Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metal cutting and machine tools > Program control machine tools, CNC machine tools and machining

Dynamic Characteristics Analysis and Optimization Design of Hydraulic System of Tray Automatic Exchange Device of Machining Center

Author WangWangLiang
Tutor ZhangGenBao
School Chongqing University
Course Mechanical Manufacturing and Automation
Keywords Tray Automatic Exchanging Device FTA Simulation AMESim software Test
Type Master's thesis
Year 2011
Downloads 159
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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.

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