高速铣削镍基高温合金复杂薄壁零件关键技术研究

发布时间：2018-04-03 20:05

本文选题：镍基高温合金　切入点：高速铣削　出处：《哈尔滨理工大学》2016年博士论文

【摘要】：镍基高温合金能在高温氧化气氛及燃气腐蚀条件下工作,可承受复杂应力,是现代航空发动机、发电汽轮机中叶轮叶片类零件不可缺少的材料。由于镍基高温合金的强度高,塑性大,导热系数低,加工表面硬化显著、切削力大、刀具磨损快,属难加工材料,所以镍基高温合金材料加工效率低,产品表面质量和精度不稳定。除了镍基高温合金材料难加工之外,镍基高温合金薄壁零件材料去除率大,又属于复杂曲面,薄壁且曲率变化剧烈,刀具走刀方向不断发生转向,极易引起刀轴振动,在零件加工表面产生竖纹或过切现象。如复杂薄壁零件叶片的表面微形貌及纹理对整个叶片的动力传递效率起着决定性的作用,从而严重影响叶片使用性能,致使叶片报废。因此,本文以镍基高温合金复杂薄壁零件数控加工为背景,通过理论分析、切削试验,揭示高速加工镍基高温合金复杂薄壁零件的相关加工机理及切削稳定性相关技术,解决航空航天行业复杂薄壁零件切削加工的共性基础科学问题,为镍基高温合金零件的高效加工及减少刀具磨损提供有力的技术支持,为镍基高温合金叶片类零件稳定性加工提供较为准确的理论依据。针对锯齿形切屑对切削过程的影响,进行镍基高温合金铣削实验,探讨不同切削参数下锯齿形切屑形成规律,揭示绝热剪切现象。通过光学显微镜观察切屑组织,得到绝热剪切带内材料组织形态的演变过程,提出锯齿形切屑形成由形变带锯齿形切屑-转变带锯齿形切屑一系列转变。最后研究切削参数对锯齿形切屑几何特征的影响规律,为切削条件的选择提供理论依据。针对镍基高温合金薄壁零件材料去除率大,刀具使用寿命与加工效率之间的矛盾,开展高速铣削镍基高温合金刀具磨损规律的研究。通过铣削实验获得切削速度对刀具磨损影响较大,随着切削速度的提高,前刀面磨损形式为多种磨损机制共同作用,后刀面磨损主要为沟槽磨损,并且切屑毛边对刀具的冲击造成沟槽磨损加剧。结合仿真结果提出加工表面硬化也会对刀具的沟槽磨损产生影响。上述工作为铣削镍基高温合金材料时减少刀具磨损、提高刀具使用寿命提供理论依据。针对镍基高温合金复杂薄壁零件加工插补算法中设计曲线与刀具运动扫描体包络面之间存在误差,如在叶片叶缘处,存在刀具路径转接问题,将四元数法引入到五轴加工的刀具运动设计中,建立四元数节点光顺法,优化刀具运动路径,结合POWERMILL软件提供的曲面投影加工方式,采用驱动曲面方式规划叶片精加工刀具路径轨迹,改善叶片叶缘的过切现象,提高复杂曲面铣削的加工精度。针对镍基高温合金薄壁零件侧铣过程中的切削振动问题,进行了切削力预报及切削动力学研究。在镍基高温合金薄壁零件加工过程中考虑其动态特性的时变性,建立侧铣加工时滞动力学模型,提出辐角稳定性判别法,实际加工效果表明,采用此方法获得的稳定切削参数域具有一定的实用性,并与传统二维Lobe图稳定性判别法相比较,一致性好,并且简单实用,易于工程化。通过综合考虑镍基高温合金复杂薄壁零件的制造关键问题,采用理论分析、切削仿真和切削试验相结合的方法,在镍基高温合金复杂薄壁零件加工切屑形成特征、刀具磨损机理、刀具运动设计及稳定性极限预测方面进行研究。研究可为镍基高温合金复杂薄壁零件的切削加工技术推广及应用提供理论依据和技术支撑。
[Abstract]:Nickel based high temperature alloy can work in high temperature oxidation atmosphere and gas corrosion conditions, can withstand complex stress, is the modern aviation engine, the impeller blades in the turbine generator parts indispensable materials. Because of nickel based superalloy with high strength, high plasticity, low thermal conductivity, surface hardening significantly, cutting force, rapid tool wear is difficult to cut materials, so the nickel base high-temperature alloy material of low processing efficiency, surface quality and precision. In addition to nickel based alloy material is difficult to machining materials, parts nickel based high temperature alloy thin removal rate, and belongs to the complex surface, thin wall and curvature change, tool cutting direction constantly changed, extremely easy to cause the cutter shaft vibration, resulting in vertical grain parts processing surface or over cut phenomenon. Such as dynamic surface of complex thin walled parts leaf micro morphology and texture of the whole blade transfer efficiency A decisive role, which seriously affected the blade performance, causing the blade scrapped. Therefore, based on the nickel based high temperature alloy thin-walled parts CNC machining as the background, through theoretical analysis, cutting test reveals the machining mechanism of thin-walled parts and cutting stability of complex technology for high speed machining of nickel based superalloy, solve the aerospace industry complex common basic scientific problems of thin-walled parts machining, provide strong technical support for tool wear nickel based high temperature alloy parts machining efficiency and reduce, and provide a theoretical basis for the accurate processing of nickel based superalloy blade stability. The serrated chip effect on cutting process, milling experiments of nickel based superalloy and to investigate the different cutting parameters of serrated chip formation, reveal the adiabatic shearing phenomenon. Through the optical microscope chip group Fabric, get the evolution of adiabatic shear band of materials within the organization, the chip is formed by deformation sawtooth chip change with serrated chip, a series of changes. The zigzag influence finally the effects of cutting parameters on thegeometry characteristic of serrated chip, provide a theoretical basis for the selection of cutting conditions for. Nickel based high temperature alloy thin-walled parts of the material removal rate, the contradiction between tool life and machining efficiency, carry out the research of high speed milling tool wear of nickel based superalloy. Through milling experiments of cutting speed on tool wear have greater impact, with the increase of the cutting speed, the former flank wear wear mechanism for a variety of forms mainly, the flank wear and cutting groove wear, impact on tool chip edge caused by groove wear increased. According to the simulation results of machining surface hardening will groove on the cutting tool Impact wear. The work for the milling of nickel based superalloy materials to reduce tool wear, provide theoretical basis for increasing the service life of the cutter. The error between the nickel based high temperature alloy thin-walled parts machining interpolation algorithm design curve and motion of the tool scanning body enveloping surface, as in the blade edge, existing tool path transfer problem that will be four yuan number method is introduced into the design of five axis machining tool movement, the establishment of four yuan in the number of nodes in the fairing method, the optimization of tool path, surface projection processing methods combined with POWERMILL software, driven by surface finishing machining tool path planning, improve the leaf margin of over cutting, improve processing the accuracy of complex surface milling. According to the cutting vibration problem of nickel based high temperature alloy thin-walled parts side milling process, the prediction and cutting dynamics research on cutting force in nickel. When considering the dynamic characteristics of modified machining process based high temperature alloy, a side milling time delay dynamics model, proposed criterion angular stability, show that the actual processing effect, stable cutting parameters obtained by using this method, the domain has a certain practicality, and discriminant method and the traditional two-dimensional Lobe map stability comparison, consistent good, and simple and practical, easy for engineering. The key problems of complex manufacturing thin-walled parts considering nickel based superalloy, by theoretical analysis, simulation method of cutting and cutting experiments combining the formation characteristics of the Ni based high-temperature alloy complex machining cutting, tool wear mechanism, limit cutter design and stability the prediction is studied. For the study of nickel based superalloy thin-walled parts machining technology popularization and application and provide a theoretical basis and technical support.

【学位授予单位】：哈尔滨理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG54

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