US1520094A - Lens-grinding machine - Google Patents

Description

Dec. 23, 1924. 1,520,094

. L G. SIMPSON LENS GRINDING MACHINE Filed Nov, 30, 1918 ulmmulu l lllllllllllfillIlllllllllllllllllllllll lllllllllllillll IIIEIIII ZZsATTORNEYS Z9 INVETNJ'OR w Z6072 lfim as'orz I 9 BY I v.

Patented Dec. 23, 1924.

LEON Gr. SIMPSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO BAUSGH & LOMB OPTICAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

LENS-GRINDING- MACHINE.

Application filed November 30, 1918. Serial No. 264,851.

- citizen of the United States, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Lens- Grinding Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to lens grinding 1nachines, and more particularly to that class of machines in which a lens blank is mounted on a lens carrier and rotated in contact with an abrading lap which is also rotated. The object of my invention is to provlde an improved adjustable throw crank for reciprocating the lens blank on the grinding lap during the grinding operation and which can be accurately adjusted for lenses and laps of different diameters. A further object of my invention is to provide an adjustable throw crank which is held in adjusted position by means of a friction clutch and which is easily adjusted by means of a finger piece.

In the drawings:

Fig. 1 is a front elevation of a portion of a lens grinding machine embodying one form of my invention, parts being broken away to expose the underlying parts;

Fig. 2 is a plan view of the overthrow crank with connected parts detached from the machine Fig. 3 is an enlarged section on the line 2 -2 of Fig. 2;

Fig. 4: is a section on line 4 9 of Fig. 3 somewhat reduced;

Fig. -5 is a perspective view of'a friction plaite forming a part of my construction, an

Fig. 6 is a plan view of the scale and cooperating pointer, parts being sectioned away for clearness.

Similar reference characters refer to the same parts in all the views of the drawings.

I have shown my invention applied to a lens grinding machine which comprises a table or support 1 in which is rotatably supported a shaft 2 extending upwardly through the table and driven by any suitable source of power, not shown herein. A lens grinding or abrading lap or polishing shell 3 is detachably supported on the upper end of the shaft 2. This construction permits a lap or shell to be substituted for one in the machine when lenses of difierent diameters or curvature are to be ground. Cooperating with the lap 3 is a lens block or carrier 4 to which a lens blank 5 to be polished or ground is secured by means of cement or suitable plastic material. The lens carrier is detachably connected with a lens carrying shaft or spindle 6 which is journaled in an overhanging arm 7. The overhanging arm 7 is pivoted'in a yoke 8 permitting it to swing upwardly in a vertical plane to raise the lens carrier from the grinding lap and at its outer end may be provided with a handle 9 by which it may be manipulated. The yoke or bracket 8 is secured to a post 10 mounted on a support 11 on the table 1. At its upper end and Within the hollow overhanging arm 7 the shaft 6 is provided operatively connected by means of a belt or noiseless chain with a similar pulley or sprocket wheel on the upper end of a shaft or spindle 12-rotatably supported in the table 1 and extending upwardly therefrom through the hollow post 10 and its support 11. At its lower end and beneaththe table 1, the shaft 12 has a sprocket 13 secured thereto by which the shaft is driven by means of a noiseless chain 14 which connects the sprocket with a sprocket 15 secured to the shaft 2. The support 11 is adjustably secured to the post 10 by means of a clamp, 16 and has a bearing on the upper surface of the table 1.

Secured to the shaft 12 is a pinion or gear wheel 17 which meshes with a gear 18 keyed to the end of a shaft 20, which has a bearing in the table 1. To the upper end of the shaft 20 is secured an adjustable throw crank device comprising a clutch member 21 provided with a plurality of openings or rec'esses 22 in its upper surface six being shown in the formillustrated. Seated in each of the recesses 22 is an expansion coil spring 23 which projects above the upper surface of the member 21, and engages a friction plate 24;. The plate 24 is provided with, a pair of projections or lugs 25 which are seated in a pair of recesses 26 in the clutch member 21 and prevent relative rotary movement between the plate and clutch member. The

75 with a pulley or sprocket wheel which is I clutch member 21 is seated in a cooperating clutch member 27 in the form of a cup and having a ring 28 secured to its open end by means of screws 29 and serves to hold or re tain the cup member in operative position on the member 21. Seated in tapped openings in the wall of the cup member 27 is a pair of set screws 30 which are adapted to frictionally engage the plate 24. By adjusting the set screws 30 the tension of the springs 23 may be varied which in turn changes the pressure on the friction surfaces between the set screws 30 and the plate 24 and also between the ring 28 and clutch member 21. The clutch member 21 is mounted eccentrically of the shaft 20 and the clutch member 27 is formed eccentrically of the end of an upwardly extending shaft 31 having a finger piece or handle 32 keyed or otherwise secured thereto at its upper end. A, sleeve or element 38 is journaled on the shaft 31 between the member 27 and the finger piece 32 and has an internally threaded boss 3st projecting from one side thereof. A connection in the form of a screw 35 is threaded in the boss 34 and into a boss 36 formed on a sleeve 37 which has a bearing on a post 38 provided therefor on an outwardly projecting bracket 39 formed on the sleeve 11.

In operation, the shaft 20 is rotated through the gears 17 and 18 which motion is transmitted through the clutch devices to the member 27, which imparts an axial reciprocatory motion to the screw 35 to reciprocate the sleeve 10. The construction is such that the movement of the sleeve or post 10 serves to reciprocate the overhanging arm 7 to move the lens blank back and forth over the surface of the grinding lap. By turning the clutch member 27 to vary the eccentricity of the shaft 31 relatively to the shaft 20, the extent of movement or throw of the lens carrier relatively to the grinding lap is also varied, thus adapting the throw of the lens carrier to grinding laps of different diameters and adapting the machine for grinding lenses of different diameters. By releasing the clamp 16, the connection between the members 11 and 10 is broken, permitting the member 11 to reciprocate independently of the member 10 and thus rendering the adjustable throw crank devices inoperative.

In order to facilitate adjustment of the crank for different grinding laps or lenses of different diameters, a pointer 12 may be secured to the clutch member 21 which extends outwardly, upwardly and inwardly to cooperate with a suitable scale 13 on the up per surface of the member 27. The screw 35 may be provided with a knurled finger piece 44 whereby the screw may be turned to properly' center the lens carrier on the grindinglap. In order to prevent the formation of striations in the grinding of the lens due to variations in the hardness and sizes of the particles of the abrasive material, the gears 17 and 18 are formed of such sizes that in all positions of adjustment of the adjustable crank, the surface relations between lens carrier and grinding lap are constantly changed so that a large hard particle will not retrace its path on the lens blank causing the formation of striations.

While the invention has been disclosed embodied in a machine having the lens carried by the reciprocating member, it will be un derstood that the invention is also adapted to those machines in which the grinding lap is reciprocated or in which the grinding lap is located above the lens carrier, since such variations in arrangement of parts are old and well recognized in the art.

Having described my invention what I claim and desire to secure by Letters Patent 1. In a lens grinding machine, the combination with a lens carried and a grinding tool one of which parts has a to and fro movement relative to the other, of driving means, a clutch disk rotated eccentrically by said means, a second clutch disk in adjustable frictionally driven engagement with said first disk, and means connected with the movable one of said parts eccentrically connected with said second disk for elfectingsaid to and fro move ment, said disks being adjustable relative to each other to vary the amplitude of said to and fro movement.

2. In a lens grinding machine, the combination with a lens carrier and a grinding tool, one of said parts having a to and fro movement relative to the other, of

mechanism for driving said movable part comprising an eccentrically rotated, substantially disk-shaped member, a second member provided with bearing means disposed eccentrically thereof, and adjustable spring actuated means yieldably connecting said members to provide for transmission of driving force and for adjustment of one of said members relative to the other to vary the amplitude of movement of said movable part. 7

3. In a lens grinding machine, the combination with a lens carrier and a grinding tool, one of said parts having a to an fro movement relative to the other, of mechanism for driving said movable part comprising an eccentrically rotated member, a second substantially disk-shaped member having peripheral means for rotatably embracing opposite sides of the first member and having also an eccentrically disposed bearing means, adjustable spring actuated means yieldably connecting said members to provide for the transmission of driving force and for relative adjustment of said members to vary the throw of said bearing means, and means adjustably connecting said bearing means and said movable part.

4. In a lens grinding machine, the combination with a lens carrier and a grinding tool, one of said parts having a to and fro movement relative to the other, of mechanism for driving said movable part comprising a pair of disks, one having means for rotating the same eccentrically and the other having an eccentric element, adjustable frictional means yieldably connecting said disks to provide for transmission of driving force and for relative adjustment thereof to vary the throw of said element and adjustable link means releasably connecting said element and said movable part.

5. In a lens grinding machine, the combination with a lens carrier and a grinding tool, one of said parts having a to and fro movement relative to the other, of mechanism for driving said movable part comprising an eccentrically rotated, substantially disk-shaped member, a second substantially disk-shaped member provided with eccentric bearing means and with peripheral means for rotatably embracing opposite sides of said first member, a substantially plate-like means rotating with one of said members and spring pressed toward the other, adjustable contact means on the other member for yielding engagement with said plate to transmit driving force and provide for relative adjustment of said members to vary the throw of said bearing means, and a connection between said bearing means and said movable part.

LEON G. SIMPSON.

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