高深宽比微结构零件的无螺杆超声微注射成型充填机理与结构形态研究

High aspect ratio micro structured parts are important components for Micro Electronic Mechanical System (MEMS), which are widely used in the fields of microstrucuture measurement and microelectronic packaging. With the capability of molding part with complex structure and precise dimensions in a single shot, micro injection molding is considered to have great potential for the development in batch manufacturing of high aspect ratio micro structured parts. However, due to the machining difficulties of small size screw and the influence of the micro scale effect, micro injection molding still faces the challenges such as serious materials waste and micro cavities filling. The new method of screwless ultrasonic micro injection molding is expected to solve the above mentioned problems in a targeted manner because of its advantages in materials and energy saving and better molding performance of the plasticized polymer melt. On the basis of the research on the principle of screwless ultrasonic plasticizing, this project proposal focuses on the filling process of the micro injection molding after ultrasonic plasticizing. The micro-scale rheological properties and filling behavior of polymer melt under the coupling of ultrasonic field, the structural morphology of the molded part and the development and application of the molding system will be studied to reveal the dynamic response mechanism of micro-scale rheological behavior of the polymer melt, to determine the distribution law of the filling flow field and to elucidate the structural evolution mechanism of the molded part. The project results are supposed to be of great significance for enriching the batch manufacturing theory for high aspect ratio micro structured parts and guiding the process development of screwless ultrasonic micro injection molding.

高深宽比微结构零件是微机电系统中的重要元件，在微结构测量、微电子封装等领域应用广泛。微注射成型技术可一次成型结构复杂、尺寸精确的零件，在实现高深宽比微结构零件的批量化制造方面具有较大的发展潜力。然而，由于小尺寸螺杆加工困难和微尺度效应的影响，微注射成型技术还面临材料浪费严重和微结构充填困难等挑战。无螺杆超声微注射成型新方法兼具节能省材和塑化熔体成型性能较好的优点，有望针对性的解决上述难题。本项目在无螺杆超声塑化原理研究的基础上，进一步探索无螺杆超声微注射成型的充填过程，开展超声场耦合作用下高聚物熔体的微尺度流变特性与充填行为、成型零件的结构形态和成型系统的开发与应用研究，旨在揭示超声场耦合作用下高聚物熔体的微尺度流变响应机理，探明充填流场的分布规律，阐明成型零件的结构形态演变机制。本项目成果对于丰富高深宽比微结构零件的批量化制造理论，指导无螺杆超声微注射成型工艺具有重要意义。

高深宽比微结构零件是微机电系统中的重要元件，在微结构测量、生化传感等领域应用广泛。然而，由于小尺寸螺杆加工困难和微尺度效应的影响，高深宽比微结构注塑成型面临材料浪费严重和微结构充填困难等挑战。本项目提出一种基于超声塑化微注塑的高深宽比微结构零件成型新方法，针对超声塑化机理、熔体微尺度流变响应关键科学问题，通过基础实验、仿真模拟、成型试验和测试表征等方法，开展了超声塑化生热机理、熔体微尺度流变特性与充填行为、超声塑化微注塑成型装备研制和典型零件成型研究。主要成果如下：. 阐释了超声塑化生热过程的聚合物分子运动和能量转化机制。建立了基于联合原子的分子动力学模型和高速红外摄像生热实验系统，揭示了超声塑化系统同质与异质界面摩擦、高频锤击瞬态粘弹生热机理。. 提出了一种基于矩形狭缝型腔的微尺度流变测试新方法。搭建了一套型腔厚度可调、设有熔体储存区的稳态在线流变测试平台，建立了考虑非等温效应影响的Cross-WLF粘度模型，将模流分析软件的预测精度调高了30%以上。. 获得了一套超声塑化微注塑过程参数表征和结构形态调控技术。提出了一种表征“边塑化边注射”过程充填速率的新方法，探明了工艺参数对充填速率和制品结构性能的影响规律，实现了充填速率和制品性能的协同优化。. 研制了新一代全电动超声塑化微注塑成型原型装备。构建了成套超声塑化微注塑工艺过程控制系统，包括一套含3个谐振频率的超声振动控制与数据采集、柱塞和锁模机构运动控制等功能模块。实现了高深宽比微针阵列结构的高质量成型。. 发表学术论文18篇，其中SCI收录16篇（JCR一区15篇，含中科院一区2篇），中国卓越计划期刊收录2篇。授权国家发明专利7项。组织国内外学术交流论坛2次。培养优秀青年学者2人，其中晋升教授并获“湖湘青年英才”荣誉称号1人，晋升副教授1人。培养博士、硕士研究生13人。