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Ghahremani Nik, Mohsen | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42992 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Akbari, Javad; Movahhedy, Mohammad Reza
  7. Abstract:
  8. In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding (UAG) is an efficient machining process for hard-to-cut materials with poor machinability. UAG improves the machinability of such materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are compared between CG and UAG processes. An ultrasonic setup is designed, optimized and fabricated based on combination of mathematical modeling, FEM analysis and genetic algorithm. Comparison between CG and UAG at several cutting and feed speeds and cutting depths are carried out, and the effect of ultrasonic vibration in dry condition is also studied. The results show 14% reduction in grinding forces and 10% improvement in surface roughness in average when ultrasonic vibration is introduced to the conventional process. The effects of variation at amplitude magnitude and changes at vibration direction are considered too. More declines in grinding forces are available by increasing vibration amplitude. The least grinding forces obtained when vibration was imposed at 45 degree related to feed direction where best surface roughness are available when vibration are at feed direction. Consequently due to reduction of grinding forces and surface roughness in UAG, grinding at higher cutting depth and cutting speed by lower coolant consumption are possible which lead to more production rate and lower manufacturing cost
  9. Keywords:
  10. Ultrasonic-Vibration ; Grinding ; Genetic Algorithm ; Titanium Alloy 6AL-4V ; Ultrasonic Assisted Grinding

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