精密注塑机保压压力的新型模糊自校正控制

A new fuzzy self-tuning method for controlling packing pressure of a high-accuracy injection molding machine

针对传统注射成型装备中保压压力控制精度不高的问题,提出采用伺服电机驱动定量泵的复合系统.伺服电机配合注塑机不同工艺过程输出相应转速,提高控制性能,消除高压节流.建立注塑机注射过程的数学模型,分析料筒内螺杆所受熔融态塑料的黏性摩擦力,提出一种新型模糊自校正(FST)控制算法.该算法在模糊控制收敛迅速,鲁棒性强的特点基础上,结合自校正控制算法,提高系统的响应速度,降低注塑机保压过程中的压力超调,消除系统的滞后.通过与传统PID算法对比实验结果表明,该算法能够提高保压压力的响应速度和控制精度,从而达到精密注塑的要求.

According to the poor packing pressure control accuracy of the traditional injection molding machines,this paper presents a new injection system using servo motor-driving fixed pump which can provide different speed with the given injection process.The mathematical models were established based on non-Newtonian fluid dynamics for the hydraulic system and the viscous force of melted plastic between the barrel and screw.Based on the theoretical analysis,a new fuzzy self-tuning（FST） method was proposed which combined the advantages of both the fuzzy control and the self-tuning control.The experimental data with packing pressure control showed that compared with the traditional PID algorithm,the FST algorithm has better performance with slighter overshooting,quicker response,shorter transient time and better control accuracy.