US1416947A - Lens-forming process - Google Patents

Description

G. S. DEY.

LENS FORMING PROCESS.

APPucAnou FILED IAN-3, 1920.

o I I INVENTOR GILBERT S. DEY,

Z3 ATTORNEY$ UNITED STATES PATENT WEN-13E? GILBERT S. -DEY, OF SOUTHBR IDGE, MASSACHUSETTS, KSSIGHOB TO AMERICAN OPTICAL COMPANY, OF SOUTL-IBRIDGE, MASSACHUSETTS, A QOBi-PORATIOLPQF MASSACHUSETTS.

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Specification of Letters Patent. Patented i 1922 Application filed January 3, 1920. Serial No. 349,292. l i Y 1 T 0 all whom it may concern:

Be it known that I, GILBEBBSgDEY, a citizen of the United States, residing-,at-Southbridge, in the countyof Worcester and State of Massachusetts, haveinvented certain new and useful Improvements in LensTForming Processes, of which the following isaspecification.

This invention relates to new, land improved processes of forming ophthalmic lenses and hasparticular reference to lenses of the toric type as being the more difficult to constructat the :present time, althoughit will be understood that it is-equallyapplh cable to spherical, ,bifocaliand -,.other forms of lensblanks. -z One of the leading objects of: thepresent invention is the gprovision -ot, a novel ,and improved process through tl1e]i1se';of which the v lensmay be satisfactorily :droppechto the correctshape without the injurious. effects on the surface caused by moulding of thelens in this form, and consequently a process which will serve to reduce-the grinding of the ,torio or other ldifiicult to produce surfaces to a minimum. rAnother object of the invention is the provision of a novel and improved-process; for forming blanks of this character in which the axis of thecylinder, in the case ofa cylinder or. toric blank, will be clearly, exactly and indelibly marked oradenotedso that the lens may :be' subsequently readily finished and the intended cylinder axis--maintained, thus both increasing the speed of production and lessening the costot production .of the lens of the type in question; Other obj ects and. advantages of my consti'uction should be readily-apparent by-u-eterence: to the a following specification taken :in connection: with-the accompa-nying drawingsgand it 'willbe understoodthat' I-may make any modifications .in the specific'details of construction shown and described within the scope of theappended claims without departing-fromor exceeding the spirit of mylinvention.

' Figure I represents a plan viewof one of the mould -members or supports, showing certain glass-pieces in-position thereon. 1 Figure 11 represents a transverse sectional view as on the lineII- IIof Figure I, show inga lens in its initial position EigureIII representsa longitudinal sectional-v-ieW-on the Iinei 'III- III.

Figure P v represents a sectional view of the lens at one step inmy process.

Figure V represents a' plan ,view; thereof atafurther step in the process. 4 1 Figure I-represents. a sectionalrview of the construction shown in' Figure V.

"Figure presents "sectionalview ofa subsequent step intheiarocess.

Figure VIII represents a sectionah-viewoi a difl erent form of mould member."

Prior to my present inventionatheim'o'st comi on way of producing What-isknown astor'c or like lenses having twopowers in the opposite meridian has been by the grinding ofordiuary glass blanks ivliich'have been pressed in moulds to secure a certain general curvature, the toric; surface being ordinarily roughed out in some suitable mannerto pro- .duce a closer approximation to the toric curve,'a-nd then -beinggiven suit-able relative motion over atool bearing the ourveswhich it is'desired to transfer.contragenerically .to theglass. i, [The purpose of my invention, however; is

.to do laway zto the: largest possible degree with this preliminary work and to reduce to minimum the necessary grinding i on the toric face of the lens, in lthat-certain difficulties' are inherent in. grinding tonic-surfaces not 'met with in plain surfaces. In the accomplishment of this resulti I first preferably polish on both sidesitheglass blank l', after which I mount it upon a'suitable-formen-2, .which may be acarborundum or other slab suitably surfaced and provided with the necessary curve "or curves accordinguto the particular curves which the final lens is desired to have. Inasmuch. as'the toxic-surface is the one which is primarily consideredgjancl as. my process is particularly applicable in the factory production of what is known as toric blanks, that is, blanks with the toric side finished, the spherical side remaining to be ground, I prefer to make use of such form of mould 01' 'foi'mer2, as will not'come into contact with what is to'be thc final toric surface but only come in contact-with the opposite surface of the glass blank. Ordinarily the toric curve is placed on the inner face of the glass and in these cases I- findit particularly advantageous to make use of concave mould or former faces 3 on the member 2, which in this case are not of the curve or curves to be produced on the torio face'of the glass but are, so calculated that if a flat piece of glass be placed on the former and caused by heat to drop down to fit the former, the curves resultant from the shape of the mouldand the thickness of the glass together produced upon the upper or noncontacting face of the blank will be substan tially the curves desired.

The production of the exact curves can, of course, be accomplished by dropping, the blank over a convex form member a, such as is illustrated in connection with Figure VIII, the disadvantage of this form, however, being that it is necessary to employ the side members 5 with the adjusting screw 6 carefully set to maintain the blank in exact correct position againstany lateral slipping movement, while in the case of Figures I and II of the drawings the side members 5 and adjusting devices 6 are shown and may be employed for ordinary conditions but this is not entirely necessary since the concave former will of itself serve to steady and prevent undue lateral or longitudinal sliding movement on the glass. In any event, the glass blank, as before stated. preferably of polished condition, being placed on the former, the former and blank are subjected to heat to soften the glass so the glass will drop down to and at its contacting surface assume the shape of the former, although as before mentioned the former may be so calculated as with the glass thickness added to produce any desired curve or curves on the upper face of the glass if that is the face which is to be subsequently first finished. i

It will be understood that it is of extreme importance that the cylinder axis be maintained during the subsequent grinding or polishing operations as if the tool and lens are not placed for these operations in exact correct relationship then the advantage gained by the first steps in my process will be lost and initial. amounts of glass will have to be removed. To, therefore, insure correct subsequent operations I preferably place on one face of the glass 1. the axis mlesig: nations 7 coinciding with the axis of the former 2, and if desired the numerals S designating the dioptric values of the curves which are to be produced on this face of the glass my moulding. For this puropse I'use a fusible enamel which may be quickly and easily applied before heating the glass, and which as the glass is heated will maintain its regular form but will be fused into the glass and become united therewith as an integral part thereof. thus continuing to designate the axis of the glass until the fusibleenamel has been entirely ground away or removed. After the dropping' and line fusing operation has been completed the glass is then taken to a grinding tool where the term surface 9 may be ground and polished, or merely polished, as the necessity may be, when the blank may be sold in this form with the surface 10 still in roughened condition from contact with the mould if desired, or the surface 10, if this be the toric one, which has been in contact with the mould, be ground and polished when the semi-finished blank, it is termed in the trade, will be found to be substantially transparent and capable of ready-examinw tion for the determination of interior defects before the final curve is placed on the opposite side thereof.

I claim:

' 1. As an article of manufacture, a dropped toric ophthalmic lens blank having axis designations fused thereon by the heat of the dropping operation. f

2. The process of forming a toric 'lens consisting in shaping a form with a toric surface, placing the glass material on the form, placing fusible axis designations'on the glass, and subjecting the parts to heat .to cause the glass to assume toric form and the fusible designations to unite with the glass and permanently indicate the cylinder axis which has been produced on the glass by the dropping process." Y

3. The process of forming a toric lens :blank consisting in constructing'a form, ealcul ting the curves on the form to allow for pre etermined glass thickness, grinding the glass tdthe predetermined thickness while in piano form, placing the glass thus ground on the torie form, and droppingthe glass to produce on the free surface the calculated curve. 1 r 1. i 4. The process of forming "a toric lens blank consisting in constructing a form, calculating thec urves' on the-form to allow for predetermined glass thickness, grinding the glass to the predetermined thickness while in plane form, placing the glass thus ground on the toric form, marking suitable designations on the exposed face of the glass, and dropping the glass on the form to produce the predetermined surface; 5. The process of forming a toric lens blank consisting in constructing alform, calculating the curves on the form to allow for predetermined .glassthickness, grinding. the glass to the predetermined thickness while in plane form, placing the glass thus ground on the to'ric-form, marking suitable designations on the exposed face-of the glass, droppingrthe glass on the form to produce the predetermined surface, and subsequently grinding and polishing the surface injured by the dropping process.

6. The process of dropping glassblanks, consistingin. preparing a form with a plurality of glass receiving recesses, polishing glass in plane form, placing the piano glass in sections above the several recesses, placing suitable designations-of fusible material on the blanks,'and subjecting the parts to heat to cause the glass to drop down to and assume the curve of the form and the designations to permai'ientiy unite with the glass, and subsequently grinding the glass on the form engaging side to restore its curve and finishing the glass on the opposite surface in accordance with the designations appearing thereon.

7. The process of dropping glass blanks, consisting in preparing a form with a plurality of glass receiving recesses, polishing glass in planoform, placing the plane glass in sections above the several recesses, placing suitable designations of fusible material on the blanks, and subjecting the parts to hcato cause the glass to drop down to and assume the curve of the form and the designations to permanently unite with the glass, subsequently grinding the glass on the form engaging side to restore its curve, finishing the glass on the opposite surface in accordance with the designations appearing thereon, and eontinuin this finishing operation until the designations are obliterated from the field of vision of the lens.

8. The process of forming ophthalmic lenses, including shaping a form with predetermined curves, providing side members for the form to prevent lateral slipping of the glass, mounting the glass upon the form between the side members, and subjecting the parts to heat to cause the glass to settle heat when properly positioned to produce a predetermined blank.

10. As an article of manufacture a dropped cylinder lens blank having axis designations thereon of a fusible cement, said axis designations being permanently united with the glass by the action of the heat required for dropping the blank to cylinder form.

'11. As an article of manufacture a cylinder lens blank having axis designations fusec ,011 the cylinder face thereof.

In testimony whereof L have aflixed my signatnre, in presence of two witnesses.

, GILBERT S. DEY;

XVitnesses:- I i H. K. PARSONS, v ALICE G. HA-sKELL.

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