蜗轮箱体工艺及夹具设计(钻孔和镗孔）【全套含CAD图纸、文档说明书资料】
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钻孔
镗孔
工艺及镗孔钻孔夹具设计【
蜗轮箱体
镗孔钻孔
工艺及镗孔夹具设计【
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机械与电气工程学院 毕业设计（论文）外文翻译 所在学院： 班 级： 姓 名： 学 号： 指导教师： 合作导师： 年 12 月 9 日原文：DCS-Based Process Control Simulating SystemAbstract: A distributed control system (DCS) based on two-layer networks for experimental teaching is presented in this paper. Three sets of equipments are used as process objects with their parameters such as pressure, temperature, level and flow rate being controlled variables. This system has multiform training functions. Students can not only set up basic experiments about the process control, but can also design complicated control system. The result of 4 years use shows: it is an ideal engineering simulating system for students major in industrial automation. Key Words: DCS, process control, simulating system, experimental teaching, network 1.INTRODUCTIONControl education is an integral part of the communitys activities and one of its most important mechanisms for transition and impact. In 1998, the National Science Foundation (NSF) and the IEEE Control Systems Society (CSS) jointly sponsored a workshop in control engineering education which made a number of recommendations for improving control education . One of them is about experiments. Experiments continue to form an important part of a control education and projects should form an integral part of the curriculum for both undergraduate and graduate students . The idea of using distributed control system for process control emerged in the 1970s. Now it is widely used in manufacturing,chemicalindustry,papermaking, textile, food processing,power,etc.DCS integrating advanced computer, control, communications and CRT technologies has played an important role in raising technological level, reducing cost, and making production more flexible and integrated. So, it is very important to establish a DCS simulating system in university. We have set up the system in 2002. The system can bring more understanding of real-world problems to the students. 2.SYSTEM BUILDUPMost modern industrial process control system adopts two-layer network topological structure. The lower one- field bus comes close to the process and the upper one-Ethernet mainly locates inside control room. Such structure disperses control and centralizes management and operation. Our system bases just this structure with the benefits of letting students familiar with current industrial network control. As shown in Figure 1, our system consists of 16 operator stations, one I/O station and 3 sets of process equipments. 2.1 The Distributed Computer System From Figure 1 we can see that the distributed computer system is connected by two-layer networks. The monitoring network is implemented via 10M/100M pen Ethernet. The TCP/IP protocol is used. The buses connected by I/O stations and operator stations are information channels for plantwide supervision and control. According to the specifications of a process, the web server linked to Internet can also be set to achieve remote monitor. This network is arranged redundantly so the system proves reliable. The field network interconnected by I/O station and its I/O modules uses Profibus-DP and transmits a variety of information and parameters in real time. The operator stations are general-purpose PCs. They act as engineering stations when used for off-line configuration, so 16 students can program at the same time. While for on-line use the students can monitor and control the process on these PCs. The I/O station is a domestic product developed by Beijing Hollysys Co., Ltd. Its design adopts standardization and modularization.The I/O station based on high-performance microprocessors and mature control algorithms can response as soon as possible to the internal and external events. It has 5 local modules i.e. two FM148 analog input cards, one FM151 analog output ard, one FM161 digital input card and one FM171 digital output card. Each card has particular microprocessor responsible for its control, test, calculation and diagnosis, thus, enhancing its selfcontrol level and dramatically improve its reliability and safety. The station or modules can be shifted without disturbance in case of trouble. Therefore, the system is able to control in real time and with high quality. 2.2Process Equipments Process control is an important course of automatic major . After learning the theories in the classroom, the students have an eager for digesting and understanding. The control community has a strong history of impact on many important problems and industry involvement will be critical for the eventual success of the future directions. How to imitate industrial process is an important concern. We have built 3 sets of equipments representing pressure process, level process, temperature and flow rate process individually. The three sets of equipments can also be used for normal instrumentation control or direct digital control. All the connections are wired to the panel, so does the I/O station. The process equipments can be flexibly linked to different controller by plug contacts on the panels. There are different kinds of transducers installed on the process to provide a variety of signals such as tempera-ture, level, pressure and flow rate .These signals are analog inputs to DCS. The final operating elements include electric heater, switching components and control valves . DCS outputs analog or digital signals to the elements. The combination of the process equipments with the distributed computer system explores the frontiers of control, including increased use of computing, communications and networking, as well as exploration of control in application domains 3.SOFTWARE CONFIGURATION AND OPERATIONIn the computer-control field, it has been customary to overcome some of the programming problems by providing table-driven software. A user of the DCS is provided with a configuration package that allows the user to generate a DCS system simply by configuring, so very little effort is needed to program. The package providing device, database, control scheme, graph and report forms configuration is run off-line on the engineering station. Configuration of the DCS is implemented from up to down by conforming to hardware structure. It is divided into the following 5 steps : Devices registration to configure system hardware, including: the number of I/O stations or operator stations along with their network addresses and each I/O stations hardware such as data transmission card, I/O card;Database configuration to define signal points and parameters set;Control scheme configuration classified as conventional configuration which provides many control blocks like feedback, cascade, ratio and self-defined one that is programmed in real time control language similar to BASIC;Graph configuration to make various pictures such as survey, standard display, adjust, control, trend, flow chart, alarm displayed on high-resolution color CRT and compound windows more abundant and menu-function more live; this configuration to configure diagrams for operator to monitor and control the process in real-time; Report forms configuration to provide statistic report of the process. Before running the software, all the configurations must be compiled, linked and downloaded to the operators where several networked PC sharing the overall workload are able to monitor and control all aspects of process from a variety of live displays and friend interactions. Or the operator will run the system downloaded last time. The operator is extended with flat sealed film keyboard, touch screen, and global mouse to let operations easier. Through the man-machine interaction the process data can be collected, analyzed, recorded and controlled in real time; the system structure and configure loops can be modified on line; local breakdown can be fixed on line. Once the process is abnormal, the hardware will self diagnose and inform the operator stations that personnel around the field find the breakdown and that the indicator lamps on cards on I/O station shows the fault location. Such dual means of indication together with breakdown alarm and hot plug-in plug-out make it possible to fix breakdown on line and to run system safely and reliably. 4 .EXPERIMENTAL PROJECTS Our DCS simulating system can train 16 students at the same time. The training functions are versatile from hardware and software configuration to complicated system design and debug. By I/O station 11 inputs from the 3 sets of equipments are measured and controlled, 7 control valves and 1 electric heater of the processes are manipulated in real time to implement temperature, pressure, level and flow rate control, breakdowns are detected and the system is maintained. Live measured values and status indications reveal the current situation. Process operators monitor and control the long-distance processes from their own consoles . The students operate the system as if they are in the real-world industrial automation. The flow chart of temperature and flow rate control sys-tem is shown in Figure 2. T1, T2 are measured temperature of the inner and outer water tank. FT1, FT2 are flow rate of the water into the inner and outer tank. WVL1 and WVL2 are two outputs from the I/O station to change the open range of the valves. ZK is a switch for turning on or off the electric heater. This system control is made up of 2 single variable closed-loops (T1-control and FTI Control),1cascade (T1-T2) and 1proportion(FT1-FT2) loop.All loops adopt normal PID which parameters can be dynamic adjusted from the operator station. The four control loops and main chart of the system can be easily shifted by pressing the buttons on the bottom of the graph as shown in Fig 2. 5 .CONCLUSIONThe result of 4 years use for both undergraduate and graduate shows: experimental training is especially efficient to help students understand the technique of industry process, the dynamic characters of the control system and to improve students ability to operate and control the process. The convenient hardware connections make the DCS teaching system easily operated and the effortless software configuration renders different control algorithms implemented flexibly. Besides basic experiments about the process control, students have also designed complex control system to meet stricter product specifications. 译文：基于DCS过程控制仿真系统摘要本文提出的是一个建立在实验教学双层网络上的分布式控制系统（DCS）。其中配备三套设备，用于监测实验过程对象中自身的流量、水平、温度的次数变量。该系统具有多种形式的培训职能，学生不仅可以设立有关控制程序的基本实验，而且还可以设计复杂的控制系统。经过4年的使用结果表明：DCS过程控制仿真系统是一个非常理想的工程模拟系统，我们可以利用它做工业自动化的学习研究。 关键词：DCS、过程控制，仿真系统，实验教学，网络1. 绪论控制系统的教育机构是社会体系中的组成部分，在有举足轻重的位置，它是一个重要的转变和影响机制。在1998年，美国国家科学基金会（NSF）和电气和电子工程师控制系统协会（CSS）联合举办教育控制工程教育研讨会，本提出了如何改善控制系统的教育机构的若干建议，其中就有关于实验的提议。研究人员表明DCS过程控制系统应当始终作为控制系统学习的重要组成部分，应作为对本科生和研究生课程的组成部分。上世纪70年代，分布式控制系统就出现在过程控制应用之中。到现在，它被广泛用于制造，化工，造纸，纺织，食品加工，电力等各种领域。分布式控制系统结合了先进的计算机，控制，通信和CRT技术，为生产技术水平不断提高，减少成本起到重要的作用，使得生产更具有灵活性和综合性。如此看来，我们在大学期间，建立一个DCS仿真系统是非常重要的。在2002年，我们成功建立了这个系统。该系统的建立，可以让学生更多的了解实际遇到的问题。2. 系统建立大多数现代工业过程控制系统都是采用两层网络拓扑结构。系统采用一个较低的现场总线来关闭进程，用一个以太网来控制整个系统操作，使用这种分散式结构控制和集中管理和运作。我们的系统就是基于这样的机构上，可以更有利于学生熟悉目前的工业控制。如图1，我们的系统包括16个操作站，一个I / O站和3套加工设备2.1分布式计算机系统我们从图1的分布式计算机系统可以看出，分布式计算机系统是由2层网络连接组成。该监测网络是通过10M/100M以太网实施控制，并在TCP / IP协议下使用。系统由总线连接各个I/O站点，操作员站连接所有信息渠道，可以在整个系统范围进行监督和控制。依据整个过程的结构，在网络服务器链接到互联网的条件下，也可以设置实现远程控制。该网络采用冗余安排，以便使得系统绝对的可靠。外部网络通过I/O总站连接到系统，并在I/O模块中使用现场总线段落准确的传输各种信息和参数操作站作为工程总站，通过主机的控制，在不在现场的情况下，可以让16名学生同时进行工程训练，而且学生可以使用电脑程序通过网络对这些操作进程监视和控制。该系统I/O控制站是基于北京和利时发展有限公司的产品，它的设计采用标准化和模块化。该I / O站的基于高性能微处理器和成熟的控制算法，能尽快回应系统内部和外部的各种操作。它由5个本地模块组成，即两个FM148模拟输入卡，一FM151模拟输出卡，一卡FM161数字输入和一个FM171数字输出卡。每个卡都具有其特定的微处理器，负责不同的控制，测试，计算和诊断，由此来加强系统自身的控制水平，大大提高了它的可靠性和安全性。在糟糕的情况下，这样的控制站可以一直启动无干扰模式。由此可见，这样的系统可以保证高品质的且非常准确的控制2.2工艺设备过程控制是一个非常重要并且艰巨的工程。学生通过课堂理论学习之后，需要进一步去消化和理解。而这个控制系统在过去很多年里影响到很多重要事件，而在未来的发展方向主要与各个行业的合作，这将是最终取得成功的关键。如何去模仿工业过程是一个重要的问题。我们已建立3个独立设备，分别用于代表压力加工设备，工艺水平，温度和流量水平。并且这3套的设备也可用于正常仪表控制或直接数字控制。所有设备都通过线路连接到控制面板，同时也连接到I/O站点，并且可以自由的与控制面板上的任何插头连接。在过程控制系统中安装有各种不同的传感器，用于监测如温度，真实姿态，液位，压力和流量，给控制站反馈多种信息。这些信息通过模拟输入到DCS，然后通过电热水器，开关元件，和控制阀等操作元件控制整个过程，形成一个反馈系统。然后集散控制系统输出模拟或数字信号的元素。这套控制系统设备是与分布式计算机控制系统结合
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