【作者】 万熠；

【导师】 艾兴；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2006， 博士

【摘要】 高速切削加工技术是先进实用的制造技术，正成为切削加工的主流，具有强大的生命力和广阔的应用前景。然而，高速切削刀具的工作条件比在普通切削加工下更为恶劣，刀具失效过快一直是制约高速切削加工广泛应用的一个关键问题。高速切削时，刀具具有不同于普通切削的失效机理，需要新的理论和方法来进行研究。航空航天行业是高速切削技术应用最为广泛的行业之一，在高速铣削航空铝合金时遇到了刀具失效等方面的许多问题。本文针对高速铣削航空铝合金7050-T7451的刀具失效机理和刀具寿命进行了系统研究。 高速切削时切削加工工艺对刀具的早期失效有着重要的影响，研究了高速铣削航空铝合金时刀具的合理选用和高速切削共振区的判定方法。根据变速度单因素实验测出切削力和表面粗糙度，提出了一种具有可操作性的判断高速切削共振区的方法。研究表明，这种方法和理论分析一致，从而证明了其可行性。 研究了高速铣削7050-T7451时的切削变形程度、切屑形成和剪切角。指出高应变、高应变率和高温是高速切削不同于普通切削的特点。通过快速落刀实验研究了切屑根部形貌，剧烈扭曲的滑移线间接证明了粘结磨损存在。通过实验分别研究了高速车削和高速铣削7050-T7451时的切屑形态及变化规律。 研究了整体涂层硬质合金刀具和超细晶粒硬质合金可转位刀具高速铣削航空铝合金的铣削力及其变化规律。首先利用七参数法对圆弧头立铣刀进行了几何建模，然后建立了两种切削刀具的力学模型，最后分别对整体式和可转位式圆弧头铣刀进行了切削力正交实验，建立了铣削力经验公式。 研究了高速铣削航空铝合金7050-T7451时的切削温度。提出了高速铣削航空铝合金切削温度的“导热反求”方法，利用红外热像仪和数值模拟方法确定了铣削过程中的切削温度。通过研究发现切削温度随切削速度提高而升高，到了1000m／min后升高幅度变缓，证明M．C．Gee曲线比Salomon曲线更具合理性。通过高速断续车削实验得到了切削与空切时的温度差，为求解刀具所受到的热应力提供了基础数据。 建立了基于高速切削过程热力耦合不均匀强应力场的刀具失效理论，并将其运用到分析高速铣削航空铝合金的刀具磨损和刀具寿命研究中，利用数值模拟方法研究了热力耦合不均匀强应力场对高速铣削刀具失效的影响。通过研究发现，热力耦合不均匀强应力场的等效应力远远小于超细晶粒硬质合金的抗拉强度，刀具因高周循环应力冲击而逐渐破坏，表明应力疲劳对刀具失效起到重要作用。通更多还原

【Abstract】 High speed machining (HSM) is one of the advanced manufacturing technologies and is going mainstream because of its many advantages. However, the short tool life is one of the great obstacles in the application of HSM because of severe cutting conditions. As failure mechanisms of cutting tools in HSM is different with those in conventional machining, new theory and research method should be presented. Although HSM was firstly used in Aeronautics & Astronautics industry, there are still many problems in tool failure especially in high speed machining monolithic parts. Tool failure mechanism and tool life have been studied in high speed milling of aluminum alloy 7050-T7451.High speed machining process plays an important role in tool failure. The appropriate selection and proper use of cutting tools have been researched as well as the determination of resonance regions in high speed milling of aluminum alloy. A new and maneuverable method to determine the resonance regions has been presented according to the fact that vibration will result in the increase of cutting forces and roughness of machined workpiece. With this method, just a single factor experiment should be conducted in which cutting speed is variable. Experimental result is consistent with theoretical analysis.Research on mechanism of cutting deformation is the basis to study cutting force, cutting temperature and tool wear. The degree of deformation, chip formation and shear angle theory have been studied. It is pointed that high strain, high strain rate and high temperature are the main characteristics of high speed machining process. It is found that the intense distort of sliding lines indicates the existing of adhesion wear. The chip patterns have been observed by experiments in high speed turning and milling respectively.Milling forces in high speed milling of aluminum alloy 7050-T7451 have been researched by theoretical analysis and experimental approaches with coated solid cemented carbide cutting tool and uncoated superfine grain cemented carbide inserts. Geometry modeling of radius end milling cutting tool is established by seven-parameter method presented by Altintas. The cutting force models of above two kinds of cutting tools have been established. Also the empirical formulae have been更多还原