US1272474A - Edge-grinding machine for lenses. - Google Patents

Description

E. M. LONG.

EDGE GRFNDING MACHINE FOR LENSES.

APPLICATION FILED IUNEZ. 1916. 1 272 474. Patented July 16, 19.18. 5 SHEETS-SHEET1.

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fl'rran/vzy E. M. LONG.

EDGE GRINDING MACHINE FOR LENSES.

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APPLICATION FILED JUNE 2, I9I6.

5 SHEETSSHEET 2.

Patented July 1( .17 Tron/ a E. M. LONG.

EDGE GRINDING MACHINE FOR LENSES.

. APPLICATION FILED JUNE 2, 1916.

QAY,

E. M. LONG.

EDGE GRINDING MACHINE FOR LENSES.

APPLICATION FILED JUNE 2. I916.

' Patented July 16, 1918 5 SHEETS-SHEET 4.

. E f-Z 5 M E. M. Lowe.

EDGE GRkNDING MACHINE FOR LENSES.

APPLICATION FILED JUNEZ. i916.

Patented July 16, 1918.

5 SHEETS-SHEET 5 o'rnn s'rarns rarn'r; orrion.

ELI MAYNARD LONG, OF GENEVA, NEW YORK, ASSIGNOR TO THE STANDARD OPTICAL COMPANY, OF GENEVA, NEW YORK, A CORPORATION OF NEW YORK.

EDGE-GRINDING MACHINE FOR LENSES.

Specification of Letters Patent. "Patent ed July 16, 1918.

Application filed June 2, 1916. Serial No. 101,282.

. Machines for Lenses, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to certain improvements in edge grinding machines for lenses,

in which the rotary lens-holder is recipro-.

f cated axially across the face of a rotary grindstone for reducing the lens to the desired form according to a predetermined pattern.

The main object is to increase the general working efiiciency of machines of this character,

First, by reciprocating the lens-holder across the face of the grinder through the medium of an oil pump and adjustable means for reversing the direction of flow of the oil from the pump and varying the distance of travel of the carriage at will.

Second, by rotating the lens (elliptical) at such differential speeds that all portions in the perimeter thereof will be finished at approximately the same time, as distinguished from the usual method whereby the lens revolves at a uniform rate of speed which grinds the ends faster than the sides.

Third, by locating the axis of movement of the rocking frame for the lens-holder in approximate alinement with the meeting points of the pitch circles of the driving gears to maintain a more uniform grinding action as the rocking support for the lensll()l(l(l' oscillates.

Fourth, by providing for a quick opening and closing movement of one of the lensclamping sections through the medium of a self-locking cam action capable of holding said sectlon in anv posulon of ad ustment.

Fifth, by bringing all of the adjustable parts of the machine will be brought out in the following description.

. In the drawmgs- 1 Figures 1 and 2 are, respectively, a top.

plan and a side elevation of an edge grinding machine embodying the various features of my invention.

Figs. 3 and 4 are enlarged vertical sectional views taken, respectively, on lines 33, and 47-41, Fig. 1.

. Fig. 5 is an enlarged detail horizontal sectional View taken on line 5-5, Fig. 4.

Fig. 6 is an enlarged vertical sectional view taken-on line 6-6, Fig. 2, showing a particularly the lens-holder and the driving means therefor, together with the cam mechanism for opening and closing the lensclanaping sections and the supporting frame for the various moving parts.

-Figs."'( and 8 are enlarged transverse vertical sectional views taken in the planes of lines 77 and 8-8, Fig. 6.

Fig. 9 is an enlarged vertical sectional view through the front portion of the machine talsen on line 99, Fig. 1.

Figs. 10 "and 11 are further enlarged horizontal sectional views taken in the planes of lines 10-10 and 1111, Fig. 9.

Fig. 12 is an enlarged "detail sectional View taken on line 1212 .Fig. 2.

Figs. 13, 11, 15,- 16, 17, 18, 19 and 20 are diagrammatic views of the cooperative disks for driving the lens-holder at different speeds showing the different relative positions whlch the disks assume at starting and at the end of each successive eighth turn during onecomplete revolution.

Fig. 21 is a face view of an elliptical lens, the radial lines showing the angles of movement corresponding to the successive positions of the disks.

Main supporting frame.

As illustrated, the main supporting frame consists of a substantially semi-circular trough-like shell or casing -1- adapted to be secured in a horizontal position to any available support for receiving and inclosing the lower half of a rotary grindstone. presently described, and confining the waste mounted upon the upper front end of the,

shield 4 directly over the grindstone and is providedwith a suitable faucet -6 for supplying moisture to the periphery of the stone.

The front portion of the frame -1 is provided with an upwardly and forwardly inclined guideway 7 along and upon which is adjustable a movable section -8-.-

for receiving and supporting a sliding earriage for the lens-holding frame and truing device, hereinafter described, the movable section -8 being held in its adjusted position by one or more clamping bolts 9, Fig. 2.

Grinding device.

As illustrated, the grinding device consists of a rotary circular grindstone 10 adapted to revolve in the frame 1, and shield 4-, and for this purpose is mounted upon a rotary shaft l1- which is journaled in suitable bearings 12 on the upper edges of opposite sides of the frame 1- and is provided at one end with a. pulley 13 adapted to be connected by a belt 1 l to any available source of power, not shown, the grindstone being held against axial movement by suitable collars on the shaft at opposite sides of the grindstone.

Sliding carriage and operating means therefor.

The top of the adjusting section 8 of the main supporting frame 1 is disposed in a substantially horizontal plane and is preferably recessed to form a lengthwise guideway -15 running parallel with the axis of the grindstone. shaft 11 in proximity to the front edge of the grindstoue -'l0 for receiving and guiding a sliding carriage --1(3 which is held against upward.displacement by dove-tail connections, shown more clearly in Fig. 3.

The adjacent sides of the section S and carriage -lG- are chambered longitudinally at -17*- and --l8, respectively, for receiving a hollow cylinder -19- which is rigidly secured to the bottom of the section S- parallel with the guideway -15- as shown more for receiving a. reciprocatory piston -20-, Fig. 9, having oppositely pro ecting piston rods 21- extending through suitable glands in corresponding end heads 22 of the cylinder, said piston 22 and its rod 21 constituting a plunger which is adapted to be operated in reverse directions by a fluid under pressure, as oil, through the medium of a power-driven pumping device, hereinafter described, and also serving to transmit similar motion to the carriage -l6.

For this latter purpose, the carriage is provided with pendent abutments '23 and 24 engaging the outer ends of the piston rods 2l-, (see Fig. 9), the abutment -23 being rigid or integral with the carriage, while the other abutment 24 t is adjustable, it being ivoted at 25 to suitable lugs on the un er side of the carriage and provided with a laterally projecting shoulder -26 registering with an adjusting screw 27 in said carriage for taking up any lost motion between the *abutments and piston rods.

As shown in Fig. 9, the central portion of the section 8 of the main supporting frame is provided with an upright pendent plump case 28 suitably secured to the unor side thereof directly under the central portion of the cylinder 19 for receiving a rotary valve 29- having an eccentric bore -30, in which is mounted a rotary impeller 31 coaxial with the axis of the valve and, therefore, eccentric to the boie thereof, said impeller being provided with one ormore, in this instance four, radial blades spring-pressed outwardly against the'walls of the bore 30--by coil springs -33, Fig. 11.

The valve 29 is fitted to turn freely in the central bore, as 28, of the pump case and is provided with a pair of ports -3l at diametrically opposite sides of the impeller, but mainly to one side of the center of the bore 30- for communication with corresponding ports in diametrically opposite side of the pump case -28 These ports -3:3 communicate with upright passages -36 in the pump case 2S which ports extend through the superposed portions of the section 8- where they communicate with radial ports 37 in the adjacent side of the-cylinder -1S) at opposite ends of the piston -20 so that if the valve 29 is in the posit on shown in Fig. 11 and the impeller is rotated in the direction indicated by the arrow in the same figure, the circulating fluid, as oil. will be drawn from the right-hand end of the cylinder through the corresponding passage +3( into the impeller chamber and then forced through the left-hand passage 3G- into the cylinder 19 at the left-hand end of the piston 20-, thereby forcing said piston to the right (Fig. 9) and efi'ecting a similar movement of the carriage l6-- in the same direction, while on the other hand 'if the valve 29 is rotated a half revolution to reverse the position ofits ports 34-, the movement of the [piston 20' and carriage will be correspondingly reversed.

The pump case 28 and cylinder -19 are secured, respectively, to the lower and.

grindstone shaft --11 through the medium of suitable connections, and for this purpose is secured to an upright shaft 40 which is journaled in the pump case 28 and is provided with a worm gear 41 keyed thereto.

' Meshing with the worm gear 4=l is a worm 42 (Fig. 3) on a horizontal shaft ,43 which is journaled in suitable hearings on the pump case 28 and frame a section 8, and is provided with a grooved pulley 44- connected by a belt -45 to a pulley 46 on the grindstone shaft 11- (see Fig. 4), thus rotating the impeller continuously as long as the grindstone is in operation.

' Automatic reverse control.

A horizontal rock shaft 47 is j ournaled in the central portion of the frame section 8 between the pump case 28 and cylinder 19,'. and preferably in the same plane as and at right angles to the axis of the impeller shaft -'40', and is provided at its inner end with a double stop pawl or escapement 48- so as to rock therewith for alternately forcing the opposite ends of the pawl into'the path of a yielding abut ment -49 which, in this instance, consti tutes a part of the lever 50' eccentrically pivoted at 51- to the 'top face of the upper disk or plate 39 of the rotary valve ring 29- so as to rotate with said ring, the lever 50- being also provided with a brake-shoe 52- for frictional engagement with'the inner cylindrical walls of the pump case 28 when the abutment 49- encounters either end of the stop pawl l8-, as shown more clearly in Fig. 10.

The friction produced by the rotary impeller 31 and also that produced by the circulation of the oiltends to rotate the valve ring -29 and lever 50 thereon, but they are prevented from such rotation by the engagement of the abutment -l9 with one end or the other of the stop pawl 48 and it, therefore, follows that if the holding end of the stop pawl is rocked from its holding position, the opposite end will be forced to a similar holding position, thus permitting the rotation of the valve ring 29 and lever -50 through a substantially half revolution for reversing the position of the ports 3 l relatively to the ports 35 and thereby reversing the direction of flow of the fluid and effecting a corresponding reversal of movement of the piston 2() and carriage l6.

The free end of the lever 50' is springpressed "forwardly in the direction of rotation by means of a spring .-53-- to release the brake-shoe 52 from frictional engagement with the innerwalls of the pump case -28 as soon as either end of the pawl 48' is withdrawn from holding engagement with the abutment -49.

On the other hand, when the abutment 49- encounters either end of the pawl at the end of each half revolution of the valve ring 29, .it will automatically force the brake-shoe into frictional engagement with the inner wall of the pump case +28, thereby aiding in stopping the further rotation of the valve ring 29 until the pawl -48 is again shifted.

The rock shaft 47 extends forwardly v throughfithe front side of the frame section -8-, as shown in Figs. 3 and 12, and is provided with an upwardly projecting radial lOO arm adapted to be operated by suitable devices on the front side of the carriage As shownmore clearly in Figs. 3 and 12, these devices consist of a pair of spaced bell-crank levers -55- having their upper ends pivoted at 56 to a forwardly pro- 1 j ecting portion 57 of the carriage 16- and their lower ends provided with pins orlugs -58-- disposed at opposite sides of the upper end of the arm '-54l-, said levers being adjustable about their pivots 56 by means of' adjusting screws -59 for permitting the operation of the stop pawl -48- and consequent reversal of the valve ring -Q9 earlier or later in the movement of the carriage in either direction, as may be desired.

It is now clear that the pins 58 not only control the direction of flow of the fluid from the impeller to the cylinder 19 for operating the piston .20- and carriage 16- in' reverse directions, but also determine the amount of movement of the carriage in either direction, such movement being preferably limited to a distance slightly less than the face width of the grindstone so that the lens which is supported indirectly by the carriage will remain in contact with the grindstone in all positions of movement of the carriage.

Lens-holding means and operating means therefor.

The carriage 16 is provided at is opposite ends with upwardly and rearwardly projecting arms carrying at their upper ends pivotal screws -(31 engaging and supporting the opposite ends of a forwardly and rearwardly oscillating frame 62 for receiving and supporting a lens holder --G3 and operating means therefor, the frame 62- being hollow and fluid-tight to receive a quantity of oil or other lubricant for lubricating the various moving parts therein.

Secured to one end of the frame 62 above its axis of movement is an extension (34 in which is journaled a shaft 65 to which rotary motion is transmitted from the grinder shaft 11- through the medium of the shaft -i3 and suitable connections between the shaft 43- and 65.

As illustrated more clearly in. Figs. 1, 4t, 5 and 9, these connections consist of a worm 66 on the shaft 43 meshing with a worm gear 67 on the lower end of an upwardly extending flexible shaft 68, the upper end of which is provided with a spiral gear -(i9- meshing with a similar spiral gear -70 on the shaft 65.

The lower end of the flexible shaft -68--- is j ournaled in a yoke 7 1 which is pivotally hung upon the shaft 13, the upper end of said shaft being journaled in a yoke 72- which is journaled upon an eccentric portion of a rock shaft 73 having its ends journaled in a pair of forwardly pro jccting arms -7-il forming a part of the extension (34 of the oscillating frame G'2, the rock shaft -73 being provided with radially extending handles 75 by which it may be rocked to shift the gear 09 into and out of mesh with the gear 70 for stopping and starting the lensholder independently of the grindstone or reversing mechanism for the carriage -16-. The outer end of the shaft -65 is provided with a hand-wheel -76 by which the shaft 65 and parts operated thereby may be adjusted in the initial setting up of the machine.

The lens-holder (i3 comprises a pair of coaxial lens-clamping members -77 and 78-- arranged end to end and having their adjacent ends provided with suitable pads for receiving and retaining the lens or lenses between them. said lens-clamping members being operativcly connected to separate coaxial rotary spindles -79 and 80 to rotate therewith.

These spindles arc journaled in suitable bear1ngs 1n the lower portion of the 0801igears 81 being so constructed and arranged as to drive both of the spindles -79- and 80 in the same direction at one-half the speed of the secondary driving shaft 82 The adjacent ends of the shafts 65 and 82 are spaced apart and are provided with similar disks or crank arms 83 and 8-1 pivotally, but eccentrically, connected with each other by suitable means, preferably a link 85, for transmitting rotary motion from the main driving shaft 65+ to the secondary driving shaft 82 and causing the secondary shaft -8Q and lens-holder driven thereby to revolve in the same direction as the driving-shaft, but at different speeds during each revolution.

For example, in grinding an elliptical lens if the lens-holder is driven at the same rate of speed during each revolution, the edges adjacent the ends of the shorter axis will not grind down as rapidly as those adjacent the ends of the longer axis, due mainly to\the-difference in arc of contact with the stone. and also to difference in thickness of the lenses at these points, and in order to overcome this inequality in the speed of grinding and to cause all portions to be ground to the desired form at about the same time, the disks 83 and 8l and their shafts 65 and 82 are arranged and connected in such offset relation as to cause the lens to rotate with slower speed when grinding across the ends of the short axis than when grinding across the ends of the long axis. v

That is, the speed of rotation of the lens is greatest when grinding across the ends of the longer axis and is sufiiciently reduced or retarded when grinding across the ends of the shorter axis to effect a uniform grinding so that all portions will be finished at about the same time.

The spindle 79 is provided with an anti-friction end-thrust bearing 86 interposed between the hub of the gear -81- thereon and the adjacent outer end of the frame.

The lens-clamping member 77 is connected to its corresponding spindle -79- by means of a coupling ST having reduced ends which enter central sockets in the adjacent ends of the clamping member -77 and shaft -79-, respectively, as shown more clearly in Fig. 6, the coupling 87 being locked to the adjacent end of the shaft by means of a pin 8 8 to cause them to rotate together.

A lens pattern 89 is mounted upon the coupling -87 between its enlarged central portion and adjacent end of the clamping member 77' and together with said coupling member may be locked to rotate therewith by any suitable locking means, not necessary to herein illustrate or describe.

The clamping member 78 is provided with a central opening for receiving the adjacent reduced end of the spindle 80 to which it is locked to rotate therewith by means of a pin -90. I

The spindle 80 and its corresponding clamping member 78- are movable axially to clamp and release the lenses, said spindle being provided with an anti-friction end-thrust bearing 86, similar to the bearing 86, and interposed between a sleeve 91- on the outer end of said spindle and a set of coilsprings 92 in the hub of the adjacent gear 81, the springs serving to prevent excessive pressure of the lensclamping members 77 and 78 upon the lenses to reduce the liability'of breakage of said lenses.

Suitable means, operable at will, is provided for shifting the spindle -80 and its clamping member -78 axially and automatically locking it in any of its adjusted positions, said means consisting, in this instance, of an upright rock arm -93. arranged Within .the corresponding end of the frame 62 and pivotally mounted at its upper end upon a cross pin 9-fl and hav- 'ing its lower end bifurcated to extend partially around the spindle and provided with pins or lugs 95' engaging in an annular groove 96 in the sleeve -9l, the sleeve being held against endwise movement relatively to the spindle 80-- between the antifriction bearing 86- and a cap screw -97 on the outer end of said spindle, as shown in Fig. 6.

A rock shaft 97 is journaled at its opposite ends in the front and rear sides of the frame 62- some distance below and parallel with the pivotal pin 94 and extends through relatively larger openings 98 in corresponding sides of the rock arm 93-, the central ortion of the rock shaft being enlarged radially and provided with opposite upwardly and inwardly projecting cams or eccentric bearings 99 which engage contacts or pins -lOO- on superposed portions of the rock arm 93-, the cams 99 and pins -100 being so arranged as to cause the pressure of the pins -100- to act radially 0f the rock shaft 97- so as to automatically lock the rock arm in any position of adjustment.

One end of the rock shaft -97 is sccured in a bushing 10l, Fig. 8, which is journaled in the adjacent side of the frame -62' and extends to the outside thereof where it is provided with an operating handle 102 for turning the rock shaft in one direction or the other and thereby transmitting rocking motion to the lever -93- to effect a corresponding axial adjustment of the spindle 80 and the lens-clamping member -78.

Suitablemeans is also provided for automatically rocking the lower end of the frame 62- toward the grindstone to cause the lens to contact therewith, and for' this purpose a lever ''103 is pivoted at -10t to the outside of the upper portion of the shield 4. and is provided with a downwardly projecting arm 105 connected by a link 10 6- to an arm 107- on the -frame62, as shown more clearly in Figs.

' adjusted by means of a hand-piece 1l3,

said carriage being also provided with a suitable truing device 114. capable of being adjusted at will to keep the face of the grindstone smooth and true.

Operation.

grees, while each half of the lens which is driven at one-half the speed of the disk 84.- is correspondingly divided into eight (8) equal angles,'each representing an eighth turn of the disk 84.

As previously explained, the lens rotates onehalf revolution during each complete revolution of the disks, which, when connected in the manner shown and adjusted in certain relation to the lensholder, causes the lens to rotate at a maximum slower speed than its driving disk -84 when grinding across the ends of the short ax1s and at a maximum higher speed corresponding to that of the driving disk when traveling across the ends of the long axis, and 1t, therefore, follows that the two disks will be rotating at approximately the same speed and the lens at half that speed when grindi g across the ends of an axis substantially midway between the ends of'the short and long axis, or at an angle of about forty-five (45) degrees, relatively to said short and long axis.

This intermediate axis may be termed the neutral axis and is indicated by 0. \Vhen one end of the neutral axis is at the grinding point, the disks will be approximately in the position shown in Fig. 13, and which may be termed the starting position in which a direct line between the pivotal points of the links 85 and their respective disks is approximately parallel with a direct line drawn between the axes of the shafts -65- and -82-.

It will be remembered that although the driving disk 83 may be rotated at constant speed, the speed of the driven disk 84 will be variable, while the speed of rotation of the lens-holder and lens will be in constant ratio of one-half to one of the driven disk, and for convenience of description, the driven disk is indicated in full lines and the driving disk in, dotted lines, the radial lines indicating the relative arc of movement of the driving disk at the end of each successive eighth turn of the driven disk from its starting position.

For example, if the driven disk 81 is moved through the first eighth turn or through an arcof forty-five (45) degrees, as shown in Fig. 14, the driving disk 8 3 will have been moved through an arc of approximately fifty-one (51) degrees, during which the grinding point of the lens will have been moved from one end of the neu* tral axis, or zero, one-sixteenth (1 g) of a turn or one-eighth of a semi-ellipse toward the corresponding end of the short axis, showing that the driven disk 8l has been retarded six 6) degrees behind that of the driving disk with a result that the speed of movement of the lens has been correspondingly retarded.

In like manner as the driven disk is moved through the next succeeding eighth turn or are of ninety (90) degrees, the driving disk --83 will have moved through an arc of one hundred and seventeen (117) degrees, during which the lens will have moved another sixteenth turn, bringing the end of the short axis at the grinding point and showing that the driven disk has been retarded twenty-seven (27) degrees behind that of the driving disk during the second eighth turn, as shown in Fig. 15, with a corresponding retardation of the lens a.

During the third eighth turn of the driven disk -84, as indicated in Fig. 16, the driving disk will have been moved through an arc of one hundred and ninety-three (193) degrees, showing that the driven disk has been retarded behind the driving disk fifty-eight (58) degrees with a corremum retardation across the end of the short axis of the lens where it is most desired.

It will be noted that the speed of movement of the driven disk progressively reduces through the first, second and third eight-h turns, and that it begins to increase during the fourth eighth turn, or from the position shown in Fig. 16 to that shown in Fig. 17.

In Fig. 18, it will be seen that this increased speed of the disk 84 continues during the next eighth turn in whlch the driving disk 83 will have been moved I through an arc of approximately two hundred and sixty-one (261) degrees, showing that the retardation of the driven disk 84 is approximately thirty-six (36) degrees.

In the next eighth turn shown in Fi 19, the difference will be twenty-eight 528) degrees ',Fig. 20 four (4) degrees, showing that the "speed of the driven disk is gradually building up to that of the driving disk which it equals on the last ei hth turn, or in passingfrom the position s own in Fig. 20 to that shown in Fig. 13.

During thiS complete revolution of the disks 83 "and,84, the lens will have been moved from the zero position at one end of the neutral axis to the zero position at the opposite end of such axis, the operation being repeated during the next revolution of the disks, said operations recurring until the lens is ground to the desired form and size. 4

This differential speed motion is particularly etlicient in finishing the grinding operation of all portions of the lens at practically the same time, but it is evident that other means for producing this differential motion may be devised without departing from the spirit of this part of my invention, and, therefore, I do not wish to limit myself to the construction shown. I As the lens is rotated against the grindstone, it produces a. recurrent oscillation of the frame 62 about the axis of its pivotal pins 61 which are alined with the meeting faces of the gears 69- and 70, as shown more clearly in Fig. 6, the object of which is to maintain a uniform rotation of the driving shaft -(35 and its disk 83'-, as otherwise the oscillation of the frame wouldcause more or less interruption or unsteadiness in the rotation of said shaft and disk and parts driven thereby.

Another important feature of the invention consists in the means, as the screws 5$), for adjusting the arms 55 to vary the length of travel of the carriage -l6- at will.

It is also evident that when it is desired to open and close the lens-clamping jaws, it

' is simply necessary to shift the lever 102- by hand in one direction or the other, it being automatically locked in any position of adjustment by the engagement of the pins l00 with the bearing members 99-.

In machines of this character, the pattern and its support are usually provided with means for placing them in but one fixed relation which, as previously explained, conforms to a certain position of the disks 83 and 84 so that in placing the lenses in the machine for grinding, it is only necessary to the pattern.

The grinding operation may then proceed in the manner described without further attention from the attendant until the lens is ground to the desired size and form as determined by thepattern and the position of its back-rest relatively to the plane of grinding which may be regulated by any wellknown form of adjusting device, as -113- What I claim is: 1. In an edge-grinding machine for elliptical lenses, the combination with a grinder, of a rotary lens-holder, and means for roproperly register them with .tating said holder at such diflerent speeds during different parts of each revolution 'as to cause all portions in the periphery of the lens to travel against the grinder at-such v a rate of speed that all portions of said periphery shall be completed at practically the same time and means for maintaining the periphery of the lens against the grinder.

2. In a machine for grinding the edges of lenses having axes of diflerent lengths, the combmation with a grinder, of a rotary lensholder, and means for rotating said lensholder under gradually diminishing speed as the point of contact of the lens with the grinder passes from the end of the longer axis toward the end of the shorter axis.

3. In a machine for grinding the edges of lenses having axes of different lengths, the combination with a grinder, of a rotary lensholder, and means for rotating said lensholder under gradually decreaslng speed as the point of contact of the lens with the grinder passes from the end of the longer axis toward the end of the shorter axis.

4. In a machine for grinding the edges of lenses having axes of different lengths, the combination with a grinder, of a rotary lens-holder, and means for rotating said lensholder under gradually increasing speed as holder' including eccentrically connecteddriving and driven members rotatin in the same direction-about parallel axes offset one from the other.

6. In an edge grinding machine for lenses, the combination with a rinder, of coaxial rotary lens-clamping mem ers and means for forcing one of said members endwise to-' ward the other member including cooperative rockers movable about parallel offset axes, and bearing one against the other at opposite sides of a direct line-between said axes.

7. In an edge grindingmachine for lenses, the combihation'witha grinder, of coaxial rotary lens-clamping members, driving shafts therefor, a rocker arm pivoted to swing in a plane parallel with one of said shafts, connections between said rocker arm and shaft'to' move the latter axially, and a manually-operated rocker in operative engagement with;.the rocker arm for rocking the same in opposite directions.

8. In an edge grinding machine for lenses, the combination with a grinder, of coaxial rotary lens-clampin members, driving shafts there or, a rocker arm pivoted to swing in a plane parallel with one of said shafts and provided with bearings at opposite sides of its pivot, and a manually- .operated rocker having cam faces at opposite sides of its axis engaging said bearings.

9. In an edge grinding machine for lenses, the combination with a grinder, of coaxial rotary lens-clamping members, separate driving shafts therefor, one of the shafts being movable axially, means including gears on the shafts for driving the same, one of the gears being movable axially with its shaft, an end-thrust bearing for the axially movable shaft, and yielding connections between the end-thrust bearing and adjacent gear.

10. In a machine for grinding the edges of lenses, the combination with a rotary grinder, a carriage movable parallel with the axis of the grinder, a frame pivotally mountseparate separate ed on the carriage to swing toward and from to the first-named shafts, said means including cooperative rotary members revolvin in the same direction about parallel axes oi fset one from the other, and means for connecting the last-named members to each other.

11. In a machine for grinding the edges of lenses, the combination with a rotary grinder, a frame pivoted to swing about an axis parallel with that of the grinder, a rotary lens-holder mounted on the frame parallel with and some distance to one side of said axis, and driving means for said lensholder including a pair of gears meshing at a point in approximate alinement with said axis.

12. In an edge-grinding machine of the character described, the combination with a grinding element, a work-holder, and a swinging support therefor, of means for rotating the workholder including a pair of rotary driving members contacting at a point in approximate alinement with the axis of movement of said support.

13. In an edge-grinding machine for elliptical lenses, the combination with a grinding element and a rotary lens-holder, of means for rotating said holder so as to cause the portion of the lens adjacent the ends of the short axis to travel 'against the grinding the edges of the lens at the ends of the shorter axis to travel past the grinding point at a slower rate of speed than that of the edges at the ends of the longer axis past the same point. a

15. In an edge-grinding machine for elliptical lenses, the combination with a grinding element and a rotary lens-holder, of means for rotating said holder at such variable speed as will maintain an approximately constant speed of all portions of the periphery of the lens past the grinding point.

In witness whereof I have hereunto set my hand this 15th day of May, 1916.

ELI MAYNARD LONG.

Witnesses:

ALBION WV. NEWELL, H. E. CHASE.

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