BS PD ISO TR 18491-2015 Welding and allied processes Guidelines for measurement of welding energies《焊接及相关工艺 焊接能量测量指南》.pdf

1、BSI Standards Publication PD ISO/TR 18491:2015 Welding and allied processes Guidelines for measurement of welding energiesPD ISO/TR 18491:2015 PUBLISHED DOCUMENT National foreword This Published Document is the UK implementation of ISO/TR 18491:2015. The UK participation in its preparation was entru

2、sted to Technical Committee WEE/-/1, Briefing committee for welding. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct appli

3、cation. The British Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 85094 3 ICS 25.160.01 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strateg

4、y Committee on 31 May 2015. Amendments issued since publication Date Text affectedPD ISO/TR 18491:2015 ISO 2015 Welding and allied processes Guidelines for measurement of welding energies Soudage et techniques connexes Lignes directrices pour le mesurage des nergies de soudage TECHNICAL REPORT ISO/T

5、R 18491 Reference number ISO/TR 18491:2015(E) First edition 2015-05-01PD ISO/TR 18491:2015ISO/TR 18491:2015(E)ii ISO 2015 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced

6、 or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO

7、 copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.orgPD ISO/TR 18491:2015ISO/TR 18491:2015(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 General 2 5

8、Apparatus . 2 6 Determination of arc energy 2 7 Measurement parameters 3 7.1 General . 3 7.2 Arc voltage 3 7.3 Welding current . 4 7.4 Instantaneous energy or instantaneous power 4 7.5 Travel speed and length 4 8 Calibration and validation of measuring instruments . 4 Annex A (informative) Range of

9、power supply types and measurement methods 5 Bibliography 7 ISO 2015 All rights reserved iii Contents PagePD ISO/TR 18491:2015ISO/TR 18491:2015(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of

10、 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

11、, 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. The procedures used to develop this document and those intended for its further maintenance are described in the IS

12、O/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibil

13、ity 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of pa

14、tent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as in

15、formation about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword Supplementary information. The committee responsible for this document is ISO/TC 44, Welding and allied processes, Subcommittee SC 10, Unification of requirements in the fie

16、ld of metal welding.iv ISO 2015 All rights reservedPD ISO/TR 18491:2015ISO/TR 18491:2015(E) Introduction Welding “arc energy” or “heat input” are fundamental values used to manage the consistency of weld metal and heat-affected zone properties. ISO 15614 requires the measurement of the welding energ

17、ies implemented during a welding procedure qualification, but it does not give details about the methods to be used. Likewise, during the construction of a welded assembly, inspectors should make sure that the welding energies comply with the Welding Procedure Specification (WPS). But again, the det

18、ails of the methods to be used are not specified. As a consequence, there may be a lack of consistency between the methods used to measure the welding energies during welding of the test piece and the methods used during the manufacturing process. This is a potential source of error which could have

19、 implications on the safety or quality of a welded component or structure. Moreover, the latest technological breakthroughs in microprocessors and electrical power manipulation have yielded welding power sources and control systems that are capable of generating complex waveforms. However, these con

20、trol systems and waveforms increase the difficulties related to voltage and current intensity measurements, as their values are manipulated at frequencies which can reach thousands of Hertz. The measuring instruments generally used by inspectors, such as TRMS clamp meters, can no longer be relied on

21、 to correctly measure the welding energy since differences exceeding 30 % with respect to the true energy can sometimes be found. This Technical Report provides guidance on how to accurately measure welding energy and calculate heat input, both in the case of traditional welding systems and those th

22、at employ complex waveforms. ISO 2015 All rights reserved vPD ISO/TR 18491:2015PD ISO/TR 18491:2015Welding and allied processes Guidelines for measurement of welding energies 1 Scope This Technical Report presents the guidelines for measuring the parameters needed to calculate arc energies for arc w

23、elding processes. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (i

24、ncluding any amendments) applies. ISO 15607, Specification and qualification of welding procedures for metallic materials General rules ISO 17662, Welding Calibration, verification and validation of equipment used for welding, including ancillary activities ISO/TR 17671 (all parts), Welding Recommen

25、dations for welding of metallic materials 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in ISO 15607 and ISO/TR 17671 (all parts) and the following apply. 3.1 arc energy E product of welding voltage and current divided by travel speed of welding Note 1

26、 to entry: The often-used term “heat input” is more correctly the arc energy modified by an arc efficiency factor. 3.2 waveform controlled welding welding process modification of the voltage and/or current wave shape to control characteristics such as droplet shape, penetration, wetting, bead shape,

27、 or transfer mode(s) 3.3 instantaneous energy IE welding energy determined by summing the product of current and voltage measurements made at rapid intervals which capture brief changes in the welding waveform 3.4 instantaneous power IP welding power determined by averaging the product of current an

28、d voltage measurements made over time at rapid intervals which capture brief changes in the welding waveform 3.5 run out length length of a run produced by the melting of a covered electrode SOURCE: ISO/TR 17671-2:2002, 3.2 TECHNICAL REPORT ISO/TR 18491:2015(E) ISO 2015 All rights reserved 1PD ISO/T

29、R 18491:2015ISO/TR 18491:2015(E) 4 General The term “heat input” is often used to describe two different concepts. In this Technical Report, these concepts are identified as heat input and as arc energy. Determination of heat input involves multiplication by a unitless thermal efficiency factor whil

30、e arc energy does not. Other than that distinction, the measurement methods for both are identical. The arc energy is determined as shown in Formulae (1), (2), and (3). The symbols shown in Table 1 are used for all formulae. Table 1 Symbols of terms used Abbreviations and symbols Term Unit I Arc wel

31、ding current A L Length of a run mm U Arc voltage V v Travel speed mm/s E Arc energy kJ/mm IE Instantaneous energy J IP Instantaneous power J/s Formula (1) provides the arc energy using arc welding current and arc voltage. (1) Formula (2) gives the arc energy using instantaneous energy. (2) Formula

32、(3) gives the arc energy using instantaneous power. (3) 5 Apparatus Usual equipment and, in particular, the following: 5.1 Clamp meter or any equivalent current, instantaneous energy, or power-measuring device. 5.2 Voltmeter. 5.3 Time-measuring device, such as stopwatch. 5.4 Distance-measuring devic

33、e, such as steel rule, tape measure. 6 Determination of arc energy Three methods can be used to determine arc energy: Method A: by calculation using arc welding current, arc voltage, and welding speed Formula (1);2 ISO 2015 All rights reservedPD ISO/TR 18491:2015ISO/TR 18491:2015(E) Method B: by cal

34、culation using instantaneous energy measurements and length of the run Formula (2); Method C: by calculation using instantaneous power measurements and welding speed Formula (3). For non-waveform-controlled welding, method A, B, or C can be used indifferently. For waveform-controlled welding, method

35、 B or C should be used as method A can introduce mistakes up to 70 %. All pulsed welding processes, for example, pulsed gas metal arc welding, are waveform-controlled welding processes. Power sources that are sold as synergic, programmable, or microprocessor-controlled are generally capable of wavef

36、orm-controlled welding. If any doubt exists on whether waveform-controlled welding is being performed, the welding equipment manufacturer should be consulted. For multi-arc welding, the arc energy is measured for each arc. Table A .1 and Figure A.1 provide the range of power supply t ypes and measur

37、ement methods that support production welding based on power supply type and measurement method used to weld the test piece. 7 Measurement parameters 7.1 General When method A is used, measure arc voltage (7.2), welding current (7.3), and travel speed (7.5). When method B is used, measure instantane

38、ous energy (7.4) and length of the run (7.5). When method C is used, measure instantaneous power (7.4) and travel speed (7.5). 7.2 Arc voltage The voltage values should be measured as close to the arc as practical in order to prevent the measurement error due to voltage drop in the welding cables. N

39、OTE The voltage measurement is affected by cable size, length, and connection quality and has to be taken into account during measurement. The position of the connectors shall be recorded in the WPQR to provide consistency of the measurement during production. The first one should be connected to th

40、e earth clamp on the work piece and the second one should be connected as described in Table 2. Table 2 Preferred arc voltage measurement locations Process number according ISO 4063 Process Measurement location 11(x) Metal arc welding without gas protection (and all its sub- groups) Connection devic

41、e on power source 12(x) Submerge arc welding (and all its subgroups) Welding head 13(x) Gas-shielded metal arc welding (and all its subgroups) Connection in wire feeder 14(x) Gas-shielded arc welding with non-consumable tungsten elec- trode (and all its subgroups) Connection device on power source 1

42、5(x) Plasma arc welding (and all its subgroups) Connection device on power source ISO 2015 All rights reserved 3PD ISO/TR 18491:2015ISO/TR 18491:2015(E) 7.3 Welding current Measure the welding current using a shunt or a clamp meter on a straight portion of the welding cable. The current measurement

43、should include all earth-connection cables or current lead cables, if multiple earth-connection cables or current lead cables are used. It is inaccurate to measure the current intensity on a single cable and multiply by the total number of cables, or to mix the earth-connection cables and current le

44、ad cables in one measurement. For measurements of arc welding current below the recommended range of the clamp meter, the cable may be looped through the clamp, in which case the measured value is divided by the number of loops. 7.4 Instantaneous energy or instantaneous power Measurement of instanta

45、neous energy or instantaneous power should utilize a welding power source or external meter that is capable of calculating and displaying energy or power. Both the sampling rate and the calculation rate should be sufficient to capture the changes in the welding waveform (typically, a sampling rate a

46、t least 10 times the frequency of the wave form is used). When using external meters, the same guidelines as 7.2 and 7.3 apply. These meters are often identified by the terms “true energy”, “true power”, or “power factor”. Meters identified by the terms “kVA”, “DC power”, or “average power” do not g

47、enerally meet these requirements. 7.5 Travel speed and length To determine the travel speed, a run is deposited and the time elapsed between arc starting and arc extinguishing is measured. After completion of the run, its length is measured (see Figure 1). The travel speed is obtained by dividing th

48、e length of the run by the elapsed time. For mechanized and automatic welding, the travel speed can also be determined by measuring the time required to cover a distance without making a weld run or by using meters that are part of the equipment. Key 1 crater at the end of the run 2 start of the run

49、 L length of the run Figure 1 Length of the run The length of the run corresponds to the distance between the start of the run and the middle of the crater at the end of the run, as illustrated in Figure 1. 8 Calibration and validation of measuring instruments Calibrate or validate measuring equipment according to ISO 17662.4 ISO 2015 All rights reservedPD ISO/TR 18491:2015ISO/TR 18491:2015(E) Annex A (informative) Range of power supply types and measurement methods