金刚石切削黑色金属时刀具磨损机理的摩擦磨损试验

摘要

With the purpose of reducing the tool wear in a diamond cutting operation of ferrous metals and improving the machined surface quality and machining precision,the tool wear mechanism was studied.Experiments of the frictional wear between diamond and steel were performed to imitate the tool wear process in a practical diamond cutting.The wear morphology of workpiece surface,the changes in chemical composition of work samples,and the transformation of crystal structure of diamond specimens were detected by the Scanning Electron Microscopy(SEM),X-ray Energy Spectrometer(EDS)and the Raman Spectroscopy(RS).Then,the graphitized degree of diamond was proposed as a criterion for assessing diamond wear in tests.The experimental results reveal that the wear of diamond relies heavily on mechanical forces and temperatures,and less on the sliding speeds and carbon contents of materials in the test.The wear mechanisms of diamond in this frictional wear experiment include graphitization,diffusion wear and oxidation wear,and the graphitization is found to be the dominant wear mechanism for diamond wear.In addition,the graphitized degree increases up to 83％ with temperature rising of 15 ％.In conclusion,the tool wear mechanism should be considered comprehensively in condition of thermal-force coupling for further exploring technological measures with respect to reduce the tool wear.%为了降低黑色金属金刚石切削过程中的刀具磨损,提高表面加工质量和精度,对刀具磨损机理进行了研究.通过黑色金属金刚石摩擦磨损试验,模拟了实际切削过程中的刀具磨损行为;分别采用扫描电镜(SEM) 、X射线能谱仪(EDS)以及拉曼光谱仪(RS)对工件表面形貌、实验前后工件表面化学组分变化以及金刚石磨损表面的晶体结构转变进行了检测,同时提出了用石墨化程度作为试验过程中评价金刚石磨损的指标.试验结果表明:金刚石的磨损主要与机械力和温度有关,摩擦速度和工件材料中的含碳量对其影响相对较小;石墨化磨损、扩散磨损和氧化磨损等磨损机理共存,其中石墨化为导致金刚石磨损的主要原因.结合红外热像仪测温和热传导理论推算,近似获得了摩擦界面的真实温度,且随着温度升高15％,金刚石石墨化程度显著加剧83％.作者提出,应当综合考虑热-力耦合作用下的刀具磨损机理,以便进一步探寻抑制刀具磨损的工艺措施.