薄壁曲面零件数字化制造优化技术研究

发布时间：2018-08-22 17:07

【摘要】：随着薄壁曲面零件的广泛应用,薄壁曲面零件的设计及加工已成为数字化设计和制造(CAD/CAM)开发与应用领域的热点。薄壁曲面零件形状复杂加工周期长,刚性差容易变形,变形补偿困难,装夹难度很大。薄壁曲面零件的数控加工是数字化制造领域的研究重点,本文就面向薄壁曲面零件的数控编程技术、数控加工工艺和曲面夹具进行了深入的研究。针对传统数控刀路轨迹不连续、或刀路轨迹连续但尖角转接过多等严重制约高速加工切削性能的瓶颈问题,本文提出了面向高速加工的复合型螺旋刀轨生成方法。以高速加工必须的切削稳定性为目标,将复杂自由曲面细分为“平坦曲面”、“顶部平面-陡峭面”、“顶部平坦曲面-陡峭面”和“复合型陡峭曲面”等几大类型,根据各自不同的形状特点和工艺特点,分别开发不同结构的复合型螺旋刀轨,可以满足各种复杂形状自由曲面高速加工的苛刻要求,有效解决了高速加工中的切削颤振和振动,薄壁曲面零件的加工效率和加工精度有明显提高。针对曲面逆向构建过程中常见的扭曲现象,以构建变形补偿曲面为核心,将传统变形补偿技术、逆向工程技术和数控5轴CAM技术的最新成果有效结合起来,提出面向薄壁曲面变形补偿的“样条曲线拟合技术优化法”、“曲面重构技术优化法”和“基于曲面三维法向补偿的CAM编程法”,实现了曲面误差补偿和数控编程一体化,在曲面变形补偿精度和CAM编程效率方面都有较大的提高。针对薄壁曲面零件工装设计方面缺乏高效曲面自适应夹具的问题,研制了面向环形薄壁毛坯的多点式环形曲面自适应夹具以及面向薄壁曲面箱体零件的多点式曲面自适应真空夹具。多点式曲面自适应夹具综合了机械结构和液压结构的优点,与传统夹具相比接触点数量成倍增加,在结构上实现了多点浮动功能,形状适应性强装夹效率高,可以满足自动化生产线对自由曲面零件快速装夹的要求。有限元分析和实际使用效果表明自适应夹具能够满足自动化生产线对自由曲面快速装夹的要求。论文的研究结果为薄壁曲面零件高速切削技术、薄壁曲面三维变形补偿技术和多点式曲面自适应夹具的应用提供新的方法和工具。
[Abstract]:With the wide application of thin-walled curved surface parts, the design and machining of thin-walled curved surface parts has become a hot spot in the field of digital design and manufacturing (CAD/CAM) development and application. The shape of thin-walled curved parts is long, the rigidity difference is easy to deform, the deformation compensation is difficult, and the clamping is very difficult. Numerical control machining of thin-walled curved parts is the research focus in the field of digital manufacturing. In this paper, the NC programming technology, NC machining technology and surface fixture for thin-walled curved surface parts are deeply studied. Aiming at the bottleneck problems such as the discontinuity of traditional NC cutter path, or the continuous path of cutter path but too much angle transfer, which seriously restricts the cutting performance of high speed machining, this paper presents a new method for the generation of compound helical cutter track for high speed machining. Aiming at the cutting stability of high speed machining, the complex free-form surface is subdivided into "flat surface", "top plane-steep surface", "top flat surface-steep surface" and "composite steep surface". According to their different shape characteristics and technological characteristics, the compound helical cutter rails with different structures are developed, which can meet the harsh requirements of high-speed machining of various complex free-form surfaces, and effectively solve the cutting chatter and vibration in high-speed machining. The machining efficiency and precision of thin-walled curved parts are improved obviously. Aiming at the common distortion phenomenon in the process of surface reverse construction, the traditional deformation compensation technology, reverse engineering technology and numerical control 5-axis CAM technology are effectively combined with the construction of deformation compensation surface as the core, and the new results of the traditional deformation compensation technology, reverse engineering technology and numerical control 5-axis CAM technology are effectively combined. The "spline curve fitting optimization method", "surface reconstruction technology optimization method" and "CAM programming method based on surface 3D normal compensation" for thin-walled surface deformation compensation are proposed, which realize the integration of surface error compensation and NC programming. The accuracy of surface deformation compensation and the efficiency of CAM programming are greatly improved. In view of the lack of efficient adaptive fixture for thin-walled curved surface parts in tooling design, The adaptive multi-point curved surface fixture for ring thin-wall blank and the multi-point surface adaptive vacuum fixture for thin-walled curved box parts are developed. Multi-point curved surface adaptive fixture combines the advantages of mechanical structure and hydraulic structure. Compared with the traditional fixture, the number of contact points is multiplied, the multi-point floating function is realized in the structure, the shape adaptability is strong and the clamping efficiency is high. Can meet the automatic production line for freeform surface parts fast clamping requirements. The results of finite element analysis and practical application show that the adaptive fixture can meet the requirements of the automatic production line for fast clamping of free-form surfaces. The research results of this paper provide new methods and tools for the application of high speed cutting technology of thin-walled surface parts, three-dimensional deformation compensation technology of thin-walled surface and adaptive fixture of multi-point curved surface.
【学位授予单位】：江苏大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG659

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