US3353303A

US3353303A - Art of edging

Info

Publication number: US3353303A
Application number: US410994A
Authority: US
Inventors: Stern Albert
Original assignee: AIT IND Inc
Current assignee: AIT IND Inc
Priority date: 1964-11-13
Filing date: 1964-11-13
Publication date: 1967-11-21
Anticipated expiration: 1984-11-21
Also published as: DE1296548B; GB1073874A

Description

7 Nov. 21, 1967 Filed Nov. 13, 1964 A. STERN A R T O F E D G I NG Nov. 21, 1967 v A. STERN 3,353,303

' ART OF EDGING Filed NOV. 13, 1964 2 Sheets-Sheet 2 United States Patent Office 3,353,363 Patented Nov. 21, 1967 3,353,303 ART OF EDGING Albert Stern, Lincolnwood, Ill., assignor to A.I.T. Industries, Inc., Skokie, 111., a corporation of Illinois Filed Nov. 13, 1964, Ser. No. 410,994 7 Claims. (Cl. 51105) ABSTRAEIT OF THE DISCLDSURE The art of bevel edging is hereby improved by use of :an abrading tool or wheel having a V-shaped abrading surface, one face of which has a relatively coarse abrading characteristic and the other face of which has a relatively fine abrading characteristic; both faces being simultaneously engaged with a work piece having free-floating movement transversely of the faces and automatically adjusting itself relative to the V-shaped surface to locate the apex of the bevel to one side of the center of the work piece in the direction of the finer face by a distance correlative to the differential in the abrading characteristics of the two faces.

The present invention relates to the art of forming a surface configuration at a predetermined location on a workpiece, and articularly, to automatic formation of a surface having its median plane relatively offset from the median plane of the portion of the workpiece on which the surface is formed.

In the particular embodiments disclosed herein, the invention is concerned primarily with improvements in edge grinding, and has particular reference to novel means for forming beveled edges on articles such as ophthalmic lenses. These embodiments are given by way of example of applicability of the invention, and relate the same to the particular environment in which the invention was conceived and first reduced to practice. As the description proceeds, the broader applicability of the invention will become apparent to those of reasonable skill in the art.

conventionally, eyeglass and like lenses are provided with a V-shaped bevel on the edge thereof to facilitate mounting of the same in a spectacle or other frame. The bevel is customarily formed by feeding the lens edgewise into a peripherally disposed V-shaped groove in a rotary abrading wheel and rotating both the lens and the wheel about their respective axes. In many cases, the wheel and the work may be disposed in a substantially common plane. However, in the case of meniscus shaped articles of non-circular contour, the wheel is preferably set at an angle relative to the lens so that the V-groove will have an effective curvature lying in the same direction as the curvature of the lens itself, so that the edge of the lens will be accurately beveled.

In most prior art edge beveling machines, the lens is chucked in a carriage having relative freedom of movement transversely of the V-groove abrading surface of the wheel, whereby the lens is self-centering relative to the groove and the bevel is formed with its apex disposed centrally of the thickness of the lens edge, which is satisfactory for regular and thin lenses. However, in the case of relatively thick and heavy minus lenses, beveling of the edge results in grinding a significant radial extent of the edge portion of the lens, and the resulting ground surface is objectionable from the cosmetic viewpoint, i.e., the appearance of such ground surface on the front face of the lens is not desired.

To overcome the above stated objection, it has been customary in the art to control the transverse movements of the lens chucking carriage, at least when working with thicker lenses, to prevent the aforesaid self-centering action and to cause the lens to follow a preselected path of movement such that the apex of the bevel is set forwardly of the center of the lens edge, whereby a lesser, unobjectionable portion of the front face of the lens is ground. Such control usually requires one or more cam means associated with the wheel and engageable by the carriage, and imposes upon the operator the tasks of selecting the proper cam for a particular lens and of properly setting the machine to operate on the selected cam or to operate with a self-centering action. Despite all of the precautions that can be and are taken by machine designers and operators, the control means rarely if ever is effective to place the apex of the bevel in the same position over the periphery of the lens, and adjustment and selective use of the cam means is time-consuming and decreases production.

The object of the present invention is to overcome the above stated disadvantages of the prior art practices, and in particular, to provide for automatic self-positioning of the workpiece relative to the tool with the median plane of the surface to be formed offset from the median plane or center of the portion of the workpiece on which the surface is to be formed.

Stated in terms of the specific environment above described, the invention has as its object the provision of improved means whereby a lens, when moved edgewi=e into a V-shaped abrading surface with freedom for selfadjusting movement transversely of said surface, will automatically position itself in offset relation to the V and will maintain the apex of the bevel in the same offset position over the full periphery of the lens.

More specifically, the object of the invention is the provision of an improved tool or abrading wheel having a pair of .angularly related work engaging surfaces which have a differential effect on the workpiece and cause the workpiece to assume a relatively offset position in relation to the median plane of the two surfaces.

A further object of the invention is to provide an improved abrading tool for forming a bevel or the like on the edge of a lens or other article, the tool comprising a V-shaped work abrading surface comprised of opposed relatively inclined faces, one face having a given abrading characteristic, e.g., bearing an abrasive grit of a first size or type, and the other face having a significantly different abrading characteristic, e.g., bearing an abrasive grit of a second size or type significantly different from the first.

In use of the tool above described, I have discovered that the coarser or more rapidly abrading face effectively pulls the workpiece toward that face, and/ or the finer or less rapidly abrading face pushes the workpiece toward the coarser face, whereby the bevel, though straight and accurately formed, is offset from center in the direction of the finer face. By appropriate selection ofthe abrading materials, I have found that the apex of the bevel can be set at any desired position relative to the thickness of the lens, e.g., one-third the thickness from one face and two-thirds the thickness from the other face; one-fifth the thickness from one face and four-fifths the thickness from the other face; etc. In each instance, with repeated trials, the apex of the bevel is always found to be at the predetermined relative location irrespective of the thickness of the lens and irrespective of variations in hardness between lenses. Moreover, the apex of the bevel always maintains the same location relative to the thickness of the lens over the full periphery of the lens, even though the lens (due to the form or outline to which it is ground) may have a peripheral edge that varies in thickness and that undulates relative to the focal plane of the lens.

Thus, the present invention affords the advantages that the lens chucking carriage may be left free to float trans- J versely of the abrading surface for all lenses, that each lens will properly position itself relative to the abrading surface irrespective of the thickness or form of the lens, and that the prior art carriage guiding mechanisms and the limitations they impose on personnel and production may now be eliminated.

Other objects and advantages of the invention will become apparent in the following detailed description.

Now, in order to acquaint those skilled in the art with the manner of making and using the improvements provided according to this invention, I shall describe, in connection with the accompanying drawings, preferred embodiments of abrasive grinding wheels made in accordance with my invention, and the preferred manners of making and using the same. 7 V V In the drawings, wherein like reference numerals indicate like parts: 7

FIGURE 1 is a plan view of a lens edging machine showing the preferred relationship between the abrading wheel and a miniscus shaped lens intended to be ground to non-circular contour or outline;

FIGURE 2 is an enlarged fragmentary plan view of the lens and beveling wheel illustrating the conventional relationship therebetween; v v

FIGURES is a further enlarged fragmentary crosssection of the peripheral portion of an abrading wheel formed in accordance with the present invention;

FIGURE 4 is a view similar to FIGURE 3 of a second embodiment of the wheel; I

FIGURE 5 is a view similar to FIGURES 3 and 4 showing a third embodiment of the wheel;

FIGURE 6 is a view similar to FIGURES 3 to 5 showing a fourth embodiment of the wheel; 7

FIGURE 7 is a view similar to FIGURE 2 illustrating the self-positioned offset beveling afforded according to this invention; and

FIGURE 8 is a view similar to FIGURE 7 showing a different ratio or degree of offset.

Referring to the drawings, FIGURE 1 is a somewhat schematic representation of one embodiment of an edging machine described in my 'co'pending application Ser. No. 411,332, filed Nov. 16, 1964, now Patent No. 3,332,172. This machine comprises a'mainframeor base 10 mounting a movable frame 12 and a secondary frame 14. The frame 12 is reciprocal towardand away from the frame 14 and mounts a work carriage 34 including chuck means 1'6 for mounting a lens W or other workpiece in a position gen erally parallel to the path of reciprocatory movement of the frame 12. The carriage 34 is mounted on the frame 12 for free floating movement transversely of the path of movement of the frame, i.e., generally parallel to the axis of the chuck means 16 and the lens W. Motor means 17 for rotating the chuck 16and the lens or other workpiece is appropriately mounted on the carriage 34 or frame 12, as may be ascertained in greater detail by reference to my copending application.

The frame 14 mounts means 18 in juxtaposition to the edge of the workpiece for performing one or more finishing operations on said edge. In the illustrated machine, the means '18 comprises an abrading wheel having a pcripherally disposed V-shaped groove therein, and a motor 19 is provided on the frame 14 'for rotating the wheel to cause the same to form a bevel on the edge of the lens. The wheel and its driving motor may be so set on the frame 14 that the plane of the wheel parallels the plane of the workpiece, but for grinding meniscus shaped articles of non-circular contour it is preferable, as shown, to set the wheel at'an angle of about 45 to the workpiece so that the V-groove will have an effective curvature in the same direction as the curvature of the lens o'r'other article. The advantages of such an arrangement are described in Patent 2,674,068. Irrespective of the plane of the wheel, the V-groove in the periphery thereof is preferably disposed with its bisector perpendicular t0 the axis of the chuck 16 and thus essentially p r llel. t the workpiece.

The latter arrangement is illustrated in greater detail in FIGURE 2 wherein the abrading wheel 18 is shown to be set at an angle of 45 to lines parallel and perpendicular to the axis of the chuck means 16, and to be provided with a peripherally disposed V-shaped groove the bisector of which forms or is coincident with said perpendicular line. The V-groove is formed by a pair of abrading or working faces that are inclined relative to one another and to the lens W, the two faces suitably defining an angle of about therebetween and having a common apex coincident with the bisector of the angle, i.e., an angle of 57 /2" is defined between each face and the bisector. In conventional practice, with the carriage 34 and the lens W mounted for free floating movement in the direction transversely of the groove, preferably at right angles to the bisector of the groove, the lens will automatically center itself in the groove whereby the bevel imparted to the edge of the lens will have its apex A located centrally of the lens, as is shown in FIGURE 2.

In differentiation from the prior art, I provide a working instiumentality, e.g., a bevel grinding wheel, that is comprised of two widely diverse abrading or finishing characteristics which have the effect of converting the aforesaid self centering action into an automatic self locating action wherein the workpiece is automatically offset a predetermined extent in a predetermined direction from a centered position relative to the V. Specifically, referring to FIGURE 3, I provide an abrading wheel 18a essentially the same as the wheel 18 except that the front and

rear faces

50a and 52a of the V-groove thereof are formed by or carry abrasive particles of significantly different abrading characteristics. This may be accomplished by using abrasive particles or grits of the same kind but of different sizes, and/or by using particles of different characteristics, for example, silicon particles on one face and carbon or diamond grit on the other.

The differential between the abrading characteristics of the faces must be quite substantial if a significant offsetting of the workpiece is to be obtained. When bevel edging glass lenses and the like, I prefer to work with diamond grinding wheels, and in this environment I have found that I can effect any desired, controlled degree of offset by variation in the size differential between the diamond particles or grits used on the two faces 50a and 5211. For example, wit-h reference to FIGURE 3, by using a diamond grit size of 30 microns on the front face 50a (i.e,, the face that contacts the front of the lens) and a 250 mesh grit (about 63 microns) on the rear face 52a, I have found that when a free floating lens is moved edgewise into the V-groove the lens automatically takes up a position wherein its center is offset toward the rear face 52a by a distance equal to about one-sixth the thickness of the lens. The result is that the apex A of the bevel formed on the edge of the lens is located one-third the lens thickness from the front face of the edge and two-thirds the lens thickness from the rear face or margin of the edge, as is shown specifically in FIGURE 7.

As another example, by using a diamond grit size of 30 microns on the front face 50a and a 270 mesh diamond grit (about 5 3 microns) on the rear face 52a, I have found that when a free floating lens is moved edgewise into the V-groo've the lens automatically takes up a position wherein its center is offset toward the rear face 52a by a distance equal to about one-tenth the thickness of thelens. The result is that the apex A of the bevel formed on the edge of the lens is located two-fifths the lens thickness from the front face of the edge and three-fifths the lens thickness from the rear face or margin of the edge, as shown speci fic ally in FIGURE 8.

While FIGURES 3, 7 and 8 illustrate wheels ideally suited for bevel edging eyeglass lenses, wherein it is usually desired to set the apex of the bevel forwardly of the center of the lens edge (i.e., to the left as viewed in the drawings), it will be apparent that whenever it is desired to displace or offset the apex of the bevel in the opposite direction, i.e., rearwardly or to the right, it is only necessary to reverse the locations of the two abrading materials; that is, to put the coarser material on the front face 50a and the finer material on the rear face 52a.

Different sizes of grits may be used on the faces to control the rate of grinding and the fineness of the ultimate finish imparted to the lens or other article. According to the present invention, a significant differential is provided between the abrading characteristics of the two faces to afford the automatic offset action above described, but this offset may be obtained by the differential between two rather coarse grits or the differential between two rather fine grit sizes, thereby to afford the offset while simultaneously providing either a rough grinding action or a fine finishing action, as may be desired. Thus, it is to be emphasized that it is not the grit size that matters, but the differential between the two. From the examples above given, those skilled in the art will be able, quickly and conveniently, to make appropriate selections of grit sizes and/ or types to obtain any degree of offset desired, and at the same time substantially any rate or degree of working or finishing desired.

It is further to be observed that the location of the apex of the bevel is always in the predetermined ratio or relative position irrespective of the thickness of the edge and irrespective of the fact that the edge thickness may vary considerably over the periphery of a meniscus shaped article of non-circular contour. In other words, if the two faces of the wheel are so constructed as to set the apex of the bevel one-third the thickness of the lens edge from one face of the lens, the apex of the bevel will always be one-third the thickness from that face whether the edge be thick or thin.

When working with diamond abrading wheels, it is customary to bond the diamond grits to preformed working faces machined on a unitary steel base or blank. According to the present invention, the blank disc is machined in the customary manner and diamond grits of the first selected size are bonded in any conventional manner onto the respective one of the

faces

50a and 52a. Then, in a second bonding step, the grits of the second selected size are bonded to the other of the

faces

50a and 52a to complete the wheel of FIGURE 3. During each bonding step, the face 50a52a not being worked on at the time may be shielded or masked in any manner conventional in the art.

Alternatively, the wheel may be made in two separate parts (as depicted, for example, by the dotted line 54a in FIGURE 3) each presenting one of the faces 50a and 520; with the two parts subsequently being bonded or otherwise secured together. This method is preferred when the wheel is formed in its entirety of bonded abrasive particles or the like. Specifically, a first disc bearing the face 50a may be molded in the depicted shape and a second disc bearing the face 52a may be molded in that shape, and the two discs may then be secured together in intimately abutted relation, as by adhering or bonding the same to one another or by passing an arbor through their center holes and bolting the two discs thereon. As a further alternate, two cylindrical abrasive discs may be secured together and the periphery thereof may then be machined, dressed or otherwise worked to form a V-groove presenting

diverse faces

50a and 52a.

A further feature of the abrading wheel of this invention is formation of the same such that both the fine finishing face and the ape-x portion of the bevel are formed from the finer grit, thus to grind a bevel with a sharp and accurately formed vertex; specifically by making one face and the apex portion of the V-groove of the finer grit material and only the remaining portion of the other face of the coarser grit material. As shown in FIGURE 4, the rear face 52b of a wheel 18b may be comprised of a peripherally outward major face area 52b-1 which carries or presents the coarser grit material and a minor face portion 52b2 of limited extent contiguous to the apex of the V-groove which carries, presents or is formed of the same grit material as the front face 505. By virtue of this arrangement, the apex of the bevel is accurately formed on the edge of the lens and with a fine finish.

To facilitate manufacture of the wheel 18b, I form the same of two separate parts which may subsequently be integrated or combined by suitable fasteners, adhesives or the like. Specifically, I make a first circular disc 60b and machine or otherwise work the peripheral portion of the same to define the working face 5%, the apex of the V-groove and the minor face portion 52b-2 of the face 52b. To the face portions 50b and 52b-2, I then apply the selected grit in any manner conventional in the art. A second disc 62b is then formed in much the same manner, but to the different configuration shown, and the two discs are then secured together. If the wheel is made entirely of bonded abrasive particles, two cylindrical discs may be bonded together and dressed to the groove configuration illustrated in FIGURE 4. To form a rearwardly offsetting wheel, disc -60b would be the coarse one, disc 62b would be the fine one and their line of separation would fall along the dotted line 56b.

In FIGURES l to 4, 7 and 8, I have illustrated abrading wheels particularly suited to the angular embodiment of the improved edging machine shown in my copending application, previously identified. It is to be appreciated that the invention is equally applicable to other angle grinding machines such, for example, as that shown in Patent 2,674,068, see FIGURE 5 hereof; and to in-line edging machines such as the in-line embodiment of the machine of my co-pending application, see FIGURE 6 hereof; and to many other types and styles of machines for forming surface configurations on the edges or other portions of workpieces. The abrading wheels of FIGURES 5 and 6 are identical in principle to the wheel of FIGURE 3, and may if desired be constructed in accordance with either FIGURE 3 as shown in solid lines, or FIGURE 4 as indicated by dotted lines, with the exception that the V-groove has a different location or disposition at the periphery of the wheel for cooperation with the lens as it is held by the respective machine. Due to the similarity of the wheels, and the correspondence of the reference numerals applied thereto, further description of FIGURES 5 and 6 is believed unnecessary.

In view of the foregoing, it is manifest that the objects and advantages of the invention have been shown herein to be attained in a convenient, economical and practical manner.

While I have shown and described what I regard to be the preferred embodiments of my invention for use in the particular art of bevel edging eyeglass lenses, it is to be appreciated that rearrangements and modifications may be made in the illustrated embodiments and that the invention may be applied in other arts without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. A finishing instrumentality for forming a bevel at a predetermined location on a work piece, comprising a body including a pair of working faces disposed at an inclination to one another and intersecting in a V-shape, the major part of one of said faces outwardly from the apex of the V being coarse relative to the other face, said other face and the part of the one face adjacent the apex of the V being fine relative to said coarse part, said faces being simultaneously engaged with the work piece whereupon said coarse part of said one face attacks a greater portion of the work piece than said fine face and said fine face and said fine part of said one face form the apex of a V-shaped bevel on the work piece.

2. A rotary abrading wheel for forming a bevel at a predetermined location on a work piece, comprising a pair of interconnected disks defining a pair of circular abrading faces concentric with the disks, said faces being disposed at an inclination to one another and intersecting in a V-shape, one of said disks defining one of said faces and the adjacentpart of the other of said faces, the other of said disks defining the remainder of said other face, said one disk presenting on the face portions thereof abrasive particles of a first abrading characteristic, said other disk presenting on the face portion thereof abrasive particles of an abrading characteristic significantly different from and coarser than the first, said faces being simultaneously engaged with the work piece whereupon said other disk attacks a greater portion of the work piece than said one disk and said one disk forms the apex of the bevel on the work piece.

3. A process for bevel edging meniscus shaped articles such as lenses with the apex of the bevel offset from the center of the edge of the lens, comprising the steps of engaging the edge of the article with an abrading Wheel having a peripherally disposed generally V-sha-ped abrading surface for reception therein of said edge With the curvature of the article conforming generally to the curvature of the abrading surface, said surface being comprised of opposed relatively inclined faces, the face adjacent which the convex surface of the article is disposed having a given abrading characteristic and the other face having a significantly coarser abrading characteristic, rotating both the wheel and the article about their respective axes, and simultaneously accommodating free-floating move- 'ment of the article transversely of said faces.

4. In an edging machine having frame means for supporting an edging in'strumentality and carriage means for mounting a work piece for edgewise movement toward and away from the instrumentality and for substantially free floating movement transversely of the instrumentality, the improvement residing in the provision of an instrumentality having a pair of edge Working faces inclined relative to one another and the edge of the work piece, one of said faces being relatively coarse and the other being relatively fine, said faces causing the work piece to locate itself relative thereto with the median plane of the work piece offset from the juncture of said faces in the direction of said relatively coarse face.

5. In a bevel edging machine having means for supporting and rotating an abrading wheel and carriage means for mounting a lens for rotary movement about its axis, edgewise movement toward and away from the Wheel and substantially free floating movement transversely of its axis, the improvement residing in the provision of an abrading wheel having a peripherally disposed generally V-shaped groove therein for reception of the edge of the lens, said groove including a pair of abrading faces inclined relative to one another and defining therebetween an angle the bisector of which extends generally parallel $3 to the lens, one of said faces having a relatively coarse abrading characteristic and the other having a relatively fine abrading characteristic, said faces causing the lens to locate itself in said groove with the center of the edge of the lens offset from the said bisector of the angle in the direction of said relatively coarse face.

6. A process of bevel edging a Work piece with a finishing instrumentality comprised of a body including a pair of working faces disposed at an inclination to one another, one of said faces being coarse relative to the other and said other face being fine relative to the one, comprising the steps of simultaneously engaging both faces of the finishing instrumentality with the work piece, and accommodating free-floating movement of the Work piece transversely of said faces during finishing, whereby the apex of the bevel formed on the Work piece is automatically offset from the center of the work piece in the direction toward the relatively fine face.

7. A process of bevel edging a work piece with an abrading device including a pair of working faces disposed at an inclination to one another, one of said faces having a relatively fine abrading characteristic and the other face having a relatively coarse abrading characteristic affording a significant differential in the abrading characteristics of the two faces, comprising the steps of simultaneously engaging both faces of the device with the work piece, and accommodating free fioating movement of the workpiece transversely of said face during finishing, whereby the apex of the bevel formed on the edge of the article is automatically offset from the center of 'the edge in the direction toward the face having the relatively fine abrading characteristic by a distance correlative to the differential in the abrading characteristics of the two faces.

References Cited UNITED STATES PATENTS 303,314 8/1884 Neuert 51206 X 440,682 11/1890 Wood -51206 687,962 12/1901 Hyde 51206 1,243,241 10/1917 Arnes 51-95 1,630,264 5/1927 Gunning 51101 2,329,713 9/1943 Goddu 51-101 2,674,068 4/1954 Eves et al. 1'.. 51--l01 3,210,890 10/1965 Lannom 5l-l01 FOREIGN PATENTS 921,586 1/ 1947 France.

1,224,927 2/1960 France.

LESTER M. SWINGLE, Primary Examiner.

Claims

4. IN AN EDGING MACHINE HAVING FRAME MEANS FOR SUPPORTING AN EDGING INSTRUMENTALITY AND CARRIAGE MEANS FOR MOUNTING A WORK PIECE FOR EDGEWISE MOVEMENT TOWARD AND AWAY FROM THE INSTRUMENTALITY AND FOR SUBSTANTIALLY FREE FLOATING MOVEMENT TRANSVERSELY OF THE INSTRUMENTALITY, THE IMPROVEMENT RESIDING IN THE PROVISION OF AN INSTRUMENTALITY HAVING A PAIR OF EDGE WORKING FACES INCLINED RELATIVE TO ONE ANOTHER AND THE EDGE OF THE WORK PIECE, ONE OF SAID FACES BEING RELATIVELY COARSE AND THE OTHER BEING RELATIVELY FINE, SAID FACES CAUSING THE WORK PIECE TO LOCATE ITSELF RELATIVE THERETO WITH THE MEDIAN PLANE OF THE WORK PIECE OFFSET FROM THE JUNCTURE OF SAID FACES IN THE DIRECTION OF SAID RELATIVELY COARSE FACE.