US 5,308,200 A · Method of producing a die forming lens fisheye steps

Abstract

A method of producing a die for use in forming fisheye steps in an automobile lens having both straight and curved portions. The plurality of fisheye steps formed on the curved portion of the lens are divided into generally parallelogram-like sections. The die comprises plural concave portions that are arranged to form the fisheye steps when applied in a lens forming process. In the die producing method, the boundary lines between concave portions corresponding to the respective fisheye steps are connected to produce approximately a straight line, to thereby improve an appearance of the fisheye steps. Further, the concave portions that are divided by longitudinal lines extending in a first direction and lateral lines obliquely intersecting the longitudinal lines and extending in a second direction are produced by NC machining using an end mill. The end mill is controlled to have a locus generally in parallel with the longitudinal lines, in which vector control is added when the end mill passes a start side lateral line that is expected to become a boundary between the concave portions and passes an end side lateral line to enter the next concave portion so that the locus of the end mill becomes perpendicular to these lateral lines.

Claims3

Dependent claims

A method of producing from a die workpiece block a die to be used for forming, on a lens having a curved portion, a plurality of fisheye steps that are divided by boundary lines into generally parallelogram-like sections, said die being divided into a plurality of concave portions corresponding to the respective fisheye steps by a first group of boundary lines extending in a first direction and a second group of boundary lines extending in a second direction, said method comprising the steps of:

(1) entering a cutting tool into a divided section of said die block corresponding to one concave portion while controlling an entrance movement direction of said cutting tool so that is locus becomes perpendicular to a start side boundary line comprising a first one of said second group of boundary lines and specified to become a boundary of said divided section;
(2) moving said cutting tool relative to said die block so that said cutting tool proceeds generally in parallel with the boundary lines of said divided section belonging to said first group of boundary lines;
and
(3) controlling a relative exit movement direction of said cutting tool so that the new locus of said cutting tool becomes perpendicular to a specified end side boundary line comprising a second one of said second group of boundary lines, wherein:
said second group of boundary lines is formed substantially as a straight line, said second group of boundary lines obliquely intersecting said first group of boundary lines.

2 more elements

Dependencies are inferred from the claim text.

Method of producing a die forming lens fisheye steps

Life of this patent

Method of producing a die forming lens fisheye steps

Life of this patent

Abstract

Claims3