硬质涂层滚刀切削高温区及失效机理研究

Study on the Heat Affected Zone and the Failure Mechanism of Hard Coated Hob

摘要: 采用阴极多弧离子镀技术在经过喷砂预处理的滚刀上制备了Al₆₆Cr₃₄N、Al₆₁Cr₃₉N硬质涂层，研究两种涂层滚刀切削加工齿轮的现场性能和失效机理。采用表面粗糙度测量仪、扫描电镜(SEM)、电子能谱(EDX)、3D光学显微镜、X射线衍射分析仪分析了涂层滚刀切削加工齿轮前后的粗糙度、表面形貌、磨损形貌，探讨了两种涂层滚刀切削失效的主要因素和统计规律。结果表明：两种涂层滚刀的失效均由涂层的黏着磨损及剥落所导致。切削后滚刀前刀面上出现了由切削高温区产生的氧化及氧化附着物产生的富氧变色条带。该变色条带的宽度与高温影响区范围大小呈正比。通过统计分析发现滚刀前刀面刀刃附近变色区(富氧区)的条带的宽度R_t与涂层的剥落V_b1和磨损宽度V_b2以及缺口数量N存在正相关性。因此滚刀切削后变色条带宽度可用于滚刀破损程度的综合评判参量。

Abstract: The Al₆₆Cr₃₄N and Al₆₁Cr₃₉N hard coatings were deposited onto M35 hobs by using cathode arc method. The morphology and failure mechanism of these coated hobs were investigated after field cutting machining gears. The roughness, surface and wear morphology of the coated hobs were analyzed by surface roughness measuring instrument, scanning electron microscope (SEM), elec-tron spectroscopy (EDX), 3D optical microscope and X ray diffraction analyzer. The failure mecha-nism of hobs was discussed. The results showed that the failure of the coated hobs was due to the deformation of cutting edges caused by adhesive wear and the coating spalling. After cutting, a discoloration bond appeared around the knife edge of the rake faces, which was induced by the heat affected zone during cutting, and absorption of oxidation products. The discoloration band width R_t is proportionally to the heat affected cutting zone. Furthermore, statistical analysis showed that the R_t of the used hobs was positively related with wear width V_b1 and coating spalling width V_b2 of the flank faces, and notch defect density N on the knife edges.