US1230530A - Lens grinding and polishing machine. - Google Patents

Description

E. STEAD.

LENS GRINDING AND POLISHING MACHINE.

APPLICATION FILED JUNE II I9I5.

1,230,530. Patented June 19, 1917.

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APPLICATJQN FILED JUNE 1; I915- Patented June 19, 1917.

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UNITED STATES PATENT OFFICE.

ERNEST STEAD, OF BINGHAETON, YORK.

, LENS GRINDING AND POLISHIN G MACHINE.

Specification of Letters Patent. Patented June 19, 1917.

Application filed June 1, 1915. Serial No. 31,538.

To all whom it may concern:

Be it known that I, ERNEST STEAD, a citi zen of the United States of America, and resident of Bin hamton, in the county of Broome, in the tate of New York, have vented new and useful Improvements in Lens Grindin and Polishing Machines, of

ished under a combined rotary and planetary action of the ments.

Another object is to enable the machine to be easily and quickly adjusted for grinding grinding or polishing elethe surfaces of different forms of lenses without affecting the speed ratios or direction of movement of the rotary or planetary motions.

A further object is to provide simple means for slightly shifting one of the grinding or polishing elements relatively to the other to prevent the recurrence of contact at any one point between the work and tool in order to reduce to a minimum the liability of producing channels or line marks in the lens.-

Other objects and uses relating to specific parts of the machine will be brought out in the following description.

In the drawings Figure 1 is a front elevation of a lensgrinding and polishing machine embodying the various features of my invention.

Fig. 2 is an enlarged vertical sectional piew of the same machine taken on line 2-2,

Fig. 3 is an enlarged horizontal sectional view taken on line 3'-3, Fig. 1.

Fig. 4 is a vertical sectional view taken in the plane of line H, Fig. 3.

Fig. 5 is a vertical sectional view through the gear case under the table, taken in the plane of line 55, Fig. 2, and showing a portion of the motor shaft and its clutch connection with the gear shaft.

Fig. 6 is a top plan of the electric switch 'for controlling the operation of the motor and adjacent portion of its operating mechanism.

Fi 7 is a vertical sectional View taken on line 5-7, Fig. 6. Fig. 8 is a diagrammatic plan of the rotary grinding or polishing tool and rotary lens holder showing their relative directions of movement.

As illustrated, the machine comprises a main frame -l adapted to rest upon the floor and having a substantially horizontal bed or table 2 for supportin the various mechanism at the desired heig t for convenience of operation and inspection of the various mechanisms and work, the table or bed 2 being provided with a circular vertical opening 3 therethrough for receiving certain portions of the driving mechanisms for the tool and work and also provided with a raised annular flange 4 surrounding the opening and concentric therewith, but some distance therefrom for retaining any loose tools or Work which may be temporarily supported upon the bed against accidental displacement.

Secured to the lower and upper faces of the bed or table '2, co-axial with the opening 3, are gear case sections -5- and 6 having suitable bearings 7 and 8 centrally in their adjacent ends for receiving and supporting the adjacent portion of a vertical shaft 9, the lower end of the case section 5 and the upper end of the case section 6 being closed by caps 10- and ,11, respectively, for excluding dust and other foreign matter from the working parts Within the case.

The lower end of the shaft 9- is journaled in a bearing 12 in the bottom .of the cap 10 and is provided with an anti-friction end thrust bearing 13-, shown more clearly in Figs. 2 and 5, the intermediate portion of said shaft being connected by beveled gears --14 to B. horizontal shaft section l5 which in turn is connected by a clutch or coupling 16 to a co-axial armature shaft -17 of an electric motor 18, the latter being secured in a horizontal. position to the under side of trio switch -l9- of any suitable construction capable of controlling the operation of the motor, and preferably of a snap-switch type having an operating member or handle by which the rotary part thereof may be operated. I

It is preferable, however, to provide means whereby it may be operated by the foot, and for this purpose the rotary shaft to which the handle is attached is provided with a ratchet wheel -21 adapted to be engaged by a pawl 22 on a co-axial rock arm -23- which is loose on the switch shaftand is connected by a link -2 l to one arm of a bell crank lever 25 on the under side of the bed or table -2-, as shown more clearly in Figs. 1, 6 and 7, the other arm being attached to a vertical operating rod 26- extending to a point near the floor line and provided with a pedal ;-27, whereby the rod may be depressed by the foot of the operator.

The rod -26 is guided in bearings 28- on one of the supporting legs of the table 2 and is retracted by a coil spring 29 surrounding the upper end of the rod between the uppermost bearing 28- and a shoulder 30 on the rod, as shown in Fig.1, the spring serving not only to 301 retract the rod 26, but also to return the rock arm 23- and pawl 22- to their starting positions to engage the next adjacent tooth of the ratchet wheel --21.

The binding post as -31 of the switch may be connected by wires -32 to any available source of current supply capable of operating the motor.

In order that the tool holder as 33 carrying the grinding tool or lap as a eegmay be driven at the desired speed, it is secured by a set screw 34- to the upper end of a shaft extension 5 co-axial with but separate from the shaft 5 and connected to said shaft by suitable gearing presently described.

The upper end of the shaft 5 is tapered and tightly fitted in a corresponding socket of a sleeve 35, telescoping within another sleeve -36 on the lower end of the shaft section 5 so that the two shafts may be rotated relatively to each other at the same or different speeds, the sleeves and shaft sections 5 and 5 being held exactly co-axial and against relative endwise movement by anti-friction end thrust bearings '37-.

The lower end of the sleeve 5 is provided with a pinion 38 meshing with a relatively larger gear 39 on an upright countershaft l0 which is journaled in suitable bearings in the bottom and top of the case 6- and is provided with a pinion 41- meshing with a relatively larger gear 42- on the lower end of the sleeve -36 thus completing the gear train for naaonao transmitting rotary motion from the shaft -5-- to the co-axial shaft section -5' carrying the tool holder 33 andcausing the tool holder to be rotated at a lower rate of speed than that of the motor, the gear -14 on the shaft 5- being also relatively larger than that on the motor shaft extension -15.

The shaft 5'- is not only journaled at its lower end upon the sleeve -35-, but is also journaled intermediate its ends in a bearing -43 on the cap 11 close to the tool holder 33 which serves to maintain an exact co-axial relation between the tool holder and its driving shaft 5-, and also reduces to a minimum the liability of vibration of the tool holder which might affect the accuracy of the grinding of the surface of the lens.

The lens as b is secured in the usual manner by paste or other adhesive to one of two relatively movable lens-holding sections -44 of any well-known construction, the other section being rigidly secured to a centering pin or spindle l5 on one of the sections as 46- of a flexible shaft r-l7 to move endwise therein, and together with the lens holder M is spring pressed toward the tool -w by a coil spring 48 acting upon the inner end of the centering pin or spindle which is keyed to the shaft section -et6 by a screw 49 to rotate therewith, the screw -49 being passed through a slot -50 in the adjacent side of the shaft section 46 to allow relative endwise movement of the parts 45 and 46, thus permitting the lens holder to be lifted from the grinding or polishing tool wagainst the action of the spring 48 to remove the section to which the lens is secured when desired for inspection or other purposes.

The upper end of the shaft section 46 is connected by a universal joint -51 to an upwardly extending shaft section --52 which is feathered or splined to an adjacent shaft section .53 to rotate therewith and allow the sections to be adjusted lengthwise of each other, the section 53 being connected by a universal joint 5% to a vertical shaft section 55.

This section 55- is journaled in the front end of a horizontal bracket -56 coaxial with the axis of movement of the tool holder 33- and is connected by gears 57-to a horizontal shaft -58 also journaled in hearings in the bracket 5( which is secured to an upright standard -59 rising from the rear side of the bed or table 2-.

The rear end of the upper horizontal shaft 58 is connected by beveled gears -60 to an upright shaft 61 which is journaled at its lower and upper ends in bearings 62- on the standard -59- and is connected at its lower end by beveled gears 63 to a forwardly extending horizontal shaft 64-.

This shaft -64' is journaled in suitable bearings 65- on a rearward extension 66 of the case 6 and is connected by beveled gears 67 to the sleeve 36 on the lower end of the shaft section 5 so that the tool holder and work holder are driven from the same source of power and, therefore, in synchronism, the gear connections between the shaft -5 and flexible shaft '47 being so arranged and proportioned as to drive the work holder in the same direction and at the same rate of speed as the tool holder.

Planetary motion.

In grinding or polishing cylindrical, spherical or toric surfaces of different degrees of curvature by means of a rotary tool, it is desirable to progressively shift the position of the lens relatively to the tool so as to avoid cutting circular lines or channels in the lens by regular recurrent rubbing contact between the same points of the lens and tool, and for this purpose, I have provided means for impartin ,a planetary motion to the lens holder relatively to the tool, but in an opposite direction, and at a different rate of speed, in this instance, one-fourth the speed of movement of 'the tool and lens holder about their respective axes so that when these parts are properly set at the beginning of the operation for grinding a torio lens, the corresponding axes of the diiferent curves of the tool and lens are always registered with each other on each quarter turn of the tool or lens holder.

These results are accomplished by deflecting and holding a portion of the flexible shaft -47 to one side of the axis of the tool holder and then rotating the deflected portion about said axis, the degree of deflection depending upon the degree of curvature of the grinding or polishing surface to bring the axis of the lens-supporting spindle 45 approximately radial to such surface, and for this purpose, the shaft sec: tion 46 carrying the lens supporting spindle 45 is journaled in a sleeve -68 passing through a slotted plate -69 and held against rotation by radial pivotal pins -70 in opposite sides of the plate and entering holes in opposite sides of the sleeve to allow the latter to adjust itself to different angles as the plate is adjusted in setting the flexible shaft section 46- at the desired angle, after which the sleeve is held in its adjusted position by a set screw -7l, Figs. 3 and 4.

The late 69 and portion of the flexible shaft passing therethrough are arranged within a relatively large horizontal gear -72 which is journaled in a suitable The rear end of the horizontal shaft 78 is connected to the upright shaft 61 by beveled gears '81-, thus synchronizing the rotation of the gear 72 and planetary movement of the lens holder with the rotary movement of the tool holder, the ratio of the gears 72- and 8l being four to one so that the lens holder will travel one-fourth of its 0 ole during each revolution of the tool hol er, thereby causing like' axes of the tool holder and lens to register each quarter revolution of those parts about their respective axes which is important, particularly in grinding toric' lenses.

In order to further reduce the liability of cutting objectionable grooves or channels in the lenses during the grinding or polishing operation, I have provided simple means for shifting the lens holder back and forth relatively to its orbit consisting, in this instance, of a pair of eccentrics 82 mounted upon a horizontal shaft 83 which is journaled in suitable bearings on the upright standard -59 and is driven from the upright shaft 6l by angle gears 8 1, said eccentricsbeing connected by pitmen 85- to opposite sides of the frame 74., as shown more clearly in Fig. 3, said frame being movable along and upon ways -86 on the front end of the bracket 7 When the slide 69 is adjusted to the desired position, it is held in such position by means .of a set screw 7 1, thereby causing the lens to travel in a circular orbit around and upon the face of the tool --a', it being understood that the gear 72 is co-axial with the axis ofthe tool holder 33 and mandrel 55 and that the degree ofadjustment of the slide 69 depends upon the curvature of the surface of the tool.

It is also evident that in grinding convex surfaces, the slide and lens holder will be at the same side of the axis of the tool holder, while in grinding concave lenses, the slide and lens holder will be at opposite sides of said axis without changing the speed or direction of planetary motion of the lens.

What I claim is:

1. In a lens grinding and polishing machine, a rotary work holder adjustable to different angles relatively-to the axis of the tool holder, means for locking the work holder in its adjusted position, a, rotary tool holder, and mechanism for rotating the work holder and tool holder in the same direction and at the same rate of speed.

2. In a lens grinding and polishing ma chine, a rotary tool holder and a rotary lens holder cooperating therewith, means for driving the tool holder and lens holder in the same direction and at the same rate of speed, additional means for moving the lens holder in an orbit about the axis of, but in an opposite direction to and at a different rate of speed than the tool holder, and cooperative means for reciprocating the lens holder relatively to its orbit and during its planetary motion.

3. In a machine for grinding and polishing lenses, co-axial rotary shaft sections, driving means for one of said sections, a tool holder carried by one of the sections to rotate therewith, 'means for driving the other section, means driven by the lastnamed section for driving the tool-carrying section at a different rate of speed, a lensholding section cooperating with the tool holder, means for moving the lens holder in an orbit about the axis of the tool holder, but in an opposite direction and at a different rate of speed, and additional means for rotating the lens holder in the same direction and at the same rate of speed as the tool holder.

4. In a lens grindingand polishing machine, a rotary tool holder and actuating means therefor, in combination with a mandrel co-axial with the tool holder, a flexible shaft connected to the mandrel, a lens holder on the flexible shaft, means for rotating the mandrel in the same direction and at the same rate of speed as the tool holder, and additional means for deflecting a portion of the flexible shaft to one side of said axis and rotating it in an orbit about the same, but at a less speed than that of the mandrel and tool holder.

5. In a lens grinding and polishing machine, in combination with a rotary tool holder and actuating means therefor, a revoluble member co-axial with the tool holder,

naeonac driving means for said member, a rotary shaft passing through said member and adjustable toward and from its axis, means for holding the portion of the shaft paming through the member in its adjusted position, a lens holder carried by the shaft to 00- operate with the tool holder, means for rotating the shaft, and additional means for ivleiziprocating said revoluble member radia y.

6. In a machine for grinding and polishing lenses, the combination of the grinding element, a rotary shaft carrying a work holder, means for adjusting, the work holder shaft to different angles relatively to the grinding element, and means for carrying said shaft at the adjusted angle in a planetary motion about the produced axis of the grinding element.

7. In a machine of the character described, the combination of a rotary tool holder and actuating means therefor, a flexible shaft having a work holder thereon, and means for deflecting a ortion of said shaft to one side of a direct ine between its ends and for rotating such deflected portion in an orbit about the produced axis of the tool holder.

8. In a machine of the character described, the combination of a tool holder and a cooperative work holder, shaft sections connected by a universal joint, the work holder being secured to one of said shaft sections, means for deflecting the shaft sections at the joint and for holding them at an angle to each other, and means for moving the joint in an orbit about the produced axis of the tool holder.

9. In a machine of the character described, the combination of a rotary tool holder and actuating means therefor, a work holder and a rotary driving element therefor adjustable to different angles relatively to the axis of the tool holder, and means for holding said element in its adjusted position and for moving it in an orbit about said axis.

In witness whereof I have hereunto set my hand this 24th day of May, 1915.

ERNEST STEAD, Witnesses:

THOMAS E. DILLON, CARL F. JoENsoN.

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