欢迎来到麦多课文档分享! | 帮助中心 海量文档,免费浏览,给你所需,享你所想!
麦多课文档分享
全部分类
  • 标准规范>
  • 教学课件>
  • 考试资料>
  • 办公文档>
  • 学术论文>
  • 行业资料>
  • 易语言源码>
  • ImageVerifierCode 换一换
    首页 麦多课文档分享 > 资源分类 > PDF文档下载
    分享到微信 分享到微博 分享到QQ空间

    AGMA 12FTM10-2012 Development of Novel CBN Grade for Electroplated Finish Grinding of Hardened Steel Gears.pdf

    • 资源ID:422155       资源大小:599.04KB        全文页数:13页
    • 资源格式: PDF        下载积分:5000积分
    快捷下载 游客一键下载
    账号登录下载
    微信登录下载
    二维码
    微信扫一扫登录
    下载资源需要5000积分(如需开发票,请勿充值!)
    邮箱/手机:
    温馨提示:
    如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
    如需开发票,请勿充值!如填写123,账号就是123,密码也是123。
    支付方式: 支付宝扫码支付    微信扫码支付   
    验证码:   换一换

    加入VIP,交流精品资源
     
    账号:
    密码:
    验证码:   换一换
      忘记密码?
        
    友情提示
    2、PDF文件下载后,可能会被浏览器默认打开,此种情况可以点击浏览器菜单,保存网页到桌面,就可以正常下载了。
    3、本站不支持迅雷下载,请使用电脑自带的IE浏览器,或者360浏览器、谷歌浏览器下载即可。
    4、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰。
    5、试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。

    AGMA 12FTM10-2012 Development of Novel CBN Grade for Electroplated Finish Grinding of Hardened Steel Gears.pdf

    1、12FTM10AGMA Technical PaperDevelopment of NovelCBN Grade forElectroplated FinishGrinding of HardenedSteel GearsBy U. Sridharan, S. Ji,S. Kompella and J. Fiecoat,Diamond InnovationsDevelopment of Novel CBN Grade for Electroplated FinishGrinding of Hardened Steel GearsUppili Sridharan, Shuang Ji, Srid

    2、har Kompella and James Fiecoat, DiamondInnovationsThe statements and opinions contained herein are those of the author and should not be construed as anofficial action or opinion of the American Gear Manufacturers Association.AbstractThe unique requirements of an electroplatable superabrasive CBN gr

    3、it used in profile grinding of hardenedsteel gears as well as the attributes and grinding behavior of a new CBN developed specifically for thisapplication are discussed. Profile gear grinding parameters were simulated in through-hardened AISI 4140steel(56HRC)andthegrindingperformanceofthenewCBNwasco

    4、mparedagainstacompetitiveCBNgradewidely used in the application. Consistent with field criteria, grinding performance was characterized basedonoccurrenceofburnorformfailure. Theburnormetallurgicalphasetransformationfailurewasdetectedby Barkhausen Noise Analysis (BNA) and corroborated by microstructu

    5、ral and microhardness evaluations.The form failure was simulated by tracking average radial wheel wear to a threshold value where form losswas expected to occur. Grinding tests indicate that the new CBN grit can grind 35% more parts compared tothe competitive CBN grade before burn failure. In additi

    6、on, the new CBN displayed a lower wear rate. Thenew CBN grade also exhibited a uniqueability to grind with lower grinding power,resulting ina nearconstantBNAresponseonthegroundsurfacethroughoutthetest. Thisimpliedminimalmicrostructuralchangeonthegroundpartfromstarttoendofthetestcomparedtotheprogress

    7、ivesofteningofgroundsurfacenoticedwiththe competitive CBN.Copyright 2012American Gear Manufacturers Association1001 N. Fairfax Street, Suite 500Alexandria, Virginia 22314October 2012ISBN: 978-1-61481-041-43 12FTM10Development of Novel CBN Grade for Electroplated Finish Grinding of HardenedSteel Gear

    8、sUppili Sridharan, Shuang Ji, Sridhar Kompellaand James Fiecoat, Diamond InnovationsINTRODUCTIONGears are the most common power transmission devices used in a wide range of applications likeautomobiles,powergenerationandmachinetools. Dependingontheirusage,gearscanbequalitativelyclas-sified as commod

    9、ity gears and precision gears. Commodity gears usually are small gears with minimal loadcyclesandgeometricaltolerancesrequirements. Precisiongearswhichareusedinhigh-endaerospaceandautomotive applications have ever increasing requirements imposed on them. These include increasedservicelife,lowerNVHle

    10、vels,minimizedbacklashesandabilitytoaccuratelypredictservicelifeforpreventivemaintenance 1.Such stringent requirements have naturally had an influence on manufacturing and process control of preci-siongears. Thepasttwodecadeshasseenasteadyriseindemandforgearstobehardfinishedbymachiningor grinding to

    11、 achieve the above mentioned performance metrics. Gear manufacture begins with formingprocesseslikeforgingorblankmachiningprocesseslikehobbing. Thisisfollowedbyheattreatingprocessessuch as case carburizing, through hardening, and nitriding. The heat treating process induces distortions inthe gear wh

    12、ich necessitate hard finishing as the last step to ensure maximum load capacity and reducedtransmission noise 2.Hardfinishingiseitherdonebymachiningprocesswithdefinedcuttingedgeslikeskivehobbing,hardturning,etc or by abrasive finishing processes like grinding or gear honing 2. The classification of

    13、abrasivefinishingprocesses is as shown in Figure 1 2.Thegrindingprocessesusedinfinishgrindingofhardenedgearscanbeclassifiedasgeneratinggrindingandprofilegrindingdependingonhowtheprofilesofgeartootharefinished. Thegrindingprocesscanbecontinu-ous where the gear profile is achieved progressively by gri

    14、nding with a splined wheel or discontinuous profilegrinding where a specific profile is ground one gear tooth at a time.Figure 1. Breakdown of abrasive hard finishing processes 24 12FTM10Continuous generating grinding is typically adopted when grinding small batches with varying gear profilesandhenc

    15、eusedressableconventionalaluminumoxidewheelsintowhichprofilescanbeeasilydressedusingadiamonddressingtool. Incertainspecialcaseswheremaintaininggearsurfaceintegrityisimportantvitrifiedbonded CBN wheels may be preferred over conventional vitrified wheels 3.Discontinuousprofilegrindingisgenerallyusedin

    16、ahighvolumerepetitiveprocessandtypicallyusesanelec-troplatedsuperabrasiveCBN wheel. ElectroplatedCBN wheelscontain asingle layerof abrasiveembeddedin a nickel matrix and have the negative profile of the gear tooth ground with abrasive protrusion tolerancetypicallylessthan5mm. Thisisessentialtoachiev

    17、eaccurateprofileoneachgeartoothduetothesinglepassnature of the process.This paper focuses on the unique requirements, physical attributes and grinding performance of a develop-mental grade of CBN designed specifically for electroplated profile grinding process.Profile Grinding CBN lDue to the nature

    18、 of the grinding process itself and also the type of bond system used in the wheels, the re-quirements of a CBN grit used in an electroplated profile grinding wheel differs from a CBN grit typeused inavitrified bonded CBN wheel for other applicationsVitrified bonded wheels are characterized by high

    19、natural porosity a multiple grit layers held together by theglass frit in the bond. Hence physical properties of a CBN such as shape and toughness only partially influ-encetheperformancemetricsofthewheelsuchasabilitytomaintainform,grindwithlowpowertoreduceriskofpartburnandgreaterintervalsbetweenwhee

    20、lreconditioning. Incontrast electroplatedwheels exhibithighabrasive protrusion with 40-50% of the abrasive embedded in a non-porous nickel matrix. This is one oftheprimaryreasonswhyelectroplatedwheelswork bestin aprofile grindingset upas thehigh levelof gritprotru-sion enables high material removal

    21、rates enabling fewer grinding strokes per tooth while achieving the re-quired gear form. Because of this, the physical properties of CBN grit have a greater influence on the wheelperformance in an electroplated wheel than a bonded wheel.CBNgritsusedinanelectroplatedwheel aretypically highlyblocky in

    22、shape withaverage aspectratios oftheparticleslowerthan1.50topromoteuniformwheelwear. TheyarealsomuchtougherthantheCBNgritsusedin a bonded wheelto ensurelong wheellife. The rangeof materialremoval ratesused inprofile geargrindingapplicationresultsintheCBNcrystalwearbeingmoreattritiousthaninotherappli

    23、cations. ThustheCBNgritstendtobecomeprogressivelydullwithwheelusage resultingin anincrease ingrinding powerand theassoci-ated risk of thermal damage.Ingeargrinding,wherethermaldamageadverselyaffectsthelifeandperformanceofthegear,itisimperativeto use a CBN which exhibits a tendency to fracture in sma

    24、ll fractions and thus keeping the wheel sharp andfree cutting with a stable grinding power. This property is termed as “microfracturing” capability. It is alsohighlydesirabletohaveahighlyblockyshapetopromoteuniformwheelweartoachieveconsistentgeartoothform from the start to the end of grindingwheel l

    25、ife. Achievinga uniformwheel wearin profilegear grindingisparticularly challenging as the depths of cut and corresponding grinding forces encountered by the grits varycontinuouslyfromthetoptobottomofageartoothflankascitedinpreviousattemptstomodelgrindingforcesin profile gear grinding 2.The requireme

    26、nts of CBN crystals with uniform shape and lower toughness are truly unique to profile geargrinding. Generally, CBN crystal shapes and toughness are directly correlated i.e. more uniform crystalspossesshighertoughnessandviceversa. Thusdeveloping acrystal withlower toughnessand blockyshapepresents si

    27、gnificant technical challenges. Development of such a novel CBN referred henceforth asDevelopmental CBN A is reported here along with grinding performance compared to a competitive CBNgrade that is commercially available and used in this application.CBN morphology and characterizationVisually, CBN A

    28、 has much rougher, less well defined facets than the competitive CBN as seen from SEMmicrographsinFigure 2. Theroughsurface morphologyhelps promotemicrofracturing abilityin thecrystals.5 12FTM10Figure 2. Comparison of crystal morphologyCBN crystals are generally characterized as a function of their

    29、friability using a metric known as ToughnessIndex (TI). It is a composite measure that takes into account the hardness, shape and fracture behavior of acrystal. The procedure entails placing a precisely measured amount of CBN in a capsule of pre-defined in-ternalgeometryalongwithatungstencarbideorst

    30、eelball. Theclosedassemblyisvibratedatasetfrequencyfor a fixed amount of time. The contents of the capsule are then separated using a sieve stack and the CBNcollected in the sieve stack is accurately weighed. The ratio of the weight of CBNthat resistedfracture tothestarting weight is reported as the

    31、 TI. Figure 3 shows that the normalized TI of CBN A relative to competitiveCBN A is similar.ExperimentalTypicalgeargrindingprocessrunsatwheelspeedsof25-30m/swithstraightoillubricationanddepthsofcutof 0.25 mm or lower. A laboratory-scale grinding test configuration, described below, was designed tofa

    32、ithfully capture gear grinding conditions as closely as possible.Figure 3. Relative crystal toughness index6 12FTM10Gear grinding simulation test descriptionProfile gear grinding simulation tests were conducted using 1A1 electroplated wheels containing US mesh170/200(B91)gritofDevelopmentalCBNAandth

    33、eCompetitiveCBN. Thewheelspecificationsareasbelowin Table 1. Twowheels ofeach abrasivetype werefabricated andtested toassess wheelto wheelvariability.Through hardened AISI 4140 steel which is a commonly used gear material was chosen as the workpiecematerial. The 4140 workpieces were chosen to be 3.2

    34、 mm in thickness to ensure uniform throughhardenability. The specifications of the 4140 workpiece used for the tests are provided in Table 2.SurfacegrindingtestsweredoneusingaBlohmPrecimat306surfacegrinderwithdepthofcutof0.127mminupcutmodesimilartodepthsofcutsadoptedinprofilegeargrinding. Awheelspee

    35、dof45m/swasusedalongwith a 5%-concentration water soluble oil coolant at a flow rate of 151 liters/min at the entry and exit of cut.This wheel speed was chosen to reduce wheel wear when using a water soluble coolant.Performance metricsThetwoprimarymetricsbywhichtheperformanceofageargrindingwheelisas

    36、sessedaretheriskofthermaldamageandlossofforminthegroundgear. Theoccurrenceofeitheronthegroundgearwouldbeconsideredthe point of wheel failure. To capture these aspects, grinding performance in the simulation tests was meas-ured as a function of radial wheel wear, surface finish, and specific grinding

    37、 energy. In addition, the thermalimpactofgrindingontheworkpiecewasmeasuredbyBarkhausenNoiseAnalysis(BNA). Awearthresholdof30 mm of wheel wear was chosen to correspond to “form failure”. The radial wheel wear and surface finishweremeasuredbyaHommelWaveline60stylus-basedprofilometer. Thewheelwearwasre

    38、plicatedinasoftsteelcouponwiderthanthewidthofgrindingasshowninFigure 4. Thoughthe wheelwas 12.5mm wide,thewidth of cut was maintained at 3.2 mm. Thus only a portion of the wheel width was used for one test. Thisenabled use of the wheel for a second test if needed. The un-used portion of the wheel wa

    39、s used as areference surface from which to monitor wheel wear. After a pre-determined volume of the material wasground, the entire width of the wheel was used to take a shallow cut in a soft steel workpiece. The resultantwheel trace on the soft steel block was recorded using a stylus-based profilome

    40、ter. Such a trace provided ameasure of the wheel wear relative to the un-used (reference) wheel.Table 1. Wheel specificationsWheel type Electroplated 1A1Wheel diameter 152 mm (6.0 in)Wheel width 12.5 mm (0.50 in)Mesh size US Mesh 170/200 (B91)Table 2. Grinding test conditionsMachine Blohm Precimat 3

    41、06, 15 hp CNC surface grinderGrind mode Transverse (upcut only)Test material AISI 4140 steel; through hardened to 54-56 HRCWorkpiece heat treating conditions Austenitized at 1575F for 45 minutesTempered at 325F for 2 hoursWheel speed, vs45 m/s (9,000 SFPM)Depth of cut, ae0.127 mm (0.005 in)Width of

    42、cut, bd3.2 mm (0.126 in)Length of cut, lc305 mm (12 in)Specific material removal rate, Q/w 8.1 mm3/mm/s (0.75 in3/in/min)Table speed, vw3.8 m/min (150 ipm)Coolant Water soluble oil at 5% concentrationCoolant flow 151liters/minat6.9bar(40gpmat100psi;entryandexit nozzles)7 12FTM10Figure 4. Illustratio

    43、n of radial wheel wear measurementItmustbenotedthatforUSmesh170/200,wheretheaverageCBNgritsizeis91mm,thenominalcoverageofnickel layer for electroplating is 40-50% of the mean grit size. Thus, in theory an electroplated wheel with170/200 mesh particles is expected to perform predictably to a wheel we

    44、ar of at least 45 mm. Hence a wearthreshold of 30 mm is very rigorous for the purpose of gauging form failure in actual gear grinding process.The specific grinding energy was quantified by monitoring spindle power using a Hall-effect transducer TheBarkhausenresponseofthegroundworkpiecewasalso record

    45、ed. TheBarkhausen NoiseAmplitude forthe4140steelworkpiecetypewasoptimizedtodetectgrindingburnasdiscussedinthesectionbelow. Theover-all effective wheel life was determined by the quantity of material ground at the point of occurrence of either“burn failure” as established by BNA or “form failure.”Bar

    46、khausen Noise AnalysisBarkhausenNoiseAnalysisisanon-destructivemethodofevaluatingsurface integrityby detectingchangesin microstructure in ferromagnetic materials. Barkhausen noise is an inductively measured magneto-elasticsignal from ferromagnetic materials which consists of small magnetic regions c

    47、alled “magnetic domains”which act like microcosmic magnets. These domains are separated by boundaries known as domain wallswhich rotate the magnetic vector of the domains 4.Whenan externalmagnetic fieldis applied,it initiatesan alternateorientation ofthe magneticdomains bythemovementofthedomainwalls

    48、. Thischangeinorientationisstepwiseduetoirregularchanges ofmagnetiza-tion. The removal of the exciting magnetic field causes reversal of domain wall movements, but some do-mains are not able to take their original dimension and orientation due to a hysteresis phenomenon 4.This property of ferromagne

    49、tic materials can be taken advantage of by applying an alternating current whichwould result in back and forth movement of the domains walls which can be measured and expressed asBarkhausen Noise Amplitude.BNA Optimization ProcedureSeveral workpiece properties such as the chemical composition, heat treating methods and conditions influ-ence a material s response to Barkhausen Noise Analysis and have been discussed in detail elsewhere4.Thus the excitation field conditions (voltage, frequency and amplitude filter) have to be optimized for


    注意事项

    本文(AGMA 12FTM10-2012 Development of Novel CBN Grade for Electroplated Finish Grinding of Hardened Steel Gears.pdf)为本站会员(sumcourage256)主动上传,麦多课文档分享仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文档分享(点击联系客服),我们立即给予删除!




    关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

    copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
    备案/许可证编号:苏ICP备17064731号-1 

    收起
    展开