Coupling of analytical and numerical models to simulate the thermomechanical interactions during the milling of complex workpieces

在复杂薄壁零件结构的铣削加工过程中，会产生变形。这些偏差是由机械和热工艺影响引起的，可能会对加工结果产生很大影响。因此，优先方案的主要目标是对工程三个阶段的热变形进行建模、仿真并最终进行补偿。在第三个拟议阶段内，应使用适当的方法来减少热致变形。测量结果表明，通过改变工艺参数，可以很大程度上减少工件的变形。因此，应采取两阶段办法，一方面区分过程方面的方法，另一方面区分补偿战略。加工侧方法通过改变加工参数(加工速度v_c、每齿进给量f_z)或改变加工深度(A_P)与宽度(A_E)之比来改变加工策略。然而，补偿策略要么通过倾斜刀具来提供工件的变形来破坏路径规划，要么通过附加的致动器来机械地或热地抵消变形。与补偿策略相反，前面提到的两种减少方法与较高的技术工作量有关，只有在工艺方面的策略不足以维持所需的容差时才使用。在项目的前两个阶段开发和验证的过程模型为两种减少方法奠定了基础。该模型能够模拟任何可加工几何形状在铣削过程中产生的变形，从而可以推导出避免变形发生前的减缩方法。

During the milling process of complex thin-walled workpiece structures, deformations occur. These deflections are caused by mechanical and thermal process influences and may substantially affect the machining results. Therefore, the main objective of the priority program is the modeling, the simulation and ultimately the compensation of the thermally caused deformations in the course of three project phases.During the first two phases of the project the modeling and the simulation of the deformation was treated. Within the third proposed phase, appropriate methods should be used to reduce thermally induced deformations. Measurements demonstrate a high potential for the reduction of workpiece deformations through a variation of process parameters. Therefore, a two-staged approach should be pursued, which differentiate between process sided methods on the one hand and compensation strategies on the other hand. The process sided approach pursues a change of the machining strategy by a modification of the process parameters (cutting speed v_c, feed per tooth f_z) or by changing the ratio between cutting depths (a_p) and widths (a_e). However, the compensation strategies either impair the path planning by providing the deformation of the workpiece by means of tilting the tool or counteract the deformations mechanically or thermally with additional actuators. Contrary to the compensation strategy the first two mentioned reduction methods are associated with a high technical effort and are only used, if process sided strategies are insufficient to maintain required tolerances. A process model, which was developed and validated within the first two phases of the project, builds the basis of both reduction methods. This model is able to simulate the deformations caused by the milling process of any machinable geometry so that reduction methods to avoid deformations before they are occurring can be derivated.