Estudo do processo de rosqueamento interno de ferro fundido cinzento utilizando diferentes sistemas de indexação de machos de corte

Abstract

The internal threading process is a machining process that is not commonly studied, as it mainly involves the use of dynamometers, which implies higher costs, but with the development of the technology of materials, cutting tools and CNC machine there is a need for a better understanding of this process, which implies in cost reduction. There are currently several indexing systems for cutting tools to be used in CNC machines, which when operating in combination with the cutting taps can greatly reduce the magnitude of the machining and torque forces involved in the process. There are few researches comparing the performance of these auxiliary devices to the internal threading process. Thus, the objective of this work is to investigate the behavior of three indexing systems for cutting tools, collet, collet with compensating table and floating head, combined with HSS cutting taps (M6 X 1.0). In order to better evaluate the performance of the systems during the dry-machining process the input conditions were varied: surface treatment of the cutting tap (Ni, TiN and TiCN) and workpiece material (gray cast iron: FC250, FC300 + Mo and FC300 + Mo (RG)). The experiments were carried out and the machining forces (Fx, Fy and Fz) and torque (Mz) were measured through the rotary or stationary dynamometers. It was observed that the surface treatment of cutting taps influenced the output variables more clearly only when using the collet. When machining the different types of gray cast iron no significant differences were observed between the results of the machining forces and torque. In general, the floating head is the cutting tool indexing system that obtained the best results, presenting, in the machining and return stages of the threading process, the lowest values of mean and standard deviation of the output variables. It is possible to say that the floating head of the evaluated systems is the one that most compensates the errors inherent to the process of internal threading with cutting taps.