Development of spindle with motor function for ultra-precision machine tool

点击翻译按钮获取中文摘要

A purpose of this study is to develop a new spindle for ultra-precision machine. A distinction between the spindle and conventional spindle for ultra-precision machine tools is that proposed spindle uses water flow to generate power for spindle operation. In contrast, conventional spindle for the ultra-precision machine tools uses electric power. In the spindle, the water flow is utilized for important three functions of the spindle. The three functions are the follows;(1) Support function: water hydrostatic bearings support the spindle body,(2) Motor function: flow channels with simple geometries are designed inside the spindle body so that the water flow through the channels generates torque to rotate spindle body, and(3) Cooling function: temperature controlled water minimizes the spindle deformation.This study proposes the principle and structure of the spindle. A design procedure for the spindle is then introduced. Based on the procedure, software to determine a combination of optimum parameters was developed so that highest efficiency of the spindle can be obtained. In this study, optimum parameters to design the spindle with the following specifications were calculated by developed software.(1) Rated rotational speed: 10,000 rpm(2) Rated power: 50W(3) Rated stiffness of the water hydrostatic bearings: 50 N/μm.Experiments were carried out to investigate performances of the developed spindle. The experiments show smooth operations of the spindle, which indicates correct operations of the hydrostatic bearings and motor of the spindle. In addition, the experiments verify that performances of the motor and cooling function satisfy the design requirements. In contrast, stiffness of the water hydrostatic bearings does not reach the level of the specification, due to mainly the characteristic of the restrictors in the bearings. In future work, improvements of the bearing stiffness will be attained by altering diameter of the restrictors.