高速铣削难加工材料时硬质合金刀具前刀面磨损机理及切削性能研究

Research on Wear Modes and Mechanism of Carbide Tools in High-Speed Milling of Difficult-to-Cut Materials

采用涂层硬质合金刀具和细晶粒硬质合金刀具对超高强度合金钢(硬度>50HRC、抗拉强度σb>1.4GPa)和马氏体不锈钢(硬度>30HRC)等难加工材料进行了干式高速端面铣削试验;选择刀具寿命作为刀具切削性能的评价指标,利用X射线能谱仪和扫描电子显微镜分析了硬质合金刀具前刀面的磨损形态、磨损机理以及刀具的切削性能.结果表明:在难加工材料的高速铣削过程中,涂层硬质合金刀具主要失效形式为前刀面磨损,细晶粒硬质合金刀具主要失效形式为前刀面月牙洼磨损与剥落;2种刀具的主要磨损机理均为扩散磨损和氧化磨损.对细晶粒硬质合金刀具而言,在考虑刀具材料与工件材料适配性的基础上,必须利用合理的刃口强化处理来降低磨损初期的刃口微崩刃倾向.

High-speed dry face-milling tests were conducted for difficult-to-cut ultra high strength alloy with σb > 1.4 GPa and hardness 50HRC and martenstic stainless steel with hardness 30HRC, using (Ti,Al)N coated carbide tool and fine grain carbide tool, respectively, on a DMU-70 evolution 5-axle processing center. The morphologies of the worn fake faces of the cutting tools at different cutting conditions were observed using a scanning electron microscope, while the elemental compositions in the central worn area were determined using an energy dispersive spectrometer, which were aiming at revealing the wear mechanisms of the cutting tools and examining the cutting performance and lives of the cutting tools. It was found that the carbide tools were dominated by rake face abrasive wear, adhesion wear, diffusion wear, and chemical wear, in cutting the difficult-to-cut materials at high-speed, which were accompanied by the spalling of the coating on the rake face to expose the carbide substrate and the chippings of the cutting edges. The (Ti,Al)N coated carbide tool with a higher Al content in the coating had better cutting performance, and it was imperative to introduce proper reinforcing for the fine grain carbide tool so as to reduce its micro-chipping at the initial wear stage.