Abstract
The drill tip in a hole is considered to be equivalent to the journal of an externally pressurized partial bearing. In this report, taking account of the bending of drill shank due to the cutting force and oil-film force, the equilibrium attitude of drill tip in the hole is simulated by digital computer, and then the bearing characteristic, especially the oil-film force is investigated. The simulation results correspond reasonably to the experimental results of the former reports within quantitative deviations of 20-30%. The bearing characteristics depend on the supply pressure of cutting fluid, the neck-skew of drill tip, the shank length, the viscosity of cutting fluid and the work speed. Such characteristics can explain the behavior of drill tip and the accuracy of holes clarified in the former reports.
