High speed analysis of the chip formation in small diameter deep hole drilling of high-strength and difficult-to-machine materials

本研究项目的目的是深入分析小直径深孔钻削中的切屑形成，为高强度和难加工材料的高效可靠加工奠定基础。以工业应用为中心，对镍基合金、钛合金和贝氏体钢的精密切削进行了研究。在小直径深孔钻削中，切屑的形成对工艺的稳定性至关重要。不利的切屑形状的形成，即长切屑导致切屑槽堵塞，并最终导致刀具破损。此外，不利的切屑形状的发展促进了所产生的切屑与钻孔壁之间的接触，并因此导致表面质量的降低。在本研究项目中，一个特定的实验装置将提供一个具体的芯片形成分析。由难以加工的材料制成的棒材插入透明且光学上无缺陷的刀具中进行扩孔，将由高速摄像机拍摄，从而为沿着切削部分的切屑形成和沿着沿着排屑槽的切屑去除提供有价值的见解。在单唇深孔钻进行的调查中，使用高速摄像机的创新实验装置将被推进，随后用于分析工艺数据和切削刃设计对切屑形成的影响。此外，切屑形成的模拟将用于获得进一步的知识的主要机制的切屑形成。在这种情况下，宏观切削刃设计对切屑形成的影响将通过模拟进行详细分析。因此，将确定在具有挑战性的材料中实现高效深孔钻削的适当工艺和工具参数。此外，高速分析将用于检查枪钻的周向接触元件上的冷却剂润湿性。导向垫和圆形磨削倒角的润湿性与发生的磨损和所产生的表面质量直接相关。在这方面，将比较具有不同钻头锥度、圆周形状和供油横截面的工具的定性和定量润湿性。在确定有利工艺和刀具参数的高速分析之后，将进行固体材料的实验测试。小直径单唇深孔钻削的试验将集中在大长径比钻孔的制造上。进行的实验工作的评价考虑刀具载荷，切屑形成，刀具磨损以及质量方面的尺寸和形状公差，表面质量，重铸层的变化。

The aim of this research project is to analyze the chip formation in small diameter deep hole drilling in-depth to set the stage for a productive and reliable machining of high-strength and difficult-to-machine materials. Focusing on industrial applications the machining of a nickel based alloy, a titanium alloy and a bainitic steel are investigated accurately. In small diameter deep hole drilling the chip formation is crucial for process stability. The formation of disadvantageous chip shapes respectively long chips leads to a chip flute plugging and finally results in tool breakage. Furthermore the development of disadvantageous chip shapes facilitates a contact between produced chips and the bore hole wall and thus causes a reduction of the surface quality. In this research project a specific experimental set-up will offer a substantiated chip formation analysis. The counterboring of bars made of difficult-to-machine materials, inserted in transparent and optically flawless glas, will be captured by a high-speed-camera and hence provide valuable insights into the chip formation along the cutting part and the removal of chips along the chip flute. Within the investigations conducted in single lip deep hole drilling the innovative experimental setup using a high-speed-camera will be advanced and subsequently used to analyze the influence of the process data and the cutting edge design on the chip formation. Moreover a simulation of chip formation will be used to gain further knowledge of the predominant mechanisms of chip formation. In this context the influence of the macroscopic cutting edge design on the chip formation will be analyzed in detail by means of the simulations. Thus, adequate process and tool parameters leading to an efficient deep hole drilling in the challenging materials will be identified. In addition, the high speed analysis will be applied to check the coolant wettability on the circumferential contact elements of the gun drills. The wettability of the guide pad and of the circular grinding chamfer correlates directly with the occurring wear and the produced surface quality. In this connection, tools with varying drill head tapering, circumferential shapes and cross-sections for oil supply will be compared regarding the qualitative and quantitative wettability. Subsequent to the high speed analysis for the identification of advantageous process and tool parameters, experimental tests with solid material will be conducted. The tests on small diameter single lip deep hole drilling will focuse on the manufacturing of bore holes with high length-to-diameter-ratios. The evaluation of the experimental work conducted considers tool loads, chip formation, tool wear as well as quality with respect to dimensional and form tolerances, surface quality, and alteration of recast layer.