1、Synchronous belts Calculation of power rating and drive centre distanceBS ISO 5295:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06 ISO 2017Synchronous belts Calculation of power rating and drive centre distanceCourroies synchrones Calcul de la puissance transmis
2、sible et de lentraxeINTERNATIONAL STANDARDISO5295Third edition2017-04Reference numberISO 5295:2017(E)National forewordThis British Standard is the UK implementation of ISO 5295:2017.The UK participation in its preparation was entrusted to Technical Committee MCE/10, Belts the belt width; the mass of
3、 a linear metre of belt; the allowable working tension in the belt; the angular velocity of the smaller pulley; the number of teeth of the smaller pulley; the number of teeth in mesh on the smaller pulley. ISO 2017 All rights reserved 1BS ISO 5295:2017ISO 5295:2017(E)4 SymbolsSymbol Description Unit
4、sPbpitch of the teeth of the belt and pulleys mmbswidth of the belt to be rated mmbsobase width of the widest standard belt of pitch Pb(see Table 2) mmm linear mass of a belt having a width bsokg/mTaallowable working tension of a belt having a width bsoNw angular velocity of the smaller pulley rad/s
5、v belt velocity m/sz1number of teeth of the smaller pulleyz2number of teeth of the larger pulleyzbnumber of teeth of the beltZmnumber of teeth in mesh on the smaller pulleyc centre distance of the pulleys mmPopower rating of a belt of base width bsokWP power rating of a belt of base width bskWkwwidt
6、h factorkzteeth in mesh factorent integer part only of the expression following5 Basic power ratingThe basic power rating of a belt of base width, bso, is given by the Formula (1):PTmvvoa=( )21000(1)where the belt velocity, v, has the value given by Formula (2):vPz=b13102pi(2)Formula (1) is valid on
7、ly if the number of teeth in mesh zm 6 (see Clause 6 for zm 6).The values of Taand m depend upon the construction and the type of belt; these shall be supplied by the belt manufacturer.6 Power rating6.1 Exact formulaThe power rating of a belt of width, bs, having zmteeth in mesh on the smaller pulle
8、y, is given by Formula (3):PkkTbmvbv=zwasso2310 (3)See Clauses 9 and 10 for kzand kw, respectively.2 ISO 2017 All rights reservedBS ISO 5295:2017ISO 5295:2017(E)4 SymbolsSymbol Description UnitsPbpitch of the teeth of the belt and pulleys mmbswidth of the belt to be rated mmbsobase width of the wide
9、st standard belt of pitch Pb(see Table 2) mmm linear mass of a belt having a width bsokg/mTaallowable working tension of a belt having a width bsoNw angular velocity of the smaller pulley rad/sv belt velocity m/sz1number of teeth of the smaller pulleyz2number of teeth of the larger pulleyzbnumber of
10、 teeth of the beltZmnumber of teeth in mesh on the smaller pulleyc centre distance of the pulleys mmPopower rating of a belt of base width bsokWP power rating of a belt of base width bskWkwwidth factorkzteeth in mesh factorent integer part only of the expression following5 Basic power ratingThe basi
11、c power rating of a belt of base width, bso, is given by the Formula (1):PTmvvoa=( )21000(1)where the belt velocity, v, has the value given by Formula (2):vPz=b13102pi(2)Formula (1) is valid only if the number of teeth in mesh zm 6 (see Clause 6 for zm 6).The values of Taand m depend upon the constr
12、uction and the type of belt; these shall be supplied by the belt manufacturer.6 Power rating6.1 Exact formulaThe power rating of a belt of width, bs, having zmteeth in mesh on the smaller pulley, is given by Formula (3):PkkTbmvbv=zwasso2310 (3)See Clauses 9 and 10 for kzand kw, respectively.2 ISO 20
13、17 All rights reserved ISO 5295:2017(E)6.2 Approximate formulaThe power rating may be calculated approximately by simplification of Formula (3) as given by Formula (4):P kzkwPo(4)7 Centre distance7.1 Exact formulaFirst, calculate the auxiliary angle, , using Formula (5): =pizzzzb221(5)where inv = ta
14、n ; the value of (see Figure 1) can be determined by iteration or from involute tables.The centre distance, C, is then given by Formula (6):CPz z=()bcos212pi (6)The method according to Formula (5) and (6) is valid in any case. However, it should not be used if the ratio z2/z1is close to unity, becau
15、se the expression for C becomes the ratio of two small quantities. In this case, the method according to 7.2 is recommended.Key1 C 3 Z1teeth2 4 Z2teeth5 ZbteethFigure 1 Centre distance ISO 2017 All rights reserved 3BS ISO 5295:2017ISO 5295:2017(E)7.2 Approximate formulaFirstly, calculate M by Formul
16、a (7)MPzzz=()bb8212(7)then the centre distance, C, by Formula (8):CM MPz z=+ ()221218bpi(8)This method is to be avoided when the ratio z2/z1is large. In this case, the method according to 7.1 shall be used.8 Number of teeth in meshThis number is given by Formula (9):zz PzCzzmbent= ()1 122122pi(9)in
17、which 122pimay be replaced by 120for ease of calculation.9 Factor kzThe factor kzis given by Formulae (10) and (11):If zm 6, kz= 1 (10)If zm 6, kz= 1 0,2(6 zm) (11)10 Factor kwThe factor kwis given by Formula (12):kbbwsso=114,(12)where bsodepends upon the pitch code as given in Table 1.The resulting
18、 calculation of kwis rounded off to two decimal places according to the usual convention.4 ISO 2017 All rights reservedBS ISO 5295:2017ISO 5295:2017(E)7.2 Approximate formulaFirstly, calculate M by Formula (7)MPzzz=()bb8212(7)then the centre distance, C, by Formula (8):CM MPz z=+ ()221218bpi(8)This
19、method is to be avoided when the ratio z2/z1is large. In this case, the method according to 7.1 shall be used.8 Number of teeth in meshThis number is given by Formula (9):zz PzCzzmbent= ()1 122122pi(9)in which 122pimay be replaced by 120for ease of calculation.9 Factor kzThe factor kzis given by For
20、mulae (10) and (11):If zm 6, kz= 1 (10)If zm 6, kz= 1 0,2(6 zm) (11)10 Factor kwThe factor kwis given by Formula (12):kbbwsso=114,(12)where bsodepends upon the pitch code as given in Table 1.The resulting calculation of kwis rounded off to two decimal places according to the usual convention.4 ISO 2
21、017 All rights reserved ISO 5295:2017(E)Table 1 Base widthsDimensions in millimetresPitch code bsoMXL6,4XXLXL 9,5L 25,4H 76,2XH 101,6XXH 127 ISO 2017 All rights reserved 5BS ISO 5295:2017This page deliberately left blankThis page deliberately left blankBSI is the national body responsible for prepar
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