田口方法應用於反壓之氣體輔助射出成型的最佳化及模擬分析

Optimization and Simulation for Gas-Assisted Injection Molding with Counter Pressure by the Taguchi Method

吳鑑洲(Chien-Chou Wu)

指導教授 ： 鍾文仁

中原大學/工學院/機械工程研究所/博士(2017年)

https://doi.org/10.6840/cycu201700330

摘要

氣體輔助射出成型概念是在充填階段將氣體注入短射熔膠內，利用壓縮氣體作為推動熔膠與保壓的媒介，透過中空成型達到節省成本的目的，因此在成品品質上多針對穿透長度與掏空率作要求，本研究將氣體反壓機制應用至氣體輔助射出成型製程中，控制熔膠波前流動的行為，改變氣體的穿透長度及掏空率，並透過田口實驗方法以實驗及模擬分析兩種方式來探討因子水準對掏空率及穿透長度的影響，同時探討製程參數對機械強度之影響。
本研究之實驗成品採用迴紋針形狀之設計，進行具反壓機制之氣體輔助射出成型實驗，設定四個可變動參數之控制因子：反壓壓力、熔膠溫度、氣輔壓力及延遲時間，以L9直交表來進行實驗設計，依據各組之因子水準進行實驗，探討與比較各組之穿透長度及掏空率，並歸納出一組驗證組，經由驗證組的結果可以說明，在採用田口方法時，當單一組別之S/N比特別顯著時，可採用另一品質特性之S/N比來協助得到最佳因子水準組合之目標。
本研究在模擬分析軟體中建立與實驗成品相同之模型，依據上述實驗中各組之因子水準來設定，並進行模擬分析，探討與比較各組之穿透長度及掏空率，並將模擬結果與實驗結果做比對，比較兩者之差異，將實驗之驗證組進行模擬分析，結果顯示驗證組在穿透長度及掏空率之數據上均大於其他組別。
本研究並進一步對成品直線段部分做機械強度之測試，包含彎曲試驗及衝擊試驗，探討成型條件與機械強度彼此間之關係，發現近反壓口之彎曲強度及衝擊強度大於遠反壓口之彎曲強度及衝擊強度，將驗證實驗之成品進行彎曲試驗及衝擊試驗，此兩種試驗在驗證組之強度亦大於直交表中之各組，亦即當成品掏空率較大時，成品之密度會較大，相對的機械強度亦會較大。

關鍵字

氣體輔助射出成型 ； 田口方法 ； 氣體反壓 ； 穿透長度 ； 掏空率 ； 機械強度

並列摘要

Gas-assisted injection molding (GAIM) means that, during the filling stage, gas is injected into short-shot melt. Compressed gas is used as the packing medium to push the melt to form hollow sections and keep the sections from shrinking. This process significantly reduces material usage and costs. Therefore, in terms of the quality of molded parts, requirements are made based on penetration length and hollow percentage. This study applies a gas counter pressure (GCP) mechanism to GAIM in order to control the meltfront action of melt, change the penetration length and hollow percentage. The influence of factor level on the hollow percentage and penetration length was discussed by experiment and simulation analysis through the Taguchi Method.. The influence of process parameters on mechanical strength was also discussed.
The molded part of this study is designed into the paperclip-shaped, and GAIM with a GCP mechanism is adopted in the experiment. Four control factors: counter pressure, melt temperature, gas-assisted pressure, and delay time. This study employs the L9 Orthogonal Array to design an experiment, according to the factor level of each group, the penetration length and hollow percentage of each group were discussed and compared, and a set of verification groups was grouped. The results of the verification group could show that when using the Taguchi method, S/N ratio is particularly significant, the S/N ratio of another quality characteristic can be used to help achieve the goal of optimal factor level combination.
In this study, we establish the same model as the experimental product in the simulation software. According to the factor level of each group in the above experiment, the simulation results show that the penetration length and the hollow percentage of each group are discussed and compared. Compared with the experimental results, the difference between the two, the experimental verification group for simulation, the results show that the verification group in the penetration length and hollow percentage data are greater than other groups.
In this study, the mechanical strength of the part is further tested, including the bending test and the impact test. The relationship between the forming conditions and the mechanical strength is discussed. , It was found that the bending strength and impact strength of the near counter pressure were greater than the bending strength and impact strength of far counter pressure. The two tests in the verification group is also greater than the strength of other groups, that is, when the hollow percentage of product is larger, the density of the product will be larger, the relative mechanical strength will be larger

並列關鍵字

gas-assisted injection molding (GAIM) ； Taguchi Method ； gas counter pressure (GCP) ； penetration length ； hollow percentage

參考文獻

36. 科盛科技股份有限公司, 2007, “Moldex3D 模流分析技術與應用”, 全華科技圖書公司.

20. Kuo, J. K., Huang P. H., and Chang S. M., 2011, “Displacement Impact On PEM Fuel Cell Bipolar Plate For S316L Fiber Orientation and Cooling System,” Journal of the Chinese Society of Mechanical Engineers, 32(5), pp. 409-417.

1. Chen, S. C., Hsu, K. S. and Huang, J. S.,1995, “Experimental Study on Gas Penetration Characteristics in a Spiral Tube during Gas-Assisted Injection Molding,” Industrial & Engineering Chemistry Research, 34(1), pp.416-420.

2. Chen, S. C., Chien, R. D., Chen, Y. C. and Teng, M. Y.,2004. “Study of Mouldability in Gas-Assisted Injection Moulded Fibre-Reinforced Nylonparts,” Plastics Rubber and Composites, 33(2-3),pp. 113-119.

3. Chien, R. D., and Chen, S. C., 2004, “Investigations into Surface Visual Quality of Gas-Assisted Injection Moulded Polypropylene Parts,” Plastics Rubber and Composites, 33(4), pp.155-162.