US2159620A - Lens grinding and polishing machine - Google Patents

Description

y 23, 1939- E. M. LONG 2,159,620

LENS GRINDING AND POLISHING MACHINE I Filed July 26, 1937 :5 Sheets-Sheet 1 45' 27 2.9 /3 ,2 4 2a 30 INVENTUR May 23, 1939. E, M NG 2,159,620

LENS GRINDING AND POLISHING MACHINE Filed July 26, 1937 3 Sheets-Sheet 2 f 2 J 37 39 38 K g 6' l I 42 5 f -34- 4 r j 2' )2 .54; I 32 32 6 60 E f, Em

J 2 2a m 29 0 m4- 65 May 23, 1939. E M. LONG 2,159,620

LENS GRINDING AND POLISHING MACHINE Filed July 26, 1957 3 Sheets-Sheet 3 Patented May 23, 1939 LENS GRINDING AND POLISHING MACHINE Eli Maynard Long, Geneva, N. Y., aaslgnor to Sharon Optical Company, Inc., Geneva, N. Y., a corporation of New York Application July 26, 1937, Serial No. 155,8 86

12 Claims. (Cl. 51-160) This invention relates to improvements. in a lens grinding and polishing machine.

The invention-pertains more particularly to a machine for grinding and polishing the surfaces of toric lenses and is an improvement upon a machine of the type forming the subject-matter of my Patent r'ifc. 1,709,943, issued April 23; 1929.

In the machine of'that patent, the movable element (specifically the lens holder), of a grinding 0 and polishing couple consisting of a lens holder and a lap, is actuated by the combined action of tworeciprocative movements operating indirections at substantially right angles to each other,

one reciprocative movement operating substant'i ally parallel with the base-axis of the lens (usu ally called the lengthwise stroke), and the other reciprocative movement operating substantially parallel with the cylinder axis of the lens being ground (usually called the cross stroke); and a continuous variation or break-up (so-called third movement) is introduced into the latter one only of the'reciprocative movements, so that I the resultant path of movement of the movable element of the grinding and polishing couple is a series of curvilinear strokes, and said movable element goes through a comparatively large number of strokes before completing a cycle of operation and repeating its pattern of movement.

The efllcacy of a machine of the above mentioned type is inherently limited to a certain extent for the following reasons. In the first place, each stroke must be relatively short in length, owing to the limited area of the surface of the grinding lap engaged by the lens which necessarily limits the length of the stroke of each of the two reciprocative movements. Secondly, the movable element, which is the lens holder in the machine of my patent,- must move through a different path on each successive stroke, and the change of path must be sufllciently great to prevent any minute inaccuracies occurring in the surface of the lap being reproduced on the lens. In other words, the lens must not be moved back and forth across the lap a large number of times 46 along substantially the sameline, or else a defective or inaccurate portion of the grinding surface of the lap will produce a zone of aberration in the lens surface. If, on the other hand, the change in the path of movement of the lens be- I0 tween successive strokes is made too great, the

affected thereby. As a result of these inherent limitationsmachines of this type, including the machine shown in my above mentioned patent,

will produce only a relatively low percentage of firstquality lenses.

The main object oi'this invention is to produce an improved lens grinding and polishing machine wherein the relative movement of the lens and the grinding lap is produced by two reciprocative movements operating substantially normal to each other with means associated with both of said reciprocatlve movements and coacting therewith to break-up or vary the same, thereby producing a maximum change between successive paths of travel of the lens with respect to the 15 grinding lap, while at the same time greatly increasing the duration ofv each cycle of operation, so that a lens will not be moved twice through the same path during the time ordinarily required to grind or polish a surface thereof. 20

Another object of this invention is to provide simple and efficient means, cooperating with the reciprocative movement operating in a direction substantially parallel with the base axis of the lens, or lengthwise stroke, for producing a fourth 26 movement by which a variation will be introduced into said lengthwise stroke, whereby a variation in the point of reversal of the movable element of the grinding and polishing couple from the normal position of reversal of movement there- 30 of, resulting from the combined variable reciprocative movements, is attained during the progressive grinding and polishing of a lens surface for the purpose of preventing, to a greater extent than heretofore, the formation of aberrations, 35 waves and distortions in the surface of the lens incidental to the reversalof the movable element at one and the same point.

A more specific object of the invention is to provide means whereby the extent of the length.- 40 wise stroke of the movable element of the grinding and polishing couple, produced by that reciprocative movement operating substantially parallel with the base axis of the lens in combination with the fourth movement, may be quickly and easily varied for lenses of different curvatures and types.

A further object of the invention resides in providing a novel means for producing a break-up in the stroke which may be applied to either or both of. the reciprocative movements.

In other words, I'have endeavored to produce a slow continuous change in'the length of the relative movement of a lens and the grinding and polishingsurface throughout successive strokes of the cycle of operation over an extended or indeflniteperiod, and thus eliminatethe formation of lines or waves in the lens surface which may cause a zone of aberration.

Other objects and advantages relative to the form and operation of the parts of the machine will more fully appear from the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a top plan, partly in section, of a lens grinding and polishing machine embodying certain features of this invention, with the cover removed to show the interior parts.

Figure 2 is a vertical transverse sectional view taken on line 2-4, Figure 1, showing the cover in place and the upper portion ofthe means for producing and maintaining pressure upon the lens carrier arms broken away.

Figure 3 is a detail vertical longitudinal sectional view, through the lower portion of the machine, taken substantially in the plane of the line 8-3, Figure 1.

Figure 4 is an enlarged detail horizontal sectional view taken substantially in the plane of the line 4-4, Figure 3, and illustrating my novel mechanism for producing a break-up in the stroke used as a fourth movement mechanism, that is to say, applied to the drive means for producing reciprocative movementof a lens carrier element in a direction substantially parallel with the base axis of the lens.

Figure 5 is an enlarged detail sectional view taken on line 5--5, Figure"4.

Figure 6 is a detail horizontal sectional view, partly in elevation, of-a modiflcation in which my novel break-up mechanism is connected to the inner end of the main drive shaft, and is used in the place of the third movement mecha nism shown connected with said shaft in Figures 1, 2 and 3, that is to say, for effecting a slow continuous change in the normal point of reversal of the movable element of the grinding and polishing couple in a direction substantially parallel with the cylinder axis of the lens.

Figure 7 15a detail sectional view taken on line 'I-I, Figure 6.

view taken in producing said movement under certain predetermined adjustments.

Figure 14 is a diagrammatic view illustrating the action of the drive mechanism shown in Figure 6 for producing the cross stroke or movement of the lens supporting element over the grinding face in directions substantially parallel with the cylinder axis of the lens under certain predetermined adjustments.

Figure 15 is a diagrammatic view illustrating succeeding strokes of the lens over the grinding surface of the lap, as produced by my novel mechanism when set in the position indicated in Figures 11 and 12.

Figure 16 is a diagrammatic view illustrating succeeding strokes of the lens over the grinding surface of the lap as produced by the motion break-up mechanism shown connected to the main drive shaft in Figures 1, 2 and 3.

The machine, as illustrated in the drawings, has the greater portion thereof of usual construction and operation, being similar to that shown in my above mentioned Patent No. 1,709,- 943. The machine is shown as being provided with a casing I which carries a pair of lens surface grinding and polishing couples. Each couple comprises a lap supporting element 3 fixedly secured to the front side of the casing vI, and a lens actuating or pressure arm 4 which extends from the interior of the casing l outwardly through a slot 5 provided in the front wall of the casing to a position over and beyond the corresponding lap supporting element 8.

I A main drive shaft 8 is journaled in suitable bearings 1 and I provided in the casing I to rotate about a horizontal axis. The shaft is driven from a pulley 8 mounted thereon exteriorly of the case, said pulley being adapted to be operated by a belt from any suitable source of power,- not shown.

As illustrated in Figures 1, 2 and 3 of the drawings, the inner end of shaft 8 is provided with an eccentric crank pin in adapted'to' rotate bodily about the axis of the shaft. A connecting rod or pitman H is rotatably mounted at one end upon the crank pin l0, while-the lower end of the connecting rod is provided with a stud II which extends laterally therefrom in a horizontal plane substantially parallel with the axis of the pin It).

An eccentric l8, journaled upon the stud I2, is provided with a worm gear l4 at one end thereof which is in meshing engagement with a worm l5 secured to the lower end of a vertically disposed shaft II; which, in turn, is 'journaled in suitable bearings I! and I! provided on the connecting rod Ii. The shaft l6 has secured to the upper end thereof a worm gear 28 which is in meshing engagement with a worm 2| secured to the outer end of the crank pin III. A yoke member 23 is rotatably mounted upon the eccentric l8 and is adjustably connected to a curved portion 24 of an arm 25 by a set screw 26. The arm 25 is secured at one end, by a set screw 21, to the central portion of a rock frame 28 which is rotatably connected, by pivot pins 29, to upwardly extending posts or lugs 30 projecting from the bottom of the case I, so that the frame 28 rocks about a horizontal axis extending substantially parallel with the axis of the drive shaft 6 and arranged in a plane at one side of said shaft. The curved portion 24 of the arm 25 is arranged concentric with and has its center of curvature approximately in the axis of the drive shaft. 8, so that adjustment of the yoke 23 longitudinally of the arm 2i for varying the degree of rocking movement of the frame 28, will produce a minimum amount of tilting movement of the arm 2! and frame 28. It will be observed that the action of the eccentric l8 and its associated drive shaft l8 and gearing, is to continuously vary the effective length of the connecting rod ll connecting the crank pin l0 and the curved arm 25, so that, for a given setting of the adjustable yoke 23, a constant angular rocking movement of the frame 28 will be produced, but the position of the rocking movement will vary slightly and continuously.

The rock frame 28 carries a pair of upright supports 32 arranged in spaced relation to each other longitudinally of the frame. Each of the supports 32 is pivotally connected to the frame 28 at opposite sides of the axis of rotation of said frame by pivotal pins 33. The supports 32 extend upwardly from the pivots 33 and each has the upper end thereof bifurcated to receive'adjacent end portions of a floating frame 34 which extends in a horizontal plane above the frame 28 and is pivotally connected to the supports 32 by pivotal pins 35. It is thus seen that. the floating member 34 constitutes a connecting link between the upper end of the supporting members 32, whereby the supports" will be simultaneously rocked in reverse directions, about the pivots 33, as the floating frame 34 is reciprocated lengthwise in a manner presently described.

A pair of reversely arranged substantially L- shaped arms 31 and 38 arepivotally mounted at 38 and 40, respectively, upon the floating frame 34 to swing about coaxial axes parallel with the axis of the frame 28 and drive shaft 5, the L- shaped arms 31 and 38 being movable vertically independently of each other for permitting independent operation of the hereinbefore mentioned lens carrying, arms 4 which are pivoted, at 42, to the L-shaped arms 31 and 38, respectively. The pivots 42 of each lens operating arm 4 are disposed in approximately the horizontal plane of, and nearly coaxial with, the pivots 35, as shown in Figures 2 and 3, so that arms 4 may swing about parallel axes at substantially right angles to the axis of the rock frame 28 anddrive shaft 6 to compensate for varying positions of their respective lens holders 43 when moving across the face of their corresponding laps 44.

The construction and'operation of the .mechanism thus far described is substantially the same as that shown in my Patent No. 1,709,943, and is adapted more particularly for producing reciprocative movement of the lens supporting arms 4 in directions substantially parallel with the shorter or cylinder axis of the lens. The mechanism which includes the novel features of this invention, forproducing reciprocative movement of the lens supporting arms 4 in directions substantially parallel with the longitudinal or base axis of the lens, will now be explained.

The main drive shaft 6 is provided with a worm 45 positioned intermediate the bearings 1 and 1. The worm 45 meshes with a worm'gear 46 rotatably mounted upon a fixed shaft 41 secured to the casing beneath the drive shaft by a set screw 48, Figure l. A yoke 50, connected with the worm gear 46 byarms 5|, is rotatably mounted on shaft 41. The arms 5| cause the yoke 50 to rotate in unison with the gear 46 and form an intervening space for receiving a pair of collars 52 which are secured to the shaft .41 to hold the gear 45 and yoke 50 against axial movement with respect to shaft 41. A crank pin 54 is journaled for angular adjustment in the yoke member 50 at one side of and parallel with the stationary shaft 41. The crank pin 54 is held in different positions of angular adjustment by means of a clamping screw 55 engaged in a diametrically extending threaded aperture in the crank pin 54 and which extends outwardly from the crank pin through an elongated slot 55 provided in the adjacent portion of the yoke 50 to permit relative rotary adjustment of the screw. Mounted in the threaded aperture in the crank pin 54 is a friction block 51, positioned at the inner end of the screw 55, adapted to be brought into frictional contact with the peripheral surface of the wall of the aperture 50' receiving the crank pin 54 for releasably maintaining said crank pin against rotation relative to the yoke 50.

The crank pin 54 is provided with a reduced eccentric extension 54' which is substantially parallel with the axis of the crank pin. Rotatably mounted upon the extension 54' is an eccentric sleeve 59, upon which is rotatably mounted a drive sleeve 58 which, in turn, is pivotally connected, as at 5|, to one end of a pitman 62, having its other end connected by a universal joint 63 to the floating frame 34 (see Figures 3 and 4). The outer end of the eccentric sleeve 55 has connected therewith a gear 65 which, in this instance, is of greater diameter than the sleeve 58 and coacts with an annular flange 56, provided on the crank pin 54 at the inner end of the extension 54', for' maintaining the drive sleeve 50 against axial displacement. The eccentric sleeve 58 is maintained against axial displacement, relative to the extension 54', by a bracket 61 secured to the outer end'portlon of the extension 54', as shown in Figure 4.

Journaled in the bracket 51 is a stub shaft 58 arranged at one side of the extension 54' in parallel relation therewith. The shaft 58 extends outwardly at both ends beyond the sides of bracket 51 andhas secured to one end thereof a pinion 69 which is in meshing engagement with the gear 65. The other end of the shaft 58 has secured thereto a gear which is in meshing engagement with a pinion 1| rotatably mounted upon a reduced portion 54" of the extension 54 and which is arranged in coaxial relation with said exten-- sion 54'. To the outer end of the pinion 1| is secured an arm 12. This arm 12 is fixed to the pinion 1|, extends radially therefrom and is provided with an elongated slot 12 which slidably receives therein a holding pin 13 secured to the adjacent front wall of the casing I, as shown in Figure 9. Pin 13 and slot 12 are so related to each other that arm 12 may freely move longitudinally as the gear 1| revolves about'the axis of shaft 41.

Thelens or lenses to be ground may be fastened, in any suitable manner, to the underside of the lens holder or block 43 for reciprocative movement across and upon the upper face of the lap 44, carried by the corresponding supporting element 3 for grinding and polishing purposes. It will be understood that the outer end portions of lens actuating arms 4 may each be moved toward and from the lap'supporting elements 3 independently of each other, by any suitable means, to permit the removal and replacement of the lens holder 43, while the lens carried by the holder may be yieldingly held in pressure engagement with the lap 44 by any suitable means. as by an upright pressure rod and a spring 11, portions of which are shown in Figure 2.

It will now be observed that when the main drive shaft 5 is being rotated, a lens, carried by one of the arms 4 in pressure engagement with the corresponding lap 44, will be moved across the grinding surface of the lap with a curvilinear movement compounded of two reciprocative movements operating at right angles to each other and two break-up movements, each of the latter movements being associated with a respective one of the reciprocative movements.

To explain more explicitly, the rotation of crank pin l8 about the axis of shaft 5 will produce a rocking movement of the frame 28 about the pivots 29. This rocking movement of frame 28 will produce a corresponding reciprocative movement of the upper portion of the supports 32 and the arms 4 carried thereby in a direction substantially parallel with the cylinder axis of the lens mounted on said arms, inasmuch as the axes of pivots 29 extend in a plane substantially normal to the cylinder axis of the lens. At the same time, the rotary movement of eccentric 13, produced by the gear members 2| and 25, shaft and gear members l5 and I4, will cause a relatively slow independent movement of the yoke 23 and arm 25 in the direction of the length of the connecting rod H, and this independent movement is transmitted to the arm 4 and lens actuated thereby through the frame 25, supports 32, frame 34 and arms 31 and 38, thereby caus-.

Y ing a' continually varying effective length 'of the'connection between the driving shaft 5 and arm- 25 which, in turn, causes a continually changing scope and field of action of the. lens holder and lens carried thereby across the grinding surface of the lap, as indicated in Figure 16, in the same manner as shown and described in my Patent No. 1,709,943.

In my-novel drive mechanism, the lens actuating'arms 4 and the lens connected therewith are re'ciprocated longitudinally of the lap 44 by the rocking of -.frame 34 and supports 32 about the axes of the pivots 33 and 35. produced by the crank pin 54 as the same is rotated about the axis of shaft", through the medium of the drive sleeve 60 and crank arm 52. During this rotary movement of the crank pin 54, the length of the lengthwise stroke of the floating frame 34 will be constantly changing due to a continually varying effective length of the crank arm connection between the axis of shaft 41 and the connecting rod 52. This continuously varying effective crank arm length-is produced by the rotation of eccentric sleeve 59 upon the crank pin extension 54,

shaft 41; the points 54 represent the axis of the crank pin 54 mounted in the yoke 50;.the points 54' represent the axis of the crank pin extension 54'; and'the points 59 represent the axis'of the eccentric sleeve 59;'the two sets of points 54, 54' and 59 in each figure being represented in different positions 180 apart; The full and broken .lines 52 represent the connecting rod 52 in its extreme forward and back.positions. Line 34 represents'the frame 34 and lines 32 represent the supports 32. The circle X represents the path of movement of the crank pin 54 about the axis of-the shaft 41, while the circle ,Y represents the path of movement of the axis of the crank pin extension 54 about the shaft 41. Circle X indicates the possible path of movement of the axis of-th'e extension 54' during adjustment of said crank pin within the yoke 50, while the circle Y represents the path of movement of the axis of the eccentric sleeve 59 about the axis of the crank pin extension 54 during the rotation of the sleeve upon the extension.

It will now be evident that when the crank pin' 54 is adjusted relative to the yoke 50 to obtain the maximum degree of travel of the crank pin extension 54 about the axis of the shaft 41, as shown in Figures 11 and 12, the-lens carrier pin 4' connected with the lens carrier arm 4 will be moved a maximum distance'over the grinding surface of the lap 44 as the crank pin 54 revolves about the shaft 41-. I

It will also be obvious that inasmuch as the eccentric sleeve 59 is being constantly rotated at a relatively slow rate of speed, the longitudinal center of the sleeve 55 will be slowly rotated about the axis of the extension 54', thereby constantly varying the effective length of the crank connection between the axis of shaft 41 and the connecting rod 52, and causing each arm 4 to move through gradually varying distances within the limits shown by the full and broken lines 4 in Figure 11. In other words, the arm 4 will move between the positions obtained by the maximum degree of throw produced by the combined action of the crank pin and eccentric sleeve, as shown in Figure 11, and the minimum degree of throw as shown in Figure '12.

The setting of the crank pin 54 to-obtain the maximum degree of movement of the lens carrier arm 4 is utiiized with a lens having a substantially flat surface or one in which the'curve of the surface being ground has arelatively long radius. When the surface of the lens being ground has a relatively short radius, the crank pin 54 is adjusted in the yoke 55 to bring the axis of the extension 54' thereof into relatively close relation with the axis of the shaft 41. When the crank pin 54 is thus adjusted to obtain the minimum degree of action produced by the crank pin, as indicated diagrammatically in Figure 13,

the carrier arm 4 will obviously have a much less degree of movement than with the previously described adjustment of the crank pin.

It'wifl be observed, however, that owing to the driving connections between thecrank pin extension 54' and the eccentric sleeve 59 and the relatively slow speed of rotation of the eccentric sleeve thus produced, the position of the point of connection between the arm 52 and sleeve 60 is continuously but slowly changing with respect to the axis of extension 54' and t at at every revolution of the eccentric 59 upon he extension bility ofscoring or otherwise injuring the lens as the lens is moved longitudinally of the base curve. of the lap 44 by any errors or imperfections in the grinding surface of the lap.

The above described action of the crank pin ex- .tension 54' and eccentric sleeve 59, upon the frame 34 andarms 4, is equally true when,the crank pin 54 is adjusted to obtain the minimum degree of travel of the lens across the lap 44, as shown in Figure 13, wherein.the minimum and maximum amount of travel of an arm 4, for such adjustment, is indicated at aand b respectively.

In Figures 6, 7, 8 and 10, I have illustrated the use of my novel break-up mechanism-for the purpose of producing the break-up movement of the cross stroke, that is to say, applied to the means for reciprocating the floating frame 34 in directions parallel with the cylinder axis of the lens and lap. In this structure, the drive shaft 8 has the crank ,pin 10 thereof rotatably supporting the eccentric sleeve 59 and gear 55, while the bracket 61 is secured to the outer end of the crank'pin Hi. This bracket 8 rotatably carries the shaft 68,

'which-inturnhas the pinion '69 secured to one end anId-thegear' 10 securedto the other end thereofflThe pinion 69 is in meshing engagement withthe gear 55while the gear 10 is'in meshing engagement'with the pinion H which is 'J'ournaled on an extension Ifl'provided on the outer end of the crank'pin ID in coaxial relation therewith.

The pinion II is maintainedgagainst rotation during the rotation of the extension l about the axis of the shaft 6 by a pair of links 80 which 'are pivotally connected, as at- 8|, Figure 10, to each other. One of the links is pivotally connected,

as at 82, to the rear wall of the casing l,.while the other link is fixedly secured to the pinion H.

Rotatably mounted upon the eccentric sleeve 59 is a connecting rod 84 which extends down- 25 the outer end'thereof a yoke 86, similar to the a set screw 81.

through the supports 32 yoke 23 shown in Figure 2. This yoke 06 is provlded with an aperture extending therethrough substantially normal to the stud for receiving the curved end portion 24 of the arm 25. The yoke is adjustably secured tothe arm 25 by Inthe construction shown in Figure 6,-the effective lengthqoi' ,the crank arm connection between the axes of shaft 6 and connecting rod 84 is constantly changing,- as illustrated diagrammatically in Figure"14, due to the continuous but relatively slow rotation of the eccentric sleeve 59 upon the crank pin III, as the crank pin l0 revolves about the axis of the shaft 6. This continuous rotation 'of eccentric sleeve 59 upon crank pin I0 is caused b y the rotary movement transmitted to the gear ifi by pinion 69 asex'plained hereinbefore for the structure shown in Figure 4. This gradual increase or decreaseln the effective length of the crank arm connectionbetween thfe axis of shaft 8 and rod84 producesa corresponding variation in the'length oftlie stroke thereof and the angular extent of th rocking movement of the frame 28, which n'rent is transmitted raine 34 and arms 31 and 38 to the lens actuatingj'arm's 4 and the lens actuated'thereby. V

' In other words; when the stud 85 has been moved to its extreme up position by the combined action of the eccentric sleeve 59 and the crank l0, through the medium of the connecting rod 84, in which position the high point of the eccentric sleeve 59 is directly over the axis of the stud 85, then the point of connection between the arm 25 and yoke 86 will assume a position at A, Figure 14, at the upper limit ofv the movement of the stud 85. When the crank pin H) has been moved 180to its lowermost position and the eccentric: sleeve has been rotated so that the longitudinal center thereof lies directly below the axis of the Stud 85, then the-point of connection between the 'arm 25 and yoke 86 will assume a position at A at theextreme lower position of its movement; These'extreme positions of the 'pointof connection between the yoke 86 and the driving connectionsbetween the crank pin l0 and the eccentric sleeve 58 and the relatively slow speed'of rotation of said sleeve produced by said connection, the effective length of throw of crank pin I0 is continually but slowly changing. At every changing of the length of this throw, a corresponding change in the length of the cross stroke of arms 4 is produced even as the length of the lengthwise stroke is continually changing when my novel motion break-up mechanism is mounted on crank pin 54 as explained hereinbefore and as illustrated in Figure 15. 7

It will now be clear that when my novel breakup mechanism is applied to the means for recip'rocating the lens longitudinallyof' the grinding surface of the lap, as shown in Figure 1, the center of each reciprocative stroke'will be substantially coincident with the minor axis of the lap as illustrated in Figure 15, wherein line NN represents the minor axis of the grinding lap and lines M represent succeeding strokes of a pin 4' lengthwise of the lap. Also. it will be understood that when my novel break-up mechanism is applied to the means for producing the cross stroke, or for moving the lens transversely of the grinding surface of the lap, as shown in Figure 6, it will likewise produce strokes which are of varying. lengths, and wherein the centers of the strokes, as indicated by line NN, Figure 15, extend in a straight line, are substantially coincident with the major axis of the lap.

It therefore follows that the combination of the two circular movements produced by my novel break-up mechanism with the two reciprocative movements will produce a continuous change in the position of the ends of the succeeding strokes of the lens across the grinding surface of the lap due to the continually changing lengths of both the -lengthwise and cross strokes.

If, however, the motion break-up mechanism applied to the cross stroke is substantially the same, as that shown in my Patent No. 1,109,943, and illustrated in Figures 1 and 2 of this applicatiohjthe general direction of movement of the lens across the face of the lap is through a more or less serpentine path, as illustrated in Figure 16L0f the drawings wherein the line O-O represents the major axis of the grinding lap, lines M represent succeeding cross strokes of a pin 4' upon the lap, and line PP represents the center line of each stroke. These differences in the character of the variations introduced into the lengthwise and cross strokes Whenmy novel break-up mechanism is applied to the drive pin 54: and the break-up mechanism shown applied to the crank pin 10 in Figures 1 and 2. are due to the fact that in the break-u mechanism shown in Figure 4 the rotation of the eccentric sleeve 59 causes a change in the effective throw of said sleeve and has the effect of continually increasing or decreasing the eccentricity of the crank pin 54 with a resultant increase or decrease in the length of the stroke produced by the combined action of the eccentric sleeve 59 and crank pin extension 54'. illustrated by Figure 15. In the break-up mechanism connected with crank pin Iii, Figures 1 and 2. the rotation of the eccentric l3 produced by the gear members 2| and 22, shaft l6 and gear members !5 and M. has the effect of continuously increasing or decreasing the lengthtof the connecting rod ii, while main taining a substantially uniform length of stroke because the throw of eccentric I0 remains constant. A corresponding change is thus produced in the position but not in the length of the cross stroke of arms 4, as illustrated by Figure 16.

It will be seen from the foregoing that the resultant effect produced by my novel break-up mechanism, when used in connection with the lengthwise stroke in combination with the breakup mechanism shown in Figures 1 and 2, connected with the cross stroke, upon each of the arms 4 and the lens holder actuated thereby will be to reverse their motion at constantly changing points during succeeding strokes while the general field of operation thereof is maintained substantially constant. This is due to the lengths of the longitudinal strokes being constantly varied, as shown in Figure 15, while the length of the cross strokes are maintained substantially equal, but the general field of operation thereof is constantly changing as indicated in Figure 16. In other words, whether my novel break-up mechanism is used in connection with the cross stroke, as shown in Figure 6, or the break-up mechanism, shown in Figures 1 and 2, is associated with the cross stroke, the combination of either of these movements with the break-up mechanism, shown connected with the lengthwise stroke. when combined with the two reciprocative movements, will produce a continuous change in the position of reversal of movement of the lens across .the grinding surface of the lap during each succeeding stroke without materially decreasing the length of the stroke produced by the combined action of the two reciprocative movements. At

the same time the cycle of operation or the period drawings, each cycle of operation actually con.

tinues without repeating any stroke for several hours of operation, while the operation of the machine of one grinding or polishing operation seldom exceeds twenty minutes. n the other hand, in the machine of my Patent l lo ,7 9, 4 in which only the variation produced by the coaction of gears l4, I5, 20 and 2| and eccentric sleeve IS .in connection with the cross reciprocating movement is employed, the cycle of operation repeats about once every minute or in about every 450 revolutions of the drive shaft 6. Furthermore my novel break-up mechanism is applicable for introducing a variation into either the cross stroke or the lengthwise stroke or both, but'this is not true of the break-up mechanism of my said patent which is applicable only in'connection with the cross stroke as illustratedtherein. It is thus evident that the efficiency of the machine of the present invention is materially increased over that of said patent and a resultant increase in the percentage of first quality lenses, as that term is understood in the optical industry, is obtained with the machine of this application.

Although the construction and operation of the novel features of the mechanism above described are particularly simple, practical and eflicient, I do not wish'to be limited thereto as it is evident that various changes may be made in the detail construction without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. In a lens grinding and polishing machine having a lens grinding element and a lens holding element mounted in cooperative relation with each other, in combination, operating mechanism for producing relative movement of said elements to effect grinding of the lens carried by the holding element comprising two operating members, two drive means, one for each operating member, means operatively connecting said drive means with the operating members for producing reciprocative movement of each operating' member in directions substantially normal to the reciprocative movement of the other operating member, each of said connecting means including a break-up mechanism adapted to cause variations in the reciprocative movement produced by said connecting means to effect operation of the operating member through continuously changing paths, and means for simultaneously operating said drive means.

2. A lens grinding and polishing machine as in claim 1 wherein at least one of said break-up mechanisms is of such'a character that the action produced thereby is to constantly vary the length of each succeedingreciprocative stroke of the operating member operated thereby.

each other, in combination, operating mechanism for producing relative movement of said elements to effect-grinding of the lens carried by the holding element comprising two operating members, two drive means, one for each operatng member, means operatively connecting said alive means with the operating members for producing reciprocative movement of each operating member in directions substantially normal to the reciprocative movement of the other operating member through continuously changing paths, and means for simultaneously operating said drive means, one of said connecting means including a mechanism for constantly varying the length of each succeeding reciprocative stroke of the member operatedthereby while maintaining the center of said strokes substantially constant with respect to a plane extending therethrough normal to said strokes and the other connecting means including mechanism for constantly varying the position of the center of each succeeding stroke of the member actuated thereby lengthwise of the strokes while maintaining said strokes of the member at a substantially uniform length.

5. A lens grinding and polishing machine as in claim 4 having means adjustable at will connected with said operating mechanism for varying the amount of movement of each operating member.

6. In a lens grinding and polishing machine having a lens grinding element, a lens holding element, and operating means comprising relatively movable members for one of said elements, in combination, a rotary drive shaft, mechanism connected with certain of the movable members of the operating means and actuated by said shaft for imparting "a reciprocating movement to the element actuatedby said operating means in a predetermineddirection with respect to the other element, se arate mechanism connected with the other said movable members and actuated by the driveshaft for imparting a reciprocating movement to said element actuated by the operating means in a direction substantially normal to the first mentioned direction of movement thereof with respect to the-other element, each of said mechanisms including a break-up means actuated thereby for automatically varyingthe normal path of movement of the element actuated by the operating means in each of said reciprocating directions during each revolution of the drive shaft.

' 7. A device as in claim 6 wherein one of said drive mechanisms includes means adjustable at will for varying the amount of movement of said members of the operating means and of said element carried thereby.

.8. In a lens grinding and polishing machine having a lens grinding element, a lens holding element and'a movable driving means for one of said elements, in combination, means for operating the driving means including a drive member mounted to rotate about a fixed axis, a crank member connected with the drive member in eccentric relation therewith to revolve about said iixed axis, an'eccentric member rotatably mounted. on the crank member, means rotatably connected to the/eccentric memberfor actuating the driving means to and no for producing reciprocation 01 said elenient' actuated thereby in a predetermined direction with respect to the other element, Wei-Gilliam bythe. revolving motion of the crank member forrotating the eccentric member relative 'tosaid crank member for varying 4 said path of reciprocating'movement of said element including aarain ot gears mounted on the crank member to revolve therewith about said fixed axis, each gear of said train being adapted to rotate relative'tos'aid crank member, and means connected one; of the gears of said train for holding the'same stationary with respect toits axis 01' rotation. I

9. A device as 'in claim 8 having means for adjusting the crank member toward and from said fixed axis to alter the path of travel thereof about said fixed axis.

10. In a machine for grinding lenses or the like having a grinding element and a work supporting element, means connected with one of said elements for producing movement thereof relative to the other element comprising an eccentric member having an axis of rotation, operating means rotatably supporting the eccentric member adapted to revolve said member about a second axis arranged in spaced substantially parallel relation with said axis of rotation, means for rotating the eccentric member comprising a drive ele-- ment having an axis of rotation, means rotatably supporting. said drive element in coaxial relation with the eccentric member and adapted to revolve said drive element about said second axis in unison with the eccentric member, holding means connccted with the drive element having movement therewith during the revolution thereof about said second axis and adapted to maintain said element against rotation about the axis of rotation, and separate rotatable means movable in unison with the operating means about said second axis and actuated by the drive element for producing rotation of said eccentric member about said axis of rotation thereof.

11. A machine of the class described in claim 10, wherein the operating means includes relatively movable members adjustable with respect to each other for producing relative movement of the axis of rotation of the eccentric member and said second axis toward and from each other, and means for releasablysecuring said members in the adjusted position.

12. In a lens grinding machine having a grinding element and a work holding element mounted in cooperative relation with each other and wherein an actuating arm connected with at least one of said elements is operated by means comprising a pair of reciprocative members and drive elements operatively connected with said reciprocative members and mounted to revolve about fixed axes for producing relative movement of the work carried by the holding element and said grinding element in grinding engagement with each other by the combined action of two reciprocative movements operating in directions substantially normal to each other, in combination, separate oper-- ating means including a. .pair of eccentric sleeves and drive members therefor actuated by the revolving motions of the drive elements, said sleeves and drive members being so constructed and arranged that two reciprocative break-up motions are produced by two circular motions and said break-up motions combine with said reciprocative ELT MAYNARD LONG.

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