1、 Reference number ISO/TR 27609:2007(E) ISO 2007TECHNICAL REPORT ISO/TR 27609 First edition 2007-06-15 Vibration in hand-held tools Vibration measurement methods for grinders Evaluation of round-robin test Vibration des machines moteur portatives Mthodes de mesure des vibrations des meuleuses valuati
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5、cretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 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 wr
6、iting from either ISO at the address below or ISOs 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 copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedISO/TR 2
7、7609:2007(E) ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Symbols and abbreviated terms 1 3 Method 3 4 Description of two test methods evaluated 3 4.1 Unbalance disc test method.3 4.2 Grinding test method 4 5 Results 4 5.1 General4 5.2 Spread of methods 5 5.2
8、.1 Unbalance disc test .5 5.2.2 Grinding test.8 5.2.3 Correlation between no-load and grinding vibration.10 5.3 Unbalance disc test for simulating real grinding .12 5.4 Measurements repeated over time.13 6 Conclusion .14 6.1 Unbalance disc test .14 6.2 Grinding test.14 6.3 Repeatability.14 Annex A (
9、informative) Test instructions “Instruction for participants in the 2003 round-robin test on grinders. The aim is to evaluate the proposed changes to ISO 8662-4:1994 in document ISO/TC 118/SC 3/WG 3 N211”.15 Annex B (informative) Diagrams21 Annex C (informative) List of grinders and laboratories.28
10、Bibliography 29 ISO/TR 27609:2007(E) iv ISO 2007 All rights reservedForeword 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 technica
11、l 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 wit
12、h 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 Inter
13、national 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. In exceptional circumstances, when a technical committee has collected data of a dif
14、ferent kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed
15、until the data it provides are considered to be no longer valid or useful. 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/TR 27609 was prepared
16、by Technical Committee ISO/TC 118, Compressors and pneumatic tools, machines and equipment, Subcommittee SC 3, Pneumatic tools and machines. ISO/TR 27609:2007(E) ISO 2007 All rights reserved v Introduction At the time of publication of this Technical Report, it was intended that ISO 8662-4, which de
17、als with hand- held grinders, be revised and harmonized with ISO 20643. The latter International Standard requires, among other provisions, that the vibration emission measurements be made in three directions, with the declared values related to the upper quartile of real-use vibration. A round-robi
18、n test was made to gain an idea of the upper limits of real-use vibration and to establish a test method fulfilling the three-direction requirement. Four grinders of different sizes both with, and without, auto-balancing units were measured by seven laboratories. Measurements were made according to
19、detailed test instructions. The laboratories were manufacturers and health and safety authorities in Europe. Two methods were evaluated by the round-robin test: one using a redesigned unbalance disc and the other by grinding on mild steel using standard type 27 grinding wheels. The result shows that
20、 the unbalance disc test method can be used for estimating the real-use vibration as long as the grinder is not fitted with an auto-balancing unit. If such a unit is fitted, the real-use vibration is underestimated by that method. Methods for estimating the real-use vibration level for grinders fitt
21、ed with auto-balancing units are not discussed in this Technical Report. A real grinding test is not suitable for obtaining a declared value, as the spread for this method is large. Furthermore, in order to obtain enough data to handle the large spread, the time consumption is unreasonably high. TEC
22、HNICAL REPORT ISO/TR 27609:2007(E) ISO 2007 All rights reserved 1 Vibration in hand-held tools Vibration measurement methods for grinders Evaluation of round-robin test 1 Scope This Technical Report presents an evaluation of a round-robin test of vibration measurement methods for determining vibrati
23、on in hand-held grinders. The aim of the round-robin test was to establish a test method that could meet the requirement of ISO 20643 for measurement of vibration emissions in three directions, for accordance with the planned-to-be-revised ISO 8662-4. The value obtained by such a test method must co
24、rrespond to the highest vibration values likely to occur under typical and normal working conditions of the machine, i.e. the upper quartile of the vibration in real use. This acknowledges that the upper boundary of “typical and normal” conditions can be exceeded by some conditions of “real use”. Vi
25、bration at grinding can mainly be divided into vibration caused by unbalance of the grinding wheel and process vibration generated by the contact between the grinding wheel and the work piece. The unbalance part has been shown to be the greater of the two and ISO 8662-4 is based on this. In this Tec
26、hnical Report, the test method consists of a number of averaged measurements using an unbalance disc, with an unbalance corresponding to the upper limit of the unbalances found among real grinding wheels. Whereas ISO 8662-4 covers all types of hand-held grinders, the round-robin test presented in th
27、is Technical Report was based on grinding with depressed centre-wheels, one of the most common grinding applications. The types of grinder used in the round-robin test are given in Table 1. Table 1 Grinder types and sizes used in test Wheel size Type of grinder 125 mm (5) 230 mm (9) Pneumatic Withou
28、t auto-balancing unit With auto-balancing unit Electric With auto-balancing unit Without auto-balancing unit Two tests of the grinders were made: one using an unbalance disc and the other by real grinding. The unbalance disc test was made with a disc of new design, with the shape of a depressed cent
29、re wheel. One reference disc was sent together with the grinding machines, while the other was locally manufactured by the measuring lab. Grinding was made on mild steel with locally purchased grinding wheels. Detailed test instructions were distributed to the participants before the start of the ro
30、und-robin test. 2 Symbols and abbreviated terms See Table 2. ISO/TR 27609:2007(E) 2 ISO 2007 All rights reservedTable 2 Symbols, abbreviated terms and their units Symbols and abbreviations aDescription Unit a hvVibration total value of frequency-massed r.m.s acceleration: root sum of squares of the
31、a hwvalues for the three axes of vibration m/s 2a hArithmetic mean value of measurement results of runs and operators: result of test m/s 2C V,opCoefficient of variation for test based on ratio of standard deviation for operators(s op ) and total mean value for all laboratories C V,RCoefficient of v
32、ariation of reproducibility for test based on ratio of standard deviation for laboratories(s R ) and total mean value for all laboratories G Grinding L 17 Laboratory making the measurement LD Locally made unbalance disc M1 125 mm grinder without auto-balancing unit, pneumatically powered M2 125 mm g
33、rinder with auto-balancing unit, electrically powered M3 230 mm grinder without auto-balancing unit, electrically powered M4 230 mm grinder with auto-balancing unit, pneumatically powered NL No-load RD Reference unbalance disc s opStandard deviation for operator, adjusted for the mean value of each
34、laboratory: () op , 1 1 ij i ij s aa n = , ij a value for operator j at laboratory i i a mean value for laboratory i m/s 2s RStandard deviation of reproducibility for laboratories according to EN 12096:1997, A.10: () 2 R 1 1 1 n i i aa n s = = i a results achieved at n different laboratories a mean
35、value for all laboratories m/s 2aOther symbols and abbreviated terms are according to ISO 20643:2005. ISO/TR 27609:2007(E) ISO 2007 All rights reserved 3 3 Method The round-robin test was evaluated by studying the statistics of the data collected from the different tests and labs using the following
36、 parameters. Spread between operators This parameter gives a measure of the expected spread on laboratory level for the methods. Spread between laboratories This parameter gives the total spread of the method. It includes the spread from operators, machines and measuring equipment. Repeatability Thi
37、s parameter gives the stability of the method. Correlation between grinding and no-load vibration This parameter indicates in what extent grinding vibrations is dominated by unbalance or not. In order to be able to compare values from the different sizes and types of grinder, the coefficient of vari
38、ation the mean value divided by standard deviation was used. Significance tests were made using a double sided t-test with 95 % significance. 4 Description of two test methods evaluated 4.1 Unbalance disc test method The new test wheel had tighter tolerances, thereby reducing the spread in unbalance
39、 from 2 % to 0,5 %. It had a movable unbalance screw instead of a drilled hole, making it possible to vary the unbalance without remounting the disc, and consequently simplifying the measurements and eliminating the uncertainty introduced by loosening of the disc. The disc was shaped as a depressed
40、centre wheel, see Figure 1. Each lab measured the vibrations using two test wheels: one reference test wheel circulated through all test labs (RD) and one manufactured by the measuring lab (LD). A feed force equal to that recommended by ISO 8662-4:1994 was applied to the grinder during the test. Fig
41、ure 1 Sketch of unbalance test disc (unbalance screw enlarged) ISO/TR 27609:2007(E) 4 ISO 2007 All rights reserved4.2 Grinding test method The grinding test was made on mild steel using depressed centre wheels (type 27). Each test session started with a 10 s no-load measurement followed by 1 min of
42、grinding and ending with a 10 s no-load measurement. The mean value of the no-load measurements was taken as the estimated unbalance contribution to the vibration during grinding. An example test measurement set-up is shown in Figure 2. For each grinder, five grinding wheels were used, each operator
43、 grinding once with each wheel. According to the test instructions (see Annex A), the grinding was made at the grinders maximum power by maximizing the amount of sparks from the grinding process. The manner in which this was done differed from lab to lab. Photo: Health and Safety Laboratory, UK Figu
44、re 2 Example of test set-up for grinding test 5 Results 5.1 General During the round-robin test, the reference unbalance disc and screws were damaged, and thus could not actually be used as the reference. However, in some cases they are reported separately. On the M1 grinder, the hose was replaced b
45、y a quick coupling during the round-robin test. As a consequence, the inertia and mass of the machine were changed, possibly affecting the vibration level. However, no difference was detected that can be related to this change. In some cases, large brackets were mounted at the support handle for att
46、aching the feed force wire, thereby also changing the inertia and mass of the machine. As with the case of quick coupling, no signs of differences have been found that can be attributed to this change. ISO/TR 27609:2007(E) ISO 2007 All rights reserved 5 Grinder M1 has a resonant support handle, maki
47、ng the grinder very sensitive to unbalance forces and damping from the operators hand. Grip forces were therefore an important, but not recorded, parameter for the vibration value from this grinder. 5.2 Spread of methods The spread gives an indication of the repeatability and reproducibility of the
48、test methods. The results are presented in the following tables. 5.2.1 Unbalance disc test The results from the unbalance disc test are separately presented for LD and RD, even though RD was changed during the test round and cannot be used as reference disc. The result for both discs is presented in
49、 the “Total” row. See Tables 3 and 4. Table 3 Emission values and standard deviations Unbalance disc test Max. handle Support handle Throttle handle a hs ops Ra hs ops Ra hs ops Rm/s 2m/s 2m/s 2m/s 2m/s 2m/s 2m/s 2m/s 2m/s 2LD 14,33 2,65 3,75 14,33 2,65 3,75 7,34 0,33 1,05 RD 14,68 2,88 4,59 14,68 2,88 4,59 7,16 0,37 0,81 M1 Total 14,40 2,58 3,98 14,40 2,59 3,98 7,29 0,30 1,06 LD 7,58 0,47 1,84 5,10 0,58 0,64 7,58 0,47 1,84 RD 6,99 0,59 1,44 4,78 0,62 0,97 6,99 0,59
