US1491383A - Lens-grinding apparatus - Google Patents

Description

Apr 22, 1924.v

G. s. DEY

LENS GRINDING APPARATUS Filed May 31. 1921 INVENTOR GILBERT S.DEY

BY 1, mum- H WM ATTORNEY Patented Apr. 22, 1924.

GILBERT S. DEY, OF SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOR T0 AMERICAN OPTI- OF MASSACHUSETTS.

LENS-GRINDING- APPARATUS.

Application filed May 31, 1921.

T 0 all whom it may concern.

Be it known that I, GILBERT S. Day, a citizen of the United States, residing at Southbridge, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Lens- Grinding Apparatus, of which the following is a specification.

This invention relates to improvements in lens-grinding apparatus and has particular reference to an improved type of tool for use in the surfacing of lenses.

One of the principal objects of the present invention is the provision of a novel and improved construction of tool especially adapted for use in the formation of multifocal lenses.-

A further object of the present invention is the provision of an improved tool which shall have a sharp outer edge or bounding line so that it can be worked up to an exact point without causing aberration at the particular point in question and which will satisfactorily conform to and properly abrade or polish the entire surface covered by the tool.

A further object of my invention is the provision of an improved form of tool and process of producing the tool so that the lubricating fluid employed in the grinding or polishing operation will properly work under and to the center of the tool and prevent overheating of the parts or injury to the work.

Other objects and advantages of my improvement should be readily apparent by reference to the following specification taken in connection with the accompanying drawings, and it will be understood that I may make any modifications in the specific features of construction disclosed within the scopeof the appended claims without departing from or exceeding the spirit of my invention.

Figure I represents a plan view of an apparatus making use of my improvement.

Figure II represents a sectional view as on the line IIII of Figure I.

Figure III represents an enlarged detailed section through the tool proper.

Figure IV represents a bottom view of the tool'shown in Figure III.

Figure V represents a bottom plan view of a slightly different form of tool.

Serial No. 473,784.

Figure VI illustrates the mation of and Figure VII represents a sectional view through another modified form of my tool.

In the drawings, the numeral 1 designates the main frame or base of a lens-grinding machine having rotatably mounted therein the spindle 2 of the lens holder 3 adapted to hold the lens blank at for rotary movement. Carried by the frame may be a' suitable bracket or support 5 for the arm 6 carrying the upper spindle 7 rotatable as by power suitably applied to the pulley Sand bearing my improved grinding tool which may be either loosely mounted for driving movement on the end of the spindle or may be positively driven by the spindle as preferred.

My improved tool, in the form illustrated in Figures III and IV, comprises the base portion9 having the socket 10 to receive the spindle 7 and having suitably formed or secured thereon the outer annular grinding member 11 which may be formed from fibre, hard pitch, or other relatively stiff and un yielding polishingmaterial. This member 11 is in the form of a wall, preferably in the shape of a truncated cone, and encloses the central polishing material 12 which fills process of forthe tool illustrated in Figure V,

the entire interior of the member 11. This latter may be either a soft pitch composition as shown in Figure III or may be of felt or of cheese cloth, scrim. or other suitably reticulated material. Figure V shows a bottom plan view of a polisher having the effect of the use of reticulated material but in which the soft pitch center or the like is employed.

The process of-formation of this particular tool is illustrated in Figure VI in which it will be seen that there is a base mold section 13 into which fits the base block 9 and annular portion 11 which have preferably first been formed in another suitable mold. The parts having been put in this position, the center of the member 11. is then filled with the polishing material 12 and the plunger 14 brought down against said material. Said member 14 has its lower face formed to the curve which it is desired to reproduce on the face of the tool and is preferably heated. It is also provided with the wire screen or mesh portion 15 held as by the lateral fastening members 16, the-heat acting on these to have them insufficiently warm condition to soften the materials 11 and 12. Therefore, as the plunger" is brought down it will press the parts 11 and 12 to conform to the shape of thealower face of the plunger forming in the member 11 the groovesi17 which receive the securing member 16 and forming on the central softened portion the reticulated surface 18.

A tool of this type when properly formed may be used for polishing with extremely satisfactory results in that as the fluid is applied to the surface of the lens and'the tool and lens rotated in the usual manner, the lubricating fluid will work under the hard plunger 11 and particularlyin through the passages formed by the groove IT and will spread to the center of the tool to keep it properly lubricated as through the grooves or passages formed by the reticulation of the surface.

This structure is particularly desirable since in the polishing of lenses with a solid polisher care has always had to be observed that the center of the tool was kept properly lubricated as it otherwise has a tendency, particularly in the case of a pitch polisher or the like, to become dry when it will heat and be pulled somewhat out of shape through the friction with the lens destroying the efliciency of the polisher. This is particularly noticeable when a slight projection or the like is formed on the polisher which will glaze over and then delay the polishing actilgn, cause burned effects on the glass or the li e.

It will be noted that my improved polisher is especially adapted for use on bifocal lenses in which it is desired to polish the lens exactly up to a given line which may be either a cliff or ridge or a merged line of joinder between the surfaces. In any event, it is essential that the polisher be sufiiciently stifi and rigid to hold its form exactly up to the edge to form a sharp line and without rubbing over the edge causing aberrations. At the same time it is desirable that the tool be centrally properly lubricated to ensure proper polishing action and that it be of such shape that it will have a tendency to conform to the shape of the lens to be polished during the polishing operation and ordinarily without materially altering the shape or curve which has already been generated. on this surface. A continuous hard polisher cannot be as satisfactorily employed for these purposes due to its tendency to maintain its own shape rather than to conform to the lens, while a soft polisher is deficient in that it will not preserve the necessary sharp dividing line. I have found, however, that by my improved combination extremely satisfactory results can be obtained, the thickness of the member 11 being such that it will hold the edge, will satismenses factorily polish out the edge but will wear down substantially equally with the central portion so that the entire tool is at all times in proper polishing engagement with the glass, its outer edge is positively maintained, there is produced a satisfactory and correct line of division between the fields of the lens, the center portion being soft enough to conform somewhat to the shape of the lens, and there is secured the necessary rapid polishingaction to produce quickly the desired lens. 7 7

It will he understood that while I consider as most desirable the combination of hard and soft pitches or the like the form shown in Figure V, various modifications may be made and I may, if desired, obtain the same reticulated effect or the like by the use of a suitable fabric material disposed in layers as at 19 in the interior of the wall 11 as specifically illustrated in Figure VII.

I would also call particular attention to the truncated cone shape of my improved tool. This has a particular advantage in that with this shape of outer wall it is possible to work up exactly to the edge or cliff of the lens and to polish properly the surface without any liability of the tools first striking the overhang or upper edge of the clilf or any liability of the tools coming into contact with and pitching this edge while allowing the free sidewise movement up toward the edge. In this way I am able in connection with a depressed bifocal to polish perfectly the entire surface without interfering with the edge or line of joinder which may be left gray and unpolished if desired or may be specially polished. Also, this cone effect makes it easier as the tool wears down to maintain a sharp edge rather than to have a rounding over edge as is more likely to occur with right angle corner.

I claim: 1

1. A lens polishing tool. of the character described, comprising an outer surface formed from a. hard pitch composition, said surface being in the form of an annular wall, and a softer polishing material enclosed within said wall.

2. A lens polishing tool of the character described. comprising an outer annular wall formed from relatively hard composition, and an enclosed portion formed from a soft pitch composition.

3. A lens grinding member comprising an outer enclosing wall formed from a hard pitch composition material, and an inner portion formed from soft pitch composition material, the outer hard pitch member having a plurality of grooves at its operative surface communicating with said inner soft pitch composition material.

4;. A lens polishing tool of the character described, comprising a relatively hard frustro-conical outer surface formed from a hard pitch composition material, and a soft pitch composition material enclosed within said outer surface, the lower faces of said hard and soft pitch composition materials being of arcuate configuration.

5. A lens polishing member of the character described, comprising an outer relatively hard composition enclosing wall formed from a hard pitch composition material, and an inner reticulated polishing portion formed from a soft pitch composition material.

6. A lens polishing tool of the character described, comprising a relatively hard composition outer surface formed from a hard pitch composition material and having a frustro-conical shape, said surface being in the form of an annular wall and an inner portion of softer material formed from a soft pitch composition material, said outer member having a plurality of grooves at its operative surface communicating with said inner softer material, the operative surfaces of said inner and outer portions being of arcuate configuration, and criss-cross grooves formed on the opposite surface of said inner portion.

In testimony whereof I have aflixed my signature, in presence of two witnesses.

GILBERT S. DEY.

Witnesses:

Susan OASAZZA, ALICE G. HASKELL.

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