Influência do ângulo de posição secundário da ferramenta, raio de ponta e lubrificação na usinagem em presença de aresta postiça de corte

Abstract

This work investigates the influence of tool end cutting edge angle and tool nose radius on surface finish of AISI 1045 steel machined under built-up edge conditions. Surface roughness was evaluated measuring the Ra parameter and analysis of the geometry of the machined surface was carried out in the scanning electron microscope. To assist this work, the three main machining forces components were measured during cutting using a Kistler piezoelectric dynamometer. High speed Steel tools with the same substrate composition and geometry but varying end cutting edge angle, between 1° to 45°, were used. To study the effect of tool nose radius it was used three coated cemented Carbide tools from class ISO P25 with same geometry but different tool nose radius (0,4mm. 0,8mm and 1,2mm). Ra measurement and scanning electron microscope analysis showed that improved surface finish can be achieved by reducing the end cutting edge angle. The effect of a neat oil lubricant with EP additives applied at very low rate (12 ml/min) was also studied. The lubricant improved surface finish and its effect depends on the end cutting edge angle. The effects of this angle and the very low volume of lubricant suggest a mechanism of lubrication where the oil does not need to penetrate into the chip tool interface avoiding built up edge formation to improve surface finish. The lubricant acts on the machined surface close to the tool nose radius.