纸基蜂窝零件高速加工装夹系统中填料与回收方法的研究
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摘要
与传统的固持方法相比,基于磁场与摩擦学原理的蜂窝固持方法,具有固持稳定可靠、使用方便、无环境污染、成本低等优点。使用这种固持方法,可大大提高蜂窝芯零件的加工效率与加工精度。作为这种固持方法中的一项关键技术,数控填料与回收方法的研究对这项新型工艺技术的工程化应用有着非常重要的现实意义。本文通过理论分析与试验研究相结合的方法,对纸基蜂窝零件固持系统中的填料方法以及铁粉分离方法等问题进行了系统的研究。全文共分七章:
     第一章首先阐述了蜂窝复合材料的发展概况及其在飞机制造中的应用状况。然后在总结分析国內外现有纸基蜂窝芯零件固持方法、给料方法和物料分离方法的基础上,提出了进行填料方法和物料分离方法研究的意义、目标及主要内容。最后给出了论文研究的主要内容和论文撰写的体系结构。
     第二章从理论上研究散体物料的流动性与物料自身属性以及外界振动强度之间的定性关系。并通过实验方法研究了80目铁粉通过小孔流出时,其流动性与孔径以及振动加速度的关系、流出体积与流动时间的关系以及流量与振动频率、振幅的关系,并给出了其间的变化关系曲线图。通过理论计算设计出一种满足使用要求的螺管式电磁开关,并应用实验方法研究了电磁吸力与气隙间距以及线圈中电流强度之间的关系。这些实验数据为振动料斗的设计奠定了基础。
     第三章研究了振动料斗、驱动系统以及预压紧装置的结构组成和工作原理。根据给料工况要求和有关铁粉流动性以及流量的试验结果,设计出一种可实现定量控制功能的振动给料斗。以某型号飞机结构件中蜂窝芯零件为填料对象,充分利用现代设计理论与方法,设计出一种满足使用要求的龙门式驱动机构。为了保证在填料过程中蜂窝表面与磁性平台完全贴合,提出一种气动预压紧方案。
     第四章首先针对蜂窝芯零件的结构特点,从曲面整体连续性和可加工性的角度出发,提出一种带有复杂过渡区域的组合曲面整体G~1连续模型的建立方法。然后以蜂窝零件的数学模型为基础,结合填料工况要求,提出一种填料区域的规划方法以及基于正四边形区域划分的填充区域位置优化确定方法。
     第五章根据填料系统的结构特点和运动精度要求,研究并开发了填料装置的控制系统和相应的控制软件。并应用经典控制理论和仿真软件MATLAB对X、Y方向运动机构的动态响应特性和稳定性进行了详细讨论。
     第六章根据铁粉与切屑物理特性的差异,采用一种基于气固两相流原理的铁粉与切屑混合物分离技术。在分析铁粉与切屑在分离管道转弯处发生分离条件的基础上,详细研究了设计物料分离系统所需各项参数的选取和计算方法。
    
    浙江大学博士学位论文
     第七章在总结全文工作和创新点的基础上,指出纸基蜂窝零件固持系统中填
    料与铁粉回收方法需要进一步研究和解决的问题.
     关键词:纸基蜂窝,固持系统,散体颗粒,铁粉,振动给料,定量控制,填
    料区域规划,控制系统,物料分离
    本论文研究得到国防军工项目的资助.
Compared with conventional fixture methods, the proposed method, based on magnetic fields and tribology theory, has many excellent characteristics such as credible fixture, convenient operation, pollution free, low cost, etc. The machining efficiency and precision of paper honeycomb core part can be improved greatly through applying the method. As a key technology in the fixture system, study on numerical control feeding technology and recycling method is a very important work in order that the novel technology is used in practice. In this dissertation, by coalescing theory analysis and experiment study, feeding and recycling method in fixture system of paper honeycomb are studied systemically. Seven chapters are included in this dissertation:The state of the art in honeycomb composite material and its application in the airplane manufacturing are expounded firstly in chapter 1. Then the existed fixture methods of honeycomb, feeding and recycling methods are summarized. After that, the significance and purpose of studying on the feeding and recycling method are proposed. Finally, the main contents of this dissertation are summarized.The qualitative relationship between flow properties of bulk solids and its characteristics is studied in theory in chapter 2. Then quantitative relationship between vibratory acceleration and hole-size are studied when 80 meshes iron powder flow out from small holes. Furthermore, the relationship between discharges of iron powder and flow time, the relation between discharge rate and vibration frequency, and the relation between discharge rate and vibratory amplitude are also studied by means of experiments, and a graph representing the variational relation among these parameters is made. A solenoid electromagnetic switch is designed through theoretical calculation, then the relationship between magnetic force and air-gap distance, and the relationship between magnetic force and current intensity are studied by experiment. These experimental data are basis of vibratory feeder design.The component structure and working principle of vibratory feeder, driver system and pre-compaction equipment are developed in chapter3. A vibratory feeder that can control discharge of iron powder quantitatively is designed based on working conditions and experimental results. When the honeycomb core parts in a certain model plane are considered as the objects to be fed, a double housing driver is
    
    designed based on modern design theories and methods. In order to make the surface of honeycomb touch with the platform completely, a pneumatic pre-compaction project is presented.In chapter 4, with regard to the structure characteristics of honeycomb core part, a global G1 continuous compound surface model construction method is presented from the point of view of surface continuity and manufacturability. Then the planning method of feeding region is studied based on mathematic model of part and demand of working conditions. And an optimized selection method of feeding region is proposed.In chapter 5, the control system and control software of feeder are developed. By applying the classical control theory and simulation software MATLAB, the dynamic characteristics of motion along X and Y direction are described in detail.Based on gas-solid two-phase flow theory, a separating technology of mixture composed of iron and paper scrap is studied in chapter 6. Applying gas-solid two-phases suspended flow theory, the force condition is analyzed when two kinds of material separate at the corner of the pipe. Then the selection and calculation method of system design parameters is described detailedly.In chapter 7, systematical summary is given, and future work is put forward.
引文
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