【作者】 王望良；

【导师】 张根保；

【作者基本信息】 重庆大学 ， 机械制造及其自动化， 2011， 硕士

【摘要】 托盘自动交换装置(Tray Automatic Exchange Device)是加工中心的主要功能部件,其功能主要是实现待加工工件与已加工工件之间的自动交换,可以在加工的同时装夹零件,实现加工时间与辅助时间的重合。托盘自动交换装置是集机、电、液、计算机技术高度一体化的关键功能部件,借助它可以将加工中心集成到柔性制造单元(FMC)或柔性制造系统(FMS)。随着工业技术的不断进步和发展,加工中心的发展趋势是高效率、高精度、高自动化、高柔性和高可靠性,同样的,对托盘自动交换装置的静动态稳定性、可靠性、精确性及高效性提出了越来越高的要求。托盘自动交换装置由机械系统、液压系统与控制系统组成,结构非常复杂,为了提高其性能,除了运用传统的分析技术外,运用计算机仿真技术对液压系统动态特性进行分析也具有重要意义,计算机仿真技术不仅可以预测系统性能,减少设计时间,还可以对所涉及的系统进行整体分析和评估,从而达到优化系统性能、缩短设计周期和提高系统稳定性的目的。论文的主要工作如下:在第二章中,首先,基于几种不同的交换装置驱动机构的介绍,重点对液压驱动交换装置的结构和工作原理进行了分析和研究;定义了托盘自动交换装置故障树分析与液压系统动态特性分析以及优化设计三者之间的关系,同时运用故障树分析(FTA)方法对托盘自动交换装置潜在故障进行了定性分析,并提出了改进措施。在第三章,介绍了液压系统建模仿真软件AMESim的基本特性和主体软件AMESim的使用方法,根据托盘自动交换装置力(力矩)平衡方程、动力学方程和信号控制原理建立了液压系统执行装置的等效模型、液压缸缓冲等效模型和液压系统控制信号等效模型,同时运用该软件建立了托盘自动交换装置旋转和升降液压系统的仿真模型;分析了不同工件质量对液压系统执行装置动态特性的影响,分析了节流口直径对托盘自动交换装置液压系统执行装置动态特性的影响,包括液压缸缓冲节流口直径和回路单向节流阀开口直径对液压系统执行装置动态特性的影响。对造成交换架振动和来回晃动以及噪声等故障的主要原因进行了定量分析,包括液压冲击的本质、原因以及液压冲击最大值的计算,并提出了预防和减小液压冲击的措施。在第四章,研制和开发了托盘自动交换装置试验平台,制定了托盘交换装置动态特性试验方案和步骤,对仿真模型和参数设置的正确性进行了验证,同时验证了可以通过调节液压缸缓冲节流口直径大小来改善交换架交换动作的平稳性,提高交换架动态品质;接着,针对托盘自动交换装置液压系统存在的缺陷和不足,作者进行了优化设计,提出了采用三位四通电液伺服阀进行闭环控制,建立了改进后的液压系统仿真模型,并对系统动态跟踪误差和稳态误差进行了仿真分析,证明了该液压系统能够满足托盘自动交换装置交换平稳、准确、可靠等性能要求。在运用故障树分析法对托盘自动交换装置故障进行定性分析的基础上,采用仿真分析和试验研究相结合的技术手段,对托盘自动交换装置主要故障进行了定量分析,得出了一些重要的性能曲线,对了解托盘自动交换装置的交换速度、动作时间及液压系统压力和流量变化等参数以及液压系统各个液压元件间相互影响等起到重要的作用,同时为托盘自动交换装置液压系统优化设计提供了理论依据,从而为进一步完善和提高现有托盘自动交换装置交换平稳、轻便、准确和可靠等动态性能奠定了基础,可以为现场操作人员和调试人员提供了定量参考。更多还原

【Abstract】 Tray Automatic Exchanging Device (TAED) is one of the main function components of Machining Center, and its main function is to realize the automatic exchange between the workblank and finished workpiece, to clamp parts while the workpiece is in processing, so it can be realize the processing time and auxiliary time coincidence. TAED is key functional components highly integrated by the machine, electricity, liquid, computer technology. With the help of it Machining Center can be integrated into flexible manufacturing unit (FMC) or flexible manufacturing system (FMS). With the industrial technology unceasing progress and development, the development trend of Machining Center is high efficiency, high precision, high automation, and high flexible and high reliability. Meanwhile, more and higher demand of TAED with static and dynamic stability, reliability, accuracy and efficiency are put forward. TAED is comprised of mechanical system, hydraulic system and control system, and its structure is very complex. In order to improve its performance, in addition to use traditional analysis technology, it also has important significance to analyze the dynamic characteristics of hydraulic system by using computer simulation technology, because computer simulation technology can not only predict the system performance, reduce design time, it can also analyze and evaluate integrally the involved system, so as to achieve some purposes ,including the optimization system performance, shorten the design cycle and improvethe system stability. This paper, the major work is as follows:In the second chapter, first of all, based on the present development situation at home and abroad of TAED, and structure and working principle of TAED with exchange workbench driven by hydraulic are analyzed and researched in depth. The relationships among fault tree analysis, hydraulic system dynamic characteristic analysis and optimization design is defined. Meanwhile, the failures of TAED are analyzed with the fault tree analysis (FTA) method, and measures for improvement are put forward.In the third chapter, the basic characteristics of the hydraulic system modeling simulation software AMESim and usage of main software AMESim are introduced. According to force (moment) balance equation, dynamic equation and signal control principles, the equivalent model of hydraulic system actuator, the hydraulic cylinder cushion equivalent model and the hydraulic system control signal model are established. At the same time, simulation model of rotation and lifting hydraulic system of Tray Automatic Exchanging Device are established by using the software. The influences on hydraulic system dynamic characteristics of actuators from the different workpiece quality and the throttling mouth diameter are analyzed, including buffer throttling mouth diameter of hydraulic cylinder and one-way throttle valve opening diameter of hydraulic loop. The main reasons of exchange bracket vibration, sloshing and noise are found out by quantitative analysis, including the essence and cause of the hydraulic impact phenomenon, and the maximum value of hydraulic impact is calculated, finally, some measures of prevention and reduction are put forward.In the fourth chapter, test platform of TAED are designed and developed, the tray automatic switching device, and through making test plan and steps of dynamic characteristics of TAED, the correctness of simulation model and parameter set are demonstrated. Meanwhile, by adjusting the hydraulic cylinder buffer throttling mouth diameter values to improve steadiness, and enhance dynamic quality of exchange bracket are proved by test. Then, base on defects and the insufficiency of hydraulic system of TAED, the optimization design is proposed by the author, the suggestion of using a three-four electro-hydraulic servo valve to realize closed loop control is proposed and put to use, the improved hydraulic system simulation model is established, and the system dynamic tracking error and steady-state error are analyzed by simulation, finally, the ability which the hydraulic system can meet the TAED to exchange smooth, accurate, reliable performance requirements is proved.on the basis of qualitative analysis of TAED faults by using the fault tree analysis, the quantitative analysis of TAED faults are carried out with technical means by combining the simulation analysis and experimental research, and some important performance curves are obtained, which is very important to understand the exchange speed, action time, some parameters changes of hydraulic system pressure and flow, and even mutual influence among various hydraulic components of hydraulic system, and which provide some theoretical basis for hydraulic system optimal design, thus which lay a solid foundation to further enhance and improve the exchange smoothly, lightweight, accurate and reliable, and which can provide operators and debugging personnel with some quantitative references.更多还原