1、The American Society ofMechanical EngineersA N AME RIC AN N ATI ON ALST AN DARDMETRIC HEAVYHEX FLANGESCREWSASMB18.2.3.9M-2001Revision of ANSI/ASME B18.2.3.9M-1984(R1995)FOREWORDAmerican National Standards Committee B18 for the standardization of bolts,screws,nuts,rivets,and similar fasteners was org
2、anized in March 1922 as Sectional CommitteeB18 under the aegis of the American Engineering Standards Committee(later the AmericanStandards Association,then the United States of America Standards Institute and,as ofOctober 6,1969,the American National Standards Institute,Inc.),with the Society ofAuto
3、motive Engineers and the American Society of Mechanical Engineers as joint sponsors.Subcommittee 2 was subsequently established and charged with the responsibility for technicalcontent of standards covering wrench head bolts and nuts.At its meeting on December 4,1974,Committee B18 authorized prepara
4、tion of a seriesof standards for metric fasteners.Subcommittee 2 was assigned responsibility for developingstandards for metric hex bolts,screws,and nuts.Following issuance of ANSI B18.2.3.4M-1979,interest developed in the farm equipment,heavy truck,and off-road vehicles industries for a second seri
5、es of metric hex flange screwshaving a head widths across flats series equal to those of metric hex cap screws.Duringthe analytical research study to optimize head proportions of hex flange screws(refer tothe Foreword of ASME B18.2.3.4M-2000),this larger head series was also investigated,and appropr
6、iate values for the various head characteristics were established for screw sizesM10 through M20.This new design of metric heavy hex flange screws was submitted by the United Statesof America/Canada to ISO/TC2 at its May 1982 meetings.TC2 accepted the proposal andauthorized development of Internatio
7、nal Organization for Standardization(ISO)standards.After these ISO decisions,Subcommittee 2 drafted this Standard.This Standard was approved by letter ballot of the ASME B18 Standards Committee onApril 18,1983,and was subsequently approved by the American Society of MechanicalEngineers and submitted
8、 to the American National Standards Institute for designation asan American National Standard.This was granted on March 23,1984.The Standard wasreaffirmed in 1995.This draft revision was prepared based on revisions that were made inthe metric hex cap screw standard in December 1998.This Standard was
9、 approved by theAmerican National Standards Institute on March 9,2001.The key revisions include thefollowing:(a)The heavy hex series is expanded to include sizes M5,M6,and M8 with headdimensions adopted by ISO/DIS 8102.(b)All head heights(K)and wrenching heights(Kw)are increased to improve wrenchabi
10、lity.(c)The position of head-to-shank is changed to maximum material condition(MMC)asdescribed in para.11 and Tables 2 and 5.(d)The length tolerances are changed in Table 7 to agree with those of the draft ofASME B18.2.3.4M,Metric Hex Flange Screws.(e)Straightness is specified at MMC,and a rail gage
11、 replaces the sleeve gage as specifiedin para.18.(f)The concavity angle of the conical bearing surface is now 0.75 deg+0.50 deg toagree with that of ISO and to match B18.2.3.4M.The bearing face runout is to be measuredon the actual bearing circle instead of the minimum bearing circle as specified in
12、 para.13.(g)The transition threads shall have a rounded root contour per para.20.4.This replaces,iiiFor screws of Property Class 10.9 and higher strength materials(tensile strength 1040MPa and higher)the transition threads shall have a rounded root contour no radius ofwhich shall be less than the sp
13、ecified minimum at the root of the full form thread.(h)The position of body-to-thread previously required is deleted based on the B18Subcommittee 2 decision of December 2.1998.(i)Appendix A is added to provide a detailed comparison with ISO/DIS 8102,withunpublished changes agreed upon in ISO/TC2/WG2
14、.The current wrenching height formulain ISO 4759-1 would increase the wrenching heights even more.No support exists in NorthAmerica for increases beyond those included herein.ivASME B18 STANDARDS COMMITTEEStandardization of Bolts,Nuts,Rivets,Screws,Washers,and Similar Fasteners(The following is the
15、roster of the Committee at the time of approval of this Standard.)OFFICERSD.A.Clever,ChairR.D.Strong,Vice ChairS.W.Vass,Vice ChairR.L.Crane,SecretaryCOMMITTEE PERSONNELJ.Altman,Rotor Clip Co.J.H.Slass,Alternate,Rotor Clip CoJ.B.Belford,Lawson Products,Inc.J.A.Buda,SPS TechnologiesR.M.Byrne,Trade Ass
16、ociation Management,Inc.D.A.Clever,Deere and Co.A.P.Cockman,Ford Motor Co.T.Collier,Cam-Tech Industries,IncR.L.Crane,The American Society of Mechanical EngineersA.C.DiCola,Wrought Washer Co.B.A.Dusina,Federal Screw WorksD.S.George,Ford Motor Co.D.L.Drobnich,Alternate,Ford Motor Co.J.Greenslade,Green
17、slade and Co.B.Hasiuk,Defense Industrial Supply CenterA.Herskovitz,U.S.ArmyJ.Hubbard,Rockford Fastener,Inc.D.F.Kattler,SPS TechnologiesJ.F.Koehl,Spirol International Corp.W.H.Kopke,ITW Shakeproof Assembly Co.M.Levinson,A/ternate,ITW Shakeproof Assembly Co.J.G.Langenstein,ConsultantD.Liesche,Defense
18、Industrial Supply CenterL.L.Lord,Caterpillar,Inc.R.L.Tennis,Alternate,Caterpillar,Inc.D.B.Mantas,GE-EmpisA.D.McCrindle,Genfast Manufacturing Co.K.E.McCullough,ConsultantR.B.Meade,Textron Fastening SystemsM.D.Prasad,General Motors Corp.S.Savoji,ITW MedalistW.Schevey,BGM Fastener Co.,Inc.R.D.Strong,General Motors Corp.J.F.Sullivan,National Fasteners Distribution AssociationR.Torres,Action Threaded ProductionS.W.Vass,Industrial Fasteners InstituteC.B.Wackrow,MNP Corp.R.G.Weber,Fairfield University
