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

为了在钻井过程开始时稳定工具，深孔钻井工具需要导向孔或钻套形式的钻具导向件。用激光导孔工艺代替端面铣削和机械导孔，可以大大缩短复杂钻进条件下传统的深孔加工工艺链条。除了提高生产率，激光加工还可以在表面硬化的部件上无磨损地钻孔导孔。申请的研究项目是DFG上一个项目的后续项目，在该项目的框架内，对利用单激光脉冲产生激光导孔以及在苛刻的钻井环境下激光导孔和单唇深孔的组合工艺进行了广泛的研究。根据结果，该项目的目的是通过使用激光螺旋打孔来扩展激光打孔工艺的灵活性，目前为止，在可行的钻孔直径方面，激光打孔过程一直受到单一脉冲的限制。通过将材料烧蚀分布在大量的激光脉冲上，还可以减小激光炮孔的圆度偏差。确定了适合加工X2CrNiMo17-12-2和20MnCr5材料的激光参数，并对采用该工艺组合时的刀具寿命和孔质量进行了研究。由于熔体在钻孔壁上的凝固，激光钻孔与机械钻孔相比，显示出较低的钻孔质量。因此，该项目的另一个目标是使用阶梯钻头通过阶梯钻头的第二步加工整个钻孔表面，从而显著提高钻孔质量。对于用阶梯钻加工表面硬化的零件，需要进行局部热处理，以降低切削刃接触区域中材料的硬度。将使用热模拟来确定实现所需温度窗口所需的适当激光参数。由于选择性激光熔化等创新添加剂方法的使用越来越多，因此具有复杂表面轮廓的零件的比例正在增加，因此对钻孔情况的要求也越来越高。这项研究项目的另一个目标是在要求苛刻的钻井环境中使用附加制造的导向孔进行深孔钻探的基础研究。重点研究了加工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.