中文摘要：

采用变频加热的方法对塑料挤出机进行加热，建立相应的数学模型，并详细地阐述了其原理和工作方案。说明变频控制在PLC控制中的实现方法，设计基于VC6．0和PLC的温度闭环控制系统。通过上位机系统输出的温度曲线表明，变频加热的方法提高了加热速度保证了控制精度，利用上位机控制的优势，进行参数化设计，控制灵活，操作简单。

英文摘要：

The frequency conversion heating was adopted for heating in plastic extruder. Mathematical model was established, the principle and working scheme was described. The method of frequency conversion was explained when used in PLC. The temperature closed-loop control system was designed on the basis of VC6.0 and PLC. The temperature curve of computer system showed that the heating speed was increased and precision was ensured by frequency eonversion heating. The interface was designed man-friendly,operationed and controlled easily.