Effect of material microstructure and tool geometry on surface generation in single point diamond turning
Effect of material microstructure and tool geometry on surface generation in single point diamond turning
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DOI：
10.1016/j.precisioneng.2014.01.002
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发表时间：
2014-07
影响因子：
3.6
通讯作者：
M. Tauhiduzzaman;S. Veldhuis
中科院分区：
文献类型：
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作者：
M. Tauhiduzzaman;S. Veldhuis
工业中有一种强烈的愿望，即在进行超精密单点金刚石车削（SPDT）时提高表面光洁度，以减少满足最终产品规格所需的后处理抛光量。然而，SPDT中有一些众所周知的因素限制了可实现的表面光洁度。本文重点研究了材料微观结构的作用，包括晶界密度和夹杂物的存在，以及刀具设计对表面粗糙度的影响。尺寸效应可以描述为材料微观结构尺寸和相对于切削刃半径的未切削切屑厚度的相对尺寸之间的相互作用。由于晶粒尺寸和位错密度是尺寸效应的可控参数之一，因此对轧制和搅拌摩擦过程（FSP）的机械应变硬化细化的样品进行了对照研究。观察到使用FSP制备的超细晶工件可以减少侧流以及晶界和夹杂引起的粗糙度。使用圆形主切削刃和平坦次切削刃的刀具，研究了刀具几何形状对材料诱导粗糙度的影响。当加工平面表面时，观察到使用平坦的二次边缘可以改善表面光洁度。这种改进主要归功于侧流和材料微观结构效应的减少。通过结合这些方法，SPDT在平面上的平均表面粗糙度值为0.685 nm。此外，定制工具有可能显著提高SPDT的生产率，允许更高的进给速度，同时仍然实现高质量的表面光洁度。
There is a strong desire in industry to improve surface finish when performing ultra-precision, single point diamond turning (SPDT) to reduce the amount of post process polishing required to meet final product specifications. However there are well known factors in SPDT which limit achievable surface finish. This paper focuses on the role of material microstructure, including grain boundary density and the presence of inclusions, as well as tool design on surface roughness using the concept of size effect. Size effect can be described as an interplay between the material microstructure dimension and the relative size of the uncut chip thickness with respect to the cutting edge radius. Since one of the controllable parameters in size effect is grain size and dislocation density, controlled studies were performed on samples whose microstructure was refined by mechanical strain hardening through rolling and a friction stir process (FSP). The use of the ultra-fine grained workpiece prepared using an FSP was observed to reduce side flow as well as grain boundary and inclusion induced roughness. The role of tool geometry on material induced roughness was investigated using a tool with a rounded primary cutting edge and a flat secondary edge. The use of the flat secondary edge was observed to improve surface finish when machining a flat surface. This improvement was primarily attributed to a reduction in side flow and material microstructural effects. By combining these approaches an average surface roughnessRavalue of 0.685 nm was achieved when SPDT a flat surface. Furthermore the custom tool has the potential to significantly improve the productivity of SPDT by allowing for a much higher feed rate while still achieving a high quality surface finish.