Experimental and FEM-based Analysis of the thermal loads in deep-hole drilling process using twist drills and MQL

本项目的主要目的是开发一种高效的有限元模拟，以预测在使用麻花钻和最小润滑量(MQL)的复杂铝合金深孔钻削中热引起的工件偏差，并制定适当的补偿策略，最大限度地减少实验工作量。由于这一中心目标，在优先方案(PP)1480的第三阶段也是最后阶段内定义了两个不同的重点。第一个重点是实现高精度和关于计算时间优化的钻削过程的三维仿真，以便在加工过程中和之后实现真实的计算的热和机械引起的工件变形。模型的进一步改进还应该能够绘制出在工件冷却后仍然存在的井眼直线度偏差。该项目的第二个目标是开发三种创新的薪酬技术，这三种技术从根本上是不同的，提供了不同的优势和劣势，因此战略的组合似乎也是合理的。首先，应该分析进给/进给速度/进给速度的工艺适应性，因为较高的进给速度不仅会导致较低的热负荷进入工件，而且还会导致较高的生产率。就冷却剂概念而言，MQL应在项目内进一步使用。热负荷的补偿是通过冷却压缩空气来实现的，由于其在操作、操作安全等方面的优势，是一种合理的低温概念的替代方案。第三种补偿策略是基于机床主轴在轴向进给过程中的同步径向运动。由于这种NC轨迹补偿，可以在加工过程中修改钻削轴，并可以控制钻削方向。除了对这些补偿技术的基础研究外，开发的解决方案将转移到复杂的面向应用的演示组件中。在PP 1480项目的第三个也是最后一个阶段结束时，将介绍一种分析、建模、模拟、预测和补偿热引起的工件偏差的整体方法。

The main aim of this project is the development of a high-efficient finite-element-simulation, in order to predict the thermally induced workpiece deviations in deep-hole drilling of complex aluminium cast alloy components using twist drills and minimum quantity lubrication (MQL) as well as to develop appropriate compensation strategies and to minimize the experimental effort. Due to this central objective, two different focuses have been defined within this third and last stage of the priority program (PP) 1480. The first emphasis is the implementation of a high-precision and with regard to the computing time optimized 3d-simulation of the drilling process, in order to achieve realistic calculated thermally and mechanically induced workpiece deformations during and after the machining process. Further enhancements of the model should also be able to map the borehole straightness deviation which remains after cooling down of the workpiece. The second aim of the project is the development of three innovative compensation techniques, which are fundamentally different and offer diverse advantages and disadvantages so that a combination of the strategies seems to be reasonable, too. At first, the process adaptation of the feed / the feed velocity / should be analyzed, since a higher feed rate not only induces a lower thermal load into the workpiece, but also allows higher productivity. In terms of the coolant concept, the MQL should be used furthermore within the project. The compensation of the thermal load is carried out by cooled compressed air, which is a reasonable alternative to the cryogenic concept, because of its advantages regarding to the handling, operational safety etc. Cryogenic cooling is frequently used in machining of hard-to-cut materials. The third compensation strategy is based on the synchronous radial movement of the machine tool spindle during the axial feed of the tool. Due to this NC-path compensation, the drilling axis can be modified over the machining process and the drilling direction can be controlled. Apart from the fundamental investigation of these compensation techniques the developed solutions will be transferred to complex application oriented demonstration components. At the end of this third and last stage of this project within the PP 1480 a holistic methodology of the analysis, modelling, simulation, prediction, and compensation of the thermally induced workpiece deviations will be presented.