Análise de chatter no torneamento de aço endurecido utilizando o método de elaboração de diagramas de lóbulos de estabilidade

Abstract

Chatter is a self-excited phenomenon that affects manufacturing processes, which causes a poor surface quality in final pieces, excessive tool wear, waste of material and uncomfortable noise, causing financial loss and bad operation conditions to the operator. This phenomenon can be found in most traditional metal cutting processes. This study researches the occurrence of chatter in Turning operations for specimen of tool-steel class O ASTM A681-O1 using the development of Stability Lobes Diagram (SLD) in 6 different modellings of a metal Lathe considering 2 and 6 Degrees of Freedom (DOF) and rigid or flexible operation conditions. The investigation was based on adopting parameter obtained on the references and estimate some other to get the SLD in graphic of Depth of Cut alim versus the Lathe spindle speed n, after that, compare the parameters adopted in the four condition of cutting of the reference. It was found that for chatter identification processes through SLD, modelling can cause a serious impact in the results obtained, given that using a poor representative model, considering the Lathe a 2 DOF mass-spring-damper system in which the bed mass is the mass of the system, and the spring and dumping coefficients between the bed and ground are the system coefficients, the system was tagged as stable, being safe for chatter occurring. However, when considering the model as a 2 DOF mass-spring-damper system in which the tool plus tool holder mass is the mass of the system, and the spring and dumping coefficients between the tool plus tool holder and the turret are the system coefficients or considering a 6 DOF model dependent on each other, the system was tagged as unstable, in which the phenomenon might have occurred. Finally, one could be noticed that in orde to get a better surface quality in specimens, the author could use better parameters of cutting, like a higher spindle speed or a lower depth of cut.