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1、BRITISH STANDARD BS 6916-8: 1988 ISO 7505:1986 Chain saws Part 8: Method of measurement of hand-transmitted vibration ISO title: Forestry machinery Chain saws Measurement of hand-transmitted vibration UDC 674.053:621.93:621.932.5:621.936.6:620.115 + 620.178.5 + 057.2 Licensed Copy: sheffieldun sheff
2、ieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 This British Standard, having been prepared under the direction of the Agricultural Machinery and Implements Standards Committee, was published under the authority of the Board of BSI and comes into effect on 3
3、0 December 1988 BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference AGE/29 Draft for comment 83/76396 DC ISBN 0 580 16327 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Agricultural Machin
4、ery and Implements Standards Committee (AGE/-) to Technical Committee AGE/29, upon which the following bodies were represented: Arboricultural Association British Agricultural and Garden Machinery Association Ltd. Consumer Policy Committee of BSI Consumers Association Department of Trade and Industr
5、y (Consumer Safety Unit, CA Division) Forestry Commission Health and Safety Executive National Farmers Union National Union of Agricultural and Allied Workers Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2
6、006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 BSI 02-2000i Contents Page Committees responsibleInside front cover National forewordii 1Scope and field of application1 2References1 3Data acquisition and processing1 4Positioning of accelerometers2 5Accuracy of the measuring equipment2 6Rotational fre
7、quency range and measured value2 7Measuring object3 8Hand-held method4 9Test report5 Annex Frequency range and weighting filter6 Figure 1 Weighted acceleration sum2 Figure 2 Accelerometer positions3 Figure 3 Test log shape4 Figure 4 Chain saw position at cutting5 Figure 5 Frequency weighting filter
8、for hand-arm Table 1 Guide bar usable cutting length and width of test log4 Table 2 Presentation of test data5 Table 3 Frequency weighting filter for hand-arm6 Publications referred toInside back cover ah,w() Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolle
9、d Copy, (c) BSI BS 6916-8:1988 ii BSI 02-2000 National foreword This Part of BS 6916 has been prepared under the direction of the Agricultural Machinery and Implements Standards Committee. It is identical with ISO 7505:1986 “Forestry machinery Chain saws Measurement of hand-transmitted vibration” pr
10、epared by Technical Committee ISO/TC 23, Tractors and machinery for agriculture and forestry, of the International Organization for Standardization (ISO). It should be noted that this standard is a product test procedure and is not intended as a method of measurement and evaluation for assessment of
11、 operator exposure or field evaluation of data for which case BS 6842:1987 “Measurement and evaluation of human exposure to vibration transmitted to hand”, is the appropriate standard to use. Other Parts of BS 6916 are as follows: Part 1: Glossary of terms; Part 2: Method for specifying requirements
12、; Part 3: Specification for dimensions of front hand guards; Part 4: Specification for strength of front hand guards; Part 5: Methods of evaluating chain brake performance; Part 6: Method of measurement of airborne noise at the operators position; Part 7: Method of evaluating engine performance incl
13、uding fuel consumption; Part 9: Specification for strength of handles; Part 10: Specification for longitudinal balance; Part 11: Specification for general design, performance, safety and construction requirements for internal combustion engined machines.1) Terminology and conventions. The text of th
14、e International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker
15、. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Part of BS 6916”. The Technical Committee has reviewed the provisions of ISO 5347, ISO 5348
16、 and ISO 5349, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. There are no corresponding British Standards. 1) In preparation. Cross-references International StandardCorresponding British Standard ISO 6531:1982BS 6916 Chain
17、 saws Part 1:1988 Glossary of terms (Identical) IEC 651:1979BS 5969:1981 Specification for sound level meters (Identical) Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 BSI 02-2000iii A British Standard does not purport to in
18、clude 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 from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pag
19、es i to iv, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+
20、00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 BSI 02-20001 1 Scope and field of application This International Standard specifies general methods for data acquisition and proce
21、ssing concerning hand-transmitted vibrations induced by portable chain saws. The methods are valid irrespective of how the chain saw is operated during the test, for example, whether it is hand-held or fitted in a stand, and whether it is cutting a log or not. This International Standard specifies a
22、n operator hand-held procedure for acquisition of vibration data from portable chain saws. NOTE 1The hand-arm system exerts an influence on the hand-transmitted vibration and different hands and grips exert different influences. Therefore, the development of a standardized stand for holding the saw
23、during the measurement is planned. The development of such stands is in progress. NOTE 2The measurements in the three axes shall be made at, or clearly related to, the surface of the hand where the energy enters the body. As the hands of the person are in direct contact with the vibrating surface of
24、 the hand-grip, the transducer should be fastened to the vibrating structure. This International Standard is primarily intended for user and manufacturer purposes. 2 References ISO 5347, Methods of calibration of vibration and shock pickups2). ISO 5348, Mechanical vibration and shock Mechanical moun
25、ting of accelerometers2). ISO 5349, Guidelines for the measurement and the assessment of human exposure to hand-transmitted vibration. ISO 6531, Machinery for forestry Portable chain saws Vocabulary. IEC Publication 651, Sound level meters. 3 Data acquisition and processing 3.1 Weighted acceleration
26、 sum The acceleration in three perpendicular directions (defined in clause 4) shall be picked up by accelerometers and processed to form an overall vibration value, the weighted acceleration sum (), according to Figure 1. Mathematically is the mean square of the root (RMS) of the weighted signals fr
27、om each direction. The weighting filters shall have the characteristics given in ISO 5349. (The definition of the weighting filter is given in the Annex.) NOTE 1can be calculated from frequency spectra of 1/3 octave or 1/1 octave with the weighting factors for the mid-frequencies calculated from ISO
28、 5349. (The 1/3 octave analysis will be the most accurate.) NOTE 2To obtain more detailed information about the vibration level, the evaluation according to ISO 5349 should be carried out. (The 1/3 octave analysis will give the most detailed information.) NOTE 3The three different acceleration direc
29、tions may be measured at different times. 3.2 Weight of accelerometers The total mass of the accelerometer(s) giving the acceleration at one measuring position shall not exceed 50 g including the mounting but excluding the cables. 3.3 Mounting of accelerometers If a resilient coating is being used b
30、etween the hand and the vibrating structure (for example, a cushioned handle), it is permissible to use a suitable mount for the transducer (for example, a thin, suitably formed metal sheet) placed between the hand and the surface of the resilient material. In either case, care shall be taken that t
31、he size, shape and mounting of the transducer or of the special transducer support do not significantly influence the transfer of vibration to the hand. Care shall also be taken when mounting the transducer that the transfer function is flat up to 1 500 Hz for all three directions. NOTE 1The transfe
32、r function can be considered flat if an addition of mass to the accelerometer equal to that of the accelerometer and half that of the mount does not significantly influence . (This additional mass shall be placed between the accelerometer and the stud if it is of metal, or around the accelerometer i
33、f it is of clay or wax.) NOTE 2The proposed method for the case of a resilient coating between the hand and the vibrating structure is not satisfactory for all conditions, particularly in the case of thin cushions mainly affecting the transfer of higher frequencies. In such cases it might be prefera
34、ble to make the measurements with the transducer rigidly attached to the handle or structure and to report separately the type, thickness, physical properties and estimated attenuation achieved by the cushioning material. NOTE 3For general considerations concerning accelerometer mounting see ISO 534
35、8. 2) At present at the stage of draft. ah,w ah,w ah,w ah,w Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 2 BSI 02-2000 4 Positioning of accelerometers The different directions of accelerometers and measuring positions are d
36、efined in Figure 2. The centre of gravity of the accelerometers shall be positioned at a maximum distance of 20 mm from the contour described by taking a section through the handle defined by the lines Z and Y for the rear handle and the lines Z and X for the front handle. (See Figure 2.) If the mea
37、surement of 25 mm in Figure 2 cannot be obtained, the accelerometer shall be placed at the right end of that portion of the handle intended to be grasped. If the measurement of 80 mm in Figure 2 cannot be obtained, the accelerometer shall be placed at the rear end of that portion of the handle inten
38、ded to be grasped. 5 Accuracy of the measuring equipment 5.1 Measuring equipment The accuracy of the measuring equipment excluding accelerometer mounting shall be within 10 % in the frequency range 8 to 1 500 Hz (see ISO 5347 concerning calibration). 5.2 Electric noise Special care shall be taken to
39、 avoid electric noise generated by the saw. (A suppressed spark-plug is recommended.) When the saw is running at the test place with the accelerometers free from contact with the saw but near to it (at a maximum distance of 20 mm from the measuring positions) the electric noise shall not exceed 5 %
40、of the maximum measured value reported. 5.3 Rotational frequency indicator The accuracy of the rotational frequency indicator shall be within 2,5 % of the reading. 6 Rotational frequency range and measured value 6.1 Nominal rotational frequencies The weighted acceleration sums at the front and the r
41、ear handles shall be measured at the following rotational frequencies: a) idling rotational frequency as recommended by the manufacturer (idling); b) rotational frequency at maximum engine power as stated by the manufacturer (full load); c) 133 % of the rotational frequency at maximum engine power o
42、r maximum rotational frequency, whichever is the less (racing). Figure 1 Weighted acceleration sum ()ah,w ah,w() Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 BSI 02-20003 6.2 Measuring interval Each measured value shall be
43、taken as the RMS-value over 2 s (equal to 1 s RC-detector time constant or time weighting characteristic S “slow” according to IEC 651). The rotational frequency shall be kept within 3,5 s1 of the nominal rotational frequency during the registration. 6.3 Reported weighted acceleration sum Each repor
44、ted value of shall be the RMS-value of at least five measured values according to 6.2. 7 Measuring object Measurements shall be carried out on a normal production saw. The engine shall have been run in and warmed up before the test commences, carburettor set and ignition timed according to the instr
45、uctions of the manufacturer. The chain shall be lubricated and the tanks shall be at least half-full. The chain shall be new and shall be adjusted for best cutting performance in accordance with the chain saw manufacturers recommendation. Figure 2 Accelerometer positions ah,w() ah,w Licensed Copy: s
46、heffieldun sheffieldun, na, Tue Dec 05 04:27:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6916-8:1988 4 BSI 02-2000 8 Hand-held method 8.1 Conditions 8.1.1 Measuring conditions The measurements shall be carried out under the conditions described above. 8.1.2 Wood specification For cutting tests
47、a sound, well-grown log shall be taken from freshly-felled hardwood as in normal local usage. The log shall not be frozen. The cut shall be made in a part of the log free from knots. 8.1.3 Test log shape and guide bar length The shape of the log should be as given in Figure 3 and Table 1. The guide
48、bar shall be that supplied by the manufacturer intended for normal use of the saw. If no guide bar is supplied a guide bar according to Table 1 shall be chosen. The width of the log shall be correlated to the usable cutting length (see ISO 6531) of the guide bar in accordance with Table 1. Table 1 G
49、uide bar usable cutting length and width of test log 8.2 Operations 8.2.1 General conditions The chain saw shall be operated upright in accordance with Figure 4. The log shall be horizontal and rigidly mounted on a stiff support, so that its centreline is about 0,6 m above the ground level. A relaxed grip on the handles sufficient to maintain proper control shall be employed, consistent with day-long use of the saw. 8.2.2 Operation sequence The operation sequence shall be idling, cutting (full load),