基于制品壁厚中心基准尺寸的挤出模头设计理论研究

分析了聚合物PVC型坯的离模膨胀原因,在挤出模头口模缝隙设计及主体尺寸计算中,引入了离模膨胀比、膨胀牵伸综合系数,论述了基于制品壁厚中心的挤出模头设计方法,比以制品外表面为基准设计口模尺寸的方法误差更小,在此基础上推导出型材主体部分口模缝隙及尺寸的计算公式,并通过计算实例进行了验证。

Theoretical investigation on design of extrusion die head based on the characteristic dimension of product wall thickness center

The die swell cause of polymer PVC workblank was analyzed. The die swell ratio, compositive factor of expansion and drawing was indroduced in designing the mouth- die gap and calculating the main size. The design method of extrusion die head based on the product wall thickness center was presented. The calculation method will have a smaller er？ror result compared to that with outline as benchmark to calculate the mouth-die size. On the basis of it, the calculation formula for the mouth-die gap of sectional material main part was derived.