Development of a New Ultra-precision Finishing Process for Internal Surface by the Application of Magnetic Abrasive Machining Using Superconducting Coil

本文历时三年的研究成果总结如下：(1)本实验室首次采用冷冻型超导电磁线圈实现了工作区内3T （30000 g）的高磁场强度。(2)在超导线圈装置上安装了非铁磁性细长管（SUS304细长洁净管）的内部精加工装置。(3)通过实验结果，分别探讨了采用掺有超细磨粒和铁粒的混合型磁流体进行管内超精密精加工的机理。(4)实验表明，磨粒直径（铁粒直径）和N-S磁极排列决定的磁场强度及其梯度的乘积对精磨压力均有影响。(5)利用传统直流电磁线圈和稀土永磁体建立了模拟实验装置，研究了磁场分布对精加工压力的影响。(6)用个人计算机对工作区内磁场分布的有限元分析结果与用特斯拉-米传感器得到的实测值是相等的。(7)通过有限元分析，讨论了N-S极排列与N-N（或S-S）极排列磁场分布的区别。(8)通过实验明确了N-N极排列对精加工特性的影响，并与N-S极排列进行了比较。(9)利用超导线圈的研究，在精密加工技术研究领域实际获得了极高的3T磁场强度。

The results obtained in this research during three years are summarized as follows :(1) High magnetic field strength of 3T (30000 Gs) in the working zone are first realized in our laboratory using freezing type superconducting electro-magnetic coil. (2) The internal finishing setup for non-ferromagnetic slender tubes (slender clean pipes of SUS304) was equipped on this supercoducting coil apparatus. (3) The mechanism of the internal ultra-precision finishing of a tube is discussed by the experimental results using mixed type magnetic fluid with ultra-micro abrasive grains and iron particles respectively. (4) From the experiments, it is clarified that the finishing pressur is infulenced by the both magnetic abrasive particle diameter (iron particle dia.) and the product value of the magnetic field strength and its gradient determined by N-S magnetic pole arrangemet. (5) The effect of magnetic field distribution on the finishing pressure by the modelling experimental setup using a conventional DC electromagnetic coil and rare earth permanent magnets. (6) The analytic results of the magnetic field distribution in the working zone by the Finite Element Method (FEM analysis) using a personal computer are equal to the measued value obtained using a tesla-meter sensor. (7) The difference between the magnetic field distribution of N-S pole arrangement and N-N (or S-S) pole arrangement is discussed by the FEM analysis. (8) The effects of N-N pole arrangement on the finishing characteristics are clarified experimentally, compared with N-S pole arrangement. (9) By this research using superconducting coil, very high magnetic field strength of 3T was actualy obtained in the research field of precision machining technology.