US2023525A - Lens grinding machine - Google Patents

Description

@fit. HQ, 1%35. L HOUCHIN 2,023,525

LENS GRINDING MACHI-NE Filed March 1, 1955 4 Sheets-Sheet l INVENTOR. Lowel/ L. Houc/mz ATTORNEYS.

Ben M, 1935. L HOUCHW 2,@23,525

LENS GRiNDI'NG MACHINE Filed March 1, 1935 4 Sheets-Sheet 2 IN V EN TOR.

ATTORNEYS? LENS GRINDING MACHINE m. m, m5. L L HOUcHlN 2,023,525

LENS GRINDING MACHINE Filed March 1, 1955 4 Sheets-Sheet 4 INVENTOR. Lowe L. /'/0UC/7lf).

BY M y ATTORNEYS.

Patented Dec. 10, 1935 UNITED STATES PATENT OFFICE LENS GRINDING MACHINE Lowell L. Houchin, Columbus, Ohio Application March 1, 1935, Serial No. 8,903

12 Claims. (01. .51--119) My invention relates to a lens grinding machine. It has to do, more particularly, with a lens grinding machine which is particularly suitable for grinding toric or cylindrical lenses but which is also capable of use in grinding. spherical .lenses.

One of the objects of my invention is to provide a lens grinding machine of the type indicated which is of very simple construction and which will operate in a very eflicient manner.

Another object of my invention is'to provide a lens grinding machine of such a nature that the grinding lines will be effectively broken up so that the lens produced will have a smooth surface and polishing will be reduced to a minimum.

Another object of my invention is to provide a machine of the type indicated wherein all the necessary adjustments may be conveniently and quickly made.

Another object of my invention is to provide a lens grinding machine which is suitable for grinding lenses of any curvature and, particularly, for grinding lenses of strong plus curvature without buckling of the lens relative to the grinding tool.

Another object of my invention is to provide a machine which has a minimum number of moving parts and which is so designed that friction and wear will be reduced to a minimum.

In its preferred form my invention contemplates the provision of a table which carries the lens grinding lap or tool. This table is so mounted that it will have a rotary motion, which may be easily varied, but it will not rotate about its own axis. In other words, the table will move bodily in a rotary path in such a manner that any point on its surface shall describe a circle of the same diameter as that described by any other point on its surface and any straight line drawn on its surface will move into successive positions which are parallel with each other. The lens is carried by a block which is mounted on a rocker arm that is reciprocatedtransversely in a straight line in order to cause the lens to move relative to the lens grinding lap or tool which is carried by the table. Thus, the lens grinding lap or tool is caused to move in a rotary path and the lens is caused to move in a straight line transversely of the lens grinding lap. However, this straight 50 line movement preferably at an angle relative to'the axis of the lap or tool, as will be explained more in detail hereinafter. This combination of movements breaks up the lines so that a smooth surface will be produced on the lens and polish! ing willibeireduced to a minimum The preferred embodiment of my invention is illustrated in the accompanying drawings wherein similar characters of reference designate corresponding parts andxwherein:

Figure '1 is a perspective view of a machine 5 made in accordance with my invention.

Figure 2 isa perspective view of the machine taken from a different angle than that of Figure '1.

Figure 3 is a detail in perspective of the mecha- 10 nism for causing the lens carrier to reciprocate in a straight line transversely of the lap or tool carrier.

Figure 4 is a detail, in section, of the rocker arm which carries the lens carrier. 15

Figure 5 is a side elevation, partly broken away, of the machine.

Figure 6 is a plan view of the machine.

Figure '7 is a vertical section taken through the table or .carrier which carries the'lens grinding lap 20 or tool.

Figure 8 is a horizontal section taken substantially on line 8-8 of Figure 7.

Figure 9 is a View, more or less diagrammatic, illustrating how the straight line motion imparted 25 to the lens blank is at an angle relative to the axis'of the tool or lap.

With reference to the drawings, I have illustrated my machine as comprising a baseplate l upon which is mounted a pan 2. The pan and 30 base I have .a central opening through which a vertical spindle or shaft 3 passes. This'shaft or spindle 3 is suitably mounted for rotation, preferably in anti-friction bearings such as ball bearings. On the shaft '3 directly above the bottom 35 of the pan .2 .is a cap 4 which prevents abrasive from reaching the bearings of shaft 3.

The shaft Sis driven'by a belt drive 5,:as shown in the drawings, froma suitable source of power.

Rotation of shaft -3 is controlled .by'a clutch of 40 a suitable type which is indicated generally by the numeral '6.

The spindle 3 is adapted to carry at its upper enda'table or .carrier upon which the lens grinding tool or lap is adapted to be mounted. As shown best in Figure 7,-the extremeupper end of the spindle 3 is positioned inthehub 1 formed on the lower surface of a disk or plate 8 and is suitably keyed therein. A second plate or disk 9 rests on the upper surface .of the plate or disk 8. This plate or disk 9 is held in position on the disk 8 by .means of .a pair of screw bolts Ill which depend from the plate or disk 9 and which pass through a pair .of slots ll formed in the disk 8.

"The disk .'9.;may ibe adjusted concentrically ;or

.Below the'base l, the shaft 3 hasapulley 23 eccentri'cally relative to the disk 8 and will be held in properly adjusted position if the bolts ID are properly tightened. V

The disk 9 carries the table or tool carrier l2. The table or tool carrier I2. is preferably of circular outline and has a depending stub shaft 3a disposed centrally thereof. This stub shaft 3a projects into a hub l3 formed eccentrically of the disk 9. A chamber is provided in the'lower surface of thedisk B and a ball bearing 14 is disposed therein in surrounding relation to the lower end of stub shaft 3a. A second ball bearing I5- is provided between the hub 13 and a depending shoulder l6 which extends from thelower surface of the table [2. These roller bearings serve to prevent tilting of the table I 2 and to reduce friction to a minimum during rotary movement of the table I 2. The table I2 has a depending skirt l1 adjacent its periphery which extends down in overlapping relation to the 9. This prevents abrasive from reaching the bearing l5.

It will be apparent that when the shaft. 3 is rotated, the disk 8 and the disk 9 will also rotate therewith. Since the table I2 is mounted eccentricallyon the disk 9, it will be moved bodily in a rotary path. When the disk 8 and disk 9 are in coincidence, as indicated inFigure 7, the table will move through its maximum rotary path. During this maximum rotary movement of the table, the weight of disks 8 and 9 will be equally distributed around the shaft 3. Thus, since there. will be no unbalanced centrifugal force with relation to disks 8 and 9, vibration will be reduced to a minimum. The extent of the rotary movement of the table may be varied by adjusting disk 9 relative to disk 8 so that shaft 3a will move closer to shaft 3. 'However, 7 I provide means to be subsequently described in detail for preventing the table I 2 from rotating about its own axis. Because the shaft 3a is rotatably mounted in the member 9, rotation of member 9 and member 8 about the axis of shaft 3 is permitted, even though rotation of table I2 about L will have any desired curvature or' curvatures thereon depending upon the curvature or curvatures to be produced on the lens. Opposite the shoulder I8 is an upstanding lug I9 which is formed on the table. This lug I!) has a screw threadedtherethrough. A'wedge member 2| of the'shape shown is pivoted to.lug l9, as at. 22.

When the screw 20 is threaded inwardly a sufficient distance its end contacts with the pivoted wedge member 2| and forces it downwardly between the lug l9 and the edge of the lap L.

. This forces the. lap L. firmly into contact with the shoulder I8. Thus, the lap may be readily mounted on the table l2. and will be tightly held inposition thereon. To remove the lap from the table, it is merely necessary to loosen the screw 129:. The'lap L is mounted on the table I2 in such 7 a manner that its longitudinal center line would be intersected by the axis of stub shaft 3a if it were continued.

(Figure'5) keyed thereon. Through the medium .of a belt 24 this pulley 23 drives a pulley 25 which is keyed on'the lower endof a shaft 26. This closely adjacent Walls 31.

the wear of the roller bearings 39.

shaft 26 is mounted in an upstanding vertically disposed housing 21. The shaft 26 is preferably mounted in ball bearings adjacent its upper and lower ends. The housing 21 is bolted or otherwise secured to the rear surface of an upstand- 5 ing vertical support 28 which is secured to the base plate I adjacent its rear edge.

The vertically disposed support 28 has a yoke formed at its upper end. A housing 23 is positioned'on the upper end of each arm of this yoke (Figure 3). Each housing, 29 has a pair of spaced rollers 33 disposed therein. Each'of these rollers has a continuous groove formed in its periphery. A shaft 3| has one end passing between one of the pair of rollers 33 and its oppo- 15 site end passing between the other pair of rollers. The grooves in the rollers cooperate with the cylindrical surface of the shaft 3| to maintain it in position. However, the rollers are so arranged relative to the shaft 31 as to permit longitudinal 20 reciprocation of the shaft.

The shaft 3| has a rocker arm 32 mounted thereon. This shaft 3| passes through a hub 33 formed intermediate of the front and rear ends of the rockerarm; The shaft is keyed in the hub 25 so that it will not rotate therein and so that the rocker arm may not slide along the shaft 3!. However, the shaft is disposed between the rollers .30 in such a manner that it may rotate around its own axis in order to permit tilting of the rocker arm 32 about the axis of this shaft.

The rocker arm 32is made in two sections as shown in Figures 4 and 5. One of these sections 34 is the section which has the hub 33 formed thereon. The other section 35 is connected 35 thereto in the manner illustrated in Figure 4. Thus, the forward end of the section 34 is provided withia pair of spaced depending lugs. 36. The rear end of the section 35 is provided with a socket formed by side walls and transverse walls 37. This socket receives lugs 35 which will be 7 Each lug'36 has a stub shaft 38 passed therethrough and the outer end of the stub shaft is disposed in a roller bearing 39 mounted in the, wall 3'! of section 35. Thus, the section 35 may rock relative to the section 34 and friction will be reduced toa minimum by the ball bearings 39.

I provide means for automatically taking up This means comprises an expansion spring 48 which has its rear end abutting the inner surface of the rear 2 lug 36 and its forward end disposed in a socket member 4| formed on the rear end of stub shaft 38. This stub shaft 38 is normally held immovable in position by set screw 42a but when said .screw is loosened it is free to slide in the opening in the forward lug 36. The other stub shaft 38 is held in position by a set screw 42. When the set screw 42a is loosened, the spring 40 will tend to move the forward stub shaft 38 in the direction of the arrow (Figure l) which will also tend to move'the section 35 of the rocker arm in the direction of the arrow. This will take up or compensate for wear of the forward roller bearing 39 and, since the rear stub shaft 38 is held in position by screw 42, will also-take up or compensate for Wear in the rear roller bearing 39.

The forward end of the section 35 of the rocker arm is inclined upwardly and outwardly as at 43 and then is continued horizontally outwardly as at 44 (Figures 1, 2 and 5). Thus, the forward portion 44 of the rocker arm is at a much higher level than the rear portion thereof. The forward end of the section 35 of the rocker. arm car.- 7 5 adjusted position by a screw 54.

hes a block which .is adjustable thereon by meansof a bolt 45a. This block 45.has.a pair of depending pins '45. These pinslfitintoa pair of sockets formed in the upper surface of 'a lens blank holder H in such a manner that they may rock therein. The .lens blank holderH may be of anysuitable type and has a lensblankcemented to its lower surface. The extreme forward end of the section 35 of the rocker .arm has a handle 47 formed thereon bymeans of which the rocker arm may be swung between inoperative and operative positions, as will be subsequently described.

The lens blank holder is carried by the rocker arm in such a manner that the lens blank will contact with the upper surface .of the lap or tool L. The means for maintaining contact between the lens blank and lap with sumcient force to produce eifective grinding comprises a thrust rod 48 which has its lower cone-shaped end (Figure l) disposed in a socket is, which is formed in the upper surface of section 35 of the rocker arm, in such a manner that it may rock therein. This, rod :48 passes loosely upwardly through a sleeve 5.0 (Figures 1, 2 and 5) formed on the outer .end of an arm 5|. The arm 5! has a sleeve 52 at its rear end which fits over an upwardly projecting pin 53 that is supported on a member 28a which is mounted on the supporting structure 28. The arm 5! may be adjusted to any vertical or lateral position relative to pin 53 and may be held in Therod 48has a head 55 on its upper .end'which will prevent it from passing downwardly through the sleeve 55. The rod is caused to exert adownward pressure on the rocker arm by'means of expansionspring 55. This expansion spring 55 has its upper end abutting the lower end of sleeve 55 and its lower end abutting a collar 51.

It will'be'apparent that the spring 55 will press down and cause the rocker 'arm to forcethe lens blank into resilient but firm contact'with the lens grinding lap. This pressure 'whichmaintains the lens blank and lap in contact may be varied readily'by adjusting the arm 251 vertically on pin 53. The lower end of the rod as contacts with the section 35 of the rocker arm at the lowest point of the rocker arm. Thus, it will 'be apparent from Figure 1 that the force exerted by spring 55 is applied to the, rocker arm1at a point which is below the upper surface of the lens grinding lap. It is importantto apply the pressure, which maintains the .lap and lens blank in -contact,.at this low point on the rocker arm because this prevents buckling or the lens Zblank on the lap, especially 'whengrinding strong'plus lenses. Since the outer end of the .rocker arm is higher than its rear portion, there is a downward pull exerted on the outeriportion 'of the'arm tending to keep the lens blank andlap incontact, rather than a downward thrust. It is also important to have the spring 55iandrod i8 located at a point spaced rearwardly from the forward end of the rocker arm so as not 'to' interfere with the operator when positioning the lens blank carrier or lap on the machine and withinspection during the grinding operation.

As previously stated, I provide means for causing the lens blank carrier to be reciprocated trans- Versely in a straight line relative to the lap L which is mounted on the table i2. ..This means comprises a diski58 (Figure 3) which is keyed on the upper end of a shaft 26 that is rotatably supported in the housing 21. Thisdisk 58 has an undercut groove 59 in its upper surface. This .orrock on the rear section 54. lens blank Will..always contact firmly with the on the table.

undercut groove 59receives the head ofa threaded bolt fiil which is held .in adjusted position along the groove 59 'by means of a nut 5i threaded thereon. This bolt has an antifriction roller 62 mounted thereon. This roller 62 is disposed between the legs .of the bifurcated rear end 53 of the rocker arm 32. The bolt 55 which carries the roller 52 may be adjusted along the groove 59 until it is eccentrically disposed relative to the disk58. It may be held in any adjusted position. When it is eccentrically disposed and the shaft 25 and disk 58 are rotated, the rocker arm 32 will be .moved laterally back and forth since longitudinal reciprocation of shaft Si is permitted. This will cause the lens blank carrier to reciprocats in a straight line transversely of the lap L. During this lateral reciprocation of the rocker arm 32 the forward section 35 thereof may tilt Consequently, the

lap L. The extent of the lateral reciprocation of therocker arm 32 maybe varied by varying the eccentric position of the bolt 56 and roller 52 relative to the disk 58.

In addition to the reciprocating motion imparted to the lens blank carrier, a rotary motion is imparted to the lap L by the mechanism shown in'Figure and previously described. However, as previouslydescribed, means is provided for preventing the table l2 and, consequently, the lens grinding lap, from rotating about its own axis. In other words, the table will move bodily in a rotary path in such a manner that any point on its surface will describe a circle of the same diameter as that described by any other point 00 onitssurface and any straight line drawn on its surface'will move into successive positions which are parallel with each other. Thus, although the lens blank carrier reciprocates in a straight line and the lap Lmoves in'a rotary path, the lens blank and lap will not rotate relative to each other and, consequently, the proper curve or curves will be imparted to the lens blank'by the lap.

The meansfor preventing rotation of the table 12 about its axis and, consequently, rotation of the lens blank relative to the lap, will now be described. This means includes a pair of diamertically opposedlugs or projections 54 (Figures 2 and 6) whichare formed integrally on the table '52. These lugs are in line with the longitudinal center line oriaxis of the lap L which is mounted The rear edge of each lug has a cup formed therein which receives a point formed on the forward end of a thrust rod55. The rear 'end of this thrust rod also has a point formed thereon which fits into a cup bearing formed on the lower'end of a substantiallysemicircular arm '65. The upper end of the arm 55 has a split collar 6'5 which fits around one end of a shaft 55 that has its opposite ends rotatably mounted in bearings 69 which are supported on the housings 29 at oppositesides of the-machine. t will be apparent that one of these members 65 is secured to each endiofshafttfi. The pointed ends of each rod'are held inthe cups by means of a tension spring 75.

One .end of the tension spring is hooked over a hook H connected to the lug The opposite end is connected by a hook "E2 to the lower end of the arm 56. In theinitial adjustment of the --machine the bolts Elarnay be loosened to permit adjustment of the arms-5.50m the shafttt.

The rods 55 and arms '55 will permitthe table "2 to move bodily in a rotary path but will prevent it from rotating about its own axis. Thus, the

.lap will *beprevented from rotating relative to the lens blank. Consequently, the curves on the-lap will be imparted to the lens blank. The rods 65 are stifi enough to keep from bending during operation of the machine. Each end of each rod is free to rock in the cup bearing. Consequently, the rotary motion of the table will be permitted without bending the rods 65 and with a minimum' amount of friction being generated. Because the rods 65 do not bend during rotary movement of the table, the lens blank will always be accurate-' ly held in its proper position relative to' the lens grinding lap.

As shown in Figures 6 and 9, one of the rods 65 is slightly longer than the other. Thus the diameter line A-A which passes through the center of lugs .64 is at an angle to the shaft 3|. In positioning the lap L and the lens blank B on the machine, the axis of the blank and the axis of the lap are brought into coincidence and these axes will lie along the line -AA. However, the direction of the'straight'line recipro cation of the lens blank will be in the direction of the straight line D-D' which is at an angle to the axis of the lens blank and lap and at an angle to the line A-A; Thus, although rods 65 will function to maintain the axis of the lens blank parallel to the axis of the lap at all times during the rotary movement of the table, the straight line motion of the blank will be at an angle to the axis of the lap.

I have found that it is important to have this straight line reciprocation of the blank at an angle relative to the axis of the lap. During the grinding of the lens blank, the blank moves into overlapping relation with the edge of the lap. If the straight line reciprocation is parallel.

to the axis of the lap, I have found that waves may be produced in the lens blank but if the straight line reciprocation is at an angle to the axis of the lap, the production of these waves.

,ever, rocking of this member 28a is normally prevented by a latch member 13 (Figures 1 and 2). This latch member 13 is of arcuate form and is pivotally mounted on the member 280..

It has a depending lug 14 which normally is.

dropped down in front of a plate 15 which is rigidly carried by the supporting structure 28. The spring 56 exerting pressure against the rocker arm will tend to cause the arm 5! to swing upwardly and, consequently, the member 28a to rock about its pivots. However, since the lug 14 is in engagement with the forward edge of plate 15, this will be prevented and, consequently, thespring' 56 will force the rocker arm 32 downwardly. V o r However, when it is desired to replace a lens blank or lap, the latch 13 is disengaged from the plate 15. This will permit the member 28a to rock about its pivot points and the arm 5f to swing upwardly. A spring 16 is connected to the 1 structure 28a. which normally tends to cause the member 28a to rock rearwardly. Consequently, when the latch 13 is released, the struc ture 28a and associated parts will automatically,

end of arm 5|. Thus, when the latch is released, the pressure'on the rocker arm 32 will also be released.

In order to cause the rocker arm to swing rearwardly with the arm 5|, I provide a flexible strap 11. This strap 11 has its upper end connected to an arm 18 that is mounted on the vertically disposed pin 53 carried by member 28a.

The lower end of this strap 11 is connected to o the rocker arm 32 as at 19. This strap is of such a length that when structure 2811 rocks rearwardly the rocker arm will also be swung upwardly. The structure 28a and associated parts will swing rearwardly until the lug 14 of latch l3 10 drops behind the rear edge of plate 15 and the latch member will keep it in its rearwardmost position untildisengaged. When the member 28w rocks rearwardly the rocker arm 32 will also be swung upwardly as explained through 15 the medium of the strap connection Tl. However, upward swinging movement of the rocker arm 32 will be'limited by contact of its rear end with the disk 58.

, In the operation of this machine, the lens 20 blank and the lap are properly positioned on the machine in the manner previously described. The lap mounted on the machine will be .of the proper curve or curves depending upon the curve or curves to be imparted to the lens blank. It 2 may be either toric or cylindrical. The axis or longitudinal center line of the tool or lap is properly lined up relative to the axis or longitudinal center line of the lens blank carrier. The table I2 is adjusted eccentrically of the shaft 30 3. The roller 62 is adjusted eccentrically of the disk 58. The spring 56 and associated parts are adjusted to place the proper downward pressure on the rockerarm 32. Then the machine is started in operation. 35

The table l2 will be caused to travel bodily in a rotary path but it will be prevented from rotating about its axis and, consequently, the

' lap will be prevented from rotating relative to the lens blank. The rocker arm 32 will be moved 40 in a straight line laterally back and forth but in a direction at an angle to the axes of the blank and lap. Since the outer portion of the arm is free to rock, the lens blank and tool or lap will always be infirm engagement with each other. This combination of motions will serve to effectively break up the grinding lines so that the lens produced will be very smooth and polishing will be reduced to a minimum.

The rotary motion of the table may be readily .varied as previously explained. The lateral reciprocatory movement of the rocker arm may also be readily varied. Also, the downward pressure on the rocker arm may be varied. Consequently, the machine may be readily adjusted for grinding any type of lenses.

It' will be apparent from the above description that I have provided a machine for grinding lenses having many desirable features. The machine is of very simple construction and will operate in a very eflicient manner. The combination of motions in the machine results in effectively breaking up the grinding lines so that the lens produced will have a smooth surface and polishing will be reduced to a minimum. This machine is suitable for grinding lenses of any curvature and operates without difiiculty even on strong plus lenses. The machine is designed so that it has a minimum number of moving parts and friction and wear is reduced to a minimum. 7

It will be apparent that the movements of the lap and lens carrier could be reversed. That is, the rotary movement could be imparted to the lens blank carrier and the reciprocatory movement to the tool carrier. In the claims where I state that the tool or lap carrier rotates bodily about an axis and the lensblank carrier reciprocates in a straight line, I also intend to cover the reverse of this.

When I use the term grinding in the specification and claims, I also intend to cover polishing and other similar operations.

Having thus described my invention, what I claim is:

l. A lens grinding machine comprising a supporting structure, a rotatable spindle, alap carrier mounted eccentrically 'on said rotating spin dle and pivotally connected thereto, means for preventing rotation of said lap carrier about its own axis during rotation of said spindle, a rocker arm supported on said supporting structure and arm, said rocker arm being mounted in such a manner as to permit vertical movement thereof, and resilient means for exerting a downward force on said rocker arm.

2. A lens grinding machine comprising a supporting structure, a rotatable spindle carried by said supporting structure, a lap carrier pivotally carried by said rotating spindle and being adjustable eccentrically of said spindle, means for preventing rotation of said lap carrier about its axis during rotation of said spindle, a rocker arm supported on said supporting structure and extending over said lap carrier, said arm comprising two sections one of which may rock on the other, a lens blank carrier carried by one of the sections of said rocker arm, said rocker arm having its inner end keyed to a shaft which is free to rotate, means for moving said shaft longitudinally of itself to cause lateral reciprocation of the rocker arm, said means comprising an eccentric operatively connected to said arm, and resilient means for exerting a downward force on said arm.

3. In a lens grinding machine, a lap carrier, means for mounting a lap on said carrier, said means comprising a shoulder on said carrier with which one edge of said lap will engage, a lug opposite said shoulder having a screw threaded therein, a wedge member pivoted to said lug at the inner side thereof, the inner end of said screw engaging said wedge member and being operable to force the wedge member between said lug and the edge of the lap and to force the opposite edge firmly into contact with said shoulder.

4. A lens grinding machine comprising a lap carrier adapted to have a lap mounted thereon, means for moving said lap carrier in a rotary path, a lens blank carrier adapted to have a lens blank mounted thereon, means for preventing rotation of said lap carrier about its axis during the rotary movement thereof in order to maintain the axis of the lap and the axis of the lens blank in coincidence or parallel to each other at all times, and means for causing said lens blank carrier to move in a straight line which is at an angle to the axis of the lap.

5. A lens grinding machine comprising a lap carrier adapted to have a'lap mounted thereon, means for moving said lap carrier in a rotary path, a lens blank carrier adapted to have a lens blank mounted thereon, means for preventing rotation of said lap carrier about its axis during the rotary movement thereof in order to maintain the axisof the lap and the axis of the lens blank in coincidence or parallel to each other at all times, said means including a pair 5 of rods having one of their ends connected to said lap carrier at diametrically opposed points and their opposite ends connected to a stationary support, and means for causing said lens blank carrier to move in a straight line, one of said rods being shorter than the other so that the straight line motion of the lens blank carrier will be at an angle to a line extending through the points of connection of the rods to the lap carrier.

6. A lens grinding machinecomprising a supporting structure, a rotatable spindle carried by said supporting structure, a lap carrier pivotally carried by said rotatable spindle, means for preventing rotation of said lap carrier about its axis during rotation of said spindle, a rocker arm supported on said supporting structure and extending over said lap carrier, said arm comprising two sections, one of which may rock on the other about its own axis, a lens blank carrier carried by one of the sections of said rocker arm, said rocker arm having its inner end mounted on a shaft, and means for moving said shaft longitudinally of itself to cause lateral reciprocation of the rocker arm, said rocker arm being mounted in such a manner as to permit vertical movement thereof.

7. A lens grinding machine comprising a supporting structure, a rotatable spindle carried by said supporting structure, a lap carrier pivotally carried by said rotatable spindle, means for preventing rotation of said lap carrier about its own axis during rotation of said spindle, an arm supported on said supporting structure and extending over said lap carrier, a lens blank carrier car- 40 ried by said arm, said arm having its inner end mounted on a shaft, and means for moving said shaft longitudinally of itself to cause lateral reciprocation of the arm, said arm being mounted in such a manner as to permit vertical movement thereof.

8. A lens grinding machine comprising a supporting structure, a lap carrier mounted on said supporting structure, means for moving said carrier bodily in a closed path, an arm supported on said supporting structure and extending over said lap carrier, a lens blank carrier carried by said arm, said arm having its inner end mounted on a shaft, and means for moving said shaft longitudinally of itself to cause lateral reciprocation of the arm, said arm being mounted in such a manner as to permit vertical movement thereof.

9. In a lens grinding machine, a supporting structure, a rotatable spindle, a table mounted on said spindle and being pivotally connected thereto, means for preventing rotation of said table about its own axis during rotation of said spindle, said means comprising a pair of rods, said rods having one of their ends freely disposed in sockets at diametrically opposed points on said table, the opposite ends of said rods being freely disposed in sockets formed in a pair of arm members, both of said arm members being connected to a single member rotatably mounted on a stationary structure, and resilient means for normally maintaining the ends of the rods in said sockets.

10. In a lens grinding machine, a supporting structure, a rotatable spindle, a table mounted on said spindle and being pivotally connected theretO, means for preventing rotation of said table about its own axis duringrotationfof said spindle, said means comprising a pair of rods, said rods having one of their ends connected to said table at diametrically opposed points, the opposite ends of said rods being connected to a pair of arms, said arms being carried by a single member mounted for rotationron a stationary structure, a lens blank carrier mounted on said supporting structure, means for moving said carrier in a straight line, said rods being of such lengths and so disposed that the straight line movement of said lens blank carrier will be at an angle to a, line passing through the diametrically opposedpoi-nts at which said rods are connected to said table.

11. A lens grinding machine comprising a supporting structure, a rotatable spindle carried by said supporting structure, a lap carrier pivotally carried .by said rotatable spindle, means for preventing rotation of said lap carrier about its axis during rotation of said spindle, said means comprising, a pair of rods, said rods having one of their ends connected to said table at diametricalrotation on said supporting structure, an arm supported on said supporting structure and extending over said lap carrier, a lens blank carrier carried by said arm, said arm having its inner end mounted on a shaft, and means for moving said shaft longitudinally of itself to cause lat eral reciprocation of the arm, said rods being of such lengths and so disposed that a line passing through the diametrically opposed points at which said rods are connected to said lap carrier will be at an angle to said shaft.

12. In a lens grinding machine, a supporting structure, a lap carrier mounted on said supporting structure, means for moving said carrier bodily in a closed path, an arm supported on said supporting structure and extending over said lap carrier, said arm comprising a forward portion disposed at a higher level than the rear portion thereof, a lens blank carrier carried by the for ward portion of said arm, the rear portion of said arm lying substantially in the same plane 20 as said lap carrier, said arm being mounted for vertical movement, and a thrust member for exerting a downward force on said arm, said thrust member applying the force on the rear portion of the arm at a point substantially level with the lap carrier.

LOWELL L. HOUCHIN.

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