| 摘要 |
PURPOSE:To manufacture a Fresnel lens molding tool of high precision by nickel plating the substrate for the molded face with electroless nickel to prepare a nickel layer and form the plate and forming the molded face by means of cutting with diamond tool on the plate. CONSTITUTION:An original plate 13 is formed with stainless tool steel as parent material of the mold into the shape of column, hardened and abraded to manufacture the substrate 14 on which a nickel layer 19 made by electroless nickel coating is prepared. Next, the outer circumference of the said original plate is cut with the diamond tool to finish in the specified dimensions and manufacture the plate 20. Then, with the diamond straight tool for machining the serrated groove, the serrated grooves 2a, 3a,... having concaves and convexes corresponding to those of the principal surface 1 are provided by cutting to form up the molded face 16. The molded face is free from pinholes and the like, also free from transformations after being machined, and is transferred the machining accuracy as it is, so that by enhancing the cutting accuracy a Fresnel lens molding tool of high accuracy can be obtained.
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