第9讲螺纹连接件的画法

1第九讲螺纹连接(Threads)1.螺纹要素及分类KeyElementsandtypes2.内外螺纹画法Representationsofinternalandexternalthreads3.螺纹联接Threadedconnection4.螺纹紧固件Threadedfasteners2螺孔Threadedhole39.1螺纹的形成、结构和要素Generation,structureandkeyelementsofthread⒈螺纹的形成GenerationA●螺旋线Helix一个与轴线共面的平面图形（三角形、梯形等），绕圆柱面作螺旋运动，则得到一圆柱螺旋体——螺纹。Acylinderthreadisalongnarrowprojectionofuniformcrossthesectionintheformofhelixontthesurfaceofacylinder制在圆柱体外表面上的螺纹叫外螺纹。Externalthreadisathreadontheoutsideofacylindricalsurface,asonashaft.制在圆柱体内表面上的螺纹叫内螺纹。Internalthreadisathreadontheinsideofacylindricalsurface,asinahole.4车外螺纹Latheexternalthread车内螺纹Latheinternalthread工件AShaft卡盘Fixture车刀Cutter工件旋转Thepartrotates车刀沿轴向移动Thecuttermovealongtheaxis2.螺纹加工Machiningscrewthread5⒊螺纹的要素KeyElementsofthreads⑴螺纹的牙型Formofthread三角形Metric在通过螺纹轴线的剖面上，螺纹的轮廓形状。Thecrosssectionofthreadcutbyaplanecontainingtheaxis.梯形ACME锯齿形Buttress常用的有：Mostoftenused:牙型Form6⑵螺纹的大径和小径Majordiameterandminordiameter大径：与外螺纹牙顶或内螺纹牙底相切的假想圆柱面的直径。D、dMajordiameter:Thelargestdiameterofascrewthread小径：与外螺纹牙底或内螺纹牙顶相切的假想圆柱面的直径。D1、d1Minordiameter:Thesmallestdiameterofascrewthread牙顶Crest牙顶Crest牙底Root牙底Root小径大径7外螺纹Externalthread内螺纹Internalthread牙顶Crest牙底Root牙底Root牙顶Crest大径MajorDia.D、d小径Minordia.D1、d1中径Pitchdia.D2、d2螺纹的中径Pitchdiameter：一个假想圆柱的直径。该圆柱的母线通过牙型上沟槽和凸起宽度相等的地方。Thediameterofanimaginarycylinderwherethethreadwidthisequaltospacebetweenthethreads.8⑶螺纹的线数Numberofthreads•沿一条螺旋线形成的螺纹叫做单线螺纹；Singlethread:withonlyonestart.•沿两条或两条以上在轴向等距分布的螺旋线所形成的螺纹叫做多线螺纹。Multiplethread:withtwoormorestarts单线螺纹Singlethread双线螺纹Multiplethread瓶口三线螺纹Triple-startthread9⑷螺距和导程PitchandLead螺纹上相邻两牙在中径线上对应两点之间的轴向距离P称为螺距。Pitch:Thedistancefromapointononethreadtothecorrespondingpointontheadjacentthread,measuredparalleltotheaxisofthethread.同一条螺纹上相邻两牙在中径线上对应两点之间的轴向距离L称为导程。Lead:Thedistanceathreadadvancesaxiallyinoneturn.单线螺纹(Singlethread)：P=L多线螺纹(Multiplethread)：P=L/n螺距P=导程L螺距P导程L10⑸螺纹的旋向Howthethreadspiral右旋(常用):顺时针旋转外螺纹时旋入的螺纹为右旋。除非特别注明，螺纹均为右旋Right-hand(Default)：Athreadisalwaysconsideredtoberight-handunlessotherwisespecified.左旋:加标记：“LH”Left-hand：alwayslabeled‘LH’ondrawing注意：只有上述五要素完全相同的内、外螺纹才能旋合在一起。Theexternalthreadandinternalthreadcanbematedonlywhentheirfiveelementsareallthesame.右旋Right-hand左旋Left-hand右边升高Slantupwardtotheright左边升高Slantupwardtotheleft11螺尾Threadrunout倒角Chamfer牙顶Crest牙底Root牙型Threadform中径Pitchdia.牙型Threadform小径Minordia.螺距Pitch螺距Pitch外螺纹Externalthread内螺纹Internalthread大径Majordia.内外螺纹旋合三要素：牙型、大径、螺距Threekeyelementsformating:threadform,majordia.andpitch12退刀槽Threadrelief螺尾Threadrunout螺纹收尾和退刀槽Threadrunoutandrelief退刀纹Incompletethreadduetotoolexits开始退刀Cuttingtoolbeginstoexit退出车刀Exitcompletely外退刀槽Externalrelief内退刀槽Internalrelief退刀纹Incompletethread139.2螺纹的种类Classificationofthreadscommonlyused螺纹Thread连接螺纹Connecting传动螺纹Transmitting普通螺纹Metricthread管螺纹Pipethread粗牙螺纹Coarse细牙螺纹Fine梯形螺纹Trapezoidalthread锯齿形螺纹Buttressthread密封管螺纹Screw-sealed非密封管螺纹Non-screw-sealed14联接螺纹Conne-cting传动螺纹Transm-issionMGTrB粗牙Coarse细牙Fine螺纹Metric管螺纹Pipethread梯形螺纹Trapezoidal锯齿形螺纹Buttress普通是最常用的联接螺纹Mostoftenusedconnectingthread用于细小的精密或薄壁零件Usedforfineorthinpart用于水管、油管、气管等薄壁管子上，用于管路的联接。Usedforconnectionofpipesortubesofwater,oilorgas用于各种机床的丝杠，作传动用。Powertransmission,likeinleadscrew.只能传递单方向的动力。Transmitpowerinonedirectiononly,likeinacarjack螺纹种类Types特征代号Labels外形图Profiles用途Use常用的几种螺纹的特征代号及用途Thelabelsandcommonusesofsomethreads159.3螺纹的规定画法Conventionalrepresentationofthreads★牙顶用粗实线表示(外螺纹的大径线，内螺纹的小径线)。Thecrestline(i.e.majordia.forexternalthreadandminordia.forinternalthread)definedbythicksolidline.★牙底用细实线表示(外螺纹的小径线，内螺纹的大径线)。Therootline(i.e.minordia.forexternalthreadandmajordia.forinternalthread)definedbythinsolidline.★在投影为圆的视图上，表示牙底的细实线圆只画约3/4圈。Onanendview,therootshouldberepresentedbyacircleofapproximately3/4ofthecircumferencedrawnbythinsolidline.★螺纹终止线用粗实线表示。Thethreadendlines(Thelimitsofusefulthread)shouldbeshownbyathicksolidline.★不管是内螺纹还是外螺纹，其剖视图或断面图上的剖面线都必须画到粗实线。Forthreadedpartsshowninasectionalview,Thesectionlinesshouldbeextendedtothethicksolidlines.16螺纹终止线画粗实线Threadendlinebythicksolidline⒈外螺纹画法Representationofexternalthreads小径线画细实线且画到倒角内Minordia.bythinsolidlinesandextendedcrossthechamferline小径≈0.85d倒角圆不画Chamfercirclenotshownonsuchview小径圆约画3/4圈Minordia.byathinsolidlinecircleofapproximately3/4外螺纹剖视画法：Sectionofexternalthread:小径大径A－A螺纹终止线画一小段Threadendlineappearsshort剖面线画到粗实线SectionlinesextendedtothicksolidlinesAA大径线画粗实线Majordia.bythicksolidlines17螺纹终止线Threadendlinebythicksolidline⒉内螺纹画法RepresentationofInternalthreads大径线画细实线Majordia.bythinsolidlines小径线画粗实线，≈0.85dMinordia.bythicksolidlinesandextendedcrossthechamferline倒角圆不画Chamfercirclenotshownonsuchview大径圆约画3/4圈Majordia.byathinsolidlinecircleofapproximately3/4剖面线画到粗实线SectionlinesextendedtothicksolidlinesAAA－A18120°0.5D不穿通螺纹孔的画法Blindtappedhole:钻孔Drill攻丝Tap19C2⒊螺纹局部结构的画法⑴倒角Chamfer⑵退刀槽Relief⑶螺尾Runout2×45°2×45°b与轴线成30°细实线Thinsolidlines30°totheaxis•螺尾只在有要求时才画，不需标注。Runoutnotshownunlessit’srequired.P505表20A－A4.螺纹联接的画法RepresentationofthreadedconnectionAA旋入深度Lengthofscrewed•大径线和大径线对齐；小径线和小径线对齐。Twomajordiametersarecollinear,sodoesthetwominordiameters.•旋合部分按外螺纹画；其余部分按各自的规定画。Forthr