变阻流区厚度的T型模具流道设计方法

Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》

麻向军

Abstract： T die is usually used to manufacture the sheet or casting film of thermoplastics.In order to im-prove the thickness uniformity of product manufactured using T die with constant radius manifold and con-stant thickness choke zone , increasing the radius of the manifold or decreasing the thickness of the chokezone was usually adopted to improve melt exit flow rate.However , a larger manifold diameter would prolongthe melt residence time although it is beneficial to decreasing extrusion pressure , while a thinner chockzone would increase the extrusion pressure although it is beneficial to shortening the melt residence time.A new structure of flow channel with decreasing radius of manifold and increasing thickness of choke zonealong the width of flow channel is proposed in this paper to shorten the melt residence time and reduce theextrnusion pressure based on the analysis of melt flow characteristics in flow channel.Under the condition of uniform melt exit flow rate along the width of the flow channel , the differential equation of thickness ofchock zone is deduced based on rheology , which can be solved by numerical method and fitted in design.Compared with flow channel with constant radius manifold and constant thickness choke zone , the proposedflow channel with thickness-varying chock zone and radius-varying manifold is beneficial to decrease theextrusion pressure and shorten the melt residence time significantly. Using the proposed flow channel in 'Tdie design , the melt residence time can be shortened further without increasing extrusion pressure signifi-cantly by the dimension and shape design of manifold , while the extrusion pressure can be adjusted to meetextrusion requirement without increasing melt residence time by the length and thickness design of chokezone.

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