US2419543A - Means and methods of abrading - Google Patents

Description

April 29, 1947. c. A. ELLIS YETAL 2,419,543

MEANS AND METHODS OF ABRADING Filed Sept. 4, 1944 2 Sheets-Sheet 1 w ti 1-- 8 38 0' 5 INVENTOR.

April 29, 1947- c. A. ELLIS arm. 2,419,543

MEANS AND METHODS OF ABRADING El led Sept. 4, 1944 1 2 Sheets-Sheet 2 I \NVENTOR CHBRLES H. ELL/S LHMQENCE A. SEVERY BY 86/ M;

ATTORN Y Patented Apr. 29, 1947 MEANS AND METHODS OF ABRADING Charles A. Ellis and Lawrence A. Severy, Southbridge, Mass., assignors to American Optical Company, Southbridge, Mass., a voluntary association of Massachusetts Application September 4, 1944, Serial No. 552,604

15 Claims.

This invention relates to curve generating means and has particular reference to novel means for obtaining surfaces of compound curvatures and methods of obtaining the same.

One of the principal objects of the invention is to provide novel means and methods of obtaining surfaces of compound curvatures such as are embodied in producing ophthalmic lenses commercially known in the art as toric lenses.

Another object is to provide curve generating means which will enable independently controllable curves to be simultaneously formed in the two major meridians of a lens.

Another object is to provide means for ontrolling the depth of grinding of compound surfaces of the character described.

Another object is to provide novel means and methods of controlling the curves in the major meridians of an ophthalmic lens whereby the curves are generated by a cupped grinding tool and the curvatures of said major meridians, which may be plus, or minus, or even plus and minus curvatures, are controlled by the angular relation of the tool with respect to the surface of the blank in said two major meridians.

Another object is to provide means in an apparatus of the character described whereby the angle of the tool may be synchronously shifted from one major position of ,movement to another during the abrading in combination with means for altering said majorpositions of movement.

Another object is to provide a novel method of producing compound surface curvatures on an article.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings and it will be apparent that many changes may be made in the details of construction, arrangement of parts and steps of the processes or methods shown and described without departing from the spirit of the invention as expressed in the accompanying claims. We, therefore, do not wish to be limited to the exact details of construction, arrangement of parts and methods shown and described as the preferred form only has been given by way of illustration.

Referring to the drawings:

Fig. 1 is a diagrammatic side elevational view of the device embodying the invention;

Fig. 2 is a face view of the abrading tool embodying the invention;

Fig. 3 is a perspective view of a blank having the resultant surface curvatures generated thereon according to the present invention;

Fig. 4A and Fig. 4B are cross sectional views taken along the major meridians of a blank having resultant plus or convex surface curvatures generated thereon;

Fig. 5A and Fig. 5B are cross sectional views of a blank having resultant minus and plus surface curvatures respectively generated thereon;

Fig. 6A and Fig. 6B are cross sectional views of a blank having resultant concave or minus surface curvatures generated thereon;

Fig. 7 is a side elevational view of a portion of Fig. l, somewhat enlarged and with certain parts thereof broken away to show the pivotal mounting for the abrading tool; and

Figs. 8A, 8B and 8C are diagrammatic views; showing in Fig. 8A the tool in its neutral position, in Fig. 8B the tool in an angled position for generating a convex surface curvature and in Fig. the tool in another angled position for generating a concave surface curvature.

Referring more particularly to the drawings wherein like characters of reference designate like parts throughout the several views, the device embodying the invention comprises a spindle 4 on which a lens holder 5 is supported. A lens blank 6 is preferably secured to the lens holder 5 by a suitable layer of pitch or other adhesive I. The spindle 4 is reciprocally supported internally of a bearing 8 whereby the said lens holder and blank 6 may be raised or lowered with the uppermost position of movement thereof determined by a suitable scale 9 and indicator Ill. The indicator I0 is carried by an adjustable stop Ill. A lever ll pivotally supported at I2 is adapted to engage the lower end of the spindle 4 and to raise said spindle under the action of a weight I2 hung from the opposed end of the lever. The movement of the lever is limited by the adjustable stop ID.

The spindle 4 is provided with a suitable pulley or the like Il' connected through a belt I2 to a pulley l3. The pulley I3 is mounted on a shaft l4 rotated by a suitable reduction gearing l5 through a motor I6. A gear I! carried by the spindle 4 is connected through a suitable idler gear l8 to a gear 19 carried by a spindle 20. The spindle 20 has a disc 2| pivotally connected thereto as illustrated at 22 whereby the said disc 2| may be angularly adjusted, the said angling being brought about by a link 23 pivotally connected at 24 to said disc 2| and pivotally connected to a sleeve 25 reciprocally mounted on the spindle 20. The sleeve 25 is adjusted longitudinally of the spindle 20 by means of a yoke 59 carried by the slide member 26. The slide 26 is carried by a fixed wall member 21 and is locked in adjusted position by a clamp 28. The slide 26 is provided with an indicator 29 cooperatively functioning with a scale 30 for determining the position of adjustment of the sleeve 25. Movement of the sleeve 25 longitudinally of the spindle 20, acting through the link 23, causes the disc 2| to be adjusted to a given fixed angular position. The disc 2| is of a size and controlled in detail hereinafter.

contour, the functions of which will be described However, it should be here noted that preferred forms of the disc 2| would include circular and elliptical contours of suitable sizes to give adequate amounts of angling to the shaft 32 and thus to the tool 3| for the curvature or curvatures to be generated.

A ring or cupped grinding tool 3| is mounted on a shaft 32 rotatably supported in spaced bearings 33 and 34 carried by a bracket 35. The bracket 35 is pivotally connected at 36 to a suitable support 36' with the said center line of the pivot 36 being coaxial with the center of the cross sectional curvature of the abrading surface of the cup or ring tool 3| and with the said center line of the pivot intersecting the longitudinal axis of the spindle 4. The shaft 32 is provided with a pulley 31 adjacent the upper end thereof which is'connected through a suitable belt 38 to a pulley 39 driven by the motor IS.

The bracket 35 is connected at 35 to a link 40 which has its opposite end pivotally connected at 40' to an intermediate part of a lever 4| slideably supported in a bearing 42. The bearing 42 is in turn pivotally connected to a bracket 43 carried by a slide member 44. The slide member 44 is slideably supported in a wall 45 and is locked in adjusted position by means of a clamp screw or the like 46. The bearing 42 is provided with an indicator 4! which functions cooperatively with a suitable scale 48 for controlling the position of adjustment of the bearing 42. The lever 4| is adapted to oscillate about the center 48 of the pivotal connection of the bearing 42 with the bracket 43. By movement of said bearing longitudinally of the lever 4| the effective length through which the lever 4| acts may be varied. The lever 4|, adjacent the rear end thereof, is pivotally connected at 49 to-a slide rod 50 slideably supported in a bearing The slide rod 50 is provided with a contact member 52 adapted to engage the periphery of the disc 2| and is held in engagement with said disc 2| by a spring or the like 53.

It is to be noted that the spindle 4 is provided with a spline portion 54 which will permit the said spindle to be moved longitudinally through the bearing 8, the pulley H and the gear I! while retaining said pulley and gear in interlocked driving relation therewith.

The abrading tool 3| as shown in Fig. 2 is of a circular shape preferably having its abrading surface impregnated with diamond particles or other suitable abrasive means with the said abrading surface being of circular cross sectional contour whereby the said tool may be moved to diiferent angular relations. with the lens blank without changing the positional relation of said tool with said blank. This causes a difierent abrading portion of the tool to be engaged with the blank at diiferent angular adjustments of said tool.

The curve generating principle of such an abrading tool is commonly known in the art of spherical surface generation with the diameter of the tool and its angle with respect to the rotational axis of the blank being the controlling factors as to the curve generated.

Referring more particularly to the operation of the device the curve to be generated in one of the major meridians of the blank, for example, curve A, as indicated in Fig. 3, is controlled by angling the tool 3| to the left about the pivot 36 and with respect to the axis of rotation of the blank 5 by the rotation of the disc 2| to the posi- 4 tion indicated by Fig. 1. The maximum angle of the tool 3| to the left is at such time determined by the angular adjustment of the disc 2| relative to shaft 20 and the adjustment of bearing 42, that is, when the lever 4| reaches its extreme position of throw in the direction of the arrow 55. the tool 3| will be angled to a position to generate a curvature along meridian A. This produces the curve desired in one of the major meridians of the blank. The curve in the opposed major meridian B, as indicated in Fig. 3, is controlled by the maximum position of movement of the lever 4| in the opposite direction, that is, in the direction of the arrow 56 as brought about by the angling of the disc 2| through degrees.

It is first pointed out that he scale 48 and indicator 41 will enable the operator to determine the position at which the bearing 42 must be set to obtain the effective lever arm length desired between the points 48' and 49; The scale 30 and indicator 29 will enable the operator to determine the set angle of the disc 2|.

Let us assume, for example, that the disc 2| is of circular shape and when angled, as indicated in Fig. 1 and as described above, the extent of ratio of movement of the lever 4| in the directions 55 or 55 will be controlled by the extent of said angling of the tool 3| and by the diameter of the disc 2|. This ratio is such as to tilt the tool 3| to the maximum positions required to produce the curves desired in the two major meridians of the lens. This gives the maximum throw of the lever 4| or anglin of the tool in said respective meridians A and B. In the device as shown the initial angling of the tool at the maximum movement of the lever 4| in the direction 56 is controlled by adjustment of the sleeve 42 longitudinally of the lever 4| and this provides means whereby the base curve B may be varied according to the prescriptive requirements and will produce a concave surface or negative curvature on the blank 6. The ratio of difference between curves A and B is controlled by the angling of the disc 2| to allow movement of the tool 3| in the opposite direction 55 and since in the adjustment shown for the disc 2| the tool 3| pivots only as far as its neutral position no curvature in the meridian A will be produced. However, should the disc 2| be adjusted to a slightly greater angle relative to the shaft 20, movement of the tool to the left of the neutral position would occur and a convex surface curvature would be produced on the meridian A. On the other hand, if disc 2| is angularly adjusted in the opposite direction somewhat from the position shown in Fig. 1, the tool 3| in its tilting movement toward the left will only reach a point to the right of the neutral position and thus a concave surface curvature will result in the meridian A.

Should a disc of smaller diameter'be used at 2| and the device adjusted so as to allow all of the tilting action of the tool 3| under the influence of this disc to take place to the left of said neutral position convex surface curvatures will be produced on the major meridians A and B. Thus a lens blank having two different convex curvatures as shown by Figs. 4A and 4B respectively, or a lens having a. concave curvature and a convex curvature as shown by Figs. 5A and 5B, or a lens having two concave curvatures-as shown by Figs. 6A and 63 'may be produced.

It has been stated above that the disc 2| has been assumed to be circular in contour. The contour shape, however, of said disc may be varied as desired to bring about a difierent rate of change between the power of the curves A and B. For example, it may be desired to form said disc to an elliptical shape.

During the curve generating of the device the blank 6 is continuously rotated about the axis of the spindle 4 and the ring or cupped tool 3| is likewise continuously rotated preferably at a higher rate of speed. The related speeds are controlled by the reduction gearing l5. As the ring or cupped tool 3| is rotated the spind e 20 is simultaneously rotated thereby causing the disc 2| to rotate and, through its engagement with the contact member 52, will simultaneously cause the lever 4| to be swung about the pivot 48'. By reason of the fact that the lever 4| is connected through the link 40, with the bracket 35 supporting the tool spindle, the angle of the p e 32 will be changed and caused to move from one extreme angle in the direction of the arrow 55 to the extreme angle in the direction of e arrow 56 with the related speed of rotation' of the blank 6 being so controlled that the maximum tilt in one direction will occur in one of the jor meridians of the blank and the maximum ti Qin the other direction will occur in the other major meridian. This swinging movement of the lever:

4| will cause the bracket 35 to be angled about the center of its pivot 36 thereby changing the angular relation of the tool with respect to the blank during the abrading.

Any slack which may be introduced in the belt 38 durin the angular movement of the bracket 35 can be taken up by a suitable idler pulley 51 pivotally supported at 58 and held in engagement with the belt through the provision of a suitable spring or weight (not shown) tending to constantly urge the pulley 51 toward the belt. It will be seen, therefore, that when the point on the disc 2| nearest the axis of rotation of the spindle 20 engages the member 52, the bracket 35 will be at its maximum angle in the direction of the arrow 55; and when the highest point on the disc 2| is in engagement with the member 52, the bracket will be moved to its maximum angle in the direction of the arrow 56 thereby causing the tool 3| to generate the desired curvatures in the meridians A and B of the lens. This movement from one major position to the other is brought about by a synchronous action so that a toric curve is generated on the surface of the blank. By controlling the stop position of the lever through the scale 9 and indicator ID, the extent of the material removed from the blank may be controlled.

From the foregoing description it will be seen that simple, efficient and economical means and method have been provided for accomplishing all of the objects and advantages of the invention.

Having described our invention, we claim:

1. A device of the character described comprisin a cupped type abrading tool and a holder for supporting a lens blank thereon for association with said tool, means for supporting said tool for rotation and for tilting movement about a fixed axis relative to the blank, means for es tablishing the range of tilt of said tool and for moving said tool from one maximum angular position to another, means for varying said range of tilt, means for rotating said holder to rotate said blank and means for causing said blank and tool to move toward each other during said abrading, the means for causing rotation of the holder and the means for causing angular movement of the tool being so interconnected that the maximum angle of movement of the tool in one direction will take place in one meridian of the blank and the maximum angle of movement of the tool in the other direction will take place in another meridian of the blank to thereby form a toric lens surface.

2. In a device of the character described a cupped abrading tool supported for tilting movement about a given fixed center, variable means for controlling the range of tilt of said tool from one maximum position to another, means for engaging a lens blank with said tool, means for rotating said tool, means for rotating said engaging means, the means for causing rotation of said engaging means and the means for causing angling of said tool from one maximum position to the other being so re ated that the tool will be angled to its maximum position of tilt in one direction when one major meridian of the blank is engaged by the tool and will be angled to its maximum position of tilt in the opposite direction when the other major meridian of the blank is engaged by the tool.

3. In a device of the character described the combination of a cupped tool supported for tilting movement about a given fixed center, said tool having a curved abrading surface throughout one edge thereof with its center located at the center of tilt, means for supporting a lens blank for movement toward and away from said abrading tool along an axial line intersecting the axis of the center of tilt of the tool, means for tilting said tool from one major position to another, means for rotating said tool and means for rotating said blank supporting means, the means for causing rotation of said blank supporting means and the means for causing tilting of said tool bein so related that the maximum tilting in one direction will occur at one major meridian of the blank and the maximum tilting in the opposite direction will occur at the other major meridian of the blank.

4. In adevice of the character described the combination of a cupped tool supported for tilting movement about a given fixed center, said tool havinga curved abrading surface throughout one edge thereof with its center located substantially concentric with the center of tilt, means for supporting a lens blank for movement toward and away from said ahrading tool along an. axial line intersecting the axis of the center of tilt, means for tilting said tool from one extreme position to another, means for rotating said tool and means for rotating said blank supporting means, the means for causin rotation of said blank supporting means being so related with respect to the means for causing tilting of said tool that the maximum tilting in one direction will occur at one major meridian of the blank and the maximum tilting in the opposite direction will occur at the other major meridian of the blank, and means for altering the extent of tilt in said opposite directions.

5. In a device of the character described the combination of a cupped tool supported for tilting movement about a given fixed center, said tool having a curved abrading surface throughout one edge thereof with its center located substantially concentric with the center of tilt, means for supporting a lens blank for movement toward and away from said abrading tool along an exial line intersecting the axis of the center of tilt, means for tilting said tool from one major position to another, means for rotating said tool and means for rotating said blank supportingmeans, the means for causing rotation of said blank supporting means being so related with and interconnected to the means for causing tilting of said tool that the maximum tilting in one direction will occur at one major meridian of the blank and the maximum tilting in the opposite direction will occur in the other major meridian or the blank, and means for altering the range of tilt.

6. In a device of the character described the combination of a bracket pivoted adjacent one end thereof for tilting'about a given center, a cupped tool rotatably supported by said bracket, said cupped tool having a curved abrading surface in the direction of a section of said tool with the center of said curve substantially coaxial with the axis of the pivot of the bracket, means for supporting a' lens blank for movement toward and away from said tool about a longitudinal axis intersecting the axis of said pivot, means for rotating said blank supporting means, a lever supported for movement about a pivot, means for varying the position of said lever pivot, said lever being connected with .the bracket through a link member, a contact member carried by said lever, a disk-like member engaging said contact member, means for angling said disk to variably set positions, means for rotating said disk, means for retaining said contact member in engage ment with said disk and means for controlling the extent of movement of said blank toward said abrading tool during the abrading operation.

'7. In a device of the character described the combination of a bracket pivoted adjacent one end thereof for tilting about a given center, a cupped tool rotatably supported by said bracket, said cupped tool having a curved abrading surface in the direction of a section of said tool with the center of said curve substantially coaxial with the axis of the pivot of the bracket, means for supporting a lens blank for movement to-o ward and away from said tool about a longitudinal axis intersecting the axis of said pivot, means for rotating said blank supporting means, a lever supported for movement about a pivot, means for varying the position of said lever pivot, said lever being connected with the bracket through a link member, a contact member carried by said lever,

a disk-like member engaging said contact member, means for angling said disk to variably set positions, means for rotating said disk, means for retaining saidcontact member in engagement with said disk and means for controlling the extent of movement of said blank toward said abrading tool during the abrading operation, the rotation of said blank supporting means and of said disk being so related as to cause the cupped tool to'assume a given angular relation with theblank at one major meridian thereof and to cause said cupped tool to assume a given diflerent angular relation with said blank at another major meridian thereof.

8. The method of generating compound surface curvatures on an article comprising rotating said article about a first axis and while in engagement with a rotating cup-like abrading tool, angling said tool about a second fixed axis normal to and intersecting said first axis to two given angular positions with respect to the article during the rotation thereof, and causing the article to rotate in such a manner that the tool will assume one of its angular positions in one of the major meridians of the article and will assume its other angular position in another major meridian of the article as said tool and article are being rotated.

9. The method of generating compound surface curvatures on an article comprising rotating said-article about a first axis and while in engagement with a rotating cup-like abrading tool, supporting said abrading tool for tilting movement about a second fixed axis normal to and intersecting the axis of rotation of the article, and simultaneously controlling said tilting movement and the rotation of said article about said first axis in such a manner that the said tool will assume a given angle of tilt in one major meridian of said article and will assume another given angle of tilt in another major meridian of said article as said tool and article are being rotated.

10. The method of generating compound surface curvatures on an article comprising rotating said article about a first axis andwhile in engagement with a rotating cup-like abrading tool, supporting said abrading tool for tilting movement about a second fixed axis normal to and intersecting the axisof rotation of the article, simultaneously controlling said tilting movement .and the rotation of said article about said first axis in such a manner that the said tool will assume a given angle of tilt in one major meridian of said article and will assume another given angle of tilt in another major meridian of said article as said tool and article are being rotated, andvarying the extent of the angle of tilt in said major meridians according to the related curvatures desired.

11. The method of generating compound surface curvatures on an article comprising rotating said article about a first axis and while in engagement with a rotating cup-like abrading tool, supporting said abrading tool for tilting movement about a second fixed axis normal to and interconnecting the axis of rotation of the article, simultaneously controlling said tilting movement and the rotation of said article about said first axis in such a manner that the said tool will assume a given angle of tilt in one major meridian of said article and will assume another given angle of tilt in another major meridian of said article as said tool and article are being rotated, and causing said article and tool to move a controlled amount toward each other during said abrading. v

12. In a device of the character described the combination of'a rotatable cupped abrading tool, means for supporting a lens blank for rotation about an axis passing through said blank, means for moving the blank and tool axially into engagement with, each other, and means for automatically tilting said'tool and blank relative to each other to different given angular positions at given diiferent major meridians 01 said blank, said tilting action occurring about a fixed axis normal to and intersecting said first axis, and said fixed axis traversing said tool at a point laterally of the axis of rotation of said tool.

13. In a device of the character described the combination of a rotatable cupped abrading tool,

. means for supporting a lens blank for rotation about an axis passing through said blank, means said fixed axis traversing the tool at a point laterally of the axis of rotation of said tool, and means for controlling the extent of movement of said tool and, lens blank toward each other during said abrading.

14. In a device of the character described the combination of a rotatable cupped abrading tool, means for supporting work for engagement with the tool, said abrading tool being pivotally supported to be moved relative to the work,'means for moving said tool on its pivot relative to the work so as to simultaneously generate curves of two difierent radii one in each of the major meridians oi the work and means functioning cooperatively with said last named means for cushioning the movement of the tool relative to the work.

15. In a device of the character described the combination of a rotatable cupped abrading tool, means for supporting work for engagement with the tool, said means being adjustable in a direction toward and away from the tool, said abrading tool being pivotally supported to'be moved relative to the work, means for moving said tool on its pivot relative to the work so as to simultaneously generate curves of two difierent radii one in each of the major meridians of the work and means acting in opposition to said last named 7 relative to the work.

means for cushioning the movement of the tool CHARLES A. ELLIS. LAWRENCE A. SEVERY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 990,524 Chalmers et a1 Apr. 25, 1911 1,901,181 McCabe Mar. 14, 1933 1,448,239 Schuessler Mar. 13, 1923 1,221,858 Hollands Apr. 10, 1917 881,168 Wall et a1. Mar. 10, 1908 1,332,074 Simpson Feb. 24, 1920 1,415,613 Simpson May 9, 1922 2,286,361 Goddu June 16, 1942 1,003,816 Scoville Sept. 19, 1911 1,140,483 Rogers May 25, 1915 968,699 Schmidt Aug. 30, 1910 2,005,718 Desenberg June 25, 1935 Re. 14,751 Brockbank Nov. 18, 1919 1,286,032 Lalsne Nov. 26, 1918 1,401,832 Taylor Dec. 27, 1921 2,352,146 Desenberg June 20, 1944

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