Development of High-accurate and High-efficient Centerless Grinding Technology for Micro Cylindrical parts

为发展微小圆柱形零件的高精度、高效率加工技术，提出了一种无调整轮无心磨削新方法。在这种方法中，代替调整轮的是超声振动瓦，其端部在高频下进行椭圆运动，用于与刀片一起支撑工件。工件的转速由滑块末端的椭圆运动控制。此外，鞋的进给运动是由一个精细的进给单元。这项工作可归纳如下。(1)设计并制造了由滚珠丝杠、步进电机、直线导轨和靴座保持器组成的超声波靴和精密进给装置。在现有的无心磨床上安装了超声波靴和精密进给装置，搭建了实验装置。(2)本文用激光测振仪研究了在不同电压和频率的交流电压作用下，鞋在椭圆运动中的性能。(3)对直径为5 mm的工件进行了旋转驱动试验。证实了利用滑靴末端的椭圆运动可以实现对工件转速的控制。(4)工件的转速取决于靴形件的弯曲振动速度，随着电压的增大而增大，随着频率向靴形件共振点的靠近而增大。(5)对直径为1 ~ 5 mm的针形工件进行了磨削试验。结果表明，最小引脚直径为500μm，圆度由20μm提高到1.5μm。

To develop a high-accurate and high-efficient machining technology for micro cylindrical parts, a new centerless grinding method without using the regulating wheel has been proposed. In this method, instead of the regulating wheel an ultrasonic vibrating shoe, the end of which is in elliptic motion at a high frequency, is employed to support the workpiece together with the blade. And the rotational speed of workpiece is controlled with the elliptic motion on the end of shoe. In addition, the in feed motion of shoe is given by a fine feeding unit. This work can be summarized as follows.(1) An ultrasonic shoe and a fine feeding unit composed of a ball screw, a stepping motor, a linear guide and a shoe holder have been designed and produced. Then an experimental apparatus has been constructed by installing the ultrasonic shoe and the fine feeding unit on an existing centerless grinder.(2) The performance in the elliptic motion of shoe has been investigated with a laser vibrometer when the AC voltage is applied for various voltages and frequencies.(3) Tests of rotationally driving the workpieces with sizes of 5mm in diameter have been conducted on the constructed apparatus. It is confirmed that the workpiece rotational speed can be controlled with the elliptic motion of the end of shoe.(4) The workpiece rotational speed depends on the bending vibration velocity of shoe, increasing with lager voltage and as the frequency become closer to the resonance points of shoe.(5) Grinding tests of pin-shaped workpieces with sizes of 1mm to 5mm in diameter have been carried out. As the results, the diameter of the smallest pin ground is 500μm, and the roundness improved from 20μm to 1.5μm.