US2112836A - Lens grinding machine - Google Patents

Description

April 5, 1938. c. E. EVANS 2,112,836

LENS GRINDING MACHINE Original Filed Sept. 8, 1932 7 Sheets-Sheet l @5.5 *167/75 @a jm/v April 5, 1938. C, E, EVANS 2,112,836

LENS GRINDINC- MACHINE Original Filed Sept. 8, 1952 '7 Sheets-Sheet 2 April `5, 1938. c. E. EVANS LENS GRINDING MACHINE Original Filed Sept. 8, 1952 '7 Sheets-Sheet 3 man w@ m WE M E A A. Slm AB April 5, 1938. C, E EVANS 2,112,836

LENS GRINDING MACHINE Original Filed Sept. 8, 1932 '7 Sheets-Sheet 4 IN V EN TOR.

April 5, 1938. E. EVANS 2,112,836A

LENS GRINDINC- MACHINE Original Filed Sept. 8, 1932 '7 Sheets-Sheet 5 l TF INVENTOR. f

BY n Ill- 5 ATTORNEYS.

April'5,193s. C E. EVANS 2,112,836 f LENS GRINDING MACHINE v I original Filed sept. s, 1952 7 sheets-sheet s INVEN 0R. CFZesE' @725.

.M e z5 ATTORNEYS.

April 5, 1938. c. E. EVANS 2,112,836

LENS GRINDING MACHINE original Filedl sept. s, 1932 7 sheets-sheet 7 [NVE/WUR.

Patented Apr. v, 1938 UNITED STATES PATENT OFFICE Applicationseptember s, 1932. serial No. 632,102 Renewed June 19, 1937 This invention relates to grinding machines for spectacle lenses and the like, and its main object resides in the provision of certain novel features and arrangement of parts of a machine of this type which is especially adapted' for grinding a surface of a multi-focal lens with a gradually varying focus which results in producing a surface of gradually Varying dioptric power. It is also an object of this invention to construct a machine of the above character wherein the graduated focal grinding' may be applied to an entire surface of a lens so that the dioptrlc power of said surface varies gradually from one edge to the other, or the novel grinding may be applied to a portion of the lens surface so that either or both edges of the graduated focal area may merge or blend with areas of constant dioptric power. A further object of this invention is to provide a lens grinding machine which may ybe arranged to grind a surface of gradually varying dioptric power on either the concave or the convex side of the lens, or on both sides thereof so as to produce a lens of desired specifications.

vThe invention consists in certain features and elements of construction, in combination, as hereclaims.

E in shown and described, and as indicated by the In the drawings:

Figure 1 is an end elevation of an elementary form of lens grinding machine embodying the present invention; the machine being arranged for producing a graduated` focal grinding on the concave surface of the lens.

Figure 2 is a plan view of the machine shown in Figure 1 with certain parts shown in section, and taken substantially at. the lines, 2 2, on Figure 1.

Figure 3 is a plan view of a slightly modified form of my lens grinding machine which is constructed and arranged to produce a graduated focal grinding on the external or co'nvex side of the lens.

Figure 4 is a view of a lens produced by a machine embodying the present invention, showing diagrammatically the method of generating the gradually varying focal surface.

Figure 5 is also a more or less diagrammatic view of a lens formed by a machine embodying slight modifications of my invention.

Figure 6 is a plan view of a machine embodying a further modification of my invention.

Figure '7 is a View partly in elevation and partly in section taken substantially at line, 1 1, on Figure 6.

Figure 8 is a transverse section through the universal joint connection taken at line, 8 8, on Figure 6.

.Figure 9 is a vertical section through the machinetaken substantially as indicated at line, 9 9 on Figure 6. 5

Figure 10 is a more or less diagrammatic view of the complete machine and driving arrange? ment.

Figure 11 is a vertical section through the speed reducing connection taken at line, H II, on Figure l0.

Figure l2 is a front elevation of a machine embodying a still further modification of the present invention.

Figure 13 is a vertical section taken substantially as indicated at line, l3-l3, on Figure 12.

Figure 14 is a plan view of the machine with the counterweight removed.

The type of multi-focal lens produced by a machine embodying the present invention is fully illustrated and described in my co-pending application No. 579,451 iledvDecember 7, 1931 in which application there is shown several applications of the graduated focal grinding on the surfaces of spectacle lenses. 25

The present invention in its broadest aspect is capable of embodiment in many forms such as, for example, for producing a multi-focal lens with graduated focal surface on either the concave or convex surfaces of the lens or on both surfaces 30 of the lens, or for providing such a grinding on only a portion of one surface of the lens wherein either or both edges of said graduated focal area blend or merge with an area f constant dioptric power. There are many advantages in such a multi-focal lens as compared with the present forms of bi-focals nowin use, as particularly pointed out in my above mentioned copending application.

Referring now to one specific form of my invention illustrated in Figures l and 2 of the drawings: 'I-'he machine for purpose of illustration is shown supported in a horizontal arrangement although it will be manifest that it could be mounted on a vertical support if desired. In this construction the machine includes a pair of spaced apart standards or supports indicated at 5, having'integrally formed bearings, 6, in which is journaled a rotatable shaft, l, and it is to be understood that this shaft is operably connected in any suitable manner to a source of power. Rigidly secured on the shaft, l, intermediate the bearings, 6, by means of a key indicated at 8, is a grinding hob or lap indicated at i0, which in axial section, in general, appears to bean.

ellipse truncated at both ends. The external surface of the grinding hob is shaped so that its contour in axial direction is exactly the contour of the finished concave surface of the lens indicated at I2, when taken on a vertical section through the lens. Rotatably mounted on concentric extensions of the bearings, 6, adjacent the ends of the hob, I0, are a pair of pivot blocks, I3, which are connected by pins, I4, to a pair of yokes, I5a and I 6, secured to the ends vof radius arms, I5 and I6, respectively. These radius arms are of different lengths and preferably correspond to thejfocal radii at the upper and lower edges respectively of an imaginary graduated focal lens that extends from the axis of one pivot, I4, to the other, and from which the desired graduated portion could be cut. When the radius arms are the same length as the nal' radii of-the desired graduated focal area, the graduated focal area will gradually vary in dioptric power from one edge of said area to the other, and the curvature of said area, as indicated by a vertical section through the lens will be approximately an involute curve, while the curvature of the lens in transverse section is entirely controlled by the length of the radius arms.

The pivots, I4, connecting the yokes, I5i and I6, to the blocks, I3, are preferably located so that their axes are intersected by a continuation of the final radii of the grinding hob or lap block as indicated diagrammatically in Figure 2. Such an arrangement of the pivots for the radius arms results in a more accurate formation of the lens surface to the predetermined curvature.

The opposite ends of the radius arms, I5 and I6, are provided withl ball-and-socket connections indicated (more or less diagrammatically) at I1 and I8, respectively, associated .with the laterally extending arm, 20, of the supporting bracket, 20. This bracket is of U-shape formation, as may be seen in Figure 1 of the drawings, and the portion opposite the ball-and-socket connections is rigidly secured by means of screws, 22, to a hand lever, 23, the end of which is also provided with a ball-and-socket connection, 24, to one of`v the bearings, 6.

My improved multi-focal grinding may be formed on the lens surface when the lens is merely a rough blank ord after one or both of its surfaces have been ground to certain specifications. The lens or blank, I2, may be secured in any desired manner such as by pitch, cement, etc., to the blocking body or lens carrier, 25, which in turn is secured to the bracket, 20, by the screws, 22.

" To insure proper adjustment of the lens surface with respectkto the grinding hob or lap, I0, so as vto insure obtaining a predetermined depth of cut, the blocking body and the supporting bracket are arranged to accommodate a series shims, 26, therebetween.

It is to be understood that the grinding hob or lap, II) may be formed of any suitable abrasive material such as carborundum, but preferably of a material that will stand a fair amount of wear without becoming deformed and losing its true shape. The grinding hob may be formed of cast iron or possibly of hardened metal, such as steel, and whenA it is desired to grind the surface of a lens the surface of the grinding hob is supplied with an abrasive or grinding compound such as emery, carborundum, etc. In the event eventhat the grinding hob is formed of hard metal it is possible after being inuse fora substantialperiod of time that its surface may be slightly fworn so asto reduce it in size, and to ltion thereof.

Vof the focus of the lens.

accommodate this wear it may be desirable to provide for adjustment of the pivots, I4, so that their axes may be positioned to intersect the continuation of the arc formed by radii at the outer edges of the lens area being ground, which corresponds approximately to the final radii of the grinding hob, I0.

In operation it will be understood that the hand lever, 23, is oscillated up and down about its universal connection, 24, and it will be manifest that the curvature of the lens in transverse direction will be controlled by the-radius arms, I5 and I6. The radius of curvature transversely of the lens will gradually vary from the radius at the top which is determined by the length of the radius arm, I5, to the radius at the bottom of the lens which is determined by the length of the radius arm, I6. The radii of curvature in the other direction, i. e., parallel to the axis of the hob, is controlled by the contour of the hob, which may be substantially an involute curve, or modifica- It is desirable that the universal connection, `24, be slightly` loose so as to afford a very slight amount of longitudinal movement of the lever, 23, to permit occasional shifting longitudinally, preferably not more than one-thirtysecond of an inch, so as to release and shake free any pieces of emery or other grinding compound that may tend to become embedded in the grinding hob or in the lens surface and thereby prevent cutting of grooves in the lens surface.

The pivot axes of the universal connections, I1 and I8, of the radius arms, I5 and I6, preferably are located on the optical center of the lens so as to obtain the best results. However, if the axes of these universal connections are off of the optical center a slight amount reasonably good results may still be obtained. If desired, the grinding hob could be made slightly longer than the width of the lens blank, and disks or washers in- .terposed between the' blocks, I3, and the ends of the hob so as to prevent emery or other grinding material from coming in contact with the pivots, I4, or the bearings, 6, in which the shaft, 1, is supported.

Because the lens, I2, is shifted back and forth over the surface of the grinding hob about the axis of the universal connection, 24, it will be manifestk that the surface of the lens as it is being ground will not extend truly horizontal with respect to the vertical axis of the lens, but will be slightly curved as indicated diagrammatically in Figure 4. In this diagrammaticrepresentation of the lens surface I have divided the surface up into a plurality of small segments, indicated at I2a, and for purpose'of illustrating theresult to be accomplished it may be assumed that each of these segments is infinitely small, then it will be apparent that the segments adjacent each other vary so slightly in their focal length or dioptric power that one segment almost approximates the other, thus resulting in a Very gradual variation Such a lens relieves the eye of excessive strain which normally results in using multi-focale which cause the eye to accommodate itself to areas of different dioptric cated Aat I2", would extend horizontally, as illustrated diagrammaticaly in Figure 5.l I have devised a modified machine for imparting vertical movement to the lens for accomplishing this result, as will hereinafter be described.

It will be understood that a separate grinding hob or lap block will be required for producing graduated focal grindings of different dioptric powers. However, the number of such lap blocks for accommodating substantially the entire range of requirements should not be very great, particularly in cases where the lap block is to be used merely for forming a graduated focal surface on only a portion of a surface of the lens Where it merges or blends with an area of constant dioptric power. It will be manifest that in order to have the machineaccommodate the grinding hobs or lap blocks for grinding surfaces of a different range of dioptric power, it will be necessary 'that the radius arms, I and I3, be dimensioned accordingly, and it may therefore be understood that these radius arms may be made adjustable so as to vary their eective lengths, to correspond with the radii of the dierent grinding hobs. This adjustment should preferably be made in a manner so' that the axes of the universall connections, and |8will be shftedalong the optical center of the lens.

The grinding hobs or laps could be so formed as to be used in grinding hobs or laps of the reverse design, as for example, the grinding element for producing the hob or lap indicated at .|0, would be formed with a surface substantiallythe reverse of the final surface desired for the hob.

In Figure 3 of the drawings, I have shown a modified machine for grinding the convex or cuter surface of a lens, indicated at 30. 'I'he machine in general is similar to that shown and described in Figures 1 and 2. In this machine the grinding hob or lap indicated at 3| has its outer contour formed exactly to the contour desired on the finished outer or convex surface of the lens. The machine has been slightly rearranged and it will be noticed that the operating lever, 32, is reversed so that the handle portion extends from the same side as the universal pivot, 24, in a direction opposite that shown in Figure 2. It will also be noted that the lens carrier supporting bracket, 33, is disposed entirely at one side of the hob, 3|, with the end of the lever, 32, interposed between a laterally extending leg, 33a, of the bracket and the lens carrier, 25. The pivot blocks, 34, have been reversed with respect to the arrangements shown in Figure 2, and the radius arms have also been shifted so that their pivots, I4, intersect the continuation of the arc formed by the final radii of the Hob, 3|. By virtue of the universal connection, 24, of the lever, 32, as shown in Figure 3, it will be manifest that the graduated surface generated by the grinding hob, 3|, will also be slightly curved with respect to horizontal, as illustrated diagrammatically in Figure 4 of the drawings.

A further modification of my invention is illustrated in Figures 6 to 11 of the drawings, and in which the machine is constructed and arranged to produce a lens surface of gradually varying dioptric power and wherein the transverse radius of curvature of the lens may at any horizontal plane be substantially the same, at any point, as the vertical radius of the lens at that same plane. A lens of the type referred to is shown diagrammatically in Figure 5 of the drawings. This machine is arranged for mounting on a horizontal support and includes a pair of spaced apart standards, 35, each including journal bearings, 36

vu'res 1 and 2 of the drawings.

and 31, disposed in vertically spaced apart relation. Journaled for rotation in the pair of bearings, 36, is a horizontally extending shaft, 3.8, on which is rigidly mounted intermediate said bearings, 36,- a grinding hob or lap, 39, which is similar in formation to the hob or lap shown in the construction embodied in Figures 1 and 2 of the drawings. Journaled on concentric extensions indicated at 36B, of said bearings, 36, adjacent the hob are pivot blocks, 40, to which are connected by pivot pins, 4|, yoke members, 42a and 43a, of the respective radius arms, 42 and.43. 'I'hese radius arms each include a bolt member, 42b and 43h, on which is disposed tubular spacers, 42c and 43, abutting at one end against the yoke members, 42H and 43a, and at the other ends against yoke bearings, 42d and 43d; said yoke bearings, 42d and 43d, are respectively connected by a pair of diametrically opposite pivot studs, 44, to the outer race or ring members, 45, of a pair of universal joints spaced axially along the spindle or member, 41, which is rigidly connected to'l and carried by the supporting bracket, 48, of the lens carrier.

Each of the annular rings, 45, of the universal connections are pivotally connected by means of pivot studs, 49, arranged in diametrically opposite relation to each other and at 90 degrees with respect to the pivots, 44, to an internal annular member, 50, which is loosely journaled on. the member, 41, intermediate a pair of spaced apart stop shoulders,v 41a. Thus the pivotal movement provided between the yoke members, 42d and 43d, and their respective annular elements, 45 and 50, together with the rotary movement permitted by the element, 5U, on the member, 41, provides a universal connection for accommoldating motion imparted to the radius arms, 42

and 43, respectively. The spindle member, 41, is constructed similarly to the radius arms and includes a bolt member, 41h, on which are mounted a plurality of tubular spacers, 41e, interposed between the yokes, 42d and 43d, and the connections to the supporting bracket, 48.

'I'he supporting bracket, 48, in general is similar to the U-shaped bracket, 2U, shown in Fig- The end ofsaid bracket remote from its connection to the member, 41, is up-turned and formed into' a pair of diverging arms indicated at 48a, as may be seen in Figure 7 of the drawings, and to which arms the mounting plate, 52, is connected by means of the thumb screws, 53. Secured to the mounting platev is a spider like element, 54, which includes a centrally located annular support, 55, to which a lens, 56, is rigidly secured by any suitable blocking material such as pitch, indicated at 51. The spider element, 54, may be shifted with respect to the mounting member, 52, by means of the four supporting screws, 58, which are provided for 'the purpose of adjusting the lens to a desired position relatively to the grinding hob, 39. Shims, 532, are provided for controlling the depth of cut to be made on the lens surface. An adjusting screw, 60, is also provided in the member, 52, substantially centrally located with respect to the adjusting screws, 58, and said adjusting screw, 60, is positioned to engage the spider, 54, as seen in Figure 9, and lock it inits position of adjustment. `Secured to the mounting member, 52, is a vertically disposed guide bar, 64,.which is formed with laterally offset leg portions, 34a, and 64b, at top and bottom` respectively. The upper leg, 64a, is conned for engagement in a bifurcatedl or forked guide element, 66, rigidly secured on a shaft,.58, which is slidably mounted in the bearings, 31, of the supports, 35. The lower leg, 64b, is slidably guided in a forked or bifurcated guide, 69, secured to the supporting member upon which the standards, 35, are mounted. Thus the guides, 66 and 69 conne the path of vertical movement of the lens carrier and the lens, 56, as it is moved across the grinding face of the hob, 39.

The shaft, 38, extends at both ends beyond the bearings, 36, and at one end is provided with a pair of pulleys, 10, 1|, which are rigidly secured to said shaft; the larger pulley, 1 I, having a belt, 1|, trained therearound and operably connected to a power source, (not shown). The smaller pulley, 10, is operatively connected by a belt, 10a, for driving the .pulley indicated at 13, of a speed reduction unit indicated generally at 14, and which will be hereinafter referred to. The shaft, 68, which is slidably mounted in the bearings, 31, of the supporting bracket, 35, projects at both ends beyond said bearings and at one end is provided with a xed collar, 16, and a coily spring, 11, circumscribes said extended end of the shaft and reacts between the collarand the adjacent end o-f the bearing, 31. The other end of said shaft is flattened and has pivotally connected thereto the forked end of a vertically extending lever, 18, the lower end of which is pivotally connected at 19, to one of the standards, 35. Intermediate the length of the lever is carried a control roller, 80, which is positioned to operatively engage the face of a cam member, 8|, which is rigidly secured [on the end of the adjacent end of the shaft, 38, opposite the pulleys, 10 and,1|. Thus, as the shaft, 38, rotates the cam, 8|, engaging the roller, 80, will continuously oscillate the lever, 18, about its pivot, 19, and such movement of the lever will cause longitudinal shifting of the upper shaft, 68, in its bearings, 31, against the reaction of the spring, 11. Such movement of the shaft by virtue of the rigid connection of the guide element, 66, will cause the guide bar, 64, to be shifted slightly in lateral direction, and cause shifting of the lens with respect to the grinding hob, which movement insures dislodgment of any particles of emery or any othergrinding compound which tend to become embedded and thus avoid possibility of grooving the surface of the lens or the grinding element. Although in the construction as illustrated it may appear that the lens will be oscillated in a lateral direction quite frequently, it is to be understood that as a matter of fact, the cam, 8|, could be loosely mounted on shaft, 38, and be provided with a pulley connected by a belt to another pulley on an extension of the shaft, 85. Thus the cam could be rotated at a speed different from the shaft, 38.

The speed reducing element, 14, includes a pair of spaced apart standards, 84, provided at the upper ends with bearings, 84, in which is journaled a drive shaft, 85, upon which the` pulley, 13, is rigidly secured. Mounted for free rotation on said shaft adjacent the ends of the bearings,

84a, are a pair of idler beveled plnions, 86, both of which are in constant mesh with a driving gear, 81, which is rigidly secured to the end of a vertically extending tubular driving element, 88, which is journaledV in a yoke member, 89, the ends of which are journaled on the reduced extensions of the bearings, 84, as may be seen in Figure 11 'of the drawings. A clutch element, 90, is featheredonthe shaft, 85, intermediate the gears, 86, and a shifter, 9|, is pivotally mounted on a bracket,

92, for shifting said clutch elementticular advantage,

forselectively engaging either of said beveled pinions, 86, for rotating the tubular driving member, 88, in a desired direction. The upper end of said tubular driving member, 88, is provided with a nut, 93, in which is threaded an operating rod, 94, the upper end of which rod is connected to a beam or lever member, 95, fulcrumed at 96, in the supporting bracket, 91, secured to any suitable mounting. Connected to the opposite end of the lever, 95, is a rod, '98, which is connected to the guide bar, 64, of the lens carrier, as seen in Figures 9 and 10. Thus when the shaft, 38, with the grinding hob is rotated power is transmitted from the pulley, 10, by means of the belt, 10a, to the pulley, 13, and thus drives through the gearing, 86 and 81, for causing rotation of the nut, 93, which in turn threads on the rod, 94, for swinging the lever, 95, about its fulcrum, 96, and thereby vertically moving the guide bar of the lens carrier together Ywith the lens carrier and the lens relatively t'o the grinding hob. It may be understood that suitable stop mechanism may be provided and which is actuated when the drive connections has been engaged for a period of time to move the lens, 56, across the grinding face of the hob, for automatically encountering the shifter, 9|, forreversing the gearing, 86, 81, and, to reverse rotation of the nut, 93, and movement of the rod, 94, in opposite direction for feeding the lens in the opposite direction past the grinding surface ofthe hob, 39. To assist in the feeding of the lens in a downward direction I have secured a counterweight, |00, by means of a rod, to the lower end of the guide rod, 64, of the lens carrier, as seen in Figure l0.

The outer end of the spindle or member, 41, carrying the universal joints, is reenforced to sustain its load by a bar, |05, which is pivotally connected to the member, 41, and has its lower end pivotally connected at |06 to a suitable mounting member. Such an arrangement permits movement of the supporting bracket, 48, and the member, 41, and accommodates movement imparted thereto as *the lens is fed across the grinding surface of the hob. The extreme outer end of the member, 41, is provided with an eyelet, |01, in which is engaged a hook element, |08, and which in turn is connected by a cord or other element indicated at |09, to any suitable counterweight or yielding connection which is provided for the purpose of taking up slack in the parts and also for maintaining the lens in yielding engagement with the grinding surface of the hob.

The shape of the grinding hob, 39, is for producing my improved graduated focal surface on the concave side of the lens, but it will be manifest that a reversely formed hob as in Figure 3 may be employed to grind the outer or convex side of the lens. For such a purpose the radius arms, etc., are reversed as indicated in dotted lines at A in Figure 10. y

It will be recognized that the construction shown in Figures 6 to 10 of-the drawings embodies the essential elements of the elementary machine shown in Figures l and 2. As above referred to, this machine is capable of grinding a lens surface with a graduated focus of gradually varying dioptrlc power and whose` radius ina transverse or horizontal.. plane may be the same as the radius in a vertical plane when taken I at said horizontal' plane. The particular construction shown in Figures 6 to 10 has a parin that the construction of advantages are attained. By virtue of the construction embodied in this machine the formation of the contour of a lens surface is entirely controlled by the mechanical movement of the lens with respect to the grinding surface of the lap, or grinding wheel. For purpose of illustration I have shown a machine arranged for grinding the outer or curved surface of a lens, and for which purpose I employ a grinding element which has a at surface which can be easily maintained true. V

The machine includes a grinding element, |20,

herein shown as of disk type, which is rigidly' connected to a gear, |2|, both of vwhich elements are loosely mounted on a vertically disposed shaft, |22, which is provided with an enlargement or head, |22a, seated in a recess of the grinding element, |20. This shaft, |22, is rigidly secured in a rotary member indicated at |23, which is rigidly connected-to the driving pulley or sheave wheel, 24, and which sheave wheel and rotating member -are loosely mounted on a second vertically disposed shaft, |25, which shaft is rigidly secured (in a position not in line with the center of the lens) in a supporting block, |26, of a bracket, |21, which is adjustably mounted on a vertical support. Rigidly secured to the upper end of the shaft, |25, is a gear, |28, meshing with the gear, |2|, on the shaft, |22, which causes rotary motion to be imparted to the grinding disk, |20. The rotary member, 23, is also provided with a counterweight, |23a, which will tend to maintain uniform rotation of the grinding element, |20, and the member, |23, with the driving pulley, |24, about the axis of the shaft, |25. It will be understood that the grinding wheel, |20, may be composed of stone or other suitable abrasive material, or the wheel may be made of.metal, in which case a suitable abrasive compound such as emery or carborundum must be supplied to the grinding face thereof. I

The pulley or sheave wheel, |24, is driven by a belt, |30, connected to any suitable source of power, (not shown). By virtue of this driving arrangement, it will be manifest that the grinding disk, |20, in addition to being rotated about the axis of the shaft, |22, will also be rotated in an orbit about the axis of the shaft, |25. The purpose of this motion is to insure bringing substantially all portions of the grinding surface, |20, into abrasive contact with the surface of the lens to be ground, with a continually changing direction, and such action, of course will tend to maintain the grinding surface of the member,

|20, true, and thus produce true and accurately ground surfaces of the lenses.

Arranged above the grinding unit is a carriage which is composed of two transverselyr spaced side plates, |32, which are secured together in spaced apart relation by a pair of transversely spaced cross members, |33 adjacent the bottom of said side plates and by meansof tie rods, |34, ad-V,

jacent the upper ends of said plates, and on which rods are carried a plurality of tubular spacing elements, |35. Arranged centrally of the side plates, |32, are two vertically disposed radius rods, |31 and |38, each having their lower ends provided with a ball-and-socket connection indicated at |318, |38, with the cross members, |33, as may be seen in Figure 13 of the drawings. These radius rods are of different. lengths and correspond to the radii of curvature of different portions of the surface of the lens, as mentioned with,

respect to one of the other constructions. It will be understood that these radius arms may be made adjustable in any suitable manner so as to vary their length for forming the surface of alens whose radii of curvature are larger or smaller and the dioptric power of which will cover a certain predetermined range. The upper ends of these radius arms are each provided with a yoke member, |31b and |38b, which are connected respectively to universal joints indicated generally at |39, |40, mounted on a vertically extending spindle, |4|. It may be understood that these vuniversal joints, |39 and |40, are substantially the same as the universal joint constructions shown in the construction embodied in Figures 6 to 11 of the drawings.

The upper portion of the spindle, |4|, is provided with a sphere-like element, |4|, which is slidably disposed between a pair of transversely extending guidefbars, |43, which are mounted on the rods, |34, intermediate the spacer elements,

|35, as may be seen in Figure 12 of the drawings.

The extreme upper end of the spindle is provided with a counterweight, |44, which tends to take up any looseness in the joints of the respective elements, as will hereinafter be made clear.

Rigidly secured to the lower end of the spindle, |4|, is a guide block, |46, which is mounted for sliding guidance between a pair of faces formed on the. inner edges of the cross members, 33, as

may be seen in Figure 13 of the drawings. Secured to this guide block by means of screws, |41, is the lens carrier; |48, to which the lens, |49, is secured by means of pitch or other suitable material which is indicated at |50.

Journaled on pins, |52, carried in the side plates, |32, are a, pair of rollers, |53, disposed outside of said plate and which are positioned to engage 'a substantially vertical surface of the guide legs, |54, rigidly secured to mounting brackets, |55, which brackets in turn are secured to'the vertical mounting. Rigidly secured to the outer sides of the side plates, |32, adjacent the rollers, are a pair of gear segments, |51, which mesh with vertically disposed racks, |58, which are rigidly secured to the inner'surface of the two spaced apart arms of the supporting brackets, |55, -as may be seen in the drawings. 'I'he gear segments and the racks normally tend to support the entire carriage with the lens and its control members on the racks of the supporting brackets, |55,` and when it is desired to take a predetermined depth of cut oif the surface of the lens,

|49, the bracket, |21, is'adjusted so as to dispose the surface of the grinding4 member, |20, in

atively connected to a suitable source of power for imparting reciprocatory movement to this rod and which in turn, will cause oscillation l of the entire carriage by rocking the gear segments, ,|51, on the racks, |58, and because the gear segments are of circular outline, it will be manifest that the surface ground on the lens, |49, as it is shifted back and forth over the surface of the grinding member, |20, will be smooth and true to form, and any element of the lens surface which is parallel to the direction of such movement, will be substantially a, true involute curve. It will be seen that during this grinding movement of the lens surface different portions of thesurfaceof the grinding member, |20, are continuously brought into abrasive contact with the surface of the lens.

It may be advantageous to have the gear segments, |51, deviate from a, circular arc in order to modify the involute curve. Segments of various radii may be used to produce a lens of different curvatures.

The lens, |49, is also moved in a direction transverse to the direction of movement caused by the rod, IGI, by a connecting rod, |63, which is pivotally connected at |64, directly to the guide block, |46. By shifting the rod, |63, the path of movement of the lens is controlled by the block, |46, being guided between the surfaces of the con-- necting members, |33. Such movement of the lens over the surface of the grinding member, |20, is entirely under the control of the radius arms, |31 and |38, as in the constructions above described. During such movement it will be seen that the spheroid member, |4I, at the upper end of the spindle will act as a fulcrum between the guide bars, |43, and about which fulcrum the spindle with the lens and connecting parts will swing as a pendulum. Thus the radius of curva.- ture of the lens which is produced by the movement thereof through the connecting rod, |63, will be constant in any one plane from one edge to the other. Due to the difference in length of the radius rods, |31 and |38, the curvature of the surface in this direction varies in different planes, and the length of the radius rods maybe so chosen that the dioptric curvature of the lens surface may be the same in all directions at any given point. It may be understood that the motions imparted to the lens through the connecting rods, |6| and |63, may be performed successfully or conjointly and during either of which motions the grinding member, |20, is continuously rotating about the axis of the shaft, |22, and also about the axis of the shaft, |25.

The purpose of the counterweight, |44, at the upper end of the spindle, l|4|, is particularly desirable in a construction such as that illustrated herein, wherein I employ a gear. segment and rack, because in suchl a construction, the counterweight will always take up the back lash in the gear teeth. It will be-understood that other suitable arrangements may be substituted for the gear segment and rack and which may be equally or more satisfactory, as, for example, the gear segments might be replaced by segments of drums rolling against fiat bars and the drums being connected to the bars by cords or strips of flexible metal extending around the face of the drums and anchored to both the drum and the bar. Such an arrangement would eliminate all back lash.

It will also be evident that the machine may be altered by re-proportioning or rearrangement of the parts so as to produce different grindings on the surfaces of the lenses. 'Ihis particular construction has a special advantage in that the entire carriage and the spindle and lens may be bodily removed from the racks and the supporting brackets, |55, and be re-located over a grinding element of different abrasive character. And

by this arrangement the lens may be progressively ground by what is known as multi-stage grinding.

I am aware that the machines embodying my invention as above described may be so altered as to permit grinding lenses of special curvatures such as so called cylinder lenses or perhaps even spherical lenses, and as may be seen, all of these machines can be so arranged as to serve in forming lap blocks or grinding members for use in grinding the surfaces of the lenses.

Although I have shown and described certain preferred forms of my invention, it is manifest that my invention is capable of further modification and rearrangement of parts without departing from the spirit and scope thereof. I do not, therefore, Wish to be understood as limiting myself to the constructions herein shown and described, except as indicated in the appended claims.

I claim: A

1. In a grinding machine, the combination of a grinding member, a work piece carrier, a support therefor, means for moving the support and carrier for bringing the work piece into operative engagement with the grinding member, and a pair of radius arms connected to the support for controlling the path of movement of the work piece for determining the curvature of a surface area thereof in one direction, said radius arms being of different lengths which correspond to the final radii of curvature that would obtain ifthis area were extended until it intersected the pivot axes of the respective radius arms.

2. In a lens grinding machine, the combination of a grinding member, a lens carrier, a support therefor, means for moving the support and carrier for bringing the lens into operative engagement with the grinding member, and a pair of radius arms connected to the support for controlling the path of movement of the lens, for determining the curvature of a surface area thereof in one direction, said radius arms being of different lengths which correspond to the final radii of curvature'that would obtain if this area were extended asa graduated surface, until it intersected the pivot axes of the respective radius arms.

3. In the construction defined in claim 2, the connections of said radius arms to the support comprising universal mountings located on an axis extending substantially through the optical center of the lens.

4. In theconstruction defined in claim 2, the connections of said radius arms to the support comprising universal mountings located on an axis extending substantially through the optical center of the lens, said mountings for the radius arms being adjustably movable along said axis toward or away from the lens for varying the curvature of the lens surface.

5. In the construction defined in claim 2, said support and carrier being mounted for swinging as a pendulum about an axis substantially perpendicular to the optical center of the lens.

. 6. In a lens grinding machine, the combination yof a rotary grinding member, a lens carrier, a

.the curvature of a surface area thereof in the one direction, the contour of the grinding member in axial direction being such as io produce a gradually varying dioptric curvature of said lens face in the other direction.

7. In the construction defined in claim 6, said support and carrier being constructed and arranged to permit movement of the lens over the surface of the grinding member in a. direction parallel to the axis of said grinding member.

8. In the construction dened in claim 6, said support being mounted for movement in a plane transverse to the axis of said grinding member, and substantially parallel to the horizontal center of the lens.

9. 'In the construction defined in claim 6, means Sul'- for guiding the lens carrier for travel in a path that is substantially perpendicular to the axis of the grinding member.

10. In a lens grinding machine, the combinal tion of a grinding member, a lens carrier, a support therefor,V means for oscillating the support and carrier for bringing the lens into operative engagement with the grinding member, and a pair of radius arms of different predetermined lengths connected to and disposed on opposite sides of the support for controlling the path of movement of the lens, for determining the curvature of a surface area thereof in one direction, the radius arms being provided 'with universal connections at each end.

11. In a lens grinding machine, the combination of a grinding member, a lens carrier, a support therefor, means for oscillating the support and carrier for bringing the lens into operative engagement with the grinding member, and a pair of radius arms of different predetermined lengths connected to and disposed on opposite sides of the support for controlling the path of movement of the lens, for determining the curvature of a surface area thereof in one direction, the radius arms being provided with universal connections at each end, theuniversal connections of the radius arms to the support being substantially on the optical center.

12. In a lens grinding machine, the combination of a rotary grinding member, a lens carrier, a movable support for the carrier, means for moving the support and its carrier for bringing rthe lens into operative engagement with the grinding member, the contour of the grinding member in axial direction servingv to determine the dioptric curvature of the lens in one direction, and a pair of 'radius rods for determining Athe dioptric'curvature of the lens in the other direction, said radius arms being universally connected at both ends, each arm having one end connected to the support, and the other end arranged for turning about the axis ofthe grinding member. 13. In a lens grinding machine, the combination of a driven shaft, a grinding member mounted on said shaft, a lens carrier, a movable support therefor, means' for moving the support for bringing the lens into operative engagement with the grinding member, the contour of the grinding member in axial direction being arcuate and serving to determineA the dioptric curvature of the lens in one direction, a pair of pivot blocks journaled on the shaft at opposite ends of the grinding member, and a pair of radius rods for determining the dioptric curvature of the lens in the other direction, said radius rods each being 14. In the-construction defined in claim 13, the

axis of the pivotal connections of the radius arms to th'e pivot blocks being located to substantially intersect a continuation of the arcs of the final radii of curvature of said grinding member.

15. In a lens grinding machine, the combina.- tion of a grinding member, a movablesupport, a lens carrier on the support, means for moving said support and carrier in one direction across the grinding surface, means for controlling the path of travel of said carrier in such movement for determining the dioptric curvature of the lens in one direction, means for moving said carrier into operative engagement with the grinding member transversely of the above mentioned movement, and control means for confining the tion, said first mentioned controlmeans being constructed and arranged for causing the carrier to be so moved that the dioptric curvature of the surface of the lens ground by such movement gradually varies from one edge toward the other.

16. In a lens grinding machine, the combination of agrinding member having a substantially fiat grinding surface, an oscillating support, a, lens carrier on the support, means for moving said support and carrier in one direction across said grinding surface, means for controlling the path of travel of said carrier in such movement for determining the dioptricl curvature of the lens in one direction, means for moving said carrier into operative engagement with the grinding member, transversely of the above mentioned movement, and control means for confining the path of travel of the carrier for determining the dioptric curvature of the lens in the other direction.

17. In the construction defined in claim 16, said first mentioned control means being constructed and arranged for causing the carrier to be so moved that the dioptric curvature of the surface of the lens ground by such movement gradually varies from one edge toward the other.

18. In a lens grinding machine, the combination4 of a grinding member, a movable support, a lens carrier on the support, said support being mounted for swinging as a pendulum, means for swinging the support about its fulcrum, means for moving the support transversely of such swinging movement for bringing the carrier with said lens into operative relation to the grinding surface, and a pair of radius arms of different lengths connected to said support and arranged for controlling its movement in the path of travel of the carrier with the 1ers over the grinding surface for determining the curvature of the lens in one direction.

`19. In a lens grinding machine, the combination of a grinding member having a, substantially at grinding surface, a movable support, Aa lens carri r on the support, said support being mounted fo swinging as a pendulum, means for swinging the support about its fulcrum, means for moving the support transversely of such swinging movement for bringing the carrier with the lens into operative relation to the grinding surface, and a, pair of radius arms of different lengths, connected to said support and arranged for controlling its movement and the path of travel of the carrier with the lens over the grinding the support and with it the lens into operative engagement with the grinding member, means for controlling the path of movement of the support over the grinding member for producing a surface area on the lens the contour of which in one direction is substantially an involute curve gradually varying in dioptric curvature from one edge toward the other, and separate means for controlling the path of transverse movement of the support and lens over the grinding member for producing a desired curvature of said surface area in the other direction.

21. In a lens grinding machine, the combination of a grinding member having a substantially flat grinding surface, an oscillating support, a lens carrier on the support, means for moving the support and with it the lens into operative en gagement with the grinding member, means for controlling the path of movement of the support over the grinding member, for producing. a surface area on the lens the contour of which in one direction is substantially an involute curve, gradually varying in dioptric curvature from one edge toward the other, and separate means for controlling the path of transverse movement of the support and lens over the grinding member for producing a desired curvature of said surface area in the other direction.

22. In a lens grinding machine, the combination oi' a grinding member, a movable support, a lens carrier on the support, means for moving the support and with it the lensinto operativeengagement with the grinding member, means for controlling the path of movement of the support and lens in one direction relatively to the grinding member adapted to shift the effective center of such movement gradually and continuously through a predetermined range, and separate means for controlling the path of transverse movement of the support and lens relatively to said grinding member.

23. In a grinding machine, the combination of a rotary grinding member, a work piece carrying member, one of said members being `movable relatively to the other into operative position, said grinding member being rotatable during grinding operation, means for imparting oscillating movement to one of said members for producing a predetermined curvature on a surface of the work piece in one direction, means for imparting transverse oscillating movement to said last mentioned member for producing a gradually varying curvature in a transverse direction on said surface of the work piece, and means for moving the rotary grinding member bodily in a, predetermined path independent of its axis of rotation.

24. In a grinding machine, the combination of a grinding member, a work piece carrying member, one of said members being movable relatively to the other in operative position, a movable support for the work piece carrying member., means for imparting oscillating movement to the work piece carrying member relatively to the grinding member for producing a predetermined curvature on a surface of the work iece, in one direction, a segment of desired form on said support, and a cooperating fixed track, and means for imparting transverse oscillating movement to the support and carrier, causing rocking of the segment on its track and movement of the work piece relative to the grinding member in a manner to produce a gradually varying curvature in a transversedirection on said surface of the Work piece.

25. In the construction defined in claim 24; said support including means for guiding the work piece carrier as it is oscillated in the support.

26. In the construction defined in claim. 24, a vertically disposed spindle connected at its lower end to the Work piece carrier, means for guiding the carrier as it is oscillated in the support, said spindle being fulcrumed adjacent its upper end in said support, to permit such oscillation of the carrier.

2'7. In a grinding machine, the combination of a grinding member, a movable support, a vertically disposed spindle fulcrumed adjacent its upper end in said support, a work piece carrying member at the lower end of the spindle, means on the support for guiding the carrier member in one direction of oscillating movement relatively to the grinding member, a pair of radius rods of different predetermined lengths, connected at one end to the support and at the other end to the spindle, for controlling the path of movement of the Work piece, for producing a. predetermined curvature in one direction on a surface of said work piece, a segment on the support, a cooperating fixed track, and means for rocking the segment back and forth on its track, thereby oscillating the Work piece, carrier and spindle in transverse direction lrelatively to the grinding member, for producing a gradually varying curvature in a transverse direction on said surface of the Work piece.

28. In a lens grinding machine the combination of a grinding member having a substantially fiat grinding surface and mounted for rotation about an axis normal to said surface, a swingable support, a lens carrier on the support and means for swinging said support and carrier` relatively to said grinding surface for causing the lens to engage said grinding surface in substantially line contact as it is moved thereover.

CHARLES E. EVANS.

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