墻壁式旋臂起重機(jī)結(jié)構(gòu)設(shè)計(jì)【三維SW】【含6張cad圖紙+文檔全套資料】

喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請(qǐng)放心下載，，有疑問(wèn)咨詢(xún)QQ:414951605或者1304139763 ======================== 喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請(qǐng)放心下載，，有疑問(wèn)咨詢(xún)QQ:414951605或者1304139763 ======================== ORIGINAL ARTICLEState-of-the-art on vibratory finishing in the aviation industry:an industrial and academic perspectiveR. Mediratta1&K. Ahluwalia1&S. H. Yeo2Received: 25 May 2015 /Accepted: 4 October 2015# Springer-Verlag London 2015Abstract Vibratoryfinishingisaversatileprocessthatisusedin many industries globally for radiusing, brightening,deburring, fine finishing, cleaning, burnishing, and descalingof components. This state-of-the-art paper will discuss howvibratory finishing has evolved into what it is today and theadvancements in technology. The development of massfinishing, the importance of vibratory finishing in aviationindustry, the parameters involved in this process, and the pat-ent landscape of the advancements in vibratory finishing willbe elucidated. More importantly, the paper will dwell intoattempts made to understand the science behind this arcaneprocess. Empirical investigations, model developments, bulkand granular impact velocity studies, vibrostrengthening, andAlmen strip characterization are the research efforts that willbe discussed in particular. This work has identified gaps in thevibratory finishing process, some of them being media flowmeasurement and the need for a monitoring system to deter-mine the frequency losses from motor vibrations to the mediavibrations. Methods for calculating the frequency and ampli-tude of machine vibrations, the impact velocity of media, andthe force of media striking the workpiece are still under re-search. Literature points out that more work can be done interms of the quantification of process parameters, the relation-ship between them, and the effect they have on the surfacefinish. The industry is on the lookout for shorter cycle timeswithimprovedsurfacefinishingquality,andthusvarioustech-nological advancements in vibratory finishing, namely dragandspindlefinishing,havecomeintoexistence.Totheknowl-edge of the authors, there has been no comprehensive reviewworkdoneonvibratory finishing.Thispaperattemptstoservethe purpose of being a one-stop academic and industrial ref-erence for scientific communities and professionals workingin this field. The paper further endeavors to serve as a meansto initiate the development of a next generation vibratoryfinishing system with real-time monitoring and surface finishmeasurements.Keywords Vibratoryfinishing.Shortcycletime.Eccentricweights.Mediamotion.Modeldevelopment.Fixturing1 IntroductionVibratory finishing has become increasingly significantover the last decades in the value chain of product de-velopment in a variety of industries especially aviation.This is due to enhanced automation of the process aswell as due to the many different process engineeringapplications of modern vibratory finishing technology.Yabuki et al. adequately summed up the versatility ofthe process in one line: it can be aggressive enough forremoval of burrs in steel parts as well as sufficientlydelicate to polish plastics 1.Vibratoryfinishingisaprocessunderthebroadumbrellaofmass finishing. Mass finishing consists of abrasive industrialprocesses by which a substantial quantity of componentsmadefrommetal orother materials can beeconomically proc-essed in bulk to achieve one or several of a variety of surfaceeffects such as deburring, edge radiusing, brightening,* S. H. Yeomshyeontu.edu.sg1Rolls-RoyceNTU Corporate Lab, c/o School of Mechanical &Aerospace Engineering, Nanyang Technological University, 50Nanyang Avenue, Singapore 639798, Singapore2School of Mechanical and Aerospace Engineering, NanyangTechnological University, 50 Nanyang Avenue, Singapore 639798,SingaporeInt J Adv Manuf TechnolDOI 10.1007/s00170-015-7942-0removing surface roughness, and stress relieving amongothers 2. With such a wide variety of applications, the pro-cesses are used extensively by the manufacturing industries.The inherent economy, flexibility, and adaptability of massfinishing systems have made them unique methods for im-provement of a vast variety of industrial parts. The conse-quences of not performing mass finishing processes can bequite severe: parts will perform poorly due to decreased loadcapacity, poor corrosion, and fatigue resistance to name a few.Thispapergivesanoverviewofthemassfinishingprocess-es,howmassfinishinghasevolvedovertheyears,andfocusesmainlyonthe machinesand machine characteristics thatbringabout the surface finish particularly for the vibratory finishingprocess. The key process variables for vibratory finishing, itsimportance in the aviation industry, and technological ad-vancements particularly to do with lowering the long cycletimes in such a process and the efforts that have been madeso far to understand this empirical process will also bediscussed briefly.2 Mass finishing and its historical developmentMass finishing is a general term for abrasive industrial pro-cesses, with loose particles known as media, together withcompound, all within a container in which components aresubmerged. Barrel finishing, vibratory finishing, centrifugalfinishing,anddragfinishingaresuchprocessesincludedwith-in broad purview of mass finishing. Energy is imparted to thisabrasive media by a variety of vibratory-cyclical motions tocause it to interact with part surfaces. To date, vibratoryfinishing is the most widely known mass finishing process.Mass finishing processes established their place in the in-dustry in the 1900s. Barrel finishing is said to be the originalmass finishing method. The first demonstration of massfinishing process was tumbling barrels with natural stonesused by ancient Chinese and Egyptians to polish theirweapons and jewelry 3. Mass finishing processes haveevolved in technology and innovation. This has resulted inmany variantsbarrel finishing, vibratory finishing, centrifu-gal finishing, and drag finishing. Although the key processvariables (KPVs) of any mass finishing setup vary from pro-cess to process, they can be classified under four broad head-ings as shown in Fig. 1. Since these four KPVsmedia, com-pound, machine, and workpieceare highly interdependent,theycanbevisualizedasatetrahedroncalledthe“Tetrahedronof Interdependence” 4.The functions of the various process parameters are as fol-lows 4, 5:1.Media: Media is the main element responsible forimparting the necessary surface finish to the components.It can be abrasive as well non-abrasive.2.Compound: Compound is the water-based lubricant andcoolant in the process. It has a lot of usesdrainingabraded material, cleaning the surface to be finished,and controlling the pH of the process among others.3.Machine type: Mass finishing machines have evolvedsince the inception of the process. From barrels to dragfinishers, there has been a continuous evolution of tech-nology and efficiency. Different machines differ in theirfinishing actions and the media motion inside themachine.4.Workpiece: Workpiece is the most important of the pro-cess variables. The workpiece dictates all of the aboveparameters.Forexample,thesizeandmaterialofthecom-ponents to be processed dictate the type of the machineand media. A large component undergoing polishing willhave to be finished in a big machine with a suitablepolishing or non-abrasive media and compound.The factors inherent to the mass finishing processmedia,compound, and machine type have witnessed many improve-ments since the industrial deployment of mass finishing. Themost significant have been in terms of the machine type. Thisevolution of technology is shown in Fig. 2.3 Vibratory finishing in the aviation industryDavidson 7 duly summarized why edge and surface condi-tioning is critical: “Sometimes, to fully understand the signif-icance of edge and surface quality issues, it is important tounderstandthe magnitudeoftheconsequenceswhenedgeandsurface condition receive insufficient attention.” The end-products of the aviation industry operate with human life ona daily basis and thus there are stringent requirements on edgeand surface conditions when it comes to the processes in-volved in the industry.The aerospace industry demands very fine surface finishrequirements for parts such as fan and turbine blades. If thefan blades have smooth surfaces, the risk of deposits stickingto the airfoil surface is reduced. The smoother the airfoil sur-faces, the lower the engine operating temperatures. This allowsa greater margin to be achieved between the actual exhaust gasMass finishing KPVs Workpiece Machine type Compound Media Outcome (finished components) Fig. 1 Mass finishing KPVsInt J Adv Manuf Technoltemperature and the engine “red line”maximum exhaust gastemperature (MEGT) as shown in Fig. 3. This temperaturereduction improves the time between overhaul for aircraft en-ginesthey can remain in service longer before an overhaul isneeded 8. Improved surface finishing of turbine blades alsoenhancestheaccelerationandcompressionoftheairmassflowinturbines,resultinginlowerfuelconsumptionaninvaluabletechnical benefit with rising costs of fuels nowadays 9. Low-ering surface roughness also helps in increasing fatigue life 7.This is important as the airplane components are subject tovarying amount of stresses during operation.The stress concentration in components like fan blades orturbinebladesinanaircraftengineisincreasedbysharpcornersas well as burrs. Deburring and edge radiusing reduces stressconcentration, which further increases fracture resistance andfatigue life. It has been observed that most fatigue cracks areinitiated at the surface of a part rather than internally. Hence,surface conditioning becomes critical for the long and safe lifeofapart,especiallyintheaerospaceindustry.Duringassembly,roughsurfacesandsharpexterioredgescanalsodamagecoatedor painted surfaces. Sharp outside corners on a structure act aselectrical charge accumulators and can be a static dischargehazard. During flight operation, sharp edges may have an im-balance of electric charges and can become spark over pointswhenever voltage is applied. This potential difference can becaused by static charge and/or lightning strikes 7.Vibrating barrels produce better surface finish High speed rotating disc produces faster finishing action Fixturing the workpiece improves process cycle times Spindle/drag finishingVibratory finishingBarrel finishingCentrifugal disk finishingFig. 2 Evolution of mass finishing technology 5, 6Int J Adv Manuf TechnolVibratory finishing is one such widely used process whichcan result in attaining the surface finish requirements specifiedby the aviation authorities as well as conditioning the parts tocounter the potential disasters caused by the phenomena de-scribedabove.Theprocessisflexibleandcosteffectiveintermsofnumerouspartswithcomplexgeometry(whichis usuallythecase with aerospace parts) can be finished simultaneously withminimal effort in process planning. Vibratory finishing helpsdevelop beneficial compressive stresses as well provide a stressequilibrium enhancement throughout the part, as all part fea-tures are processed identically. These compressive stresses willcounteract the tensile stress caused by a crack and help to con-tain its propagation. Many machining and grinding processestend to develop residual tensile stresses in the surface area ofparts. These residual tensile stresses make parts susceptible topremature fracture and failure when repeatedly stressed. Vibra-tory finishing counters this by imparting residual compressivestresses 7. However, vibratory finishing requires long cycletimes associated with such a process. The lack of science andunderstanding of the mechanism behind the vibratory finishingprocess is a barrier to optimizing the process to its full potential.In component applications, a typical fan blade in the aero-space industry has a length of 1,200 mm and a width of500 mm. A tub vibrator is used to finish these blades. Smallerand rotatory aerospace components such as turbine blades,blisks, and compressor discs are finished in a vibratory bowl.During the finishing process, fixtures are used to mount thesecomponents to prevent any damage from nicking or other im-pingements on delicate edges 10. The role of fixturing will beelaborated further in Sections 4.2 and 6.4. The airplanes struc-tural fuselage components and wing spars undergo deburringand radiusing in bigger tub vibrators. Parts that are deburredand have smooth radii in contrast to sharp edges have higherresistance to fatigue crack initiation and propagation. Paint ad-hesion on part edges is improved as well, which is useful fordownstream manufacturing processes 8, 10.4 Vibratory finishing KPVsVibratoryfinishingisacomplexprocesswhereeachandeveryoperating parameter plays a crucial role in bringing out thedesired surface finish. Vibratory finishing machines come intwo major configurationsthe bowl and the trough. Thesetwo configurations address the variations in the size and vol-ume of components to be finishedfrom huge componentslike fan blades to small components like turbine blades. TheKPVs are the same irrespective of the machine. Each keyprocess variable is interdependent and one cannot be ignoredover the rest in bringing about the required surface finish. Asmentioned in Section 1, the Tetrahedron of Interdependencewill always be intertwined for any mass finishing process toobtain the finished product.Dependingonthetypeofcomponent,itsdesiredoutput,andpotential application, the KPVs can be ranked sequentially.Though frequency of the vibratory motor is the most importantparameter while selection of media is the next as the frequencyofvibrationsfromthemotoraretransmittedtothemediawhichprovide the main finishing action to the component, other as-pects such as the right amount of dosing of the compound forlubrication and cleaning apart from other machine parametersare also vital. These parameters are listed in Fig. 4.The literature review on the key aspects of the machinecharacteristics is summarized in Fig. 5. The motor and theeccentric weights collectively are referred to as the unbal-anced mass drive system and is the core of the vibratoryfinishing process. Sections 4.1 and 4.2 will elaborate moreon the unbalanced drive system and fixturing.4.1 Motor and eccentric weightsAt the heart of the vibratory finishing process is a motor witheccentric weights, hence the name “unbalanced mass drivesystem”. It is attached to the bowl or the tub which is fixedto the ground by means of springs. Eccentric weights are at-tached to the ends of the motor shaft which causes wobblingaction when it rotates, which in turn vibrates the assembly.The frequency is usually controlled by specifying the speedof the motor. The amplitude and direction of rotation arechanged by modifying the eccentric weights attached to themotor. These are referred to as the input parameters of theprocess in addition to the type of compound and media. Typ-ical ranges for frequency and amplitude are 2060 Hz and 210 mm, respectively 5.High-speed motors are also being implemented to reducecycle times 11, 12. The speed of the motor designed in 11was up to 40 Hz as compared to between 20 to 25 Hz operatingin similar machines and the time taken to reach roughness sat-uration reduced by approximately 40 %. In both the references11,12,thereisaconsensusonthefasteranduniformrotationalmovement of the media in a high-speed vibratory finishingMEGTExhaust gas temperature Smooth airfoils Rougher airfoils Fig. 3 The effect of surface finish on aircraft engine exhaust gastemperaturesInt J Adv Manuf TechnolVibratory finishing processCompoundCompositionGrit sizeGrit materialEmulsifying agentMediaShapeSizeMaterialCoarseness of the gritCompositionWeightMachineFrequencyAmplitudeBasic designShapeCapacityWork pieceMaterialInitial roughnessSurface areaToughnessGeometryLocationSizeWeightLoadingAmount of mediaAmount of abrasivesAmount of waterVolume of partsWeight of partsFig. 4 Vibratory finishing KPVs3Machine characteristicsMotorPositionSpecification (frequency)Eccentric weightsPositionMass (amplitude)FixturesStatic/ dynamicShapeIntegrated/ separateVibratory vesselCapacityShapeBowlTroughOthersUnbalanced mass drive system Fig. 5 Vibratory finishingmachine characteristicsInt J Adv Manuf Technolmachine in comparison to a conventional one. However, therehave been contrasting observations made pertaining to mediasamplitude of vibrations. In the machine designed in reference11,theamplitudeofmediavibrationsreducesathigherspeedsand the media maintains a much more consistent contact timewith the component. These result in lower surface impinge-ments and a more homogeneous surface finish on the entiresurface of the components in a shorter cycle time. Rawlinson12attributesfastercycletimestouniformandincreasedmediaspeed and a precise control of high amplitude of vibrations.Further research can be conducted to ascertain which level ofamplitudelow or highis responsible for faster finishing athigh frequency of vibrations. Changes in eccentric weights toalter the amplitude will play a crucial role in understanding therole of high/low amplitudes in a high-frequency machine.For a vibratory bowl, the motion of the workload in themachine is considered as helical. There are two types of mo-tions“roll”motioninwhichmediarisesattheouterdiameterwall and falls down toward the center hub and the “feed”motion in which the workload travels clockwise or counter-clockwise lapping path around the bowl channel as illustratedin Fig. 6 by Domblesky et al. 13. Roll motion is determinedby the mass of the lower eccentric weight, whereas feed mo-tion is determined by the mass of the upper eccentric weight.By convention, the bottom eccentric weight always leads thetop weight in the direction of rotation of the drive shaft,whereas the media always rotates in the direction opposite tothe drive shaft rotation. The angle between the two eccentricweights, known as the lead angle, controls both roll and feedmotions 5. This concept is well illustrated by Nebiolo 14and is shown in Fig. 7.Foravibratorytrough,themethodofinducingvibrationsisthe same as in vibratory bowls. The motion is simplerit isrotatory as shown in a cross section of a trough in Fig. 8 3.4.2 Fixturesan upcoming trendThere has been limited research work in the literature withrespect to immobilization of the workpieces by deployingfixtures which offers another research approach. 15, 16.For high-value components such as turbine blades, it be-comes important to immobilize the workpieces to preventthem from colliding into one another. The other advantagesof fixturing include faster cycle times, finer surface finishes,and prevention of damage to the bowl liner from the sharpedges of parts 3.Fixturing of components is rather a relatively new conceptinthefieldofvibratoryfinishing,wherethecomponentisheldby suitable means and immersed into the media container.This type of fixtured vibratory finishing is also referred to asvibrostrengthening 16. These fixtures can be static (fixed onthe vibratory setup) or dynamic (freely floating). Both theconfigurations are known to speed up the finishing processproducing desired Ravalues in lesser cycle times. This is be-cause the force flow of media against the components is saidtoincreaseconsiderably and there isan increase in the relativevelocities between the media and the workpiece 1517.In a way, drag finishing, spindle finishing, and streamfinishing are advanced forms of fixtured finishing. In boththese methods, the parts that are to be finished are clampedby suitable means. These methods are known to reduce cycletimes by almost 33 % compared to conventional vibratoryfinishing 5.5 Patent analysisA thorough patent search related to vibratory finishing wasalso carried out in this work in order to determine the innova-tions that have come about pertaining to the various KPVs ofvibratory finishing. A general trend that was observed wasthat most of the patents dealt with improving the vibratoryfinishing process in terms of improving cycle times and pro-ducing quality surface finish.Going along the lines of high-speed vib