铝基复合材料超精密加工中的刀-屑摩擦磨损性能及模型研究

通过金刚石PCD刀具对非连续SiC增强铝基复合材料的超精密车削加工试验,考察了刀具第二切削变形区(刀具前刀面-切屑间)的摩擦磨损性能,并提出了相应的模型;采用爆炸式快速落刀装置制备出切屑根并分析了积屑瘤的影响因素;采用原子力显微镜对PCD刀具的刃口磨损形貌进行观察,并分析其磨损机理.结果表明:在超精密切削加工非连续增强铝基复合材料的过程中,前刀面仍然有极小的楔型积屑瘤产生;铝基复合材料的摩擦磨损性能明显优于铝合金,且当SiC增强相达到最佳体积分数(20%～25%)时,其摩擦磨损性能最佳;从刀具的耐磨性角度考虑,在超精密加工非连续增强铝基复合材料时适宜采用金刚石刀具.

Wear Model and Characteristics between Cutting Tool and Chips in Ultraprecision Machining of SiC Reinforced Aluminum Composites

Wear model and characteristics of the second cutting deformation zone,that is,between the rake face of cutter and chips were investigated by carrying out diamond PCD cutter ultraprecision machining test of SiC noncontinuous reinforced aluminum composites,and measuring analysis with atom force microscope(AFM) and scan electronic microscope(SEM).Chip-roots were obtained with the device of quick dropping tool,and effects of wedgy Built-up Edge(BUE) were analyzed.Micro-morphologies of worn PCD cutter edge were observed with AFM,and wear mechanism was analyzed.Results show that very small BUE is still produced on the rake face of cutter in the process of ultraprecision turning of the SiC noncontinuous reinforced aluminum composites.The wear resistance of SiC aluminum composites is clearly better than that of aluminum matrix,tribological performance of the composite is optimized when adding 20%~25% volume fraction SiC reinforcement.In addition,in the process of ultraprecision machining of aluminum composites,diamond cutting tools are the best candidate.