Robot RV reducer virtual prototype simulation and analysis工程技术论文完整版下载.doc

中国科技论文在线robot rv reducer virtual prototype simulation and analysis1guan tianmin, zhang yinghui, he weidongdepartment of mechanical engineering, dalian jiaotong university, dalian, liaoning (116028) abstractbased on multi-body dynamics theory, paper established the virtual prototype of robert rv reducer.in the model building process, based on the working principle of rv reducer, define the meshingrelationship between the three planetary gears and the driving wheel as high-vice contact, define thethree planetary gears stably solid with the three crankshafts, which formed three parallel double-crankmechanism, define the meshing relationship between the cycloid gear teeth and needles also ashigh-vice contact, define the kinematic pair between the others components as revolve pair. afterformulating the virtual prototype, solved the dynamical equation by newmark method. simulationresults show that rv reducer drive smoothly, has stable dynamic performance, and ideally forprecision transmission.keywords: rv reducer; virtual prototype; dynamic simulation1 introductionrv transmission has many advantages, such as large transmission ratio, small size, high carryingcapacity and high transmission efficiency, which attracted widespread attention at home and abroad andused wildly at industries field. as shown in figure 1, the rv reducer is complex and difficult forstructure design and for kinematics, dynamics analysis. reference 1 mainly introduced the virtualassembly and dynamics characteristics research for planetary reducer; focus on the molding process,solving methods and result analysis. reference 2 focus on dynamics simulation of planetary cycloidreducer body, established a virtual prototype model for ordinary cycloid reducer with ug and adamssoftware, got the kinematics, dynamics simulation results, solved the force and constraint issues of keycomponents. reference 3 applied inertia plate to simulate working load, established the dynamicalmodel for rv-6a ii with 5 dof, then by the dynamic characteristic test to verify the correctness of themodel. reference 5 established a 24 dof dynamical model for rv reducer, obtained two keymeshing stiffness of rv, formulated the dynamical equation, and got the nature characteristic for wholemachine. being the complexity, few papers introduced the dynamical simulation of rv reducer. basedon the working principle of rv reducer, on the view of virtual design, paper establishes the virtualprototype model and conducted a simulation and analysis of kinematics and dynamics.2 working principle of rv reduceras shown in figure 1, rv reducer composed by two degree deceleration, first is the involute cylindricalgear, and second is cycloid reducer. the input gear shaft 1, assume the shaft 1 turns clockwise, gear1 will drive the three planetary gears 2, which layout at 120 degrees on the circle, revolution around thecentral axis and counter-clockwise rotating at the same time. three crankshafts 3 solid connected withthree planetary gears 2 and rotating with same speed, two layout 180-degree phase cycloid gears 4articulated with three crankshafts. the two cycloid gears meshing with the fixed pin wheel 5, being theaction of meshing force, it will revolution around the central axis of pin wheel and rotating clockwisein opposite direction at same time. the output mechanism, planet carrier 6 pushed by three supportsbearing on three crankshafts, which transferred the revolution of cycloid gears by ratio 1:1.1supported by research fund for the doctoral program of higher education of china (20060150001), programfor liaoning excellent talents in university (2006r08), transcentury training programme foundation for thetalents by the state education commission (ncet-07-0127)-1-中国科技论文在线5643271figure 1: working principle of rv reducer1. sun gear2. planet wheel 3.crankshaft 4. cycloid wheel 5.needle wheel6. planet carrier7. pin wheel housing3 virtual prototypes molding of rv reducer3.1 geometric modelingin the process of building the three-dimensional model, only include the key parts and character forthe simulation; simplify the components which doesnt affect the simulation results, such as bearingand keys.3.2 assumptions in the model buildingit is can be known from the working principle of rv reducer, the meshing between the pin wheel andcycloid gears are multi mesh. in real working, the loading between the pin wheel and cycloid gears,three crankshaft and planet carrier very complex; it will affected by contact deformation,manufacturing error, mesh gap and the deformation of cycloid gear. for research convenience, makethe following assumptions:(1)ignore the manufacturing error; (2)all components are regarded as rigid body;(3)dont consider the deformation of cycloid gear, pin wheel and crankshaft.3.3 constraints definition in the system(1) input gear shaft 1, only has rotation around the central axis; define it as rotary vice;(2) the kinematic relation between the three planetary gears 2 and the gear haft 1 are involute gearmeshing, which can be defined as gear pair or high pair, there it defined as high pair, that is surface tosurface.(3)the three crankshaft 3 connected with three planetary gears 2, has no relative motion, define them asa single part, that is regarded the planetary gear and the crankshaft as fixed.(4)the two cycloid gears 4 supported by crank bearing, which connected on crankshaft 3, for researchconvenience, omitted bearings, define relation between them are rotary vice.(5) the two planetary carriers 6 are output parts (for research convenience, only keep the right),rotating around the central axis, define it as rotary vice.(6) define needle-tooth shell and needle teeth as fixed connection, in real meshing, being the meshingforce , needle teeth has irregular rotation, for research convenience, omit it, and regard the whole partconnected with ground.3.4 mechanical model of the system(1) the driving force of three planetary gears come from the meshing of sun gear 1; define it as highpair, which is surface to surface.-2-中国科技论文在线(2) the driving force of two cycloid gears 4 come from the three planetary gears, the power ofrevolution from the meshing force which was the reaction between the cycloid gear and the pin wheels;also define the meshing as high pair.(3) the revolution of the two cycloid gears driven the planet carrier as output, define a load torque onthe planet carrier.4 dynamic simulations and analysis of virtual prototypingcalculation example, the key parameters of rv250aii reducer as follows: input speed 1500r/min,output torque 2450n.m, number of sun gear teeth is 21, planetary gears teeth number is 42, contactstiffness 5 of involute gear is k=2.32108n/m, number of needle tooth is 40, cycloid gear toothnumber 39, mesh stiffness 5 between the needle and cycloid wheel is 2.17105n.m/rad.4.1 motion analysisfigure 2 shows the centroid displacement curve of crankshaft on both x and y direction, crankshaft notonly rotating by it owns center axis, but also revolution by axis of planet carrier. both of thedisplacement follows the sinusoid curve.figure 2 displacement curve of crankshaft on x and y directionfigure 3 shows the centroid velocity curve of crankshaft on both x, y and z direction, on direction xand y, both velocity follows sinusoid curve with a phase. on direction z, there has obvious vibration,but the amplitude doesnt important.figure 3 velocity curve of crankshafton x, y and z directionfigure 4 shows the centroid acceleration curve of crankshaft on both x and y direction, it can be seenthat both at x and y direction there are obvious vibration during the meshing process.figure 4 acceleration curve of crankshaft on x and y direction-3-中国科技论文在线figure 5 shows the displacement curve of cycloid gear, cycloid wheel rotation does not producedisplacement, revolution around the central axis generated displacement, the displacement also a sinecurve. the amplitude is double of the length of crankshaft eccentric.figure 5 displacement curve of cycloid gearfigure 6 is the speed curve of planet carrier; curve shows the turning speed of planet carrier is smooth.figure 6 speed curve of planet carrier4.2 stress analysis of key componentsfigure 7 is the gear shafts force curve at centroid, curve shows that the gear shaft has larger impact atthe beginning, but become smooth very quickly.figure 7 gear shafts force curve at centroidfigure 8 shows the crankshaft synthetic force curve at centroid position, it can be seen that thecrankshaft bears a uniform loading with higher shock. in real loaded working, the force amplitude hasgreat effect on the life of crank bearing. so analysis of the force changing not only has help to bearingselection, but also can used for bearing life estimating, increase bearings service life.figure 8 synthetic force curve of crankshaft at centroidfigure 9 is the force varying curve of cycloid wheel.-4-中国科技论文在线figure 9 force varying curve of cycloid wheelfigure 10 shows the force curve of single pin wheel.figure 10 the force curve of single pin wheelfigure 11 is the load and power spectrum of three selected pin wheel, from the up curve on figure 11,all the force and phase are similar, which shows the machine has good performance of average loadbearing capacity and better stability. from the power spectrum it can be known that the vibrationenergy mainly distributed at 1 hz and 300hz, in it 1 hz representing the working condition whenmachine starting.figure 11 the load and power spectrum of three selected pin wheel5 conclusion(1) by appropriate simplification for rv reducer, omitting some parts which does not affect themovement effect, define the meshing between the involute planetary gears and the sun gear, the cycloidgear and the pin wheels both as high pair, solid connect the three planet gears and the three crankshafts,define the relation between the three crank shafts and two cycloid gears as revolving joint. establishedthe multi-body dynamics virtual prototyping for rv reducer, use newmark methods to solve thedynamical equation, which can obtain better simulation results with small steps.(2)through the simulation and analysis of displacements, velocity, acceleration and force for the keyparts of rv reducer, got the motion, force and vibration rule of crankshaft, cycloid wheel and needletooth. simulation results verified that rv reducer drive smoothly, has good load bearing and canworking stably; results can also has help for deep research and for rv reduce amelioration.acknow