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Seminario Vibrazioni in Lavorazione


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Seminario Vibrazioni in Lavorazione

  1. 1. from research .… to market Integrated analysis of machine tools and cutting process Marco Leonesio marco.leonesio@itia.cnr.itMilan, 14th of February 2011
  2. 2. Contents• Machine tools specifications for heavy machining• Objectives of machine tools Virtual Prototyping• Integrated Modeling Approach: structure, control and cutting process• Ongoing research developments• Conclusions 2
  3. 3. Machine tools specifications for heavy machining Aluminium rib Titanium impellerIn some components for aerospace industry up to 90% of the material is removed fromthe workpiece during cutting, therefore Material Removal Rate (MRR) is typically animportant machine tool performance.On the other side, some machine tools are designed and built aiming at specificmachining operations (or even parts) that should be performed with an acceptablequality … Specifications in terms of machining Machine design operations 3
  4. 4. Machine tools specifications for heavy machiningTwo main needs arise from this situaution: To decrease the risk of requirements To avoid the costs due to mismatching (above all when the over-sizing prototype cost is unaffordable) Focus the design on specific cutting Increase analysis operations efforts to anticipate problems•Identification of an independentset of cutting operations relevantfor MT design; Virtual Prototyping•Synthesis of the static anddynamic behaviour sutited to therequired operations. 4
  5. 5. Objectives of machine tools Virtual Prototyping The adoption of rich numerical modeling of the designed product(a.k.a. Virtual Prototyping) allows the NPD to close a new and much faster loop, compared to the “testing stream”.In order to emulate physical validation tests, the models should be predictive… 5
  6. 6. Objectives of machine tools Virtual Prototypingstructure components process control 6
  7. 7. Integrated Modeling Approach Machine modeling for N.C. performance prediction drives measured displac. motor motors sensorstorques transmis- structure sions guideways workpiece spindle and tool quality tool cutting motion cutting process forces cutting param. 7
  8. 8. Integrated Modeling ApproachComponents libraries have been developed in Matlkab/Simulink environment enabling frequencydomain analysis and functional simulations of the whole machine during cutting. Tool Center Pos(1x1x 1 vector ) ChipThickness [mm] processo milling Vel mandrino 360 [rpm]1 RPM*2*pi/(60) Vel mandrino 360 [rpm] di taglio Force on tool (x,y ,z) D o Cut [mm] process Lavorazione LINEA (vel x = 18.24 mm/s) b D o Cut [mm] fresatura forze i74340.02WorkPX o74340.02WorkPX o74340.03WorkPY spost -K- i74340.03WorkPY o74340.01WorkPZ -4 o74341.02ToolX Spost azionamenti i74340.01WorkPZ o74341.03ToolY Rel axis drives MeccAzTandemUnitsV1FIG.mdl o74341.01ToolZ processo tandem i74341.02ToolX o74338.25VMotX1R o74338.26VMotX2L PosRef i74341.03ToolY Pos Com Motor1 Force [Xdata] o74338.05PMotX1R Vel Com GotoX1 AccLimRamp 1 Meas AX Pos Motor mass [kg] o74338.06PMotX2L OutX1 i74341.01ToolZ - Mot1 vel Motor2 Force Meas Mot1 Pos o74302.02LinEncX [Xdata] Mot2 vel Response1 F_Xdata i74338.05MotX1R o74339.24VMotY1R Meas Mot2 Pos Excitation input Response2 o74339.26VMotY2L Siemens Reg TandemCont X 1 [Ydata ] i74338.06MotX2L o74339.04PMotY1R Pos Com GotoY1 Motor1 Force Vel Com o74339.06PMotY2L OutY1 1 Meas AX Pos Motor mass [kg] i74339.04MotY1R o74302.03LinEncY Mot1 vel -1 Motor2 Force Meas Mot1 Pos o74337.24VMotZ1R [Ydata ] Mot2 vel Response1 i74339.06MotY2L F_Ydata Meas Mot2 Pos Excitation input Response2 i74337.04MotZ1R o74337 o74337 .25VMotZ2L .04PMotZ1R [Zdata] reduced struttura Siemens Reg TandemCont Y 1 GotoZ1 Pos Com Vel Com Motor1 Force o74337.05PMotZ2L OutZ1 FE FEM i74337.05MotZ2L o74302.01LinEncZ 1 -2 Meas AX Pos Mot1 vel Motor mass [kg] Motor2 Force model ridotto Meas Mot1 Pos [Zdata] M_VINCOLATO_TERRA _RMod Mot2 vel F_Zdata Response1 INPUTSN, Nm : Meas Mot2 Pos OUTPUTSmm, rad : Excitation input Response2 Siemens Reg TandemCont Z 1 8
  9. 9. Integrated Modeling Approach: structure & control Gear Belt transmissiontransmission spindle bearing Nut Vipromwiki,Drives business model 1 ELEMENTS NOV 22 2007 17:37:57 carriages 9
  10. 10. Integrated Modeling Approach: structure & control The virtual machine tool prototyping platform allows the designer to rapidly build a complex model but today a proper accuracy is not always assured: further research is needed. Cedevolezza dinamica al naso mandrino experimental Simulata Sperimentale -7 10 mod [m/N] -8 10 -9 10 numerical -10 10 machine+ spindle 1 2 10 hz 10 modes VELOCITA SU RIFERIMENTO DI COPPIA, ASSE X ANELLO APERTO experimental 50 NUMERICO VELOCITA SU RIFERIMENTO DI VELOCITA ANELLO CHIUSO, kvel=400 SPERIMENTALE FEM ACCELEROMETER ACCELEROMETRO 45 40 experimental 0 35 -5 30 NUMERICO SPERIMENTALE 25DB -10 DB 20 MARTELLOnumerical INSTRUMENTED STRUMENTATO HAMMER 15 -15 10 5 numerical SPINDLE FLANGIA TOOL NASO -20 FIXACTION MANDRINO ATTACHMENT MANDRINO 0 1 2 1 2 3 10 10 10 10 10 HZ HZFunction response frequency of a machine tool, dynamic behavior 10
  11. 11. Integrated Modeling Approach: cutting process Cutting process modeling and simulation (milling and turning) Force model: F=f(actual chip section). Different models implemented Variable Spindle Speed supported Run-outs effects Rountines for model parameters Lav01 (ATI Porcupine) - D=63mm - Z=4 - Ap=8mm - Ar=12.5mm - Sp=253rpm identifications (cutting coefficients, 1000 Fx fitting run-outs,…) [N] 0 -1000 650 700 750 800 850 900 950 1000 Displacement force 2000 Fy fitting 0 [N] -2000 -4000 650 700 750 800 850 900 950 1000 Samples Results: - predict chatter occurrence - estimate surface finish - predict realistic spindle torques and axes forces - test special chatter suppression techniques (Spindle Speed Variations) 11
  12. 12. Integrated Modeling Approach: cutting process Steel face-milling 8 teeth inserted endmill D=80mm Width of cut: 50mm Depth of cut: 5mmVirtual prototyping allows thedesigner to investigate the machinebehavior in operational conditions 12
  13. 13. Ongoing reseach developments Chatter is a complex phenomenon: even if it is an old problem, some scientific challenges are still open. DASM group does reasearch on the following topics, in co-operation with MUSP (a consortium of POLITECNICO of Milan): Spindle Speed Variation: In order to suppress chatter, one of the possible strategies is to continuously vary the spindle speed during the cutting process in order to break the regenerative process. Process damping: At low spindle speed, chatter stability limit is often increased by a phenomenon called process damping. A satisfactory predictive model of process damping is not available in literature. Experimental stability Lobes6 6 Bubble diameter is proportional5 5 to acceleration RMS 7 (in feed Depth of(mm) [mm] direction) measured on spindle Depth of Cut (mm) 6 housing. passata Cut4 4 5 43 3 3 22 2 1 01 1 0 500 1000 1500 2000 2500 600 600 800 800 1000 1000 1200 12001400 14001600 1600 1800 1800 2000 2000 Spindle Speed (RPM) velocità mandrino(RPM) velocità mandrino(RPM) Spindle Speed 13
  14. 14. Ongoing research developments: process dampingProcess damping mechanism •Tool Vibration •Surface Waviness *zoom (x100)Variables:Micro-Geometry ForceCoatings Output:Cutting speed ForceVibration Temperature Deformation Wear Ksp = F/V Compressed Volume FEM simulation are performed aiming at: •Support the prediction of lobes diagram modeling process damping •Tool Design 14
  15. 15. Ongoing research developments: grindingA model of grinding process is being developed, based on removalspecific energy, enabling chatter occurrence simulation. Chatter in grinding y, dy/dt x, dx/dt dFt dFn 15
  16. 16. ConclusionsVirtual prototyping of machine tools with cutting process can be the key totackle successfully the design of machine tools with high Material Removalcapabilities.Nevertheless, in order to make Virtual Prototyping efficient andeconomically feasible, new co-operation models have to be developedenhancing the synergies between machine tools manufacturers andcomponent suppliers, with the support of knowledge provider (Universitiesand research centres).As virtual prototypes must be predictive, a relevant amount of research hasto be still carried out in order to refine the estimation of chatter stabilitylimit and machine tool static and dynamic behaviour. 16
  17. 17. from research .… to marketThanks for the attention!