In-process Measurement of Wear of Grinding Wheel by Using Hydrodynamic Pressure

1
In-process Measurement of Wear of Grinding
Wheelby Using Hydrodynamic Pressure

• 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

Principle of measurement by using hydrodynamic
pressure
Experimental apparatus
Examples of outputs of sensors
Influence of grain size
Trajectory of pressure to gap
Detection of loading of grinding wheel
Dispersion of measured pressure
Average pressure vs. gap
2
Three-dimensional Form Generationby Dot-matrix
Electrical Discharge Machining

• Background and problem
• Needs for rapid production system for metals
• Difficulty in production of tool electrode to
  machine small shape
• 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

Quill of electrical discharge machine
Concept of dot-matrix electrical discharge
machining
Appearance of machining unit
System configuration
Positioning sequence of electrodes
Designed shape
Machining sequence
Types of power supply for dot-matrix EDM
Result of machining
Example of machining
Improvement of waviness
Discharge dispersion
3
Precision Positioning Table Employing Parallel
Mechanismfor 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)
• Solution
• Stewart platform type parallel mechanism
  controlled by induced charge feedback method
• 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
• Results
• Smaller tilt (1/10 to tube type)
• High positioning accuracy (16 nm in z)
• Linearity within 2020 mm by semi-closed loop
  control
• Applicable fields
• Ductile mode cutting of brittle materials
• Micromachininig
• Fine motion stage for SPM

Appearance of device
Sectional view
Setup for atomic force microscope
Specifications Size 160?160?85 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
Block diagram of control system
Cross-talk ratio
AFM image of diffraction gratings
Force curve on Silicon