Simulation of Thermomechanically Caused Workpiece Deformations for the NC Milling Process

在数控铣削的粗加工过程中，由于切屑形成过程中的能量转换，大量的热量被引入到工件中。这进而导致了工件的整体热机械变形。这些变形在随后的精加工过程中仍然存在，因此可能导致冷却后的工件表面严重偏离其设计形状。因此，可能会超出关键的制造公差。该项目的一个方面是对由铣削过程引入的热机械变形进行补偿。这将通过使用和推广前两个项目阶段开发的混合模拟系统来实现。为了支持多个模拟序列，需要减少单个模拟所需的总体计算时间。为此，必须增强仿真系统，以允许针对流程状态和要求进行自适应的详细程度的仿真。为了能够更准确地表示工件轮廓，必须扩展虚拟区域方法以考虑高阶边界描述。要通过模拟和实验研究的另一个方面是通过比较不同的工艺参数值和不同的铣削策略来避免热引入到工件中。根据优先计划的总体目标，本项目的目的是开发和验证一种方法，该方法通过避免热引入和补偿不可避免的热机械变形，计算出将在完工零件中产生设计形状并保持在指定制造公差内的NC路径。

In the roughing process of NC milling, a significant amount of heat is introduced into the workpiece due to energy conversion during the chip formation process. This in turn leads to global thermo-mechanical deformations of the workpiece. These deformations remain present in the subsequent finishing process and may consequently cause strong deviations of the workpiece surface from its designed shape after cooling. As a result, critical fabrication tolerances may be exceeded.One aspect of this project is the compensation of the thermo-mechanical deformations introduced by the milling process. This is to be achieved through the use and extension of the hybrid simulation system developed in the previous two project phases. In order to enable multiple simulation series, the overall computation time required for a single simulation needs to be reduced. For this purpose, the simulation system must be augmented to allow an adaptive level of detail simulation with respect to the process state and requirements. To enable a more exact representation of the workpiece contours, the fictitious domain method must be extended to consider high order boundary descriptions. A further aspect to be investigated by simulation and experiment is the avoidance of introduction of heat into the workpiece by comparison of varying process parameter values and different milling strategies.In accordance with the overall goal of the priority program, the intent of this project is the development and validation of a method which, by avoidance of heat introduction and compensation of unavoidable thermo-mechanical workpiece deformation, computes an NC path that will yield the designed shape in the as-built part and remain within the specified fabrication tolerances.