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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN ISO 14744-3:2001 Th
2、e European Standard EN ISO 14744-3:2000 has the status of a British Standard ICS 25.160.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Welding Acceptance inspection of electron beam welding machines Part 3: Measurement of beam current characteristics Licensed Copy: sheffie
3、ldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 April 2001 BSI 04-2001 IS
4、BN 0 580 34196 8 BS EN ISO 14744-3:2001 Amendments issued since publication Amd. No.DateComments National foreword This British Standard is the official English language version of EN ISO 14744-3:2000. It is identical with ISO 14744-3:2000. The UK participation in its preparation was entrusted to Te
5、chnical Committee WEE/47, Miscellaneous welding standards, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor rela
6、ted international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative
7、 references to international publications with their corresponding European publications. The British Standards which implement these international or European publications may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by usin
8、g the Find facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity fr
9、om legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN ISO title page, pages 2 to 8, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Licensed Copy: sheffieldun
10、 sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 14744-3 April 2000 ICS 25.160.00 English version Welding - Acceptance inspection of electron beam welding machines - Part 3: Measurement of beam current character
11、istics (ISO 14744-3:2000) Soudage - Essais de rception des machines de soudage par faisceau dlectrons - Partie 3: Mesure des caractristiques de lintensit du faisceau (ISO 14744- 3:2000) Schweien - Abnahmeprfung von Elektronenstrahl- Schweimaschinen - Teil 3: Messen des Strahlstrom- Kenngren (ISO 147
12、44-3:2000) This European Standard was approved by CEN on 3 January 2000. 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 bibliogra
13、phical 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 C
14、EN 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, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway
15、, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Central Secretariat: rue de Stassart, 36 B-1050 Brussels 2000 CENAll rights of exploitation in any form and by any means reserved worldwide
16、for CEN national Members. Ref. No. EN ISO 14744-3:2000 E Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 2 EN ISO 14744-3:2000 Contents Page Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . .3 1Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . .4 3Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 4Test arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 4.1
19、General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 4.2Faraday cup and electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 5Measurement procedure . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.2Current losses . . . . . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.3Measuring the ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.4Measuring the stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.5Measuring the reproducibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 6Problems in measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、 . . . . . . .8 7Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 3 EN ISO 14744-3:2000 Foreword Th
24、e text of EN ISO 14744-3:2000 has been prepared by Technical Committee CEN/TC 121 “Welding“, the secretariat of which is held by DS, in collaboration with Technical Committee ISO/TC 44 “Welding and allied processes“. This European Standard shall be given the status of a national standard, either by
25、publication of an identical text or by endorsement, at the latest by October 2000, and conflicting national standards shall be withdrawn at the latest by October 2000. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to impl
26、ement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. This draft European Standard is composed of the six following parts: Part
27、1: Principles and acceptance conditions; Part 2: Measurement of accelerating voltage characteristics; Part 3: Measurement of beam current characteristics; Part 4: Measurement of welding speed; Part 5: Measurement of run-out accuracy; Part 6: Measurement of stability of spot position. Licensed Copy:
28、sheffieldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 4 EN ISO 14744-3:2000 1 Scope This standard is intended for use when the beam current of electron beam welding machines complying with EN ISO 14744-1:2000 is to be measured in connection with an acceptan
29、ce inspection. It provides essential information on the procedure and apparatus to be used for making the measurements. The beam current is one of the significant parameters in electron beam welding. When the beam current impinges on the workpiece, it should be stable and reproducible within given s
30、hort-term and long-term limits. The purpose of the measurement is thus to check whether the variations in beam current are within these limits. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are
31、 cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest ed
32、ition of the publication referred to applies. EN ISO 14744-1:2000 Welding Acceptance inspection of electron beam welding machines Part 1: Principles and acceptance conditions (ISO 14744-1 : 2000) 3 Terms and definitions For the purposes of this European Standard, the following term and definition ap
33、plies, 3.1 Beam current current produced by the sum of the accelerated electrons before these impinge on the workpiece, measured at a distance roughly corresponding to the work distance NOTE Although this current is somewhat lower than the electron current emitted from the cathode, it is the factor
34、crucial to the welding procedure. 4 Test arrangement 4.1 General The beam current is to be measured at specified levels covering the entire power range of the welding machine. As there is no solid conductor, a Faraday cup shall be used that, as far as possible, collects all the electrons emitted fro
35、m the cathode and causes them to flow to earth through a resistor of given rating (see figure 1). The Faraday cup shall be designed so that it: a) sustains the thermal load even at high beam powers over a period equal to several times the measurement period; b) prevents, as far as possible, the esca
36、pe of primary and secondary electrons and charged vapour. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 5 EN ISO 14744-3:2000 Key 1Electron beam4Insulation7Screened cable to oscilloscope 2Faraday cup5Work table8Feedthrough to pass cab
37、le through work chamber wall 3Faraday cup orifice6Resistor Figure 1 - Diagrammatic representation of beam current measurement using a Faraday cup Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 6 EN ISO 14744-3:2000 4.2 Faraday cup and
38、electrical connections Figure 2 and table 1 provide recommended dimensions on the design of Faraday cups of copper for various beam powers up to 30 kW which may be adapted to meet practical requirements. For beam powers above 15 kW, water cooling is necessary. Table 1 - Faraday cup. Recommended dime
39、nsions (see figure 2) values in mm Maximum accelerating voltage, in kV Maximum beam power, in kWd1DlLn d2 601561009022010 6 60301017027044510 10 1506610010020010 6 150301010030050010 10 NOTE 1 Dimension d1 should be kept small enough just to accommodate a focused electron beam including fringe beam,
40、 while preventing the escape of electrons. Key 1 Electron beam 2 Copper 3 Ceramic insulator Figure 2 - Faraday cup assembly NOTE 2 The bores around the Faraday cup barrel allow a rapid escape of metal vapour whilst avoiding escape of electrons. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19
41、09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 7 EN ISO 14744-3:2000 The Faraday cup shall be insulated electrically from the work table by means of a ceramic insulator. A resistor shall be connected between the Faraday cup and earth at a sufficient distance to prevent it being thermally i
42、nfluenced. As shown in figure 1, a screened cable shall be passed to the measuring instrument via a feed- through in the work chamber wall. 5 Measurement procedure 5.1 General The measurements shall be carried out with the welding machine set as specified in 6.2 of EN ISO 14744-1:2000. 5.2 Current l
43、osses The beam current entering the Faraday cup shall be measured and compared with the emission current (i.e. the rated beam current). Excessive deviations indicate inaccurate positioning of the electron beam with respect to the diameter of the Faraday cup orifice, d1, or adjustment errors in the b
44、eam source which are to be corrected. For all operations, when using the Faraday cup, the electron beam shall be focused on the centre of the orifice (see figure 2). Beam parameters and position of the Faraday cup shall be adjusted to obtain maximum monitored voltage prior to testing. 5.3 Measuring
45、the ripple An oscilloscope shall be used to determine the maximum range (peak-to-peak value) in the instantaneous value Ub of the monitored voltage, Ub. The percentage deviation shall be calculated as follows: where Ub max, Ub min and Ub are maximum, minimum and average values observed during the pe
46、riod of observation (see figure 3). 5.4 Measuring the stability The average voltage shall be recorded continuously for a given operating period, using an instrument eliminating ripple. The percentage deviation shall be calculated as follows: whichever is the largest and where Ub max and Ub min are m
47、aximum and minimum observed values and Ub is the initial value. 5.5 Measuring the reproducibility The beam current shall be switched on and the average monitored voltage shall be measured, using an instrument eliminating ripple. The specified beam current shall subsequently be switched off and on se
48、veral times and the corresponding average monitored voltages shall be recorded. The reproducibility shall be calculated as follows: whichever is the greater where Ub max and Ub min are maximum and minimum average values observed and Ub is the initial value. Licensed Copy: sheffieldun sheffieldun, na
49、, Sun Nov 19 09:19:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 8 EN ISO 14744-3:2000 a) Measurement of Ubb) Measurement of peak-to-peak value (greater sensitivity of indication in the Y direction than for item a) Figure 3 - Screen indications for measuring the beam current ripple 6 Problems in measurement The problem most frequently met with, particularly when measuring high beam currents, is a high frequency fluctuation of the beam current on the display, which is associated with an over-large fusion area in the bottom of
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