US3738064A

US3738064A - Lens edging machine

Info

Publication number: US3738064A
Application number: US00202147A
Authority: US
Inventors: M Szyferblatt
Original assignee: OPTIMETRIC SYST Inc
Current assignee: OPTIMETRIC SYST Inc
Priority date: 1971-11-26
Filing date: 1971-11-26
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12

Abstract

A lens edging machine for grinding spectacle lenses having elements for grinding a concealed V-shaped bevel of width less than the peripheral thickness of the lens which will follow the curvature of the peripheral edge of the lens, so that the frame in which the lens is mounted may also follow this curvature, while concealing the bevel for a more attractive appearance. The device includes a feeler member directly contacting the forward surface of the lens at a locus of points adjacent the periphery at which a grinding action is instantaneously taking place, which feeler member serves to axially position a grinding wheel as the same contacts the lens periphery. Elements are provided for adjusting the distance of the principal axis of the V-shaped bevel with respect to the forward surface of the lens, which elements may also be adjusted to provide for flat edge grinding where a V-shaped bevel is not desired.

Description

llnited States Patent [191 Szyferblatt 1 LENS EDGING MACHINE [75] Inventor: Morris Szyferblatt, Spring Valley,

[73] Assignee: Optimetric Systems, Inc., Spring Valley, N.Y.

[22] Filed: Nov. 26, 1971 [21] Appl. No.: 202,147

[52] US. Cl. 51/93, 51/99, 51/101 LG [51] llnt. Cl B24b 5/16, B24b 17/04 [58] Field of Search 51/50 R, 50 PC, 99,

[56] References Cited UNITED STATES PATENTS 3,673,738 7/1972 Stern 51/93 2,329,713 9/1943 Goddu 51/101 LG 3,562,963 2/1971 Wrigglesworth..... 51/101 LG 3,315,415 4/1967 Lannom 51/101 X 3,158,967 12/1964 Reaser 51/284 X 3,063,340 11/1962 Dillon 51/284 X 3,673,738 7/1972 Stern 51/93 June 12, 1973 Primary EXaminer-Donald G. Kelly Att0rneyChar1es Ev Temko [57] ABSTRACT A lens edging machine for grinding spectacle lenses having elements for grinding a concealed V-shaped bevel of width less than the peripheral thickness of the lens which will follow the curvature of the peripheral edge of the lens, so that the frame in which the lens is mounted may also follow this curvature, while concealing the bevel for a more attractive appearance. The device includes a feeler member directly contacting the forward surface of the lens at a locus of points adjacent the periphery at which a grinding action is instantaneously taking place, which feeler member serves to axially position a grinding wheel as the same contacts the lens periphery. Elements are provided for adjusting the distance of the principal axis of the V-shaped bevel with respect to the forward surface of the lens, which elements may also be adjusted to provide for flat edge grinding where a V-shaped bevel is not desired.

4 Claims, 8 Drawing Figures PMENIEDJUN I 2 mm 1 LENS EDGING MACHINE This invention relates generally to the field of lens edging machines which are employed to grind the pe-' Most usually, the grinding wheel is caused to follow the profile of a cam which conforms to the normal opening the spectacle frame. The grinding wheel is allowed to progress toward the optical center of the lens until the profile of the cam is reached, at which'point the lens is rotated about its own axis in small increments, so that when the lens has rotated a full 360, the lens blank has been accurately sized. This lens edging operation may be performed with a flat grinding wheel, so that the periphery consists of a curved surface perpendicular to the principal axis of the lens, or, where the lens is to be installed in a spectacle frame which completely encircles the same, it is common to place a V-bevel on the periphery which is engaged by a corresponding recess 1 in the frame. Many opthalmic problems require relatively thick lenses, and when the entire periphery is beveled, ground surfaces are visible extending forwardly and rearwardly of the spectacle frame to present a somewhat less than attractive appearance.

In recent years lens edging machines have been so constructed as to include a pair of grinding wheels, one of which has a cylindrical grinding surface, and the other, which is coaxially mounted includes a small V- shaped groove therein. The operation of the machine is such that a flat grind is first performed which sizes the lens to approximately 2 millimeters of its ultimate size, at which point the carriage which supports the grinding wheels shifts to bring the grooved wheel into play, and the V-bevel approximately 2 millimeters high and 4 millimeters wide at its base is formed by further reducing the flat curved periphery. This operation results in the creation of a V-bevel which lies wholly within a single plane, and where the inner and outer surfaces of the lens are curved, as is very often the case, portions of the lens will extend more forwardly of the spectacle frame than others, again creating an undesirable appearance.

The above effect can be avoided by grinding the V- bevel such that it always remains a constant distance from the forward polished surface of the lens as measured from the ultimately ground periphery, but to accomplish this it is necessary that the grinding wheel having the V-groove in the outer surface thereof be continuously guided to conform to the curvature of the forwardly facing polished surface of the lens.

It is therefore among the principal objects of the present invention to provide an improved lens edging machine capable of grinding a V-bevel upon the peripheral surface of a lens such that its principal axis remains a constant distance from the forward surface of the lens adjacent the ground periphery.

Another object of the invention lies in the provision of an improved lens edging machine having cam follower means in the form of a feeler which contacts the forward surface of a lens being ground, and which imparts the contour of such surface to result in movement of the grinding wheel along an axis substantially parallel to the principal optical axis of the lens.

Yet another object of the invention lies in the provision of improved lens edging grinding structure which may be conveniently incorporated into a wide variety of lens edging machines with relatively little modification.

A feature of the disclosed embodiment lies in the relative simplicity of the mechanical components thereof as contrasted with prior art devices.

These objects and features, as well as other incidental ends and advantages, will more fully appear in the progress of the following disclosure, and be pointed out in the appended claims.

In the drawings, to which reference will be made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views.

FIG. 1 is a fragmentary vertical longitudinal sectional view of an embodiment of the invention, as seen from the plane 1-1 in FIG. 2.

FIG. 2 is an offset horizontal sectional view as seen from the plane 2--2 in FIG. 1.

FIG. 3 is a fragmentary substantially horizontal offset sectional view as seen from the plane 3-3 in FIG. 1.

FIG. 4 is a side elevational view, partly in section, as seen from the righthand portion of FIG. 3.

FIG. 5 is a view in elevation as seen from the lefthand portion of FIG. 4.

FIG. 6 is a bottom plan view, as seen from the lower portion of FIG. 4.

FIG. 7 is a side elevational view of an opthalmic lens ground in accordance with the prior art.

FIG. 8 is a similar side elevational view showing a lens ground by the disclosed embodiment.

In accordance with the invention, the device, generally indicated by reference character 9, comprises broadly: a lower frame element 10, a cover element 11, a lens supporting and rotating element 12, a grinding head carriage element 13, transverse carriage element shifting means 14, carriage element elevating means 15, grinding wheel means 16, and bevel guide means Referring to FIGS. 1 and 2, the frame element 10 is preferably formed as a casting from aluminum or other lightweight metal alloys, and includes a lower wall or floor'22 incorporating leveling means 23. A plurality of supporting bosses 24 serve to mount various components, and are preferably cast integrally. A grinding sink 25 is positioned forwardly and centrally on the lower wall 22, and includes a rear wall 26, a forward 'wall 27 and side walls 28 and 29. A coolant spout 30 introduces a coolant from pump means (not shown) which is collected within the sink 25, and drained through an opening 31 for recirculation in well known manner. A pair of aligned

openings

32 and 33 support the element 12.

The cover element 11 is also preferably formed as a single casting, and includes side walls (not shown), a front wall 40, a rear wall 41, and an upper wall 42 defining an elongated opening 43 therein through which the element 13 projects.

Referring to FIG. 2, the lens supporting and rotating element 12 includes a first shaft 48, an inner end 49 of which mounts a lens engaging means 50 of well known cushioned type. A central portion 51 is supported by an inner bearing 52, and an outer bearing 53, and mounts a driving pulley 54 engaged by a conventional cogged belt (not shown). The outer end 55 includes means 56 for mounting a circular cam (not shown), the axis of which corresponds to the peripheral contour of the lens to be ground. A second shaft 57 is capable of axial reciprocation as well as axial rotation, and is supported by an inner bearing 58, an outer bearing 59 and a driving pulley 60. Axial reciprocation is possible by virtue of a sleeve 61 which surrounds and is splined to the shaft 57. The lens engaging means 62 is axially aligned with the corresponding means 50 at the inner end of the shaft 57, and the outer end 63 is pivotally interconnected with an end 64 of a rocker arm 65 which pivots on a pintle 66. The opposite end 67 of the arm is interconnected with the output shaft 68 of an inner cylinder 69, manually controlled by the user.

The grinding head carriage element 13 is best understood from a consideration of FIGS. 1 and 3 in the drawings, and includes a frame 73 supported on a transversely extending shaft 74. The transverse shifting means 14 includes an arm 75 connected to an extension 76 on a reciprocating member 77 operated by a rearwardly disposed air cylinder 78. First and

second bearings

79 and 80 support the frame 73 on the shaft 74, and the shaft 74, in turn, is supported between trunnions 81 and 82.

The frame 73 includes a bracket 84 mounting an electric motor 85, and a forwardly extending member 86 which mounts a grinding wheel housing, best seen in FIG. 3. The free end 80, thereof, supports a pair of

bearings

89 and 90 in turn supporting the grinding wheel shaft 91 for rotation therein. One end 92 of the shaft 91 mounts a driving pulley 93 interconnected by a belt 94 to an output shaft 95 of the motor 85. The opposite end 96 projects through an opening 97 in a shroud 98 and mounts first and

second grinding wheels

99 and 100, respectively. An end plate 101 is mounted on the shroud, and serves to enclose the end surface of the first grinding wheel.

The grinding wheel 99 is of cylindrical configuration, having an outer surface 102 of cylindricalconfiguration, this wheel serving for rough grinding a lens blank to approximate configuration prior to employment of the second grinding wheel 100. The grinding second wheel includes a V-groove 103 in the peripheral surface thereof adjacent one planar surface 104.

A laterally projecting shaft 105 mounts a bracket 106 in a corresponding bore 107 thereof, the forward end 108 of the bracket mounting a threadedly adjustable cam follower 109 which bears upon an individual lens cam. The rearward end 110 mounts a pin 111 engaged by a spring 112, the free end of the pin activating a micro-switch 113 which serves to actuate a motor (not shown) which rotates the element 12 incrementally as required as the lens blank reaches its approximate contour.

The frame 73 may be raised or lowered manually by means of a handle 114, but is also automatically raised and lowered during a lens grinding cycle through a downwardly extending pintle 115 mounted in a collar 116, the lower end of the pintle being moved by a large air cylinder 117, of somewhat greater diameter than the air cylinder 69.

Driven by the same motor which rotates the element 12 are three

circular cams

118, 119 and 120 mounted on a common shaft 121 which also mounts the pulley 122. These cams actuate the followers of microswitches 123 during a cycle of operation to be subsequently described, the switches controlling valves to the air cylinders.

The bevel guide means 17 is carried by the shroud 98, and is best understood from a consideration of FIGS. 4 to 8, inclusive. Disposed in a generally vertically arranged bore 124 and communicating slot 125 is a shaft 126, the lower end 127 of which mounts a radially extending feeler member 128 having a rounded outer tip 129 adapted to bear directly against the outer polished surface of a lens blank supported by the element 12. At the upper end 130 of the shaft 126 is a collar 131 having an angular displacement indicator 132 cooperating with a fixed pointer 133. Incremental rotational adjustment of the shaft 126 is accomplished by means of a forked link 134 cooperating with a threaded collar 135 and an adjustment screw 136 having a manually engageable terminal 137.

The function of the means 17 is comprehended from a comparison of FIG. 7 with FIG. 8. FIG. 7 illustrates a bevel formed in accordance with prior art methods, wherein the lens 138 having an outer surface 139, an inner surface 140 and a peripheral edge 141 is provided with a V-bevel 142 which lies completely within a single plane perpendicular to the principal optical axis. When the lens 138 is mounted in either a metal rim or one formed of synthetic resinous materials, the protrusion of the lens forwardly in those areas where the bevel is a substantial distance from the forward surface of the lens, as for example the area indicated by reference character 143, the effect of a very thick lens is immediately visible.

By contrast, the lens 144 illustrated in FIG. 8 which is of substantially identical configuration and thickness offers a far better appearance. The outer surface 145, inner surface 146, and peripheral edge 147 are substantially identical with those of the lens 138. However, the V-bevel 148 follows the contour of the outer or forward surface 145, and when the lens is mounted in a frame, the contour of the bevel tends to cause the contour of the spectacle frame to follow, so that the objectionable effect created by the lens 138 is avoided.

During operation of the device, the cycle of events is substantially similar to that encountered in prior art devices. The lens blank to be ground is positioned within the element 12, and the carriage element 13 is positioned so that the second grinding wheel 100 will bear upon the peripheral surface of the blank. When the rough grinding is completed, under control of the

cams

118, 119 and 120, the frame 73 is lifted, and transversely transported to a position where it is opposite the first grinding wheel 99, and subsequently lowered. In this position, the tip 129 of the feeler member 128 will engage the forward surface of the lens, and the shifting means 14 is deactivated by solenoid means (not shown) whereby a spring 151 may urge the frame 73 rightwardly as seen in FIG. 3, assuring that the feeler member will function as a cam follower. At this point, the lens blank has been reduced to within approximately 2 millimeters of its final radius, which is the height of the V-bevel which will be subsequently formed. The fine grinding operation then commences, the frame 73 being free to move laterally in either direction depending upon the contour of the forward surface of the lens blank, whereby the V-bevel is ground in the manner such that its contour will follow that of the forward surface. The constant distance rearwardly of the forward surface at the peripheral edge thereof is regulated by indexing the member 132 with respect to the member 133. When a completely flat peripheral edge is required, the shaft 126 is merely rotated sufficiently far that the cylindrical portion of the first grinding wheel 99 rightwardly of the V-groove as seen in I FIG. 3 bears upon the peripheral surface of the lens.

I wish it to be understood that I do not consider the invention limited to the precise details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.

I claim:

1. In a lens edging machine of a type including first means for supporting a lens for rotation substantially about its own optical axis, a grinding head carriage element axially and laterally shiftable with respect to said first means and having grinding wheel means selectively positioned to abrade the peripheral surface of an unfinished lens blank to predetermined shape, the improvement comprising: a grinding wheel having an outer peripheral surface of generally cylindrical configuration, and having a substantially V-shaped groove extending into said periphery adjacent one edge of said peripheral surface, a feeler member supported by said grinding head element having a free end positioned to contact a polished surface of a lens blank at a point adjacent the peripheral surface thereof instantaneously contacting said grinding wheel, said carriage element including resilient means for urging said feeler into contact with said polished surface of said lens and to follow the contour thereof to shift said grinding wheel such that a V-shaped projection is ground upon the peripheral surface of said lens blank which will duplicate the contour of the locus of points contacted by said feeler member on said polished surface, and spaced a predetermined axial distance therefrom.

2. Structure in accordance with claim 1, including adjustment means for varying said last mentioned distance.

3. Structure in accordance with claim 1 including an elongated shaft mounted for rotational movement about its own principal axis upon said grinding wheel head element, said feeler member being carried by said shaft at one end thereof and extending radially from said axis, and threaded adjusting means for varying the angular position of said shaft with respect to said head element.

4. Structure in accordance with claim 3, said adjusting means being shiftable to a point where said grinding wheel contacts a lens being ground in a peripheral area of said wheel which is clear of said V-shaped groove, whereby said lens blank will be provided with a flat peripheral edge.