US2977724A

US2977724A - Lens surfacing machine

Info

Publication number: US2977724A
Application number: US835599A
Authority: US
Inventors: William J Kennedy; Stanley F Hostetler
Original assignee: Textron Inc
Current assignee: Textron Inc
Priority date: 1959-08-24
Filing date: 1959-08-24
Publication date: 1961-04-04
Anticipated expiration: 1978-04-04

Description

April 4, 1961 w. J. KENNEDY ETAL LENS SURFACING MACHINE Filed Aug. 24, 1959 FIG.

4 Sheets-Sheet 1 INVENTORS WILLIAM J. KENNEDY AND BY STsNLEY F. HOSTETLER April 4, 1961 w, EN ED ETAL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 Sheets-Sheet 2 m" cu Q o E INVENTORS WILLIAM J. KENNEDY AND BY STANLEY F. HOSTETLER April 1961 w. J. KENNEDY ETAL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 SheetsSheet 3 ||o 67 29\ IO? no I08 107 I09 1 Q II H5 128 II ||2 98 93 EL '97 95 |2| 9e 92 I20 98 v 9 if 47 INVENTORS WILLIAM J. KENNEDY AND STANLEY E HOSTETLER April 4, 1961 w. J. KENNEDY EI'AL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 Sheets-Sheet 4 LO Q I Q L r T L S2 & g u.

IN V EN TORS WILLIAM J. KENNEDY AND STANLEY F. HOSTETLER United States Patent "ice j 1 2,917,724 LENS SURFACING MACHINE William J. Kennedy, Geneva, and Stanley F. Hostetler,

Phelps, N.Y., assignors to Textron Inc., Providence. R.I., a corporation of Rhode Island Filed Aug. 24, 1959, Ser. No. 835,599 7 Claims. (Cl. 51-124) The present invention relates to machines for surfacing lenses, "and more particularly to machines for lapping approximately spher'ical surfaces on lenses.

In conventional lens lapping machines, a convex or a concave lap, depending upon whether the lens surface thatis to be lapped is concave or convex, is engaged with the workpiece under pressure, and one or the other is rotated while a relative swinging movement is effected between the two. In practically all lens surfacing machines that have been built to date the oscillation is achieved by a crank or eccentric drive. An eccentric or crank produces a simple harmonic motion. The velocity starts at zero and builds up to a maximum when the crank has rotated 90, and then the velocity decreases to zero again through the other 90 of rotation of the crank. With this type of drive there is a definite dwell at both ends of the stroke. When wear develops in such a machine this dwell at the ends of the strokeis amplified. As a result zones or irregularities are produced on the lens surface.

. One object of the present invention is to provide a lens surfacing machine in which the oscillatory motion is ef fected in such wise as-to reduce to a minimum the possibility of formation of zones or irregularities on the lens surface. To this end it is a further purpose of the invention to provide a lens surfacing machine in which the velocity of the oscillatory motion is constant throughout the stroke in either direction and the reversal at opposite ends of the stroke is practically instantaneous.

Another object of the invention is to provide a machine of the character described in which the pressure between the lens and lap is always applied to the lens in a direction normal to the lap curvature.

Another object of the invention is to provide a machine of the character described in which the position of the Y 7 axis of oscillation and the extent of oscillation, as required by the particular lap in use, can very readily be adjusted; Another object of the invention is to provide a machine of the character described which will'be precise in operation, rigid in construction, and eificient in operation.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.

In the drawings: l Fig. 1 is a part side elevation, part vertical sectional view of a machine built according to one embodiment of this invention;

Fig. 2 is a plan view of this machine; Fig. 3 is a rear'elevation of the machine, part being broken away and shown in section; i

Fig. 4 is a front elevational view illustrating diagrammatically the set-up and principle of operation of the machine illustrated when lapping the concave'surface of one type lens; i

Fig. 5 is a plan view further illustrating diagrammatically the operation of the machine;

Fig. 6 is a diagrammatic view, similar to that of Fig. 4, showing a set-up for lapping the concave surface of a lens having a smaller, more sharply curved surface than the lens shown in Fig. 4; and

Fig. 7 is a diagrammatic view illustrating the set-up and operation'of the machine in lapping a convex surface on alens.

2,97?,'i24 Patented Apr. 4, 1961 Referring now to the drawings by numerals of reference, 10 denotes the base or frame of the machine. Secured by means of screws 21 (Fig. 1) in an opening 11 in the base 10 is a support 12 in which there is journaled on 5 spaced anti-friction bearings 13 and 14 a tool spindle 15. The tool spindle is adapted to be driven from a motor 16, which is mounted on top of the frame, through the'armature. shaft 17 of the motor, a pulley 18, the belt 19, and a pulley 20. Pulley 20 is keyed or otherwise fastened to 10 the lower end of the tool spindle 15. The lap for lapping the lens is keyed, or otherwise fastened, to an adapter 26 that is threaded, or otherwise secured to the spindle 15. A guard 27 is fastened to the adapter and is secured by the adapter to the spindle 15 to cover the 10 top of the spindle to prevent abrasive or other grit from getting into the spindle bearings; and a guard 29 is secured to the support12 around the tool and lens to prevent splattering of the abrasive compound.

Mounted on the base 10 to be adjustable laterally recti- 20 linearly thereon is a column 30 (Figs. 1 and 2). This column is adapted to be adjusted laterally on the base on 1 which pass through elongate slots 39 in the column, and

which thread into the base. 30 Journaled in the column 30 is a trunnion 45 (Fig. 1).

This trunnion is adapted, to be secured in any position to which it is adjusted angularly about its axis, by a clamp plate 48 which is adapted to be held in clamping engagement witha fiat surface, formed on the rear of the column 30, by a bolt 46 that threads into the trunnion.

The plate 48 is held against rotational movement relative to the trunnion by means of a dowel pin 47.

Secured to the trunnion to be adjustable therewith about theaxis of the trunnion is a bracket 50. The- 4 bracket 50 is held against axial movement relative to the trunnion by a split ring 51 which engages in a peripheral recess in the trunnion. It is adapted to be secured against movement angularly relative to the trunnion by a setscrew 53 which engages in an elongate recess 54 in the 45 periphery of the trunnion.

Mounted on the bracket 50 for oscillatory movement thereon about an axis at right angles to the axis of the trunnion is a carrier 60. The bracket 50 has two parallel ears 61 and 62 integral with it and projecting 50 forwardly from it. Secured in these cars 61 and 62 with a pressed fit are two axially aligned

trunnion pins

63 and 64. The carrier 60 is mounted on these trunnion pins by means of

bushings

65 and 66 which are mounted in spaced ears 73 and 74 formed integral with and projecting rearwardly from the carrier. The nut 67, which threads into one ear 73 of the carrier, serves to hold the carrier in position on the bracket 59. This nut 67 is provided with a plurality of angularly spaced peripheral notches 68, which are adapted to be engaged by the head 0 of a screw 69 to secure the nut in any adjusted position.

The screw 69 threads into the rocker member 60.

Mounted on the carrier for rectilinear adjustment thereon axially of the axis of oscillation of the carrier is an air cylinder 70. This cylinder is adjustable on the front face of the carrier and is guided in its adjustment by a key or gib 71 (Fig. 2). It is adapted to be secured to the carrier in any adjusted position by bolts 72 which pass through elongate slots in the carrier and thread into the base of the air cylinder.

Reciprocable in the air cylinder is a piston 75 (Fig. 1) which is secured to a piston rod 76. This piston rod projects beyond both sides of the piston. It extends at its upper end through a guide bushing 77 and through a suitable packing seal 79 in the end cap 78 of the cylinder. It has a stop block 80 secured to its upper end to limit its downward movement. It extendsat its lower end through a guide bushing 81 and through a conventional seal 82 in the end cap 83 of the cylinder. The end caps 78 and 82 are secured to the cylinder body by screws or in any other suitable manner. At its lower end the piston rod 76 has a ball-headed member 85 threaded therein. The ball head of the member 85 is adapted to engage in a complementarily-shaped socket formed in a lens block 86, to which the lens L, which is to be lapped, is secured by pitch or in any other suitable manner. The ball head of the member 85 and the socket of the lens block form a ball and socket joint. Air pressure is adapted to be applied to the upper face of the piston 75 to hold the lens in engagement with the lap during the operation of the machine.

Oscillatory motion of the carrier 60 is effected by reciprocation of a piston 90 (Fig. 3) in a cylinder 91. The piston is secured to a piston rod 92 which projects at both ends through the end caps 93 and 94, respectively, of the cylinder. The piston rod slides through bushings and sealing members in these end caps. The piston rod engages at opposite ends with two stop screws 95 and 96 that are threaded to the arms of a yoke 97, and secured therein by nuts 98.

The hydraulic cylinder 91 is supported from the bracket 50, being secured to the bracket by screws 99 that thread into the base of the cylinder. The bracket is formed with spaced

guides

100 and 101; and the base of the cylinder 91 is secured to these guides by the screws 99. The yoke 97 moves in its reciprocatory movement between the

guides

100 and 101. Fastened to the yoke 97 is a stud or pin 105 on which there is mounted a block 106. The carrier 60 is furcated at its rear end; and the block 106 engages in the recess 104 between the furcations of this member, thus transmitting the reciprocatory motion of the piston 90 to the carrier 60 to rock that member about the axis of the trunnion pins 63 and 64. The yoke member 97 has aligned, spaced lugs 107 projecting rearwardly therefrom. Mounted to rotate in these lugs is a screw shaft 108, which is adapted to be manually rotated by means of the knob 109. The shaft has right and left hand threads, respectively, at opposite sides of its longitudinal center. Adjustably mounted on this screw shaft 108 are two knurled blocks 110, which are adapted to be adjusted along the shaft a desired distance apart. These blocks are positioned to engage the lug 111 of a cam plate 112, which is slidably mounted on the rear face of the base of the cylinder 93, and which is secured thereto by bolts 114. These bolts thread into the base, and pass through elongate slots 115 in the cam plate. The cam plate is formed with a bottom cam surface adapted to engage the plunger of a conventional limit switch 120 that is wired in electric circuit with the solenoid of a conventional solenoidoperated valve (not shown) that controls the direction of flow of the hydraulic motive fluid to the cylinder 91. The limit switch 120 is mounted on a plate 121 which is secured to the bracket 50 by the bolts or studs 114. A coil spring 122, which surrounds each bolt 114, is interposed between a shoulder on the bolt and the plate 121 to frictionally hold the cam plate 112 in position.

The hydraulic motive fluid may be supplied from the line common to a plurality of machines, or from a pump 124 (Fig. 1) mounted on top of the motor 16 and driven from the armature shaft of the motor. The armature shaft of the motor projects at both ends beyond the motor housing.

In operation, the bracket 50 is adjusted with trunnioninsure that the air pressure is applied normal to thelap surface. The column 30 is also adjusted laterally on the base 10 so that the center of the stroke of oscillation of carrier 60 about the axis of

pins

63 and 64 will be approximately mid-way between one edge of the lap and the axis of the lap so that the lens will move in its oscillation from one edge to the center of the lap back and forth.

Fig. 4 illustrates diagrammatically the set-up and operation for lapping a concave surface on a lens L. The lens L is cemented or otherwise secured to the lens block 86, and a lap 25 is used that has a convex generally spherical operating surface 125 centered at 126 on the axis 127 of the lap spindle 15. For lapping this lens L the column 30 is adjusted laterally on the base 10 by a distance 130 so that the pivot axis 131 of the bracket 50 (the axis of trunnion 45) is offset by this distance 130 from the axis 127 of the lap spindle. Then the bracket 50 is adjusted angularly about the axis 131 until the center line 132 of the piston 76 is normal to the lap surface 125 and intersects the axis 127 of the lap spindle in the center 126 of the lap surface. When the machine is operating, then, the reciprocating piston 90 rocks the carrier 60 back and forth about the axis 135 (Fig. 5) of the

pins

63 and 64, causing the air cylinder and the lens to oscillate through an angle 136 about this axis 135. The air pressure on the top of piston 75 holds the lens in lapping engagement with the lap during this rocking motion, the piston 75 moving in cylinder 70 to maintain this lapping engagement. The piston 90 operating through the yoke 97, and the nuts 110 shifts the cam 112 at opposite ends of the movement of the piston to operate the limit switch 120, which reverses the valve that controls the direction of application of the fluid pressure to the piston 90.

The air pressure is maintained on piston 75 during the entire operation of the machine. It may be supplied from any suitable source of compressed air through a conduit (not shown) that threads at 102 into cylinder 70. The air pressure on the top of the piston 75 can be released when desired through this same opening 102. A conventional valve may be used for this purpose.

For a lens L (Fig. 6), which has more concavity, a lap 25' will be used which has a shorter radius of curvature, that is, greater convexity. Here the column 30 will be adjusted laterally on the base 10 a distance 140 less than the distance 130 so that the axis 131 of trunnion 45 will be offset this distance 140, and then the cylinder 70 is tilted about this axis 131 so that the center line 132 of piston rod 76 will be normal to the operating surface of the lap and will intersect the axis 127 of the lap spindle in the center 146 of curvature of the lap surface 145. The amount of oscillatory movement of the lap is again determined by adjustment of the nuts 110. A graduated dial 128 (Figs. 2 and 3) may be secured to the spindle 108 to read against a pointer 129 that is fastened to one of the lugs 107 so that this adjustment can be made precisely. As before in the lapping operation the lap will rotate on its axis, and the lens will be oscillated about an axis 135 parallel to the axis 127 of the work spindle 76, the amount of oscillation depending upon the positions of the nuts 110.

For lapping a convex lens, such as shown at L in Fig. 7, a concave lap 25" will be employed whose lapping surface is denoted at 155. In this case the column 30 is adjusted laterally to the right, as viewed in Fig. 7, of the axis 127 of the lap spindle by a distance 150, and the bracket 50 is adjusted about the axis 131 of the trunnion 45 until the center line 132 of the piston 76 intersects the axis 127 of the lap spindle in the center 156 of curvature of the operating surface of the lap. Then, as before, lapping is effected by rotating the lap on its axis in engagement with the lens while the lens carrier 60 is oscillated about the axis 135 (Fig. 5) of the carrier.

From the preceding description it will be seen that because the oscillation of carrier 60 is effected by a recipe.

rocable hydraulically-actuated piston 90, we have provided a very simple machine with a velocity of stroke that is constant throughout its entire length, and in which the reversal of the oscillating motion at the ends of the stroke is practically instantaneous. Thus, it will be seen, that we have provided a machine with which it is possible to produce lenses that arefree of zones or aberration.

While the invention has been described in connection with a specific embodiment thereof, however, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the'invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention, what we claim is:

1. A lens surfacing machine comprising a base, a column adjustable rectilinearly in said base, a bracket mounted on said column for angular adjustment thereon, a carrier mounted on said bracket for oscillation about an axis extending at right angles to the axis of adjustment of said bracket, a spindle mounted in said base, and a spindle mounted in said carrier, one of said spindles being adapted to carry an abrading tool and the other spindle being adapted to carry a lens, one of said spindles being rotatable and the other of said spindles being axially reciprocable, said bracket being adjustable angularly on said column about an axis extending at right angles to the direction of lateral adjustment of said column, so that the axis of the spindle which is mounted on said carrier means for rotating one of said spindles on its axis, fluidpressure operated means for constantly urging the other spindle axially toward said one spindle to hold the lens and abrading tool in operative engagement, and means for oscillating said carrier on its axis simultaneously with the rotation of said one spindle.

2. A lens surfacing machine comprising a base, a tool spindle journaled in said base, means for securing an abrading tool to said spindle at one end thereof, a column adjustable rectilinearly on said base in a direction at right angles to the axis of said spindle, a bracket mounted on said column for adjustment thereon about an axis at right angles both to the axis of said spindle and to the direction of adjustment of said column, a carrier mounted on said bracket for oscillation about an axis at right angles to the axis about which said bracket is adjustable, a rod mounted on said carrier for movement in a direction parallel to said axis of oscillation, means for securing a workpiece to the end of said rod adjacent the tool, means for constantly urging said rod in a direction to hold said workpiece and tool in operative engagement under pressure, means for rotating said spindle, and means for simultaneously oscillating said carrier.

3. A lens surfacing machine comprising a base, a tool spindle journaled in said base for rotation thereon, means for securing an abrading tool to said spindle, a cylinder, a piston reciprocablein said cylinder, a piston rod secured to said cylinder and projecting at one end beyond one end of said cylinder, means for securing a lens to the projecting end of said piston rod, means for adjusting said cylinder on said base so that the longitudinal center line of said piston rod intersects the axis of said spindle in a point offset from the zone of engagement of the tool and lens, means for applying air pressure to one end of said piston to hold said tool and lens in engagement under pressure, means for rotating said spindle, and means for simultaneously oscillating said cylinder about an axis parallel to the longitudinal center line of said piston rod.

4. A lens surfacing machine according to claim 3 in which said oscillating means comprises a second cylinder, a second piston reciprocable in said second cylinder, and means for applying hydraulic pressure alternately to 6 opposite sides of said piston to swing the first-named cylinder first in one direction and then in the other at a uniform velocity, means actuated by the relative movement between said second piston and said second cylinder for reversing said oscillating means, and means adjustable to control the stroke of said oscillating means. 5. A lens surfacing machine comprising a tool support,

a work support, means for securing an abrading tool to said tool support, means for securing a workpiece to said work support, means for constantly urging one of said supports toward the other to hold the tool and workpiece in operative engagement under pressure, means for adjusting said one support angularly relative to the other support so that the pressure is applied normal to the operating surface of the tool, means for rotating one of said supports, and hydraulically-actuated means including a cylinder and a piston reciprocable therein for oscillating one of said supports simultaneously with said rotary movement about an axis parallel to the direction of application of pressure.

6. A lens surfacing machine comprising a base, a tool support journaled in said base, a work support mounted on said base for rectilinear reciprocating movement, means for securing an abrading tool to said tool support, means for securing a workpiece to said work support, means for constantly urging said work support toward said tool support to hold the tool and workpiece in operative engagement under pressure, means for adjustingsaid work support angularly so that the pressure is applied in a direction normal to the operating surface of the tool, means for rotating the tool support, and hydraulically-actuated means including a cylinder and a piston reciprocable therein for simultaneously oscillating said work support about an axis parallel to the axis of applied pressure.

7. A lens surfacing machine comprising a base, a tool spindle mounted on said base to rotate on a vertical axis, means for securing a lapping tool to the upper end of said spindle, a column adjustable rectilinearly on said base in a horizontal direction, a bracket mounted on said column for angular adjustment about a horizontal axis extending at right angles to the direction of adjustment of said column, a carrier mounted on said bracket for oscillation about an axis extending at right angles to the axis of adjustment of said bracket, a cylinder secured to said carrier, a piston reciprocable in said cylinder in a direction parallel to the axis of oscillation of said carrier, a piston rod secured to said piston to project through the lower end of said cylinder, means for securing a lens to the lower end of said piston rod, means for applying air pressure to the upper face of said piston to urge said lens into engagement with said tool under pressure, means for rotating said tool spindle, and means for simultaneously oscillating said carrier including a second cylinder, a second piston reciprocable therein, means for applying hydraulic pressure alternately to op posite sides of said second piston to effect swinging movement of the lens over the operating surface of the tool alternately in opposite directions at a uniform velocity and to effect practically instantaneous reversal of said swinging movement at opposite ends of the swinging stroke, and means actuated by the relative movement between said second piston and said second cylinder for reversing said oscillating means at opposite ends of the stroke of said second piston in said second cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,659,277 Maynard Feb. 14, 1928 2,286,361 Goddu June 16, 1942 2,381,449 Holman Aug. 7, 1945 2,643,492 Burroughs June 30, 1953 2,649,667 Cooke Aug. 25, 1953 2,880,555 Brueckner et a1. Apr. 7, 1959 FOREIGN PATENTS 977,720 France Nov. 15 1950