第9讲螺纹连接件的画法

第九讲螺纹连接(Threads)螺纹要素及分类KeyElementsandtypes内外螺纹画法Representationsofinternalandexternalthreads螺纹联接Threadedconnection螺纹紧固件Threadedfasteners1螺孔Threadedhole29.1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.3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Machiningscrewthread4⒊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Form5⑵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、d1

Minordiameter:

Thesmallestdiameterofascrewthread牙顶Crest牙顶Crest牙底Root牙底Root小径大径6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.7⑶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-startthread8⑷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L9⑸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Slantupwardtotheleft10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:thread

form,majordia.andpitch11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Incompletethread129.2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-sealed13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Thelabelsandcommonusesofsomethreads149.3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,The

sectionlinesshouldbeextendedtothethicksolidlines.15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.bythicksolidlines

16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，≈0.85d

Minordia.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－A17120°0.5D不穿通螺纹孔的画法Blindtappedhole:钻孔Drill攻丝Tap18C2φ⒊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19A－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。Forthreadedconnectionpart,externalthreadcoversinternalthread.按不剖画Asnon-sectioned内、外螺纹剖面线方向相反Reversedsectionlinesforinternalandexternalthreads为什么？20画图步骤Steps：画外螺纹（小径画0.85d）Externalthread(Majordia.as0.85d)确定内螺纹的端面位置Determinethelocationofinternalthreadends画内螺纹及其余部分投影Finishtheremainingpartofinternalthread.219.4螺纹的标注Threaddesignation⒈标注的基本模式Generalsymbols螺纹代号Designationofthreads公称直径Nominaldia.×螺距或导程(P螺距)PitchorLead(P&pitchvalue)LH(如为左旋)LH(ifleft-hand)一个或两个公差带代号Oneortwotolerancezonesymbols－旋合长度代号Symbolforlengthofengagement粗牙螺纹不标注螺距；P502旋合长度为中等时，“N”可省略。右旋螺纹省略标注;长Long：L中等Middle：N短Short：S中径和顶径公差带代号－22⒉标注示例ExampleM20×2LH-5g6g-s普通螺纹Metricthread大径Majordia.d＝20螺距2(细牙)Pitchis2(finethread)短旋合长度Shortengagementlength顶径公差带代号Majordia.tolerancezone左旋Left-hand中径公差带代号Pitchdia.tolerancezone例1：例2：Tr40×7(14/2)－7H－L梯形螺纹Trapezoidalthread大径Majordia.D＝40螺距

7导程14,双线螺纹Pitchis7,leadis14,doublethread.中径、顶径公差带代号Majordia.andpitchdia.tolerancezone长旋合长度Longengagementlength右旋Righthand两公差相同则只标一个。小写字母表示外螺纹，大写字母表示内螺纹。Ifthetwotolerancezonesymbolsarethesame,onlyoneindicated。Capitalforinternalandsmallforexternalthreads.P50223M20×2⒊标注方法ThreadnotesM20-7HG1外螺纹External尺寸界线应从大径引出！Theextensionlinesshouldbefromthemajordia.管螺纹注：

G后面的数字不是管螺纹的大径，而是它的公称直径。Thevalueafterletter“G”isnotthemajordia.butitsnominaldia.内螺纹Internal1in=25.4mmP504P502249.5螺纹紧固件的标记和画法Threadedfasteners常用的螺纹紧固件有：螺栓、螺钉、螺柱、螺母和垫圈等。由于这类零件都是标准件，通常只需在装配图中用简化画法画出，同时给出其规定标记。标记方法按“GB”有关规定。

Threadedfasteners,whichincludebolts,screw,stud,nutandwasher

etc.,arestandardized.Onassemblydrawingstheyarespecifiedbymeansofdesignationsandshowninconventionalrepresentation.Designationaccordingto“GB”25⒈六角螺母

NutsP513规定标记Specifieddesignation：螺母GB/T6170M122d0.8d简化画法Simplifieddrawing：国标号GBsymbolfornuts螺纹规格Threadsize例：比例画法见P414图15-20SeeP414Fig.15-20forproportionaldrawingas26⒉六角头螺栓BoltsP506规定标记：Specifieddesignation螺栓GB/T5782M12×80（由设计决定）Determinedbydesign0.7dL2dd0.1d×45°简化画法：Simplifieddrawing螺栓长度LLengthofstudL例：比例画法见P414图15-20SeeP414Fig.15-20forproportionaldrawingas27⒊垫圈WashersP514规定标记：Specifieddesignation垫圈GB/T9712简化画法Simplifieddrawing

：规格,指用于M12的螺栓或螺柱Size12meansthatitisusedforM12boltsorstuds0.15d1.1d2.2d例：

P514为平垫圈，P515为弹簧垫圈P514showsplainwasherswhileP515aboutspringwashers28⒋螺钉ScrewsP511规定标记：Specifieddesignation螺钉GB/T65M8×450.2d0.3d1.5dd0.6dL2d0.1d×45°开槽圆柱头螺钉Slottedcheesedheadscrew简化画法：Simplifieddrawing例：P508内六角圆柱头螺钉Hex.SocketcheeseheadscrewP510开槽沉头螺钉Slottedcountersunkheadscrew螺钉长度LLengthofscrewL29⒈螺栓联接Boltjoints9.6螺纹紧固件装配图的画法Representationoffastenersinassemblydrawing用于将两个都有通孔的零件联接Usedtoholdtwopartstogethereachofwhichhasathroughandclearancehole.30δ1L螺栓联接装配图画法DrawingofboltjointsLd=δ1+δ2+0.15d(垫圈厚heightofwasher)+0.8d(螺母厚heightofnut)+0.3d螺栓、垫圈、螺母沿轴线剖到按不剖画Bolt,washerandnutasnon-sectionedalongtheaxis螺栓的有效长度按下式计算Designlengthoftheboltiscalculatedas:将Ld与标准规定的公称长度系列L比较，选择最接近于计算值的公称长度。（P506)ComparethelengthLdwiththenominallengthLseriesspecifiedinthestandardandchoosetheoneclosesttothecalculatedvalue.两块板的剖面线方向相反Reserveddirectionsofsectionlinesfortwoparts0.3dδ2被联接件的孔径=1.1dHolesintwopartsdrawnasdiametersof1.1d

螺栓大径为dMajordia.Oftheboltisd参见P416图15-23RefertoP416Fig.15-2331画图步骤Steps:先画俯视图较方便Topviewfirstrecommended322.螺钉联接Screwjoints

螺钉连接用于受力不大且不要求调整的机构。Screwjointsareusedonmachinesrequiringfewadjustmentsandlowerstrength.光孔Clearancehole螺纹孔Tappedhole33δbmL0.5d旋合长度bm与被零件材料有关:Lengthofscrewedbmisdeterminedbymaterialofjointedpart:钢Steel：bm=d铸铁Castiron:bm=1.25d铜Copper:bm=1.5d铝Aluminum:bm=2d螺钉计算长度：Lengthcalculatedby:Ld=bm+δ查表定L-P511FindLinlistofP511参见P418图15-28RefertoP418Fig.15-28螺钉联接画法Drawingofboltjoints45°34常见的错误画法Incorrectdrawings：允许将螺纹画到底Simplifiedrepresentationpermitted螺钉末端应不拧到底Thescrewshouldnottouchtheendofthetappedhole.螺纹终止线应高于两零件分界Threadendlineshouldbehigherthanthedemarcationline√××35锥顶角度？Whatistheangle?倾斜角度？Howinclined?剖面线画到何处？Wherethesectionlinesextendedto?画在何处？Thestructureofthecone?36

3.双头螺柱联接Astudjoints光孔Clearancehole螺纹孔Tappedhole螺柱联接用于零件材料较厚不能制通孔的机构。Studjointsareusedonmachineswhicharedifficulttodrillthroughholesin.螺母端Nutend旋入端Metalend37双头螺柱联接画法RepresentationofstudjointsbmLLd=+0.15d+0.8d+0.3d旋合长度bm（即螺柱旋入端长度），同螺钉一样由被联接件的材料决定。

Asinscrewjoint,lengthofscrewedbmis（i.e.thelengthofmetalendofthestud）determinedbymaterialofjointedpart查表P507螺柱画法参见P415图15-20，螺母端螺纹长度可近似为2d。SeeP415Fig.15-20fordrawingofstud，thelengthofnutendcanbedrawnas2d.螺柱联接画法参见P417图15-25和15-26RefertoP417Fig.15-25and15-26对齐Aligned38小结Conclusion1.在螺纹的规定画法中，要抓住三条线。Thekeyisthreelinesintheconvention