Abstract: The quality problem of plastics part caused by difficulty in melt filling mold flow in molding parts with micro size or with local tiny structure was investigated. Sheet parts with micro cylindrical array structure were taken as the research object. For two kinds of polymer materials, high-density polyethylene (HDPE) and polypropylene (PP), the micro injection mold which integrated the technologies of vacuum exhaust and ultrasonic vibration was used to study the change of micro cylindrical fillet curvature radius with and without ultrasonic field and under the condition of varying process parameters and ultrasonic power. Without ultrasonic field, raising temperatures of melt and mold and increasing injection rate could decrease the fillet radius of curvature for the micro-column of the two polymer materials. While the fillet radius of curvature for the micro-column could further decrease with ultrasonic field, thereby improving the filling quality of parts. Meanwhile, no matter whether applying ultrasonic field or not, the fillet radius of curvature for the micro-column filled by HDPE polymer material was significantly smaller than that by PP polymer material.

Key words: microscale, polymer, molding, ultrasonic vibration, filling quality

摘要： 针对微小尺寸或局部带有微小结构的制件模塑成型时熔体充模流动困难而影响制件质量的问题,以典型的带有微圆柱阵列结构的薄板型制件为对象,提出将抽真空排气和超声振动技术集成应用到自行设计制造的微注塑模具中,并采用单因素成型实验方法,研究了高密度聚乙烯(HDPE)和聚丙烯(PP)两种聚合物材料在施加与不加超声外场以及不同工艺参数和超声功率变化条件下填充薄板型制件上微圆柱圆角曲率半径的变化规律.结果表明,不加超声外场时提高熔体和模具温度及增大注射速率可使两种材料填充的微圆柱圆角曲率半径逐渐减小,施加超声外场时填充的微圆柱圆角曲率半径可进一步减小,从而有效提高了制件的填充质量;同时发现,无论有无超声作用,HDPE材料填充的微圆柱圆角曲率半径均明显小于PP材料.

关键词: 微尺度, 聚合物, 模塑, 超声振动, 填充质量