背压对注塑工艺的影响

通过背压对不同类型塑料注塑工艺的影响试验，指出在一般注射成型背压压力范围内，背压压力的改变具有压力效应和温升效应的双重性，而且两者相互消长，并对传统的背压曲线提出新的见解。传统的背压曲线中塑化量随着背压的增加呈线性下降的关系，而实际生产中，是呈先升后降的关系，且对不同类型塑料的影响也是大小不一，因此在实际注射成型生产中应该慎重地结合其它工艺条件进行背压的调整。

EFFECT OF BACK PRESSURE ON INJECTION MOLDING TECHNOLOGY

By the experiments on the effect of back pressure on the injection molding technology of different types of plastics, it is demonstrated that the change of back pressure will result in a variation of melt pressure and melt temperature. Furthermore, it is found that the melt pressure and the melt temperature vary inversely. And the traditional back pressure curve is interpreted in a new way. According to the traditional back pressure curve, the plasticizing amount linearly decreases with the increase of the back pressure. While the practical results show that the plasticizing amount goes up with the increase of back pressure at the beginning stage and then goes down. Meanwhile, the plasticizing amount also depends on the type of plastics. So back pressure ought to be optimized in conjunction with other molding parameters in practice.