US761207A - Machine for grinding lenses. - Google Patents

Description

PATENTED MAY 31, 1904.

F. M. CLARK. v MACHINE FOR GRINDING LENSES.

APPLICATION FILED FEB. 17, 1904.

2 SHEETBBHEET 1.

iwo MODEL.

W/E/JTU PCLWJLM maria I No. 761,207. 'PATBNTED'MAY a1, 1904,

I P. M. (IL-ARK.

MACHINE FOR GRINDING LENSES.

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in the claims.

UNITED STATES rammed May 31, 1904.

PATENT 2 OFFICE.

FRANK M. CLARK, OF TILTON, NEW HAMPSHIRE.

SMACHINE FOR GRINDING LENSES.

SPECIFICATION forming part of Letters Patent No. 761,207, dated. May 31, 1904.

v Application filed February 17, 1904. Serial No. 194,092. (No model.)

Be it known that I, FRANK M. CLARK, a citizen of the United States, residing at Tilton, in

the county of Belknap and State of New Hampshire, have invented new and useful Improvements' in Machines for Grinding Lenses, of which the following is a specification;

This invention relates to a machine for grinding lenses and in the adaptation of my invention hereinafter described, and set fort-h lens, saidconvex surface having a different radius of curvature longitudinally from the radius of curvature upon which it is formed laterally thereof.

The object of the invention is to providea simple and easily-operated machine which will i automatically adjust itself to grind with'ac-;

curacy and nicety lenses of different radii of curvature. I The invention consists, 1n a machine of the character described, of a carrier, a holder for a lens pivotally supported upon said carrier, a statlonary grinder, means to press said lens against said grinder, and mechanism pivotally connected to said carrier whereby said holder.

is moved in a curvilinear path over the surface of said grinder, the median pivotal line of saidholder extending transversely of and intersecting a portion of said grinding-surface. a i

The invention, again, consists in the combination and arrangement of parts set forth in the following specification, and particularly pointed out in the claims thereof.

Referring to the drawings, Figure 1 is a side elevation of my improved machine for grind.

ing lenses. Fig. 2 is a section, partly in elevation, taken on line 2 2 of Fig. 1 looking toward the left in said figure. Fig. 3 is a section,=partly in elevation, taken on line 3 3 of Fig. 2; Fig. 4 is a detail plan of the carrier as viewed inthe direction of the arrow a, Fig.

1; Fig. 5 is a front elevation in detail of the lens-holder viewed in the direction of the ,arrow 6, Fig. 1.,-

Like numerals refer,to like parts throughout the several views ofthe drawings.

' In the drawings, 10 is the frame of my im- The machine is particularly adapted to grind a convex surface upon a toricproved'lens-grinding machine, which may be ofany suitable construction and shape. 11 is a stationary grinder, preferably constructed of castiron, supported upon setscrews 12 12, having screw-threaded engagement with braces 13 13, fast to the frame 10. The grinder 11 has a concave inner surface 14 corresponding to the convex form which it is desired to impart to the lens to be ground. In the particular form of grinder illustrated in the drawings the longitudinal curve 15 of the concave surface 14 is described from the center 16 of a stay-rod 17 by means of which the two sides of the frame 10'are fastened together. Said side frames 10 are further stiffened and fastened together by the braces 13. Theconcave inner surface 14 is formed upon a shorter curve 18 at right angles to the longitudinal curve 15, as seen in Fig. 2, said curve 18 being described from the center 19, this being the configuration of the interior surface of the grinder 11, and in order to impart the desired form to the lens to be ground it will be seen that the mechanism by which the lens is passed over said surface 14 during the grinding operation, as hereinafter described, must yield and conform itself to the different positions of said lens, so that the lens -as it is pressed against and moved around over said concave surface 14 in a series of curves will not be tipped up upon its edges, but will be subjected to a constant and even pressure.

The lens 20 is fastened to a plate 21, which is maintained in a fixed relation to a holder 22 by pins 23,fast to said holder and projecting into said plate. The holder 22 is shown in detail in Fig. Sand consists of a central portion 24 and two curved side arms 25 25. Said side arms are pivoted at 26 26 to a carrier 27.

'It will be noted that the median pivotal line passing through the center of the pivots 26 intersects the portion of said grinding-surface means of a ball-joint 28 to the rocker-arm 29, ,said rocker-arm being pivoted upon the stayrod 17. The rocker-arm 29 is prevented from moving longitudinally upon said stay-rod by collars 30 30, fast to said stay-rod, and consists as a whole of a casting 31, provided with a recess 32, into which a rod 33 projects, said rod being provided with a spherical end to [it in a corresponding recess formed in the car rier 27 and adjustably fastened to the casting 31 by a set-screw 34, so that the distance from the center of the ball-joint to the center of the rod 17 may be varied to suit different radii of curvature for differentlenses. The lower end of the carrier 27 is provided with a crank-pin 35,fast thereto, which projects into a suitablyshaped hole 36 formed in a crank-arm 37, fast to a shaft 38, journaled to rotate in asleeve 39, constituting abearing therefor. The sleeve 39 is provided with a grooved flange 40, constituting apulley, and is journaled to rotate in a bracket 41, fast to the base 42. It will be noted that the median center lines of the shaft 38 and of the bearing 39 converge, so that said shaft is eccentrically journaled in the pulley 40. The lower end of said shaft 38 has a pulley 43 fast thereto. Both of the pulleys 40 and 43 are preferably driven by round leather belts; The carrier 27 has the upper end thereof extended, forming an arm 44, which is connected by a spring 45 to a stationary pointas, for instance, in this case the stay-rod 17. It will be noted that the action of thespring 45 is to press the lens against the concave inner surface 14 of the grinder 11 with a yielding pressure by'tipping the carrier 27 upon the ball-joint 28. It will be noted that a line passing through the center of the ball-joint 28 and intersecting the median line of the pivots 26 when prolonged downwardly will intersect the median line of the crank-pin 35 midway between the upper and lower sides of the crank-arm 37. The carrier 27, with its crank-pin 35, constitutes, in efiect, a link, one of the pivots of which is located above the grinder 11viz., on the ball-joint 28and the other below said grinder in the crank-arm 37. In Fig. 1 broken lines y, g and y indicate, respectively, the two extreme positions and the central position of the rocker-arm 29, and the broken lines z, .2 and .2 indicate, respectively, the two extreme positions and the central position of theholder 22, as indicated by a plane extending through the median center of the pivots 26 and of the center 16 about which the are 15 is described. When the rocker-arm 29 is in its central position, a line a: a; drawn at right anglesto the line 2 should intersect the line y at the center of the balljoint 28.

The general operation of the mechanism hereinbefore described is as follows: The lens having been attached to the plate 21 by means of tar and resin, the lens is moved about in a series of curves over the concave surface 14 of the grinder 11. Water and emery in the proper proportions are poured into the grinder 11 from time to time, and the pulleys 43 and 40 are rotated by belts, as herei'nbefore described, the pulley 43 being rotated,

preferably, about eight times to one rotation of the pulley 40. The result of the combined rotation of the pulleys 43 and 40 is that the 26 and through the center of the ball-joint 28,

and hence there is no tendency of the holder 22 to tip the lens over upon its edges during the operation of grinding said lens, hereinbefore described.

It will be seen that if the curve 18 is described with a shorter radius than that indicated in the drawings the center 19 would necessarily be'lowered from the position shown in the drawings, and this would change the relative position of the center of the balljoint to the carrier 27. To adapt the machine to lenses of different radii, the ball 28 fits into a hemispherical recess formed in 'a'block 46, which is fastened to the arm 44 by a'screw 47. Holes 48 are provided at different points upon the arm 44, Fig. 3, at the proper location, so

that the rocker-arm 29 may be set for different-curv'ed lenses, the location of the holes 48 being governed by the rule for determining the central position of the ball-joint 28 hereinbefore set forth.

While I have described the median center line of the pivots 26 as intersecting a line connecting thepivotal points of the link-carrier 27, said median center line may be moved slightlysay onesixteenth of an inch--above or below said line without interfering materially with the operation of the machine or detracting from the quality of the work produced thereby, and'I therefore do not wish to limit my invention to a machine constructed with the connecting-line drawn between the pivotal points of said carrier-link exactly intersecting the median center line of the pivots whereby the lens-holder is pivoted to said carrier.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, 1s

1. In a machine for grinding lenses, a rockerarm, a rotary crank, a carrier, constituting a link, one end thereof pivoted to said rockerarm the other to said crank, a holder for a lens pivoted to said carrier, and a stationary grinder against which the surface of said lens is adapted to be pressed.

2. In a machine'for grinding lenses, a rockerarm, a rotary crank, a carrier, constituting a link, one end thereof pivoted to said rockerarm the otherito said crank, a holder for a lens pivoted to said carrier, a stationary grinder against which the surface of said lens is adapted to be pressed, and means to press said lens against said grinder. I

3. A machine for grinding lenses comprising in its construction a carrier, a holder for a lens pivotally supported upon said carrier,

a stationary grinder, means to press said lens anism constructed to impart a curvilinear motion to one end of said carrier, whereby said lens is carried in a curvilinear path over the surface of said grinder.

5. A machine for grinding lenses comprising in its constructiona rocker-arm, a carrier pivoted thereto, a grinder, a holder for a lens pivoted to said carrier, and means to press said lens against the surface of said grinder in combination with a crank connected to said carrier, a shaft fast to said crank, and a rotary sleeve in which said shaft is eccentrically journaled. 1 V

6. A machine for grinding lenses comprising in its construction arocker-arm, a carrier pivoted thereto, a grinder, a holder for a lens pivoted to said carrier, and means to press said lens against the surface of Said grinder; in combination with a crank connected to said carrier, a shaft fast to said crank, a pulley in which said shaft is eccentrically journaled, and independent mechanisms to rotate said pulley and shaft.

7. A machine for grinding lenses comprising in its construction a rocker-arm, a carrier pivoted thereto, a grinder, a holder for a lens said lens against the surface of said grinder; in combination with a crank connected to said carrier, a shaft fast to said crank, a rotary sleeve in which said shaft is eccentrically journaled, and mechanism to rotate said shaft and sleeve at different rates of speed.

8. A machine for grinding lenses comprising in its construction a grinder having a curved grinding-surface, a pivotally-supported carrier, a holder for a lens pivoted to said carrier and adapted to hold said lens against said curved grinding-surface, the median pivotal line of said holder extending transversely of and intersecting a portion of said grindingsurface.

9. A machine for grinding lenses comprising in its construction a grinder having a curved grinding-surface, a carrier constituting a link, one of the pivots of said link located above, the other below, said grindingsurface, and a holder for the lens pivoted to said carrier and adapted to hold said lens against said grinding-surface, the median pivotal line of said holder extending transversely of and intersecting a portion of said grindingsurface.

10. A machine for grinding lenses comprising in its construction a grinder having a curved grinding-surface, a carrier constituting a link, one of the pivots of said link located above, the other below, said grindingsurface, and a holder for the lens pivoted to said carrier and adapted to hold said lens against said grinding-surface, the median pivotal line of said holder substantially intersecting a line connecting the pivotal centers of said link-carrier.

In testimony whereof I. have hereunto set my hand in presence of two subscribing witnesses.

FRANK M. CLARK. Witnesses:

CHARLES S. Goonnve, ANNIE J. DAILEY.

pivoted to said carrier, and means to press

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