Microstructure of Cutting Edge Affecting Minimum Thickness of Cut in Micromachining

当切屑厚度很小时，切屑去除过程发生了从稳定到不稳定的转变。有效切削厚度是指切削刃从工件表面上有效去除的工件材料的未变形厚度，在过渡处可以定义为最小切削厚度。最小切割厚度决定了可达到的切割精度的可能限制。分析了金刚石切削刃微观结构对最小切削厚度的影响。研究结果如下：针对微细加工现象的分析，设计并制作了一套采用空气主轴和静压滑台的专用切削装置。该装置具有高刚度、高运动重复性和进给机构的纳米级精度等特点。结果表明，切削刃的锋利度是影响切削性能的主要因素 ...更多信息 影响最小切削厚度的玛丽因子，切削刃越锋利，最小切削厚度越小。在切削刃有效长度上组织的均匀性也是实现稳定排屑的重要因素。边缘形状的不均匀性会降低切削性能，本文用二维有限元法分析了微机械加工中弹性切屑分离过程的初始阶段。当具有一定刃口半径的切削刃被压入时，在刀具和工件之间的界面上的工件倾向于分成两个方向，即前刀面侧和后刀面侧。刀具边缘上的分离点根据切削厚度和刀具与工件之间的相互作用力而变化。通过分析，估算出最小切屑厚度约为切削刃锋利度半径的0.7倍。该比值随刀具与工件间作用力的增大而增大。少

At an extremely small thickness of cut, a transition takes place in chip removal process from stable to unstable. The effective thickness of cut, which is the undeformed thickness of the workmaterial effectively removed by cutting edge from the worksurface, at the transition can be defined as the minimum thickness of cut. The minimum thickness of cut determines the possible limitation of the cutting accuracy attainable. The purpose of the present work is to analyse the effects of microstructure of a diamond cutting edge to minimum thickness of cut. The results obtained in the work are shown as follows.For the analysis of micromachining phenomena, a special cutting apparatus is designed and built using an air spindle and a hydrostatic slide. It has features of high stiffness, high repeatability in motion and nanometer resolution in infeed mechanism.Cutting experiments are carried out on the cutting apparatus described above. The results show that the sharpness of cutting edge is the pri … More mary factor which affects the minimum thickness of cut and that the sharper the cutting edge, the smaller the minimum thickness of cut. The uniformity of microstructure over the effective length of cutting edge is also the important factor enabling the stable chip removal. Lack of uniformity in the edge configuration deteriorates the cutting performance in terms of minimum thickness of cut.Using a two-dimensional finite element method, the initial stage of elastic chip separation process in micromachining is analysed. When the cutting edge with a certain edge radius is indented, the workmaterial on the interface between the tool and the workmaterial tends to separate into two directions, rake face side and flank face side. The separation point on the tool egde changes depending on the thickness of cut and the interaction force between the tool and the workmaterial. By the analysis, the minimum thickness of cut is estimated to be about 0.7 of the radius of the cutting edge sharpness. That ratio tends to incease with the increase of the interaction force between the tool and the workmaterial. Less