Lens surfacing pad

A cutaway pad for surfacing lenses with grinding or polishing slurries which flow into and along the cuts for distribution across a lens surface worked thereover. The heretofore pad floppiness is relieved with a continuous film backing which is readily conformable to a surfacing tool face and affords large area contact to prevent pad slippage during lens surfacing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
Lens surfacing equipment with particular reference to improvements in 
grinding and polishing pads. 
2. Discussion of the Prior Art: 
Lens grinding and polishing pads are commonly cut away to provide channels 
for distributing abrasive slurries over the surface of a lens to be 
worked. The cuts are usually radially oriented with many or all extending 
from near the center to the edge of the pad. This produces floppy pad 
segments rendering the pads difficult to handle and particularly difficult 
to attach to surfacing tools with their segments properly aligned and 
similarly difficult to remove for replacement. 
With the usual adhesive backings of the floppy cutaways tending to 
accidentally stick to one another and to the hands or unwanted areas of a 
tool surface, a considerable waste of time and frustration can be 
experienced in initially applying the pad to a surfacing tool and/or 
replacing same, not to mention the costliness of machine downtime during 
pad installation or replacement. Pad slippage and wrinkling due to loss of 
tool contact in cutaway areas of prior art pads have also been detrimental 
to lens product yield and quality. 
An object of the invention is to overcome the problems of difficult 
surfacing pad handling and more particularly provide for greater than 
usual ease of cutaway pad application to supporting tools and their 
replacement, all with an assurance of proper working alignment of pad 
segments and secureness of their attachment to the tools. Another object 
is to provide for simple one piece removal of spent pads. 
Other objects and advantages of the invention will become apparent from the 
following description. 
SUMMARY OF THE INVENTION 
The foregoing object and others that may follow are accomplished with the 
provision of thin film backings for cutaway lens surfacing pads which 
permanently support and maintain the desired orientation of pad segments 
and cut channels. The film, in each case, is backed with a pressure 
sensitive adhesive for selectively attaching the pad to a surfacing tool. 
With the adhesive-backed film forming an uninterrupted surface attachment 
to the tool, pad slippage is avoided during lens working and proper 
alignment of pad segments is maintained for optimum flow of abrasive 
slurries along the cutaways. 
Details of the invention will become more readily apparent from the 
following description when taken in conjunction with the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, apparatus 10 of FIG. 1 is exemplary of means 
used to surface (e.g., fine grind or polish) lenses with abrasive 
slurries. A blocked lens L is oscillated over a woven, felted or flocked 
pad 12 mounted upon a surfacing tool 14. The tool is provided with a 
surface 16 having a shape corresponding to that desired to be worked and 
pad 12 is adhesively attached to the tool surface 16. The tool surface 
which receives pads 12 may be formed of a wire mesh in which case pad 12 
would be placed directly upon the wire mesh. 
Tool 14 is supported by carrier 18 which may be rotated or held stationary 
if desired. Those interested in details of the operation of apparatus such 
as the above may refer to U.S. Pat. No. 3,916,574. 
The felted, flocked or woven surfacing pad 12 normally has a pressure 
sensitive adhesive backing 20 for attachment to tool 14 or is placed 
directly upon the aforesaid wire mesh surface without adhesive backing 20. 
It is, in either case, typically cut away to provide radial channels for 
conducting abrasive slurries toward and away from the center of the pad, 
i.e. for distribution of the abrasive over the surface of a lens L being 
worked. Pad 12A (FIG. 2) having channels 22 is exemplary of a commonly 
used cutaway configuration. 
Heretofore, however, the cutaways which form channels 22 have left the pad 
with floppy sections 24 (FIG. 2) which, with adhesive backings exposed, 
become difficult to handle. There is the tendency for the floppy sections 
to stick together, to the hands and/or to unwanted areas of a tool surface 
16 intended to receive the pad and further become difficult to remove when 
replacement is necessary. 
In overcoming the frustration experienced in handling such pads and 
particularly with a view to avoiding pad slippage during use and the 
heretofore undue machine down-time resulting from tedious pad replacement, 
pad 12 (FIGS. 1 and 3) of the present invention is designed to permanently 
maintain a predetermine alignment of sections 24 and afford a greater than 
usual area of adhesive contact with the surface of a receiving tool. To 
this end the felted, flocked or fabric component 26 of pad 12 having the 
usual cutaway channels 22 is backed with a thin and flexible film 28, 
itself having a backing 30 of pressure sensitive adhesive and a strip-away 
protective cover 31. When intended for use over a wire mesh surface, the 
pressure sensitive adhesive may be omitted. 
The cutaway pad component 26 is secured to film 28 with a suitable layer of 
adhesive 32 which holds the original precut geometrical shape and 
orientation of sections 24 during storage and use of the pad 12. 
Suitable materials for film 28 are a rubber-resin adhesive on thin paper or 
on a polyester film. An example of the former is a double faced adhesive 
product of Minnesota Mining and Manufacturing Company, St. Paul, 
Minnesota, USA. This product is identified as 410 DSL. An example of the 
latter is a product of the same company having the commercial 
identification Y443. A useful single faced adhesive tape product also 
supplied by the above company is commercially identified as Surface Saver 
Tape. 
Other films, tapes and adhesives known to be capable of performing the 
above functions may be used at the discretion of the artisan. 
With pad 12 secured to tool 14 as illustrated in FIG. 5, film 28 and 
sections 24 of pad component 26 readily assume the particular 
configuration of the tool surface 16 leaving all channels 22 open adjacent 
their edges to permit an in-and-out flow of an abrasive slurry 32 as 
indicated by arrows 33. This enchances the working of the surface of lens 
L when pressed against pad 12 and oscillated thereover. Sections 24 of the 
pad component 26 are retained in their intended geometrical positions on 
tool 14 so that channels 22 do not become closed or excessively open by 
prior pad shifting, i.e. the full surface contact of film 28 over tool 
surface 16 prevents pad slippage and wrinkling. Pads 12 (FIGS. 3-5) 
applied to tool surfaces 16 of strong dioptric curvature may effect some 
tucking of film 28 in channels 22, all of which will take place below the 
effective abrading surface of sections 24 and only to an extent of 
occupying a small portion of the width of any one channel 22 so that the 
flow of abrasive slurries in channels 22 is, for all practical purposes, 
unaffected by the degree of curvature of tool surfaces 16 to which the 
present surfacing pads may be attached. 
The foregoing illustrates the present objectives of affording greater than 
usual ease of cutaway pad application to tools and optimum secureness of 
their attachment. Additionally, the invention permits greater than usual 
relief (cutaway) of surfacing pads for improved lens surface abrading 
action. All pad sections such as 24, in all cases, are held in desired 
positions prior to and during use by film backings 28. The section 24 may 
be of various shapes and sizes and completely segmented, if desired. For 
example, sections 24 may be square or otherwise rectilinear and arranged 
in checker-board fashion on film 28. 
FIG. 6 illustrates another modification of a cutaway surfacing pad having 
film backing 28a, channels 22a extending inwardly from the edge of the pad 
and channels 22b extending outwardly from the center of the pad. 
Use of the term "film" hereinabove is intended to include such thin and 
flexible sheet materials as paper and cloth as well as plastic materials. 
Also, the term "lens" is intended to include the ophthalmic product in any 
of its various stages of manufacturing, e.g. cast, molded, pressed and/or 
machined whether formed of glass, a resin or another form of plastic 
material. 
It will become readily apparent to those skilled in the art that there may 
be modifications and other adaptations of the precise form of the 
invention shown and described. Accordingly, the foregoing illustrations 
are not to be interpreted as restrictive of the invention beyond that is 
necessitated by the following claims.