US3798844A

US3798844A - Lens grinding apparatus

Info

Publication number: US3798844A
Application number: US00246692A
Authority: US
Inventors: D Hannaman
Original assignee: RIGEL Mfg Inc
Current assignee: RIGEL Mfg Inc
Priority date: 1972-04-24
Filing date: 1972-04-24
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26

Abstract

An apparatus for grinding the edges of eyeglass lenses includes a base pivotally and slidably supporting a head assembly which includes rough and fine grinding wheels. The base includes a holder for selectively rotating the lens under the grinding wheels and transport means for automatically raising, shifting and lowering the head assembly from a rough grinding position to a fine grinding position after a predetermined number of revolutions of the lens under the rough grinding wheel. An edge follower assembly accurately positions the fine grinding wheel relative to the lens at a selectable position for beveling the lens in any desired manner. After a predetermined number of revolutions of the lens holder under the fine grinding wheel, the head is automatically raised and shifted to a starting position.

Description

United States Patent 1191 Hannaman Mar. 26, 1974 LENS GRINDING APPARATUS Primary Examiner-Othell M. Simpson [75] Inventor: Donald K. Hannaman, Montague Attorney, Agent, or Firm-Price, Heneveld, Huizenga Mich- & Cooper [73] Assignee: Rigel Mfg., Inc., Whitehall, Mich. [57] ABSTRACT [22] Filed: 1972 An apparatus for grinding the edges of eyeglass lenses [21 APPL 246,692 includes a base pivotally and slidably supporting a head assembly which includes rough and fine grinding wheels. The base includes a holder for selectively ro- [52] US. Cl. 51/101 LG tating the lens under thegrinding wheels d transport [51] 11.. Cl B241) 9/16, B23q 35/04 means for automatically raising, f i and l i [58] new of Search 51/101 101 the head assembly from a rough grinding position to a 51/47 284 fine grinding position after a predetermined number of revolutions of the lens under the rough grinding [56] References cued wheel. An edge follower assembly accurately positions UNITED STATES PATENTS the fine grinding wheel relative to the lens at a select- 1,14s,194 7/1915 Hansen 51/101 LG able position for beveling the lens in any desired manl,619,358 3/1927 Maynard 51/101 LG I ner. After a predetermined number of revolutions of .666, 6 4/1 Maynard 51/101 LG the lens holder under the fine grinding wheel, the head 216931053 11/1954 Hagstromm 51/101 is automatically raised and shifted to a starting posi- 3,332,l72 7/1967 Stern 5l/l0l LG tiOrL v v 3,555,739 l/l97l Novak 51/101 LG 35 Claims, 20 Drawing Figures PATENTEDMAR26 \914 sum 01 or 10 FIG.3

PATENIEDHARZS I974 3 7 9 8 44 SHEET on HF 10 PATENTEDMARZS 1914 3798344 saw '07 0F 10 mus PATENTEDMARZB m4 3798.844

' sum us HF 10 LENS GRINDING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to a lens grinding apparatus, and specifically to an eyeglass lens edging machine for shaping the boundary of eyeglass lenses in accordance with predetermined patterns.

When shaping eyeglass lens blank to fit desired frames, the lens is first rotated under a rough grinding wheel while simultaneously moved toward and away from the grinding wheel in accordance with a pattern shaped in the configuration of the desired frame. The lens is then moved under a fine grinding wheel and again rotated in a path determined by the pattern shape to finish the edging of the lens and bevel the lens as desired for fitting into'the frame. Many existing lens grinding machines must be manually operated for shifting the lens from the roughing Wheel to the fine grinding wheel. In most existing automatic machines, the lens, rather than the grinding head, is shifted to accomplish the rough grinding and fine grinding cycles of operation. Although such machines have proven relatively efficient in the number of lenses they can handle per unit time, the accuracy of positioning the bevel on the edge of the lens has been less than desired. Also, these machines frequently lack flexibility in handling'a variety of lens shapes and/or different types of bevels. Additionally, many existing machines are bulky and take up considerable space in an optical shop as well as being expensive.

One commercially available lens grinding machine manufactured by Wernicken Company or Dusseldorf, Germany, and sold under the trademark WECO, employs a head assembly which is raisable and lowerable as well as shiftable from roughing to fine grinding positions. This machine must be manually aligned for the initial roughing operation and cannot automatically shift to a variety of presettable beveling positions for fine grinding of hidden bevels. In addition, this machine is controlled by complex and costly electrical and mechanical components.

SUMMARY OF THE INVENTION The apparatus of the present invention overcomes the difficulties of existing lens grinding machines and, in addition, provides a greater'degree of automation and flexibility in operation while simultaneously being significantly less costly.

Due to the simplified construction as compared with the relatively complex existing machines, the apparatus of the present invention is easier to operate and has fewer maintenance problems.

It is an object, therefore, of the present invention to provide an improved lens grinding apparatus.

It is an additional object of the present invention to provide a lens grinding apparatus which automatically cycles through rough and fine grinding operations by moving a grinding head assembly relative to a lens.

It is a further object of the present invention to provide a lens grinding apparatus which has presettably registered roughing and fine grinding positions for automatically grinding a variety of selected beveled lens edges.

It is still a further object of the present invention to provide a lens grinding apparatus with unique controllable mechanical components to accurately and automatically position rough and fine grinding wheels with respect to a lens. I

Apparatus embodying the present invention include a base assembly to which is slidably and rotatably mounted a grinding head assembly including rough and fine grinding wheels. The base assembly includes means for rotatably holding a lens under one of the grinding wheels. Transport means shift the head assembly from a presettable roughing position to a presettable fine grinding position after a predetermined number of lens revolutions. Means'are provided for actuating the transport means to automatically accomplish the rough and fine grinding operations.

The invention can best be understood by referring to the following drawings and accompanying description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the grinding apparatus embodying the present invention;

FIG. 2 is a side elevational view of the right side of the apparatus shown in FIG. 1;

FIG. 3 is a side elevational view of the left side of the apparatus shown in FIG. 1;

FIG. 4 is a detailed partial plan view of the grinding head assembly partially in cross section;

' FIG. 5 is a bottom view of the grinding head assembly with the guiding wheels removed;

FIG. 6 is an enlarged detailed view of one portion of the grinding head assembly;

FIG. 7 is an enlarged view of a portion of the bottom of the grinding head assembly showing the brake mechanism in detail;

FIG. 8 is an enlarged perspective view of the brake mechanism shown in FIG. 7;

FIG. 9 is a side elevational view partially in cross section of the left side of the edge follower assembly on the grinding head assembly;

FIG. 10 is a detailed rear elevational view of the edge follower assembly;

FIG. 1 l is a detailed bottom view of the edge follower assembly; I

FIG. 12 is a perspective view of an alternative embodiment of the edge follower assembly;

FIG. 13 is a detailed plan view of the base assembly;

FIG. 14 is an enlarged cross section view of a portion of the base assembly; 7

FIG. 15 is a right rear perspective view of the base assembly;

FIG. 16 is a left front perspective view of the base assembly;

FIG. 17 is an enlarged detailed plan view of a portion of the base assembly showing a portion of the transfer mechanism;

FIG. 18 is a detailed perspective view of a portion of the transfer assembly shown in FIG.- 17;

FIG. 19 is an enlarged perspective view of the timing cam mechanism positioned on the base assembly; and

FIG. 20 is an electrical and pneumatic diagram partially in schematic and block form showing the control circuits and pneumatic components for the lens grinding apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 through 3, there is shown an exterior view of an assembled lens grinding apparatus embodying the present invention which includes a cover mounted over a base assembly 10 (not shown). A grinding head assembly is pivotally, slidably, and removably mounted to the base assembly 10 by means of an axle 23 extending through the head assembly and supported at opposite ends on

seats

22 and 24 positioned on cover 20.

The head assembly 30 includes a motor 32 mounted to a frame 31 of the head assembly. Drive means such as a belt 34 couple a rotating shaft of motor 32 to the grinding wheels within a grinding wheel housing 36. A protective cover 35 is positioned over the drive belt 34. A weight post 33 mounted to frame 31 is provided for holding annular shaped weights as desired for increasing the grinding pressure of the grinding wheels against the lens. A handle 37 is attached to the grinding head frame 31 for use in raising and lowering the grinding head assembly manually if desired although the machine is completely automatic in operation. A rectangular aperture 21 in cover 20 provides access to the lens holding means in the base assembly.

A follower shoe assembly 40 includes a follower shoe 42 mounted on the end of a cylinder 43 which is movably positioned within a sleeve 44. Sleeve 44 is attached to an arm 46 which is pivotally coupled to the frame 31 of the grinding head assembly. The sleeve 44 includes an open recessed area 44' such that graduated marks on cylinder 43 are exposed. These marks can be aligned'with indexing marks 47 on sleeve 44 by rotating an adjustment knob 48 to move the cylinder 43 within sleeve 44 for setting positive and negative lens deviations when standard lens grinding patterns are employed with the device.

Pattern holding means extends from a slotted aperture 26 in the cover 20 and includes means thereon for attaching a lens pattern which is held under the follower shoe 42. The pattern holding means rotates together with lens holding means described in detail below to control the position of the grinding head assembly and therefore the grinding wheels thereon relative to the position of the lens held within the machine.

Positioned on the grinding wheel housing is a control 54 for indexing the fine grinding wheelto place a bevel on the lens in any desired position. An indicator 52 on the top of housing 36 provides a visual reference for the operator in setting the bevel position. The edge follower mechanism associates with the control and the indicator is described in detail below.

On the front surface 28 of the cover 20 there is included an on-off electrical switch 25, a lens holding pneumatic control 27, and a start switch 29 which are operated in that sequence to initiate the automatic operation of the lens grinding machine. Having briefly described the exterior portions of the apparatus and some of the major components, a detailed description of the head assembly, the base assembly and the control apparatus will be presented in that order. These descriptions will be followed by adetailed description of the operation of the machine.

Referring now to FIGS. 4 through 12 and specifically to FIGS. 4 and 5, there is shown the head assembly 30 including the follower shoe assembly 40. The entire grinding head assembly 30 is pivotally and slidably mounted on the axle 23, as noted above, by means of bearing assemblies (FIG. 4), one of which is fitted within each of a pair of raised shoulders 82 on either side of the rear portion of the frame 31 of the grinding head assembly. The bearing assemblies 80 each include ball bearings 84 which permit longitudinal motion of the grinding head assembly 30 indicated by the arrow A and needle bearings 86 which permit rotational motion of the grinding head assembly 30 on axle 23 as indicated by the arrow B.

Also mounted within each of the shoulders 82 of frame 31 are sleeve bushings 88 within which is slidably and rotatably mounted a cylindrical sleeve assembly 90. Sleeve assembly 90 includes a sleeve 91 concentrically positioned within the bushings 88 and having an inner diameter which permits clearance between the inner surface 93 of sleeve 91 and the outer surface 23' of the axle 23. The sleeve 91 is therefore free to slide within the bushings 88 in a longitudinal direction, also indicated by the arrow A, as well as rotate within the bushings in a direction also indicated by arrow B.

The sleeve 91 includes an annular groove 92 formed around its outer circumference. Additionally, a follower pin assembly is positioned on sleeve 91 and includes a block 102 rigidly attached to sleeve 91, and a follower pin 104 extending downwardly from the head to contact the head transfer mechanism on the base assembly as described in detail below.

A brake assembly is also positioned on the underside of the head assembly 30 and includes a U- shaped brake shoe frame 112 (FIGS. 7 and 8) having downwardly depending legs 113 and a cross member 1 14. The end of the downwardly depending legs remote from the cross member 114 are rigidly attached to the frame 31 of the grinding head assembly. A brake shoe 116 is held within the frame 112 by means of suitable holding pins and 122 which extend into slots in the edges of the shoe (not shown). Shoe 116 is formed of a rectangular member having an aperture 117 which receivesthe sleeve 91 such that when the braking means 110 is in the unlocked position, the outer surface 95 of sleeve 91 is free to move within aperture 117. The shoe 116 includes a slot 118 such that the ends 119 of shoe 116 can be compressed inwardly closing the slot 118 and causing the brake shoe to bind against the outer diameter of sleeve 91. Pin 122 is adjustable to vary the gap of slot 118 to provide a brake adjustment. The actuating means for the brake shoe will now be discussed. I

A pin 124 (FIG. 7) is slidably mounted within an aperture 125 in the rear leg 113 of the brake frame 112 and has an end which contacts one side of the brake shoe near the end of slot 118 adjacent cross member 114 of the frame. Movement of the pin 124 inwardly toward the brake shoe causes the shoe to clamp the sleeve 91 (and the follower pin 104) with respect to the head assembly. This feature is employed for raising the head after the rough grinding cycle, transferring the head to the fine grinding position and lowering the head as explained in detail below.

Means for actuating the braking means by moving the pin 124 includes a solenoid 126 having a movable plunger 126 which is attached to a first pivot arm 128 by means of a pivotable coupling 127. Arm 128 is coupled to a second pivot arm 130 by means of a pivotable connection 129. Member is pivotally attached to shoulder 82 of the frame 31 by means of a pivot pin 132. A tapered recess 134 is formed in'one corner of member 130 as shown in FIG. 7 and receives a tapered end of third arm 136. Arm 136 is pivotally coupled to the frame 112 of the braking means by means of a pivot pin 138. The end 139 of arm 136 includes a protruding ear which is adapted to contact the end of pin 124. Pin 124 can be spring-loaded to hold the arm 136 against an arm stop 142 on shoulder 82. The braking mechanism is shown in FIG. 7 in its unlocked position. When the solenoid 126 is actuated, the plunger 126 of the solenoid moves in a direction indicated by arrow C to cause the arm 130 to pivot about pin 132 in a counterclockwise direction thereby forcing the arm 136 away from a stop pin 42 by means of the recessed slot 134 in arm 130. Arm 130, which rotates in a clockwise direction about pin 138, forces the pin 124 against the brake shoe 116. In this manner, the actuation of the solenoid 126 causes the brake means to lock the sleeve 91 relative to the housing 31. When the solenoid 126 is not actuated (during the rough grinding), the follower assembly 100 is free to rotate together with the sleeve 90. The follower pin 104 is biased in a rearward position by means of a bias spring 106 which extends between the block 102 and a follower arm pivot pin 108 as seen in FIGS. 4 and 5. A recess 107 on pin 108 accommodates the end of spring 106 to hold it in a fixed position.

An adjustment means (FIGS. 7 and 8) is provided for sliding sleeve 91 with respect to the housing 31 in a manner which, as explained below, indexes the rough grinding wheel to the lens. The adjustment means 150 includes a pivot arm 152 which is pivotally mounted to the head assembly frame 31 by means of a pin 153. A pin 154 extending from end 151 of arm 152 fits within the annular groove 92 in sleeve 91 to cause the sleeve 91 to shift laterally (arrow A in FIG. 4) as arm 152 is pivoted about point 153. An adjustment screw 155 is threadably mounted through the edge 38 of frame 31 and has an end pivotally mounted to an end 157 of arm 152 by means of a pivot pin 158 and screw receiving slot 159. An adjustmentknob 156 is provided on the opposite end of the screw 155.

The head assembly 30 further includes a head raising and lowering cam follower plate 160 (FIGS. 5 and 7) which extends outwardly from one side of the head assembly. When the head assembly is mounted to the base assembly as described below, this plate will contact a roller cam follower coupled to a movable member on the base for raising and lowering the grinding head assembly. Plate 160 is mounted to the shoulder 82 on the frame 31 by means of suitable mounting bolts (not shown).

A grinding wheel shaft is rotatably mounted in the forward end of frame 31 of the grinding head assembly by means of a pair of spaced bearings 166 fitted in the frame 31. A pulley 167 at end 164 of the shaft is adapted to receive the drive belt 34 (FIG. 2) which is coupled to the grinding wheel drive motor 32.

A fine grinding wheel is mounted on the opposite end of shaft 165 and a rough grinding wheel is positioned outwardly from wheel 170. Both of these wheels are rigidly attached to shaft 165 by means of a suitable mounting bolt 172 secured to a threaded aperture 168 in the end of shaft 165. It is noted that the fine grinding wheel 170 includes an annular V-shaped notch 172 therearound for beveling edges of the lenses as described below.

The follower shoe assembly 40 is pivotally coupled to the grinding head assembly 30 by means of an aperture 49 in the arm 46 and bushings 49 within aperture 49 that are adapted to' receive in pivotal engagement therewith, the end 109 of pivot pin 108. A follower pin 41 extends inwardly toward the grinding head assembly from the end of arm 46 opposite the follower shoe 42. This pin contacts sensing means (FIGS. 4 through 6) to provide means for actuating the sensing means to cause the rotatable lens holding means (described below) to stop and start rotation of the lens blank as the continuously rotating grinding wheel removes lens material from the lens.

The sensing means is best shown in FIGS. 4 and 6 and includes a slidable plate 182 coupled to the shaft 184 of a spring-loaded pneumatic cylinder 185. The shaft 184 is pivotally movable in cylinder 185 thereby allowing plate 182 to pivot about the axis of shaft 184 as well as slide in a direction indicated by arrow D when the shaft 184 moves in and out of cylinder 185. Plate 182 is shown in the forward position in FIG. 6 and moves rearwardly when the cylinder is actuated. The air cylinder 185 is attached to a mounting bracket 186 which in turn is attached to frame 31 by suitable bolts 187.

Adjustable camming means 190 comprise a threaded member 191 fitted through the end 183 of plate 182. Member 191 has a flat head or cam surface 192 which is positioned to contact the pin 41 of the follower shoe assembly as shown in FIG. 6 during the roughing cycle of operation when the air cylinder 185 is not actuated and the plate 182 is in its forward position. During the fine grinding operation, cylinder 185 is actuated to slide the plate 182 rearwardly such that pin 41 will contact the upper surface 181 of plate 182 forward of -member 190. As explained in detail, the differential distance between the cam surfaces 192 and plate surface 181 allows the fine grinding wheel to remove approximately 2 mm of additional lens material during the fine grinding cycle of operation.

The end of plate 182 opposite end 183 includes an adjustable follower 194 (FIG. 8). Member 194 has a surface or head- 195 which extends through an aperture 196 in the frame 31 of the grinding head assembly to contact a follower arm (not shown) of electrical switch 197 (FIG. 2) mounted on the top of frame 31. The actuation of this switch as the follower arm assembly pivots about pin 108 due to the'rotation of pattern 70 under follower shoe 42 causes the lens holding motor (described below) to be selectively actuated as the lens material is removed by the grinding wheel during the rough and fine grinding cycles. The operation of this control is explained in greater detail below. In addition to the follower shoe assembly, the sensing means, the transport engaging means, the braking means, and the grinding wheels; the grinding head assembly 30 further includes edge following means 200 which is attached to the grinding wheel housing 36 and is shown in detail in FIGS. 9 through 12.

In the embodiment shown in FIGS. 9 through 11, the edge following means includes a follower shoe in the form of an arm 202 having a rounded end 204 adapted to contact the edge of a lens held by the lens holding means under the grinding wheel. The arm 202 is supported under and movably adjacent the fine grinding wheel 170 by means of a shaft 206 which extends upwardly through the housing 36 and is rotatable therein to adjust the position of end 204 with respect to the notch 172 in wheel 170.

At the top of the housing 36, there is provided an indicator 210 including an indicator arm 208 also coupled to the shaft 206 and movable therewith. A guide 212 is rigidly attached to the top of the housing 36 and has a notch 213 therein which corresponds in vertical alignment to the notch 172 in wheel 170. The indicator arm 208 has a pointer end 209 which corresponds to and tracks the position of the end 204 of arm 202. An adjustment screw 215 is coupled to a pivot coupling 205 movably positioned in a recess 207 in housing 36 to rotate the shaft 206 for providing an adjustment for positioning the bevel with respect to the lens in a manner described in detail below. An adjustment knob 54 is positioned on the end of screw 215.

In the FIG. 12 embodiment, the arm 202 is replaced by an arcuate-shaped follower shoe 220 which is adapted to contact the edge of a lens and is attached to a block 224 having a dovetailed tongue 221 coupling block 224 to a correspondingly shaped notch 223 in an end block 225 of a mounting bracket 222. Bracket 222 is rigidly attached to the inner wall of the housing 36 by means of a bolt 226. The shaft 206 which extends upwardly through the housing 36 is identical to the shaft described in conjunction with the embodiment shown in FIGS. 9 through 11 as are the indicator and adjustment means. Shaft 206, however, is coupled to block 224 by means of a pivot arm 228 and a springable connection 230 which couples the end of the shaft 228 remote from its junction with shaft 206 to the sliding block 224. In one embodiment, the block 224 had a rectangular aperture formed therein and'the end of member 230 was tapered to fit within the aperture such that, as shaft 206 is rotated during adjustment, the rotational motion is converted into a linear motion which causes the follower shoes 220 to move inwardly in a direction vertical to the plane of grinding wheel 170. The FIG. 12 embodiment provides linear motion of the follower shoe as compared to the rotational counterpart shown in FIGS. 9 through 11.

Having described in detail the construction of the grinding head assembly and its subassemblies, a description of the base assembly to which the grinding head assembly is slidably and pivotably coupled is now presented.

The base assembly shown in FIGS. 13 through 19 includes a frame 250 having front corner posts 252 and 254 and an L-shaped upstanding rear corner member 256. Centrally located toward the front edge of the frame 250 is an open rectangular housing 258 having a rear wall 259, a left side wall 260, a front wall 261, a right side wall 262, and a floor 263. An aperture 264 in the floor 263 provides a drain for liquid coolants and lubricants employed with the lens grinding apparatus. Extending in the housing 258 is the lens holding means 270 which includes a left lens mounting bracket 272 mounted on a shaft 274 which extends through the left side wall 260 of housing 258 by means of a suitable bearing or bushing 275. The lens holding means 270 further includes a right lens mounting bracket 282 attached to a shaft 284 extending through the right side wall 262 of container 258 by means of a suitable bushing or bearing 285 (FIG. which permits shaft 284 to rotate as well as move laterally through wall 262 as indicated by arrow D. The specific details of the shaft arrangement are described below..

Shaft 274 has a cog belt pulley 276 attached thereto to be rotatably driven by means of alens holder drive motor 290 which includes a gear reduction box 292 attached thereto with an output cog pulley 294. A first cog belt 295 couples pulley 294 to one of a pair of cog pulleys 296 mounted on a shaft 297 which extends through the rear wall 259 of container 258 and is rotatably mounted thereto by means of suitable bearings (not shown). A second drive belt 298 couples the inner pulley 296 to the pulley 276 mounted on the shaft 274 adjacent the left wall 260 of container 258. In the embodiment shown, the

shafts

297 and 274 driven by motor 290 are rotated at a speed of 10 rpm when the motor 290 is actuated.

Shaft 284 is a solid shaft which extends through a hollow shaft 280 which is supported at one end by the bearing 285 in wall 262 and at the other end by a bearing 309 in a vertical support bracket. Shaft 280 includes a bushing 282 therein (FIG. 14) which is keyed to shaft 284 by means of key 283 such that shaft 284 can slide within shaft 280 and will be rotatably driven thereby. Shaft 280 is rotatably driven by a third cog belt 286 coupling a cog pulley 287 attached to the shaft 280 adjacent side wall 262 of housing 258 and a cog pulley 288 on shaft 297. A fourthcogbelt 298 is positioned'over a cog pulley 299 at the right end of shaft 297 for driving a cam timing means 400 at a one-to-six reduced speed ratio in the preferred embodiment. The timing cams will be described in greater detail below.

It is seen with the structure shown, the lens clamping means 272 and 282 are coupled to

shafts

274 and 284 which are rotatably driven at approximately 10 rpm when motor 290 is actuated. The left end of shaft 274 extends through a shoulder 277 by means of a bearing 278 therein and includes the pattern holding means such as a spring ball mounting bracket 279 on which a standard lens grinding pattern can be detachably coupled. The pattern, therefore, will be rotated at the same speed as the lens since they are mounted on a common shaft.

A coolant nozzle 288 is mounted in the housing 258 through the left side wall 260 and is coupled to a suitable source of coolant and lubricating fluid by means of a hose 289. The nozzle 288 is positioned to direct coolant under-pressure over the lens held between the

jaws

272 and 282 during the lens grinding operation. The coolant is then drained by means of the aperture 274 in the floor of the housing.

Clamping means 300 is provided for securely clamping a lens blank between

jaws

272 and 282. Means 300 includes a pivotable arm assembly which comprises a lever arm 302 pivotally mounted to the frame 250 by means of a bolt 304. The forward end 306 of arm 302 is pivotally coupled to the right end 284 of shaft 284 (FIG. 15 A pneumatic cylinder 310 has a shaft 312 pivotally coupled to the opposite end 314 of arm 302. As cylinder 310 is actuated, shaft 284 is moved inwardly or outwardly in the direction indicated by arrow D to clamp the

jaws

282 and 272 together in a lens holding position or a lens releasing position respectively. In addition to the rotatable lens holding means and the lens clamping means including associated actuating means, the base assembly '10 further includes head raising and lowering means 320.

The head raising and lowering means is best shown in FIG. 16 and comprises a pneumatic cylinder 322 having a shaft 324 adjustably but fixedly clamped to an end slot of an L-shaped slide 326 formed from-flat stock. The slide 326 is positioned above the cylinder 322 by means of a pair of spaced brackets 328. Each of the brackets 328 includes a rectangular slot 329 for slidably and guidably holding the slide 326 and a cover plate 330 which extends over the slide 326. Suitable lubrication can be provided on the plate 326 and around the apertures 329 of brackets 328 to facilitate the movement of the slide plate 326 as the cylinder is actuated. A roller cam 332 shown in FIGS. 15 and 16 comprises a post 334 to which is attached a roller bearing 336 by means of a suitable bolt 338.

The head raising and lowering means 320 is shown with the slide 326 in its rearward position which corresponds to the head lowered position. The cam follower plate 160 shown in FIGS. and 7 and shown in phantom form in FIG. 17 is adapted to be contacted by the roller cam 332 when the cylinder 322 is actuated. Thus, when the head is to be raised to a starting position prior to the grinding operation, the slide plate 326 will be moved in a direction indicated by arrow E in FIG. 17 such that the roller cam 322 contacts plate 160 and moves the plate forward thereby raising the grinding head assembly which pivots about the axle 23 seated in the cover seating brackets 22 and 24 (FIGS. 1 through 3). As the grinding apparatus is operated, the cylinder 322 is actuated by a two-way valve 460(FIG. 20) to cause the shaft 324 to move in a direction opposite arrow E thereby lowering the head until the cam following plate 160 no longer contacts the roller cam 332 thereby providing free floating of the head assembly without interference from the head raising and lowering mechanism 320. The head raising and lowering mechanism 320 is actuated therefore only at the beginning of the grinding operation and at the end of the fine grinding cycle of operation.

The base assembly 10 further includes head transport means 350 (FIGS. 13, through 18) which are utilized to shift the head from a rough grinding position to the fine grinding position. This involves a laterally shifting motion of the grinding head assembly 30 as well as the raising and lowering of the assembly. The head transport means 350 includes a housing 360 having a forwardly protruding L-shaped member 362 that extends between two parallel guide tracks 364 and 366 (FIG. 16). The follower pin 104 of the head assembly 30 is adapted to rest within a notch portion 363 of the L-shaped member 362 as shown in FIG. 17 (during the roughing cycle of operation). The open edge 365 of notch 363 is tapered as shown in FIGS. 13 and 17 for the purpose described below.

Plates

364 and 366 are supported on the base 250 of the base member 10 by means of suitable support brackets 367. The rear edge 361 of housing 360 has a lip portion 371 (FIG. 17) which extends over a guide and camming plate 372 mounted on the rear shoulder 356 of the base 250 such that the housing 360 is supported between the

parallel guide rails

364 and 366 and the rear plate 372. Under the lip 371 is positioned a roller cam follower 375 (FIG. 18) which is adapted to contact the leading edge 373 of plate 372. The right end 374 of edge 373 is tapered somewhat as shown in FIG. 18 for the purpose described below. Housing 360 has a central recessed or open area 368 (FIG. 15) to permit the housing to clear the actuation cylinder 382 forming a part of the actuating means 380 for the transfer means 350.

In the mounting arrangement for the housing.360, it is seen that it is slidably positioned such that it can move transversely, as indicated by the arrow F in FIG. 18. The shaft 384 of cylinder 380 is attached to the end of the housing 360 by means of a nut bolt 385 (FIG. 18). The opposite end 386 of cylinder 382 is pivotally mounted to the shoulder 256 on base 250 by means of a pivot pin 387. Thus, cylinder 382 is permitted to pivot about point 387 The spacing between the front surface '376 (FIG. 16) of housing 360 which abuts the rear sides of the

guide rails

364 and 366 and the roller cam 375 which abuts the leading edge 373 of plate 372 permits the housing 360 to move fore and aft slightly as indicated by the arrow G in FIG. 18. The pivotal mounting of the end 386 of cylinder 380 permits such motion of the housing 360 which is rigidly attached to the shaft 384 of cylinder 382. As seen in FIG. 17, the follower pin 104 which is spring-biased in a rearward position by means of the spring 106, will normally hold a housing 360 in its rearward position against the plate 272.

In the roughing position, the housing 360 will be in the extreme left position as shown in FIG. 17 and pin 104 will be seated firmly in the corner of notch 363 of I the L-shaped bracket 362 extending from housing 360. When transferring the head from the roughing position to the fine grinding position, cylinder 382 is actuated to draw the housing 362 toward the cylinder which in turn causes the roller cam 375 to travel along the tapered end 374 of plate 372 thereby forcing the housing 360 toward the frontof the lens grinding apparatus. This pushes pin 104 forwardly in a manner to raise the grinding wheel approximately 1 mm. This results since the brake means is in a locked position during the transfer and movement of pin 104 rotates the grinding head assembly to raise the grinding wheel. Cylinder 382 includes speed regulating means such that when actuated, it will move slowly. As the housing 360 continues its motion to the right, the edge follower shoe 220 (FIG. 12) which is coupled to the grinding wheel housing, contacts the edge of the lens thereby preventing additional motion of the grinding head assembly on axle 23. This causes pin 104 to slide out of the notch 363 in member 362 and drop off the tapered end 365 thereof 'to lower the grinding head assembly which is now indexed in a preset position such that the fine grinding wheel is positioned over the lens in accordance with the setting of the edge following indicator. Since the grinding head assembly slides very freely on axle 23, pin 104 will follow member 362 until the edge follower contacts the lens.

Thus, it is seen that the transport mechanism 350 initially raises the head at the end of the rough grinding, shifts the head laterally into alignment for fine grinding, and finally, lowers the head into the fine grinding position. The novel construction of the head transport apparatus provides these functions at a minimal expense and complexity of the mechanism. An electrical switch 390 (FIG. 18) is positioned on the end of the plate 372 such that the right surface 378 of the housing 360 will actuate the switch when the housing has moved to its right position corresponding to the fine grinding position of the head. The actuation of this switch will condition the lens grinding motor 290 to be actuated on demand for rotating the lens during the fine grinding cycle of operation.

The base assembly of the lens grinding apparatus additionally includes a timing cam means 400 (FIGS. l3, l5, 19) which is mounted behind the lens housing 258. The timing cam means 400 includes a cog pulley 402 which is driven by the motor 290 via belt 298 which extends between the pulley 402 and pulley 299 on shaft 297. The pulley 402 is six times greater in diameter than pulley 299 thereby providing a one-to-six reduction in speed therebetween. Thus, for each complete revolution of the pulley 402, the lens blank 410 (shown in FIG. 13 attached to jaw 272 for illustrative purposes) has rotated six times. Pulley 402 is mounted on a shaft 404 and supported in rotatable engagement to the base 250 by means of a suitable mounting bracket 408 with bearings (not shown) therein. Also mounted to shaft 404 are three

cams

412, 414, and 416. As seen in FIGS. 13 and 19,

cams

412 and 414 are identical and have raised and lowered surfaces which each span approximately 130 of the cam surface. Cam 416 on the other hand, has a single depressed region 417 for only approximately 15 of the cam surface. Mounted in proximity to the

cams

412, 414, and 416 are three cam operated controls comprising a pneumatic switch 422 having a roller follower 423 which contacts the surface of cam 412, an electrical switch 424 having a roller cam follower 425 which contacts the surface of cam 414, and an electrical switch 426 having a roller follower 427 which contacts the surface of cam 416. With the gear reduction ratio selected as described in the preferred embodiment, after approximately two and one-half revolutions of the lens under the lens grinding wheel, the

cams

412 and 414 will actuate the valve 422 and switch 424 respectively to cause the head transferring mechanism 350 to be actuated as well as the braking mechanism in the head assembly and the sliding cam plate 182 in the sensing mechanism 180 (in the head assembly). The lens driving mechanism is also deactivated during the period of time when the grinding head assembly is shifting from the rough to fine grinding position.

Once the transfer switch 390 (FIG. 18) is actuated, motor 290 is restarted and the cam shaft 406 is restarted to selectively continue its rotation on demand until the sixth rotation of the lens has been completed thereby causing cam 416 to actuate switch 426. As this occurs, the head is raised by the actuation of raising member 320, the motor 290 is shut off as is the cooling motor; and the grinding head assembly is returned to its start position by the actuation of cylinder 382. This operational sequence is discussed in greater detail below. Thus, it is seen that the timing cam mechanism 400 together with the switches coupled thereto provide complete and automatic control of the various components shown and described which are mounted in the grinding head assembly 30 and the base member 10.

In addition to the mechanism previously described, control relays 430 and 440 are mounted on the base 250 as shown in FIG. 13. The rear shoulder 256 includes a pair of power outlet jacks 445 and 450 which are employed to provide switched power outlets to control an air compressor 465 (FIG. 20) for the lens grinding apparatus and a coolant pump 470 (FIG. 20) for the apparatus as described below. A 115 volt AC input power to the control apparatus is provided by means of the power cord 460 shown in FIG. 15. Suitable electrical and'pneumatic connections between the base member 10 and the grinding head assembly is provided by means of a bracket 472 (FIGS. 15 and 16) having a plurality of pneumatic couplings 475 together with their associated hoses 476 and an electrical terminal board 480 together with various electrical terminals 485 thereon. Mating plugs and jacks 490 and 495 respectively (FIG. 20) are provided to allow the quick disconnection of the head from the base.

The bracket 472 and terminal board 480 can be positioned as shown in the figure on the top surface of the guide plate 364 at the right end where it does not interfere with the movement of the grinding head assembly. It is noted here that the base platform or frame 250 can be cast to form the various support shoulders or brackets as well as the lens housing and other mounting structure for remaining components. Likewise, the housing 360 can be cast from suitable material such as steel. The frame 250 includes adjustable legs, 255 positioned on the four corners to provide leveling of the apparatus on a work table or the like.

Having described the mechanical construction of the lens grinding apparatus embodying the present invention, a description of the operation of the device together with the electrical and pneumatic controls is presented in conjunction with FIG. 20. It is noted here that the reference numerals assigned the various switches, valves, relays, and other components are identical in FIG. 20 to those assigned in the previous figures.

OPERATION First, a pattern 70 is selected for a desired eyeglass means 60. The pattern will indicate thepositive or negative correction factor which must be entered into the machine by means of the adjustment 48 (FIG. 1) to the pattern follower assembly 40. The graduated scale 45 is aligned with the indicator marks 47 for the desired correction factor.

The position of the roughing wheel which is shown in phantom form in FIG. 13 is next adjusted in relation to the position of the lens blank held by the

jaws

272, 282. Knob 156 shown in FIGS. 7 and 8 and which is on the right underside of the lens grinding head is used for this adjustment and indexes the position of the rough grinding wheel relative to the lens blank. Normally, this adjustment need only be made after the roughing wheel has become worn and it is desired to move the head assembly over slightly to compensate for this wear. The lens bevel indexing is then programmed into the machine by the adjustment screw 54 on the right side of the housing 36 over the grinding wheels. The indicator arm 208 on the top of the housing 36 will indicate the indexed position of the edge of the lens blank with respect to the notch bevel in the guide 212 adjacent the indicator. Thus, by adjusting knob 54, any desired bevel position on the lens can be preset such that the grinding head assembly will automatically shift to the desired position after the roughing cycles of operation to fine grind the edge of the lens and simultaneously bevel the lens at the desired position.

The air compressor 465 which is shown in FIG. 20 in block diagram form, and which is used to supply pneumatic pressure for the various cylinders in the apparatus can be operated by plugging the electrical supply line for the compressor into the switched plug 445 at the rear of the lens grinding apparatus. Likewise, a coolant pump and fluid supply 470 can similarly be powered by connecting the coolant pump to the switched output jack 450 at the rear of the lens grinding apparatus.

Once the initial adjustments for the roughing position and the lens bevel position have been preset as well as the pattern correction factor, the power on-off switch 25 (FIGS. 1 and 20) is switched to the on position which actuates the continuously running grinding motor 32 as well as the air compressor. As the air pressure builds up once the air compressor is actuated, the head lift cylinder 322 will move in the direction indicated by arrow E in FIG. 17 to raise the head assembly 30.

Next, the lens blank 410 is clamped within the jaws by operating the pneumatic valve 27 on the front panel 28 of the apparatus. When this valve is actuated, the pneumatic cylinder 310 is supplied air pressure to cause the shaft 284 to clamp the lens blank into position. The cylinder 310 remains actuated until valve 27 is again switched to the open" position at the end of the lens grinding operations. With the adjustments set and the lens in place, the only remaining operator step is to momentarily depress the start switch 29. Actuating switch 29 initiates a sequence of operations which automatically effect the rough and fine grinding of the lens toshape the lens blank in conformity with the desired pattern. 1

Depressing the start button 25 actuates the relays 430' and 440 by applying power from

input terminals

482 and 484 through

coils

432 and 442 respectively. Relay 430 has a pair of contacts 434 which close to apply power to the lens motor via

switches

197, 390 and 424. Relay 440 has a pair of

contacts

444 and 446 which close to apply power to the cycle switch 426 and to a solenoid valve 460 which applies pressurized air to the head moving cylinder 322 to cause it to move rearwardly (in the opposite direction of arrow E in FIG. 16). At this occurs, the follower plate 160 mounted to the frame of the head assembly follows the roller cam 322 on the slide plate 326 such that the head is lowered gradually with the roughing wheel being positioned above the edge of the lens blank. As the slide plate 326 of the head lowering mechanism 320 moves rearwardly, the coolant microswitch 475 which is positioned on bracket 476 rearward of cylinder 322 as shown in FIG. is actuated to actuate the coolant pump 470 which supplies a lubricating coolant to the lens blank via nozzle 280.

The depth microswitch 197 which is in series with the lens motor 290 circuit is normally in an open position. Thus, as the grinding head assembly is lowered and contacts the lens blank, the blank will be stationary until the rough grinding head lowers (by grinding away lens material) until the cam pin 41 on the follower shoe assembly has contacted the camming surface 192 (FIG. 6) of the sensor such that the plate 182 will pivot to cause the microswitch 197 to close. As this occurs, the lens motor 290 is actuated and rotates the lens holding means bringing new lens material under the rough grinding wheel and lifting the head such that the microswitch 197 again opens.

It is noted here that the grinding pressure is due to the weight of the grinding head which can be adjusted by placing annular shaped weights over post '52 (FIG.

1). By use of depth switch 197, the rotation of the lens blank is controlled by demand in a pulsating manner to grind the edge of the material on the lens blank. The

follower shoe which rides on the pattern will raise and lower the entire grinding head assembly by means of its connection with shaft 108 such that the grinding head can only be lowered to a predetermined desired position relative to the center of the lens grinding shaft 274. This assures that a desired lens configuration will be obtained. Since the braking means is not actuated, the follower pin 104 is free to rotate on sleeve 92 thereby allowing the grinding head to track the pattern and lens blank during roughing.

The rotation of the lens blank within'the lens holding means also rotates the cam assembly 400 which controls the cam transfer valve 422, the roughing microswitch 424, and the cycle microswitch 426. The cams are shaped to provide approximately two and one-half revolutions of thelens blank before the

cams

412 and 414 actuate valve and

microswitch

422 and 424 respectively.

The roughing microswitch 424 closes to actuate the brake solenoid 126 which, as described above, causes the downwardly depending pin 104 to be rigidly positioned with respect to the grinding head assembly to permit the transfer and raising and lowering of the grinding head assembly during the transfer from rough to fine operation. It is recalled that during the roughing cycle of operation, the pin 104 and the sleeve to which the pin is rigidly positioned are freely rotatable within the bushings 88 (FIG. 4). Moving of the roughing switch 424 disconnects the lens drive motor 290 and, at the same time, it actuates the brake solenoid 126. Cam 412 at approximately the same time actuates the cam transfer valve 422 mounted adjacent thereto at approximately the same time to actuate the transfer cylinder 382 as well as the spring-loaded plate cylinder 185. Since these cylinders are pneumatically operated, and the brake is electrically actuated; the brake will be fixed to lock the following pin 104 with respect to the head assembly before the transfer valvev 382 begins moving the housing 360 and the head assembly therewith transversely from the rough to the time grinding position. The plate cylinder causes the plate 182 of the sensing means 180 to move such that the cam pin 41 will no longer contact the raised camming surface 192 but rather will contact the top surface 181 of the plate 182. This allows the fine grinding wheel to penetrate a slightly greater depth (approximately 2 mm) into the lens shape for the fine grinding operation. Cam surface can be adjusted by means of the screw 191 as well as the cam 194 which contacts the follower on the depth microswitch 197 to assure that the finding grinding wheel removes the desired amount of lens material from the edge of the lens after the rough grinding to accomplish the desired bevel and finishing surface.

As the transfer cylinder 382 is actuated, it slowly begins moving from left to right to shift the fine grinding wheel 170 into position over the lens. As this occurs, it is recalled that cam follower 375 on the housing 360 causes the housing 360 and therefore the head assembly via its connection with follower pin 104, to move slightly thereby raising the head sufficiently to insure that the fine grinding wheel will clear the lens as the transfer takes place. As the housing 360 moves toward the cylinder, the pin 104 which rides in the notch 363 of the housing 360 (FIG. 17) has sufficient weight against the edge of the notch to allow the head to freely slide over the axle 23 by means of the bearings 84 until the shoe 220 of the edge follower assembly contacts the edge of the lens blank. This prevents further motion of the head assembly which then causes the pin 104 to slide away from the notch 363 as cylinder 382 continues moving the housing 360 toward the right.

Since the end 365 of the L-shaped bracket 362 is tapered, the continuously rotating grinding head is gradually lowered onto the lens. At approximately the same time, the surface 378 of housing 360 contacts the transfer microswitch 390 which changes its position to provide a current path which actuates the lens motor 290 which then allows the rotation of the lens blank when the depth microswitch 197 is closed thereby providing the same pulsating grinding of the lens during the fine grinding cycle of operation as was provided in the rough grinding operation with the exception of the additional 2 mm guiding depth provided by the shifting plate 182.

The fine grinding cycle provides approximately three and one-half revolutions of the lens under the fine,

' grinding wheel indexed with respect to the notch 172 in the fine grinding wheel in accordance with the preset and indexed position of the lens edge following apparatus. After the sixth complete revolution of the lens, cam 416 actuates the cycle switch 426 and .

cams

414 and 412 return the rough switch 424 and cam transfer valve 422 to their original position. Relay 400 is deactivated thereby removing power from the head lifting solenoid valve 460 to move plate 326 forwardly thereby raising the grinding head assembly. As plate 326 clears the switch 475, the coolant supply cuts off. The actuation of cam transfer valve 422 moves the L-shaped bracket 362 to the left or roughing position such that it once again engages the follower pin 104. Likewise, the slide 182 of the depth sensing and control means 180 returns to the roughing position by means of its spring return cylinder 185. As the rough switch 424 is actuated, the brake mechanism also releases the pin 104 from its previously locked position in relation to the head grinding assembly. Thus, after the fine grinding cycle has been completed, the head raises and moves to its roughing position and the controls are reset to initiate a new cycle. The completed lens is then removed from the apparatus by switching valve 27 to its open position to cause the clamp cylinder 310 to move shaft 284 outwardly thereby releasing the lens.

It is seen therefore, that by incorporating the apparatus of the present invention, a completely automatic lens grinding machine is provided which indexes the rough grinding wheel for the roughing operation and automatically transfers the grinding head assembly to position the fine grinding wheel in an indexed position for providing a variety of presettable bevels for the lens being ground. Once the roughing and fine grinding cycles have been completed, the lens grinding apparatus returns to a starting position such that a new cycle of operation can be initiated on a different lens blank. It is apparent that various modifications to the present invention can be made by those skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

6 l. A lens grinding apparatus for holding a lens and performing rough and fine grinding operations thereto comprising:

a base assembly including rotatable lens holding means;

a grinding head assembly including rough and fine grinding wheels thereon, said grinding head assembly movably mounted to said base assembly for alternately positioning one of said grinding wheels in contact with a lens positioned in said holding means; and

means for moving said head assembly relative to said base to position one or the other of said grinding wheels into contact with a lens by sequentially raising, shifting, and lowering said grinding wheels relative to said lens holding means and in presettable registration therewith.

2. The apparatus as defined in claim 1 and further including means for controlling the grinding depth of said grinding wheels in accordance with a preselected pattern comprising:

means for rotating a pattern in predetermined relationship with the rotation of said lens;

sensing means coupled to said pattern and to said grinding head assembly for detecting the relative position of said grinding head assembly with respect to said lens for a given rotational position of said lens and said pattern; and

control means for rotating said lens and said pattern when said sensing means detects that said grinding wheel has removed material from said lens to a depth corresponding to said pattern.

3. The apparatus as defined in claim 2 wherein said moving means includes a follower member pivotally mounted to said grinding head assembly and releasably clamped thereto and extending toward said base assembly; and transport means movably positioned on said base assembly and including receiving means for releasably holding said follower member such that when said follower is clamped to said grinding head assembly and said transport means is actuated, said transport means moves to carry said follower and said grinding head assembly from a rough grinding to a fine grinding position whereupon said follower is released from said receiving means to lower said grinding head assembly for fine grinding.

4. The apparatus as defined in claim 3 wherein said transport means includes camming means for moving said follower in a direction to raise said grinding head assembly as said transport means begins to move and wherein said receiving means comprises a member having a tapered open-ended notch to allow said grinding head assembly to gradually lower when said transport means approaches a fine grinding position.

5. The apparatus as defined in claim 4 and further including an edge follower adjustably positioned on said grinding head assembly for contacting an edge of a lens as said grinding head assembly is transferred to the fine grinding position to prevent further transfer of said grinding head assembly thereby indexing the position of said fine grinding wheel relative to said lens.

6. A method of shaping lenses rotatably held in position by grinding the lens edge with a shiftable grinding head assembly having rough and fine grinding wheels, comprising the steps of:

indexing a rotating rough grinding wheel relative to a lens; 1

rotating the lens while controllably positioning the grinding wheel to contact an edge of the lens to follow a desired pattern;

moving the rough grinding wheel away from the lens after a predetermined rotation of the lens;

shifting the grinding head assembly to index a fine grinding wheel relative to the lens;

rotating the lens while controllably positioning the fine grinding wheel to contact an edge of the lens according to the desired pattern to remove an additional differential amount of lens material from the periphery of the lens; and

moving the grinding head assembly away from the lens after a predetermined rotation of the lens and shifting the grinding head assembly to the rough grinding position.

7. The method as defined in claim 6 and including the steps of:

sensing the position of the rough grinding wheel in contact with the lens;

comparing the position of the rough grinding wheel with the pattern; and

rotating the lens pattern when the relative positions reach a first predetermined relationship.

8. The method as defined in claim 7 including the steps of: sensing the position of the fine grinding wheel in contact with the lens;

comparing the position of the fine grinding wheel with the pattern; and I rotating the lens and pattern-when the relative positions reach a second predetermined relationship. 9. A lens grinding apparatus comprising: a base assembly including lens holding means for rotatably holding a lens; a grinding head assembly including rough and fine grinding wheels rotatably mounted thereto; means for mounting said head assembly to said base assembly in transversely movable and pivotable relation to said base; means for adjustably positioning said head assembly relative to a lens in said lens holding means for indexing each of said rough and said fine grinding wheels to a lens; transport means coupled betweensaid base assembly and said head assembly for moving said head assembly between a predetermined rough grinding position and a pre-determined fine grinding posi tion; and control means for actuating said transport means. 10. The apparatus asdefined in claim 9 wherein said grinding head assembly includes a follower member extending toward said base assembly and slidably and pivotally positioned on said grinding-head assembly and wherein said transport means includes a member slidably positioned on said base assembly and including means for receiving said follower member in releasable engagement therewith. I

11. The apparatus as defined in claim 10 and including means for moving said receiving means in a direction to push against said follower member of said grinding head assembly to tend to pivot said follower member in relation to said grinding head assembly.

12. The apparatus as defined in claim 1 1 wherein said grinding head assembly includes braking means for selectively fixing the pivotal position of said following member with respect to said grinding head assembly such that when said receiving means pushes against said follower member, said grinding head assembly pivots with respect to said base assembly.

13. The apparatus as defined in claim 12 wherein said means for indexing said fine grinding wheel comprises an edge follower adjustably positioned on said grinding head assembly and including a follower shoeextending in spaced relationship from the fine grinding wheel to contact an edge of a lens in said lens holding means thereby limiting the transverse motion of said grinding head assembly when said grinding head assembly moves from roughing to fine grinding positions to position the fine grinding wheel in predetermined relationship to the lens.

14. The apparatus as defined in claim 13 wherein said means for indexing said rough grinding wheel includes means for adjustably fixing the slidable position of said follower member with respect to said grinding head assembly.

15. The apparatus as defined in claim 14 wherein said follower shoe is adjustable in a linearly movable path toward and away from said fine grinding wheel.

16. The apparatus as defined in claim 15 wherein said control means includes timing cam means movable with said lens rotation and having control elements actuated by camming surfaces thereon.

17. An apparatus for grinding the edge of a lens to conform to a predetermined pattern comprising:

a base assembly including means for rotatably holding a lens;

a grinding head assembly including rough and fine grinding wheels positioned on a rotatable shaft, said assembly movably positioned with respect to said base assembly;

a follower member extending from said grinding head assembly toward said base assembly and releaseably clamped to said grinding head;

transport means movably positioned on said base assembly and including means for releaseably receiving said follower member of said grinding head; and

control means for selectively rotating said lens holding means and actuating said transport means for alternately positioning the rough and fine grinding wheels over a lens to grind the lens.

18. The apparatus as defined in claim 17 wherein said grinding head apparatus is pivotally and slidably mounted to said base assembly to be movable toward and away from a lens held by said lens holding means.

19. The apparatus as defined in claim 18 wherein said follower member is pivotally mounted to said grinding head assembly and slidably adjustable therewith, and wherein said grinding head assembly includes braking means for fixing the pivotal position of said follower member with respect to said grinding head assembly.

20. The apparatus as defined in claim 19 wherein said transport means is a housing slidably positioned between guide means to move transversely between rough and fine grinding positions at opposite limits of travel, and wherein said guide means includes camming means for moving said housing in a direction generally orthogonal to its sliding movement as it travels from the rough grinding position.

21. The apparatus as defined in claim 20 wherein said receiving means comprises an open-ended notched member extending from said housing and having a surface against which said follower member is seated, said surface being tapered away from said follower at the open end of said notch.

Claims

1. A lens grinding apparatus for holding a lens and performing rough and fine grinding operations thereto comprising: a base assembly including rotatable lens holding means; a grinding head assembly including rough and fine grinding wheels thereon, said grinding head assembly movably mounted to said base assembly for alternately positioning one of said grinding wheels in contact with a lens positioned in said holding means; and means for moving said head assembly relative to said base to position one or the other of said grinding wheels into contact with a lens by sequentially raising, shifting, and lowering said grinding wheels relative to said lens holding means and in presettable registration therewith.

2. The apparatus as defined in claim 1 and further including means for controlling the grinding depth of said grinding wheels in accordance with a preselected pattern comprising: means for rotating a pattern in predetermined relationship with the rotation of said lens; sensing means coupled to said pattern and to said grinding head assembly for detecting the relative position of said grinding head assembly with respect to said lens for a given rotational position of said lens and said pattern; and control means for rotating said lens and said pattern when said sensing means detects that said grinding wheel has removed material from said lens to a depth corresponding to said pattern.

6. A method of shaping lenses rotatably held in position by grinding the lens edge with a shiftable grinding head assembly having rough and fine grinding wheels, comprising the steps of: indexing a rotating rough grinding wheel relative to a lens; rotating the lens while controllably positioning the grinding wheel to contact an edge of the lens to follow a desired pattern; moving the rough grinding wheel away from the lens after a predetermined rotation of the lens; shifting the grinding head assembly to index a fine grinding wheel relative to the lens; rotating the lenS while controllably positioning the fine grinding wheel to contact an edge of the lens according to the desired pattern to remove an additional differential amount of lens material from the periphery of the lens; and moving the grinding head assembly away from the lens after a predetermined rotation of the lens and shifting the grinding head assembly to the rough grinding position.

7. The method as defined in claim 6 and including the steps of: sensing the position of the rough grinding wheel in contact with the lens; comparing the position of the rough grinding wheel with the pattern; and rotating the lens pattern when the relative positions reach a first predetermined relationship.

8. The method as defined in claim 7 including the steps of: sensing the position of the fine grinding wheel in contact with the lens; comparing the position of the fine grinding wheel with the pattern; and rotating the lens and pattern when the relative positions reach a second predetermined relationship.

9. A lens grinding apparatus comprising: a base assembly including lens holding means for rotatably holding a lens; a grinding head assembly including rough and fine grinding wheels rotatably mounted thereto; means for mounting said head assembly to said base assembly in transversely movable and pivotable relation to said base; means for adjustably positioning said head assembly relative to a lens in said lens holding means for indexing each of said rough and said fine grinding wheels to a lens; transport means coupled between said base assembly and said head assembly for moving said head assembly between a predetermined rough grinding position and a pre-determined fine grinding position; and control means for actuating said transport means.

10. The apparatus as defined in claim 9 wherein said grinding head assembly includes a follower member extending toward said base assembly and slidably and pivotally positioned on said grinding head assembly and wherein said transport means includes a member slidably positioned on said base assembly and including means for receiving said follower member in releasable engagement therewith.

12. The apparatus as defined in claim 11 wherein said grinding head assembly includes braking means for selectively fixing the pivotal position of said following member with respect to said grinding head assembly such that when said receiving means pushes against said follower member, said grinding head assembly pivots with respect to said base assembly.

13. The apparatus as defined in claim 12 wherein said means for indexing said fine grinding wheel comprises an edge follower adjustably positioned on said grinding head assembly and including a follower shoe extending in spaced relationship from the fine grinding wheel to contact an edge of a lens in said lens holding means thereby limiting the transverse motion of said grinding head assembly when said grinding head assembly moves from roughing to fine grinding positions to position the fine grinding wheel in predetermined relationship to the lens.

17. An apparatus for grinding the edge of a lens to conform to a pRedetermined pattern comprising: a base assembly including means for rotatably holding a lens; a grinding head assembly including rough and fine grinding wheels positioned on a rotatable shaft, said assembly movably positioned with respect to said base assembly; a follower member extending from said grinding head assembly toward said base assembly and releaseably clamped to said grinding head; transport means movably positioned on said base assembly and including means for releaseably receiving said follower member of said grinding head; and control means for selectively rotating said lens holding means and actuating said transport means for alternately positioning the rough and fine grinding wheels over a lens to grind the lens.

22. The apparatus as defined in claim 21 wherein said apparatus includes stop means positioned on said grinding head assembly and adapted to contact a lens in said lens holder for limiting the transverse motion of said grinding head assembly toward said lens and said control means actuates said braking means and drive means for moving said housing to cause said grinding head assembly to raise, move transversely toward the lens, and lower as the follower slides along said seating surface of said receiving means when said stop means contacts said lens.

23. A transport assembly for use in shifting the position of a head assembly slidably and pivotally mounted to a base member between first and second predetermined positions comprising: a base member including means for holding an article; a head assembly including means for performing a machining operation on the article held by said base, said assembly transversely slidably, and pivotally mounted to said base member and including transport engaging means extending therefrom; a transport assembly positioned on said base assembly and including a housing with a receiving member adapted to releasably hold said transport engaging means of said head assembly; bias means holding said transport engaging means in contact with said receiving member when said head is in a first position; guide means for loosely supporting said housing in slidable engagement relative to said base member; means for sliding said housing along said guide means; camming means positioned on said base member for moving said housing in a direction to raise said head assembly as said housing assembly moves from an end position corresponding to said first position of said head assembly; and stop means positioned on said head assembly to limit the travel of said head assembly thereby forcing said transport engaging means from said receiving member in a manner to lower said head assembly.

24. The apparatus as defined in claim 23 wherein said receiving member is an L-shAped member having a seating surface against which said transport engaging means is positioned, said seating surface being tapered away from said transport engaging means at the open end of said member to gradually lower said head assembly as said transport engaging means slides out of said L-shaped member to said second position.

25. A lens edge grinding apparatus for shaping a lens blank in accordance with a preselected lens pattern comprising: a base member including means for holding and rotating a lens blank and a lens pattern; a grinding head assembly movably positioned with respect to said base member and including rough and fine grinding wheels rotatably mounted thereto; means for shifting the position of said grinding head assembly to alternately position said rough and fine grinding wheels over said lens blank; a movable follower assembly coupled to said grinding head assembly and having a follower shoe contacting said pattern, said follower assembly including a cam extending therefrom; sensing means positioned on said grinding head assembly and movable between first and second positions, said sensing means including first and second cam surfaces adapted to alternately contact said cam of said follower assembly when said sensing means is in said first or second positions respectively; control means coupled to said sensing means to be selectively actuated by movement of said sensing means for selectively actuating said lens rotating means when the lens blank has been ground by one of said grinding wheels to a predetermined dimension at a peripheral point on the edge of the lens; and additional control means for shifting the grinding head assembly to position the other grinding wheel over the lens blank and to shift the position of the sensing means such that the cam contacts the other of the cam surfaces to actuate said control means to actuate said lens rotating means to remove a different amount of lens material from the lens blank.

26. The apparatus as defined in claim 25 wherein said sensing means comprises a plate having an adjustable surface at one end forming said first cam surface and a fixed surface at the same end spaced from said first cam surface, said fixed surface forming said second cam surface, said plate pivotally mounted to said grinding head assembly with said one end extending into contact with said cam of said follower assembly and an opposite end contacting said sensing means.

27. The apparatus as defined in claim 26 wherein said plate is positioned on a movable shaft of an actuatable cylinder to permit said plate to pivot about the longitudinal axis of said shaft and shift to position a different one of said first or second cam surfaces in contact with said cam when said cylinder is actuated.

28. A lens grinding apparatus comprising: means for rotatably holding a lens, said holding means including a base assembly having lens holding jaws coupled to a rotatable shaft; means for slidably and pivotally supporting a pair of grinding wheels in relationship to said holding means, said supporting means including a grinding head assembly including bearing means for supporting said assembly on said base in pivotable and slidable relation therewith; transport means including means for releaseably engaging said support means for moving said support means relative to said holding means wherein said grinding head assembly of said supporting means further includes a follower member adapted to extend into releaseable contact with said transport means; and means for disengaging said support means from said transport means when a grinding wheel is positioned in a predetermined relationship to a lens in said holding means.

29. The apparatus as defined in claim 28 wherein said transport means is slidably positioned on said base, and wherein said releaseable engaging means is adapted to receive said follower means extending from said grinding head assembly.

30. The apparatus As defined in claim 29 wherein said releaseable engaging means comprises a notched member having an open end for allowing said follower to disengage from said notched member at said open end.

31. The apparatus as defined in claim 30 wherein said disengaging means comprises a stop for limiting the motion of said grinding head assembly thereby forcing said follower out of said notched member when said grinding head assembly has reached a predetermined position relative to a lens within said holding means.

32. For use in a lens grinding apparatus including a grinding head which has a follower member pivotally attached to the head and extending into releaseable contact with receiving means on a transversely movable transport means positioned on a lens holding base, a method of transferring the grinding head between two lens grinding positions comprising the steps of: locking the follower member in a fixed position relative to said grinding head; moving the transport means from a first position to transversely move the grinding head while simultaneously raising the grinding head by forcing the follower pin in a direction lateral to the transverse movement of the transport means; and limiting the motion of the grinding head to slide the follower member from the receiving means in a manner which allows the grinding head to lower.

33. The method as defined in claim 32 and including the additional steps of: returning the transport means to the first position; raising the grinding head such that the follower member seats in said receiving means; and unlocking said follower member to permit said member to rotate relative to said grinding head.

34. In a lens grinding apparatus having a grinding head assembly pivotally and slidably positioned on a lens holding base assembly, means for transferring the grinding head assembly to alternately position one of two grinding wheels thereon in alignment with a lens, said means comprising: a transport movably positioned on said base assembly and including receiving means thereon; a sleeve pivotally positioned on said grinding head assembly and including a follower pin extending into releaseable contact with said receiving means; means for actuating said transport means to transversely move said transport and simultaneously shift said grinding head assembly transversely from a first position; cam means coupled to said transport means for forcing said follower pin in a direction which tends to raise said grinding head assembly as said transport means moves from said first position; braking means for locking the pivotal position of said sleeve relative to said grinding head assembly, and control means for actuating said braking means such that said cam means raises said grinding head assembly as said transport means shifts said grinding head assembly.

35. The apparatus as defined in claim 34 wherein said braking means comprises a shoe assembly rigidly positioned on said grinding head assembly and including a brake shoe movable into contact with said sleeve to fix the relative position of said sleeve and said grinding head assembly when said control means actuates said braking means.