AN INVESTIGATION OF VARIABLE SPINDLE SPEED FACE MILLING FOR TOOL-WORKSTRUCTURES WITH COMPLEX DYNAMICS .2. PHYSICAL EXPLANATION

Part 2 of this paper focuses on the explanation, both on theoretical g rounds and through model simulations, of why the technique of variable spindle speed machining is an effective tool for increasing the quali ty and productivity of machining operations. In particular Parr 2 expl ains why, by disturbing the regenerative and forced vibration excitati on frequencies which generate large amplitudes of vibration during con stant speed machining, variable speed machining has the potential to r educe the vibration of the tool-work system and be robust with respect to the cutting process dynamics. The explanation is based on the work done by the cutting forces, the chip load variation, fool-work displa cements, cutting forces, and workpiece surface error generated by both constant and variable speed machining. By investigating the effects o f regeneration and forced vibration during variable speed machining on the vibration of tool-work systems having different cutter diameter-t o-workpiece width ratios, it has been shown that variable speed machin ing is also robust with respect to the geometry of the tool-work syste m. This work concludes that variable speed machining is safer to use t han constant speed machining when the effects of the tool-work dynamic s and geometry on the vibration of the cutting process are hard to det ermine.