US2214361A - Lens grinding machine - Google Patents

Description

Sept. 9 K. c. BURROUGHS 2,214,361

LENS GRINDING MACHINE Filed April 10, 1935 s Sheets-Sheet 1 m m b q no l- Fl G. I

KENNETH C.BURROUGHS INVENTOR ATTORNEY Sept. 10, 1940.

FIG. 2

K. c. BUVRROUGHS 2,214,361

LENS GRINDING MACHINE Filed April 10, 1935 1 3 Sheets-Sheet 2' KENNETH CBURROUGHS INVENTOR ATTORN EY Sept. 10, 1940. K. c. BURROUGHS LENS GRINDING MACHINE Filed April 10, 1935 3. Shee'ts-Sheet 3 KENNETH CBURROUGHS INVENTOR BY m ATTORNEY Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE 2,214,361 LENS GRINDING MACHINE Application April 10,

6 Claims.

The present invention relates to lens grinding and more particularly to an apparatus for grinding and polishing lenses or the like.

One of the objects of the present invention is to provide a new and improved apparatus for grinding and polishing lenses. Another object is to provide an automatic machine for grinding and polishing lenses. A further object is to provide a lens grinding machine having a plurality of abrading stations and means for moving the lens from station to station. Still another object is to provide an improved spindle assembly for an automatic lens grinding machine. A still further object is to provide an improved means for applying pressure to one spindle of a lens grinding machine. A further object is to provide an improved timing mechanism. These and other objects and advantages reside in certain novel features of construction, arrangement and combination of parts as will hereinafter be more fully set forth and pointed out in the appended claims.

Referring to the drawings:

Fig. 1 is a diagrammatic rear view of a lens grinding machine embodying this invention.

Fig. 2 is a diagrammatic top view of same.

Fig. 3 is a side elevation of one of the abrading units. v

Fig. 4 is a vertical section of an abrading tool spindle with parts shown in elevation.

Fig. 5 is a diagrammatic view of the timing mechanism.

One embodiment of this invention is illustrated in the drawings wherein I ll indicates a supporting table upon which are mounted a lens blocking device I l a diamond grinder 12, an emery grinding station l3 and two polishing stations 14 and [5, for example. A rough molded or pressed lens blank I6 is placed in the machine Where it is secured to a block I! and passed through the successive grinding and polishing stages until it emerges finished on one side.

The lens blocking device I I, the structural details of which form no part of this invention, comprises any suitable device for securing the lens blank IE to the block 11. A device which places a small amount of melted pitch on the block l'l, presses the lens blank 16 into this melted pitch and then cools the pitch so as to fix the lens blank l6 rigidly to the block [1, would be satisfactory. The cam l8, mounted on the shaft l9, and the follower 20, carried by the lens blocking device I I, could furnish the power for any necessary moving parts.

The structural details of the diamond grinder l2 likewise form no part of the present invention.

1935, Serial No. 15,623

The grinding tool, which may be of diamond charged copper or the like, is driven at high speed by a motor 21. The lens !6 and block II are carried upon a rotatable and axially movable spindle which is rotated at a slower speed than the tool by a belt 22 driven from a shaft 23. The axial movement of the spindle is controlled by the cam 24 on the shaft [9, and the follower 25.

The structural details of the emery grinding device l3 also form no part of the present invention. This device is described and claimed in the co-pending application of Carl E. Anderson, Serial No. 433,934, filed March 7, 1930. entitled Method and means for abrading lenses", now Patent No. 2,105,175, dated Jan. 11, 1938. The upper spindle of the emery grinder I3 is driven by the belt 26 from the shaft 23. The lower spindle is both rotatable and axially movable and is rotated by the belt 21 from the shaft 23. The lower spindle is moved axially toward and from the upper spindle by the cam 28 on the shaft l9, and the follower 29.

The polishing units 14 and I5 are identical and each comprises a lower driven spindle 30 rotatably carried by a lever 3| which is pivoted at 32 to the table Ill. The spindle 30 has a pin 33 engaging a. slot 34 in the block I] for rotating the lens. A belt 35 serves to drive the spindle 3|! continuously from the shaft 23. The lever 3| carries a follower 36 for engaging a cam 31 on the shaft I 3. From Fig. 3 it is apparent that when the shaft I9 is rotated the cam 31 will cause the lens IE to move away from the abrading tool 38. This lower spindle assembly is substantially the same in the diamond grinder 12, the emery grinder l3 and the ,two polishers l4 and I5. v

The upper spindle assembly comprises a housing 39 secured to a shaft 40 which is rockably mounted upon the top of the table II]. Within the housing 39, a spindle 4! is slidably and rotatably journaled in bearings 42, and this spindle ll detachably carries the abrading tool 38 at its lower end. A bracket 43 secured to the housing 39, carries at its upper end a cylinder 44 in which a piston 45 is slidable. A thrust bearing 46 connects the piston 45 to the spindle 4|. To limit the downward movement of the spindle ll, an adjustable collar 41 is placed'on the spindle 4! between the cylinder 44 and the housing 39. The upper spindles M of the polishing units I l and I 5 are not positively driven but receive their movement from the friction between the lens I6 and the tool 38.

In the case of the emery grinding unit l3 and the two polishing units l4 and [5, it is essential 35 that the abrading tool 38 be held against the lens I 8 with a certain amount of pressure. The upper spindle 4| of each unit is free to slide longitudinally to accommodate different thicknesses of the lens I6 and block I1 and also to take up any wear in the tool 38. Thus when the lower spindle is raised by the action of its cam, the tool 38 and spindle 4| are moved upward by the lens I 8. If, during this movement, the spindle 4| were pressed downward by the pressure necessary for grinding or polishing, the force between the two spindles would be suflicient to break the lens.

The desired pressure between the lens I6 and the tool 38 is obtained by admitting compressed air or other fluid to the cylinder 44. A reservoir 48 for the compressed air has an outlet 49 which connects to a valve mechanism 58. The valve mechanism 58 is controlled by a cam on the shaft I9 so that the air pressure is admitted to the cylinders 44 through the pipe only when the spindle 38 is at, or near, the top of its travel.

The upper spindles 4| of the polishing units I4 and I5 are carried by the rockable shafts 48. These shafts 48 are driven with a slight oscillating movement from the shaft 23 by means of belts 52. Such a slight movement of the tool across the lens gives the polisher a more uniform polishing effect.

The abradant is supplied to the emery grinding unit I3 and the two polishing units I4 and I5 by means of, automatic mechanisms 53 connected by belts 54 to a shaft 55 under the control of an independent motor 56. Compressed air is introduced into each mechanism 53 by an inlet pipe 51 connected to the outlet pipe 49. The structural details of these mechanisms form no part of the present invention but are described and claimed in the copending application of Kenneth C. Burroughs, Serial No. 8,673, filed February 28, 1935 entitled Abradant supplying device", now Patent No.-2,083,'173, dated June 15, 1937.

The lenses I6 and blocks I1 are moved from one station to the next by a plurality of forks 58 mounted upon a. travelling bar 59. This bar 59 moves inward until each fork 58 grasps a lens I8 and block I1. The bar then moves outward, then moves to the left as seen in Fig. 2, then moves inward where the lens I6 and block I1 are removed. The bar 59 then moves outward and returns to its original position. The inward and outward movements of the bar 59 are controlled by the reversible cylinder and piston mechanisms 58 and the lateral movement of the bar 58 is controlled by the reversible cylinder and piston mechanism 6 I. These cylinder and piston mechanisms are operated by pressure from the reservoir 48 and controlled by valves 62, 63, 64 and 65 which are operated from the shaft I9.

When the movement of the lenses from one station to the next is to take place, the valve 85 is opened admitting compressed air through the pipes 66 to the front end of each cylinders 68 thus moving the bar 59 inward. The valve 82 is then opened admitting compressed air to the other end of the cylinders 68 through the pipes 61 moving the bar 59 outward. Valve 64 then admits the compressed air through the pipe 68 to the right hand end of the cylinder 6| as seen in Fig. 2 moving the bar 59 to the left as seen in Fig. 2. Valves 65 and 62 operate as before and then valve 63 opens admitting air to the left hand end of the cylinder 6| through the pipe 59 returning the bar 59 to its original position. The movement of the bar 59 and forks 58, as well as the movement of the lower spindles of the abrading units are all controlled from the shaft I9. The bar 59 and forks 58 move inward and grasp the lens blocks I1 before the lower spindles move downward. As can be seen in Fig. 3, the fork 58 holds the lens I6 and block I1 in the same plane while the spindle 38 moves away from the block I1. When the lens I6 and block I1 are to be left at the next unit, the spindle 38 rises and grips the block I1 and then the fork 58 is withdrawn.

The main drive shaft 23 is driven by a motor 18 which also drives a belt 1| connected to a pulley 12 on the timing mechanism 13. This timing mechanism 13, which is diagrammatically shown in Fig. 5, intermittently drives the control shaft I9 for periodically actuating the cams I8, 24, 28 and 31 and valves 58, 62, 63, 64 and 65 in proper timed relation. The pulley 12 is mounted upon a shaft 14 and drives the shaft I9 through the pulley 15, chain 18, pulley 11, clutch 18, worm 19 and gear 88. The pulley 12 is continuously driven and the intermittent movement on the shaft I9 is obtained by connecting and disconnecting the clutch 18.

The clutch 18 is actuated by a bell crank lever 8| one end of which is connected to the reversible cylinder and piston mechanism 82. Compressed air is admitted to the timing mechanism by a pipe 83 connected to the pipe 49 and from this pipe 83 two branches 84 and 85 lead to the two ends of the reversible cylinder and piston mechanism 82. In the pipe 84, a valve 88 opens to permit the air to enterone side of the cylinder and piston mechanism 82 and move the lever 8| to close the clutch 18 and thus complete the drive from the pulley 12 to the gear 88 and shaft I9.

Mounted upon the shaft 14 is a worm 81 which drives a cam 88 through gears 89, 98, 9| and 92. A lever 93, pivoted at 94 is urged away from the valve 86 by a spring 95. Once in each revolution, the cam 88 engages the lever 93and moves it to open the valve 86 admitting air to the cylinder and piston mechanism 82 to close the clutch 18. As soon as the cam 88 releases the lever 93, the lever 93 is returned to its normal position by the spring 95. In this position the lever 93 opens an exhaust valve 98 which releases the air pressure in the cylinder and piston mechanism 82. The bell crank lever 8|, however, remains in its position with the clutch 18 closed.

The pipe 85 leading to the other end of the cylinder and piston mechanism 82 is controlled by a spring valve 91. This valve 91 is such that in its normal position the pressure line is closed and any pressure in the cylinder and piston mechanism 82 is released. Upon pressing of the stem 98 the pipe 85 is opened admitting compressed air to the cylinder and piston mechanism 82 which serves to open the clutch 18. As soon as the stem 98 is released, it is returned to its original position by a spring, not shown. The bell crank lever 8| remains in its position and the clutch 18 remains open.

It is essential that the shaft I9 always be stopped in exactly the same position and this stopping is accomplished by pressing the valve stem 98. A hammer 99 is pivoted at I88 on the gear 88 and is urged in the direction of rotation of the gear 88 by a spring |8I., The hammer 99 has a notch I82 which is adapted to-be engaged by a trigger I83 pivoted at I84 to the gear 88. A fixed cam surface I85 adjacent the valve 91 serves to hold the hammer 99 during the rotation of the gear 88 so that the trigger I83 is engaged in the notch I82 holding the hammer 99 against the tension of the spring I8 I. As the gear 88 revolves,

3. In an apparatus of the character described a projection I06 on the trigger I03 is engaged by a fixed release member i0! which releases the trigger I03 from the notch I02 permitting the spring lili to move the hammer 99 to strike the valve stem 98 thus opening the clutch.

The worm 81 and gears 89, 90, BI and 92 give a very great reduction of motion between the shaft 14 and the cam 88. Thus the shaft 14 will rotate a large number of times for each actuation of the valve 86 with its engaging of the clutch 18. The motion reduction between the shaft 14 and the shaft i9 is relatively small. In this way, a long abrading time is had while the shaft i9 is still and the transition period is kept small by rotating the control shaft I9 at a good rate when it is actuated.

In operation, the motor 10 drives the main shaft 23 from which the spindles of the abrading units are driven and also drives the control shaft i9 through the timing mechanism 13. When the shaft l9 begins to turn, the pressure on the upper spindles of the abrading units is released and the bar 59 moved inward to grip the lens blocks H. The cams 24, 28 and 31 then move the driven lower spindles and the lens blocks I! are withdrawn and moved to the next abrading unit. The driven lower spindles are then raised, the bar 59 returned to its original position and the valve 50 actuated to renew the pressure on the upper spindles.

From the foregoing it will be apparent that I am able to attain the objects of my invention and provide a new and improved machine for automatically grinding and polishing lenses. Although the parts combine to form a new machine and interact to form a true combination, the separate mechanisms can be used with advantage in other machines. For example, the separate abrading units and the timing mechanism could be used in other machines. Various modifications can, of course, be made without departing from the spirit of this invention or the scope of the appended claims.

I claim:

1. An abrading apparatus comprising a work support, a spindle support in opposed relation to said work support, a spindle slidably and rotatably mounted in said spindle support, a cylinder carried by said spindle support in axial alignment with said spindle, a piston slidably mounted in said cylinder, a thrust bearing connecting said piston and said spindle, and means for selectively introducing pressure into said cylinder to move said spindle toward said work support.

2. In a device of the character described a plurality of lens grinding mechanisms, each mechanism comprising a support, a spindle rotatably mounted in said support, a second support, a second spindle rotatably and slidably mounted in said second support, in substantial alignment with said first spindle, means on one spindle for holding a lens, means on the other spindle for holding an abrading tool, means for rotating one spindle of each mechanism, intermittent means for sliding the slidable spindle of each mechanism toward and from its cooperating spindle, a lens handling device for moving the lens from one grinding mechanism to the next, and a timing mechanism for operating said intermittent means and said lens handling device.

a plurality of lens grinding mechanisms, each mechanism comprising a pair of aligned rotatable spindles, one of which is axially movable, means for moving said spindle axially, means on one spindle for holding a lens and means on the other spindle for holding an abrading tool, means for moving a lens from one grinding mechanism to the next, a continuous drive means for rotating one spindle of each mechanism, an intermittent mechanism driven from said continuous drive means and means for interconnecting the lens moving means and the means for axially moving said spindles to said intermittent means.

4. In a lens grinding machine a plurality of lens grinding mechanisms, each mechanism comprising two spindles rotatably mounted in substantially axial alignment, means on one spindle of each mechanism for holding a lens, means on the other spindle for holding an abrading tool, one spindle of each mechanism being substantially axially movable, a rotatable cam shaft, a cam on said shaft for each movable spindle for moving said spindle axially, a lens shifting device, cylinder and piston means for actuating said lens shifting device to shift a lens from one grinding mechanism to the next, a source of compressed fluid connected to said cylinder and piston means, valves for controlling the flow of said fluid to said cylinder and piston means, motor means. for rotating one spindle of each grinding mechanism, a timing device, means for operating said timing device from said motor means and means for operating said cam shaft and said valves intermittently from said timing device.

5. In a lens grinding machine a plurality of lens grinding mechanisms, each mechanism comprising two spindles rotatably mounted in substantially axial alignment, means on one spindle of each mechanism for holding a lens, means on the other spindle for holding an abrading tool, one spindle of each mechanism being substantiially axially movable, a rotatable cam shaft, a cam on said cam shaft for each movable spindle for moving said spindle axially, a lens shifting device, cylinder and piston means for actuating said lens shifting device to shift a lens from one grinding mechanism to the next, a source of compressed air, valves for controlling the flow of said compressed air to said cylinder and piston means, operative interconnections for controlling said valves from said cam shaft, a motor for driving one spindle of each mechanism, a shaft driven by said motor, a driving connection between said motor and said cam shaft, a clutch in said driving connection, means for causing disengagement of said clutch and means for causing reengagement of said clutch.

6. In a lens grinding machine, a support, a spindle freely rotatable in said support, a grinding lap eccentrically mounted on one end of said spindle, a second support, a second spindle rotatably mounted in said second support in opposed relation to the first-named spindle, a lens carrying support mounted on said second spindle for holding a lens against said lap and meansfor driving said second spindle.

KENNETH C. BURROUGI-IS.

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