US3389508A - Cylinder grinder - Google Patents

Description

June 25, 1968 J. M. SUDDARTH ET AL 3,389,508

CYLINDER GRINDER Filed July 1, 1964 a Sheets-Sheet 1 i 322.. I 6 l J l llfllllll mvmvrons JACK M. SUDDARTH D L. GRAY AgRNEY June 25, 1968 J- M. SUDDARTH ET AL 3,389,508

CYLINDER GR INDER Filed July 1, 1964 5 Sheets-Sheet 2 June 25, 1968 M. S'UDDARTH ET AL 3,389,508

CYLINDER GRINDER Filed July 1, 1964 3 Sheets-Sheet 5 H2) ro 990- v I REG. 7 A

' \o-2o PSI Am T PRESSURE o a *3 SOURCE G "6 United States Patent a 6,389,508 i CYLINDER GRINDER JackM. .Suddarth, Fort Gibson, and Dolph L. Gray,

v Muskogee, Okla, assignors to Coburn Manufacturing Company, Inc., Muskogee, 0kla., a corporation of Oklahoma Filed July 1, 1964, Ser. No. 379,509

r 7 Claims. (CI. 51-60) This invention pertains generally to improvements in lens grinding'and polishing machines and, more particularly, relates toimprovement's in machines for polishing and lining the surfaces of cylindrical lens blanks. Machines of this type are comprised generally of a cylinder lap supportedon a platform in which there is introduced an irregular movement referred to in the art as a breakup movement, together with means for maintaining the lens in engagement with the moving lap. The prior art is well aware of mechanisms for producing break-up movements. 'For instance, the United States patent to Long, No. 2,159,620, and the United States patent to Lockhart, No. 2,168,843, disclose structures that are illustrative of this movement. In the invention described herein, the lens blank supporting structure receives an orbiting movement over the break-up movement of the lens lap. The above movements result in a variation of movement over the lap surface for the purpose of preventing the formation of aberrations, waves and distortions in the surface of the lens which will occur if the polishing process is not performed over the entire lap surface. i t

"A principal objective of this invention is to provide an automatic, pneumatic pressure mechanism providing a first pressure at the start of the finishing process and after a certain selected time, substantially increasing said start pressure. The result obtained from this process eliminates the serious breakage problem which often occurs in the polishing ofcylinder lenses.

The lens blank under discussion is secured at the lower end of an assembly which lifts and lowers the lens blank drive mechanism into and out of engagement with the lens back of the lens to be ground. This assembly can be termed as a head. The head, as it transmits its orbiting movement to the lens, receives both lateral and longitudinal stresses. It is an important objective of this invention to provide a supporting head of simple and durable construction for efiiciently assuming these stresses.

Another important objective of this invention is to p'rovide a mechanism for raising and lowering the head into and out of engagement with the lens blank in a manner whereby when the head is lowered to the proper position, it is automatically secured and will not retract except fora direct releasing movement by an operator.

A still further objective of this invention is to provide amachine of the type described wherein breakage is lessened by having a series of fluid pressures applied under the control of timing valves wherein polishing is begun at a reduced pressure and after a selected amount of time, increased pressure is automatically placed on the lens. This permits an operator to attend other equipment during the polishingoperation. In the prior art it was often necessary to have an operator remain at the machine for submitting the lens to increasing pressures as the polishing operation proceeded.

These and other objectives and advantages of the invention will be more fully understood upon a reading of the following specification taken in view of the attached drawings whereinr V FIGURE 1 is a diagrammatic (somewhat exaggerated) view of the lens and lap prior to polishing;

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[FIGURE 2 is a'front perspective view of the machine with portions broken away;

FIGURE 3 is an exploded perspective of the supporting head assembly and the handle lock assembly;

FIGURE 4 is an assembled side elevation of the handle lock assembly; 7

FIGURE 5 is a cross-sectional view of the handle lock assembly along the line 55 of FIGURE 4;

FIGURE 6 is a view similar to FIGURE 5 with the elements moved to their locking position;

FIGURE 7 is an assembled view of the supporting head assembly of FIGURE 3; and

FIGURE 8 is a schematic of the fluid pressure and timing valve apparatus. 7

Referring now to the drawings wherein a preferred embodiment of the invention is disclosed, like numerals are used to indicate like elements in the several views. The numeral 10 indicates generally the housing of a lens polishing machine. Attached to the front of the housing is a polishing bowl 12. The bowl is suitably equipped with means to provide a grinding slurry to the polishing area but these particular means form no part of the present invention.

The actual polishing and finishing of the lens takes place within the bowl 12. Disposed Within the bowl are a pair of lap supports '13 and 13a to which a pair of laps L are mounted. A brief referral to FIGURE 1 will disclose that prior to finishing a lens blank B, only the edge portions of the blank engage .the cylinder lap. When a downward pressure is exerted on the blank, lines of stress develop generally long the arrows 1 5. This invention is directed primarily to a means for automatically maintaining the pressures at a reduced level until the lines of stress are dispersed due to an initial removal of glass from the edges of the blank.

A break-up motion of the type heretofore described is imparted to the members 13 and 13a via the shafts 14 and 14a. At their outer ends the shafts are provided with handles and diaphragms for sealing the bowl apertures through which they extend. This last-mentioned arrangement facilitates removing the bowl when desired. It should be understood that the break-up movement occurs in a common plane without any rotational movement being transmitted to the laps.

Extending upwardly and somewhat forwardly of the housing 10 are a pair of standards 16 and 16a. Since the apparatus supported by standard 16 and all structure associated therewith is identical to that supported by 16a, only the standard 16 will be discussed in any detail. At its uppermost end, the standard 16 is horizontally journaled at 18 to receive the handle locking assembly 19 which is described in detail hereinafter. Forward of the journal is a bracket 20 having a vertical slideway 21 therethrough.

lidably received within the way 21 is the upper end of a lens blank supporting and driving assembly 26.

The drive assembly is supported by a rack 28 which is slidably received in slideway 21. The rack 28 is raised and lowered within the way via a pinion 30 which is operably connected to the handle lock assembly 19. The rack and pinion are utilized to raise and. lower the drive head assembly with respect to the lap L. A suitable opening between the journal 18 and the slideway 21 permits the pinion to mesh with the rack.

The handle assembly 19 is elfective to maintain the rack 28 at a fixed height regardless of longitudinal forces acting longitudinally upwardly thereof. In this respect, the handle assembly is a one-way clutch. The handle look assembly includes a shaft 34, the inner end of which supports the pinion 30 and the outer end of which is rotatably received in a bushing 35. Fixedly secured intermediate the rod end is a four-sided cam 36. The cam is receivable in a cylinder-like member 38 which extends inwardly of bushing 35. The interior diameter of member 38 is only slightly greater than the diagonal length of cam 36.

The cylinder 38 is formed with a plurality of slots 39. A plastic body 44 encompasses the cylinder and forms with the cam 36 and slots 39 a series of chord-like chambers 40, each of which houses a pin 42. The body 44 is provided with an outer flange 45 which is secured to standard 16 by screws or the like.

An understanding of the handle lock assembly can best be had by referring to FIGURES 4, and 6. As previously described, the member 44 is fixed to the standard, and the shaft 34, cam 36 and pinion rotate as a unit. The outer end of shaft 34 is rotatably secured in the handle unit consisting of cylinder 44, bushing 35, and handle 37. Therefore, as the cylinder 44 is rotated counterclockwise (clockwise as viewed in FIGS. 5 and 6) under the influence of the handle 37, the rack 28 is lowered toward the lens and lap.

Prior to the rotational movement in handle 37 acting on pinion 30, a certain amount of free-play occurs between the cylinder 44 and the cam 36. For purposes of description, the location of elements as viewed in FIG- URE 5 can be termed a neutral position. As the cylinder 38 is rotated, the pins 42 receive a lateral or circumferential force along arrow F wedging them into the narrow portion of their respective chordal chambers 40, as seen in FIGURE 6. When resistance is met and the pins bind between the sides ofcam 36 and the interior of member 44, the shaft 30 will then rotate with the handle whereby the head asembly is lowered.

Thereafter, forces attempting to lift rack 28 will transmit a rotational force in shaft 34 which acts generally along the force lines 43 of FIGURE 6. Such forces are dissipated in further compressing the pins rather than ro tating the cylinder. When it is desired to lift the rack, the handle 37 is moved in the opposite direction, creating circumferential forces 47 which readily dislodge the pins. The rack begins an upward movement when the pins bind at the opposite narrow portions of chambers 40.

As previously mentioned, the rack 28 supports the drive assembly 26. The lowermost end of the rack is formed with a pocket which receives the upper end of stub shaft 48. The shaft is fixedly secured to the pocket by set screws or the like. A joint 49 consisting of three brackets is formed between the rack and the assembly 26. The lower end of the shaft is formed with a bracket member 50. Downwardly depending from each end of the bracket are a set of conical bearings 52 and 54. Disposed immediately below the bracket is second bracket 56 having sockets 58 and 59 for respectively receiving the bearings 52 and 54. A pair of arms 60 and 62 extend outwardly and upwardly from the midportion of bracket 56 as best seen in FIGURE 3. Depending downwardly from the outer ends of arms 60 and 62 is a second set of conical bearings 64 and 66 which are receivable respectively in sockets 68 and 69 of a third bracket 70. The bracket 70 is provided with an opening 72 to removably receive the upper end of a lower shaft 74. The bracket 70 is tightened about the shaft 74 via a bolt 75. The brackets 50, 56 and 70 form a suspension joint 71 for purposes described hereinafter. The brackets are held in engagement with one another by an endless resilient band 73 having one end looped under one end of bracket 70 across the upper surface of bracket 50 and below the end of arm 70.

The lower end of shaft 74 forms the upper end of a pneumatic cylinder 76. Slidably received in cylinder 76 is a piston 78 having a piston rod 80 extending downwardly through the other end of the cylinder. Fixedly secured to the bottom of rod 80 is a yoke 82. The yoke carries a rocker 84 which is pivotally suspended therefrom by linkage arms 88 and 90. The rocker carries a transverse crossbar 92 having pins 94 which are adapted for driving engagement with the conventional recesses of the lens block B.

Intermediate the length of rod is a circular sheavelike member 95. As seen best in FIGURE 7, the rod is offset from the center of the sheave an amount D for causing the rod to travel a circular path as the sheave is rotated. A strap 98 engages the sheave 96 and also engages apparatus in housing 10 for transmitting the continuous orbital or circular movement to the head. The orbital movement, of course, must be limited in diameter so that the lens will always be within the periphery defined by the break-up movement.

The expansion chamber 99 of the cylinder 76 is pressurized via a source of pressurized air 100. A schematic of the pneumatic and timing valves is shown in FIGURE 8. The source of pressurized air is divided into two branches by conduits 102 and 104. Across conduit 102 is laced a pressure regulator 106 and across conduit 104 is placed a pressure regulator 108. The regulators are of an adjustable type and desirably the regulator 106 is set at approximately 10-20 p.s.i. and regulator 108 at from 70-90 p.s.i.

A timing apparatus 110 of a conventional re-set type is connected to operate the solonized air valves 112 and 114 which are respectively placed across conduits 102 and 104. For the first several minutes of operation, the timer is set to open the valve 112 to permit the lower regulated pressure in line 102 to be communicated to line 116 and chamber 99 and, thereafter, close valve 112 and open line 116 and chamber 99 to the higher pressure by opening valve 114. A pressure indicator dial 118 is placed across conduit 116 for informative reasons.

In operation, an attendant first places a lap of the desired cylindrical configuration on the supports 13 and 13a. Thereafter, a blocked lens blank B is centrally placed over the lap. While holding the lens in position with one hand, the attendant grasps handle 37 with the other to lower the head assembly 26 until pins 94 engage the appropriate recesses formed in the rear of the lens block. As has previously been described, insofar as movement longitudinal of member 28 is concerned, only that movement transmitted through handle 37 can now affect the raising or lowering of the upper portion of the head assembly.

Upon turning the timer to its start position, pressure is applied into chamber 99 via the low pressure regulator 106 and conduit 102. Once chamber 99 is pressurized, the force maintaining the lens into engagement with the lap is solely determined by the pressure. regulators and not handle 37. As has been previously mentioned, the initial low pressure is regulated by member 106 and is maintained on the lens for a period of approximately five minutes. Thereafter, the timer automatically communicates the higher pressure regulated by regulator 108 to chamber 99 until final polishing is accomplished. During the period that pressure is applied and the lap support members are receiving the break-up movement, the head 26 is orbited due to the rotation of sheave 95.

The importance of the joint 49 can now be readily understood. As the head is orbited, but not rotated since rod 80 is not fixed rotationally with sheave 95, the rack 28 stays stationary and the rest of the head assembly is pivotal at joint 45. The pivoting movement occurs in a plane 120 which intersects each of the pivot points at pins 64, 66, 52 and 54. In other words, a four point suspension in a common plane is available which is readily disconnected by removing the resilient band 73. The joint is of a type uniquely adapted to take the longitudinal thrusts which are transmitted by the pressure apparatus and the radial thrusts which are transmitted by the orbiting apparatus.

In a general manner, while there has been disclosed an effective and efiicient embodiment of the invention, it should be well understood that the invention is not limited to such an embodiment, as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

We claim:

1. A lens surfacing machine of the type having an abrading lap receiving irregular movements in a common plane and a lens blank supporting structure for maintaining the blank in engagement with the lap, the improvement in said structure comprising a framework forming a part of the machine, a supporting head assembly disposed above said lap and having an uppermost end slidably received in said framework, a cradle at the lower end of said assembly, means to lower said assembly until said cradle engages said blank, pneumatic means for maintaining a desired pressure on said cradle, a resilient universal joint intermediate the ends of said assembly between said cradle and that portion of said framework slidably receiving said shaft.

2. A lens surfacing machine of the type having an abrading lap having irregular movements in a common plane and a lens blank supporting structure for maintaining the blank in engagement with the lap, the improvement in said structure comprising, a framework forming a part of the machine, a supporting head assembly disposed above said lap, said assembly comprising a first member slidably disposed with respect to said framework for movement toward and away from said lap, a locking mechanism mounted on said framework for holding a portion of said first member at a selected position with respect to said lap, a pneumatic cylinder attached to one end of said first member, a drive member having one end forming an expansion chamber with said cylinder and a second end for engagement with said blocked lens, a pivotal joint intermediate the length of said first memher and between said portion and said pneumatic cylinder, at first source of relatively high air pressure, a second source of relatively low air pressure, a conduit network for communicating said first and second sources to said chamber, time controlled valve means across said network for communicating said high pressure source to said chamber a selected period of time after said low pressure source has been communicated thereto.

3. A lens surfacing machine of a type having an abrading lap having irregular movements in a common plane and a lens blank supporting structure for maintaining the blank in engagement with the lap, the improvement in said structure comprising, a framework forming a part of the machine, a supporting head assembly disposed above said lap, said assembly comprising a first member slidably disposed with respect to said framework for movement toward and away from said lap, a pneumatic cylinder attached to one end of said first member, a drive member having one end forming an expansion chamber with said cylinder and a second end for engagement with Cir said blocked lens, means driving said drive member about a circular path over said lap, a first source of relatively high air pressure, a second source of relatively low air pressure, a conduit network for communicating said first and second sources to said chamber, time controlled valve means across said network for communicating said high pressure source to said chamber a selected period of time after said low pressure source has been communicated thereto.

4. A lens surfacing machine of the type having an abrading lap having irregular movements in a common plane and a lens blank supporting structure for maintaining the blank in engagement with the lap, the improvement in said structure comprising, a framework forming a part of the machine, a supporting head assembly disposed above said lap, said assembly comprising a first member slidably disposed with respect to said framework for movement toward and away from said lap, a pneumatic cylinder attached to one end of said first member, a resilient joint between said first member and said cylinder, a drive member having one end forming an expansion chamber with said cylinder and a second end for engagement with said blocked lens, means driving said drive member about a circular path, and a source of pneumatic pressure communicated to said cylinder for urging said drive member toward said lap.

5. The machine of claim 1 wherein said assembly includes a vertically disposed cylindrical middle portion, a shaft means enclosing the upper end of said cylindrical portion and extending upwardly therefrom, a piston rod having its upper end slidably disposed in the lower end of said middle cylindrical portion and forming an expansion chamber with said shaft means and means communicating said expansion chamber with said pneumatic means.

6. The invention of claim 5 wherein said resilient universal joint is disposed intermediate the ends of said shaft means.

7. The invention of claim 5 wherein said resilient universal joint is intermediate the ends of said shaft means between said uppermost end and said cylindrical middle portion.

References Cited UNITED STATES PATENTS 766,482 8/1904 Wolfe 51---l24 1,230,530 6/1917 Stead 51133 2,159,620 5/1939 Long 51---160 2,624,981 1/1953 Kenyon 51-56 X 2,880,555 4/ 1959 Brueckner 51124 X 2,977,724 4/1961 Kennedy 51-124 3,172,240 3/1965 Giardini 51-165 X HAROLD D. WHITEHEAD, Primary Examiner.

Claims (1)

1. A LENS SURFACING MACHINE OF THE TYPE HAVING AN ABRADING LAP RECEIVING IRREGULAR MOVEMENTS IN A COMMON PLANE AND A LENS BLANK SUPPORTING STRUCTURE FOR MAINTAINING THE BLANK IN ENGAGEMENT WITH THE LAP, THE IMPROVEMENT IN SAID STRUCTURE COMPRISING A FRAMEWORK FORMING A PART OF THE MACHINE, A SUPPORTING HEAD ASSEMBLY DISPOSED ABOVE SAID LAP AND HAVING AN UPPERMOST END SLIDABLY RECEIVED IN SAID FRAMEWORK, A CRADLE AT THE LOWER END OF SAID ASSEMBLY, MEANS TO LOWER SAID ASSEMBLY UNTIL SAID CRADLE ENGAGES SAID BLANK, PNEUMATIC MEANS FOR MAINTAINING A DESIRED PRESSURE ON SAID CRADLE, A RESILIENT UNIVERSAL JOINT INTERMEDIATE THE ENDS OF SAID ASSEMBLY BETWEEN SAID CRADLE AND THAT PORTION OF SAID FRAMEWORK SLIDABLY RECEIVING SAID SHAFT.

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