Journal of the Korean Society for Precision Engineering (한국정밀공학회지)

Korean Society for Precision Engineering (한국정밀공학회)
권호 표지

Design and Testing of a Long Stroke Fast Tool Servo for Ultra-precision Free-form Machining

초정밀 자유곡면 가공용 long stroke fast tool servo의 설계 및 특성 평가

  • Kim, Ho-Sang (Center for robot and manufacturing tech., Institite for Adv. Eng.) ;
  • Lee, Kwang-Il (Center for robot and manufacturing tech., Institite for Adv. Eng.)
  • 김호상 (고등기술연구원 로봇/생산기술센터) ;
  • 이광일 (고등기술연구원 로봇/생산기술센터)
  • Published : 2009.02.25
Download PDF
⟨ Previous Next ⟩

Abstract

Long stroke Fast Tool Servo (LFTS) with maximum stroke of $432{\mu}m$ is designed, manufactured and tested for fabrication of optical free-form surfaces. The large amount of stroke in LFTS has been realized by utilizing the hinge and lever mechanisms which enable the displacement amplification ratio of 4.3. In this mechanism the peculiar shape was devised for maximizing the displacement of end tip in LFTS and special mechanical spring has been mounted to provide the sufficient preload to the piezoelectric actuator. Also, its longitudinal motion of tool tip can be measured by capacitive type displacement sensor and closed-loop controlled to overcome the nonlinear hysteresis. In order to verify the static and dynamic characteristics of designed LFTS, several features including step response, frequency response and cut-off frequency in closed-loop mode were experimentally examined. Also, basic machining result shows that the proposed LFTS is capable of generating the optical free-form surface as an additional axis in diamond turning machine.

Keywords

References

  1. Brecher, C., Lange, S., Merz, M., Niehaus, F., Wenzel, C. and Winterschladen, M., 'NURBS based ultraprecision free-form machining,' Annals of CIRP, Vol. 55, No. 1, pp. 547-550, 2006 https://doi.org/10.1016/S0007-8506(07)60479-X
  2. Garrard, K., Bruegge, T., Hoffman, J., Dow, T. and Sohn, A., "Design tools for freeform optics," Proceedings of the SPIE, Vol. 5874, pp. 95-105, 2005 https://doi.org/10.1117/12.617680
  3. Patterson, S. R. and Magrab, E. B., 'Design and testing of a fast tool servo for diamond turning,' Precision Engineering, Vol. 7, No. 3, pp. 123-128, 1985 https://doi.org/10.1016/0141-6359(85)90030-3
  4. Dow, T. A., Miller, M. H. and Falter, P. J., 'Application of a fast tool servo for diamond turning of non-rotationally symmetric surfaces,' Precision Engineering, Vol. 13, No. 4, pp. 243-250, 1991 https://doi.org/10.1016/0141-6359(91)90001-Y
  5. Kim, H. S., Kim, E. J. and Song, B. S., "Diamond Turning of Large Off-axis Aspheric Mirrors using Fast Tool Servos with On-Machine Measurement," Journal of Materials Processing Technology, Vol. 146, Issue 3, pp. 349-355, 2004 https://doi.org/10.1016/j.jmatprotec.2003.11.028
  6. Kim, H. S. and Kim, E. J., 'Feed-forward control of fast tool servo for real-time correction of spindle error in diamond turning of flat surfaces,' International Journal of Machine Tools and Manufacture, Vol. 43, Issue 12, pp. 1177-1183, 2003 https://doi.org/10.1016/S0890-6955(03)00156-1
  7. Kim, H. S., Kim, S. I., Lee, K. I., Lee, K. M. and Bang, Y. B., 'Development of long stroke fast tool servo for diamond turning machine with its range of 432$\mu$m,' Proc. of KSPE Spring conference, pp. 497- 498, 2008
  8. Paros, J. M. and Weisbord, L., 'How to Design Flexure Hinges,' Machine Design, No. T-27, pp. 151-156, 1965
  9. Musa, J. and Renyi, Y., 'Modeling of flexure-hinge type lever mechanisms,' Precision Engineering, Vol. 27, No. 4, pp. 407-418, 2003 https://doi.org/10.1016/S0141-6359(03)00045-X
  10. Kinetic Ceramics Inc., Products Catalogue, pp. 16-19, 2008
  11. O'Neill, C. G., 'Piezoelectric positioner,' US Patent, No. 6040653, 2000
  12. Musa, J. and Renyi, Y., 'Modeling of flexure-hinge type lever mechanisms,' Precision Engineering, Vol. 27, No. 4, pp. 407-418, 2003 https://doi.org/10.1016/S0141-6359(03)00045-X