the part at Gate 4 induces flow stresses that are above the
degradation level of polypropylene along the bottom edge of
the PORT HOUSING. This, however, is not serious enough
to rule out this gating option. Although Gate 2 leads to the
lowest flow stresses in the part among the four gate locations
studied, this gating option is prone to excessive short shots
during start-up and causes core pins to break. Based on the
design, the optimum gate location for the minimum flow
stresses and uniform fill pattern appears to be Gate 3.
Design 2, with wall thicknesses in the NEEDLE HOUSING
increased by 0.125 mm, reduces the flow stresses, thus,
decreasing the possibility of bowing. The flow stresses also
significantly increases throughout the part while injecting
the polymer at a lower melt temperature of 220 o
C and
longer injection time of 1.2 second.
In order to minimize the flow stresses in the part combined
with the preference not to gate at Gate 2, it is recommended
to gate at Gate 3. For the minimization of the possibility of
the part bowing, it is suggested to process at higher melt
temperatures and design the mold to accommodate an
increased wall thickness of the part if necessary.
Cavity filling analysis, using computer-aided engineering
(CAE), was employed to analyze process parameters and
gate location in the replication of the part. It is shown to
design process parameters and mold for the cost-effective
mass production of a needle cover.
Acknowledgments
The authors would like to thank Korea Textile Machinery
Research Institute (KOTMI) for the support of Computer-
Aided Engineering.
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s ç
Table 1. The cavity filling analysis results with four different gate
4 37.2 241 226
*Numbers in parentheses indicate values for Design 2, material=
polypropylene, mold temperature=30 o
C, melt temperature=240 o
C,
injection time=0.6 second.
Four different gating options were investigated as shown in
Figure 1. The CAE model was constructed using shell
*Corresponding author: dhchun@ynu.ac.kr Figure 1. Finite element model and terminology of a needle cover.摘要：对于具有成本效益的大规模生产的塑料零件，注射成型是最常用的一种制造方法。对熔融聚合物的充分分析提供了有用的信息来调查能确保成功复制的工艺条件。为了确定针盖合适的浇口位置，对流动前沿和流动应力的四种不同的控制选项和三种不同的设计方案进行了分析和比较，得出最后的结果。基于所述结果，最小流动应力和均匀的填充模式的浇口位置似乎是浇口方案3。因此，它也提供了最低限度的整个PORT住房和针管壳体零件翘曲的可能性。壁厚增加，较低的熔融温度和较长的注射时间上的分析结果表明，较高的熔体温度更有利于成功成型。注入聚合物的时间较长（1.2秒），会导致整个系统的流动压力显著增加和壁厚的增加，以便于成功实现零件的模塑成型。 针盖的注塑模具分析英文文献和翻译(4):http://www.751com.cn/fanyi/lunwen_758.html