Property-control in forging on screw presses by energy dosage and local actuators

闭模锻造的目标通常是在降低的成形力下成形工件，并利用在高同源温度下发生的微观结构变化来设定应用的性能。热成形过程中微观组织的演化可以看作是一个动力学系统。它是由工件中的材料点处的温度场和速度场的时间演化控制的。初始微观结构以及摩擦和传热条件的变化导致性能的变化。当在螺旋压力机上锻造时，工件通过几次打击成形。在这里，一般似乎可以控制在冲击过程中微观结构演变的动态系统。冲击能量和冲击之间的道次间时间的适应可用于补偿偏差，例如，相对于温度，由于工件的延迟运输。通常，在模锻过程中不可能特别影响关键工件区域。工具中缺乏自由度，使得不能以有针对性的方式局部引入成形能量。到目前为止，还没有已知的工作，其中使用的冲击能量专门作为控制变量，直接控制锻造过程中的组织和性能的形成。此外，没有对关键位置的局部影响是可能的，因为在锻造工具，超越了敲落功能的致动器是目前没有国家的最先进的。本项目建议书的主题是研究，实施和验证的观察员和闭环控制策略的全局和局部性能控制的能量结合锻造螺旋压力机。如果在工件的特定区域中指定目标微观结构，则可以使用静态优化方法计算最佳冲击序列作为参考。然后，在工艺过程中从测量的传感器值估计微结构的发展。第一个子目标是开发基于能量的材料模型，即，基于通过成形引入到微观结构中的能量，制定和验证用于确定性能的微观结构变量的材料方程。材料模型应与基于插值FEM解的在线过程模型相结合。在这里，一个运动方程的域的边界与满足微结构的要求是派生。该模型形成控制的基础，该控制将作为域边界的实际状态和目标状态之间的跟踪控制来实现。开发的解决方案首先使用FEM模型进行虚拟测试，然后转移到机械设计和制造的椅子的螺旋压力机。

Closed-die forging usually has the goal of shaping a workpiece at reduced forming forces and utilizing the microstructural changes occurring at high homologous temperatures to set the properties for the application. The evolution of the microstructure can be considered as a dynamic system during hot forming. It is controlled by the temporal evolution of the temperature and velocity fields at the material points in the workpiece. Variations in the initial microstructure and the friction and heat transfer conditions lead to variations in properties. When forging on screw presses, the workpiece is brought into shape with several blows. Here it generally seems possible to control the dynamic system of microstructure evolution over the course of the blows. Adaption of impact energy and interpass times between impacts could be used to compensate for deviations, e.g., with respect to temperature, due to a delayed transport of the workpiece. Usually, it is not possible to specifically influence critical workpiece areas during drop forging. There is a lack of degrees of freedom in the tools, so that forming energy cannot be locally introduced in a targeted manner. So far, no work is known which uses the impact energy specifically as a control variable to directly control the microstructure and property formation during forging. Also, no local impact on critical locations is possible because actuators in forging tools that go beyond the knock-off function are currently not state-of-the-art. The subject of this project proposal is the research, implementation and validation of observer and closed-loop control strategies for the global and local property control of energy-bonded forging on screw presses. If the target microstructure is specified in a specific area in the workpiece, an optimal impact sequence can be calculated as a reference using static optimization methods. The development of the microstructure is then estimated from measured sensor values during the course of the process. A first sub-goal is the development of an energy-based material model, i.e. the formulation and validation of material equations for the property-determining microstructural variables on the basis of the energy introduced into the microstructure by forming. The material model shall be combined with an online process model based on interpolated FEM solutions. Here, an equation of motion for the boundary of the domain with fulfilled microstructural requirement is to be derived. This model forms the basis for the control, which is to be implemented as a follow-up control between the actual state and the target state of the domain boundary. The developed solution is first tested virtually using an FEM model and then transferred to the screw press of the chair of mechanical design and manufacturing.