基于PLC的包装机控制系统

长春工业大学学士学位论文 I 摘 要 包装是产品进入流通领域的必要条件，而实现包装的主要手段是使用包装机械。近年来，随着全球经济的快速发展，各国人民的生活水平不断提高，食品、建材等工业发展越来越快，各个行业对自动包装设备的需求越来越大。但是，我国包装行业起步较晚，与国外的包装行业存在着很大距离，包装设备结构简单，技术落后，因而造成生产效率低下，物料严重浪费，能源耗费大。 本此设计主要介绍了一种以PLC（可编程控制器）为控制核心的自动包装控制系统。在包装过程中，通过称重传感器测量物料重量信号并利用PLC的PID功能对进料门（电动阀）开度进行控制，控制原则是设定重量与过程变量的偏差越大则电动阀开度越大，反之偏差越小电动阀开度越小。这样一来就使得物料称重更加精确，大大地提高了物料的利用率，更重要的是提高了生产效率，也就为企业创造了更多的价值。 另外，本系统的自动化程度较高，节省了劳动力的投入，并且精度较高，可靠性良好，相信会有良好的发展前景。

关键词：PLC（可编程控制器）；PID；自动包装 ABSTRACT

The packing is the essential condition that the product enters the current distribution realm, but realizes the packing principal means uses the packaging machinery. In recent years, along with global economics' fast development, various countries' people's living standard enhanced unceasingly, industrial developments such as food,building materials industry are getting quicker and quicker, each profession is getting bigger and bigger to the automatic packaging equipment's demand. But, our country start to be late in the profession of packing, and has the very great distance with the overseas packing profession, the equipment of packing to be simple, the technology is backward, thus causes the production efficiency to be low, the material wastes seriously, the energy consumes in a big way. This design mainly introduces an automatic packaging control system that take the PLC （programmable logic controller） as the core of control. During the packing process, 长春工业大学学士学位论文 II to measure the material weight signal through the Weighing Sensor and use the PID of PLC to control the opening of gate （Electrically operated valve）， The control principle is the set point and the process variable deviation is bigger, then the opening of Electrically operated valve is bigger, Otherwise the deviation smaller Electrically operated valve's opening is smaller. Thus the material weighing is more precise, on the other hand, it will raise the utility rate of material up greatly, and the most important point is that it will raise the production efficiency, also has created more values for the enterprise. Moreover, this system's automaticity is high, it save the investment of labors, and it has the high precision and the good reliability, believed that can have the good prospects for development.

Key Words: PLC （Programmable Logic Controller）： PID： Automatic Packaging

目 录 第一章 绪 论 ............................................................................................................. 5 1.1选题背景及意义 ...................................................................................................... 5 1.2 包装机械行业的现状及发展趋势 ......................................................................... 5 1.2.1 我国包装机械行业现状 ............................................................................... 5 1.2.2 目前我国包装机械行业发展的共性问题 ................................................... 5 1.2.3 我国包装行业未来的发展趋势 ................................................................... 3 1.3 自动包装设备的市场分析 ..................................................................................... 3 1.4可编程控制技术的现状 .......................................................................................... 4 1.5可编程控制技术的发展趋势 .................................................................................. 5 1.6 PLC与其它工业控制系统的比较 .......................................................................... 7 1.6.1 PLC与继电器控制系统的比较 .................................................................... 7 1.6.2 PLC与单片机控制系统比较 ........................................................................ 8 1.6.3 PLC与计算机控制系统的比较 .................................................................... 8 长春工业大学学士学位论文 III 1.6.4 PLC与集散型控制系统的比较 .................................................................... 9 1.7 PLC在包装机械上应用的可能性和前景 .............................................................. 9 第二章 系统方案设计 ................................................................................................... 11 2.1系统方案选择 ........................................................................................................ 11 2.1.1 系统组成 ..................................................................................................... 11 2.1.2 系统工作原理 ............................................................................................. 12 第三章 PLC（可编程控制器）的选择 ........................................................................ 14 3.1 PLC的选择 ............................................................................................................ 14 3.1.1 S7-200系列PLC的主要特点及功能 ........................................................ 14 3.1.2 S7-200系列PLC的结构组成 .................................................................... 16 3.1.3 S7-200系列PLC的数据 ............................................................................ 17 3.1.4 S7-200系列PLC的寻址方式 .................................................................... 17 3.1.5 程序中几个关键存储器的功能 ................................................................. 17 3.2 S7-200系列PLC CPU型号选择 ......................................................................... 18 3.2.1 CPU 226型的技术指标 .............................................................................. 18 3.2.2 S7-200 CPU 226型PLC的外型 ................................................................ 18 第四章 其它元器件选择 ................................................................................................. 20 4.1 模拟量扩展单元模板的选择 ............................................................................... 20 4.1.1 EM235模块的技术指标 ............................................................................. 20 4.1.2 EM235模块的接线端子说明及接线方法 ................................................. 20 4.1.3 EM235模块的数据字格式 ......................................................................... 21 4.1.4 EM235模块的校准 ..................................................................................... 22 4.1.5 EM235模块的输入设置 ............................................................................. 22 4.1.6 EM235模块的寻址 ..................................................................................... 23 4.2 称重传感器的选择 ............................................................................................... 24 4.2.1 称重传感器选型 ......................................................................................... 24 4.2.2 PS-W5悬臂梁式称重传感器的技术特点及技术指标 .............................. 24 4.2.3 PS-W5悬臂梁式称重传感器的外形及尺寸 .............................................. 25 4.3 称重变送器的选择 ............................................................................................... 25 4.3.1 称重变送器选型 ......................................................................................... 25 4.3.2 PT350C型称重变送器的技术指标 ............................................................ 26 4.3.3 PT350C型称重变送器的外形及尺寸 ........................................................ 26 4.4 电动调节阀的选择 ............................................................................................... 27 4.4.1 电动调节阀选型 ......................................................................................... 27 4.4.2 西门子SKC62型电动调节阀的主要技术指标 ....................................... 27