Fundamental investigations on micro single-lip deep hole drilling of challenging drilling situations

为了在钻孔过程开始时稳定工具，深孔钻孔工具需要导孔或钻套形式的钻导向器。在复杂的钻孔情况下，用于深孔钻孔的常规工艺链（包括面铣、机械导向孔钻孔和随后的深孔钻孔）可以通过用激光导向孔钻孔工艺代替面铣和机械导向孔钻孔而显著缩短。除了提高生产率外，激光加工还可以在表面硬化部件上无磨损地钻制导向孔。申请的研究项目是DFG上一个项目的后续，在该项目的框架内，对使用单激光脉冲生成激光导孔以及在要求苛刻的钻孔情况下激光导孔钻孔和单唇深孔钻孔的工艺组合进行了广泛的研究。基于这些结果，本项目的目的是通过使用激光螺旋钻孔来扩展激光钻孔过程的灵活性，迄今为止，激光钻孔过程在可行的钻孔直径方面受到单脉冲的限制。通过将材料烧蚀分布在大量的激光脉冲上，还将减小激光孔的圆度偏差。确定了用于加工X2 CrNiMo 17 -12-2和20 MnCr 5材料的合适激光参数，然后对使用该工艺组合时的刀具寿命和钻孔质量进行了研究。由于熔化物在钻孔壁处的固化，与机械产生的钻孔相比，激光钻孔显示出较低的钻孔质量。因此，本项目的另一个目的是使用阶梯钻通过阶梯钻的第二阶梯加工整个钻孔表面，从而显著提高钻孔质量。对于使用阶梯钻加工表面硬化的部件，需要进行局部热处理，以降低切削刃接触区域的材料硬度。将使用热模拟来确定实现所需温度窗口的合适激光参数。由于选择性激光熔化等创新增材方法的使用越来越多，具有复杂表面轮廓的部件比例也越来越高，因此要求苛刻的钻孔情况也越来越多。该研究项目的另一个目标是使用增材制造的导向孔在要求苛刻的钻孔情况下进行深孔钻孔的基础研究。研究的重点是附加孔的高粗糙度对刀具磨损和刀具导向的影响。

In order to stabilize the tool at the beginning of the drilling process, deep hole drilling tools require a drill guide in the form of pilot holes or drill bushes. The conventional process chain for deep hole drilling in complex drilling situations, consisting of face milling, mechanical pilot hole drilling and subsequent deep hole drilling, can be significantly shortened by substituting face milling and mechanical pilot hole drilling with the laser pilot hole drilling process. In addition to increasing productivity, laser processing also enables the wear-free drilling of pilot holes in case hardened components. The research project applied for follows on from the DFG last project, within the framework of which extensive investigations were carried out on the generation of laser pilot holes using single laser pulses and on the process combination of laser pilot hole drilling and single-lip deep hole drilling in demanding drilling situations. Based on the results, the aim of this project is to extend the flexibility of the laser drilling process, which has so far been limited by the single pulse with regard to the feasible bore hole diameters, by the use of laser helical drilling. By distributing the material ablation over a large number of laser pulses, the roundness deviation of the laser bore is also to be reduced. The identification of suitable laser parameters for the processing of the materials X2CrNiMo17-12-2 and 20MnCr5 is followed by investigations on tool life and bore hole quality when using the process combination. Due to the solidification of the melt at the bore hole wall, laser drillings show a lower bore hole quality compared to mechanically produced bore holes. Therefore, a further aim of this project is to use a step drill to machine the entire bore hole surface through the second step of the step drill thus significantly increasing the bore hole quality. For the machining of case hardened components with the step drill, a local heat treatment is required to reduce the hardness of the material in the contact area of the cutting edges. A thermal simulation will be used to identify suitable laser parameters for the realization of the required temperature window. Due to the increasing use of innovative additive methods like selective laser melting, the proportion of components with complex surface contours and thus demanding drilling situations is increasing. A further goal of this research project is the fundamental investigation of deep hole drilling in demanding drilling situations using additive manufactured pilot holes. The focus of the investigations is on the influence of the high roughness of the additive holes on tool wear and the guidance of the tool.