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分析小直径深孔深度钻削时的切屑形成，为高强度难加工材料的高效可靠加工奠定基础。针对工业应用，对镍基合金、钛合金和贝氏体钢的加工进行了精确的研究。在小直径深孔钻井中，切屑形成对工艺稳定性至关重要。形成不利于切屑形状的长切屑，导致切屑槽堵塞，最终导致刀具断裂。此外，不利的切屑形状的发展促进了所生产的切屑与钻孔壁之间的接触，从而导致表面质量的降低。在这个研究项目中，一个特定的实验装置将提供一个证实的芯片形成分析。由难以加工的材料制成的棒的反镗，插入透明和光学完美的玻璃中，将被高速摄像机捕获，从而提供沿切割部分的切屑形成和沿切屑槽去除切屑的宝贵见解。在对单唇深孔钻孔进行的研究中，采用高速摄像机的创新实验装置将被推进，并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，对晶片形成的模拟将用于进一步了解晶片形成的主要机制。在此背景下，将通过仿真详细分析宏观刃口设计对切屑形成的影响。因此，将确定适当的工艺和工具参数，从而在具有挑战性的材料中进行有效的深孔钻探。此外，高速分析将应用于检查冷却剂润湿性的周向接触元件的枪钻。导向垫和圆磨倒角的润湿性直接关系到所发生的磨损和所生产的表面质量。在这方面，将比较不同钻头锥度、周向形状和供油截面的工具在定性和定量上的润湿性。在高速分析确定有利工艺和刀具参数之后，将进行固体材料的实验测试。小直径单唇深孔钻削试验将侧重于高长径比孔的制造。对所进行的实验工作的评估考虑了刀具载荷、切屑形成、刀具磨损以及与尺寸和形状公差、表面质量和重铸层变化有关的质量。

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.