Abstract
This paper deals with the design of dynamic damper utilizing magnetic fluid and the vibrational damping characteristics of boring bar equipped the damper. The bar and damper are made of an austenite stainless steel (SUS304), which is a non-magnetic material. Vibration characteristics of boring bar are evaluated by means of impulse hammering method. Firstly, the geometry of dynamic damper is discussed which has higher damping ratio. Secondly, the effects of magnetic force are examined. Furthermore, the vibration rigidities are compared to those of commercial bars. The obtained results are as follows. The damping ratio at a given overhang of boring bar is dominated by mass ratio and natural frequency ratio between bar and damper. The length or diameter of spring constructed dynamic damper must make longer or thinner as the overhang lengthens. The largest damping ratio obtained is 18.5%, which equals the maximal value of commercial product.
