关键词: 18CrNiMo7-6钢, 高速切向车铣, 表面粗糙度, 残余应力, 传统车削

Abstract: In order to improve the anti-fatigue performance of 18CrNiMo7-6 gear steel, high-speed tangential turn-milling experiments were conducted. Results show that with high-speed tangential turn-milling, the three-dimensional surface roughness value Sa are close to those with grinding. The influences of workpiece rotating speed nw and milling cutter rotating speed nc on Sa are significant. The Sa decreases with the increase of nc, and increases with the increase of nw. There are residual compressive stresses on the machined surfaces of high-speed tangential turn-milling(up milling). The nc and axial feed fa have significant effects on surface residual stress. With the increase of nc, the axial residual stress σx and the tangential residual stress σy show the trends of increasing at first and then decreasing, and with the increase of fa, σx and σy decrease significantly. The maximum residual stress appears on the machined surfaces, decreases gradually within 40~60 μm thickness from the machined surface and then stabilizes. The fa has the greatest overall impact on the surface integrity and the surface integrity deteriorate rapidly with the increase of fa. Under the orthogonal test conditions of high-speed tangential turn-milling, the optimal test parameter combination obtained is as nc=6500 r/min, nw=75 r/min, fa=0.02 mm/r, radial depth of cut ap=0.1 mm. Under the conditions of optimal cutting parameters, the Sa is as 0.30 μm, σx is as -400.5 MPa, σy is as -415.9 MPa, and the depth of residual stress affected layer is as 60 μm. The surface integrity with high-speed tangential turn-milling is better than that with conventional turning. The cutting method herein provides a better machining method for machining external cylindrical surfaces.

Key words: 18CrNiMo7-6 steel, high-speed tangential turn-milling, surface roughness, residual stress, conventional turning