnih strojev z enoosno obremenitvijo (ISO 376:2004)
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kovinski materiali – Kalibracija merilnikov sile, ki se uporabljajo za preverjanje preskusnih strojev z enoosno obremenitvijo (ISO 376:2004)Metallische Werkstoffe - Kalibrierung der Kraftmessgeräte für die Prüfung von Prüfmachinen mit einachsiger Beanspruchung (ISO 376:2004)Matériaux métalliques - Etalonnage des instruments de mesure de force utilisés pour la vérification des machines d'essais uniaxiaux (ISO 376:2004)Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines (ISO 376:2004)77.040.10Mehansko preskušanje kovinMechanical testing of metalsICS:Ta slovenski standard je istoveten z:EN ISO 376:2004SIST EN ISO 376:2005en01-januar-2005SIST EN ISO 376:2005SLOVENSKI
STANDARDSIST EN ISO 376:2004SIST EN 10002-3:19961DGRPHãþD
SIST EN ISO 376:2005
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN ISO 376
November 2004 ICS 77.040.10
Supersedes EN ISO 376:2002
English version
Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines (ISO 376:2004) Matériaux métalliques - Etalonnage des instruments de mesure de force utilisés pour la vérification des machines d'essais uniaxiaux (ISO 376:2004)
This European Standard was approved by CEN on 20 October 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
B-1050 Brussels © 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 376:2004: ESIST EN ISO 376:2005
EN ISO 376:2004 (E) 2
Foreword
This document (EN ISO 376:2004) has been prepared by Technical Committee ISO/TC 164 "Mechanical testing of metals" in collaboration with Technical Committee ECISS/TC 1 "Steel - Mechanical testing", the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2005, and conflicting national standards shall be withdrawn at the latest by May 2005.
This document supersedes EN ISO 376 :2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 376:2004 has been approved by CEN as EN ISO 376:2004 without any modifications. SIST EN ISO 376:2005
Reference numberISO 376:2004(E)© ISO 2004
INTERNATIONAL STANDARD ISO376Third edition2004-11-01Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial testing machines Matériaux métalliques — Étalonnage des instruments de mesure de force utilisés pour la vérification des machines d'essais uniaxiaux
SIST EN ISO 376:2005
ISO 376:2004(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
©
ISO 2004 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel.
+ 41 22 749 01 11 Fax
+ 41 22 749 09 47 E-mail
copyright@iso.org Web
www.iso.org Published in Switzerland
ii © ISO 2004 – All rights reserved
SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved iii Contents Page Foreword.iv Introduction.v 1 Scope.1 2 Normative references.1 3 Terms and definitions.1 4 Symbols and their designations.1 5 Principle.2 6 Characteristics of force-proving instruments.3 6.1 Identification of the force-proving instrument.3 6.2 Application of force.3 6.3 Measurement of deflection.3 7 Calibration of the force-proving instrument.3 7.1 General.3 7.2 Resolution of the indicator.4 7.3 Minimum force.4 7.4 Calibration procedure.5 7.5 Assessment of the force-proving instrument.6 8 Classification of the force-proving instrument.7 8.1 Principle of classification.7 8.2 Classification criteria.8 8.3 Calibration certificate and duration of validity.8 9 Use of calibrated force-proving instruments.9 Annex A (informative)
Example of dimensions of force transducers and corresponding loading fittings.10 Annex B (informative)
Additional information.17 Bibliography.20
SIST EN ISO 376:2005
ISO 376:2004(E) iv © ISO 2004 – All rights reserved 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 376 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 1, Uniaxial testing. This third edition cancels and replaces the second edition (ISO 376:1999), which has been technically revised. SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved v Introduction No information is currently provided in this International Standard for determining the uncertainty of a
force-proving device or its indicator. An ISO/TC 164/SC 1 working group is currently developing procedures for determining the measurement uncertainty of force-proving devices. Until such information is provided in this International Standard, procedures for determining the measurement uncertainty of force-proving devices can be found in the two first documents listed in the Bibliography.
SIST EN ISO 376:2005
SIST EN ISO 376:2005
INTERNATIONAL STANDARD ISO 376:2004(E) © ISO 2004 – All rights reserved 1 Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial testing machines 1 Scope This International Standard covers the calibration of force-proving instruments used for the static verification of uniaxial testing machines (e.g. tension/compression testing machines) and describes a procedure for classifying these instruments. This International Standard generally applies to force-proving instruments in which the force is determined by measuring the elastic deformation of a loaded member or a quantity which is proportional to it. 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/IEC 17025, General requirements for the competence of testing and calibration laboratories 3 Terms and definitions For the purposes of this document, the following term and definition apply. 3.1 force-proving instrument whole assembly from the force transducer through to, and including, the indicator 4 Symbols and their designations Symbols and their designations are given in Table 1. SIST EN ISO 376:2005
ISO 376:2004(E) 2 © ISO 2004 – All rights reserved Table 1 — Symbols and their designations Symbol Unit Designation b % Relative reproducibility error with rotation b′ % Relative repeatability error without rotation Ff N Maximum capacity of the transducer FN N Maximum calibration force fc % Relative interpolation error f0 % Relative zero error if — Readinga on the indicator after removal of force io — Readinga on the indicator before application of force r N Resolution of the indicator v % Relative reversibility error of the force-proving instrument X — Deflection with increasing test force Xa — Computed value of deflection X′ — Deflection with decreasing test force Xmax — Maximum deflection from runs 1, 3 and 5 Xmin — Minimum deflection from runs 1, 3 and 5 XN — Deflection corresponding to the maximum calibration force rX — Average value of the deflections with rotation wrX — Average value of deflections without rotation a Reading value corresponding to the deflection.
5 Principle Calibration consists of applying precisely-known forces to the force transducer and recording the data from the indicator, which is considered an integral part of the force-proving instrument. When an electrical measurement is made, the indicator may be replaced by another indicator and the
force-proving instrument need not be recalibrated provided the following conditions are fulfilled. a) The original and replacement indicators have calibration certificates, traceable to national standards, which give the results of calibration in terms of electrical base units (volt, ampere). The replacement indicator shall be calibrated over a range equal to or greater than the range for which it is used with the force-proving instrument and the resolution of the indicator shall be at least equal to the resolution of the indicator when it is used with the force-proving instrument. b) The units and excitation source of the replacement indicator should be respectively of the same quantity (e.g. 5 V, 10 V) and type (e.g. AC or DC carrier frequency). c) The uncertainty of each indicator (both the original and the replacement indicators), shall not significantly influence the uncertainty of the whole assembly of the force-proving instrument. It is recommended that the uncertainty of the replacement indicator should be no greater than 1/3 of the uncertainty of the entire system. SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved 3 6 Characteristics of force-proving instruments 6.1 Identification of the force-proving instrument All the elements of the force-proving instrument (including the cables for electrical connection) shall be individually and uniquely identified, e.g. by the name of the manufacturer, the model and the serial number. For the force transducer, the maximum working force shall be indicated. 6.2 Application of force The force transducer and its loading fittings shall be designed so as to ensure axial application of force, whether in tension or compression. Examples of loading fittings are given in Annex A. 6.3 Measurement of deflection Measurement of the deflection of the loaded member of the force transducer may be carried out by mechanical, electrical, optical or other means with adequate accuracy and stability. The type and the quality of the deflection measuring system determine whether the force-proving instrument is classified only for specific calibration forces or for interpolation (see Clause 7). Generally, the use of force-proving instruments with dial gauges as a means of measuring the deflection is limited to the forces for which the instruments have been calibrated. The dial gauge, if used over a long travel, may contain large localized periodic errors which produce an uncertainty too great to permit interpolation between calibration forces. The dial gauge may be used for interpolation if its periodic error has a negligible influence on the interpolation error of the force-proving instrument. 7 Calibration of the force-proving instrument 7.1 General 7.1.1 Preliminary measures Before undertaking the calibration of the force-proving instrument, ensure that this instrument is able to be calibrated. This can be done by means of preliminary tests such as those defined below and given as examples. 7.1.2 Overloading test This optional test is described in Clause B.1. 7.1.3 Verification relating to application of forces Ensure =that the attachment system of the force-proving instrument allows axial application of the force when the instrument is used for tensile testing; =that there is no interaction between the force transducer and its support on the calibration machine when the instrument is used for compression testing. Clause B.2 gives an example of a method that can be used. SIST EN ISO 376:2005
ISO 376:2004(E) 4 © ISO 2004 – All rights reserved NOTE Other tests can be used, e.g. a test using a flat-based transducer with a spherical button or upper bearing surface. 7.1.4 Variable voltage test This test is left to the discretion of the calibration service. For force-proving instruments requiring an electrical supply, verify that a variation of ± 10 % of the line voltage has no significant effect. This verification can be carried out by means of a force transducer simulator or by another appropriate method. 7.2 Resolution of the indicator 7.2.1 Analogue scale The thickness of the graduation marks on the scale shall be uniform and the width of the pointer shall be approximately equal to the width of a graduation mark. The resolution, r, of the indicator shall be obtained from the ratio between the width of the pointer and the centre-to-centre distance between two adjacent scale graduation marks (scale interval), the recommended ratios being 1:2, 1:5 or 1:10, a spacing of 1,25 mm or greater being required for the estimation of a tenth of the division on the scale. A vernier scale of dimensions appropriate to the analogue scale may be used to allow direct fractional reading of the instrument scale division. 7.2.2 Digital scale The resolution is considered to be one increment of the last active number on the numerical indicator. 7.2.3 Variation of readings If the readings fluctuate by more than the value previously calculated for the resolution (with no force applied to the instrument), the resolution shall be deemed to be equal to half the range of fluctuation. 7.2.4 Units The resolution, r, shall be converted to units of force. 7.3 Minimum force Taking into consideration the accuracy with which the deflection of the instrument may be read during calibration or during its subsequent use for verifying machines, the minimum force applied to a force-proving instrument shall comply with the two following conditions: a) the minimum force shall be greater than or equal to: =4 000 × r for class 00 =2 000 × r for class 0,5 =1 000 × r for class 1 =500 × r for class 2 b) the minimum force shall be greater than or equal to 0,02 Ff. SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved 5 7.4 Calibration procedure 7.4.1 Preloading Before the calibration forces are applied, in a given mode (tension or compression), the maximum force shall be applied to the instrument three times. The duration of the application of each preload shall be between 1 min and 1,5 min. 7.4.2 Procedure Carry out the calibration by applying two series of calibration forces to the force-proving instrument with increasing values only, without disturbing the device. Then apply at least two further series of increasing and decreasing values. Between each of the further series of forces, rotate the force-proving instrument symmetrically on its axis to positions uniformly distributed over 360° (i.e. 0°, 120°, 240°). If this is not possible, it is permissible to adopt the following positions: 0°, 180° and 360° (see Figure 1).
Figure 1 — Positions of the force-proving instrument For the determination of the interpolation curve, the number of forces shall be not less than eight, and these forces shall be distributed as uniformly as possible over the calibration range. NOTE 1 If a periodic error is suspected, it is recommended that intervals between the forces which correspond to the periodicity of this error be avoided. NOTE 2 This procedure determines only a combined value of hysteresis of the device and of the calibration machine. Accurate determination of the hysteresis of the device may be performed on dead-weight machines. For other types of calibration machines, their hysteresis should be considered. SIST EN ISO 376:2005
ISO 376:2004(E) 6 © ISO 2004 – All rights reserved The force-proving instrument shall be pre-loaded three times to the maximum force in the direction in which the subsequent forces are to be applied. When the direction of loading is changed, the maximum force shall be applied three times in the new direction. The readings corresponding to no force shall be noted after waiting at least 30 s after the force has been totally removed. NOTE 3 There should be a wait of at least 3 min between subsequent measurement series. Instruments with detachable parts shall be dismantled, as for packaging and transport, at least once during calibration. In general, this dismantling shall be carried out between the second and third series of calibration forces. The maximum force shall be applied to the force-proving instrument at least three times before the next series of forces is applied. Before starting the calibration of an electrical force-proving instrument, the zero signal may be noted (see Clause B.3). 7.4.3 Loading conditions The time interval between two successive loadings shall be as uniform as possible, and no reading shall be taken within 30 s of the start of the force change. The calibration shall be performed at a temperature stable to within ± 1 °C, this temperature shall be within the range 18 °C to 28 °C and shall be recorded. Sufficient time shall be allowed for the force-proving instrument to attain a stable temperature. NOTE When it is known that the force-proving instrument is not temperature-compensated, care should be taken to ensure that temperature variations do not affect the calibration. Strain gauge transducers shall be energized for at least 30 min before calibration. 7.4.4 Determination of deflection A deflection is defined as the difference between a reading under force and a reading without force. NOTE This definition of deflection applies to output readings in electrical units as well as to output readings in length units. 7.5 Assessment of the force-proving instrument 7.5.1 Relative reproducibility and repeatability errors, b and b′ These errors are calculated for each calibration force and in both cases viz. with rotation of the force-proving instrument (b) and without rotation (b′), using the following equations: maxminr100XXbX−=× where 135r3XXXX++= 21wr100XXbX−′=× where 12wr2XXX+= SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved 7 7.5.2 Relative interpolation error, fc This error is determined using a first-, second-, or third-degree equation giving the deflection as a function of the calibration force. The equation used shall be indicated in the calibration report. The relative interpolation error shall be calculated from the equation: raca100XXfX−=× 7.5.3 Relative zero error, f0 The zero shall be recorded before and after each series of tests. The zero reading shall be taken approximately 30 s after the force has been completely removed. The relative zero error is calculated from the equation: fo0N100iifX−=× The maximum relative zero error evaluated should be considered. 7.5.4 Relative reversibility error, v The relative reversibility error is determined at each calibration, by carrying out a verification with increasing forces and then with decreasing forces. The difference between the values obtained for both series with increasing forces and with decreasing forces enables the relative reversibility error to be calculated using the following equations: 4313100XXvX′−=× 6525100XXvX′−=× v is calculated as the mean value of v1 and v2: 122vvv+= 8 Classification of the force-proving instrument 8.1 Principle of classification The range for which the force-proving instrument is classified is determined by considering each calibration force, one after the other, starting with the maximum force and decreasing to the lowest calibration force. The classification range ceases at the last force for which the classification requirements are satisfied. The force-proving instrument can be classified either for specific forces or for interpolation. SIST EN ISO 376:2005
ISO 376:2004(E) 8 © ISO 2004 – All rights reserved 8.2 Classification criteria 8.2.1 The range of classification of a force-proving instrument shall at least cover the range 50 % to 100 % of FN. 8.2.2 For instruments classified only for specific forces, the criteria which shall be considered are: =the relative reproducibility and repeatability errors; =the relative zero error; =the relative reversibility error. 8.2.3 For instruments classified for interpolation, the following criteria shall be considered: =the relative reproducibility and repeatability errors; =the relative interpolation error; =the relative zero error; =the relative reversibility error. Table 2 gives the values of these different parameters in accordance with the class of the force-proving instrument and the uncertainty of the calibration forces. Table 2 — Characteristics of force-proving instruments
Relative error of the force-proving instrument
% Uncertainty of applied calibration force k = 2 of reproducibility of repeatability of interpolation of zero of reversibility % Class b b′ fc f0 v
00 0,05 0,025 ± 0,025 ± 0,012 0,07 ± 0,01 0,5 0,10 0,05 ± 0,05 ± 0,025 0,15 ± 0,02 1 0,20 0,10 ± 0,10 ± 0,050 0,30 ± 0,05 2 0,40 0,20 ± 0,20 ± 0,10 0,50 ± 0,10
8.3 Calibration certificate and duration of validity 8.3.1 If a force-proving instrument has satisfied the requirements of this International Standard at the time of calibration, the calibration authority shall draw up a certificate, in accordance with ISO/IEC 17025, stating at least the following information: a) identity of all elements of the force-proving instrument and loading fittings and of the calibration machine; b) the mode of force application (tension/compression); c) that the instrument is in accordance with the requirements of preliminary tests; d) the class and the range (or forces) of validity; e) the date and results of the calibration and, when required, the interpolation equation; f) the temperature at which the calibration was performed. SIST EN ISO 376:2005
ISO 376:2004(E) © ISO 2004 – All rights reserved 9 8.3.2 For the purposes of this International Standard, the maximum period of validity of the certificate shall not exceed 26 months. A force-proving instrument shall be recalibrated when it sustains an overload higher than the test overload (see Clause B.1) or after repair. 9 Use of calibrated force-proving instruments Force-proving instruments shall be loaded in accordance with the conditions under which they were calibrated. Precautions shall be taken to prevent the instrument from being subjected to forces greater than the maximum calibration force. Instruments classified only for specific forces shall be used only for these forces. Instruments classified for interpolation may be used for any force in the interpolation range. If a force-proving instrument is used at a temperature other than the calibration temperature, the deflection of the instrument shall be, if necessary, corrected for any temperature variation (see Clause B.4). NOTE A change of zero of the unloaded force transducer indicates plastic deformation due to overloading of the force transducer. Permanent long-time drifting indicates the moisture influence of the strain gauges base or a bonding defect of the strain gauges.
SIST EN ISO 376:2005
ISO 376:2004(E) 10 © ISO 2004 – All rights reserved Annex A (informative)
Example of dimensions of force transducers and corresponding loading fittings A.1 General In order to calibrate force transducers in force standard machines and to enable easy axial installation in the materials testing machines to be verified, the following design specifications and dimensions may be considered. A.2 Tensile force transducers To aid assembly, it is recommended that the clamping heads on the face be machined down to the core diameter over a length of about two threads. See Table A.1. The centring bores used in the manufacture of the force transducer should be retained. Table A.1 — Dimensions of tensile force transducers for nominal forces of not less than 10 kN Maximum overall length b Size of external
thread of heads c Minimum length of thread Maximum width
or diameter Maximum (nominal)
force of force-proving instrumenta mm
mm mm 10 kN to 20 kN 500 M20 × 1,5 d 16 110 40 kN and
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.