US1085871A - Apparatus for making bifocal lenses. - Google Patents

Description

H. E. MENDELSSOHN. APPARATUS FOR MAKING BIPOGAL LENSES.

Patented Feb. 3, 1914.

APPLICATION FILED JAN. 29, 1913.

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APARATUS FOR MAKING BIFOCAL'LENEiES.

bpecification of Letters Patent.

Patented Feb. 3, 3914.

Application filed January 29, 1913. Serial No. 744,855.

To all whom it may concern Be it known that I, HERMAN E. MEN- nn'LssoHN, a citizen of Great Britain, residing at New York city, county and State of New York, have invented a new and Improved Apparatus for Making Bifocal Lenses, of which the following is a specification.

During the iminufacture of bifocallenses, a smaller glass .disk is superposed upon a larger disk and fused thereto in a mui'lle. During the fusing operation, means should be provided for permitting the free escape of the heated air from the space between the disks, so as to prevent the formation of objectionable bubbles.

My invention contemplates novel and ctlicient means for so spacing the disks that a free escape of the air can take place, the spacing means being so constituted as to securely clamp the low disk in position without regard to the thickness of such disk, and lo be freely accessible to the hand.

In the accompanying drawing: Figure 1 is a plan of an apparatus embodying my invention, showing the two glass disks in position; Fig. 2 is a longitudinal section of the apparatus without the disks; Figs. 3, 4, 5 and 6 are side views partly in section showing the position of the parts during (.OHSCKIF tire stages of manufacture, and Fig. 7 a section through the finished bifocal lens.

The apparatus comprises essentially a base plate 10 from which extends upwardly a fixed screw stem 11. This stem is shown to be secured to'plate 10 by means of an upper flange 12, and a lowercountersunk nut 13, engaging opposite sides of the Upon stem 11, there is free to travel a barrel 14- having an axial bore which is tapped to engage the thread of the stem. Barrel t my be made of cylindrical form and is ided with a lower circumferentialfiange wl. 'ch extends in a lateral direction entirely around the barrel, said flange being preferably made continuous and constitut ing the spacing means proper. In addition to the lower flange 15, barrel 14: is provided with an upper flange 16 constituting a finger piece by means of which the barrel may be rdtated and thus raised and lowered along the stern.

In use, the larger and thicker disk 18, made preferablyof crown or comparatively hard glass and provided with a ground depression 19, is placed upon base plate 10,-

plate.

lso as to project. partly beneath barrel 14. The latter is then turned to descend along the stem, and thus tightly l 18 against the plate 10 (Fig. The l smaller and thinner disk 20 made preferably clamp the disk of flint or comparatively soft glass is then superposed upon disk 18, so as to bridge cavity 19, and rest with its edge upon flange 15 (Fig. 4) In this way, the flange will assume its function of a spacer, which will so tilt upper disk 20, as to provide air exit ports to the right and left of that section of the flange which supports disk 20. The de vice being now placed in a heated muffle, disk 20 will soften and gradually sag (Fig. 5) until it becomes seated within cavity 19 and fused to disk 18 (Fig. 6). During the sagging of disk 20 and its intimate union with disk 18, the air will be free to escape from between the disks, through the ports formed by flange 15, as above described, so that no objectionable air bubbles will be formed or retained between the disks and a clean connection will be obtained. After the fusing operation has been completed, the compound glass disk is annealed, slipped off base plate 10 from underneath barrel 14 and then the disk is ground to form the bifocal lens 21 desired (Fig. 7) and thus complete the operation.

The apparatus described, will during thefusing operation not only form a spacer for the glass disks, but it will form a means for clamping the lower disk 18 tightly to the base plate 10, so that the disk is securely held in position. As the barrel is vertically movable along the stem, thicker or thinner the apparatus is adapted for the manufacture of various kinds of lenses. Owing to the fact that the spacing flange 15 entirely encircles barrel 14, an operative portion of such flange will be projected above the lower disk to form a rest for the upper disk without any regard to the particular position of the barrel. That is to say, as the barrel may require a higher or lower position upon the stem to securely clamp the lower disk, it will at all times extend a portion of its flange between the disks to form the required rest for the upper disk[ Finally it may be stated that the barrel is freely accessible to the hand at a convenient distance from the disks, and may thus be readily manipulated for the interposition of the spacer.

If desired, the lower disk may be placed disks may thus be firmly clamped, so that at a distance sidewise away from the supporting flange, in which case the upper disk is made to project laterally beyond the lower disk so as to reach above and be supported by the flange.

I claim: 4

1. An apparatus for making bifocal lenses, comprising a base plate, a stem mounted thereon, a barrel movable along the stem, and disk-spacing means extending laterally from the barrel.

2. An apparatus for making bifocal lenses, comprising a base plate, a screw stem mounted thereon, a threaded barrel engaging the stem, and disk-spacing means extending laterally from the lower end of the barrel.

3. An apparatus for making bifocal lenses, comprising a base plate, a screw stein mounted thereon, athreaded barrel engaging the stem, and provided with a lower disk-spacing flange that extends eircumferentially around the barrel.

4. An apparatus for making bifocal lenses, comprising a base plate, a screw stem mounted thereon, a threaded barrel engaging the stem, and provided with a lower circumferential disk-spacing flange and With an upper finger piece.

HERMAN E. MENDELSSGHN.

Witnesses:

FRANK v. BRIESEN, KATHERYNE K001i.

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