Abstract
This paper describes the roundnesses of drilled center holes and the vibrations of workpieces and drills during center drilling. In the experiment, center holes of workpieces are machined with center drills fixed to the tailstock of a lathe. The work-pieces are held in a three jaws chuck (method I) and held between a headstock center and a drill itself (method II). The center hole profiles and the vibrations during drilling are investigated by using Fourier analysis. The obtained results are as follows : (1) In either workpiece holding method, lower odd-number-lobed components of the profile are remarkable compared with the other components. (2) The undulation on the profile has a close relation to the vibration during drilling. (3) The mode shapes of the vibration depend upon the workpiece holding methods. (4) The profile in case of method II contains larger undulation than that in case of method I.
