Ultraprecision cutting of graphite with monocrystalline diamond tools

单晶金刚石刀具超精密切割石墨

• 批准号: 471319837
• 负责人: Professor Dr.-Ing. Eckart Uhlmann
• 金额: --
• 依托单位: Fachgebiet Werkzeugmaschinen und Fertigungstechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/471319837?language=en
• 关键词: Ultraprecision; cutting; graphite; monocrystalline; diamond

Modern air bearings made of graphite depend on highest requirements concerning shape accuracies as and surface qualities. Air bearings are characterised by good sliding, try and emergency running properties, can reach high stiffness and show a high fatigue strength as well as a good shape resistance, which results in an increasing demand for industrial applications. Unfortunately, the machining of graphite shows a high breakout behaviour as well as a considerable tool wear. In order to machine the air bearings made of graphite concerning the high requirements, the ultra-precision machining represents an established manufacturing process and enables the fabrication of surface roughness values in the single-digit nanometer range and shape accuracies as in the submicrometer range. The cutting materials made of polycrystalline diamond (PCD) and chemical-vapour-deposition(CVD)-diamond, which were conventionally used show a considerable higher radius waviness WR, rounded cutting edge radius rβ and crack growth Cg compared to monocrystalline diamonds (MCD). Therefore, tools made of MCD are applied. Using the specific geometric properties of the MCD tools e.g. the rounded cutting edge radius rβ leads to different process conditions, which changes the stress conditions, the effect of the forces as well as the breakout behaviour. The aim of the research project is the identification of the separation mechanisms and the breakout behaviour during the machining of graphite with tools made of MCD. In order to reduce the breakout rate ξB and the tool wear, a transcrystalline cutting process is to be achieved.To realise the research project, the used graphite materials are characterised as well as the basic separation mechanisms will be obtained and detailed wear investigations of the MCD-tools are carried out. In order to analyse the breakout rate ξB and the tool wear, investigations concerning of ultra-precision turning are applied. Based on this, an explanatory model will be developed, which describes the mechanisms during the cutting process. In order to show the temperatures ϑ and the pressure loads during the cutting process, a particle-based simulation is carried out. This simulation model enables the time determination of the tribo-chemical tool wear. The results of the research project provide a fundamental knowledge of the cutting process and the breakout behaviour of graphite materials using MCD with a reduced tool wear.

石墨制成的现代空气轴承对形状精度和表面质量有着极高的要求。空气轴承具有良好的滑动、尝试和紧急运行性能，可达到高刚度，并显示出高疲劳强度以及良好的抗变形性，这导致工业应用的需求不断增加。不幸的是，石墨的加工显示出高的漏钢行为以及相当大的刀具磨损。为了加工由石墨制成的空气轴承，超精密加工代表了一种既定的制造工艺，并且能够制造个位数纳米范围内的表面粗糙度值和亚微米范围内的形状精度。与单晶金刚石（MCD）相比，常规使用的由多晶金刚石（PCD）和化学气相沉积（CVD）金刚石制成的切削材料显示出相当高的半径波纹度WR、圆形切削刃半径rβ和裂纹生长Cg。因此，应用MCD制成的工具。使用MCD刀具的特定几何特性（例如圆形切削刃半径rβ）会导致不同的工艺条件，从而改变应力条件、力的影响以及崩落行为。该研究项目的目的是确定使用MCD制成的工具加工石墨过程中的分离机制和漏钢行为。为了降低漏钢率B和刀具磨损，将实现穿晶切削工艺。为了实现该研究项目，将对所用石墨材料进行表征，并获得基本的分离机制，并对MCD刀具进行详细的磨损调查。为了分析超精密车削的漏钢率B和刀具磨损，进行了有关超精密车削的研究。在此基础上，将开发一个解释模型，它描述了在切割过程中的机制。为了显示切削过程中的温度变化和压力载荷，进行了基于粒子的模拟。该仿真模型能够确定摩擦化学工具磨损的时间。该研究项目的结果提供了使用MCD的石墨材料的切削过程和漏钢行为的基本知识，同时减少了刀具磨损。