Development of the skin layer in injection moulding: phenomenological model
Development of the skin layer in injection moulding: phenomenological model
复制标题
DOI：
10.1016/j.polymer.2003.12.001
复制
发表时间：
2004-02
期刊：
影响因子：
4.6
通讯作者：
J. Viana
中科院分区：
文献类型：
--
作者：
J. Viana
这项工作探讨了影响注射成型中皮层发展的条件。的热机械环境是不同的系统的变化的操作工艺参数为三个成型几何形状：一个轴对称的拉伸杆，一个横向浇口盘和一个两点的中央浇口盒。的热机械环境进行了评估，通过计算机模拟，由当地的整体温度和剪切应力水平。无量纲数的计算（卡梅隆，Brinkman和Nahme）允许的主要物理现象发生在不同的造型几何形状的解释。建立了所施加的热机械环境与表层厚度之间的关系。对于所有的模塑件，表皮厚度随着热应力和剪切应力水平的增加而减小，尽管对于不同的模塑件几何形状具有不同的贡献。皮层的发展被解释在光的现象学模型涉及两个时间变量：允许的时间松弛的高度取向的熔体，直到达到结晶温度和松弛时间的材料。讨论了操作工艺参数对两个时间变量的影响，并用来解释皮层厚度的实验变化。
This work explores the conditions affecting the development of the skin layer in injection moulding. The thermomechanical environment is varied by systematic changes on the operative processing parameters for three moulding geometries: an axi-symmetric tensile bar, a lateral gated disc and a two-point central gated box. The thermomechanical environments are evaluated by computer simulations, by the local bulk temperature and shear stress level. The calculation of dimensionless numbers (Cameron, Brinkman and Nahme) allows the interpretation of the main physical phenomena occurring in the distinct moulding geometries. The relationships between the imposed thermomechanical environment and the thickness of the skin layer are established. For all the mouldings the skin thickness decreases with the increase in the thermal and shear stress levels, although with distinct contributions for the different moulding geometries. The development of the skin layer is interpreted in the light of a phenomenological model involving two time variables: the time allowed for relaxation of the highly oriented melt until the crystallization temperature is reached and the relaxation time of the material. The influence of the operative processing parameters on both time variables are discussed and used to interpret the experimental variations of the thickness of skin layer.