Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1999-04-29
2002-01-01
Grant, Willaim (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C451S005000, C451S043000
Reexamination Certificate
active
06336057
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an eyeglass lens grinding apparatus for grinding the periphery of an eyeglass lens.
An eyeglass lens grinding apparatus is known which grinds the periphery of an eyeglass lens so that the eyeglass lens fits into an eyeglass frame. In this type of apparatus, a lens to be processed is mounted on one lens rotating shaft via a mounting jig such as a suction cup fixed to a front surface of the lens, while a rear surface of the lens is pressed by a lens holder of another lens rotating shaft, thereby clamping or chucking the lens using the two lens rotating shafts for processing.
In general, a chamfering process is performed subsequently to the peripheral processing so as to remove sharp corner portions from peripheral edges of the lens. Conventionally, this chamfering process is effected manually using a so-called hand grinder having a conical grinding wheel after the lens subjected to a finishing process is detached from the grinding apparatus. However, this operation requires expert skill and is not easy to perform.
Accordingly, the present applicant or assignee proposed an apparatus which makes it possible to perform the chamfering process efficiently with a simple arrangement, as disclosed in Japanese Unexamined Patent Publication No. 254000/1997 and U.S. Pat. No. 5,803,793. The apparatus has a grinding-wheel rotating shaft on which a chamfering grinding wheel and other processing grinding wheels are disposed coaxially. The apparatus controls the relative movement of the grinding-wheel rotating shaft with respect to the lens rotating shaft as well as the axial movement of the grinding-wheel rotating shaft on the basis of chamfering process data, to thereby perform the chamfering process of the lens front and rear surfaces without dismounting the lens subjected to the finishing process from the lens rotating shaft. The chamfering process data is obtained by measuring edge positions on the front and rear surfaces of the lens on the basis of radius vector data on the eyeglass frame and on the basis of the result of that measurement.
However, if the lens to be processed is clamped by the lens rotating shafts, the lens is deflected (deformed) depending on the shape of its front surface side. Generally, if the curve of the lens front surface is gentle with respect to the shape of the lens receiving surface of a mounting jig (in the case of a minus lens), the lens is deformed toward its rear surface side due to a pressing force of the lens holder. In contrast, in a case where the curve of the lens front surface is sharp (in the case of a plus lens), the lens is deformed toward its front surface side. In the case of an unprocessed lens, the stress of this deformation is applied to the overall lens, and is therefore small. If the lens is made smaller by rough grinding, however, since the portion for absorbing the stress is reduced, the deformation is enlarged. The smaller power the lens, that is, smaller the lens thickness becomes, the greater the deformation. The difference of deformation amount before and after rough grinding can reach about 0.2 mm at maximum. For this reason, if the chamfering process is performed on the basis of the lens shape data measured before rough grinding, there are cases where the actual amount of chamfering will differs from an intended amount of chamfering, and the chamfering will not be uniform visually.
SUMMARY OF THE INVENTION
In view of the above-described problems, it is an object of the present invention to provide an apparatus which makes it possible to perform the chamfering process (the processing of edge corner portions) with high accuracy.
The present invention provides the followings:
(1) An eyeglass lens grinding apparatus for grinding a periphery of a lens, comprising:
a lens holding system which holds a lens while clamping the lens;
a data input system which inputs shape data of an eyeglass frame to which the lens is fitted, and layout data of the lens with respect to the eyeglass frame;
an edge-position-data calculating system which, on the basis of the data inputted by the data input system, obtains edge position data of the lens after layout;
a first measuring system which measures an edge position of the lens before processing that is held by the lens holding system, on the basis of the edge position data obtained by the edge-position-data calculating system;
a second measuring system which measures an edge position of the lens after rough grinding, on the basis of the edge position data;
a chamfering-process-data calculating system which obtains chamfering process data for processing a corner portion of an edge of the lens after finish processing, on the basis of a result of measurement by the second measuring system;
a chamfering process system having a chamfering grinding wheel, which processes the corner portion of the edge of the lens after the finish processing; and
a chamfering-process controlling system which controls the chamfering process system on the basis of the chamfering process data obtained by the chamfering-process-data calculating system.
(2) The eyeglass lens grinding apparatus according to (1), wherein the edge position data obtained by the edge-position-data calculating system are radius vector data including a radius vector angle and a radius vector length of the lens.
(3) The eyeglass lens grinding apparatus according to (1), further comprising:
a determining system which determines whether or not the lens can be processed on the basis of a result of measurement by the first measuring system; and
a notifying system which notifies a result of determination by the determining system.
(4) The eyeglass lens grinding apparatus according to (1), further comprising:
a storage system which stores an inclination angle of a finishing grinding wheel; and
an information inputting system which inputs information on a positional change in at least one of a lens front surface and a lens rear surface with respect to the edge position data,
wherein the chamfering-process-data calculating system obtains the chamfering process data on the basis of the edge position obtained by the second measuring system, the information on a positional change inputted by the information inputting system, and the inclination angle stored in the storage system.
(5) The eyeglass lens grinding apparatus according to (4), wherein the information on a positional change is information obtained by measuring an edge position different from the edge position measured by the second measuring system on the basis of the edge position data.
(6) The eyeglass lens grinding apparatus according to (5), further comprising:
a position calculating system which calculates, on the basis of the edge position data, another edge position different from the edge position that is measured by the second measuring system on the basis of the edge position data,
wherein the second measuring system also measures the edge position obtained by the position calculating system.
(7) The eyeglass lens grinding apparatus according to (1), further comprising:
a beveling process system having a beveling grinding wheel for such a finishing operation as to form a bevel in the lens after rough grinding;
a beveling-process-data calculating system which obtains beveling process data for forming the bevel in the edge of the lens after rough grinding, on the basis of the result of measurement by the second measuring system; and
a beveling-process controlling system which controls the beveling process system on the basis of the beveling process data obtained by the bevel-process-data calculating system.
(8) The eyeglass lens grinding apparatus according to (7), further comprising:
a storage system which storing an inclination angle of the beveling grinding wheel; and
an information inputting system which inputs information on a positional change in at least one of a lens front surface and a lens rear surface with respect to the edge position data,
wherein the beveling-process-data calculating system obtains the beveling process data on t
Frank Elliot
Grant Willaim
Nidek Co. Ltd.
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