Development of Machining Center Spindle for Realizing Elliptical Vibration Cutting

本文研究了椭圆振动切削新技术，与普通切削相比，该技术可显著降低切屑厚度、切削力、切削能量等，提高加工精度。本研究的目的是开发一种椭圆振动铣床，它可以适用于较大的切削载荷，以便加工淬火钢模具。为了实现这样的机器，一个独特的椭圆振动铣削主轴开发利用双主轴机构。所开发的机器通过旋转具有内置电机的偏心套筒来机械地产生切削刀具的圆形振动运动。圆振动的半径和最大频率分别设定为0.5mm和167Hz。所开发的机器是适用于椭圆振动规划的夹紧工具主轴，也椭圆振动端铣旋转内工具主轴以及在同一时间。用CBN和涂层硬质合金刀具对淬硬钢进行了加工试验，证明了椭圆振动切削比无椭圆振动的常规切削具有更好的加工效果。用单晶金刚石刀具在淬硬钢上进行椭圆振动刨削，获得了粗糙度为0.11μ mRa的镜面。在上述研究的基础上，研制了一种可安装在加工中心上的新型圆振动铣削附件。并进行了切削试验，结果表明，该附件的切削性能基本相同。

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.