不同金属夹杂物对曲轴钢加工过程中刀具磨损及表面完整性的影响

Investigation on Tool Wear and Surface Integrity during Machining Crankshaft Steel with Different Metallic Inclusion

研究了六种含有不同夹杂物曲轴钢的车削性能,开展了车削刀具磨损试验,并在线采集切削力,刀具后刀面磨损VB值和工件表面粗糙度每20min记录一次。通过扫描电镜和能谱仪对刀具磨损机理进行研究,同时用光学显微镜测量表面完整性。刀具磨损初期以磨粒磨损和涂层剥落为主;刀具进入稳定磨损阶段,出现崩刃和积屑瘤,崩刃引起的破损是刀具磨损加剧进而失效的主要原因。以氧化铝形式存在的铝夹杂物在车削中加剧了破损,使刀具寿命和表面完整性恶化。选用锰夹杂物作为固体润滑剂,延长了刀具寿命,提高了曲轴钢的切削性能。在曲轴钢的车削过程中,表面完整性与刀具磨损密切相关,刀具磨损越小,表面粗糙度越低,加工质量越好。

This research focuses on turning performance of six kinds of steels with diverse inclusions.Tool wear tests are conducted while cutting forces are measured online.Tool flank wear (VB) and surface roughness are recorded per 20 minutes.Tool wear mechanism is investigated by SEM and EDS.Surface integrity is measured by optical microscope.Abrasive wear and coating disbonding dominates during the initial wear stage.Notch wear and built-up edge appears when the tool enters a stable wear stage.At last,chipping caused by notch wear dominates the tool wear hus leads to tool failure.Aluminum inclusions in form of aluminum oxides,increases micro-chipping during turning and deteriorates the tool life and surface integrity.Manganese inclusions,acting as a solid lubricant,prolongs the tool life and increases the machinability of the steels.Surface integrity is closely connected with tool wear during turning of the crankshaft steels.The tool with minor wear produces a lower surface roughness and smoother surface texture.