US1441805A

US1441805A - Lens-grinding machine

Info

Publication number: US1441805A
Application number: US390692A
Authority: US
Inventors: Harry W Hill
Original assignee: American Optical Corp
Current assignee: American Optical Corp
Priority date: 1920-06-22
Filing date: 1920-06-22
Publication date: 1923-01-09
Anticipated expiration: 1940-01-09

Description

m mmw.

Jan. 9, 1923,

H. W. HILL.

LENS GRINDING MACHINE.

FlLED JUNE 22,'1920. Z SHEETSSHEET 1.

' INVENTOR I HHWRV WH/u.

Jan. 9, 19230 I l/MHLSIIIS.

H. W. HILL. LENS GRINDING MACHINE.

FILED JUNE 22, 1920. 2 SHEETSSHEET 2.

IINVENTOR HRRRYW HILL BY i II MI I N M:

lEY-S til Fatented mlan; 9, lhfld tlltltil lHm HARRY W. HILL, F SOUJEHFREDGJE, MASSACHUSETTS, fltSfillGNOltt T0 AMERICAN QF'IICAL COMPANY, U15 SOUTHBRIEDGE, MASSACHUSETTS, A VOLUNTARY ASSQ- "CIATION 0F MASSAGHUSJETTS.

tnn's-enrnnrive MAGHINE.

Application filed June 22,

To all whom it may concern:

Be it known that l, HARRY W. HILL, a citizen of the United States, residing at Southbridge, in the county of Worcester and State of Massachusetts, have inventedcertain new and useful Improvements in Lens-Grinding Machines, of which the following is a specification.

This invention relates to improvements in grinding machines and has particular reference to a machine especially adapted for use in the manufacture of ophthalmic lenses. 1

@ne of the leading objects of the present invention is the provision of a novel and improved construction of machine which shall be substantially automatic in operation and which may be accurately set to produce the particular results intended, as to produce a given curve on a blank which at the completion of the grinding operation shall be of a predetermined thickness, and in which the application of abrasive during the grinding operation, the stopping of the grinding operation, and the like, shall be automatically effected.

Uther objects of the invention include a simplification and improvement in the structural details of machines of this general character, such as should be readily apparent by reference to the following speci-- fication taken in connection with the accompanying drawings, and it will be understood that l[ may make any modifications in the specific details of construction shown and described within the scope of the appended claims without departing from or exceeding the spirit of the invention.

Figure it represents a front elevation of amachine embodying the principles of this invention.

Figure Ill represents a side elevation thereof.

Figure lllfll represents a plan view.

Figure IV represents a detail of the block adjusting gauge. I

In the drawings, the numeral 1 designates the main table or base portion having journaled therein the spindle 2 adapted to carry thelens grinding or engaging member, 3, which may be of any desired form, in the present instance having been shown as of convex form, having the integral abrasive receiving flange rim t and having 1920. serial no. aedeea the groove or channed 5 formed in its face as well asthe central relieved portion 6. it would here call particular attention to the fact that the walls of the channel 5 are shown as vertically disposed or parallel to I the axis of the spindle 2 rather than radial to the curve, the particular reason for this construction being that the groove may at all times occupy the same position relative to the other portions of the machine irrespective of the wearingaway of the surface of the member 3, in that the member may be vertically adjusted to compensate for the wear and the position of the walls of the groove will thus hold the channel in constant relation as adjustment is made. This adjustment may be made as by the pair of lock nuts 7 threaded on the upper end of the spindle 2, a keyed washer 8 being interposed between the lock nuts and the bearing 9 on the spindle 2 to prevent accidental loosening of the parts during rotation.

In the form of invention illustrated there is located rearwardly of the spindle 2 a raised boss 10, and preferably forwardly thereof a second table portion 11. The machine may be constructed either of yoke formation having supports resting on both the tables 10 and 11, or of bracket formation, having support only upon one of the tables, as preferred. As shown in Figure H there is secured to the table portion 1 a base bracket 12 bearing the trunnion 13 on which is swingingly mounted the bracket 14 having the bearings 15 which support the spindle 16. This spindle has mounted thereon the sleeve 17 held against rotation in the bracket 15 and provided with a rack portion 18 engaged by the pinion 19 which has attached thereto the arm 20 bearing a weight 21 which when swung in one direction serves to raise and hold the spindle in elevated position and when swung in the opposite direction serves to force the spindle downwardly. The lower end of the sleeve 17 bears against the thrust bearing 22 on the spindle. To cause rotation of the spindle there is mounted on the upper bearing 15 the drive pulley 23 having suitable driving connection with the spindle 16, while secured on the spindle above said pulley is the collar 24 adjustably held in position as by the set screw 25 and bearing the adjustable stop 26 adapted to contact with the upper face of the pulley to limit the downward movement of the spindle. A lock nut 27 having an operating handle 28 may be mounted on the adjustable stop to secure it in desired position.

There is suitable driving connection between the pulley 23 and the spindle 16. One suitable form of such connection is illustrated in Figure I, in which the pulley has rising therefrom the pin 29 adapted to contact with a horizontally disposed pin or arm 30 on the collar 24 so that when the spindle is in depressed position the two pins or arms will interlock and cause the spindle to be driven, while when the spindle is raised elevation of the collar will move the

pins

29 and 30 out of engagement to automatically stop rotation of the spindle. The mechanism illustrated in Figure I is particularly adapted for use in the grinding of bifocal lens blanks or the like in which it is desired -to leave a central portion of the glass temporarily unabraded, the blank spinning about the groove 5 as a center so that this portion of the blank 31 will be unground while the surrounding portion striking the tool at the sides of the groove will be ground. For most efficient operation of the machine in this manner it is preferred that the lens be substantially rigidly held upon the spindle 16, while if the same be rigidly held it is necessary in order that the curve be reproduced from the lap that the spindle be radial to the lap and to suitably adjust the bracket 14 on its trunnion 13 there may be employed the adjusting screw 32 carried by the bracket 14 and engaging the boss 10,

- a vernier 33 serving to indicate the angular adjustment if desired. vVhen the parts have been properly adjusted the machine may be operated if desired without the use of the stop merely by inspection of an operator from time to time, or the machine may be set with the stop to operate automatically.

To supply abrasive to the lenses 31 during the grinding operation they may be either manually fed or automatically, as by the scrapers 38 riding in the abrasive groove 39 within the rim 4:,these scrapers being carried as by a cross arm 4C0 extending from the table portion 10 to the table portion 11 intermediate the pair of bracket arms 14. This cross arm may also be employed to receive the tool height gauge. It is to be understood in connection with the use of a tool such as shown in Figure I for example, that if the machine is to be set at different angles for different tools, in order to maintain the center of the spindle alined with the center of the surface interrupted by the groove 5, it is necessary that said surface be on line with the axis about which the bracket 14 swings. While a tool will not wear appreciabiy during the grinding of several lenses to an extent requiring any compensating ad- L la-1,806

justment, eventually the tool will wear off slightly so it is desirable to re-adjust it vortically, this being accomplished as previously mentioned through the use of the lock nuts 7 on the spindle To facilitate a determination of the amount of adjustment required, to enable the operator at all times to determine whether or not the tool is properly adjusted, and to assist in its vertical calibration, there may be secured to the bar 40 the plate 41, hearing the guide 4-2 for the slide plunger 43, having pivoted to its lower end a shoe 44 adapted to span the central recess 6 of the tool surface and rest thereagainst. The plunger 4:3 has its upper end adapted to contact with the arm 49 of the pointer 4:5 intermcdiately pivoted to the bracket 46 on the member 4-2 and riding over the indicator segment at? carried by said member 42. This device is calibrated for the particular curve of tool bcin f employed and measures accurately the height of the tool with respect to the fulcrum point or axis about which the bracket 1.4 turns, indicating any variation of the tool from the correct height and indicating when it has been properly adjusted. This device may either be left permanently in place on the arm 40 or may be temporarily applied, as preferred. If permanently in place means such as a latch a8 is preferably used to hold it in temporarily elevated position to prevent undue grinding away of the shoe e l; through constant contact with the tool 3.

Particular attention is called to the formation of the central recess 6 in the surface of the grinding tool, this recess being of size that the blank 31 being opcraicdupon will just overlap the edge of the recess inwardly. The purpose of this recess is to permit of equal wear of the tool, since were the tool solid at the center and the lens blank not overlapping the center the upper portion of the tool would be worn down more rapidly than the center of the tool, making it more difiicult to gauge and adjust the center of the tool, and also causing more or less of a bump bevelling off the edge of the lens being ground. lrVit-h the tool constructed as shown, however, the wear should be substantially uniform and no protuberance left at the center of the tool.

I claim:

1. In a machine of the character described, the combination with a table, of: a spindle rotatable therein, a lens grinding member carried by the spindle and having an annular groove, the walls of said groove being parallel to the axis of the spindle, an arm carried by the table and overhanging the spindle in spaced relation thereto, a contact indicator carried by the arm for engagement with the lens grinding member. and means for axially adjusting the spindle to shift the lens grinding member into cormenace rect operative position as denoted by the indicator.

2. A. machine of the character described, including a base portion, a spindle centrally journaled therein, trunnions carried by the base portion and equally spaced from the spindle, and a yoke member pivotally mounted on the trunnions, said yoke memher being centrally provided With spindle receiving bearings, a spindle contained within the bearings for cooperation With the spindle of the base, means for angularly adjusting the yoke to vary the relationships of the spindles, said adjusting means ineluding a lateral projection carried by the yoke, a threaded adjusting device carried by the projection and engaging" the base for rocking the yoke on its trunnions, means for adjusting the centrally journaled spindle axially, and means for indicating said adjustment.

3. A machine of the character described, including a base portion, a spindle centrally journaled therein, trunnions carried by the base portion and equally spaced from the spindle, a yoke member pivotally mountedof the base, a sleeve on each of the second mentioned spindles, a rack on the sleeves, a movable arm carried by the yokes, a pinion actuated by movement of the arm contacting with the rack for actually moving said spindles, and means for angularly adjusting the yoke to vary the relationships of the spindles, said adjusting means including a lateral projection carried by the yoke, and a threaded adjusting device carried by the projection and engaging the base for rotating the yoke on its trunnion.

In testimony whereof l have aihxed my signature, in presence of two Witnesses.

HARRY Wl-lllili. lWitnesses:

Anion G. Hasirnnn, Esrnnn M. LArLEn. V