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少量润滑（MQL）的复杂铝铸合金部件深孔钻削时热致工件偏差，并制定适当的补偿策略，并最大限度地减少实验工作量。由于这一中心目标，在优先计划（PP） 1480的第三阶段和最后阶段确定了两个不同的重点。第一个重点是实现高精度和计算时间优化的钻孔过程3d模拟，以便在加工过程中和加工后实现实际计算的热和机械引起的工件变形。该模型的进一步增强还应该能够映射出工件冷却后仍然存在的钻孔直线度偏差。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，提供了不同的优点和缺点，因此将这些策略结合起来似乎也是合理的。首先，应分析进给量/进给量速度/的工艺适应性，因为较高的进给量不仅可以降低工件的热负荷，还可以提高生产率。就冷却剂的概念而言，MQL应在项目中进一步使用。热负荷的补偿是通过冷却的压缩空气进行的，这是一个合理的替代低温概念，因为它在处理，操作安全等方面具有优势。低温冷却常用于难切削材料的加工。第三种补偿策略是基于机床主轴在刀具轴向进给过程中的同步径向运动。由于这种nc路径补偿，可以在加工过程中修改钻孔轴，并且可以控制钻孔方向。除了对这些补偿技术的基础研究之外，开发的解决方案将被转换为面向复杂应用的演示组件。在PP 1480项目的第三阶段和最后阶段结束时，将提出热诱导工件偏差的分析、建模、仿真、预测和补偿的整体方法。

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.