Influência da preparação das arestas de corte de brocas helicoidais no processo de furação

Abstract

The cutting edge preparation is a process which has drawn attention from the tool’s manufacturing and refurbishing industry due to specialization to its benefits specially to tool useful life. This process results in a major competitive advantage to those who have the knowledge of its application and, for this reason, it is kept as a trade secret. As far as the twist drills are concerned, the scarcity of information is even greater, due to the high complexity of the tool and process itself. This dissertation presents the results of the influence of the preparation of the twist drills cutting edges microgeometry alteration in steel drilling process SAE 4144M quenched and tempered steel with 38 HRC. The manual brushing process was used to prepare tools with rounded edges and manual filing process was used to prepare tools with chamfered edges. Several features from the machined parts were measured, such as diameter, roundness, position deviation, roughness of the obtained holes, hardness and microhardness of specimens, feed force and torque of the drilling process, assessment of type and shape of the chips from the process. The results showed that the edges preparation process increases the wear resistance of the tool and thereby increases its useful life significantly, especially for tools with rounded edges. In addition, it influences the surface integrity of the obtained hole (circularity and roughness) and the hardness of the region near the wall of the obtained hole. There was no significant difference in torque between the analyzed geometries, however the thrust force was lower for the sharpened tool without any edge preparation.