US2321383A

US2321383A - Contour forming apparatus

Info

Publication number: US2321383A
Application number: US358887A
Authority: US
Inventors: Worthy C Harper
Original assignee: American Optical Corp
Current assignee: American Optical Corp
Priority date: 1940-09-28
Filing date: 1940-09-28
Publication date: 1943-06-08
Anticipated expiration: 1960-06-08

Description

June 8, 1943. w. HARPER l 2,321,383

CONTOUR FORMING APPARATUS Filed Sept. 28, 1940 Z'Shee'c's--Sl'xe'c 1 I NV EN TOR.

Je 8, 1943. v w C, HARPER 2,321,383

coNTQUR FORMING APPARATUSv Filed Sept. 28, 1940 2 Sheets-Sheet 2 INVENTOR. WORTHY C. HHK/EK ATTO NEY Patented June 8, 1943 CONTOUR FORMING APPARATUS Worthy C. Harper,V Caldwell, Ohio, assignor to American Optical Company,

Southbridge,

Mass., a voluntary association of Massachusetts Application september z8, 1940, serial No. 358,887

(C1. 51-1on 7 Claims.

This invention relates to newand improved means for forming the contour of articles and has particular reference to apparatus adapted to form the contour of lenses or like articles.

This application contains Subj ect matter which is common to a co-pending application Serial No. 358,888.

A principal object of the present invention is the provision of novel and improved means for forming the contour of articles in a much shorter time than ordinarily required.

Another object of the invention is the provision of means which will automatically advance the article to be formed only as fast as the article is ground to desired size and shape.

Another object is the provision of means for automatically stopping the rotation of the article when a high spot on the article is engaging the grinding wheel and automatically restarting the rotation when the high spot has been removed.

Another object of the invention comprises new and improved means for forming the contour of articles, which comprises means'for rotating the article against a rotating grinding wheel and means for controlling the rotation of the article i so that when a high spot on the contour of the article is in Contact with the wheel the rotation of the article is automatically stopped and remains stationary until the high spot is ground off and then contact is again automatically madet and the article begins to rotate until another high spot is encountered and that is then ground olf and this is continued throughout the full revolution of the lens.

Another object of the invention resides in the provision of a device of the character set forth wherein the rotation of the article is controlled by electricalcontacts. Y

Another object of the invention is the provision of an improved device which may easily and quickly be changed to'form or grind articles of any one of a number of dierent shapes as Well as improved adjustable means for determining the size of the article produced.

Another object of the invention is the provision of improved means for supporting the article to be formed and driving and controlling the said supporting means.

Another object of the invention is the provision of an improved device which will grind an article to the desired contour shape and size in -one complete revolution.

Other objects and advantages of the invention will be 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 and arrangement of kparts without departing from the spirit of the invention as expressed in the accompanying claims. I, therefore, do not wish to be limited to the exact details of constructions, and arrangement of parts shown and described as they have been given only by way of illustration.

Referring to the drawings:

Fig. I is a perspective view of a lens edging machine embodying the. invention;

Fig. II is a partial side View of the machine shown in Fig. I;

Fig. III is a sectional view taken on line III- III of Figure I looking in the direction of the arrows; and

Fig. IV is a side view of the grinding wheel and lens being ground;

Prior art lens grinding machine and processes have had many difficulties and one of the main difculties was that the lens 'in many instances had high or hard spots on its periphery so that when it wasedged to contour shape eitherv certain parts of the lens would not be ground down to the desired sizeor in an eiort to grind these hard spots down the adjacent portions of the lens would be ground below the desired contour. This was true because in some structures a stop mechanismwas arranged in connection with the former so that when any one point on the periphery of the lens was ground to contour shape this stop mechanism was actuated by the former and the grinding stopped. This meant that there could be high spots remaining and yet have the machine sto-p. In some instances the machines were so set as to continue grinding with both the lens andA wheel turning a certain specified number of times after one portion of the lens had been'ground to the desired contour. .This meantthat the softer portions of the lens were liable to be ground beyond the desired contour.

The apparatus and process of this invention provides means and method whereby each point of theperipheryis ground to the desired contour before the lens is turned to present a new point and preferably one revolution only of the lens is made. The difficulties of the prior art are thus obviated and accurate and quick edge grinding of lenses is-made possible.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several'views,

the device embodying the invention comprises a grinding wheel I rotatably mounted on a base 2 through a pulley 3 and a lens holding structure 6 supporting lens I0 and being swingable toward and away from the wheel as well as having provision for rotating the lens. The method of the invention includes the steps of rotating the wheel, swinging the lens holding structure so as to engage the lens and wheel until the lens is down to size at the engaging point and thereafter rotate the lens and successively bring each point of the periphery down to size. The apparatus is so arranged and the method so carried out that the lens is rotated only when its peripheral portion nearest or in contact with the wheel is down to size.

On the base 2 is mounted a motor 4 and support 5 on which is mounted the Vlens supporting carriage `I. This carriage 6 Vis pivotally mounted, for movement toward and away from the wheel, on the support 5 through pins 1 which extend into bearing holes 8 in the uprights 9.

The lens or other article to be ground I8 is held in desired related position with the lens supporting carriage by Ymeans of the pads II on the shafts I2 and I3 and is adapted to be rotated by rotation of the shafts I 2 and I 3, through the gears I5, I8 and I9 carried by the shaft I1, and gears 2D and 2I, by the interima-rking of the gear I8 with the worm gear I4. This gear I4 is mounted on the shaft I5 -extending from the motor 4. The worm gear I4 drives the gear I5 which rotates the shaft I1 and gears I8 and I9. Rotation of the gears IIB and I9 journaled on the shaft I1 drives the gears 29 and 2|.to simultaneously rotate the shafts I.2 and I3 and cause the lens Orother article to be ground I4 to rotate. The shaft I3 may be driven by the shaft I2 by means of clutch action through the lens I9, or pads II, or both, but is preferably driven through the shaft Hand .gears I8 and 28 so as Vto be driven simultaneously ,with the shaft I2.V

The former 25, .Which..has the peripheral contour desired on the finished Varticle is positioned on the shaft I3 and held thereon in position by pin members 21, as illustrated:` in Fig. III, and is adapted to contact the former shoe 28 when the contour of the article is .being ground.

The electrical circuit comprises a pair of wires extending `from a plugconnection 23 each to one of the

contacts

41 and 48. Wire 29 extends directly to the holder 30 of Contact 48 and wire 22 extends to rheostat 51, to motor 4,.and thence to the holder of contact 41 through wire 24. Thus, upon making contact between

contacts

41 and 48, the circuit is closed and the motor 4 is operated in accordance with the adjustment of the rheostat 51, thereby rotating the lens. The

contacts

41 and 48 are, however, so spaced and adjusted as to meet, when the device is in operation, only when a point on the periphery of the lens is ground down to size as defined by the former 2B.

The lens I9, through lens holding carriage 8, is resiliently urged towards the grinding wheel I by the spring 3l which has one end connected to a post 32 on the lens holding carriage 6 and its other end secured to a post 33 on the bearing 34 for the grinding wheel, so as to urge the carriages about its pivot 1.

The former shoe contact runit is illustrated in Fig. II and comprises contact members 58 and 28, adjusting and supporting

members

35 and 45 and locking

members

54 and 38.

' This con-tact shoe unit is provided so that adjustment may be made in the distance between the contact points 41 and 43 and it will be seen that adjustment of this distance varies the extent of `the grinding of the lens since the lens is so supported that it remains in one position without rotation until the

contacts

41 and 48 moet and complete the circuit, which starts the motor, which in turn rotates the lens. Normally the

contacts

41 and 48 tend to separate -either under the action of gravity or a spring such as shown at 23a, so that the contact holder 28 rests against the edge of the former 25 when in position of operation. Movement of this former toward the contact unit, as brought about by the grinding of the lens I8, moves the holder 28 about its pivot 28h and so as to eventually cause the

contacts

41 and 48 to meet. The distance between these contacts may be varied by adjustment of a contact screw 49 or by the action 0f a cam member 42 upon the upright 35 through its extension 33 and about its pivot in the supports 36.

This upright arm 35 may or may not have .i brace bar 31, as desired. The arm 35 'has an extension 38 at its lower end. At its upper end the bar 35 is pivotally connected to the member 59 whereby the whole unit may be pivoted towards or away from the former 26 through movement of the cam member 42 by movement of a pointer 39 over an indicating scale 48 which has calibrations 4I which represent sizes of the ar ticle to be ground. The pointer 39 is set at the desired size position and the contacts are thereby separated a distance sufficient to permit the lens to be ground to the size indicated by said setting before the contacts meet.

The member 42 to which the pointer 39 is se cured has a cam-like upper surface so that movement of the pointer 39 raises or lowers the arm 38. and the Contact shoe 28 moves towards or away from the `former 25 thus allowing the lens III to be ground to desired size.

A support is provided for contact holder 5t through a projection .44 on the base 2 to which is' pivoted the lever 45. This lever is pivotallv secured at its upper end to the arm 46 which in turn is secured to the mem-ber 59. Arm 4S is rigidly secured to the support member 59 so that lthis member may, under the action of cam 42 and arm 35, move about its pivot 50a to vary the distance between the contacts.

IOn the foi-mer shoe member 28 is secured the electric contacting point 41 and on the member 50 is secured ythe electric contacting point 48 in line with the point 41 with these contacts adapted to complete the circuit when in contact with each other. The point 48 is adjustable in a direction towards or away from the point 41 by means of the screw 49 which extends through the member 5t and on the end of which the contact point 48 is secured. Thus by turning the screw member 49 the points 41 and 43 may be brought closer together or moved farther apart. This allows the points to be adjusted to compensate for wear or to achieve the desired rela vtive positions of the contacts with respect to each other.

Locking mechanism is provided in that the member 58 has an extension 30 with a catch 52 and the member 28 has an extension 53 with a latch member 54 pivoted at its upper end. The member 54 has a handle 55 land latch portion 58. By securing the 'latch 56 in the catch 52 the contact points 41 and 48 may be locked in contacting operative position thus causing continuous rotation of the lens holder until the catch 52 and latch 5S are disconnected.

Adjacent the motor 4 is a rheostat 51 adapted to be adjusted to cause the motor and therefore the lens to run at desired speed.

The former 26 as it rotates engages the former shoe member 28 thus guiding the lens and causing it to be ground to desired contour and to the size indicated by the pointer 39 on the indicator 46 and as the lens is rotated if a high spot therein is reached the rotation of the lens is stopped and urged against the wheel until the high spot is ground olic after which the rotation of the lens is resumed until another high spot is encountered. When this happens the rotation of the lens is again stopped until the high spot is removed and this procedure continues until the entire contour of the lens has been ground to desired shape and size.

It will readily be understood that a single former of the desired contour shape may be used for lenses of various sizes since the size adjustment is embodied in the contact unit.

The operation of the device is as follows:

A lens or other article Ill which is to have its contour ground to desired size and shape is placed in edge to edge relation with the grinding wheel I and secured by the pads II on the shafts I2 and I3.

The pointer 39 is then moved on the indicating scale 40 until it indicates the size desired on the nished article.

A former 26 is secured on the shaft 80. This former has its contour ofthe shape desired on the article to -be ground. It is to be noted that this former is removably secured to the shaft 86 and may be replaced by other formers of other shapes.

The plug 23 is secured to a source of electric current and the rheostat 51 is adjusted to cause the motor 4 to run at desired speed in order to rotate the shafts I2 and I3 and lens.

'Ihe grinding wheel I is the usual type lens grinding wheel 'and is mounted and rotated in the usual prior art manner through the pulley 3.

As the edge or contour of the lens I is being edged or ground the contacting

points

41 and 48 are separated causing only the grinding wheel to rotate and the rotation of the lens to stop until the edge of the lens has been ground to desired shape and size when the former 26, which is resiliently urged toward the former contact shoe by means of the spring 3|, causes the points 41 and 43 to contact to again start the motor 4 and thus cause the .rotation of the former 25 and lens III until another high spot on the edge of the lens encounters the grinding wheel I when the former 26 will again be forced away from the former shoe 28 causing the

points

41 and 48 to again separate, shutting off the power and stopping the motor 4 thus allowing the high spot on the lens I6 to be ground until the same has been removed at which time the contact points 41 and 48 will again engage to cause further rotation of the lens I0. This operation is continued until the lens has been ground to desired contour and size.

With this apparatus and method it will be apparent that after a single rotation of the lens has been completed the entire contour of the lens will have been ground to desired contour and size. That is, only one complete rotation of the lens is required thus saving considerable time which was necessary with former devices of this character. Greater accuracy in grinding to exact dimensions throughout the periphery of the lens is made possible with the apparatus and method of this invention since in prior art structures the lens and wheel are both rotated continuously and automatically stopped when one portion of the lens periphery is down to size. The

Vapparatus and method of this invention is such .ing portions and 6I, fitted with

suitable bushings

62 and 63. l

As shown in Fig. III, the bearing 66 of the lens supporting carriageV 6 contains means for allowing lens II) to be placed in position, clamped and rotated.

Slidably mounted in bushing 62 in the bearing 6IJ is a partially hollow shaft 64 having a gear 2I pressed on at one end thereof, and slidably mounted in the hollow shaft 64 is a shaft I2, which has attached at` one end a pad holder 65 and pad II. The pad holder 65 is held in rigid relation with shaft I2 by a suitable pin 66. The shaft I2 has in internal threaded portion 61 connected with the threaded shaft 68 which extencls through the

hollow shaft

6,4 and is connected with a suitable hand wheel or the like 69 by means of a pin 10. The shaft I2 has a keyway 1I cut longitudinally in its outer surface so that when in connection with pin 12 set in the hollow shaft 64 causes both shafts to rotate, while allowing shaft I2 and pad holder 65 to be moved longitudinally of the bearing 62 by the action ofthe thread on shaft 68 upon the turning of the hand wheel 69. This movement moves the lensholding pads relative to each other and allows the lens IIJ to be placed, clamped and rotated in the proper position before the grinding wheel I. vvThe gear 2| and the pad holding assembly are held in place against the outer edge of the bearing 60 by means of a` clamp screw-13 and lock nut 14fwhich bear against a ball 15 set in the end of the threaded shaft 68. The screw 13 and lock nut 14 are held by an arm 16 attached to the bearing member 63 by screws 11V and 18. i Y

In the bearing 6! and bushing 63 is mounted means for removably locating and holding the Aformer 26 and means for rotating same inV unison with the lens or other article III.

These means consist of a shaft 86 placed in the bushing 63 which has a shouldered portion 82 bearing against one end of the bearing 6I, and has a gear 20 attached to the opposite end of the bearing by a set'screw 8l. Shaft BI) is thus held inthe bearing 6I. Set into the face of the shouldered portion 82 are locating pins 21. These pins 21 and the reduced projecting end of the shaft 8l) are adapted to locate, hold and rotate the former 26, the shaft I3, and the pad II through the action of the gear 20.

Referring to Fig. II it is to be understood that the support member 35 and its extension 33 kmay be held against the cam 42 by suitable weight or spring members so 'that when the cam drops away the arm 38 will follow.

From the above it will be seen that the apparatus and process set forth will automatically cause the article to advance as quickly as its contour is ground to desired shape and size and will automatically stop the rotation of the article when a -high spot on the larticle is engaging the grinding 4wheel and automatically res-tart the rotation of the article when the high spot has been removed and that I have provided simple, eiiicient and economical means and processes for accomplishing all of the objects of the invention.

Having described my invention, I claim:

l. In a grinding machine of the lclass described having a rotatable grinding wheel, a pivotal frame member operable to and fro in relation to the periphery of the grinding wheel, a rotatable member carried bythe pivotal frame having thereon a clamping device and a former, said clamping device and former being capable of simultaneous rotation -by a gear train, a gear train for rotating said clamping device and former, a contact set positioning mechanism located adjacent said former and having a pair of contacts adjustable to different positional relation with each other with one of said contact members operable by said former, a motor having a control rheostat therefor serially connected with said contact set and a source of energy, and drive means permanently connecting said motor to said gear train.

2. In a device of the class described a revoluble cutting wheel rotatably mounted on a frame, a pivotal frame adapted to be moved toward vand away from said cutting wheel, Work holding means rotatably mounted on said pivotal frame, a former rotatably mounted on said pivotal frame to have relative to and fro movement with said working holding means, switching means having a pair of contacts, one contact of 'said switching means having an insulation member thereon for engagementk with the peripheral edge of the former, the otherof said contacts having adjustment means therefor for adjustment in relation to the remaining contact, a rotatable electric motor connected to said 'switching means and a source of energy, a driving mechanism connected from said motor to engage the former and the work holder means to cause rotation of same when the former engages the.

insulation strip on the switching mechanism to operate the switching mechanism and energize the motor.

3. In a device of the class described having a cutting wheel rotatably mounted on a frame, a

pivotal frame adapted to be moved toward and away from said cutting wheel, work holding means and a former rotatably mounted on said pivotal frame, switching means having a pair of contacts, one of said switching means having an insulation member thereon for engagement with the peripheral edge of the former, a rotatable electric motor circuitously connected to said switching means and a source of energy, a driving mechanism connected from said rotatable motor to rotate the former and the work holding means to cause rotation of same when the former engages the insulation strip on the switching mechanism to operate the switching mechanism and energize the motor.

4. In a grinding machine of the class described having a rotatable grinding wheel, a pivotal frame member operable toward and away from the grinding wheel, a rotatable member carried by the pivotal framehaving thereon a clamping device and aformer, a gear train, Said clamping device and former being capable of simultaneous 'rotation by said gear train, a contact set positioning mechanism located adjacent said former and having a pair of contacts adjustable to diierent positional relation with each other with one of said contact members operable by said former, a motor carried by said frame member and electrically connected with said contact set and a source of energy, and mechanical means permanently and operablyconnecting said motor to said gear train.

5. In a grinding machine of the class described having a rotatable grinding wheel, a pivotal frame member operable to and fro in relation to the periphery of the grinding wheel, a rotatable member carried by the pivotal frame having thereon a clamping device and a former, a gear train, said clamping device and former being connected with and capable of Vsimultaneous rotation by said gear train, a contact set positioning mechanism located adjacent said former and having a pair of contacts independently adjustable relative to each other with one of said contact members operable by said former, a motor carried by said frame member and having a control rheostat therefor serially connected with said contact set and a source of energy, and drive means permanently connecting said motor to said gear train, said contact set positioning means being adjustable for causing relative movement between the contact set and the former to provide adjustment therebetween for controlling the motor operating interval.

6. A grinding machine of the class described having a rotatable grinding wheel, a lens holding device and a former rotatable simultaneously with one another and movable toward and away from the grinding wheel, a contact set positioning means disposed adjacent said former having Contact portions independently adjustable relative to each other for partially controlling the time interval required for making substantially one revolution of the former, a motor carried by the lens holding device circuitously connected with said contact set and a source of energy, and drive means permanently connecting said motor to rotate the former and the lens holding device.

'7. In a grinding machine of the class described having a rotatable grinding wheel, a lens holding device for holding a lens to be ground by said grinding Wheel, means operable to automatically move the lens holding device toward said grinding wheel, last said means including a gear train to rotate said lens holding device, revoluble motor means to operate said gear train, a former disposed to rotate simultaneously with said lens holding device, a contact set spaced from said former and operable thereby, a contact set positioning means carrying said contact set and being adjustable for relative movement between the contact set and the former to provide adjustment therebetween for controlling the motor operating interval, and an insulating portion intermediate said former and said contact set to electrically insulate said former from said contact set.

WORTHY C. HARPER.