1、10FTM01AGMA Technical PaperComplete Machiningof Gear Blank andGear TeethBy Dr.-Ing. C. Kobialka,Gleason-PfauterComplete Machining of Gear Blank and Gear TeethDr.-Ing. Claus Kobialka, Gleason-PfauterThe statements and opinions contained herein are those of the author and should not be construed as an
2、official action or opinion of the American Gear Manufacturers Association.AbstractDemands for increased throughput, with smaller lot sizes at lower cost have led to the development of aninnovative approach to machining both: the gear bland and gear teeth on a single machine.This paper will concentra
3、te on the potentials and risks of combined process machines what are capable ofturning,hobbing,drilling,milling,chamferinganddeburringofcylindricalgears. Thesamemachineconceptcan be used for singular operations of each manufacturing technology on the same design concept. Thisleadstoreducedamountsofd
4、ifferentspareparts,increasesachievableworkpiecequalityandharmonizesonacommonuserfriendliness. Intheendtheeconomicalpotentialofcombinedprocesstechnologyandavisionfor integrated heat treatment is shown.Copyright 2010American Gear Manufacturers Association500 Montgomery Street, Suite 350Alexandria, Vir
5、ginia, 22314October 2010ISBN: 978-1-55589-976-93Complete Machining of Gear Blank and Gear TeethDr.-Ing. Claus Kobialka, Gleason-PfauterIntroductionOver the past years a large number of differentmachine tool builders have shown a tendency forcombination of different processes into onemachine 1. The b
6、enefitand thelimitations ofsuchaconceptincludinggearingprocessesischaracter-ized by technical, commercial and local impacts.Increased flexibility and shortening down of leadtimes are the main driving factors of suchdevelopments.Productivity in soft gearing processesDue to increased flexibility reque
7、sts on industrialserial production today batch sizes are decreasing2. In parallel the part complexity and the reques-ted workpiece quality is increasing. For meetingboth requeststhe processchain hasto beanalyzedfor shortening set up times (Figure 1).In general the gear production of a forged or sawe
8、dblankpartischaracterizedbysubsequentmanufac-turing processes like turning, milling and/or drilling,hobbing and in most applications a rotary chamfer-ing and deburring before heat treatment (Figure 2).Added by washing and marking operations asoptional operations there are at least 5 differentoperati
9、ons in the green stage for dry machining ageared workpiece 3,4. Due to wet cutting, thedemand on washing/cleaning and additional opera-tions there are existing up to 12 differentoperationsin gear manufacturing in todays green stageproduction. The focus of process optimization wasin a first step the
10、concentration on the 5 mostimportant process technologieslike turning,milling,drilling, hobbing and chamfering/deburring.Figure 1. Why combination technology?4Figure 2. Process chain in gearingThe so-called combination technology is based ona restructure of theexisting processchain. In afirststep a
11、common machine platform for all thisdifferent manufacturing technologies had to beidentified. This was realized by a L-formed mineralcast installation rack. Based on that a broad rangeof different subassembly components for continu-ous and interrupted cutting has to be added(Figure 3). In most cases
12、 the subassemblycomponenthastomeetdivergentrequestsandwiththat come associated compromises. Oneexamplefor that is the work piece drive. For turning a hightorque capacity in combination of highest rpm-capabilityisstateoftheart. Forgearoperations,forexample, hobbing or shaping a high level ofcontinuou
13、s rotary movement is necessary. Formeeting both characteristics the torque capacity ofwell known turning spindles had to be reduced byfactor three. In parallel a universal interface fordifferent subassembly groups on the machine plat-form and installation basis had to be identified andto be realized
14、. This standardization will ensure infuture that on the same platform additional manu-facturing technologies will be implemented or cansubstitute different configurations, based onapplications needed of technology enhancements.Figure 3. What is combination technology?5As a result on that concept the
15、 total duration of aworkpiece that is remaining in different machines isreduced by the red marked idle times (Figure 4). Indaily production not all operations are optimized toone common time. In addition to that every opera-tions shows a smaller or larger stock or queue ofworkpieces in front of any
16、machine, so that a largerthan necessary amount of workpiece material isstored in the production line. This is impactinglogistic efforts and costs as well as the workingcapital by the amount of workpiece material that isstored semi finished in the production line. Alongwith workpiece materials in dif
17、ferent stages of theproduction lines, quality of the process has to beconsidered. Thisisduetothedifferentfeaturesandworkpiece clamping features change from turningto gearing operations.One additional aspect is the workpiece quality. Insubsequent operations the turned bearing seat isnot perfect adjus
18、ted to the gear due to a change inworkpiece clamping between turning and hobbingoperation.As mentioned in Figure 1, a broad range of work-piecesiscapableforcombinationtechnology. Intheshownexampleafirstfocusisrelatedto shafttypedgear production (see Figure 5). Due to the limitedno. of tool places on
19、 the turret a lengthening andcentering operation is requested before loading theshaft typed workpiece to a machine that is capablefor combination technology.Figure 4. Benefits of multiple manufacturing in one clampingFigure 5. Workpieces for combined process technologies6Based on that, external part
20、 geometries andfeatures can be manufactured.Lengthening and centering of shaft typedworkpieces. For disk typed workpieces a corres-ponding driven tailstock with a special solution ofworkholding equipment is necessary.Combination technology combines differentmanufacturing technologies into one numeri
21、calcontrol (Figure 6 and Figure 7). Due to the highnumber of operations and machine functions, themachinist has to have a high level of machine andprocess understanding. Turning is not hobbing,chamfering and deburring is not milling or drilling.This high request on experience and skill brings upthe
22、question of the level of skill and the area ofmarket, where such a technology that will besuccessful installed.Figure 6. Process Analysis for shaft typed workpieceFigure 7. Process Analysis for disc typed workpiece7Based on individual skills the combination techno-logy is a high end request on a mac
23、hinist s experi-ences and skills. Based on local documented skillsof production employees and an analysis of thatshowsthatcombinationtechnologywillensurepos-itive impacts to the higher salary areas of the world.In Asia-Pacific-region the labor costs for human re-sources and footprint of a machine wi
24、ll show signi-ficant benefit for well known, old structuredprocesschains (see Table 1).Table 1. Labor cost comparisonCountryLabor costper year per hourChina $1.70 $1.35India 1.45 $1.15West Europe $70.00 $55.55Americas $65.00 $51.58At the highercost levels,like thesituation inEuropeand North America,
25、 the combination technologyshows beneficial characteristics.Infuturetheinductiveheattreatmentofgears,bear-ing seats and other relevant items on a work piecewill reorganize and reduce the manufacturing ef-forts of geared work pieces. Today the carburizingheattreatmentprocessissubdividingthegearman-uf
26、acturingprocessintotwodifferentsections. Afirstsoftorientedpartandafterwardsasecond,hardfin-ish manufacturing sequence. The continuous flowofmaterialofeach,softandhard,areinterruptedbythe carburizing process. By implementation of theinductive hardening process a change of the todayused work piece ma
27、terials will be necessary. In ad-dition to that the soft manufacturing strategy will beimpacted by longer cycle times and reduced lifetimes to the used tools.Thegreatchancewillbeainlineheattreatmentwithcompetitive work piece behaviors in comparison tothe carburizing process. First applications of ge
28、arsshow a well working performance on that, seeFigure 8.SummaryMain manufacturing technologies in gearing areturning,hobbing,chamferinganddeburring. Inseri-al and mass production of gears the direct linkeduse of singular processes is state of the art.In parallelto optimizationof eachprocess theinteg
29、-ration of different processes shows a high potentialforreductionoftheleadtimeaswellasanincreasedlevel of work piece quality. Reduction of productionprocess complexity and peripheral investments forautomation systems increase the economical as-pect of such efforts.Figure 8. Inductive hardened gear8T
30、he discussion of local based human costs, the in-tegrationofheattreatmentandinfinalthepossibilityforinlineinspectionofgearsensuresapossibilityforhigh level gear production.Final the complete machining of gear blank andgear teeth will impact manufacturing strategies infuture.References1. Statistische
31、s Bundesamt/VDMA2. Klaiber, M., “Maschinen- und Anlagenbau Quo Vadis?” Lehrgang Praxis der Zahnrad-fertigung, Technische Akademie Esslingen,20093. Westkmper, Balve, Wiendahl, Auftragsman-agement in wandlungsfhigen Un-ternehmensstrukturen“ PPS-Management,20084. Abele, N., “Wandlungsfhige Produktion-sprozesse”, Diskussionsforum, IWB, TUMnchen, 2008
