1、AN AMERICAN NATIO NAL STANDARDScrew Threads:Nomenclature,Definitions,and Letter Symbols ASME B1.7-2006(Revision of ANSI/ASME B1.7M-1984)REAFFIRMED 2021Intentionally left blank ASME B1.7-2006(Revision of ANSI/ASME B1.7M-1984)Screw Threads:Nomenclature,Definitions,andLetter SymbolsThree Park Avenue Ne
2、w York,NY 10016AN 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 tra
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9、AN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword.vCommittee Roster .vi1General .12Definition of Terms .1Figures1Allowance.22Axis of Thread .23Best Wire Size.24Blunt Start Thread .35Bottom of Chamfer.46Clearance Flank .47Countersink .48Crest.49Root and Crest Trun
10、cation.510Fundamental Deviation .611Metric Tolerance System for Screw Threads .712Element.713Flank.714Flank Angle .715Flat Form .716Following Flank .817Gauge Plane .818Height of Fundamental Triangle .819Height of Thread .920Height of Thread Engagement.921Helix.922Helix Variation(Drunken Thread).923I
11、ncomplete Thread .1024Interference Fit .1125Internal Thread.1126Lead .1127Leading Flank.1128Gaging Length .1129Length of Assembly .1130Length of Thread Engagement.1231Load Flank .1232Major Clearance .1233Major Diameter,External Thread.1234Major Diameter,Internal Thread .1235Major Diameter,Internal T
12、hread(Rounded Form).1236Major Diameter,Taper Thread.1237Minor Clearance.1338Minor Diameter,External Thread(Flat Form).1439Minor Diameter,External Thread(Rounded Form).1440Minor Diameter,Internal Thread.1441Minor Diameter,Taper Thread .1442Multiple Start Thread.14iii43Pitch .1444Pitch Cone .1445Pitch
13、 Cylinder .1446Pitch Diameter,External Thread .1547Pitch Diameter,Internal Thread.1548Plane of Vanish Point.1549Profile,Basic Thread.1650Root Radius .1651Screw Thread .1652Sharp Crest and Root.1653Shear Area .1754Straight Thread.1855Thread Angle .2356Thread Ridge Thickness.2357Truncation .2358Vanish
14、 Cone.24Tables1General Symbols.192ISO General Symbols .203Thread Series Designations .214ISO Thread Series Designations .22Nonmandatory AppendicesASuperseded Thread Series Designations.25BISO Symbols for Screw Threads.26CGreek Alphabet .27ivFOREWORDThe first revision of ASA B1.7-1949,the first Ameri
15、can 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.A draft based on such revision
16、s,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 November 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 co
