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Based on above assumptions and heat transfer
principles, the mathematical model of the temperature field is
expressed by Fourier differential equation of heat transfer as:
Where, K is the heat transfer coefficient of the melt,
W/(m o
C); T is the transient temperature of the melt (
o
C); t is
the time, is the density of the melt (kg/m3
); C is the specific
heat of the melt at constant pressure (J/kg o
C); x, y, z are
values on coordinate axes (m).
V. INTEGRATION OF HOT-RUNNER DESIGN AND ANALYSIS
INFORMATION
=+ + +
where, P is the injection pressure (MPa); is the internal
pressure (MPa); R’ is the modified gas constant [N·cm/(g/k)];
T is the absolute temperature (K); is the volumetric mass of
the fluid at absolute zero point.
Runner diameter is calculated as:
22(31)/ ss ss
dR nQnπγ == +
where, n is a non Newtonian index (/sec); Qs is the
volumetric velocity of the melt in the main runner(cm3
/sec) ;
s is the shearing velocity of the plastic melt in the main
runner, and it is 5x103
/sec.
Usually, gate diameter of a hot-runner mold is between
0.55 and 0.7mm. Similar to other gates of plastic injection
molds, the bigger the diameter is, the better the resin can flow
but larger remainder. Therefore, before deciding the gate size,
a comprehensive analysis about weight, structure, and surface
technical requirement of the product is necessary. Resin
properties and mold structure need to be considered as well.
Usually, for the same product, the size of a hot-runner gate is
smaller than that of a pin gate. Here are the rules of shape,
position and dimension design of a gate:
Rule1. IF product feature = [thin wall (shell, box)],
THEN gate shape = [round]
Rule2. IF product feature = [wall],
THEN gate position = [center or corners of the wall, or edge
midpoints of the wall]
Rule3. IF product feature = [protrusion],
THEN gate position[point on the protrusion]
IF product feature = [reinforcing rib],
THEN gate position[point on the reinforcing rib]
Rule4. IF plastic flowability = [good],
THEN gate dimension = [less than the estimation]摘要：本文分析了当前塑料注射模热流道设计，并介绍了一个概念信息的知识表示方法和单位（KU）结构单元（SU）建立一个知识库（KB）。然后设计了一种多型腔模具的热流道结构基于知识驱动机制，并进行了仿真分析和优化设计。因此，基于知识转移，实现了多型腔注射模热流道设计的信息集成。
指数条款-热流道 知识 多型腔注射模设计 集成
一、引言
较短的生产周期时间优势，原材料消耗，减少废物的产品，提高产品质量和应用范围的扩大，塑料注射成型，热流道是在第十一个五年计划的一个关键技术。
在热流道产品开发领域，许多公司的技术进行了研究，例如：加拿大的MOLD- MASTERS，美国的HUSKY, INCOE, DME, HASCO, FASTHEAT，德国的EWIKON, GUNTHER，英国的PLASTHING，意大利的THERMOPLY，日本的SEIKI，韩国的YUDO。这些公司已经进行了研究和开发的热流道技术，已成功应用于塑料注射成型制品。在理论研究方面，R.Spina通过各系统的可行性，并用有限元分析研究比较了不同的热流道系统，门和产品配置，评价制造过程的热应力和应变分布。L.Kong, J.Y.H.Fuh建立了一个三文塑料注射模具设计系统，在该模具结构的设计中可以用一个软件开发形成三文CAD环境。Ko-Ta Chiang等人提出了一个方法通过灰色模糊逻辑分析来有效地优化加工参数对薄壁注塑件的影响。在建立随机多项式矩阵模型方面，陆赤煌等人已经通过建立随机多项式矩阵的模型，开发了相应的热电偶表示系统。苏娟华等人研究和讨论了设计过程和具体的注塑热流道模具的设计方法。张卫中等人研究的是了热流道系统的一个喷嘴部分，然后做了详细的设计与CAE分析它。这些研究从不同的角度极大地推动了塑料注射模热流道设计。然而，设计工作涉及有关的材料，结构，力学和加工的复杂知识，因此，对结构设计过程的集成，解决相应的表达式，以及温度场的仿真分析是必需的。缺乏知识支持或只注重单方面的研究，一个完整的设计很难做。多腔模具和腔的结构设计应根据产品的数量和规格设计而不能因为个人设计导致可重用性缺乏和低效率。