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.

注塑模具制造的目的是使功能表面尽可能光滑，以实现均匀的充填，同时保持低流动阻力。流体力学领域的研究和初步实验表明，微结构模具表面可以降低剪切速率和流动阻力，并扩大流动路径长度。从根本上说，这种减少对注射成型有两个后果：第一，恒定注射压力的较快充填时间有助于缩短注射成型的周期时间。更快的注射速度可以进一步改善可实现的流动长度，因为冷却更少，型腔内的温度分布更均匀，从而提高了零件的质量。其次，流道上压力损失的减少可以减少所需浇口的数量，此外，对于恒定的注射速度，它可以帮助减少塑料熔体的剪切，从而减少热应力。降低注塑压力的另一个直接好处是减少了所需的合模力，这也降低了注塑成型过程中的能源消耗，并可以使用较小的注塑机。由于机械负荷和压力引起的注塑模具维护减少了停机时间，因此可以进一步提高注塑工艺的可靠性。此外，有关微结构模具表面对塑料流动行为影响的基础知识有助于在未来确定优化工艺。在本项目中，将全面分析电火花加工模具表面对热塑性材料流动行为的影响。电火花加工是模具制造中经常使用的一种工艺，允许对曲面进行详细的裁剪。作为第一步，将根据不同的粗糙度区域对下沉电火花加工的放电能量依赖结构进行实验研究，这些粗糙度区域与模具制造过程中热变化的轮缘区的相应范围内在地联系在一起。为了建模和模拟表面结构及其对塑料流动的影响，电火花加工表面完整性对模具壁处换热系数(HTC)的影响将是实验和模拟的重点。这代表了WZL鲜明的研究重点。此外，创建的模具表面的耐久性将通过长期测试(WZL和IKV)进行监控。进一步的研究将基于计算流体动力学(CFD)和传热系数(HTC)模拟作为表面结构的函数，以及注塑成型过程中的验证实验和测量，这是IKV的核心研究。