摘要塑料已经发展成为最重要的基本原料之一，它被广泛应用于各个领域，而塑料挤出机是塑料生产和加工的重要设备。在塑料制品的挤出过程中，温度的控制极其重要，它直接决定了塑料制品的质量和性能。59213

本文通过分析挤出机的工作原理，研究温度控制的算法，设计了以可编程控制器PLC为核心，根据温度偏差的大小采用积分分离的PID控制算法。该算法结构简单，实时性比较强，而且可以较好地在PLC上实现。并且把PID算法的输出与加热器在一定时间内的通电时长进行转换，同时把它们的输出量的占空比进行比例调节，从而实现对加热功率的控制，使普通继电器能够代替复杂的可控硅执行装置，降低了成本。

根据提出的温度控制算法，对系统的硬件和软件分别进行了设计。通过软件的编程，证明了该算法的可行性。基于该方法的挤出机温度控制系统结构简单，成本低，控温精确。

毕业论文关键词：塑料挤出机，温度控制，可编程逻辑控制器，比例积分微分算法

Abstract Plastics have developed into one of the most important basic raw materials. It is widely used in various fields, and plastic extruding machine is one of the important equipment for plastic production and processing. In the process of plastic extrusion, temperature control is extremely important, it directly determines the quality of plastic products.

This paper analyzes the methods and principles of extruder temperature control. Study of the temperature control algorithm, design the PLC programmable controller as the core, according to the size of the temperature deviation separation integral control algorithm of PID control parameters. The algorithm is easy to implement, the real-time performance is strong, and better implementation on PLC.And convert the output of the PID algorithm to electrify time relay in a certain time interval, while keeping the output duty cycle is proportional regulators so as to realize the control of heating power, enable common relay to replace complex SCR device, reducing costs.

According to the temperature control algorithm, separately carried on the design of hardware and software of the system. Through software simulation, prove the feasibility of the algorithm. The extruder temperature control system based on the method of simple structure, low cost, accurate temperature control. 

Keywords: temperature control, plastic extruding machine, PID, PLC

 目录

第一章 绪论 1

1.1 挤出机温度控制的国内外发展现状 1

1.2 选题的目的和意义 2

1.3 课题的研究内容 3

第二章 塑料挤出机温度控制系统的介绍 4

2.1塑料挤出机温度控制概述 4

2.1.1塑料挤出机结构及工作原理 4

2.1.2 温度对塑料挤出生产系统的影响 5

2.2 塑料挤出机温度控制的特点 6

2.3 塑料挤出机温度控制算法 7

2.3.1开关控制 7

2.3.2 比例控制 7

2.3.3 PID控制 8

2.4 PID控制在PLC上的实现算法 9

2.4.1 PID算式的离散化 9

2.4.2采样周期的选择 10

2.5 加热功率控制研究 10