Study on The Effect of Gas Counter Pressure on Molded Qualities in Gas-assisted Molding Injecting Process

• Main Authors: Tao-Hsiang Tang, 湯道祥
• Other Authors: Wen-Ren Jong
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/19220631356152034033

碩士 === 中原大學 === 機械工程研究所 === 101 === Gas-assisted injection molding technology is a part of energy-saving injection technology in plastic injection field . Besides saving material using to make the lightweight part , but also shorten the molding and cooling cycle time to achieve the purpose of energy saving and carbon reduction . However , gas-assisted injection applications is still in its uneven material thickness and other shortcomings and lack of penetration , its make the uneven shrinkage on finish part and impact the appearance . And gas counter pressure method is used in many forming injection molding to control the bubble size and direction to improve the quality of forming injection molding part . If their application in gas-assisted injection molding , when the melt flow from thin position to thick position , it’s can be obtained a more average thickness material due to the gas counter pressure , this phenomenon is called corner effect . This follow-up experiments confirmed through gas counter pressure mechanism for gas-assisted injection molding of product quality improvement . The results show that in the molding shrinkage of gas counter pressure applied to gas-assisted injection molding process , the higher the gas counter pressure , shrinkage tended to decrease . When the gas pressure in the 0、40、80、120 bar , the part shrinkage rate in the longitudinal direction and width were 0.41％、0.37％、0.34％、0.32％與0.54％、0.45％、0.43％、0.39％ . In part corner effect , when the gas counter is higher , the average height hollowed upward trend , the measure result relative to 0 bar gas counter pressure , when gas counter pressure at 40、80、120 bar , the part hollowed height increased by 0.51％、0.55％、1.18％ .