第9講螺紋連接件的畫法

第九講螺紋連接(Threads)螺紋要素及分類KeyElementsandtypes內(nèi)外螺紋畫法Representationsofinternalandexternalthreads螺紋聯(lián)接Threadedconnection螺紋緊固件Threadedfasteners1螺孔Threadedhole29.1螺紋的形成、結(jié)構(gòu)和要素Generation,structureandkeyelementsofthread⒈螺紋的形成GenerationA●螺旋線Helix一個與軸線共面的平面圖形（三角形、梯形等），繞圓柱面作螺旋運(yùn)動，則得到一圓柱螺旋體

——螺紋。Acylinderthreadisalongnarrowprojectionofuniformcrossthesectionintheformofhelixontthesurfaceofacylinder制在圓柱體外表面上的螺紋叫外螺紋。Externalthreadisathreadontheoutsideofacylindricalsurface,asonashaft.制在圓柱體內(nèi)表面上的螺紋叫內(nèi)螺紋。Internalthreadisathreadontheinsideofacylindricalsurface,asinahole.3車外螺紋Latheexternalthread車內(nèi)螺紋Latheinternalthread工件AShaft卡盤Fixture車刀Cutter工件旋轉(zhuǎn)Thepartrotates車刀沿軸向移動Thecuttermovealongtheaxis2.螺紋加工Machiningscrewthread4⒊螺紋的要素KeyElementsofthreads⑴螺紋的牙型Formofthread三角形Metric在通過螺紋軸線的剖面上，螺紋的輪廓形狀。Thecrosssectionofthreadcutbyaplanecontainingtheaxis.梯形ACME鋸齒形Buttress常用的有：Mostoftenused:牙型Form5⑵螺紋的大徑和小徑Majordiameterandminordiameter大徑：與外螺紋牙頂或內(nèi)螺紋牙底相切的假想圓柱面的直徑。D、dMajordiameter:

Thelargestdiameterofascrewthread小徑：與外螺紋牙底或內(nèi)螺紋牙頂相切的假想圓柱面的直徑。D1、d1

Minordiameter:

Thesmallestdiameterofascrewthread牙頂Crest牙頂Crest牙底Root牙底Root小徑大徑6外螺紋Externalthread內(nèi)螺紋Internalthread牙頂Crest牙底Root牙底Root牙頂Crest大徑MajorDia.D、d小徑Minordia.D1、d1中徑Pitchdia.D2、d2螺紋的中徑Pitchdiameter：一個假想圓柱的直徑。該圓柱的母線通過牙型上溝槽和凸起寬度相等的地方。Thediameterofanimaginarycylinderwherethethreadwidthisequaltospacebetweenthethreads.7⑶螺紋的線數(shù)Numberofthreads沿一條螺旋線形成的螺紋叫做單線螺紋；Singlethread:withonlyonestart.沿兩條或兩條以上在軸向等距分布的螺旋線所形成的螺紋叫做多線螺紋。Multiplethread:withtwoormorestarts單線螺紋Singlethread雙線螺紋Multiplethread瓶口三線螺紋Triple-startthread8⑷螺距和導(dǎo)程PitchandLead螺紋上相鄰兩牙在中徑線上對應(yīng)兩點(diǎn)之間的軸向距離P稱為螺距。Pitch:Thedistancefromapointononethreadtothecorrespondingpointontheadjacentthread,measuredparalleltotheaxisofthethread.

同一條螺紋上相鄰兩牙在中徑線上對應(yīng)兩點(diǎn)之間的軸向距離L稱為導(dǎo)程。Lead:Thedistanceathreadadvancesaxiallyinoneturn.單線螺紋(Singlethread)：P=L多線螺紋(Multiplethread)：P=L/n螺距P=導(dǎo)程L螺距P導(dǎo)程L9⑸螺紋的旋向Howthethreadspiral右旋(常用):順時針旋轉(zhuǎn)外螺紋時旋入的螺紋為右旋。除非特別注明，螺紋均為右旋Right-hand(Default)：Athreadisalwaysconsideredtoberight-handunlessotherwisespecified.左旋:加標(biāo)記：“LH”

Left-hand：alwayslabeled‘LH’ondrawing注意：只有上述五要素完全相同的內(nèi)、外螺紋才能旋合在一起。Theexternalthreadandinternalthreadcanbematedonlywhentheirfiveelementsareallthesame.右旋Right-hand左旋Left-hand右邊升高Slantupwardtotheright左邊升高Slantupwardtotheleft10螺尾Threadrunout倒角Chamfer

牙頂Crest牙底Root牙型Threadform中徑Pitchdia.牙型Threadform

小徑Minordia.螺距Pitch

螺距Pitch

外螺紋Externalthread內(nèi)螺紋Internalthread大徑Majordia.內(nèi)外螺紋旋合三要素：牙型、大徑、螺距Threekeyelementsformating:thread

form,majordia.andpitch11退刀槽Threadrelief螺尾Threadrunout螺紋收尾和退刀槽Threadrunoutandrelief退刀紋Incompletethreadduetotoolexits開始退刀Cuttingtoolbeginstoexit退出車刀Exitcompletely外退刀槽Externalrelief內(nèi)退刀槽Internalrelief退刀紋Incompletethread129.2螺紋的種類Classificationofthreadscommonlyused螺紋Thread連接螺紋Connecting傳動螺紋Transmitting普通螺紋Metricthread管螺紋Pipethread

粗牙螺紋Coarse細(xì)牙螺紋Fine

梯形螺紋Trapezoidalthread鋸齒形螺紋Buttressthread密封管螺紋Screw-sealed非密封管螺紋Non-screw-sealed13聯(lián)接螺紋Conne-cting傳動螺紋Transm-issionMGTrB粗牙Coarse細(xì)牙Fine螺紋Metric管螺紋Pipethread梯形螺紋Trapezoidal鋸齒形螺紋Buttress普通是最常用的聯(lián)接螺紋Mostoftenusedconnectingthread用于細(xì)小的精密或薄壁零件Usedforfineorthinpart用于水管、油管、氣管等薄壁管子上，用于管路的聯(lián)接。Usedforconnectionofpipesortubesofwater,oilorgas用于各種機(jī)床的絲杠，作傳動用。Powertransmission,likeinleadscrew.只能傳遞單方向的動力。Transmitpowerinonedirectiononly,likeinacarjack螺紋種類Types特征代號Labels外形圖Profiles用途Use常用的幾種螺紋的特征代號及用途Thelabelsandcommonusesofsomethreads149.3螺紋的規(guī)定畫法Conventionalrepresentationofthreads★牙頂用粗實(shí)線表示

(外螺紋的大徑線，內(nèi)螺紋的小徑線)。Thecrestline(i.e.majordia.forexternalthreadandminordia.forinternalthread)definedbythicksolidline.★牙底用細(xì)實(shí)線表示(外螺紋的小徑線，內(nèi)螺紋的大徑線)。Therootline(i.e.minordia.forexternalthreadandmajordia.forinternalthread)definedbythinsolidline.★在投影為圓的視圖上，表示牙底的細(xì)實(shí)線圓只畫約3/4圈。Onanendview,therootshouldberepresentedbyacircleofapproximately3/4ofthecircumferencedrawnbythinsolidline.★螺紋終止線用粗實(shí)線表示。Thethreadendlines(Thelimitsofusefulthread)shouldbeshownbyathicksolidline.★不管是內(nèi)螺紋還是外螺紋，其剖視圖或斷面圖上的剖面線都必須畫到粗實(shí)線。Forthreadedpartsshowninasectionalview,The

sectionlinesshouldbeextendedtothethicksolidlines.15螺紋終止線畫粗實(shí)線Threadendlinebythicksolidline⒈外螺紋畫法Representationofexternalthreads小徑線畫細(xì)實(shí)線且畫到倒角內(nèi)Minordia.bythinsolidlinesandextendedcrossthechamferline小徑≈0.85d倒角圓不畫Chamfercirclenotshownonsuchview小徑圓約畫3/4圈Minordia.byathinsolidlinecircleofapproximately3/4外螺紋剖視畫法：Sectionofexternalthread:小徑大徑A－A螺紋終止線畫一小段Threadendlineappearsshort

剖面線畫到粗實(shí)線SectionlinesextendedtothicksolidlinesAA

大徑線畫粗實(shí)線Majordia.bythicksolidlines

16螺紋終止線Threadendlinebythicksolidline⒉內(nèi)螺紋畫法RepresentationofInternalthreads大徑線畫細(xì)實(shí)線Majordia.bythinsolidlines

小徑線畫粗實(shí)線，≈0.85d

Minordia.bythicksolidlinesandextendedcrossthechamferline

倒角圓不畫Chamfercirclenotshownonsuchview大徑圓約畫3/4圈Majordia.byathinsolidlinecircleofapproximately3/4剖面線畫到粗實(shí)線SectionlinesextendedtothicksolidlinesAAA－A17120°0.5D不穿通螺紋孔的畫法Blindtappedhole:鉆孔Drill攻絲Tap18C2φ⒊螺紋局部結(jié)構(gòu)的畫法⑴倒角Chamfer⑵退刀槽Relief⑶螺尾Runout2×45°2×45°b與軸線成30°細(xì)實(shí)線Thinsolidlines30°totheaxis螺尾只在有要求時才畫，不需標(biāo)注。Runoutnotshownunlessit’srequired.P505表19A－A4.螺紋聯(lián)接的畫法RepresentationofthreadedconnectionAA旋入深度Lengthofscrewed

大徑線和大徑線對齊；小徑線和小徑線對齊。Twomajordiametersarecollinear,sodoesthetwominordiameters.旋合部分按外螺紋畫；其余部分按各自的規(guī)定畫。Forthreadedconnectionpart,externalthreadcoversinternalthread.按不剖畫Asnon-sectioned內(nèi)、外螺紋剖面線方向相反Reversedsectionlinesforinternalandexternalthreads為什么？20畫圖步驟Steps：畫外螺紋（小徑畫0.85d）Externalthread(Majordia.as0.85d)確定內(nèi)螺紋的端面位置Determinethelocationofinternalthreadends畫內(nèi)螺紋及其余部分投影Finishtheremainingpartofinternalthread.219.4螺紋的標(biāo)注Threaddesignation⒈標(biāo)注的基本模式Generalsymbols螺紋代號Designationofthreads公稱直徑Nominaldia.×螺距或?qū)С?P螺距)PitchorLead(P&pitchvalue)LH(如為左旋)LH(ifleft-hand)一個或兩個公差帶代號Oneortwotolerancezonesymbols－旋合長度代號Symbolforlengthofengagement粗牙螺紋不標(biāo)注螺距；P502旋合長度為中等時，“N”可省略。右旋螺紋省略標(biāo)注;長Long：L中等Middle：N短Short：S中徑和頂徑公差帶代號－22⒉標(biāo)注示例ExampleM20×2LH-5g6g-s普通螺紋Metricthread大徑Majordia.d＝20螺距2(細(xì)牙)Pitchis2(finethread)短旋合長度Shortengagementlength頂徑公差帶代號Majordia.tolerancezone左旋Left-hand中徑公差帶代號Pitchdia.tolerancezone例1：例2：Tr40×7(14/2)－7H－L梯形螺紋Trapezoidalthread大徑Majordia.D＝40螺距

7導(dǎo)程14,雙線螺紋Pitchis7,leadis14,doublethread.中徑、頂徑公差帶代號Majordia.andpitchdia.tolerancezone長旋合長度Longengagementlength右旋Righthand兩公差相同則只標(biāo)一個。小寫字母表示外螺紋，大寫字母表示內(nèi)螺紋。Ifthetwotolerancezonesymbolsarethesame,onlyoneindicated。Capitalforinternalandsmallforexternalthreads.P50223M20×2⒊標(biāo)注方法ThreadnotesM20-7HG1外螺紋External尺寸界線應(yīng)從大徑引出！Theextensionlinesshouldbefromthemajordia.管螺紋注：

G后面的數(shù)字不是管螺紋的大徑，而是它的公稱直徑。Thevalueafterletter“G”isnotthemajordia.butitsnominaldia.內(nèi)螺紋Internal1in=25.4mmP504P502249.5螺紋緊固件的標(biāo)記和畫法Threadedfasteners常用的螺紋緊固件有：螺栓、螺釘、螺柱、螺母和墊圈等。由于這類零件都是標(biāo)準(zhǔn)件，通常只需在裝配圖中用簡化畫法畫出，同時給出其規(guī)定標(biāo)記。標(biāo)記方法按“GB”有關(guān)規(guī)定。

Threadedfasteners,whichincludebolts,screw,stud,nutandwasher

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

NutsP513規(guī)定標(biāo)記Specifieddesignation：螺母GB/T6170M122d0.8d簡化畫法Simplifieddrawing：國標(biāo)號GBsymbolfornuts螺紋規(guī)格Threadsize例：比例畫法見P414圖15-20SeeP414Fig.15-20forproportionaldrawingas26⒉六角頭螺栓BoltsP506規(guī)定標(biāo)記：Specifieddesignation螺栓GB/T5782M12×80（由設(shè)計(jì)決定）Determinedbydesign0.7dL2dd0.1d×45°簡化畫法：Simplifieddrawing螺栓長度LLengthofstudL例：比例畫法見P414圖15-20SeeP414Fig.15-20forproportionaldrawingas27⒊墊圈WashersP514規(guī)定標(biāo)記：Specifieddesignation墊圈GB/T9712簡化畫法Simplifieddrawing

：規(guī)格,指用于M12的螺栓或螺柱Size12meansthatitisusedforM12boltsorstuds0.15d1.1d2.2d例：

P514為平墊圈，P515為彈簧墊圈P514showsplainwasherswhileP515aboutspringwashers28⒋螺釘ScrewsP511規(guī)定標(biāo)記：Specifieddesignation螺釘GB/T65M8×450.2d0.3d1.5dd0.6dL2d0.1d×45°開槽圓柱頭螺釘Slottedcheesedheadscrew簡化畫法：Simplifieddrawing例：P508內(nèi)六角圓柱頭螺釘Hex.SocketcheeseheadscrewP510開槽沉頭螺釘Slottedcountersunkheadscrew螺釘長度LLengthofscrewL29⒈螺栓聯(lián)接Boltjoints9.6螺紋緊固件裝配圖的畫法Representationoffastenersinassemblydrawing用于將兩個都有通孔的零件聯(lián)接Usedtoholdtwopartstogethereachofwhichhasathroughandclearancehole.30δ1L螺栓聯(lián)接裝配圖畫法DrawingofboltjointsLd=δ1+δ2+0.15d(墊圈厚heightofwasher)+0.8d(螺母厚heightofnut)+0.3d螺栓、墊圈、螺母沿軸線剖到按不剖畫Bolt,washerandnutasnon-sectionedalongtheaxis螺栓的有效長度按下式計(jì)算Designlengthoftheboltiscalculatedas:將Ld與標(biāo)準(zhǔn)規(guī)定的公稱長度系列L比較，選擇最接近于計(jì)算值的公稱長度。（P506)ComparethelengthLdwiththenominallengthLseriesspecifiedinthestandardandchoosetheoneclosesttothecalculatedvalue.兩塊板的剖面線方向相反Reserveddirectionsofsectionlinesfortwoparts0.3dδ2被聯(lián)接件的孔徑=1.1dHolesintwopartsdrawnasdiametersof1.1d

螺栓大徑為dMajordia.Oftheboltisd參見P416圖15-23RefertoP416Fig.15-2331畫圖步驟Steps:先畫俯視圖較方便Topviewfirstrecommended322.螺釘聯(lián)接Screwjoints

螺釘連接用于受力不大且不要求調(diào)整的機(jī)構(gòu)。Screwjointsareusedonmachinesrequiringfewadjustmentsandlowerstrength.光孔Clearancehole螺紋孔Tappedhole33δbmL0.5d旋合長度bm與被零件材料有關(guān):Lengthofscrewedbmisdeterminedbymaterialofjointedpart:鋼Steel：bm=d鑄鐵Castiron:bm=1.25d銅Copper:bm=1.5d鋁Aluminum:bm=2d螺釘計(jì)算長度：Lengthcalculatedby:Ld=bm+δ查表定L-P511FindLinlistofP511參見P418圖15-28RefertoP418Fig.15-28螺釘聯(lián)接畫法Drawingofboltjoints45°34常見的錯誤畫法Incorrectdrawings：允許將螺紋畫到底Simplifiedrepresentationpermitted螺釘末端應(yīng)不擰到底Thescrewshouldnottouchtheendofthetappedhole.螺紋終止線應(yīng)高于兩零件分界Threadendlineshouldbehigherthanthedemarcationline√××35錐頂角度？Whatistheangle?傾斜角度？Howinclined?剖面線畫到何處？Wherethesectionlinesextendedto?畫在何處？Thestructureofthecone?36

3.雙頭螺柱聯(lián)接Astudjoints光孔Clearancehole螺紋孔Tappedhole螺柱聯(lián)接用于零件材料較厚不能制通孔的機(jī)構(gòu)。Studjointsareusedonmachineswhicharedifficulttodrillthroughholesin.螺母端Nutend旋入端Metalend37雙頭螺柱聯(lián)接畫法RepresentationofstudjointsbmLLd=+0.15d+0.8d+0.3d旋合長度bm（即螺柱旋入端長度），同螺釘一樣由被聯(lián)接件的材料決定。

Asinscrewjoint,lengthofscrewedbmis（i.e.thelengthofmetalendofthestud）determinedbymaterialofjointedpart查表P507螺柱畫法參見P415圖15-20，螺母端螺紋長度可近似為2d。SeeP415Fig.15-20fordrawingofstud，thelengthofnutendcanbedrawnas2d.螺柱聯(lián)接畫法參見P417圖15-25和15-26RefertoP417Fig.15-25and15-26對齊Aligned38小結(jié)Conclusion1.在螺紋的規(guī)定畫法中，要抓住三條線。Thekeyisthreelinesintheconvention