透明塑料板件注射压缩成型工艺的模拟研究.pdf

华中科技大学
士学位论文
透明塑料板什注射-压缩成型工艺的模拟研究
姓名:李毅超
申请学位级别:硕士
专业:材料加工工程
指导教师:张宜生
2011-01-11
华中科技大学硕士学位论文
摘要
随着塑料工业的迅速发展,人尺寸透明制件被越米越)泛的应用在汽作、航空等
领域,如制造车窗玻璃、大型机用透明複益件。山于其特殊的应用领域,这类制件
必须具有优良的力学、光学方而的性能。然而如何制定合理的工艺米制造这类尚质
量制件是一个亟待解決的问题。较早的研究发现,采用传统的注射成型工艺制造大
尺」透岄塑料平板件时,成型过程中型腔内压力、温度、纤维流线等参数的非均匀
分布会导致熔体内部残余应力的声生,使制件在成型结束后各部分,特别是边角部
位产生严重的收缩、翘出等现象,从而严重影响其力学、光学等方而的性能。为解
决这一问题,一种改进的注射一压缩成型方法受到关注,特别是在成型过程分析以及
工ど参数的优化方而。
j注射成型工艺相比,注射一压缩加I.に艺允许动模进行运动,使其在注射阶段
的末尾对熔体进行床缩。这一额外的步骤有利于控制熔体表而床力、温度的均匀分
布与冷却,从而从根本上消除制仲残余成カ与收缩不均的问题。然而困内对此项技
术的研究才刚刚起步,对成型过程中型腔内各参数的变化情况、工艺的使用范围与
注意事项都知之甚少。而这些信思对采用此种艺制定特定制件的加Iにに艺流程至
关重要。
本文采川计算机数值模拟技术,以正线性数偵模拟算法为某础,采川多物理场全
耦合计算的方法对不同形状成型件的注射一压缩成型工艺过程进行了全方位的模拟
仿貞分析,并将共成型结果传统注射成型I.艺进行了比较,得出以ド结论
使用注射一压缩成型工艺时,成型结東时型腔内的床力趋于?致;压缩速度、起
始模其张开高度、注射压缩转换时?分判会对型腔内压力曲线的幅值,变化刷烈程
度以及相位产牛影响
与传统注射成型工ど相比,注射-压缩工艺能够著降低制成件体积收缩率;成
型过稈中熔体的维流线长度与温度变化会对制件收缩率产牛.影响。较短的维流
线,较均匀的温度分布能够获得更小、更均匀的制件体积收缩率
华中科技大学硕士学位论文
注射ー压缩成型艺并不适川于制造任意形状的制件,对于不规则几何形状制件
的成梨,熔体在转角与变截面处流动受齪会引起积现象,致使压缩过屜中熔体不
1j区域纤维流线被不均匀的拉伸,影响制成件质量。所以注射-压缩工艺更适片丁制
造对称形状的制件。
关键词:注射一缩成槊;多物理场;数但模拟;维流长;收缩
华中科技大学硕士学位论文
Abstract
With the rapid development of polymer engineering, large transparent polymer parts
are widely used in automobile and aerospace industries, for example, the fabrication of car
glasses and large transparent aeroplane coverings. Due to their unique applications, they
should have good mechanical and optical qualities. However, how to design fit procedure
to produce such high-quality products is a great concern. Earlier research turned out that
when traditional injection molding is used to make such large transparent polymer parts,
nor-uniform distribution of pressure, temperature and fiber flow line on the product may
give rise to residual stress during the molding process and bring about unequal shrinkage
on different points of the product, especially edge and angle areas, after molding is done
as a result bring defects like warp and birefringence which will make negative impacts on
the mechanical and optical quality of the product. To solve the problem, an improved
Injectior-compression Molding (CM) is been noticed, especially on the aspects of
molding process analysis and parameter optimization
Compared with injection molding, ICM allows mold to move, adding a compression
stage at the end of the inject process. This extra work helps to control the variation
polymer temperature and pressure, and eliminate the problem of residual stress and
uneven shrinkage on root. As the late start on ICM in China, little information has been
obtained on ICM in areas Iike parameter variation, utility of ICM and noticing, which are
of great value to be used to design procedure for specific parts making
Using computer-based numerical simulation technique, base on nonlinear numerical
algorithm, this paper uses multi-physics calculation method to simulate ICM on plates
with different geometric structures thoroughly, and compared its results with ones done by
traditional injection molding. Following conclusions are obtained
There is a consistent pressure distribution in the mold when ICM is done. Beside