ASME B1.7M-01 Nomenclature Definitions and Letter Symbols for Screw Threads
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FA96A66BE8DA4547AD8F2D48B3C81C83 |
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0.54 |
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页数： |
9 |
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日期： |
2013-6-4 |
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crew NOMENCLATURE, DEFINITIONS, AND,HRRDS LETTER SYMBOLS FOR SCREW THREADS,Abstract of,ANSI/ASME,BUM,、1984 (R 2001) ,代,IFI notes：,兔落专业丰富,1 . ANSIIASME B 1.7M is a standard developed through the procedures,of The American Society of Mechanical Engineers. B1.7M is under,the jurisdiction ofASME Standards Committee B1,2 B1.7M establishes uniform practices for standard screw threads,with regard to screw thread nomenclature and letter symbols. B1.7M,consists of a glossary of terms, an illustrated table showing the,application of symbols, and a table of thread series designations.,B 1.7M applies to both inch and metric series screw threads. In,1984, B1.7M was extensively revised to incorporate ISO (International,Organization for Standardization) nomenclature, terms and,symbols where the definitions were consistent with USA practice.,This abstract is limited to a presentation of the BUM definitions of,terms commonly associated with "straight" Unified inch series,screw threads. For the omitted information, refer to the complete,standard, copies of which are available from ASME.,3, ANSIIASME B1,7M-1984 (R 2001) is abstracted with the permission,of its publisher, The American Society of Mechanical Engineers,Three Park Avenue, New York, NY 10016-5990, U.S.A.,DEFINITION OF TERMS,Definitions are listed alphabetically and,apply generally to all forms of screw threads,thread gages, and thread measurement. They,relate to the following:,(a) types of screw threads;,(b) size and fit of threaded parts in general;,(c) geometric elements, attributes, and dimensions,of screw threads.,actual fit - the measured difference, before,assembly, between the sizes of two mating parts,which are to be assembled.,actual size — the measured size of a characteristic,or attribute.,allowance - the prescribed difference between,the design (maximum material) size and the,basic size.,attribute — an essential quality or characteristic.,Inspection by attributes implies acceptance,by limit gages.,axis of thread——the axis of the thread pitch cylinder.,basic profile of thread — the cyclical outline, in,an axial plane, of the permanently established,boundary between the provinces of the external,and internal threads. All deviations are with respect,to this boundary.,basic size — that size from which the limits of,size are derived by the application of allowances,and tolerances.,A —24 . 2003 Industrial Fasteners Institute,NOMENCLATURE, DEFINITIONS, AND,LETTER SYMBOLS FOR SCREW THREADS,Abstract of,ANSI/ASME,B1.7M,1984 (R 2001),SCREW,THREADS,bilateral tolerance — a tolerance in which variation,is permitted to be both larger and smaller,than the specified dimension.,chamfer ——the conical surface at the starting,end of a thread.,characteristics — qualities, peculiarities, or features,which are conspicuous or prominent details,of the thread.,class of thread — an alphanumerical designation,to indicate the standard grade of tolerance,and allowance specified for a thread.,clearance fit ——a fit between mating assembled,parts that provides a clearance at their maximum,material condition.,clearance flank — the flank that does not take,the externally applied axial load in an assembly.,complete thread—the thread whose profile lies,within the size limits. See effective thread, length,of complete thread.,countersink ——a bevel or flare at the end of a,hole.,crest — the surface of a thread that joins the,flanks of the thread and is farthest from the cylinder,from which the thread projects.,crest diameter— the diameter of an imaginary,cylinder bounding the crest of a screw thread.,This is the major diameter of an external thread,or the minor diameter of an internal thread.,crest truncation——the crest truncation of a thread,is the radial distance between the sharp crest,(crest apex) and the cylinder that would bound,the crest.,cumulative form variation — the combined effect,on functional size of individual thread variations,in lead (pitch), helix, flank angle, taper, and,roundness. It is the maximum difference between,GO functional diameter and pitch diameter.,cumulative pitch — the distance measured parallel,to the axis of the thread between corresponding,points on any two threads regardless,of whether they are in the same axial plane.,cylindricity——the condition of a surface of revolution,in which all points of the surface are equidistant,from a common axis.,NOTE: The cylindricity tolerance is a composite control of,form which includes roundness, straightness, and taper of,a cylindrical feature.,depth of thread engagement ——the radial distance,crest to crest, by which the thread forms,overlap between two coaxially assembled mating,threads.……
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