DYNAMICS IN HIGH SPEED MACHINING

摘要

Since the development of new machines, drives and cutting tool materials with high resistance due to temperature and wear the significance of High Speed machining in production has increased and enables machining at high material removal rates. Some basic investigations which can be used in process design to determine optimum cutting conditions are shown in the presented paper. In order to describe chip formation at high cutting speeds, model experiments with single cutting edge engagements were conducted. By means of this model experiments each single contact between workpiece and tool can be described in terms of time and place by cinematic considerations. Different steel types are used as workpiece material. A force measurement system with a high stiffness and a algorithm to calculate real cutting forces instead of a superposition of cutting forces and inertia forces were used to get information about the transferred energy in the cutting process. A decisive decrease of the cutting forces was found which cannot be correlated with a change of the chip formation mechanism from continuous chips to serrated chips. For the different materials, the chip formation mechanisms turned out to be different. Continuous chips could only be observed using materials with low mechanical properties. Due to the higher mechanical properties a change in the chip formation mechanism could be observed. The formation of serrated chips was decisively influenced by the cutting speed and the machined material. During the examination, the frequency of chip segmentation was measured by means of acoustic emission. Frequency of chip segmentation increased linear corresponding with increasing cutting speed.