Subbiah, Sathyan

Scholarly Materials And Research @ Georgia Tech

PMRC IAB Meeting, October 29, 2002TURNING HARDENED STEEL USING ROTARY CUTTING TOOLSSathyan Subbiah, Graduate Research AssistantShreyes N. Melkote, Ph.D., Assoc. ProfessorPMRC IAB Meeting, October 29, 2002ObjectiveDevelop a robust process by optimally combining suitable grades of PCBN with rotary cutting action, for continuous and interrupted cuttingPMRC IAB Meeting, October 29, 2002Introduction• Hard turning replacing grinding• Need for longer tool life - economics• Better tool material is one way – KB9640, BNX250, binderless CBN• Spreading wear over the entire edge is another – rotary cutting tool• Round insert rotates about its axis supported by bearing – spreads wear• Optimal combination of the two PMRC IAB Meeting, October 29, 2002Rotary Cutting Action• Insert rotates about its own axis as it cuts• Can be driven externally, or,• Self propelled by chip – requires obliquityMovie source: www.lambtech.comSketch source: Journal paper by H. A. KishawySketch source: Journal paper by Chen Wuyi et al.PMRC IAB Meeting, October 29, 2002Proposed Tasks:1. Identify, acquire-modify/design-build a spindle assembly for rotary cutting tool2. Testing to select best cutting tool grade and edge geometry3. Process modeling4. Model validation5. Tool life testing and optimization6. Surface integrity characterization7. Case studyPMRC IAB Meeting, October 29, 2002Progress to date• Literature search• Identified new grades of PCBN for testing• Commercial rotary cutting tool• New tool design in progressPMRC IAB Meeting, October 29, 2002Literature highlights• Rotary action used as early as 1868• First reported modeling work in 1952 by M. C. Shaw• Several investigators have tried on difficult-to-machine materials (Titanium alloy, Inconel alloy, Al/SiP composites, hardened steel, Iron)• On interrupted cutting (e.g. alternator rotor)• Reported successes• Two patents exist for tool designPMRC IAB Meeting, October 29, 2002Literature highlights• Modeled as equivalent oblique cutting with the rotating action inducing an inclination of the chip• Recent work done in thermal modeling – not experimentally verified• No reported work in modeling dynamics• No reported work in modeling tool wear• No reported work in surface characterizationPMRC IAB Meeting, October 29, 2002Literature highlights• Reported lower temperatures and tool wear compared to conventional cutting with WC, Carbides, PCBN• Hardened steel: – Saw toothed chips not observed– Rotary speed of tool is linearly proportional to cutting velocity; more steeper at higher rake angles– Flank wear more dominant than crater wear• Surface waviness reportedPMRC IAB Meeting, October 29, 2002PCBN grades for testing• New grade from Kennametal – KB9640• Sumitomo grade BNX250• Sumitomo’s binderless CBN – not available commerciallyPMRC IAB Meeting, October 29, 2002Commercial Rotary Tools• Rotary Technologies Corporation• Milling tools available as standard products• Lathe tools made if requested• Special insert geometry (annular ring – 1inch OD, 0.5 inch ID)• Fixed inclination anglePMRC IAB Meeting, October 29, 2002Need for design changes• Incorporate standard round inserts • Need for flexibility to change inclination angles for experimentation purposesPMRC IAB Meeting, October 29, 2002New tool designMax gap available to place bearing beforetool holder hits workpieceMax gap available to place bearingTool holderWorkpieceInclination needed to provide selfpropelled motionInclination needed to provide space for bearinghθφ DThe amount of gap available depends on h, D (workpiececurvature), and θ(angle of rotation of tool holder)Rotating insertBearingWorkpiece Rotation Note: Tool feeds into thepaperPackaging IssuesPMRC IAB Meeting, October 29, 2002New tool design - conceptStandard Insert¾”1”PMRC IAB Meeting, October 29, 2002New tool designPMRC IAB Meeting, October 29, 2002Next …• Tool stress due to edge chamfer• Analyze tool design • Preliminary cutting with commercial tool to get feel for process• Experiments to choose grade

Turning Hardened Steel Using Rotary Cutting Tools

https://smartech.gatech.edu/bitstream/1853/13476/1/Sathyan_IAB.pdf

Turning Hardened Steel Using Rotary Cutting Tools

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