Efficient Numerical Methods for Tool Optimization in Cold Forging

轻量化设计和制造技术中的资源效率要求使用高强度材料和复杂的几何形状，以实现等效的部件功能，同时减轻其重量。这对成形工具提出了巨大的挑战，并使其设计在刀具耐用性和零件精度方面变得复杂。因此，使用数值方法进行刀具设计是必不可少的。在这种情况下，通常的方法是计算孤立几何元件对刀具载荷和零件几何形状的影响，然后通过迭代过程执行手动刀具优化。虽然该过程可以改善单个方面，但无法基于该策略实现全局工具优化。一般来说，全局最优可以用数学算法来计算。然而，它们用于优化成形工具有两个缺点。首先，目前对刀具载荷的计算几乎全部采用有限元法进行。该方法对刀具/工件相互作用的整体计算要求较高的计算量。由于大量的迭代步骤，这使得优化过程效率低下。其次，由于计算时间有限，通常忽略了机床刚度对刀具载荷的影响。因此，优化过程的输入信息已经包含了显著的不准确性。为了消除这些缺点，在应用项目的背景下，将开发新的高效仿真工具和基于过程中实际刀具负载的整体系统的刀具优化方法。因此，该项目的目标，即通过智能、数字、迭代的工具设计，显著提高冷锻工具的耐用性和零件的精度，将得到实现。实质性的新颖之处在于通过弹性建模开发了有效的耦合方法来计算工具载荷，同时考虑了过程/机器相互作用，以及由弹性工具应变引起的部件偏差的数值补偿。通过将新开发的计算方法集成到刀具自动优化方法中，可以实现优化刀具几何形状的省时计算，尽管迭代步骤较多。为了达到这一目标，并开发建设性的跨学科方法，来自制造工程、数值和应用数学的科学家将在整个研究期间密切合作。

Lightweight design and resource efficiency in manufacturing technology require the use of high-strength materials and complex geometries in order to achieve equivalent part functionality, while reducing its weight. This poses a big challenge for forming tools and complicates their design with regard to tool durability and part precision. Therefore the use of numerical methods for tool design is essential. In this context the usual approach is to calculate the influence of isolated geometric elements on tool loads and part geometry and afterwards perform a manual tool optimization by means of an iterative process. While this procedure may improve single aspects, one cannot achieve a global tool optimization based on this strategy.In general a global optimum can be computed by means of mathematical algorithms. Nevertheless, their use for the optimization of forming tools features two weak points. Firstly, nowadays the computation of tool loads is almost exclusively performed by means of the Finite Element Method (FEM). This method requires high computational effort for a holistic computation of tool/ workpiece-interactions. Due to the large number of iteration steps this renders the optimization process inefficient. Secondly, due to limited computing time one often omits the influence of machine stiffness on tool loads. Therefore, the input information for the optimization process already contains significant inaccuracies.In order to remove these shortcomings, in the context of the applied project new efficient simulation tools and a holistic, systematic approach for tool optimization, based on the actual tool loads during process, will be developed. Thereby the goal of this project, namely a significant increase in durability of cold forging tools and in the precision of the parts by means of intelligent, numerical, iterative tool design, will be achieved. The substantial novelty is the development of efficient coupled methods for the computation of tool loads by means of elastic modeling, while accounting for process/machine-interactions, as well as the numerical compensation of component deviations caused by elastic tool strains. By integration of the newly developed computing methods into a methodology for automated tool optimization, a time-efficient computation of the optimized tool geometry can be realized despite the large number of iteration steps. In order to reach this goal and to develop constructive interdisciplinary approaches scientists from manufacturing engineering, numerics and applied mathematics will closely work together for the whole research period.