ISO-484-1-1981.pdf
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1、International Standard 48411 INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONWlEIK,QYHAPOAHAR OPl-AHM3AUMR fl0 CTAHAAPTkl3AMM.ORGANISATION INTERNATIONALE DE the indications in table 1 serve as guide in this choice. lt could be a line joining the nose and tail of the section but may be any other conven
2、iently placed helical line. Table 1 7.6 The local pitch at a Point B (figure 1) is determined by measuring the differente in height between two Points P and 0 situated at equal distances from Point B and on either side of the latter (BP = BQ) and by multiplying the differente in 360 height by . This
3、 shall be compared with the local pitch as a calculated from the face offsets for the same Points. I Class I Manufacturing accuracy I Very high accuracy High accuracy Medium accuracy Wide tolerantes The distance between any two Points used for a local pitch measurement may range between 100 mm and 4
4、00 mm. One pitch measurement is to be near the leading edge, one near the trailing edge and there shall be at least two other pitch measurements in between. As far as possible the pitch measurements should be consecutive. 7 Tolerantes on the pitch Table 2 r Class Designation of pitch S I II Ill 7.7
5、The pitch per radius and per blade is determined for each radius by multiplying the differente in height between the 360 extreme measuring Points by - . a each radius of c) Mean pitch per Ib 1,5% I!I 2 % It:3% - + 1 % f 1,5% f: 2 % AI 5 % I!I 0,75 % f 1 % + 1,5% I!I 4 % 7.8 The mean pitch per blade
6、is defined as the arithmetic mean of the pitches per radius for the blade in question. I . I I I I I 7.9 The mean pitch for the screw Propeller is defined as the arithmetic mean of the mean pitches per blade. NOTE - The tolerantes of table 2 are expressed as percentages of the design pitch correspon
7、ding to the radius for designations a) and b) and the mean design pitch for designations c) and d). 8 Tolerantes on the extreme radius of the screw Propeller 7.1 Pitch shall be measured at least at the radii indicated in table 3 below. By agreement between the interested Parties dif- ferent radii ma
8、y be measured. 8.1 The tolerantes in table 4 are expressed as percentages of screw Propeller radius. Table 3 Table 4 1 Class 1 Radii I I Class Specification s 1 I 1 II 1 Ill S and I A section near the hub - 0,4 R - 0,5 R - 0,6 R - 0,7R - 0,8 R - 0,9R - 0,95R Ct II A section near the hub - 0,5 R - 0,
9、6 R - 0,7 R - 0,8 R - 0,9 R Ill A section near the hub - 0,5 R - 0,7 R - 0,9 R 1 Tolerante I Ik 0,2 % 1 It 0,3 % 1 AI 0,4 % 1 AI 0,5 % 1 8.2 In the case of a ducted Propeller, these tolerantes may be need to be reduced. 3 -,-,- ISO 484/1-1981 (EI 9 Tolerantes on the thickness of the blade section Ta
10、ble 5 Class Specification S I II Ill Plus tolerantes + 2 % + 2,5 % + 4 % + 6 % With a minimum of 2 mm 2,5 mm 4mm 6mm Minus tolerantes -1% - 1,5% - 2 % -4% With a minimum of - lmm - 1,5mm -2mm -4mm 9.1 The thickness shall be measured at the same radii as those at which the pitch is measured. 9.2 The
11、tolerantes in table 5 are expressed as percentages of the local thickness. 9.3 The maximum thicknesses indicated on the drawing shall not be less, after deduction of the minus tolerante, than the thicknesses required by the Classification Society con- cerned. 10 Checking and tolerantes of the form o
12、f blade sections These apply only to propellers of class S and I and to the same radii as those at which the pitch is measu red. To avoid discontinuity of form, the deviations resulting from consecutive measurements of local pitch and thickness shall Propeller class I On the figure the deviations ar
13、e multiplied by 20 The values which are too high are underlined Deviation in local pitch Differente Sum not differ from each other by more than half the tolerante envelope (for example if the tolerante is + 2 % 1 - 2 %, the permitted differente of consecutive deviations is 2 %.) To avoid undue devia
14、tion in Overall camber, the algebraic sum of the percentage deviations resulting from any two consecutive measurements of local pitch shall not be in ex- cess of 1,5 times the allowable tolerante (for example if the tolerante is I!Z 2 %, the sum of consecutive deviations shall lie between + 3 %. See
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