Development of Machining Center Spindle for Realizing Elliptical Vibration Cutting

研究人员开发了一种新的切削技术——椭圆振动切削技术，与普通切削相比，该技术显著降低了切屑厚度、切削力、切削能量等，大大提高了加工精度。本课题的研究目的是研制一种能承受较大切削载荷的椭圆振动铣床，以加工淬硬钢的模具。为实现该机床，利用双轴机构研制了一种独特的椭圆振动铣削主轴。所开发的机床通过旋转带有内置电机的偏心套，机械地产生刀具的圆周振动运动。设置圆振动的半径为0.5mm，最大频率为167Hz。所研制的机床既可用于夹紧刀主轴的椭圆振动规划，又可用于旋转内刀主轴的椭圆振动立铣削。对淬硬钢进行了CBN和涂层硬质合金刀具的加工试验，证明椭圆振动切削比无椭圆振动运动的常规切削效果更好。利用单晶金刚石刀具进行椭圆振动规划，在淬硬钢上获得了粗糙度约为0.11μm Ra的镜面。在上述研究成果的基础上，研制了一种新型的可附加在加工中心上的圆振动铣削附件。同时进行了附件开发的切削试验，结果表明，可以获得几乎相同的切削性能。

A new cutting technology named elliptical vibration cutting has been developed by the head investigator, by which the chip thickness, the cutting force, the cutting energy, etc. are reduced remarkably and machining accuracy is much improved as compared with the ordinary cutting. The purpose of current research is to develop an elliptical vibration milling machine which can be applied to relatively large cutting loads so that the dies and molds of hardened steel can be machined. In order to realize such a machine, a unique elliptical vibration milling spindle is developed by utilizing a double-spindle mechanism. The developed machine generates circular vibratory motion of the cutting tool mechanically by rotating an eccentric sleeve with a built-in motor. The radius and the maximum frequency of the circular vibration are set to 0.5mm and 167Hz respectively. The developed machine is applied to elliptical vibration planning by clamping the tool spindle, and also to elliptical vibration end milling by rotating the inner tool spindle as well at the same time. The machining tests of hardened steel with CBN and coated carbide tools are carried out, and it was proved that the elliptical vibration cutting shows better results as compared with conventional cutting without elliptical vibration motion. A mirror surface on hardened steel with a roughness of about 0.11μm Ra was obtained by elliptical vibration planning by employing a single crystal diamond tool. Base on the above research results, a new circular vibration milling attachment was developed which can be attached to a machining center. The cutting tests were also conducted with the attachment development, and it was proved that almost the same cutting performance can be achieved.