US 5,148,637 AGranted

Lens edging system with programmable feed and speed control

AssigneeBausch & Lomb Incorporated

InventorDavid L. Byron

Life of this patent

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Abstract

A computer numerical control machine system for edging lenses controls the rotation and displacement of a lens workpiece with respect to a edging tool in accordance with a lens shape stored in memory. The system continuously translates the lens workpiece axially across the surface of the wheel to uniformly distribute wear across the wheel surface, reducing the need to dress the edging tool. The system compares the lens size with predetermined dimensions and compenates for any difference by automatically adjusting the lens trajectory during the edging of subsequent lens workpieces, permitting the edging tool to wear down without appreciable errors in lens size. The system controls the edging tool speed, the lens rotation rate, the lens axial feed velocity and the grinding force between the lens workpiece and the wheel at each discrete point during the entire lens edging operation to optimize production while preventing overheating of the lens workpiece. The optimum values for these parameters are empirically determined in a preparatory programmed trial and error learning process of the invention.

Claims21

Dependent claims

A lens edging system for shaping an optical lens workpiece having a major surface, said major surface having a boundary of an initial contour bounded by a relatively thin edge of said workpiece, by grinding said edge so as to change said boundary of said major surface to a new boundary corresponding to a predetermined contour, said system comprising:

an edging tool;
holding means for holding said lens workpiece relative to an axis at least approximately normal to at least a portion of said major surface;
memory means for storing data representing a lens edge grinding trajectory with respect to said edging tool, said data comprising a succession of lens rotation angles about said axis and a succession of lens radii corresponding to said succession of lens rotation angles, said lens radii defining said new boundary with respect to said axis;
servo means for effecting rotation of said lens workpiece relative to said edging tool through servoed lens rotation angles about said axis and motion of the edge of said lens workpiece relative to and toward said edging tool to servoed lens radii;
processor means connected to said memory means for controlling said servo means and for governing said servoed lens radii and said servoed lens rotation angles in accordance with said data, whereby said servoed lens rotation angles correspond to said succession of lens rotation angles stored in said memory and said servoed lens radii correspond to said succession of lens radii stored in said memory, whereby to change the contour of said major surface from said initial contour to said predetermined contour.

2 more elements

A method of operating a lens edging system which controls the movement of a lens workpiece with respect to an edging tool, said lens workpiece having a major surface with a boundary of an initial contour bounded by a relatively thin edge of said workpiece, by grinding said edge so as to change said boundary of said major surface to a new boundary corresponding to a predetermined contour, said method comprising:

storing in said memory data representing a succession of lens rotation angles about an axis at least approximately normal to at least a portion of said major surface and a corresponding succession of lens radii, said lens radii defining said new boundary with respect to said axis;
fetching said succession of radii and said succession of rotation angles from said memory;
holding the edge of said lens workpiece against said edging tool so as to reduce said lens workpiece to the succession of radii fetched from said memory while effecting rotation relative to said edging tool of said lens workpiece to the corresponding succession of rotation angles fetched from said memory, whereby to change the contour of said major surface from said initial contour to said predetermined contour comparing the radius of said lens at a predetermined lens rotation angle to the correct radius and calculating an error therefrom;
and reducing each one of said succession of radii in said memory by the magnitude of said error before edging a subsequent lens workpiece.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 07/803,711Filed 4 Dec 1991 · continuation
Priority: 27 Feb 1990
Granted: 22 Sep 1992
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G05B 19/184
Characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control: generation of cam-like surfaces
B24B 9/148
Of optical work, e.g. lenses, prisms: electrically, e.g. numerically, controlled
B24B 49/02
Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring…
G05B
Control or regulating systems in general