薄壁带筋轮座注射成型表面料花缺陷形成机理与改善

Formation Mechanism and Improvement of Bloom Defect on Surface of Thin-walled Wheel Seat with Reinforcement during Injection Molding Process

以薄壁带筋轮座件为研究对象,针对其在注射成型过程中表面易产生料花缺陷的问题,基于Moldflow软件对熔体流动规律和料花形成机理进行了研究,并利用金相观测方法对表面料花缺陷处的微观形貌进行了分析。结果表明:在注射成形过程中熔体内存在气体导致料花的形成,模具排气结构对料花缺陷的形成有很大的影响。结合模具和产品结构的特点,提出增加前模镶件侧面的排气槽、加深前模镶件排气槽深度和改变进胶点位置等解决方案。结果表明,增加排气槽深度和排气槽数量,可使熔体里包裹的气体有效排出;采用三板模结构并将进胶位置从零件侧面底部提高到零件顶部后,可减少熔体在型腔中的转向次数,使得气体更易排出。

Taking the thin-walled wheel seat with reinforcement as the studying object, aiming at the bloom defects occurred on the surface of the plastic product during injection molding process, the melting flow law and the formation mechanism of bloom defect were researched based on the Moldflow software, and the microscopic morphology of the bloom defect were analyzed based on metallographic observation method. The results show that the formation of the bloom defect is mainly caused by the wrapping of the gas in the melting material, and the exhaust structure of mold has great influence on the formation of the bloom defect. Combining with the structure characteristics of the mold and the product, the solutions, such as increasing the exhaust groove on the side of the front die insert, deepening the depth of the exhaust groove on the front die insert, and changing the position of the glue injection point, are proposed. The results show that the gas wrapped in the melting material can be effectively discharged after deepening the depth of the exhaust groove of the front mold insert, and adding the numbers of the exhaust groove on the side of the front mold insert, the turning numbers of melting material in the mold cavity can be reduced effectively and the wrapped gas can be discharged more easily by adopting the three-plate mold structure and raising the glue feeding position from the bottom of the side to the top of the injection product.