Mold machining method using end mill

Patent metadata

Field	Value
Publication number	US-11697164-B2
Application number	US-202016784846-A
Country	US
Kind code	B2
Filing date	Feb 7, 2020
Priority date	Aug 24, 2017
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

A mold machining method using an endmill, the contour of a cross section of the mold being concave and continuous in an area, a ratio of the maximum to the minimum of radius of curvature of the contour of a portion of the area (a first area) being 2 or greater, and a blade of the endmill having a second area where the contour of a cross section is similar to the contour of the first area, the method comprising the steps of determining a spiral path of the endmill such that each point of the first area is machined by a portion of the second area, corresponding to said each point in the similarity, and a radial interval between the spiral tool path is maximized while keeping surface roughness of the machined mold at or below a predetermined value; and machining the mold along the path.

First claim

What is claimed:

1. A mold machining method using an end mill, wherein the mold is used for a lens, the mold has an area in which the contour of a cross section containing an axis of the mold, the axis corresponding to a central axis of the lens, is concave and continuous, a portion of the area is referred to as a first area, a ratio of the maximum value to the minimum value of radius of curvature of the contour of the first area is 2 or greater, and a blade of the end mill has a second area in which the contour of a cross section containing the axis of rotation of the end mill is geometrically similar in shape to the contour of the first area, the method comprising the steps of:
determining a spiral path of the end mill around the axis of the mold such that each point on the contour of the first area is machined by a portion of the second area, the portion of the second area corresponding to said each point on the contour of the first area, and surface roughness of the machined mold is kept at or below a predetermined value; and
machining the mold with the end mill along the path.

2. The mold machining method using an end mill according to claim 1 , wherein the mold is axially symmetric with respect to the axis of the mold.

3. The mold machining method using an end mill according to claim 1 , wherein a ratio of similitude of the contour of the second area to the contour of the first area is 70 to 85%.

4. The mold machining method using an end mill according to claim 1 , wherein a ratio of contour length of the first area to contour length of an area corresponding to an optical surface of a lens manufactured by the mold is 50% or greater.

5. The mold machining method using an end mill according to claim 1 , wherein a value of radius of curvature of the contour of the second area is determined such that the value does not exceed 2.5 millimeters.

Assignees

• Nalux Co Ltd

Inventors

• Nishio Yukinobu

Classifications

• B23C2220/52

  Orbital drilling, i.e. use of a milling cutter moved in a spiral path to produce a hole · CPC title

• Y10T409/303808

  including infeeding · CPC title

• B23C2270/18

  Milling internal areas of components · CPC title

• Y10T409/307616

  with means to move cutter eccentrically · CPC title

• Y10T409/304424

  Means for internal milling · CPC title