Basic analysis and optimization of the flow behavior of thermoplastics by adjusting the surface of electrical discharge machined injection molds (EDSIMP)

通过调整放电加工注塑模具 (EDSIMP) 的表面对热塑性塑料的流动行为进行基本分析和优化

• 批准号: 447707042
• 负责人: Professor Dr.-Ing. Thomas Bergs
• 金额: --
• 依托单位: Institut für Kunststoffverarbeitung (IKV) in Industrie und Handwerk an der RWTH Aachen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/447707042?language=en
• 关键词: Basic; analysis; optimization; flow; behavior

Manufacturing of injection molds aims at functional surfaces being as smooth as possible in order to achieve uniform filling and maintaining low flow resistance at the same time. Studies in the field of fluid mechanics as well as preliminary experiments have shown that micro structured mold surfaces can reduce shear rate and flow resistance as well as enlarge flow path lengths.Basically, the reduction can have two consequences for injection molding: First, faster filling times for constant injection pressures can help reducing the cycle time of injection molding. Faster injection speeds can further lead to improved achievable flow lengths due to less cooling as well as a more homogeneous temperature distribution within the cavity, which improves the quality of the part. Second, decreased pressure loss over the flow path could reduce the amount of required gates and furthermore, for constant injection velocities, it could help to reduce shear of plastic melt and therefore thermal stress. Another direct advantage of lower injection pressure is the reduction of the required clamping force, which also decreases the energy consumption in the injection molding process and can enable the use of smaller injection molding machines. The reliability of the injection molding process can furthermore be increased due to less downtime because of maintenance of the injection mold caused by mechanical load and pressures. In addition, fundamental knowledge on the influence of microstructured mold surfaces on the plastic flow behavior can help to deterministically optimize the process in future.In this project, the influence of the electrical discharge machined (EDM) mold surfaces on the flow behavior of thermoplastic materials will be comprehensively analyzed. EDM is a frequently used process for mold manufacturing and allows for detailed tailoring of surfaces. As a first step, the discharge energy dependent structures of sinking EDM will be experimentally investigated in terms of different roughness regimes which are inherently connected to an according extend of a thermally altered rim zone during mold manufacture. For modelling and simulation of surface structures and the validation of their influence on plastics flow, the impact of the EDM surface integrity on the heat transfer coefficient (HTC) at the molds wall will be in experimental and simulation focus. This represents the distinct research point of WZL. In addition, the durability of created mold surfaces will be monitored by long term testing (WZL and IKV). The further investigations will be based on the coupling of Computational Fluid Dynamics (CFD) with heat transfer coefficient (HTC) simulations as function of the surface structure along with validation experiments and measurements during injection molding, representing the core research of IKV.

注射模具的制造目标是尽可能光滑的功能表面，以实现均匀的填充并同时保持低流动阻力。在流体力学领域以及初步实验中的研究表明，微结构型霉菌表面可以降低剪切速率和抗流抗性以及扩大流动路径长度。基本上，减少可以对注射成型产生两个后果：首先，恒定的填充时间可以帮助减少注射型成型的周期。更快的注入速度可以进一步导致由于较少冷却以及腔内更均匀的温度分布而改善可实现的流量长度，从而提高了零件的质量。其次，流动路径上的压力损失降低可以减少所需的门的量，此外，对于恒定的注入速度，它可以帮助减少塑料熔体的剪切速度，从而减少热应力。较低注入压力的另一个直接优势是减少所需的夹紧力，这也减少了注入成型过程中的能量消耗，并可以实现较小的注射模制机。由于维持机械负载和压力引起的注射霉菌的维持，注射成型过程的可靠性可能会增加。此外，对微结构模具表面对塑性流动行为的影响的基本知识可以帮助确定将来的过程。在本项目中，将全面分析电气放电加工（EDM）模具表面对热塑性材料流动行为的影响。 EDM是用于模具制造的经常使用的过程，可以详细剪裁表面。作为第一步，下沉EDM的排放能量依赖性结构将以不同的粗糙度状态进行实验研究，这些粗糙度状态固有地与模具制造过程中的热改变的边缘区相连。为了建模和模拟表面结构及其对塑料流的影响的验证，EDM表面完整性对传热系数（HTC）在模具壁上的影响将是实验和模拟焦点。这代表了WZL的独特研究点。此外，将通过长期测试（WZL和IKV）监视创建的模具表面的耐用性。进一步的研究将基于计算流体动力学（CFD）与传热系数（HTC）模拟作为表面结构的函数以及注射成型过程中的验证实验和测量的耦合，代表IKV的核心研究。