畢業(yè)設計資料 淬硬齒輪的加工

PAGEPAGE1附錄1淬硬齒輪的加工【摘要】用于動力傳動的齒輪和齒輪箱，其尺寸要求更小，齒輪傳動的噪音更低，從而導致對淬硬齒輪的需求，也給齒輪制造廠家提出了探索齒輪加工新方法的要求.概述用于動力傳動的齒輪和齒輪箱，其尺寸要求更小，齒輪傳動的噪音更低，從而導致對淬硬齒輪的需求，也給齒輪制造廠家提出了探索齒輪加工新方法的要求。齒輪在淬硬熱處理過程中，其材料組織及應力的改變，通常會使齒輪產生變形，即齒形、齒向及齒距誤差。這此誤差將引起齒廓在傳動時的不正確嚙合，從而加大了載荷，產生齒輪噪音。因此，淬硬齒輪在熱處理后，一般應添加一道精加工工序。淬硬齒輪精加工工藝可分為兩類：一類是采用非成形的切削刃，如齒輪磨削加工；另一類則是具有成形的切削刃如淬硬齒輪(HRC48～53)滾削加工。本文將集中討論用于硬滾齒加工的硬質合金刀具成形切削刃的精加工過程。當今的硬質合金材料、刀具涂層和滾齒機技術的發(fā)展，已使淬硬齒輪滾切加工技術有了顯著的提高，特別是在加工小于或等于12DP的中小模數齒輪時，可承受硬切削過程中所產生的極大的切削力。硬質合金滾刀的選取硬質合金滾刀在材料的品種規(guī)格上有很大進展。超細、細、中等或大顆粒的硬質合金現(xiàn)在都有產品。此外，硬質合金滾刀毛坯的成形工藝技術也有了顯著提高，如采用熱等靜壓(HIP)工藝，該工藝在高壓高溫下，增加了硬質合金毛坯的內在結合力，提高了硬質合金的抗彎強度。按照ISO的規(guī)定，實體硬質合金材料可按應用場合的不同分為若干類：齒輪切削刀具分為K類和P類，K類硬質合金有更高的耐磨性，P類則有更好的高溫紅硬性。在K牌號和P牌號硬質合金中，每種牌號硬質合金的顆粒結構是不同的，從中等顆粒到超細顆粒。每種牌號都有其應用場合，這是和顆粒結構相關聯(lián)的。一般來說，對于軟滾削，K類比P類的性能要好，K類硬質合金能得到微米級的顆粒結構(粒度小于0.5μm)，而P類則不行。在磨耗方面，K類韌性更好，壽命更長。滾刀的重新刃磨和翻新滾刀加工一定數量的工件后，其切削刃變鈍，此時必須重新刃磨。刃磨后的滾刀必須保持原有的幾何形狀；切削刃必須鋒利；刀具的金相結構絕不可因磨削過熱而受破壞。因而在刃磨硬質合金滾刀時應采用一種油基冷卻液，它對氯和硫不起反應。對于刮削滾刀，刃磨后的重新涂層并不象用于實體毛坯硬滾的滾刀那樣重要。硬質合金滾刀刃磨后涂層前，建議對其刃口進行預處理。滾刀的重新刃磨將會除去切削表面的原有涂層，這會減少刀具壽命。刀具是可以重涂的。通常對于TiN涂層，可涂3～4次；對于TiCN和TiALN涂層而言，由于涂層本身有很大的內應力，所以在切削刃上難以再重新涂層。通過幾次涂覆TiN涂層后，會產生高低不均勻的狀況，并有分層脫落的傾向，所以原有涂層必須去除。目前有兩種方法可去除刀具涂層：化學退涂和物理退涂。用化學退涂去除硬質合金刀具上的涂層是一種精細工藝，要求操作者有相當的熟練程度。過度的化學退涂不僅將涂層去掉，而且還將溶洗鈷結合劑，損壞硬質合金材料的微觀結構。切削刃的微觀損壞將產生鋸齒狀表面。此外，在退涂時必須對滾刀軸臺、內孔及標志進行保護，以免損壞。而物理去涂，則必須由原刀具制造廠來進行，它涉及到整把滾刀齒形的重新磨削。雖然比化學退涂要貴得多，但得到的是一把新滾刀，質量和壽命都能得到保證。對滾齒機的要求為了充分發(fā)揮硬質合金和涂層工藝的優(yōu)點，滾齒機應作相應地改進。目前所有先進的滾齒機都按高速滾齒進行設計，其滾齒機的滾刀轉速超過3000r/min，通常為5000r/min，工件主軸轉速與滾刀轉速相匹配。此外，機床具有很高的動剛度和熱剛度。先進滾齒機的一些主要設計特點為：采用復合環(huán)氧樹脂床身，以改進機床的動態(tài)和靜態(tài)特性；帶有恒溫裝置的高速滾刀主軸箱；高速工件主軸；可采用干、濕二種滾削工藝；帶光電傳感器的數字驅動系統(tǒng)；直線滾動導軌系統(tǒng)；高速自動上料(2～3秒)；占地緊湊；按人機工程學設計；維修方便。采用刮削工藝無論是機械式的還是CNC的滾齒機都能進行刮削，但條件是機床必須裝備有工件到刀具的自動同步傳動系統(tǒng)。這可使刮削工藝更為經濟，對帶有自動上下料系統(tǒng)的機床也很重要。電子非接觸系統(tǒng)靠一個模擬量傳感器發(fā)出脈沖來測量刀具主軸、工件主軸和齒輪的位置。機床CNC控制器對這些脈沖進行處理，然后對工件主軸相對于刀具的位置進行調整，使工件輪齒和滾刀刀齒的相對位置關系正確。在刮削工藝中用冷卻液有很多優(yōu)點：在刮削過程中，冷卻液提供了潤滑性；由于刮削產生的不是正常的切屑，溫度控制極其重要。刮下的切屑較小較薄，不象正常刀屑那樣可帶走許多熱量，所以刮削時采用冷卻液可控制刀具、工件及機床系統(tǒng)的溫度；冷卻液可將切屑從刀具和工件上沖走；改善了工件表面精糙度；提高了刀具壽命。在“綠色滾削”工藝中，正確選擇齒厚余量是很重要的。推薦選擇順銑滾齒，因為它可得到最厚的切屑，這有助于控制切削過程的動態(tài)狀況，提高刀具壽命。經驗證明，切削速度可以超過200m/min，進給量的選擇取決于所要達到的表面光潔度。典型進給范圍為0.5～1.25mm/r。刀具移位(竄刀)的方法也很重要，因為刮削時只有粗加工截面的部分切削刃才經受磨損。相反，在“綠色切削”過程中，刀具的精加工部分承擔了主要加工量。這意味著在刮削時竄刀量應更大，如齒輪為12～48DP時，每次竄刀量為0.3～0.4mm。刮削滾刀的選取刮削硬質合金滾刀分為兩大類：用于10DP或更大模數的滾刀，通常都設計有一個負前角的切削前面，當切削刃接觸到淬硬齒面時，減小了對硬質合金材料的沖擊；對于較小模數的齒輪，就不需要有負前角。負前角的滾刀的缺點是刃磨困難。滾刀刃磨后外徑減小，為了得到正確的負前角就應改變砂輪的偏置量。當刮削中、大模數齒輪時，其齒頂、外圓直徑和齒根部位通常都不被滾削，并要求輪齒到齒根有一個平滑的過渡。為得到沉切和完整的過渡圓弧半徑，提高齒根的抗彎強度，用于大模數齒輪的理想刮削滾刀應帶有凸緣。對于小模數齒輪的加工，應采用標準滾刀。采用標準的徑向前角硬質合金滾刀加工稱為“硬質合金滾刀的再滾切”，而不是“刮削”，后者指的是采用了一個負前角滾刀。硬滾削的技術要求和硬刮削、或硬質合金滾刀再滾削的技術要求幾乎相同，不同之處是采用的竄刀移位的策略不同。在硬滾時，切屑的切除需花費大量能量。該能量最終變?yōu)闊崃?。設法把這些熱量散發(fā)帶走至關重要。建議每加工一個工件后，滾刀竄位一個全齒距。當滾刀從頭到尾竄位過后，應將滾刀移到離原始位置有一個偏置量的部位。該偏置量取決于滾刀的設計和應用，其目的是為了有助于滾刀的均勻磨損。另一不同之處是所采用的裝夾系統(tǒng)。由于極大的切削力，夾具必須安全夾緊工件。加工結果表明，同一斜齒輪用硬質合金滾刀再硬滾時，其齒輪質量很高，齒形接近AGMA10級，齒向和齒距超過AGMA12級；全淬硬毛坯硬滾切加工的斜齒輪，其齒輪精度也非常高，齒形精度可達AGMA10級，齒向和齒距可達到AGMA12級。結論已探索出許多經濟的方法來加工淬硬齒輪，包括材料的選擇、軟加工方法、熱處理工藝和硬精加工，使淬硬齒輪得到普及，滿足了高質量傳動裝置對淬硬齒輪的要求。個實體全淬硬工件毛坯進行淬硬滾切加工是一種新的加工工藝。由于有剛性更好的機床和優(yōu)質的硬質合金刀具材料并加以涂層處理，使淬硬滾切成為一種行之有效的加工方法。從工廠的實際應用結果表明，淬硬齒輪滾切(硬滾)工藝具有廣闊的應用前景。英文原文Hardgearprocessing[abstract]usesinthepowerdrivegearandthegearbox,itssizerequestsmaller,thegeardrivenoiseislower,thuscausestothehardgeardemand,alsogavethegearmanufacturertoproposeexploredthegeartoprocessthenewmethodtherequestOutlineUsesinthepowerdrivegearandthegearbox,itssizerequestsmaller,thegeardrivenoiseislower,thuscausestothehardgeardemand,alsogavethegearmanufacturertoproposeexploredthegeartoprocessthenewmethodtherequest.Thegearinthehardheattreatmentprocess,itsmaterialorganizationandthestresschange,usuallycancausethegeartohavethedistortion,namelytoothprofile,toothtoandtoothpitcherror.Thisthiserrorwillcausethetoothprofilenotcorrectlytomeshinthetransmissiontime,thushasenlargedtheload,willhavethegearnoise.Therefore,thehardgearaftertheheattreatment,shouldincreasetogethertheprecisionworkworkingproceduregenerally.Thehardgearprecisionworkcraftmaydivideintotwokinds:Akindisusesnon-formedthecuttingedge,likethegearrubstruncatestheprocessing;Anotherkindthenishasformedthecuttingedgelikehardgear(HRC48~53)torolltruncatestheprocessing.Thisarticlestronglywilldiscusswilluseinhardlyrollingthehardalloytoolsformingcuttingedgeprecisionworkprocesswhichthetoothwillprocess.Thenowhardalloymaterial,thecuttingtoolcoatingandthegear-hobbingmachinetechnologydevelopment,hascausedthehardgeartorollcutstheprocessingtechnologytohavetheremarkableenhancement,speciallyissmallerthanintheprocessingorwasequaltowhen12DPcentersmallmodulusgear,maywithstandtheenormouscuttingforcewhichinthehardcuttingprocessproduces.HardalloyhobselectionThehardalloyhobhastheverybigprogressinthematerialvarietyspecification.Superfine,isthin,mediumorthebigpellethardalloynowallhastheproduct.Inaddition,thehardalloyhobsemifinishedmaterialsformedcrafttechnologyalsohadtheremarkableenhancement,likeusesstaticpressureandsoonheat(HIP)thecraft,thiscraftunderthehigh-pressuredhightemperature,increasedthehardalloysemifinishedmaterialsintrinsicbindingforce,enhancedthehardalloyanti-curvedintensity.AccordingtotheISOstipulation,theentityhardalloymaterialmaydifferentlydivideintocertainkindsaccordingtotheapplicationsituation:ThegearcuttingtooldividesintoKkindandPkind,Kkindofhardalloyhasahigherresistancetowear,Pkindthenhasthebetterhightemperatureredhardness.IntheKtrademarkandinthePtrademarkhardalloy,eachkindoftrademarkhardalloygranularstructureisdifferent,frommediumpellettosuperfinepellet.Eachkindoftrademarkallhasitsapplicationsituation,thisisandthegranularstructureisconnected.Generallyspeaking,regardingsoftlyrollstruncates,theKanalogyPkindofperformanceisfriendswith,Kkindofhardalloycanobtainamicronlevelthegranularstructure(granularitytobesmallerthan0.5mum),butPkindthenisnotgood.Inabrasionaspect,Kkindoftoughnessbetter,thelifeislonger.ThehobresharpensandrenovatesAfterthehobprocessingcertainquantityworkpiece,itscuttingedgefailure,thistimemustresharpen.Sharpenstheafterhobtohavetomaintaintheoriginalgeometryshape;Thecuttingedgemustbesharp;Thecuttingtoolgoldenphasestructurecannotbecauserubtruncatestheheatbuttodestroy.Thuswhensharpensthehardalloyhobshoulduseonekindofoilbaserefrigerant,itdoesnotgetuptothechlorineandthesulfurtheresponse.Regardingscrapesthehob,sharpensafterthecoatingnotlikelytouseinhobsuchwhichtheentitysemifinishedmaterialshardlyrollsbeingimportantagain.Afterthehardalloyhobsharpensinfrontofthecoating,suggestedcarriesonthepretreatmenttoitscuttingedge.Thehobrewillsharpencanexceptthecuttingsurfaceoriginalcoating,thiswillbeabletoreducethecuttingtoollife.Thecuttingtoolismayagainspread.UsuallyregardingtheTiNcoating,mayspread3~4;SaysregardingTiCNandtheTiALNcoating,becausecoatingitselfhastheverybiginternalstress,thereforeoncuttingedgewithdifficultyagainagaincoating.AfterseveralspreadingTiNcoating,canhavetheheightnon-uniformitycondition,andinfluentialsthetendencywhichthelevelfallsoff,thereforetheoriginalcoatingmustremove.Atpresenthastwomethodstobepossibletoremovethecuttingtoolcoating:Chemistrydrawsbackspreadsdrawsbackwithphysicsspreads.Drawsbackwithchemistryspreadsremovesonthehardalloytoolsthecoatingisonekindoffinecraft,requeststheoperatortohavethesuitablelevelofexpertise.Theexcessivelychemistrydrawsbackspreadsnotonlyremovesthecoating,moreoveralsowilldissolvewashesthecobaltcement,thedamagehardalloymaterialmicroscopicstructure.Thecuttingedgemicroscopicdamagewillproducethezigzagsurface.Inaddition,whendrawsbackspreadsmusttothehobpillowblock,intheholeandthesigncarriesontheprotection,inordertoavoiddamages.Butphysicsspreads,thenmustcarryonbytheoriginalcuttingtoolfactory,itinvolvestoputsinorderrerubsthehobtoothprofiletruncates.Althoughdrawsbackchemistryspreadsmustbemuchmoreexpensivethan,butobtainsisanewhob,thequalityandthelifeallcanobtaintheguarantee.Togear-hobbingmachinerequestInordertofullydisplaysthehardalloyandthecoatingcraftmerit,thegear-hobbingmachineshoulddocorrespondinglyimproves.Atpresentalladvancedgear-hobbingmachinesallpresshighspeedrollthetoothtocarryonthedesign,itsgear-hobbingmachinehobrotationalspeedsurpasses3000r/Min,usuallyis5000r/Min,theworkpiecemainaxlerotationalspeedandthehobrotationalspeedmatch.Inaddition,theenginebedhasveryhighmovestherigidityandthehotrigidity.Theadvancedgear-hobbingmachinesomemaindesigncharacteristicsare:Usesthecompoundepoxyresinlathebed,byimprovestheenginebedthetendencyandthestaticcharacteristic;Hastheconstanttemperatureinstallmentthehighspeedhobheadstock;Highspeedworkpiecemainaxle;Mayusedoes,thewettwokindsrollstruncatesthecraft;Beltelectro-opticalsensordigitalactuationsystem;Thestraightlinerollstheguiderailsystem;Highspeedautomatichigh-qualitygoods(2~3seconds);Theoccupyingalandareaofiscompact;Accordingtoman-machineengineeringdesign;Servicesconveniently.UsesscrapesthecraftRegardlessofisthemechanicaltypetheCNCgear-hobbingmachineallcancarryonscrapes,buttheconditionistheenginebedmustequiphastheworkpiecetothecuttingtoolselsyntrainsystem.Thismaycausetoscrapethecrafteconomically,tohasontheautomaticyummytreatssystemtheenginebedverytobealsoimportant.Theelectronicnon-contactsystemdependsonasimulationquantitysensortosendoutthepulsetosurveythecuttingtoolmainaxle,theworkpiecemainaxleandthegearposition.TheenginebedCNCcontrollercarriesonprocessingtothesepulses,thenisoppositetotheworkpiecemainaxleinthecuttingtoolpositioncarriesontheadjustment,causesaworkpieceturnoftoothandthehobknifetoothrelativepositionrelationsiscorrect.Inscrapesinthecrafttohaveverymanymeritswiththerefrigerant:Inscrapesintheprocess,therefrigeranthasprovidedthelubricatingability;Becausescrapesproducesisnotthenormalscrap,thetemperaturecontrolisextremelyimportant.Blowsthescrapsmallisthin,doesnotlooklikenormalknifefilingssuchtobepossibletocarryoffmanyquantityofheats,thereforescrapestimeusestherefrigeranttobepossibletocontrolthecuttingtool,theworkpieceandtheenginebedsystemtemperature;Therefrigerantmaywashesawaythescrapfromthecuttingtoolandtheworkpiece;Improvedtheworkpiecesurfacefineroughness;Enhancedthecuttingtoollife."Rollsinthegreentruncates"inthecraft,correctlychoosesthetooththickremainderisveryimportant.Therecommendationchoicedownmillingrollsthetooth,becauseitmayobtainthethickestscrap,thisishelpfultothecontrolcuttingprocessdynamiccondition,enhancesthecuttingtoollife.Theexperienceprovedthat,thecuttingspeedmaysurpass200m/Min,entersforthequantitychoiceisdecidedbythesuperficiallyattractivefinenesswhichmustachieve.Themodelentersforthescopeis0.5~1.25mm/R.Thecuttingtoolshifts(fleesknife)themethodverytobealsoimportant,becausescrapestimeonlythentheroughmachiningsectionpartialcuttingedgesonlythenundergotheattrition.Onthecontrary,in"thegreencutting"intheprocess,thecuttingtoolprecisionworkhaspartiallyundertakenthemainprocessload.Thismeantwhenscrapingfleestheknifequantitytobesupposedtobebigger,whenlikethegearis12~48DP,eachtimefleestheknifequantityis0.3~0.4mm.ScrapesthehobtheselectionScrapesthehardalloyhobtodivideintotwobigkinds:Usesin10DPorthebiggermodulushob,usuallyalldesignshasanegativerakefrontthecutting,whenthecuttingedgecontactstothehardtoothface,reducedtothehardalloymaterialimpact;Regardingthesmallmodulusgear,doesnotneedtohavethenegativerake.Thenegativerakehobshortcomingissharpensthedifficulty.Afterthehobsharpenstheouterdiametertoreduce,inordertoobtainthecorrectnegativeraketobesupposedtochangethegrindingwheelthebiasquantity.Whenscrapes,thebigmodulusgear,itsaddendum,theouterannulusdiameterandthetoothrootspotallareusuallynotrolledtruncates,andhasasmoothtransitionarequestturnoftoothtothetoothroot.Inordertoobtainsinkscutswiththeintegritytransitioncirculararcradius,enhancesthetoothroottheanti-curvedintensity,usesinthebigmodulusgearidealscrapingthehobtobesupposedtohavetheflange.Regardingthesmallmodulusgearprocessing,shouldusethestandardhob.Usesthestandardinfrontoftheradialdirectiontheanglehardalloyhobprocessingtobecalled"thehardalloyhobtorollagaincuts",butisnot"scrapes",latterreferredhasusedanegativerakehob.Hardlyrollsthespecificationwhichtruncatesandhardlyscrapesthespecificationwhich,orthehardalloyhobrollsagaintruncatesnearlysame,similarityisusesthestrategywhichfleestheknifetoshifttobedifferent.Whenhardlyrolls,thescrapexcisionmustspendthemassiveenergies.Thisenergyfinallybecomesthequantityofheat.Triestocarryoffveryimportantthesethermalsendingout.Afterthesuggestionprocessesaworkpieceeverytime,thehobfleesapositionentiretoothpitch.Whenthehobwillfleefrombeginningtoendthepositionfromnowon,willbesupposedtotransfertothehobtotheinitialpositionhasabiasquantity