共查询到18条相似文献,搜索用时 265 毫秒
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聚碳酸酯(PC)注塑制品出模后在无外加约束条件下内部应力得不到松弛释放,易导致制品产生开裂,严重影响制品的服役性能。为探究PC制品内应力分布规律,找到有效降低内应力的工艺措施,基于气体辅助注射成型(GAIM)工艺和自行设计制造的带有半圆形加强筋的平板试验模具,结合光弹法和溶剂检测法,研究GAIM制品内应力的分布特点,讨论注气压力和气体保压压力两种工艺参数对GAIM制品内应力的影响规律,提出两种改善制品内应力的工艺方法。研究发现:通过光弹法观测到的应力条纹分布与溶剂浸泡后的裂纹开裂区域一致,即GAIM制品末端及边缘处内应力较大,沿气道两侧应力分布较均匀;较高的注气压力和较低的气体保压压力可以更加有效减小GAIM制品的内应力;通过对GAIM制品24 h即时退火和延长二次注气的卸压时间可以有效降低制品内应力。 相似文献
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《塑料工业》2016,(4)
基于自行构建的流体辅助注塑实验平台,对5种不同截面型腔管件的溢流法气体辅助注塑(GAIM)和水辅助注塑(WAIM)进行了实验研究。研究了辅助介质对管件流体穿透截面形状、残余壁厚大小和流体穿透率的影响规律以及工艺参数对流体穿透率的影响规律,并分析了其影响机理。实验发现:气体的穿透截面趋于型腔截面形状,水的穿透截面趋于圆形;GAIM的五截面管件的最小残余壁厚均大于WAIM,最大残余壁厚均随着内切圆圆心到壁面的最大距离的减小而减小;气体的穿透率较水的穿透率小,均随着圆率的增加而增加,随气体/水注射压力的增加而增加,随气体/水注射延迟时间的增加而减小,随熔体注射温度的增加而有所增加。这些发现为GAIM和WAIM制品截面设计及工艺参数调节提供了参考。 相似文献
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Bin Yang Mengya Ding You Shi Lei Hu Ru Xia Ji-Bin Miao Ming Cao Jia-Sheng Qian Peng Chen Yu-Chuan Zhang En-Fa Fu 《应用聚合物科学杂志》2019,136(16):47390
An umbrella handle product of polypropylene molded by gas-assisted injection molding (GAIM) was studied from both aspects: theoretical modeling and simulation as well as in situ temperature measurement. The simulation was primarily through the use of the commercial software Moldflow (version 6.1) coupled with enthalpy transformation method (ETM) in an attempt to investigate the shear rate and temperature fields during GAIM process. A four-parameter model (FPM) was used to nonlinearly fit the temperature decays during the GAIM cooling stage on the basis of a three-parameter model (TPM) raised previously in our group. The FPM showed perfect fitting effect as well as presented fairly acceptable cooling time (tc) prediction in comparison to experimental data, which could better reflect the nature of crystalline polymers during melt crystallization process. The understanding of the shear rate and temperature fields would be of practical importance to the further research on relationship of “processing–structure–property” as well as the optimization of cooling parameters for industrial GAIM operations of crystalline polymers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47390. 相似文献
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Shiu‐Wu Chau 《Polymer Engineering and Science》2008,48(9):1801-1814
This article proposes a generalized Newtonian model to predict the three‐dimensional gas penetration phenomenon in the GAIM process, where the gas and melt compressibility are both taken into account and hence the primary and secondary penetrations in GAIM processes are able to be quantitatively predicted. Additionally, an incompressible model requiring no outflow boundary is also presented to emphasis the influence of gas compressibility on the primary penetration. Based on a finite volume discretization, the proposed numerical model solves the complete momentum equation with two front transport equations, which are employed to track the gas/melt and air/melt interfaces. The modified Cross‐WLF model is adopted to describe the melt rheological behavior. The two‐domain modified Tait equation is exploited to represent the melt compressibility, while a polytropic model is employed to express the gas compressibility. The proposed schemes are quantitatively validated by the gas penetration characteristics in a clip‐shaped square tube, where good prediction accuracy is obtained. The influences of five major molding parameters, such as the injection pressure, mold temperature, melt temperature, delay time, and melt material on the gas penetration characteristics in the same clip‐shaped square tube via the proposed numerical approach are extensively presented and discussed. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
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详细介绍了气体辅助注射成型的物理过程及其关键工艺参数对成型的影响。以带加强筋的绣花机外壳为例,考察了传统注射成型与气体辅助注射成型的优缺点。针对气体辅助注射引入的新工艺参数,介绍了一种CAE技术与统计学的Taguchi正交实验相结合的方法,设计L9(34)正交实验表在可成型范围内寻求最优工艺参数。结果表明,气体辅助技术能减少原料,对有加强筋的制件能有效地去除沉降斑、减弱不均匀收缩及减少内应力,大大改善制件的表面质量,增强制件尺寸的稳定性。 相似文献