Influência das condições dinâmicas de usinagem no torneamento sobre a integridade superficial de um aço endurecido

Abstract

Several authors have dedicated themselves to investigating the dynamics of machining operations from different scopes. This type of study is especially valuable when it comes to finishing conditions, as the vibrations in process can significantly affect the surface integrity of the machined components. Turning of steels in the hardened state has gained ground in the metalworking industry as a substitute for abrasive processes. In this case, in fact, monitoring vibrations and controlling different roughness parameters are extremely important, as they can even influence the mechanical behavior of the components in question. This work contains an investigation about the influence of some machining conditions on the vibration of the tool and the surface integrity of the part in hard turning. For this, a specimen of tool steel for hot working type H13 was quenched and tempered made in segmented laps. The experimental procedures are divided into two stages: preliminary tests and new tests. In the former, a conventional lathe was used, a negative tool and, as influencing factors, the rotation of the spindle, the feed and the position of the lap in machining. The vibration signals, measured by piezoelectric tablets, were not able to infer any influence; on the other hand, the triaxial accelerometer indicated the influence of the advance. The roughness parameters, evaluated in a confocal microscope, in turn, showed the influence of the lap in machining. In the new tests, a CNC lathe, positive tool and piezoelectric accelerometers were used, which pointed to a greater influence of rotation and feed on the vibration of the tool. The roughness parameters show the effect of rotation and the position of the lap when machining. In view of the results obtained, it is concluded that this approach can consistently contribute to the improvement of process planning involving the machining of hardened steels. As suggestions for further work, we highlight the study of the influence of dynamic machining conditions on the mechanical behavior of machined components and the evaluation of vibration signals in the frequency domain to enable the identification of the occurrence of the chatter phenomenon.