1、UDC 621.833.2 : 621.753.1 DEUTSCHE NORM August 1986 I l DIN 3965 Tolerancing of bevel gears Basic concepts Part 1 Toleranzen fr Kegelradverzahnungen; Grundlagen Supersedes September 1981 edition. In keeping with current practice in standards published by the International Organization for Standardiz
2、ation (KO), a comma has been used throughout as the decimal marker. Contents Page 1 Field of application . 1 2 Scope . 1 3 Symbols and quantities . 1 Tolerances on gear blank dimensions 2 4 5 Structure of the gear tolerance system . 2 5.1 Relationship between tolerances 2 5.2 Errors and deviations o
3、f parameters 2 1 Field of application This standard specifies tolerances for straight, skew and spiral bevel gears with and without axial offset, of modules 1 mm to 50 mm and with reference diameters up to 2500 mm. 2 Scope To ensure compliance with all the functional requirements to be met by bevel
4、gears, relating to smooth running, load bearing capacity, uniform angular transmission and operating life, it is essential that the errors of certain parameters of the tooth system be kept within given limits. The sizes of the tolerances have been developed on principles similar to those applying to
5、 the tolerancing of circular fits. Thus, as for circular fits, tolerance classes have also been specified to a fineness which cannot be technically realized at present, but which is likely to represent the fineness possible in the future. 3 Symbols and quantities a dimension of tooth contact pattern
6、, axial offset c dimension of tooth contact pattern d reference diameter; dimension of tooth contact pattern dm mean reference diameter dB test flange diameter dR reference surface diameter e f fa axes intersection point error fi tangential tooth-to-tooth composite error dimension of tooth contact p
7、attern individual error; dimension for tooth contact pattern Page 5.3 Tolerance classes for bevel gears .2 5.4 Calculation of tolerances .3 6 Tolerancing .3 7 Additional gauging methods . 3 7.1 Radial run-out . 3 7.2 Pitcherror . .3 7.3 Tangential composite error .3 8 Tooth contact pattern . .4 shor
8、t-wave component of tangential composite error longwave component of tangential composite error adjacent pitch error difference between adjacent pitches shaft angle error module normal module at mean cone distance apex to back distance tip distance auxiliary plane distance gear ratio bore diameter c
9、omposite and cumulative errors working deviation tangential composite error cumulative pitch error radial run-out radial run-out of test flange of diameter dg, relative to gear axis axial run-out of reference face FI, relative to gear axis reference faces K1 to Kg auxiliary quantities Rm mean cone d
10、istance 6 reference cone angle da tip angle for tolerance classes 7 to 9: IT 6; for tolerance classes 10 and upwards: IT 7. 0; 5 Structure of the gear tolerance system 5.1 Relationship between tolerances The tolerance system for bevel gears is similar to that developed for cylindrical gears (see DIN
11、 3961). An attempt has been made to ensure that a particular gear quality roughly covers the average values of all errors and deviations from the target manufacturing quality. However, it frequently happens that differences in requirements and manufacturing processes cause changes in the relationshi
12、p between individual errors (see clause 6). The tolerances given in DIN 3965 Parts 2 to 4 have been specified as far as possible on the basis of existing manufacturing experience. For the single flank working test, tolerances have been given for fi and fk, as alternatives to those given for Fi and f
13、i (see DIN 3965 Part 3). To avoid inconsistency, the tolerances for FI and fi on the one hand, and for fi and fi on the other hand, shall not be applied simul- taneously . 5.2 Errors and deviations of parameters For the purposes of this standard, individual errors, f, are deviations of individual pa
14、rameters of the tooth system (such as pitch) from the desired values, whilst composite and cumulative errors, F, allow for the effect of several individual errors. See DIN 3971 for definitions of parameters. Some of the possible errors or deviations (see DIN 3971 ) cannot be determined with sufficie
15、nt accuracy at the present time. Others, such as radial composite errors should not be used for assessment purposes, since the measurement of these errors has to be carried out under conditions involving a displacement of the tooth contact pattern. The measurement may only be used for deter- mining
16、the radial run-out. 5.3 Tolerance classes for bevel gears The tolerance system for bevel gears as specified in this standard covers 12 tolerance classes. In present-day manufacturing practice it is not possible to achieve the finer tolerance classes. They are included only for the DIN 3965 Part 1 Pa
17、ge 3 sake of completeness. The tolerances are multiplied by an increment,q, at each step. Values of (p are given in subclause 5.4. The limit values of the referencediameter and normal module ranges have been taken from the R 20 preferred number series specified in DIN 323 Part I. 5.4 Calculation of
18、tolerances Formulae are stated below for calculating the tolerances for which numerical values have been given in DIN 3965 Parts 2 and 3, taking tolerance class 4 as the basis. Values of mmn and d, are given in mm, tolerances, in pm. The reference circle and normal module are each related to the mea
19、n reference cone distance. When calculating the tolerances from the formulae, the geometrical means of the corresponding range limits shall be substituted for the actual values of mmn and d,. For figures smaller than 10, the tolerances so calculated shall be rounded to the nearest value that gives a
20、n integer when divided by 0,5, whilst figures greater than 10 shall be rounded to the nearest integer. a) Adjacent pitch error: f, = 4 + 0,315 (mmn + 0,25 Ild,) with (p = 1,4 up to tolerance class 8 and (P = 1,6 from tolerance class 8. b) Difference between adjacent pitches: f, = 5 + 0,4 (mmn + 0.25
21、 lid,) with (p = 1,4 up to tolerance class 8 and p = 1.6 from tolerance class 8. c) Cumulative pitch error: Fp = 7,25 . mmi . basic values, calculated values, rounded values Tolerances for cylindrical gear teeth; bases Tolerancing of bevel gears; tolerances for individual parameters Tolerancing of b
22、evel gears; tolerances for composite and cumulative errors Tolerancing of bevel gears; tolerances for shaft angle errors and axes intersection point deviation Terminology and parameters for bevel gears and bevel gear pairs DIN 3965 Part 1 : 09.81. The following amendments have been made in compariso
23、n with the September 1981 edition. a) The status of the standard is no longer that of a preliminary standard. b) The symbols denoting the components of the tangential composite errors, fP and FP, have been altered to f;, and fi c) The standard has been editorially revised. respectively. Explanatory
24、notes DIN 3965 Parts 1 to 4 only provide information on the gear blank and on errors that can be measured by conventional means. The finer tolerances cannot yet be measured under production conditions. Nevertheless, the tables shown in DIN 3965 Parts 2 and 3 cover all diameter ranges, the fields cro
25、ssed out indicating that for these diameter ranges no tolerances can currently be specified. In future, more advanced gauging and calculation methods may allow errors to be dealt with, which have not as yet been specified, such as profile errors, and more information to be provided regarding the acc
26、uracy of bevel gears. The parameters (see clause 3) have been defined in DIN 3971, the aim of which was to include as many quantities as possible without regard for the carrent feasibility or difficulty of their measurement. The structure of the tolerance system for bevel gears has been brought into
27、 line with that for cylindrical gears. The relationship between the parameters are the same, except for an overall shift in the tolerance system by one tolerance class. The tolerance system proposed may thus serve as an adequate basis for international discussion. International Patent Classification F 16 H 55/08 F 16 H 55/17 2) This is caused by the generally periodic behaviour of the long-wave component of the tangential composite error associated with one revolution of the gear.
