1、AN AMERICAN NATIONAL STANDARDScrew Threads: Nomenclature, Definitions, and Letter Symbols ASME B1.7-2006(Revision of ANSI/ASME B1.7M-1984)Intentionally left blank ASME B1.7-2006(Revision of ANSI/ASME B1.7M-1984)Screw Threads:Nomenclature,Definitions, andLetter SymbolsThree Park Avenue New York, NY 1
2、0016AN AMERICAN NATIONAL STANDARDDate of Issuance: November 17, 2006This Standard will be revised when the Society approves the issuance of a new edition. There will beno addenda or written interpretations of the requirements of this Standard issued to this edition.ASME is the registered trademark o
3、f The American Society of Mechanical Engineers.This code or standard was developed under the procedures accredited as meeting the criteria for American NationalStandards. The Standards Committee that approved the code or standard was balanced to assure that individuals fromcompetent and concerned in
4、terests have had an opportunity to participate. The proposed code or standard was madeavailable for public review and comment, which provides an opportunity for additional public input from industry, aca-demia, regulatory agencies, and the public-at-large.ASME does not “approve”, “rate,” or “endorse
5、” any item, construction, proprietary device, or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with any itemsmentioned in this document, and does not undertake to insure anyone utilizing a standard against liability for infringe-men
6、t of any applicable letters patent, nor assumes any such liability. Users of a code or standard are expressly advisedthat determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely theirown responsibility.Participation by federal agency represen
7、tative(s) or person(s) affiliated with industry is not to be interpreted as gov-ernment or industry endorsement of this code or standard.ASME accepts responsibility for only those interpretations of this document issued in accordance with the establishedASME procedures and policies, which precludes
8、the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue, New York, NY 10016-5990Copyright 2
9、006byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vCommittee Roster . . . . . . . . . . . . . . . . . . . . . . . . . .
10、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Definition of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11、 . . . . . . . . . . . . . 1Figures1 Allowance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Axis of Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
12、Best Wire Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 Blunt Start Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Bottom of Chamfer . . . . . . . . . . . .
13、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Clearance Flank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Countersink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、 . . . . . . . . . . . . . . . . . . . . .48 Crest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Root and Crest Truncation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、. 510 Fundamental Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 Metric Tolerance System for Screw Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 712 Element . . . . . . . . . . . . . . . . . . . . . . . . .
16、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713 Flank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 714 Flank Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . .715 Flat Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716 Following Flank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . 817 Gauge Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .818 Height of Fundamental Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 819 Height of Thread . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 920 Height of Thread Engagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 921 Helix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . . . . . . . . . . . . . . . . . . 922 Helix Variation (Drunken Thread) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 923 Incomplete Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024 Inte
21、rference Fit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1125 Internal Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1126 Lead . . . . . . . . . . . . . . . .
22、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1127 Leading Flank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1128 Gaging Length . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1129 Length of Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1130 Length of Thread Engagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . 1231 Load Flank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1232 Major Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1233 Major Diameter, Exter
25、nal Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1234 Major Diameter, Internal Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1235 Major Diameter, Internal Thread (Rounded Form) . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . 1236 Major Diameter, Taper Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237 Minor Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1338 Minor Diameter, Ex
27、ternal Thread (Flat Form) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1439 Minor Diameter, External Thread (Rounded Form) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1440 Minor Diameter, Internal Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . 1441 Minor Diameter, Taper Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1442 Multiple Start Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14iii43 Pitch . . . . . . . . .
29、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1444 Pitch Cone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1445 Pitch Cylinder . . . . . . . . . . . . . . . . . .
30、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1446 Pitch Diameter, External Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1547 Pitch Diameter, Internal Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31、. . . . . . . . . . 1548 Plane of Vanish Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1549 Profile, Basic Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1650 Root Radius . .
32、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1651 Screw Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1652 Sharp Crest and Root . . . . . . . . . . . . . . .
33、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1653 Shear Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1754 Straight Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34、. . . . . . . . . . . . . . . . . . . . 1855 Thread Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2356 Thread Ridge Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
35、57 Truncation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2358 Vanish Cone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Tables1 General Symbols . . . . .
36、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 ISO General Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Thread Series Designations . . . . . . . . . . . . . . . . . . . . .
37、. . . . . . . . . . . . . . . . . . . . . . . . . 214 ISO Thread Series Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Nonmandatory AppendicesA Superseded Thread Series Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
38、. . . . . 25B ISO Symbols for Screw Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26C Greek Alphabet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27ivFOREWORDThe first revision of ASA B1.
39、7-1949, the first American Standard on Nomenclature, Definitions,and Letter Symbols for Screw Threads, was approved in January 1965. These earlier definitionsand symbols were subsequently published as appendix material in ASA B1.1, B2.1, and B2.2. Assuch they underwent some revision over the years.
40、A draft based on such revisions, dated July1961, was prepared by Subcommittee 8 and widely circulated by the sponsors for comment. Ex-tensive comments were received from members of Sectional Committee B1, B2, B4, and others,which were reviewed and acted upon at a meeting of Subcommittee 8, held Nove
41、mber 28, 1961.A second revised draft, dated July 1962, was prepared and submitted to the American-British-Canadian Conference on Engineering Standards, held in Harriman, New York on September2226, 1962. Suggested revisions agreed upon by the conference were embodied in the draft,which was then submi
42、tted to letter ballot by Sectional Committees B1 and B2 on July 9, 1963.Further refinements were made in the proposal because of comments received from the sec-tional committee ballots, and a new draft was issued in May 1964. The draft was submitted tothe American Standards Association for approval
43、and designation as an American Standard. Thiswas granted on January 19, 1965, and reaffirmed in 1972 by the American National Standards In-stitute as American National Standard ANSI B1.7.Following the 1972 reaffirmation, comments from members of the American National Stan-dards Committee B1, and oth
44、ers, indicated that a complete revision be undertaken. A new draftwas prepared and submitted in March 1975 to Subcommittee 7 for review and approval. Afternumerous comments and subsequent changes, the proposed standard was submitted to and ap-proved by American National Standards Committee B1. The d
45、ocument was then transmitted tothe Secretariat and ANSI in October 1976. It was approved as an American National Standard,ANSI B1.7-1977, on September 16, 1977.Within the period from 1977 to 1984 there was considerable B1 standards activity in the de-velopment of metric screw thread standards for U.
46、S. usage. ISO standards were blended withANSI standards, requiring many revisions in ANSI symbology and definitions of terms. ISO sym-bols were adopted, except those where a change from American practice would confuse the gen-eral understanding of the elements symbolized. Also, many ISO definitions
47、were incorporatedinto American definitions in order to facilitate the correct interpretation of both ISO and ANSIterminology. These revisions were approved and designated as American National StandardANSI/ASME B1.7M-1984, on November 2, 1984.Screw thread standards are constantly being revised as req
48、uired by the ASME B1 Committee.Additionally, the title of this document was changed to “Screw Threads: Nomenclature, Defini-tions, and Letter Symbols.” This revision was approved and designated by the American Na-tional Standards Institute on September 11, 2006.vASME B1 COMMITTEEScrew Threads(The fo
49、llowing is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSA. L. Barrows, ChairD. S. George, Vice ChairA. L. Guzman, SecretarySTANDARDS COMMITTEE PERSONNELA. L. Barrows,Kennametal, Inc. B. Larzelere, Corresponding Member, Deltronic Corp.F. G. Calderone, Corresponding Member, Quality L. L. Lord, Corresponding Member, ConsultantSystems Implementers M. H. McWilliams,PMC LonestarL. N. Dixon, Jr.,General Electric D. R. Maisch, Alternate, PMC LonestarR. Dodge,Pennoyer-Dodge Co. D. Miskinis,Kennametal, Inc.D. Everett,National Institute of Standar
