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Improving the Cylindrical Grinding of Engineering Ceramics by Applying Ultrasonic Vibrations and Laser Dressing

Zahedi, Ali | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48208 (08)
  4. University: Sharif University of Sharif
  5. Department: Mechanical Engineering
  6. Advisor(s): Akbari, Javad
  7. Abstract:
  8. Ultrasonic assisted grinding is a novel method for improving the grinding process of difficult-to-cut materials. In the present research a novel set-up has been designed and manufactured for utilizing ultrasonic vibrations in cylindrical grinding. The designed ultrasonic head vibrates a rotating workpiece in axial direction. An alumina-zirconia ceramic (AZ90) has been selected as the workpiece material. Energy aspects and workpiece surface characteristics of ultrasonic assisted cylindrical grinding (UACG) and conventional cylindrical grinding (CG) processes have been analytically modeled and corresponding grinding experiments have been performed. The combined kinematics of the cylindrical plunge grinding process and axial ultrasonic vibrations provide a unique surface treatment conditions, which leads to reduced peak heights and increased valley depths of the surface topography. The main axial vibration mode provides the overlap of the adjacent cutting traces and consequently smoothens the surface topography in cylindrical plunge grinding. It has been analytically and experimentally shown that, applying ultrasonic vibrations, grinding energy can be reduced up to more than 35% depending on the process parameters. The surface characteristics of the ground workpieces have been investigated in terms of four surface roughness parameters and the roundness error. As the extended application of diamond grinding wheels is limited owing to the challenges associated with their conditioning processes, it has been always searched for novel methods to replace the conventional approaches. Laser ablation is a novel non-mechanical wheel preparation method for optimizing the treatment costs of superabrasive tools. In this study, following a previously performed thermal analysis, proper laser treatment parameters have been suggested for conditioning of resin bonded diamond grinding wheels. The significance of the laser conditioning is the selective treatment of grinding wheel components. Accordingly, resin bonded and metal bonded diamond grinding wheels have been dressed with a picosecond Yb:YAG laser device. The performance of the laser dressed diamond wheels has been investigated in cylindrical plunge grinding of an alumina (AK99.5) and an alumina-zirconia (AZ90) ceramic as two industrial ceramics. The grinding power, average surface roughness, wheel wear and the mean roughness depth of the ground workpieces normal to the cutting direction have been measures as determining aspects of grinding efficiency
  9. Keywords:
  10. Engineering Ceramics ; Ultrasonic Assisted Grinding ; Surface Grinding ; Surface Roughness ; Yag Lasers ; Ultrasonic-Vibration ; Remaining Useful Life ; Diamond Grinding Wheel

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