Patent Publication Number: US-4320599-A

Title: Polisher-finer apparatus

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an apparatus for finishing lenses. More specifically, this invention related to an apparatus for polishing or fining toric surfaces of ophthalmic lenses. In ophthalmic lens finishing, the terms &#34;polish&#34; and &#34;fine&#34; are terms of art indicating a degree of finish achieved. Since the subject apparatus is used for both polishing and fining the terms will be used interchangeably. 
     In ophthalmic optics, lens blanks are formed from glass or plastic and a convex surface of the lens is mounted upon a retaining member known as a lens block. The lens and block are then accurately mounted upon a grinding apparatus wherein a torodial surface of compound prescriptive value is rough ground into a concave portion of the lens. In this regard a first principal meridian of the lens typically has a different dimension than a second principal meridian normal to the first. Following the initial grinding operation, an ophthalmic lens is fined and then polished to a final prescriptive value. Left and right lenses are then mounted upon an edge grinding machine to cut the outer peripheral shape required to be compatible with an ultimate wearers eye glass frame. 
     The subject invention is directed to a polisher-finer apparatus and comprises an improvement over a Stith U.S. Pat. No. 3,732,647 of common assignment with the subject application. More specifically, the Stith patent discloses a polisher-finer wherein the lens is finished by being biased into a lapping tool having a toric surface of the final desired prescriptive value. The lapping tool is driven in an orbital, break-up motion relative to the lens to prevent ridges, grooves and/or other aberrations from forming in the lens surface which might occur if regular or uniform motion devices were utilized. In addition to orbital, break-up motion of the lapping tool the Stith patent discloses moving the lens in a transverse motion from side-to-side. In at least one other system, front to rear motion is added to the transverse motion of the lens to be finished. 
     Although polisher-finer systems of the type previously described have been widely utilized, room for significant improvement remains. In this regard, it would be desirable to increase the relative speed of motion between the lapping tool and lens without sacrificing any of the system finishing ability. Still further it would be desirable to be able to facilely vary the amplitude of the orbital, break-up motion of the apparatus. 
     OBJECTS OF THE INVENTION 
     It is therefore a general object of the invention to provide a novel apparatus for finishing ophthalmic lenses which will advantageously achieve desirable characteristics of the type previously described. 
     It is a particular object of the invention to enhance the speed in which toric lens surfaces may be finished. 
     It is a related object of the invention to decrease lens finishing time without increasing the orbital, break-up speed of the lens lapping tool. 
     It is another object of the invention to provide a novel apparatus wherein the amplitude of orbital, break-up motion of a lens finishing apparatus may be facilely adjusted. 
     It is a further object of the invention to provide a novel lens finishing apparatus wherein the relative finishing motion between a lens lapping tool and a lens may be enhanced. 
     BRIEF SUMMARY OF THE INVENTION 
     A preferred embodiment of the invention which is intended to accomplish at least some of the foregoing objects comprises a lens finishing apparatus having a first gimbal mounted assembly for providing an orbital, break-up motion to a lens lapping tool. The subject finishing apparatus further includes a second gimbal mounted assembly for providing an orbital, break-up motion to a lens to be finished. In combination the first and second gimbal mounted assemblies produce a dual orbital, break-up motion between a toric lens and a lapping tool. First and second adjustment assemblies are connected to the first and second gimbal mounted members for selectively varying the amplitude of the orbital, break-up motions. 
    
    
     THE DRAWINGS 
     Other objects and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an axonometric view of an apparatus for finishing ophthalmic lenses in accordance with a preferred embodiment of the invention; 
     FIG. 2 is a front view of the apparatus depicted in FIG. 1 with the front housing elements removed to disclose dual break-up motion assemblies mounted above and below lens to be finished; 
     FIG. 3 is a side elevational view of the subject apparatus wherein one set of upper and lower break-up motion assemblies are particularly illustrated; 
     FIG. 4 is a back view of the apparatus depicted in FIGS. 1-3; 
     FIG. 5 is a top view of the subject apparatus; 
     FIG. 6 is a cross-sectional view taken along section line 6--6 in FIG. 3 and discloses a first eccentric mounting assembly; 
     FIG. 7 is an axonometric view of one form of flexible belt used with the subject apparatus; 
     FIG. 8 is an axonometric view of another form of belt used with the subject apparatus; 
     FIG. 9 is an exploded axonometric view of a second eccentric mounting assembly wherein the eccentricity may be facilely adjusted as desired; 
     FIG. 10 is a schematic cross-sectional view of the adjustable eccentric in one extreme position; and 
     FIG. 11 is a schematic cross-sectional view of the adjustable eccentric, similar to FIG. 10 but in the other extreme position of adjustment. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein like numberal indicate like parts, and particularly FIG. 1 thereof, there will be seen an axonometric view of a polisher-finer apparatus 20 in accordance with a preferred embodiment of the invention. 
     Before providing a detailed description of the subject structural system it may be worthwhile to briefly outline the context of the instant invention. In this connection, the polisher-finer apparatus 20 includes a generally upright frame 22, note FIG. 2, which supports left and right side walls 24 and 26 respectively as well as upper 28 and lower 30 front cabinet members. A working enclosure 32 is mounted at a generally mid point of the apparatus and includes a catch basis 34 and a lid 36 having a transparent window 38. 
     The apparatus is provided with a closed loop fluid system, an air pressure system and an electrical system (not shown). These systems are controlled and monitored by an array of guages and control switches 40 which are within the purview of one skilled in the art. 
     In brief operation, an operator desiring to finish ophthalmic lenses lifts the cover 36 and inserts lapping tools 42 and 44, note FIG. 2, onto left and right orbital, break-up assemblies 46 and 48. The lapping tools are selected to have a convex toric configuration compatible with the shape of the lenses to be finished. 
     Left 50 and right 52 blocked lenses are then positioned upon the lapping surface of the tools 42 and 44 respectively and are biased against the lapping tools by the provision of air pressure biasing assemblies 54 and 56, note FIGS. 2 and 3. The biasing assemblies in turn are suspended by left and right orbital, break-up assemblies 58 and 60. 
     Lens finishing (i.e. polishing and/or fining) is then achieved by producing relative orbital, break-up motion between the lenses 50 and 52 and associated lapping tools 42 and 44 respectively. The working surfaces of the tools are continuously drenched within the working enclosure 32 with a fine abrasive fluid from a closed loop fluidic system as previously mentioned. 
     Dual, Orbital, Break-up Structure 
     Referring now to FIGS. 2-8, there will be seen various detailed views of dual, orbital, break-up assemblies, in accordance with a preferred embodiment of the invention. 
     The orbital, break-up motion assemblies 46 and 48 are mounted upon a lower portion of the frame 22 and are identical in function and structure. Accordingly, only unit 46 will be described in detail with corresponding elements of the unit on the right indicated by the same numeral with the addition of a prime mark. 
     The orbital, break-up assembly 46 includes a first shaft 62 which is journaled through an eccentric bearing assembly 64, note sheet 6, mounted upon frame 22. An electric motor 66 is also connected to a lower portion of the frame and includes a downwardly extending output shaft 68 to which a pair of pulleys 70 and 72 are mounted. A flexible belt 74, note also FIG. 7, connects pulley 70 to a pulley 76 mounted upon the lower end of shaft 62. A similar flexible belt 76 connects pulley 72 to a pulley 78 mounted upon the lower end of shaft 62&#39;. Accordingly, the motor 66 served to rotate shafts 62 and 62&#39; within the eccentric bearings 64 and 64&#39;. 
     The bearings 64 and 74&#39;, as noted in FIG. 6, include a cylindrical eccentric 80. The eccentric is rotated within the bearing assembly 64 by the provision of a second electric motor 82 having a downwardly extending drive shaft and pulley 84 and a synchronous drive belt 86, note FIG. 8, which passes around pulleys 88 and 88&#39; connected to the eccentric. 
     As will be appreciated, the upper ends 90, 90&#39; of the first shafts 62, 62&#39; exhibit a rotational motion about their axes and a circular motion upon the periphery of an imaginery cylinder from the motion of eccentrics 80, 80&#39;. In practice, the shafts 62, 62&#39; are rotated must faster than the eccentrics 80, 80&#39; and in combination impart a dual motion to the upper end of the first shafts 62, 62&#39;. 
     Each orbital, break-up assembly 46 and 48 further includes a second shaft 92, 92&#39; which projects at the uppermost ends thereof into the working enclosure 32 and serves to carry lapping tools 42, 44 respectively having a pre-selected toric curvature. 
     The second shafts 92, 92&#39; extend through generally horizontal gimbal mounting assemblies 96, 96&#39; which are mounted upon a lower portion of frame 22. 
     The lowermost portion of the shafts 92, 92&#39; are fitted with the socket portion 98, 98&#39; of universal ball joints 100, 100&#39;. Adjustment assemblies 102, 102&#39; which will be discussed in detail below, carring balls 104, 104&#39; interconnect the first shafts 62, 62&#39; with the second shafts 92, 92&#39;. The rotational and orbital motion of the first shafts are thus imparted to the second shafts 92, 92&#39; which are prevented from rotation by the gimbal assemblies. The resultant motion of the lapping tools 42 and 44 may be characterized as an orbital break-up motion wherein the primary meridian of the lapping tool toric surface do not rotate. In order to effectuate the foregoing motions it will be appreciated by those skilled in the art that a degree of axial play is built into the connection assemblies and/or an axial slip joint is incorporated into the shafts as desired. 
     As previously indicated left 50 and right 52 blocked lenses are positioned upon the upper surface of the lapping tools 42 and 44. The lenses are continuously biased into engagement with the lapping tools by left and right air cylinder assemblies 54 and 56 respectively. Left 110 and right 112 prongs extend downwardly from each air cylinder assembly and fits into spaced recesses formed within the back surface of the lens blocks. Horizontal arms 114, 114&#39; of the air pressure biasing assemblies 54 and 56 are supported by pivot brackets 116, 116&#39; carried by the left and right orbital, break-up assemblies 58 and 60. 
     Assemblies 58 and 60 comprises elements common with and are similar in structure and function to the orbital, break-up assemblies 46 and 48. Accordingly a detailed description of these assemblies are incorporated by reference by referring again to the description of assemblies 46 and 48. Briefly, however, assemblies 58 and 60 include first generally vertical shafts 118, 118&#39; which are journaled through eccentric bearing assemblies 120, 120&#39; such as previously illustrated in connection with FIG. 6. 
     An electric motor 122 drives shafts 118, 118&#39; while electric motor 124 drives eccentrics 126, 126&#39; to produce a resultant rotational and orbital motion to the lower end of shafts 118, 118&#39;. The assemblies 58 and 60 also include second shafts 128, 128&#39; which extend through gimbal mounting assemblies 130, 130&#39;. The first and second shafts are interconnected through amplitude adjustment assemblies 132, 132&#39; and ball joint assemblies 134, 134&#39; in a manner previously discussed in connection with orbital break-up assemblies 46 and 48. 
     In accordance with the foregoing, pivot brackets 116, 116&#39; and accordingly lenses 50 and 52 will exhibit an orbital, break-up motion relative to the lapping tools wherein the base and cross curves do not rotate but remain parallel with the base curve and cross curve of the lapping tool during the entire lens finishing operation. 
     Adjustment Mechanism 
     Referring now to FIGS. 9-11 there will be seen an eccentric adjustment assembly 102 for adjusting the amphitude of orbital, break-up motion of the unit apparatus in accordance with a preferred embodiment of the invention. 
     More specifically, the adjustment member includes a base member 140 comprising a generally solid cylindrical member having a radially enlarged head portion 142 at one end thereof. The other end 144 of the cylindrical member fits securely within a mounting ring 146 which may be fixedly connected to the free end of shaft 62, note FIGS. 2 and 3. Accordingly, the cylindrical base member 140 will follow the rotating orbital motion of the shaft 62. 
     The free end of the radially enlarged head portion 142 is fashioned with a cylindrical recess 148 having a central longitudinal axis 150 which is radially offset from the central longitudinal axis 152 of the base member 140. An eccentric member 154 comprising a generally solid cylindrical plug is dimensioned to be coaxially received within recess 148. An upper surface of the eccentric member 154 has a threaded recess 158 to receive a threaded mounting for a ball 104 of a universal ball joint 100, note FIG. 3. As can be seen in FIGS. 10 and 11, the ball mounting recess 158 is radially offset from the central pivotal axis of the eccentric 154 such that rotation of said eccentric will serve to vary the distance the ball mounting is offset with respect to the central longitudinal axis 152 of the base member; compare the distance of offset A in FIG. 10 with the distance of offset B in FIG. 11. 
     Adjustment of the offset distance is achieved by the present invention through the provision of a radially opening window 160 and an adjustment arm 162 which projects through the window and screws into the eccentric 154. 
     In order to initially secure the adjustment arm 162 in a given position a retaining collar 164, having a plurality of slots 166 in a longitudinal rim thereof, is mounted about the base member 140. Mounting is achieved by a plurality of threaded rods 168 which extend through corresponding longitudinal slots 170 in the collar 164. The rods 168 thread into corresponding radial openings, such as 172, in the base member 140 and thus permit the retaining collar 164 to axially slide along the collar while relative rotation is prevented. 
     The inner periphery of the collar is fashioned with a radial stop ledge 174 which operably abuts against the enlarged head portion 142 of the base member. 
     The stop ledge 174 of the retaining collar 164 is normally biased against the head portion 142 by the provision of axially extending compression springs 176. In this posture a notch 166 of the retaining ring will fit around the adjustment arm 162 to maintain the eccentric 154 in a desired position. 
     When it is desirable to adjust the position of the eccentric and thus the amplitude of the orbital, break-up motion of the apparatus, the collar 164 is depressed against the compression springs 176 and the arm 162 is rotated to a desired position. The retaining ring is then released and a slot 166 re-engages the adjustment arm; compare the position of adjustment arm 162 in FIGS. 10 and 11. In order to gauge the degree of adjustment a second collar 180 is mounted about the upper end of collar 164 and is imprinted with numerical indicia 182 corresponding to slot, and thus adjustment, locations on the retaining collar 164. 
     In order to tightly secure the eccentric 154 in a position of adjustment, in addition to arm 162 and collar 164, the head portion 142 of the base member 140 is fashioned with a threaded aperature 184 which radially intersects axis 150. The eccentric is fashioned with a peripheral recess 186 and a set screw 188 extends through the aperature to releasably engage the recess 186 and retain the eccentric in a desired position of adjustment. 
     In the event it is desired to increase or decrease the amphitude of the units orbital, breakup motion, by offsetting the ball 104 with respect to the central, longitudinal axis of the base 140, the set screw 188 is backed off and the collar 164 depressed against compression springs 176. The adjustment arm 162 is then rotated to a desired numercial station and the retaining collar 164 is released whereby a notch 166 re-engages the adjustment arm 162. The set screw is then tightened down and the adjustment is completed. 
     ADVANTAGES OF THE INVENTION 
     After reviewing the foregoing description of a preferred embodiment of the invention, in conjunction with the drawings, it will be appreciated by those skilled in the art that several distinct advantages of the subject polisher-finer apparatus are obtained. 
     Without attempting to set forth all of the desirable features of the instant invention, at least some of the major advantages include the unique orbital, break-up motion of both the lapping tool and the lens being finished. 
     The dual, orbital, break-up motion enhances the relative movement between the lens and lapping tool to increase the speed of the lens finishing operation without imparting a regular or uniform motion factor which might tend to permit fine ridges, grooves or the like to form during the finishing process. 
     The adjustment assembly permits the ball of the universal ball joint unit to be selectively offset to facilely adjust the amphitude of the orbital, break-up motion of the lapping tool and lens. 
     In describing the invention, reference has been made to a preferred embodiment. Those skilled in the art, however, and familiar with the disclosure of the subject invention, may recognize additions, deletions, modifications, substitutions and/or other changes which will fall within the purview of the subject invention.