Programming spindle speed variation in turning
A mathematical model for the turning process is de- veloped, which considers the oscillations of technological machining system (TMS) in a 3D space, along all three coordinate axes simultaneously. The model accounts for the influence of natural feedback on the depth, feed and cutting speed; moreover, the effect of machining by chatter marks is introduced into the model by two directions depth and feed. It is established that the main factor, which determines the origin of regenerative oscillations, is the machining by chatter marks. That is why a change in the spindle speed with the help of the SSV option (Spindle Speed Variation) on the machine tool with CNC leads to a change in the trail frequency and its noncoincidence with the natural vibration frequency of TMS, which calms the system.The created applied simulation software makes it possible to conduct a purposeful search for the best parameters of harmonic law when changing the spindle speed for each particular machining case. We propose as the criterion the minimum time of oscillation damping by amplitude per one entire revolution of the billet. Thus, a procedure is developed and a tool is created for programming the variable speed of the spindle in the turning operation on the machine tool with CNC. We experimentally proved effectiveness of the proposed solution.