在產品開發多元化的時代中,氣體輔助射出成型的技術一直扮演重要的角色,尤其對於厚實及長而薄的塑膠產品,均可以大幅改善在傳統射出所產生的肉厚限制及翹曲問題,不但拓展產品開發的範圍,亦可降低射出成形機的負擔。 本研究中,針對全射式氣體輔助成型技術運用在65吋電漿電視前殼的開發過程中,所產生的成品表面的縮水、顏色差異、翹曲變形以及產品尺寸作為研究主題,以瞭解成品所產生的品質問題,並利用製程參數條件設計進行實驗,依序對縮水、顏色差異、翹曲變形及尺寸的變異進行研究。由實驗的結果得知,低料溫對產品品質在表面凹痕、色差方面具有改善的正面效果,由其是在190~210℃之間。另外,若模溫設定在60~80℃之間可以降低顏色的差異;而在氣體延遲時間、氣體充填時間及氣體壓力的方面,對於縮水與色差的情況,卻呈現不同趨勢。氣體延遲時間越長,縮水情況更加嚴重,卻可以降低色差;氣體充填時間越長,縮水得以改善,色差值卻微幅的增加;氣體壓力越大時,可以改善縮水,卻增加了色差;在翹曲變形的部份,在實驗的條件中取得26組的有效參數,呈現出翹曲量對成型視窗影響很小;而在尺寸的部份,隨著熔膠溫度、氣體延遲時間的降低,以及氣體充填時間、氣體壓力的增加,可以使尺寸稍微的增加。 上述成型條件的改變得到氣體掏空與皮層厚度是影響品質的關鍵因素,並間接影響到穿透長度及後續之各項品質。
The Gas-Assisted Injection Molding plays an important role in the molding technology. It could improve the sink mark and warpage of the Conventional Injection Molding, especially the thick or long-thin plastic product. In this study, used the Gas Assistance Injection Molding (Full-Shot) to mold the front cover of 65 inch PDP TV, and focused on the product process influence of the sink mark, color difference in surface, warpage and size. To design the experiment parameters and study the influences of different process parameters. The experiment results show that the lower melt temperature has a significant effect on the product quality in the sink mark and color difference, especially when it is between 190℃ and 210℃. In addition, the color difference can be reduced when the mold temperature is between 60℃ and 80℃. The gas fill time and the gas pressure, it appears different trend between sink mark and the color difference. The longer gas delay time, the worse situation of sink mark, but the less difference in color. The longer gas fill time, the better situation of sink mark, but the higher color difference. When the gas pressure is higher than 120 Bar, sink mark can be improved but the color difference becomes worse. The experiment results also show that the lower melt temperature, shorter gas delay time, longer gas fill time and higher gas pressure can increase the dimension accuracy slightly. The gas penetration length and skin thickness that changed the foregoing process parameters are key factors affected product quality, and have an indirect effect on all quality issues. Keywords:Gas-Assisted Injection Molding; Gas penetration.