US2737759A - Machines for generating curved surfaces - Google Patents

Description

March 13, 1956 E. M. LONG El' AL MACHINES FOR GENERATING CURVED SURFACES Filed Nov. 15, 1954 2 Sheets-Sheet l March 13, 1956 E. M. LONG ETAL 2,737,759

MACHINES FOR GENERATING CURVED SURFACES United States Patent o MACHINES non GENERATING CURVED sUnFAcEs Application November 15, 1954, serial No. 468,664

8 Claims. (61.51-96) The present invention relates to machines for generating curved surfaces, and more particularly to machines for generating torio surfaces on ophthalmic'lenses by grinding.

It has heretofore been diiiicult to devise 'a light and cheaply constructed machine for generating toric lenses, particularly where the machine must be easily and quickly adjustable for grinding accurate toric surfaces over a wide range of curves.V The known machines of this character are heavy and cumbersome and expensive to manufacture due to the number of slidespivoted parts, heavy bearings, and adjustment regulating devices required to obtain the proper range of curves ofdiferent radii with the necessary accuracy.

The primary object of the invention is to provide an easily and quickly adjustable machine for accuratelyf generating curved surfaces over a considerable' rangeV of radii, which is also light but strong, and simple and economical in construction. While the particular embodiments -of the invention hereinafter described andfshown in the drawings are machines for grinding toric'lenses, it will be apparent that the combination of-parts` employed may be used in any machine in which the work is to bei swung past a generating tool, or the tooll is tobeswungpast the work, in a selected one of a number ofcircular arcs.

Other objects and advantages fof the invention will be apparent from the following description taken in'conneo tion with the accompanying drawings,` inwhich:

Figure 1 is a front elevational view of'a machine for grinding concave toric lenses;

Figure 2 is a fragmentary 'side elevational View thereof;

Figure 3 is a sectional View on the line 3`3 lof-Figure l;

Figure 4 is a plan view of the Vmachine of Figure 1, certain parts being broken away;

Figure 5 is an enlarged sectional View on the line 5*S of Figure 3;

Figure 6 is an enlarged sectional view on the line V6 6 of Figure l;

Figure 7 is a rear View of the machine of Figure l;

Figure 8 is a front elevational view of a machine for grinding convex toric lenses;

Figure 9 is a fragmentary" side elevational View thereof;

Figure 1() is a sectional View on the line lll-10 of Figure 8;

Figure l1 is a top plan'view of the 8, certain parts being broken away;

Figure 12 is an enlarged sectional View on the 'line 1li-12 of Figure 10;

Figure 13 is a sectional view`on the line 13-13 of Figure 12; and

Figure 14 is a rear view of the machine of Figure 8.

Referring more particularly to Figures 1 to 7 ofthe drawings, the machine illustrated therein is adapted for generating concave `toric lens surfaces byv the known method involving swingingalens blank pasta cup-shaped machine of Figure Patented Mar. 13, -1956 grinding wheel rotating about a fixed axis inclined to the axis of swing. In general, the machine 20 comprises a stationary, vertical frame member 21 and a swingable member 22 supported indirectly thereby, one of which members carries the generating tool and the other the work holder and work. Since, in the present instance, the tool is substantially heavier than the work, it is preferable to mount the grinding wheel 23 on the frame member 21 and the lens holder 24 on the swing membery 22. The weight of the swing member 22, lens holder 24 and associated parts is borne by the thin, Aiiexible tension member 25, which may be a steel ribbon or tape, and which is suspended at its upper end from the frame member 21 andV is secured at its lower end to the swing member 22. A rack 26 is vertically adjustable with respect to the frame 21 by means of a pinion 27 rotatable by handwheel 28. The rack 26 carries at its lower end a slide block 29 adapted to operate in a slideway 3i) on the frame member 21. A similar slideway 31 on the swing member 22 is adapted to overlap the slideway 35 and carries a slide block 32 which serves as a bearing for a pivot pin 33' threadedly secured to the slide block 29. Hence the pivot pin 33 is slidable with respect to the members 21 and 22 along the slideways 3' and 31 as the rack 26 is adjusted by turning the. handwheel 28. In addition to the pivot pin 33, the slide block 29 carries two fulcrum pins 34, and the axes of all three pins are parallel and located in the same plane. The two fulcrum pins 34 lie closely adjacent the steel tape 25 at either side thereof, and are preferably in the form of rollers which roll along the tape as the rack 26 is adjusted, and have line contact therewith. The axis of pivot' pin 33 is the axis of swing of the swing member 22 and lies between the lines of contact of the fulcrum rollers 34, which latter define the bending center of the tape 25. Hence as the swing memberoscillates about the pivot pin 33, the tape 25 acts like a pendulum rod having an axis of osciliation coincident with the axis of pin 33.

The machine 12) illustrated in Figures 8 to l-l is adapted for grinding convex torio lenssurfaces. The machine 129 embodies exactly the same principles as the machine 2i), and the parts of Figures 8 to 14 corresponding to those enumerated above for machine 2i) are given corresponding reference numerals just higher.

Turning again to the concave toric generator' Zi?, the vertical frame member 21 has a horizontal supporting flange'36 adapted to be bolted toa Asuitable table or bench, not shown. A tool supporting plate 3'7 serves to support the' grinding Wheel 23 and associated parts as hereinafter described, and is bolted to the frame member 2l in spaced relation thereto through the medium of legs 38 at either side. The swing member 22 is thus enabied to swing freely in the space 39 (Figure 4) between the frame member 21 and plate 37.

The 'front face 41 of framemem'ber 2l and the rear face 42 ofswing member 22 are both machined iiat, and serve as bearing or guide surfaces during the oscillations of the swing member. The machined faces 41 'and 42 are 'held in abutting, sliding relationship partly by the pivot pin 33 and partly by the connector pin e3, which is threaded into the swing member 22 at 4d (Figure 6). The connector pin 43 extends freely through a slot #i5 in therframe member 21 and serves to connect the swing member-22 to the lower end of the steel tape 25. For this purpose, a block 46 is secured to the rear end of pin -43 by a set screw 47, and the tape 25 is fastened to the block 46 by means of a clamping plate 48 and screw 49 (Figures 6, 7).

`The connector pin 43 also serves as a means for connecting an oscillating drive mechanism to the swing member 22. Tor that end,`a" connecting rod Si) is' pivotally mounted on the pin 43 between the frame member 21 and block 46, and is provided with a rack 51 at its outer end (Figures 1, 7). Rack 51 is held in mesh with a pinion 52 by a yoke 53 which straddles the pinion and is loosely mounted on the pinion shaft 54 (Figure 2). The shaft 54 is journaled in an arm 55 projecting from the plate 37, and may be rotated by either a handwheel 56 or a gear 57 secured, respectively, to either end of shaft 54. By turning the handwheel 56 first in one direction and then the other, the swing member 22 may be oscillated about the pivot pin 33. If desired, the swing member 22 may be oscillated automatically by means not shown, such as an electric motor controlled by an automatic reversing switch and connected through suitable reduction gearing to the gear S7.

The rear surface of frame member 21 adjacent the slot and the mating surfaces of connecting rod 59 and block 46 should of course be smoothly finished, so that the parts may move freely while serving to hold frame member 21 and swing member 22 together with a sliding fit. is preferably curved as shown in Figure 5, its lower edge being an arc with radius slightly greater than the longest radius of swing within the range of the machine, and its upper edge being an arc with radius slightly less than the shortest radius of swing within that range.

The upper end of steel tape 25 may be secured by means of a clamping plate and screw to a C-shaped support 60 which is suspended from a projecting portion 61 of the frame member 21, preferably by means of a fulcrurn screw 62. By turning the screw 62, the swing member 22 and its associated parts may be bodily raised or lowered a small amount, thereby permitting the vertical position of the center of connector pin 43 to be adjusted for a purpose to be later described.

The slideways 39 and 31 may conveniently be in the form of grooves with upper and lower closed ends (Figures 5, 7), and their central portions may be cut away to form slots and 66, respectively. These slots accommodate the pivot pin 33 and its bearing (formed as part of the slide block 32), and the slot 65 is extended to the upper end of the frame member 21 to permit it to serve as a guideway for thc rack 26. The rack 26 and its pinion 27 are accommodated in a recess at the bottom of the above-mentioned frame projection 61 (Figure 6), and the pinion shaft 67 is journaled in projection 61 and in a cylindrical boss 68 (Figures 1, 3, 7) extending from the side thereof. A thumb screw 69 threaded into boss 68 (Figures l, 3) permits the shaft 67 and its handwheel 23 to be locked in a desired position of adjustment of the pinion 27 and rack 26. 28 of course determines the vertical position of the pvot pin 33 and the associated fulcrum pins or rollers 34. The rollers 34 are rotatably mounted on studs 7 t) screwed into the slide block 29 and maintained in correct alignment by the spacer plate 71.

A bar 73 screwed to the front of fratrie member 21 (Figures l, 5) assists in retaining the rack 26 in slot 65, and also carries an index mark 74 cooperating with a scale 75 on the rack. The scale 75 is preferably graduated in diopters and measures the distance between the centers of pivot pin 33 and connector pin 43. The index 74 and scale 75 may be properly correlated or zeroed in by adjusting screw 62 to vary the position of connector pin 43 as above described.

A trough 78 is fixed to the lower end of swing member 22 and accommodates the work holder 24 which is adjustable longitudinally of the trough and swing member by means of a screw St? and handwheel 81. The trough 78 may be provided with the usual means (not shown) for circulating liquid coolant or the like. The holder 24 is adapted to hold a conventional lens block 82 to which a lens blank 83 may be adhesively secured in customary manner. Adjustment of the handwheel 81 moves the lens blank 83 toward or away from the grinding wheel 23 and permits regulation of the thickness of the finished Slot 45 The adjustment of handwheel lens as later described. The axis of screw is parallel to machined face 42 of swing member 22. As is customary, the lens blank 83 should be so mounted on the lens block 82, and the latter should be so held in the holder 24, that the axes of the lens and of the grinding wheel 23 lie in a common plane perpendicular to the axis of swing (the axis of pivot pin 33), and hence parallel to face 42.

We may now turn to the means for supporting and adjusting the grinding wheel 23. The front face of tool supporting plate 37 has a vertically extending dovetail groove 85 (Figure 4) in which is slidably mounted a tongue on the back of a vertical slide 86. The front of slide 86 is formed with a raised quadrant 37 having an arcuate groove 88, which is T-shaped in cross-section. A tool base 89 is pivoted to the quadrant 87 at 90 (Figure 6), and is provided with a locking lug 91 adapted to slide in the groove 88 and to be locked therein at a desired position of adjustment by a handle 92, in well-known manner.

The tool base 89 has a dovetail groove 93 in which is slidably mounted a tool post 94, which may be locked in the desired position in conventional manner. A tool shaft is journaled in the tool post 94 parallel to the flat bearing surfaces 41 and 42. The shaft 95 carries at one end the cup-shaped grinding wheel 23, and is driven by a motor 96 bolted to the other end of the tool post 94 and connected to an electric power source by a flexible cable 97. A suitable scale, not shown, may be placed near the curved edge of quadrant 87, so that the angular setting of tool shaft 95 may be read off the scale.

The vertical slide 86 may be bodily raised or lowered, carrying with it the quadrant 87 and grinding wheel 23, by turning a handwheel 98 in the appropriate direction. The handwheel 98 has a shaft 99 journaled in bosses 1GO formed on arm 55 of plate 37, which shaft carries a spiral gear 101 meshing with a spiral gear 102 (Figures l, 2). A spool 103 is secured to the spiral gear 102 to rotate therewith, and both are mounted on a vertical shaft 104 fastened to the arm 55. The upper end of shaft 134 is threaded and cooperates with threads in spool 1173, so that spool 103 and gear 102 rise or fall as they turn about shaft 104 in one direction or the other. A lever 105 is pivoted at its center to the plate 37 (Figure 1), and has a block 106 pivoted to each of its ends. Looking toward the front of the machine (Figure l), the right hand block 106 is retained within the rims of spool 193 (Figure 2), and hence the left hand end of lever is lowered as spool 103 is raised, and vice versa. The left hand block 106 is retained within a recess at the back of an extension 107 at the upper end of slide 86, and hence serves to raise or lower the slide as it goes up or down.

Scale 11i) and pointer 111 are provided for indicating thc extent of vertical movement of slide 86 and grinding wheel 23. The scale 110 is fixed to plate 37 and pointer 111 is pivotally secured thereto (Figure l). An arm 112 fastened to the top of vertical slide 86 and projecting sidewise therefrom carries a regulating screw 113 which bears on the lower end of pointer 111, in such manner that the pointer is moved to the right across scale 116 as the slide 86 is lowered. A biasing spring (not shown) urges pointer 111 toward its left hand extreme position and returns it in that direction as vertical slide 86 is raised. The regulating screw 113 should be adjusted so that the pointer 111 reads zero at the right end of scale 119 when the vertical slide 36 is lowered to such position that the axis of tool base pivot 90 is aligned with the center of connector pin 43 when the swing member 22 is vertical. In Figure l, the pointer 111 is shown in the above described zero position, and the corresponding aligned positions of pivot 90 and pin 43 may be seen in Figure 6. The center of connector pin 43 thus affords a common starting point for the measurements made with both scales 75 and 110, as hereinafter described.

While the scale 110 is thus properly zeroed, the grinding wheel 23, tool shaft 95and toolpost 94 should be adjusted relative to each other and to thev tool base 89, so that the arcuate working edge of thev grinding wheel is4 properly aligned with respect to the' axis ofrtool base pivot 9i), and the grinding wheelaxis lies in a yplane perpendicular to the axis of the pivot pin 33-n about which the swing member 22 oscillates. The scale 110 then measures any vertical displacement of grinding wheel 23 from the above-described aligned or reference position. Before the machine is placed in operation, the scales 75 and 11G should be zeroed and the foregoing adjustments made. Thereafter', periodical checks should of course be made to detect and correct for wear or other factors that may have caused mal-adjustment.

The operation of the machine is extremely simple and follows a pattern well-known to those skilled in the art of generating toric lenses. The operator is` usually provided with a lens blank properly aixed `to a lens block andwith instructions regarding the `finishing of the lens and the necessary machine' settings referred to below.

By releasing the handle 92, the tool base 89 maybe swung about its pivot 90 until the grinding wheel-axis has the prescribed angularity tothe vertical, and the handle 92 is then moved to lockedl position. This angular adjustment will not disturb the adjustments-described above as having been made before operation commences, and, together with the wheel size, xes the' cross curve of the toric surface to be generated in known manner. Handwheel 23 may now be turned until scale'75 on rack 26 reads the specified base curve radius.

The operator now raises the ,grinding wheel 23 by turning handwheel 98 until pointer 111 Vswings to a point which indicates on scale 110 the thicknessof glass that it has been determined in the usual manner shall be removed from the lens blank. Having fastened the lens block 82 in 'the holder 24, the operator turns the handwheel 81, with the swing member 22 in vertical position, until the lens blank just contactsv the grinding wheel.

The swing member 22 isthen'swung to one side by turning handwheel 56, and the motor 96 turned on. The grinding wheel 23 is now lowered, by means of handwheel 98, a distance equal to the desiredrdepth of first cut, as indicated by the movement of pointer 111 over scale 110. The swing member 22 is now swung tofthe other side and preferably back again to the side from whichl it started, so that the lens blank passes the rotating grinding wheel in both directions. The grinding wheel 23 is then lowered the desiredv amount for the second cut,` and the grinding passes repeated. Successive cuts'are -made in this manner until pointer 111 reaches'its zero mark, when the final passes are made.

At the conclusion of the foregoing operation, `when the swing member 22 is vertical, thel grindingfwheel will just contact the lens blank while pointer 111 will indicate zero on scale 110. 1n this condition, bothv the axis of tool base pivot 90 and the working edge of grinding wheel 23 are aligned with the center of connector pin 43. Moreover, the distance between the center of connector pin 43 and the axis of pivot pin 33 (which is the same as the distance in diopters shownon scale 75) is the base curve radius, that is to say, the radius of curvature of the upper surface of the lens blank in the direction of swing of the swing member 22. Assuming the tool base 89 was set at the correct angle on the quadrant 87, vthe desired cross curve will have been ground on the lens surface at the same time as the base curve.

Referring now to Figures 8 to 14, the machine 120 there shown is, as already stated, the counterpart of machine with such modifications as are desirableV to adapt machine 120 to grind convex toric lens surfaces. The principal changes are due to the fact that in machine 1211 the lens blank must be located above the axis of swing of the swingrrmember rather vthan below it as in machine 20. The parts numbered from 121 to 134 are 6 identical in general purpose and effect tothe correspondingly numbered parts 21 to 34-of machine-20,' but this direct correspondence ydoes not always exist for higher reference numbers. However, so far'as possible, corresponding reference numerals differing by 160 are used throughout for the two machines.

The vertical'frame member 121 may be bolted to a suitable table or bench, not shown, through the two horizontal supporting flanges 136 at either side of the machine (Figures l0, 14). A substantially rectangular boss 137, integral with frame member 121 at its upper left corner (Figure l2) and located above 'the swing member 122, serves to support the grindingrwheel 123 and associated parts as hereinafter described.

TheV flat, machined faces 141 of frame member 121 and 142 of swing member 122 are held inabutting, sliding relationship not only by the pivot pin 133 -and the connector pin 143, but also bythe drivepin 144. The functions of the connector pin 43 of machine 20am, in effect, divided between the connector pin 143 andidrive pin 144 of machine 120. `The connector pin 143 serves to connect the lower end of swing member 122 to the lowerend of the steel tape below the frame member 121, while the drive pin 144 extends through slot 145 in the frame member and carries, pivotally mounted thereon, the connecting rod having a rack 151 for oscillating the swing member 122 about thepivot pin 133 (Figures 13, 14). Rack 151 is held in mesh with pinion 152 -by a roller 153 mounted onjarm 155 projecting from frame member 121, in which arm pinion shaft 154 is joiurnaled (Figures 8, 9). Pinion shaft 154 may be rotated by a handwheel 156 for oscillating the swing member 122. As before, a gear 157 is provided on the pinion shaft 154 for oscillating the swing member122 automatically if desired.

The upper end of steel tape 125 is secured to one end ofa lever 158 (Figure 14) pivotally mounted on a stud 159 fastened to the back of frame member 121. A regulating screw 162 bearsron the other end of lever 15S, and permits the center of connector pin 143 to be adjusted vertically by a'small amount.

As before, the`slots 165 and 166 (Figures l2, 13)v at the centers of the slideways 130 and 131, respectively, accommodate the pivot pin 133-and itsl bearing (formed aspart of the slide block 132). The rack 126,l pinion 127 andlpinion shaftf167, however, are accommodated in anrextension armj168 bolted tothe rear of frame member 121 at its upper end. (Figures 10,- 13) and provided with a cylindrical boss 168 extending to the left of the machine as viewed from the front (Figures l, 12). HandwheellZS is secured to, pinion shaft-167- at the outer end of boss 168. vA thumb screw- 169 threaded into arm 168 (Figures 10, 12)"permits the rack 126 to be locked in a desired position `of vertical adjustment. The fulcrum lpins or rollers 134 are rotatably mounted on studs 170 screwed into the slide block129 and carried by the angle bracket 172 which is fastened to the bottom of rack-126 (Figures l0, 13). The studs 170 thus serve to connect rack 126 to slide block 129 as well as to rotatably support the rollers 134, whereas the corresponding studs 70 of machine 20 perform only the latter function. The adjustment of handwheel 128 and raek`126 of course determines the vertical positionof pivot pin 133 and the associated rollers 134.

Bar 173, index mark 174 and scale 175 (Figures 8, l2) correspond functionally to. parts 73, 74 and 75 of machine 20, except that scale 175 Vmeasures the distance in diopters between the centers of pivotl pin 133 and drivepin 144. As before, scale 17S may be properly zeroed by adjusting screw 162, since drive pin 144 4is carried by swing member 122 and hence moves with connectorv pin 143 as it is raised or lowered by screw 162 as above described. Also thetrough Y178, work holder 124- and the -associated parts -183 correspondr to the similarly numbered parts of machine 20, but, asV indicated above,

trough 178 is bolted to swing member 122 adjacent its upper end.

A dovetailgroove 185 in boss 137 (Figure 12) accommodates a tongue 186 on the back of quadrant 187 (Figure 1l). From there on, the means for supporting and driving the grinding wheel 123 are practically identical to the corresponding parts of machine 20, and hence detailed description thereof is unnecessary for machine 120. The corresponding parts are numbered according to the scheme previously employed, ending with motor 196.

As before, handwheel 198 operates the means for raising or lowering the quadrant 187 and with it the grinding wheel 123, and this means includes spool 203 threaded on vertical shaft 204 and lever 205. But spool 203 is directly secured to handwheel 198 so that the two rise or fall together as they turn about shaft 204. Shaft 204 is fastened to an arm 200 extending sidewise from the top of frame member 121, and lever 205 is pivoted to an ear 201 projecting upward from the top of frame member 121. The two arms of lever 205 are offset, and the left hand end of lever 205 is pivotally connected by a link 206 to the upper portion of quadrant 187 (Figures 10, ll). The right hand end of lever 205 carries a roller 208 which cooperates with the rims of spool 203 (Figures 8, 9).

The arm 200 also carries a scale 210 which is the same functionally as scale 110 of machine 20. Pointer 211 is pivoted to frame member 121 so that its outer end traverses scale 210 and its inner end engages a projecting portion of quadrant 187 to be raised or lowered thereby, In Figure 8, the pointer 211 is shown in the zero position that it occupies when the axis of tool base pivot 190 is aligned with the center of drive pin 144 (see Figure 10). The center of drive pin 144 thus affords a common starting point for the measurements made with both scales 175 and 210.

The operation of machine 120 is on all fours with that of machine 20. Indeed, by raising the reference numerals by 100, the description of the operation of machine will fit machine 120 exactly.

It has been determined experimentally that machines built in accordance with the herein disclosed machines 20 and 120 can be adjusted to operate with great accuracy and will generate commercially satisfactory concave and convex toric surfaces on ophthalmic lenses over the ranges of base and cross curves usually required. Of course, it will be understood that the generated lens surfaces must be subjected to subsequent finishing operations.

lt will be apparent that a different arrangement of parts would enable the tool to be swung past the work instead of vice versa as in machines 20 and 120. Also, by a considerable redesign, but without departing from the essentials of the herein disclosed machines, it would be possible to combine the functions of generating concave and convex toric surfaces in a single machine.

While there are herein described, and in the drawings shown, illustrative embodiments of the invention, it is to be understood that the invention is not limited thereto, but may comprehend other constructions, arrangements of parts, details and features without departing from the spirit of the invention. We desire to be limited, therefore, only by the scope of the appended claims.

We claim:

1. A machine for generating curved surfaces comprising a frame member, a swing member adapted for oscillation about a predetermined axis with respect to said frame member, a generating tool carried by one said member and a work holder carried by the other said member, slideways longitudinally disposed on said members, pivotally connected slide blocks slidably mounted in said slideways and adjustable therealong, a thin exible tension member for supporting said swing member, said tension member being suspended at its upper end from said frame member and having its lower end secured to said swing member, and fulcrum means for said tension member carried by said slide blocks and having substantially line contact with said tension member at either side thereof in substantially the same plane as the axis of said pivotal connection between the slide blocks, whereby the latter axis coincides with the axis of oscillation of said tension member and defines said predetermined axis.

2. The combination as claimed in claim l in which said fulcrum means comprises two rollers rotatably mounted on the block that slides in the frame member slideway.

3. The combination as claimed in claim l in which said tension member is suspended from said frame member at a point lying above and centrally of the frame member slideway and said tension member is secured to said swing member at a point lying below and centrally of the swing member slideway.

4. The combination as claimed in claim l in which a rack and pinion mechanism is used for slidably adjusting said slide blocks along said slideways.

5. A machine for generating toric surfaces on lenses comprising a frame member, a swing member adapted for oscillation about a predetermined axis with respect to said frame member, a grinding wheel adjustably mounted on one said member and a lens holder adjustably mounted on the other said member, slideways longitudinally disposed on said members, pivotally connected slide blocks slidably mounted in said slideways and adjustable therealong, a thin flexible tension member for supporting said swing member, said tension member being suspended at its upper end from said frame member and having its lower end secured to said swing member, and fulcrum means for said tension member mounted on the block that slides in the frame member slideway, said fulcrum means having substantially line contact with said tension member at either side thereof in substantially the same plane as the axis of said pivotal connection between the slide blocks, whereby the latter axis coincides with the axis of oscillation of the tension member and defines said predetermined axis.

6. A machine for generating toric surfaces on lenses comprising a frame member, a swing member adapted for oscillation about a predetermined axis with respect to said frame member, a grinding wheel mounted on said frame member for adjustment of the Wheel axis angularly with respect to the vertical axis of the frame member, a lens holder mounted on said swing member for adjustment longitudinally thereof, slideways longitudinally disposed on said members, pivotally connected slide blocks slidably mounted in said slideways and adjustable therealong, a thin flexible tension member for supporting said swing member, said tension member being suspended at its upper end from said frame member and having its lower end secured to said swing member, and fulcrum means for said tension member mounted on the block that slides in the frame member slideway, said fulcrum means having substantially line Contact with said tension member at either side thereof in substantially the same plane as the axis of said pivotal connection between thc slide blocks, whereby the latter axis coincides with the axis of oscillation of the tension member and defines said predetermined axis.

7. A machine for generating toric surfaces on lenses comprising a frame member, a swing member adapted for oscillation about a predetermined axis with respect to said frame member, a grinding wheel mounted on said frame member for adjustment of the wheel axis angularly with respect to the vertical axis of the frame member, a lens holder mounted on said swing member for adjustment longitudinally thereof, slideways longitudinally disposed on said members, pivotally connected slide blocks slidably mounted in said slideways and adjustable therealong, a thin flexible tension member for supporting said swing member, said tension member being suspended at its upper end from said frame member above and centrally of its slideway and having its lower end secured to said swing member below and centrally of its slideway, and fulcrum rollers for said tension member rotatably mounted on the block that slides in the frame member slideway, said fulcrum rollers having substantially line contact with said tension member at either side thereof in substantially the same plane as the axis of said pivotal connection between the slide blocks, whereby the latter axis coincides with the axis of oscillation of the tension member and defines said predetermined axis.

8. A machine for generating toric surfaces on lenses comprising a frame member, a swing member oscillatable with respect to said frame member, a thin flexible tension member for supporting said swing member l5 from said frame member, means for adjusting the position of the axis of said swing member rectilinearly, a slide adjustable rectilinearly on said frame member, a tool base pivoted on said slide for angular adjustment thereon about an axis parallel to the axis of oscillation of said swing member, a lens holder mounted on said swing member, a grinding wheel rotatably mounted on said tool base, and means including a connecting rod that is pivotally connected to said swing member for oscillating said swing member, the pivot of said connecting rod and the axis about which said tool base is angularly adjustable coinciding in the zero position of the rectilinear adjustments of said swing member and of said 10 slide.

References Cited in the file of this patent UNITED STATES PATENTS 1,984,074 McCabe Dec. 1l, 1934 2,556,604 Suddarth June 12, 1951 2,620,600 Janatka Dec. 9, 1952 2,633,675 Ellis Apr. 7, 1953 2,649,667 Cooke Aug. 25, 1953

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