Dm. Rincon et Ag. Ulsoy, COMPLEX-GEOMETRY, ROTARY INERTIA AND GYROSCOPIC MOMENT EFFECTS ON DRILL VIBRATIONS, Journal of sound and vibration, 188(5), 1995, pp. 701-715
Increasing demand for better quality products and higher production ra
tes requires a more complete undersanding of drill dynamics. A transve
rse vibration model for drill bits is presented which includes the eff
ects of gyroscopic moments and rotary inertia. The model is used to de
monstrate the significance of these effects, and of complex drill geom
etries, on the natural frequencies of drill bit transverse vibration.
Advances in bearing technology are likely to increase spindle speeds t
o more than 60 krpm; a speed at which gyroscopic moments and rotary in
ertia were found to have significant effect. The most significant para
meter associated with complex drill geometries was found to be the num
ber of flutes. Using a comparable three or four fluted drill versus a
two fluted drill can increase the stiffness and, thus, the fundamental
frequency of the drill bit by as much as 54%. Other complex drill geo
metry parameters (material properties, web taper, coolant holes) were
not found to be as significant. (C) 1995 Academic Press Limited