1、DEUTSCHE NORM November 1997 General-purpose knuckle threads Part 2: Tolerances DIN 405-2 - ICs 21.040.30 This standard supersedes the October 1981 edition of DIN 405-2 and, together with DIN 405-1, November 1997 edition, the November 1975 edition of DIN 405-1. Rundgewinde allgemeiner Anwendung - Tei
2、l 2: Abmae und Toleranzen In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker. Foreword This standard has been prepared by the Normenausschu Technische Grundlagen (Fundamentals in
3、Tech- nology Standards Committee), Technical Committee Toleranzen. Amendments The following amendments have been made to the October 1981 edition and DIN 405-1, November 1975 edition. a) For the major diameter of external threads, tolerance classes 6e and 7e have been introduced. b) For the minor di
4、ameter of external threads, tolerance classes 7h, 7e, 8h and 8e have been introduced. c) Some symbols have been changed. d) The standard has been editorially revised. Previo us edit ions DIN 405: 1922-04, 1928-04, 1953-01; DIN 405-1 : 1975-1 1 DIN 405-2 : 1981 -1 O. Dimensions in mm 1 Scope and fiel
5、d of application This standard specifies a tolerance system for general-purpose knuckle threads with profiles as specified in DIN 405-1. See DIN 405-1 for thread profiles and nominal sizes and DIN 405-3 for gauges for external and internal threads. Continued on pages 2 to 9. Translation by DI N-Spra
6、chendienst. In case of doubt, the German-language original should be consulted as the authoritative text. No pari of this translation may be reproduced without the prior permission of Ref. No. DIN 405-2 : 1997-1 V Deutsches Institut fr Nonung e. V., Berlin. Luth Verlag GmbH, D-10772 Berlin, has the
7、exclusive right of sale for German Standards (DIN-Normen). English price group 07 Sales No. 0107 12.98 Page 2 DIN 405-2 : 1997-1 1 2 Normative references This standard incorporates, by dated or undated reference, provisions from other publications. These norma- tive references are cited at the appro
8、priate places in the text and titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publicat
9、ion referred to applies. DIN 323-1 Preferred numbers and preferred number series - Basic, calculated and rounded values DIN 405-1 General-purpose knuckle threads - Profiles and nominal sizes DIN 405-3 General-purpose knuckle threads - Gauges for external and internal threads -Types, profiles and tol
10、erances DIN 2244 Screw threads - Terminology 3 Concepts and symbols For the purposes of this standard, the concepts specified in DIN 2244 shall apply. For symbols, see DIN 405-1 and DIN 405-3. 4 Designation 4.1 General A complete designation for a screw thread includes the basic designation, the thr
11、ead size and pitch (number of threads per 25,4 mm), and an identification for the tolerance classes. To this may be appended other supplementary symbols, when and as applicable. Where the tolerance class is not indicated, it shall be taken to be 7H/6H for internal threads and 7h/6h for external thre
12、ads. 4.2 Designation for single-start threads General-purpose knuckle threads (.e. single-start threads) having a profile as specified in DIN 405-1 shall be designated by the letters Rd, the nominal size, in mm, and the pitch, as shown in the example below. EXAMPLE 1 : Rd 40 X 1/6 The designation sh
13、all also include the pitch diametertolerance, followed by the tolerance on the minor diameter (internal threads) or the major diameter (external threads). If both tolerances are the same, the symbol need only be given once. NOTE: Since clause 1 O recommends different tolerances for the pitch diamete
14、r and major or minor diameter, The symbol for the tolerance class shall consist of a numeral indicating the tolerance grade and a letter indicating the tolerance position (a capital letter for internal threads, a lower-case letter for external threads). EXAMPLE 2: External thread both must be given
15、in the designation. Rd 40 X 1/6 - 7h Single-start knuckle thread with a thread diameter of 40 mm and a 1/6 pitch Tolerance class for pitch diameter Tolerance class for external diameter Rd 40 X 1/6 - 7h Single-start knuckle thread with a thread diameter of 40 mm and a 1/6 pitch Tolerance class and m
16、ajor diameter) Page 3 DIN 405-2 : 1997-1 1 Internal thread Rd 40 X 1/6 - 7H 6H Single-start knuckle thread with a thread Tolerance class for minor diameter diameter of 40 mm and a 1/6 pitch Tolerance class for pitch diameter Rd 40 X 1/6 - 7H Single-start knuckle thread with a thread diameter of 40 m
17、m and a 1/6 pitch Tolerance class (when identical for pitch diameter and minor diameter) A fit between a pair of threaded parts is to be designated by indicating the internal thread tolerance class, followed by the external thread class, the two being separated by a stroke. EXAMPLE 3: Rd 40 X 1/6 -
18、7H 6H/7h 6h Rd 40 X 1/6 - 7H/7h The letter L shall be used to designate a group L (long) thread of engagement and shall be preceded by a dash. EXAMPLE 4: Rd 40 X 1/6-7h 6h - L The absence of the indication of the group of thread engagement means that the group of thread engagement N (normal) is spec
19、ified. 4.3 Designation for multi-start threads Multi-start knuckle threads as specified in DIN 405-1 shall be designated by the letters Rd, the nominal size, in mm, the lead of the thread, letter P, and the pitch, as shown in the example below. EXAMPLE (for a double-start thread): Rd 40 X 1/3 P 1/6
20、Lead, Ph 1/3 Pitch. P 1/6 - Number of threads, n = - 4.4 Designation for left-hand threads A left-hand thread shall be designated by the letters LH, which shall be preceded by a dash. EXAMPLES: Rd 40 X 1/6 - LH Rd40X1/6-7H6H-L-LH Rd40X 1/3P1/6-7h6h L-LH Page 4 DIN 405-2 : 1997-1 1 Thread diameter DI
21、 d d3 D, d, 5 Tolerance grades Tolerance grades shall be as specified in table 1 Tolerance grade 6or7 6or7 7 or8 7 or8 69, 7 or 8 e es - 78 - 85 - 97 -1 20 6 Tolerance positions The tolerance positions shall be as follows: for internal threads: H, with fundamental deviation EI = O; for external thre
22、ads: h, with fundamental deviation es = O; e, with negative fundamental deviation. h es O O O O Table 2: Fundamental deviations es and EI Pitch, P 2,54 3,175 4,233 6,35 Fundamental deviations, in pm Internal thread diameters D, and D, H EI I line (nominal size) Figure 1: Internal thread with fundame
23、ntal deviation EI = O (tolerance position H) Page 5 DIN 405-2 : 1997-1 1 N From To 9 25 12 35 13 39 20 59 22 67 36 107 39 116 Zero line (nominal size) -Er- L Over 25 35 39 59 67 107 116 h Figure 2: External thread with fundamental deviation es = O (tolerance position h) Nominal profile Zero line (no
24、minal size) Figure 3: External thread with a negative fundamental deviation es (tolerance position e) 7 Lengths of thread engagement The length of thread engagement may be normal (group N) or long (group L). Table 3: Lengths of thread engagement Nominal thread diameter, d, in mm 38 72 72 1 O0 1 O0 1
25、50 150 200 Pitch, P, in mm 2,54 3,175 3,175 4,233 4,233 6,35 6,35 Page 6 DIN 405-2 : 1997-1 1 Pitch, P, in mm 2,54 3,175 4,233 6,35 8 Tolerances on minor and major diameters 8.1 Minor diameter tolerances for internal threads, T, T, in pm, for tolerance grade 6 7 450 560 530 670 630 800 850 1060 Pitc
26、h, P, in mm 2,54 3,175 4,233 6,35 8.2 Tolerances on major diameter of internal threads No tolerances are specified. Td, in pm, for tolerance grade 6 7 335 425 375 475 475 600 630 800 8.3 Major diameter tolerances for external threads, Td Table 5: Tolerances Td Nominal thread diameter, d, in mm Over
27、up to 7 12 12 38 38 1 O0 1 O0 200 Td3 in pm, Pitch, P, for tolerance grade 8 in mm 7 2,54 250 31 5 3,175 300 375 4,233 375 475 6,35 500 63 O 8.4 Tolerances on minor diameter of external threads, Td3 Table 6: Tolerances Td3 Over 7 12 38 1 O0 up to 12 38 1 O0 200 9 Tolerances on pitch diameter 9.1 Tol
28、erances on pitch diameter of internal thread, TD2 Table 7: Tolerances TD2 I Pitch, P, in mm 2,54 3,175 4,233 6.35 for tolerance grade jj7j-j 500 Page 7 DIN 405-2 : 1997-1 1 6H 9.2 Tolerances on pitch diameter of external thread, Td2 Table 8: Tolerances Ta 7H Nominal thread diameter, d, in mm 38 1 O0
29、 1 O0 200 N Pitch, P, in mm 3,175 4,233 L Td2, in pm, for tolerance grade 236 236 300 375 31 5 400 500 1 O Recommended tolerances To reduce the number of gauges and tools needed in practice, the tolerances specified in tables 9 to 12 should be used. Thread engagement group N is recommended unless ot
30、herwise specified. To avoid confusion, tools and gauges shall bear the full designation, including the tolerance class. 10.1 Recommended tolerance classes for pitch diameter 0, of the internal thread Table 9: Recommended tolerance classes for D, Tolerance class for pitch diameter for thread engageme
31、nt group N L 7H 8H 10.2 Recommended tolerance classes for minor diameter 0, Table 1 O: Recommended tolerance classes for D, Tolerance class for minor diameter for thread engagement group N I L 10.3 Tolerance classes for pitch diameter d, Table 11 : Tolerance classes for d, Tolerance class for pitch
32、diameter for thread engagement group 7h 8h I 7e I 8e Page 8 DIN 405-2 : 1997-1 1 N 10.4 Tolerance classes for major diameter d Table 12: Tolerance classes for d L Tolerance class for major diameter for thread engagement group N L 6h Thread engagement groups N L 7h Lengths of thread engagement 2,24 P
33、. do2 to 6,7 P. do2 Over 6,7 P . do2 6e 7e 10.5 Tolerance classes for minor diameter d, Table 13: Tolerance classes for d, Tolerance class for minor diameter for thread engagement group 7h 8h 7e 8e 11 Formulae 11 .I The lengths of thread engagement are to be calculated from table 14. Lengths of thre
34、ad engagement Table 14: Formulae for calculating lengths of thread engagement d is the smallest diameter within the diameter range given in table 3. 11.2 Tolerances on minor diameters 11.2.1 Tolerances have been calculated from equation (l), as follows: Tolerances on minor diameter of internal threa
35、d, T, (grade 6) T, (6) = 230 (1 1 with T, in pm and P in mm. T, tolerances of grade 7 can be obtained by multiplying the values for grade 6 tolerances by a factor of 1,25. 11.2.2 Tolerances on minor diameter of external threads, Td3 Tolerances have been calculated from equation 2, as follows: Td3 =
36、1,25 . Ta with Td2 and Td3 in pm (values for Td2 from table 8). 11.3 Tolerances on the major diameter of external threads, Td (grade 6) Tolerances have been calculated from equation (3), as follows: Td(6) = 180w - 3,15 with Td in pm and P in mm. Jp (3) Page 9 DIN 405-2 : 1997-1 1 Tolerance grade Fac
37、tor 7 8 1,25 1,6 Tolerance grade 7 8 11.5 Fundamental deviation es The fundamental deviation es for tolerance position e is to be calculated from equation 5, as follows: es (e) = -(50 + 11 P) pm (5) with P in mm. Factor 11.6 Rounding of figures The tolerances on the major, pitch and minor diameters
38、have been calculated from equations (1) to (4) and then rounded to the nearest values of the R 40 series of preferred numbers specified in DIN 323-1. 1,7 2,12 12 Multi-start threads When calculating the length of thread engagement for multi-start threads, the lead, Ph, shall be substituted for pitch
39、, P, in the formulae given in table 14. The equations specified for single-start threads shall be used to calculate T,(6), T,(6), Td2(6) and T,(6) toler- ances and the fundamental deviation es for multi-start threads, except that the values specified in table 2 of DIN 405-1 are to be taken for P. Number of threads, y1 Factor Table 17: Multiplication factors for multi-start threads 1 2 3 4 5 and over 1 1,12 1,25 1,4 1,6 Example of calculating a grade 7 TD2 tolerance for a three-start internal thread: TD2 (7) = Td2 (6) . 1,7 . 1,25.
