Working fluid Pressure sensor Rotation Grinding wheel Initial gap Wear Workpiece Principle of measurement by using hydrodynamic pressure 圧力センサ Pressure sensors DCモータ motor タコジェネレータ Tachometer カップリング Coupling 軸 Shaft 円盤 Disk 渦電流式変位センサ Eddy current sensor Experimental apparatus Gap 50 m m/div Hydrodynamic pressure 50 kPa/div Pressure Gap 0 20 40 60 80 Time ms 10 10 3rd cut 15 3rd cut 2nd cut 10 2nd cut 30 20 WA#800 10 1st cut 5 0 0 50 100 150 200 Initial 250 0 Minmum gap mm 10 0 101 10-2 Gap 1 0 Initial 0 Pressure 10-4 WA#46 1st cut 5 x=+1.5 mm Peripheral speed 28.7 m/s Pressure kPa Pressure kPa 15 Pressure kPa D#400 20 0 50 100 150 200 250 Gap mm 103 2 40 60 80 Minimum gap mm 100 10-1 10 100 1000 Frequency Hz Examples of outputs of sensors Influence of grain size Trajectory of pressure to gap 60 1.5 1st cut 6 2nd cut 3rd cut 40 0.5 Measured pressure 0 100 110 120 Gap mm 130 Average pressure vs. gap 140 1 20 0 5 Pmax-Pmin 20 40 60 Pmax-Pmin kPa Pressure kPa Pressure kPa 7 Initial 0 80 Gap m m 40 100 Minimum gap mm Dispersion of measured pressure (C)2001 Manufacturing Engineering Laboratory, Detection of loading of grinding wheel 12-1, Hisakata 2-chome, Tempaku-ku, Nagoya 468-8511 JAPAN Background and problem • Monitoring of grinding wheel wear for precision grinding • Disturbance of light by working fluid Solution • Gap sensing by using hydrodynamic pressure with pressure sensor arranged with small gap Advantages • Simple sensing device • In-process measurement of radius and topography of grinding wheel • Dependence of only geometry of grinding wheel Results • Relationship among pressure, gap and speed • Enable to run-out by arranging several sensors • Standard deviation of 1 mm in measured radii • Enable to detect loading, shedding and dulling Applicable field • Plunge grinding • Creep-feed grinding • High precision grinding such as ELID • Grinding expensive material • Small-amount products Pressure kPa URL: http://www.toyota-ti.ac.jp/Lab/Kikai/5k60/ In-process Measurement of Wear of Grinding Wheel by Using Hydrodynamic Pressure Three-dimensional Form Generation by Dot-matrix Electrical Discharge Machining Main axis of Quill of electrical electrical discharge discharge machine machine Electrode feeding device 12-1, Hisakata 2-chome, Tempaku-ku, Nagoya 468-8511 JAPAN Wire electrode Solution • Shaping profile of bundled electrodes by controlling their length and scanning them as one electrode Advantages • Enable to skip making process of electrode • Mechanical strength of electrode • Enable to compensate electrodes for heavy wear by feeding them • Use of thin wire for electrodes Results • Machining 3D shape with 6 thin electrodes • Less cracks by divided power because of discharge dispersion Applicable fields • Micromachining • Micromold fabrication • Rapid prototyping for metals Machining unit Electrode guide Workpiece NC table Concept of dot-matrix electrical discharge machining Appearance of machining unit System configuration -0.5mm 0 Positioning sequence of electrodes 0 5.1mm Designed shape Machining sequence -0.5mm -250 -300 0 2000 4000 x mm 6000 -300 0 2000 4000 x mm Improvement of waviness 6000 0- 5.1mm Result of machining Example of machining (C)2001 Manufacturing Engineering Laboratory, EL2 EL3 EL4 EL5 EL6 0.5 A Depth mm -250 EL1 EL1 Discharge current -200 0 0.5 A -200 Divided power Types of power supply for dot-matrix EDM Discharge current -150 Equi-potential power 0 -150 Depth m m URL: http://www.toyota-ti.ac.jp/Lab/Kikai/5k60/ Background and problem • Needs for rapid production system for metals • Difficulty in production of tool electrode to machine small shape EL2 EL3 EL4 EL5 EL6 0 10 20 30 0 10 20 Time ms Time ms Equii-potential power Divided power Discharge dispersion 30 Precision Positioning Table Employing Parallel Mechanism for Scanning Probe Microscope Background and Problem • Cutting machine for nanometer depth of cut • unavoidable tilt of tube type piezoelectric actuator in general scanning probe microscope (SPM) Table Z Y X Electrode for detection Lever mechanism Stacked piezo with flexure hinges Eddy current displacement sensors Appearance of device Advantages • 6 degrees of freedom • High resolution in z because of small elevation angle • Flexible tool path • Enable to use in vacuum because of no slipping element Eddy current sensor 6° Flexure joints Base plate Electrodes for detection Stacked piezo 160 Lever machanism with flexure hinges Sectional view Semiconductor laser (5mW,635nm) Quadrant photo detector 75 Results • Smaller tilt (1/10 to tube type) • High positioning accuracy (16 nm in z) • Linearity within 20×20 mm by semi-closed loop control Table Specimen Cantilever Probe 0 Applicable fields • Ductile mode cutting of brittle materials • Micromachininig • Fine motion stage for SPM Table Parallel link Link Base platform Vibration isolating table Inverse kinematics R1 LPF Piezo L1 Sensor R2 Link length for given posture, Ri KP LPF KP Piezo L2 Sensor R6 LPF KP Piezo L6 Sensor 0.2 ③ 0.1 ⑦ -1.0 Output of P.D. V ⑤ ⑥ -0.5 0.0 Displacement of table mm (a) Open loop control 0.2 0.5 ③ 0.1 ① ② ④ 0.0 ⑦ -0.1 Block diagram of control system Cross talk ratio % Pitching error Feedback x/y z/y mrad None 19.6 8.2 12 Displacement 11.7 3.9 17 Induced charge 3.5 4.7 17 ④ 0.0 -1.0 Cross-talk ratio ② ① -0.1 Output of P.D. V Given posture of table Specifications Size: 16016085 mm Mass of table: 24 g Movable range: 100 mm in xy, 20 mm in z Resonance frequency: 100 Hz in xy, 75 Hz in z Degrees of freedom: 6 Actuators: Piezoelectric actuators Magnification: 12.5 Output of P.D. V Setup for atomic force microscope ⑤ ⑥ -0.5 0.0 0.5 Displacement of table mm (b) Displacement feedback control 0.2 ③ 0.1 ② ① 0.0 ⑦ -0.1 ④ ⑥ ⑤ -1.0 -0.5 0.0 0.5 Displacement of table mm (c) Induced charge feedback control AFM image of diffraction gratings (C)2001 Manufacturing Engineering Laboratory, Force curve on Silicon 12-1, Hisakata 2-chome, Tempaku-ku, Nagoya 468-8511 JAPAN Flexure joints 11 URL: http://www.toyota-ti.ac.jp/Lab/Kikai/5k60/ Solution • Stewart platform type parallel mechanism controlled by induced charge feedback method Base plate
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