リップ型工具による小口径ガラスロッド端面の球面加工精度

Abstract

Following a proposal of the new convex spherical finishing method using lip type tool, this paper describes the relation between the position errors and the accuracy of the spherical shapes on end of small diameter glass rods. The position errors between the glass rod and the lip type tool axis bring two kinds of effects upon the shapes on them. The position error caused by parallel slide of the glass rod axis toward the lip type tool axis on the plane including the both axes changes only the value of spherical radius, and its rate depends on the top angle of the tool. On the other hand, the position error caused by normal slide of the glass rod axis to the plane deforms the spherical shapes to the aspherical shapes. The expressions of these aspherical shapes are formulated, and the correlative equations between the position error values and the counts of interference fringes of these shapes are also made out. The experiments are performed for optical small diameter glass rod works (φ2.0×L110mm) using lip type grinding tool filled up with 7μm diamonds. The experimental results are that when the position error value ΔZ is 2.5μm toward the normal direction, the spherical shape deforms to aspherical shape having an apical umbilical point at a center of the surface of revolution, and about four peaces of interference fringe appear. Both of them are almost in agreement with the calculated results on the experiments.