Lens surfacing tool and tool holder
LENS SURFACING TOOL AND TOOL HOLDER 
     1. Field of the Invention 
     Ophthalmic lens surfacing apparatus with particular reference to improvements in surfacing tool and tool adaptor system. 
     2. Discussion of the Prior Art 
     Blocked ophthalmic lenses having semi-finished surfaces requiring final precision grinding and polishing are traditionally pressed against preformed tools (laps) and oscillated thereover while a grinding or polishing slurry is applied to the lens-tool interface. 
     In toric lens surfacing where the right-angular relationships of cylinder and spherical curvatures must be preserved, the surfacing tool is prevented from rotating upon the tool holder and, as it is well known, lens harnessing means maintains proper cylinder orientation during the oscillation. U.S. Pat. No. 3,916,547 is exemplary. In preventing rotation of the surfacing tool upon its holder with the customary key and key slot, however, there is the serious drawback of tool and adaptor wear causing axial misalignment of the tool relative to the lens surface being abraded and vice versa. 
     Surfacing tools and their holders are subject to considerable wear from the abrading action of surfacing. Relative rotational motion between tool and holder, however slight in new tooling, increases rapidly with tool use in the environement of a grinding slurry. Inclusions of grinding abrasives between the key and key slot cause rapid wear thereof and tool loosening and misalignment. 
     There being the necessity to operate lens surfacing tools in abrasive environments, the present invention has a principal objective of providing improvements in manually assembled lens surfacing tools and holders which render the accuracy of relative centering, decentering and rotational alignment insensitive to wear from the abrading action of surfacing. 
     Another object is to accomplish the foregoing without sacrifice of optimum ease and convenience of manual assembly and disassembly of tool and holder for desired tool interchange; and 
     STILL ANOTHER OBJECT IS TO AFFORD THE OPPORTUNITY TO DECENTER THE TOOL AS DESIRED OR NEEDED TO SUIT PARTICULAR REQUIREMENTS OF LENS SURFACING. 
     Other objects and advantages of the invention will become apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The aforesaid objects and corollaries thereof are accomplished by providing a multiplicity of mating pyramidal protrusions on the lens surfacing tool and its holder. These pyramidal surfaces may be in the form of large knurlings extending across all or portions of the joined, or to be joined, faces of the tool and holder. Fixing the tool against rotational misalignment on its holder and in desired centered or decentered relationship therewith is accomplished by simple manual placement of one against the other. 
     Details of the invention will become more readily apparent from the following description when taken in conjunction with the accompanying drawings: 
    
    
     IN THE DRAWINGS 
     FIG. 1 is a fragmentary partially cross-sectioned illustration of lens surfacing apparatus embodying the invention. 
     FIG. 2 is a fragmentary view of the apparatus of FIG. 1 illustrating a tool decentering feature of the invention. 
     FIGS. 3 and 4 are plan views of mating faces of tool and holder components of the FIG. 1 embodiment of surfacing apparatus; and 
     FIG. 5 is a greatly enlarged fragmentary cross-sectional view taken approximately along line 5--5 of FIG. 4. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The lens surfacing apparatus 10 of FIG. 1 comprises surfacing tool (lap) 12, holder 14 for supporting tool 12 upon spindle 16 and lens harnessing means 18 which is adapted to be oscillated in conventional fashion for moving lens L across surface 20 of tool 12. Lens L is fastened to block B which, in turn, is coupled to harnessing means 18 for maintaining proper relative rotational orientation of the lens and tool. 
     To the extent that apparatus 10 has been thus far described, those interested in greater detail may refer to U.S. Pat. No. 3,916,547. 
     As mentioned hereinabove, the present invention overcomes previous problems of wear from the abrading action of surfacing in the environment of abrasive slurries. To this end, the usual key and key slot connection between tool and tool holder is obviated. Instead, there are provided uniquely designed interfitting tool and tool holder connecting faces which are functionally insensitive to wear, i.e. the secureness of interfitting and accuracy of relative axial and rotational tool and holder alignment are uneffected by wear due to inclusions of loose abrasives. 
     Tool holder 14 (FIGS. 1,2 and 4) having tool supporting face 22 is provided with a uniformly patterned multiplicity of juxtapositioned pyramidal protrusions 24, one of which is illustrated in greatly enlarged cross-section in FIG. 5. As it will become apparent hereinafter, it is preferable to locate the centermost of the multiplicity of protrusions 24 precisely at the center, i.e. on vertical axis x FIG. 1, of tool holder 14. Axis x is illustrated by a dot in the center of FIG. 4. 
     In conjunction with tool supporting face 22 of holder 14, the annular mounting face 26 of tool 12 is provided with matching pyramidal protrusions 28 which are adapted to mate with protrusions 24 upon manual placement of tool 12 against holder 14. It is pointed out that the pyramidal protrusions 28 are so relatively geometrically arranged that they are concentric with center c (FIG. 3) of tool 14 and automatically render tool 12 centered on holder 14 when edges of the tool and holder are aligned. It should be understood that recesses 30 and 32 in tool 12 may be dispensed with should it be desired to extend the illustrated annular mounting face 26 of tool 12 continuously thereacross. Since, however, this is not necessary, the illustrated annular face 26 is presently preferred. It may, nevertheless, be of greater width than illustrated, e.g. by occupying a portion or all of recess 30 and/or extended over a portion of recess 32 as well. 
     In addition to the provision for automatic tool 12 centering by interfitting faces 22 and 26 as illustrated in FIG. 1, the tool may be decentered in increments of the width of one pyramidal protrusion 24 or 28 as illustrated in FIG. 2. 
     In either the case of centering or decentering of tool 12 upon holder 14 the outermost portions of the four right-angularly related guadrants of annular mounting face 26 of tool 14 are provided with ridges 34 and 36. Ridges 34 extend right-angularly to ridges 36 and vice versa. These ridges are continuations of corresponding ideas of pyramidal protrusions 28 and are thus adapted to mate with pyramidal protrusions 24 of holder 14 and prevent longitudinal slippage of tool 12 in any lateral direction relative to holder 14. It should be understood that ridges similar to 34 and 36 (FIG. 3 may be provided upon supporting face 22 of holder 14 if desired, i.e. as extensions of corresponding sides of pyramidal protrusion 24. By such means, ridges 34 and 36 may be eliminated from mounting face 26 of tool 12 so that pyramidal protrusions 28 can be carried from edge-to-edge of face 26. 
     It is contemplated that pyramidal protrusions 24, 28 and ridges 34, 36 be formed on their respective faces 22, 26 by coarse knurling of these faces. Additionally, ends 38 (FIG. 5) of all pyramidal protrusions 24, 28 and grooves 34, 36 are flattened substantially as illustrated. Thus, any wear upon pyramidal protrusions 24, 28 and/or grooves 34, 36 tending to cause their narrowing and/or shortening will merely, in turn, cause deeper fitting of tool face 22 into mounting face 26. The wear being so compensated for renders the accuracy of centering and relative rotational alignment of tool 12 and holder 14 unaffected, i.e. the system of tool 12 and holder 14 is functionally insensitive to wear from the abrading action of surfacing. 
     Those skilled in the art will readily appreciate that there are various other forms and adaptations of the invention which may be made to suit particular requirements. 
     For example, protrusions 24, 28 and/or ridges 34, 36 may be in the form of spaces between recesses formed on one or both of faces 22, 26 of tool 12 and holder 14. Furthermore, the recesses and/or protrusions may be other than pyramidal, i.e. they may be conical or frustums of cones or pyramids or in forms such as grooves and ridges extending radially from points adjacent the centers of faces 22, 26. 
     Accordingly, the foregoing illustrations are not to be interpreted as restrictive of the invention beyond that necessitated by the following claims.