Development of Machining Center Spindle for Realizing Elliptical Vibration Cutting

研究人员开发了一种新的切割技术--椭圆振动切割，与普通切割相比，它显著减小了切屑厚度、切削力、切削能等，加工精度大大提高。本课题研究的目的是研制一种适用于较大切削力的椭圆振动铣床，以便加工淬硬钢的模具。为了实现这种机床，利用双主轴机构研制了一种独特的椭圆振动铣床主轴。开发的机床通过旋转带有内置电机的偏心套筒来机械地产生刀具的圆周振动运动。圆周振动半径和最大频率分别设置为0.5 mm和167 Hz。研制的机床既可用于夹持刀具主轴的椭圆振动规划，也可用于旋转内刀具主轴的椭圆振动立铣刀。用CBN刀具和涂层硬质合金刀具对淬硬钢进行了加工试验，结果表明，椭圆振动切削比无椭圆振动的常规切削效果更好。利用单晶金刚石刀具对淬火钢表面进行椭圆振动加工，获得了表面粗糙度约为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安装在加工中心上的环形振动磨削附件。并结合附着体的研制进行了切割试验，证明可以获得几乎相同的切割性能。

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.