A Machine Tool Spindle Achieving Real-Time Balancing Using Magnetic Fluid
Keiichi Nakamoto*, Shinya Mitsuhashi**, Kazuhiko Adachi**, and Keiichi Shirase**
*Department of Mechanical Engineering, Osaka University
2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
**Department of Mechanical Engineering, Kobe University
1-1 Rokko-dai, Nada, Kobe 657-8501, Japan
A machine tool spindle is a key component affecting the performance of machine tools. Spindle vibration of machine tools causes tool wear prematurely and decreases machining accuracy. The vibration changes depending on the used tooling and the rotation speed during various machining operations. In particular, even small unbalance mass of the spindle makes large whirl in high speed machining. However, real-time balancing of a machine tool spindle has not yet been realized successfully including the influence of the used tooling. In this study, in order to reduce unbalance response of a machine tool spindle and to achieve high accuracy machining, a real-time balancing mechanism using magnetic fluid is proposed. The magnetic fluid is enclosed inside the spindle, and the distribution of circumferential mass is controlled to compensate for unbalance mass in real-time. A test spindle is designed and developed in order to evaluate the real-time balancing mechanism experimentally. It is confirmed that unbalance response of the spindle is significantly improved. Based on the obtained results, a machine tool spindle achieving real-time balancing is developed in this paper. The experimental results proved the feasibility of the proposed real-time balancing mechanism for a machine tool spindle.
-  Y. Altintas and Y. Cao, "Virtual Design and Optimization of Machine Tool Spindles,'' Annals of the CIRP, Vol.54, No.1, pp. 379-382, 2005.
-  C. Brecher, G. Spachtholz, and F. Paepenmüller, "Developments for High Performance Machine Tool Spindles,'' Annals of the CIRP, Vol.56, No.1, pp. 395-399, 2007.
-  F. F. Ehrich, "Handbook of Rotordynamics,'' Krieger Publishing Co., pp. 3.1-3.117, 2004.
-  ISO 1940-1, Mechanical Vibration -- Balance Quality Requirements for Rotors in a Constant (rigid) State -- Part 1: Specification and Verification of Balance Tolerances, 2003.
-  ISO 11342, Mechanical Vibration -- Methods and Criteria for the Mechanical Balancing of Flexible Rotors, 1998.
-  K. Nakamoto, K. Adachi, and K. Shirase, "Proposal of Real-Time Balancing Mechanism Using Magnetic Fluid for Machine Tool Spindle,'' in M. Mitsuichi, K. Ueda, F. Kimura (Eds.), Manufacturing Systems and Technologies for the New Frontier, Springer, pp. 387-390, 2008.
-  H. A. Slocum, R. E. Marsh, and H. D. Smith, "A New Damper Design for Machine Tool Structures: the Replicated Internal Viscous Damper,'' Precision Engineering, Vol.16, No.3, pp. 174-183, 1994.
-  T. Aoyama and I. Inasaki, "Application of Electrorheological Fluid Dampers to Machine Tool Elements,'' Annals of the CIRP, Vol.46, No.1, pp. 309-312, 1997.
-  A. Milecki, "Investigation and control of magneto-rheological fluid dampers,'' International Journal of Machine Tools and Manufacture, Vol.41, No.3, pp. 379-391, 2001.