US3277612A - Lens aligning and blocking apparatus - Google Patents

Description

Oct. 11, 1966 o, BRANDT 3,277,612

LENS ALIGNING AND BLOCKING APPARATUS Filed Feb. 28, 1964 52 4 INVENTOR m MILO o. BRANDT ATTORNEY United States Patent 3,277,612 LENS ALIGNING AND BLOCKING APPARATUS Milo O. Brandt, Williamsville, N.Y., assignor to American Optical Company, Southbridge, Mass., a voluntary association of Massachusetts Filed Feb. 28, 1964, Ser. No. 348,013 7 Claims. (Cl. 51-277) This invention relates to apparatus for aligning and blocking articles such as lens blanks.

An object of the invention is to provide for the aligning and blocking of lens blanks in an economical, simple and single operation substantially without introducing parallax error and to provide with each operation a fresh, previously unused removable block for adapting a lens blank to finishing machinery.

Apparatus embodying principles of the present invention is described in the following detailed description which is accompanied by a drawing in which FIG. 1 illustrates in perspective an exemplary lens blank having a block thereon produced by the use of apparatus of this invention;

FIG. 2 is a cross section of the lens blank and block illustrating use of the block in processing operations performed on said lens blank;

FIG. 3 is a plan view of one part of an embodiment of this invention;

FIG. 4 is an illustration in perspective of another part;

FIG. 5 is a fragmentary cross-section taken through both such parts of the apparatus with components of each thereof illustrated in an interrelated position of use for aligning a lens blank;

FIG. 6 is a partial plan view of the apparatus combination in FIG. 5 taken generally along line 6-6 looking in the direction indicated by the arrows; and

FIG. 7 is a longitudinal section view taken generally along line 7-7 of FIG. 3 illustrating one part of the apparatus in inverted position for forming the block upon a pre-aligned lens blank.

Referring now to FIG. 1, there is shown a lens blank L having block B molded in prealigned attached relationship upon one side thereof. In this illustration, block B is shown as including tang 10 arranged to be received coaxially in an exemplary adaptor 12 therefore (see FIG. 2). Block B further includes shoulder portion 14 arranged to abut adaptor 12 to assure proper axial spacing of the block in the adaptor and lugs 16 on diametrically opposed sides of tank 10 arranged to key into adaptor 12 for assuring proper radial orientation of block B in the adaptor. It should be understood that the foregoing structural characteristics of block B have been selected for purposes of illustration only and it will become apparent that the apparatus of this invention can be designed to provide a wide variety of block configurations suitable for use in various other types of adaptors, not shown.

Lens blank L can be supported by block B on various machines during the process of its manufacture such as, for example, upon the lens supporting spindle of a conventional lens edging machine. For purposes of illustration only, a portion of such a spindle 18 having adaptor 12 thereon is shown in FIG. 2. In this arrangement, block B is received within adaptor 12 and held therein by clamping pad 20 on auxiliary spindle 22 which is selectively retractable to permit insertion and removal of a blocked lens blank.

In a lens edge finishing operation, the lens blank is rotated by spindle 18 about a preselected center usually referred to as the geometrical center of the blank while, during such rotation, it is held in a fixed position of radial orientation on the spindle relative to an established transice verse meridian of the blank which is commonly referred to as the meridian. This meridian and the geometrical center are conventionally marked upon lens blanks with an ink or the like as illustrated in FIG. 6 by reference numerals 24 and 26 respectively. Accordingly, in the illustrated embodiment of this invention, block B is formed upon lens blank L with the axis of intended rotation of tank 10 extending through center mark 24 and with lugs 16 aligned with meridian markings 26. It should be understood, however, that the present invention does not preclude the blocking of lens blanks for the performance of other manufacturing operations thereon such as surface finishing wherein other but similar center and meridional markings such as the optical center and cylinder meridian of a lens blank might be blocked to.

A block molded upon a lens blank in accordance with the concept of this invention must be sufficiently strong to withstand stresses exerted thereon during a lens finishing operation and it must not be significantly weakened by heat which might be generated during the finishing operation but should have such a low melting point as to permit both convenient molding of the block on the lens blank and removal thereof after completion of the lens finishing operation.

A presently preferred block forming material adapted to conform to the above requirements would be a metallic alloy such as, for example, one known commercially as Cerro-low or Cerro-bend manufactured and sold by Cerro de Pasco Company, which liquefy at temperatures between 117 and 156 Fahrenheit and which have very low coefficients of expansion.

In the illustrated embodiment of the invention, one part of the apparatus comprises lens chuck 28 (see FIGS. 3, 5 and 7) having a cast or otherwise preformed elongated rigid body member 30. Attached to one end of member 30 by connecting screws 32 and extending forwardly of said one end, is fixture 34 formed of rigid transparent plastic material or the like having centrally disposed opening 36 extending therethrough. Opening 36 is of a diameter considerably smaller than that of the usual lens blank to be aligned and blocked.

There is press-fitted and/or cemented for security of fixed positionment coaxially in opening 36, mold 3 8 which includes rigid annular section 40 and stiflly resilient member 42 formed of a relatively hard but still slightly resilient and substantially non-abrasive rubber material or the like cemented to section 40. Coaxial openings through section 40 and member 42 together provide mold cavity 44 having opposite open ends.

Mold cavity 44 has a shape corresponding to that described hereinabove with relation to the configuration of block B wherein the opening in section 40 forms tang 10 and lugs 16 of block B while the opening in member 42 forms shoulder portion 14 of the block when a moldable block forming material is entered into cavity 44. Notches 46 (see FIG. 5) in section 40 are provided to form lugs 16 on block B.

As it can be seen more readily in FIGS. 5 and 7, member 42 of mold 38 also serves as resilient non-abrasive supporting means against which one side of lens blank L can be placed, without danger of becoming scratched or otherwise damaged, for alignment and blocking in chuck 28. Lens blank L, when pressed against member 42 closes the adjacent open end of cavity 44 and thus, member 42 resiliently forms a seal around the cavity opening.

For releasably clamping lens blank L against member 44, lever 48 is pivotally mounted on extensions 50 of body member 30 for movement of one of its ends toward and away from mold 38. At that end of lever 48, are a pair of spaced lens blank engaging fingers 52 extending toward mold 38 normally in approximately centered relation thereover. Fingers 52 (FIGS. 5 and 7) are preferably formed of a rigid plastic or a similar material which is non-abrasive to glass. In the embodiment illustrated, they comprise integral depending portions of annular member 54 which member is pivotally connected to lever 48 by diametrically opposed pivot pins 56. Fingers 52 are chisel shaped or tapered in one direction as shown in FIG. 7. Each thus engages and makes line or at least point contact with the facing side of lens blank L. As a result of member 54 being pivotable about the common axis of pins 56 and the fingers each being tapered along a line normal to that axis, the fingers will universally each assume direct contact with the lens blank when pressed thereagainst regardless of variations in thickness of the blank such as, for example, might result from prism having been introduced into the blank during previous surfacing thereof.

Lever 48 is biased resiliently and releasably into lens blank engagement by spring 58 (FIG. 7). Stop tab 59 struck from lever 48, contacts body member 30 to prevent the lens engaging end of lever 48 from pressing against member 42 of mold 3-8 when a lens blank is not in place thereon. Lever 48 extends from mold 38 beyond its pivotal connection to body member 3!} sufiiciently to permit convenient hand gripping of that extended portion thereof together with the adjacent portion of body member 30 so that, with a squeezing action, its forward end can be conveniently lifted away from mold 38 to permit insertion and removal of lens blanks. With lever 48 completely released, spring 58 will provide a secure clamping force upon lens blank L.

Referring more particularly to FIGS. 5 and 7, it can be seen that the rigid section 49 of mold 38 is provided with an internal passage 60 and elbow fittings 62 and 64 through which a fluid temperature conditioning medium supplied through one of tubes 66 or 68 and returned through the other tube can be circulated through passage 68. A medium so circulated would condition the temperature of mold 38 around its cavity. Normally the medium would be a coolant such as cool or cold water when it is desired to accelerate hardening of block forming medium such as mentioned above. If, however, a blocking medium is selected which requires relatively high temperatures for hardening, the circulated medium might, for example, be hot water or steam.

For purposes of aligning lens blank L relative to cavity 44 in mold 38, opaque fiduci-al marks 70' (see FIGS. 3 and 6) are provided on transparent fixture 34 in alignment with notches 46 in the mold. Thus, as it can best be seen in FIG. 6, meridional markings 26 on lens blank L can be oriented into superimposed relationship of alignment with marks 70 by rotational adjustment of blank L while the blank is clamped against mold 38. In FIG. 6, the lens markings are intentionally shown as not being aligned with those on chuck 28 to permit illustration of both such markings in the same view. Some or all of the clam-ping force on lens blank L can be released during lens blank alignment by manipulation of lever 48.

This alignment of lens blank L is accomplished by looking through marginal portions of the blank and to facilitate same, chuck 2-8 is intended to be placed upon transparent table 72 (see FIG. 4) which is illuminated by lamp 74 disposed therebeneath in table supporting structure 76. Table 72 is pivotally mounted by pivot pins 78 and 88 upon structure 76 to permit, by selective tilting thereof, its convenient use from either a standing or sitting position.

One or both sides of table 72 are preferably sand blasted, etched or otherwise treated to diffuse and thus reduce glare of light projected therethrough. With the forward portion of chuck 28 placed against table 72 substantially as shown in FIG. 5, light from lamp 74 passes through table 72, trnasparent fixture 34 and lens blank L to illuminate fiducial marks 70 and the meridional markings 26 on blank L thus facilitating alignment of such marks one relative to the other even though lens blank L might be formed of a shaded or colored material rather than the more common clear glass or plastic material.

With respect to achieving alignment of center mark 24 on lens blank L over mold cavity 44, table 72 is provided with spring loaded clear plastic generally cylindrical plunger 82 extending the'rethrough. The proximal end of plunger 82 is generally pointed as the frustrum of a cone with an opaque or semi-transparent fiducial dot 84 painted or otherwise provided centrally thereon.

Plunger 82 is mounted in bushing 86 for axial movement therein within. limits. Bushing 86 extends through table 72 and is press fitted or otherwise fixedly secured therein. Spring 88 biases plunger 82 in a direction away from the top of table 72 and stop ring 90 fitted to plunger 82 adjacent its distal end prevents axial displacement of the plunger from bushing 86 and holds spring 88 under slight compression.

Section 92 of plunger 82 beneath the conical portion thereof is cylindrical in shape and of such diametral size as to fit intimately but freely into mold cavity 44 so that when entered into the cavity, fiducial dot 84 will be accurately centered upon the axis of the cavity and provide reference means relative to which center mark 24 on lens blank L can be accurately aligned upon such axis.

In FIG. 5 it can be seen that alignment of center mark 24 is accomplished without parallax error by placing chuck 28 over plunger 82 and causing section 92 thereof to enter mold cavity 44 through the open end thereof opposite 50 that closed by lens blank L. In so doing, the proximal end of plunger 82 is caused to directly engage the side of lens blank L disposed inwardly of cavity 44 and thus place fiducial dot 84 against that side of the blank. Lens chuck 28 is moved into such proximity with table 72 as to depress plunger 82 at least slightly causing spring 88 to compress and force the proximal end of plunger 82 firmly against lens blank L. Plunger 82 being depressiible axially as described will, accordingly, automatically adjust so as to seat firmly endwise against any lens blank placed in chuck 28 regardless of the particular curvature provided on the side of the blank intended to be so engaged.

Legs 94 on the under side of transparent block 34 are provided to limit the extent of movement of chuck 28 toward table 72 so as to prevent section 92 of plunger 82 from, at any time, engaging bushing 86 which could cause displacement of lens blank L in chuck 28 should movement of chuck 28 toward table 72 be thereafter continued to too great an extent. Legs 94 also function to position chuck 28 squarely relative to table 72 and prevent possible binding of plunger 82 in mold cavity 44. They may also be adjusted so the plane of the mold cavity is truly parallel to that of table 72.

With chuck 28 and plunger 82 inter-related as shown in FIG. 5, alignment of center mark 24 on lens blank L relative to fiducial dot 84 can be effected by sliding adjust-ment of lens blank L in chuck 28. Mark 24 and dot 84 are viewed through the central opening in annular member 54 and light from lamp 74 is transmitted mainly by internal reflection through plunger 82 and thence through lens blank L to illuminate and render mark 24 and dot 84 readily perceivable.

Alignment of both the center and meridinal markings 24 and 26 respectively on lens blank L are ordinarily made at the same time with chuck 28 and plunger 82 inter-related as shown in FIG. 5.

Once blank L is aligned and firmly clamped in chuck 28, the chuck is lifted from plunger 82 and inverted substantially as shown in FIG. 7 whereupon a moldable block forming material is dispensed into cavity 44 through the open end opposite to the end thereof which is closed by lens blank L. Accordingly, the block forming material will, in filling out cavity 44, flow against and become attached to lens blank L as illustrated in FIG. 7.

Although, as here illustrated, the resultant lens block B is adhered directly to lens blank L it should be understood that the blank could be surface coated with a material such as polyvinyl chloride or the like which serves to insure better adherence of the block to the lens blank but can be conveniently peeled from the finished lens after removal of the block. Wherever block B is referred to herein as being attached to the lens blank it is intended to mean either directly thereto as illustrated or to a surface coating medium on the blank, not shown.

While the block forming medium can be ladled or otherwise poured into mold 38, a dispenser 96 for block forming material can be arranged upon structure 76 in the manner illustrated in FIG. 4 for convenience in filling mold cavity 44 by placement of the receiving open end of the cavity adjacent outlet nozzle 98 of the dispenser as illustrated in FIG. 7. Such a dispenser is shown and described in assignees copending application Serial No. 260,476, filed February 25, 1963.

Once the molded material has hardened sufiiciently to form the block, lever 48 is pivoted to release lens blank L and block B is lifted from mold 38 together with the lens blank. The blocked lens blank can then be adapted directly to lens finishing machinery as described above.

While circulation of a medium through mold 38 will accelerate hardening of the block forming material, one may if desired provide a pair of lens chucks 28 for alternate use so as to allow for more than adequate hardening time for the block forming material in one chuck during performance of a lens aligning and mold filling operation using the other chuck.

It can be seen that a fresh and previously unused block is formed with each lens blocking operation and upon completion of a lens blank finishing operation utilizing the block, it can be released and removed from the lens blank by pinching shouldered portion 14 thereof or by melting.

Markings on the lens blank are usually preserved during the operations of blocking, lens finishing and removal of the block so that they can be subsequently used to facilitate proper alignment of the finished lens in a spectacle frame or the like.

I claim:

1. Lens aligning and blocking apparatus comprising a mold having a block forming cavity therein, said cavity having oppositely disposed open ends, means for releasably clamping a lens blank against one of said open ends of said cavity to close such end, aligning means removably insertable into said cavity through the end thereof 0pposite to said closed one end, said aligning means including a plunger of generally rod-like configuration adapted for endwise engagement with said len blank and formed of light-conducting material having a substantially opaque fiducial mark at the lens blank engaging end thereof relative to which said lens blank may be aligned in predetermined relationship to said cavity whereby, following such alignment of said lens blank and subsequent removal of said aligning means from said cavity, a moldable material may be introduced into said cavity so as to form a block on said lens blank in prealigned relationship therewith.

2. The apparatus of claim 1 in which means is urovided for illuminating the end of said plunger opposite to said one end thereof to cause light to enter and be conducted through the plunger and lens blank for facilitating alignment of said lens blank relative to said fiducial mark.

3. The apparatus of claim 1 in which said fiducial mark is substantially in the form of a dot on said one end of said plunger by means of which a preselected point on said lens blank may be aligned relative to an axis through said block-forming cavity in said mold.

4. The apparatus of claim 3 in which means having at least one fiducial line thereon extends laterally from said mold, said means being in fixed relationship with said mold and said fiducial line being disposed in predetermined aligned relationship with said block-forming cavity for use in aligning a preselected transverse meridian of said lens blank in a predetermined condition of radial alignment relative to said block-forming cavity.

5. The apparatus of claim 4 in which both said plunger and means extending laterally from said mold are formed of light-conducting material and means is provided for directing light simultaneously through said plunger and through said laterally extending means for illuminating marginal and central portions of said lens blank to facilitate said axial and radial alignment of the blank relative to said mold cavity.

6. The apparatus of claim 5 in which said plunger is axially depressibly mounted in a table formed of lightconducting material, said table being mounted on a sup-- porting structure therefor and said means for directing light through said plunger and laterally extending means includes a lamp disposed in said supporting structure beneath said table.

7. The apparatus of claim 1 in which said mold is fixed to one end of an elongated rigid supporting member and said means for clamping the lens blank against said mold comprises a lever pivotally connected to said member be tween opposite ends thereof, said lever having one of its ends disposed over said mold with means thereon adapted to engage said lens blank and being extended from said one end beyond said pivotal connection to an opposite end adapted to be gripped together with said body member for releasing its engagement with said lens blank and spring means normally biasing said one end of said lever toward said lens blank for clamping the blank against said mold.

References Cited by the Examiner UNITED STATES PATENTS 1,581,883 4/1926 Steinle 33-28 2,660,011 11/1953 Bernheim et al 51-277 2,982,061 5/ 1961 Dillon 51277 3,049,766 8/ 1962 Buckminster 22-58' 3,118,198 1/1964 Prunier 51277 FOREIGN PATENTS 800,725 7/ 1949 Germany.

ROBERT C. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

J. A. MATHEWS, Assistant Examiner.

Claims (1)

1. LENS ALIGNING AND BLOCKING APPARATUS COMPRISING A MOLD HAVING A BLOCK FORMING CAVITY THEREIN, SAID CAVITY HAVING OPPOSITELY DISPOSED OPEN ENDS, MEANS FOR RELEASABLY CLAMPING A LENS BLANK AGAINST ONE OF SAID OPEN ENDS OF SAID CAVITY TO CLOSE SUCH END, ALIGNING MEANS REMOVABLY INSERTABLE INTO SAID CAVITY THROUGH THE END THEREOF OPPOSITE TO SAID CLOSED ONE END, SAID ALIGNING MEANS INCLUDING A PLUNGER OF GENERALLY ROD-LIKE CONFIGUATION ADAPTED FOR ENDWISE ENGAGEMENT WITH SAID LENS BLANK AND FORMED OF LIGHT-CONDUCTING MATERIAL HAVING A SUBSTANTIALLY OPAQUE FIDUCIAL MARK AT THE LENS BLANK ENGAGING END THEREOF RELATIVE TO WHICH SAID LENS BLANK MAY BE ALIGNED IN PREDETERMINED RELATIONSHIP TO SAID CAVITY WHEREBY, FOLLOWING SUCH ALIGNMENT OF SAID LENS BLANK AND SUBSEQUENT REMOVAL OF SAID ALIGNING MEANS FROM SAID CAVITY, A MOLDABLE MATERIAL MAY BE INTRODUCED INTO SAID CAVITY SO AS TO FORM A BLOCK ON SAID LENS BLANK TO PREALIGNED RELATIONSHIP THEREWITH.

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