厚件產品保壓過程對於收縮率與殘留應力影響之研究

Study of the Influence of Packing Process on Shrinkage and Residual Stress in Thick Parts

林炫良(Hsuan-Liang Lin)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300394

摘要

本研究乃是針對厚件成品之成型品性質中的殘留應力及收縮方面作一研究與探討。在實驗中我們使用截面為長105mm，寬90mm的方形試片模具，其模具可改變成型品的厚度，分別針對不同三種厚度（4mm，6mm，8mm）、兩種不同材料（PMMA、PC）對其做改變不同保壓壓力及保壓時間兩種不同製程參數。並且利用實驗所得之實驗參數代入CAE分析軟體MPI模擬其成型情形，以驗證其軟體在這方面之準確性。
在探討收縮方面，我們可以發現隨著保壓壓力的增加，收縮的情形也隨著加以改善。由實驗中發現保壓壓力及保壓時間的增加時，成型品的重量值也會隨著上升。由實驗結果以及分析結果中皆可發現在相同的保壓條件下，厚度越大，其收縮率的值也就相對的變大。
在量測殘留應力方面，我們利用光彈量測系統照射其成型品來觀察成品不同厚度、材料及製程參數所成型之試片表面做量測，觀察其雙折射率差值在成型品之表面所形成的分佈狀況，進而判斷殘留應力的分佈。在實驗結果中，我們得到在不同厚度下，隨著保壓壓力的增加，殘留應力也隨之上升，但在不同材料中，又可知不論實驗或模擬分析，PMMA的成型品較PC的成型品之殘留應力小。

關鍵字

收縮 ； 保壓 ； 殘留應力 ； 厚件成品

並列摘要

The study concerns about the residual stress and shrinkage in injection molded thick parts. In the experiment, flat parts with 105 mm in length and 90 mm in width were injection molded. Part thickness were varied from 4 mm to 6 mm and to 8 mm. Different processing parameters including holding pressure and holding time were used. CAE analyses were also implemented to assist in the evaluation of residual stress and shrinkage formation.
The digital photo elasticity system is implemented to measure the residual stress and the associated distribution and to check how it varies with thickness and processing parameters.
For the thick parts, different processing parameters make a great effect. The residual stress show significant increases with increased holding pressure. And with thickness being greater, the shrinkage of thick part becomes greater. The result of CAE prediction shows qualitative trend with the observation of experiments.

並列關鍵字

thick parts ； shrinkage ； residual stress ； packing

參考文獻

1. Furong Gao, Xi Chen,” Setting of Injection Molding Packing Profile”, 2002.

2. Xi Chen, PhD Thesis, Hong Kong University of Science and Technology, 2002.

3. Xi Chen, F. Gao, “Influences of Packing Profiles on Part Quality”,Submitted to Polym. Eng & Sci, 2002.

5. Y. T. Koita, “Packing and Discharge in Injection Molding”, Polym. Eng. & Sci., Vol. 14, p.840-844, 1974.

7. K. Yoon and K. K. Wang, “The Effect of Holding Pressure on Frozen-in Birefringence in Injection Molding Disks”, S.P.E. Technical Paper, Vol. 38, p. 2221-2224, 1992.