Annoni, M.

Parenti, P.

Park, C. I.

Park, S. S.

PARENTI, PAOLO

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Increasing Stability of Meso/Micro Milling Cutting by means of Ultrasonic Vibration Assisted MachiningPaolo Parenti*, Chaneel I. Park**, Simon S. Park**, Massimiliano Annoni**Dept. of Mechanical Engineering, Politecnico di Milano**Dept. of Mechanical and Manufacturing Engineering, University of CalgaryCorresponding Authors:VMPT 2014Prof. Simon Park  simon.park@ucalgary.ca  http://www.ucalgary.ca/medal/Tel: 403 220 6959Prof. Massimiliano Annonimassimiliano.annoni@polimi.it  http://www.mecc.polimi.it/Tel: (+39) 02 2399 8536Micro Engineering Dynamics Automation Lab (MEDAL)Milling Process instability (Regenerative Chatter)• Poor Surface finish• Reduced Productivity• Excessive Tool Wear• Tool BreakageReceptanceCoupling (RC)Ultrasonic Vibration Assisted Machining• Chip Removal (cutting kinematics and cutting action)• Cutting force reduction (friction)• Machinable Materials (hard/brittle)• Burr formation• Toll Wear (including thermal and chemical)Experimental SetupKern CNC machining center Spindle: 60000 / 150,000 rpmResolution 0.1 μm Positioning tolerance ±1.0 μmController HeidenhainEnd mill 2 Flutes Diameter=500µmEdge radius≈2µmHelix=30° / Clearance=10°Young’s Module≈690GpaDynamic CharachterizationSingle Cristal Piezo Cylinder RF AmplifierSignal GeneratorProcess Improvement• Cutting Coefficients reduction (rake angle)• Tool dynamic modification (clamping)• Increased Process dampingEffects on Cutting StabilityR. Rahnama et al. / JMPT  209 (2009) 5766–5776M.Goletti (2009)Single-Axis Vibration at Ultra-High Frequency (100KHz-3MHz)1st tool mode• Reduction of cutting forces are measured through dynamometer during stable cuttingEMAFEM3-Axial Vibration at 20KHzSetup #20.5 1 1.5 2 2.5 3x 106-0.15-0.1-0.0500.050.10.150.20.250.3Points / timeForce X [N]Time history  0       5          10         15         20         25        30         35        40         45        50         55        60 [s]Force X [N]Monitoring signals(chatter detection)• Acoustic Emission• Accelerometers• Forces (up to 5KHz)Piezo-Electric ActuatorsLobes Diagram Calculation and VerificationtooltoolWPWP• Stability Lobes diagram is verified with and without application of UVAM techniqueCutting testsGOALS:• To verify experimentally the force reduction by applying UVAM in different directions with very high vibration frequency• To investigate the increased cutting stability with respect to the regenerative chatter phenomenon• Chatter detection is based on AE sensor/ Accelerometer • Effects of high assisting frequency (>100KHz) are investigated and compared with lower frequency (20KHz)• Process cutting modelling through Mechanistic and FEM approach are foreseen • Industrial exploitability of the solution is also addressedto avoid

Increasing Stability of Meso/Micro Milling Cutting by means of Ultrasonic Vibration Assisted Machining

https://re.public.polimi.it/retrieve/handle/11311/978225/64060/Increasing%20stability%20of%20mesomicro%20milling%20cutting%20by%20means%20of%20ultrasonic%20vibration%20assisted%20machining.pdf

Increasing Stability of Meso/Micro Milling Cutting by means of Ultrasonic Vibration Assisted Machining

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