【作者】 毕雪峰；

【导师】 刘永贤； Alain MOLINARI； Guy SUTTER； Gautier LIST；

【作者基本信息】 东北大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 金属切削作为最基本的加工方式,被广泛应用在制造领域的各行各业。金属切削过程中,刀具和切屑交界面剧烈的摩擦、较高的温度和压力使刀具前刀面产生月牙洼磨损,它在一定程度上改变了切削参数,并降低了刀具的强度,最终导致刀具失效,因此月牙洼磨损机理和模型的研究是非常必要的。另外,切削过程中切削材料在第一变形区经历剧烈的塑性变形,对其研究能够进一步揭示切削过程中的变形机理,并为探索材料在高温高应变率条件下的本构方程提供一种新的研究方法。本文使用无涂层硬质合金刀具切削低碳钢工件材料,并依此建立了刀具前刀面月牙洼磨损模型,分析了切削材料在第一变形区的塑性变形以及切屑形态对刀屑接触长度的影响,论文的主要研究内容如下：(1)根据刀具月牙洼磨损实验,建立了一个适用于普通速度切削的月牙洼磨损经验模型,该模型表述了磨损率与切削过程变量之间的关系。利用切削有限元仿真计算了磨损模型中重要的参数——刀屑交界面上的温度分布。采用回归分析的方法拟合了磨损模型中的系数。该模型预测了相似切削条件下月牙洼的磨损轮廓,并分析了月牙洼磨损轮廓上不同磨损机理所占的比例。(2)依据高速切削实验,提出了针对高速切削加工的月牙洼磨损模型,它能够准确预测刀具失效前任意时刻的月牙洼磨损轮廓。使用气动弹道切削系统获得了高速切削过程中切削区的温度场,并依此提出了一个与月牙洼磨损轮廓相对应的刀屑交界面温度模型,为磨损模型中温度参数的确定提供了依据。采用回归分析的方法计算了磨损模型中的系数。(3)为了研究切削材料在第一变形区的塑性变形情况,基于气动弹道切削系统的高速正交切削实验,获得了切削材料上流线的变形轨迹；把一个通用的流线模型创新性地应用到金属切削中用来描述切削材料的塑性流动过程,并计算高速切削时切削材料在第一变形区的速度、应变率和应变分布。此外,使用相同的流线模型研究了普通速度切削中切削材料在第一变形区的塑性变形,并分析了两种切削条件下塑性变形的差异。(4)在月牙洼磨损的研究中发现,低进给的高速切削产生了较高的刀屑接触长度。针对这个问题,使用气动弹道切削系统,获得了高速切削时较大进给范围内的切屑形态和刀屑接触长度,并依据实验结果定性的分析了切屑形态对刀屑接触长度的影响。更多还原

【Abstract】 Metal cutting, as the most basic manufacturing processes, are widely used in varieties of modern manufacturing enterprises. During the cutting process, severe friction, high temperature and pressure occurring in tool-chip interface cause crater wear on tool rake face. This leads to the change of cutting condition, decrease of the tool intensity, and finally tool failure. Therefore the investigation of crater wear mechanism and model is quite necessary. In addition, workpiece suffers severe plastic deformation in primary shear zone in machining. Research on the plastic deformation is significant for basic understanding of cutting process, and provides some insight for exploring material constitutive law at high temperature and high strain rate.This research focuses on crater wear modeling, evaluation of plastic deformation in primary shear zone and influences of chip morphology on tool-chip contact length when uncoated cemented carbide tool cutting low carbon steel. The dissertation includes the following aspects:(1) Based on crater wear experiments, an empirical crater wear model for conventional speed machining is established to describe the relationship between wear rate and process variables. Finite element simulation for machining process is used to obtain temperature distribution on tool-chip interface, which is the important parameter in wear model. Regression analysis can determine the coefficients in wear model. The proposed crater wear model gives good prediction to crater wear profile in similar cutting conditions, and also shows the contribution percentage of different wear mechanism along crater profile.(2) With high speed machining experiments, crater wear model for high cutting speed is established. It can accurately predict crater wear profile with cutting time before tool fail. According to the temperature distribution on tool-chip interface observed by using ballistic set-up, a temperature model corresponding to crater profile is proposed to determine temperature parameter in wear model. Regression analysis can determine the coefficients in wear model. (3) In order to analyze plastic deformation in primary shear zone, deformed flow lines on cutting material are obtained from high speed orthogonal cutting experiments performed by ballistic set-up. A general streamline model is innovatively used to present plastic flow of cutting material in high speed machining. Accordingly velocity, strain rate and strain distribution of cutting material in primary shear zone are calculated based on the streamline model. Furthermore, this streamline model is also applied to determine the plastic deformation in conventional speed machining. The differences of plastic deformation between conventional and high speed machining are analyzed.(4) High tool-chip contact length with low feed is found in the investigation of crater wear in high speed machining. Therefore, a series of experiments with large range of feed are carried out in ballistic set-up to record chip morphology and tool-chip contact length. The influences of chip morphology on tool-chip contact length are quantitatively analyzed.更多还原