Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
  • B24B13/02—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor by means of tools with abrading surfaces corresponding in shape with the lenses to be made
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B41/00—Component parts such as frames, beds, carriages, headstocks
  • B24B41/04—Headstocks; Working-spindles; Features relating thereto

Definitions

• TITLE METHOD AND APPARATUS FOR POLISHING OPHTHALMIC LENSES
• This invention pertains to the polishing of ophthalmic lenses, and more particularly, it pertains to a method and an apparatus for polishing ophthalmic lenses, using a lapping tool having a dynamically formable lapping membrane.
• a lens polishing operation is limited to the removing of minor scratches and machining marks in a lens while maintaining perfectly the prescribed curvatures. It will be appreciated that any uncontrolled pressure point in a lapping membrane of a lapping tool head, or a depletion of polishing slurry at any location over the membrane can cause the polishing operation to remove more or less material in one region of the lens, thereby changing the prescribed curvature of that lens and causing optical defects.
• the first group utilizes a lapping tool head having a resilient or flexible lapping membrane which is deformable upon contact with the surface of a lens to adapt to the curvature of the lens. Examples of apparatus belonging to this first group are described in the following US Patents:
• the second type of lens polishing apparatus of the prior art uses a plurality of plungers for applying pressure gradients over a lens polishing membrane. Although these apparatus are designed for polishing large telescope mirrors, this is the type of apparatus that is of interest herein. Examples of these apparatus are illustrated in the following US Patents: US 4,606,151 issued on Aug. 19, 1986 to Erich Heynacher; US 4,802,309 issued on Feb. 7, 1989 to Erich Heynacher;
• polishing apparatus having a plurality of actuators for applying different pressures at different areas of a polishing membrane.
• the different pressures are adjusted according to the amount of material to be removed at different locations on the lens surface, such that a polishing operation is effected more quickly.
• These apparatus have undeniable merits and are believed to be great advances in the polishing of optical surfaces.
• a new method for polishing an ophthalmic lens there is provided a new method for polishing an ophthalmic lens.
• a lapping tool head that is adapted to simultaneously conform to the shape of an ophthalmic lens and to move abrasive slurry between the membrane thereof and the ophthalmic lens being polished.
• an improved method for polishing an ophthalmic lens surface using an apparatus having a lapping tool head, a flexible membrane covering a lapping portion of that tool head, and pump and nozzle means for pumping abrasive slurry over the lapping tool head comprises the conventional step of imparting an oscillatory movement to the lapping tool head and contacting the lens surface with the lapping portion of the lapping tool head while an abrasive slurry is pumped over the lapping tool head and on the lens.
• the improvement comprises the additional step of periodically undulating the membrane for imparting a wave in that membrane such that the abrasive slurry can flow between the membrane and the lens surface.
• a major advantage of this new method is that the lapping slurry is efficiently moved over the entire surface of the lens for improving the quality of the lenses polished by this process.
• the new method also includes the step of shaping the membrane along a pair of right angle axes and defining membrane profiles along these axes that are respectively similar to and aligned with a base and cross curvatures of the lens being polished. This shaping of the membrane ensures that a lapping operation
• a lapping tool head for polishing ophthalmic lenses.
• the lapping tool head comprises a base plate having mounting means for securement thereof to a lens polishing apparatus, and a plurality of pneumatic fittings mounted in that base plate.
• a manifold plate is affixed to the base plate and has pneumatic circuits therein with each pneumatic circuit communicating with one of the pneumatic fittings.
• a plurality of pneumatic cylinders is affixed to the manifold plate, and defines a circular array of parallelly-aligned cylinders, with each cylinder being connected in a sealed communication with a respective one of the pneumatic circuits.
• a rigid shield encircles all the cylinders, and individually encloses a collar end of each cylinder, opposite the manifold plate.
• an elongated sleeve immovably affixed to the shield in a central region of the circular array, and being aligned with the cylinders, and a flexible membrane covering the cylinders and the shield.
• the membrane has a stem extending therefrom and into the sleeve and being secured into the sleeve.
• Each cylinder has an extendible end which is movable against the flexible membrane for shaping the membrane.
• the cylinders are individually controllable for shaping the membrane according to the curvatures of an ophthalmic lens.
• a central portion of the membrane is usable as a reference
• the array of cylinders in the lapping tool head comprises an inner and outer concentric circles around the sleeve.
• the membrane is undulated in circular waves for advantageously moving lapping slurry over the surface of the lens.
• the array of cylinders is divisible in four diametrically opposite segments of the tool head, and the cylinders in each pair of opposite segments are operable in a group for generating radial waves in the membrane for the purpose of moving lapping slurry over the surface of the lens.
• the array of cylinders comprises two concentric circles.
• Each cylinder has an extendible end, and the extendible ends on the cylinders in the outer circle have D-shaped pads mounted thereon, with a short segment of the pad extending along a circumference of the circular array, and each pad being pivoted on a respective extendible end, along an axis which is also aligned with the circumference of the circular array.
• the extendible ends in the cylinders in the inner circle have suction- cup-shaped caps mounted thereon.
• the suction caps are optionally connectional to a source of a vacuum as well as the cylinders in the inner circle. Therefore when the cylinders in the outer circle are connected to a source of pressure and the cylinders in the inner circle and the suction caps
• this array of cylinders is usable for shaping the membrane according to extreme lens curvatures.
• the array of cylinders is a compact arrangement that is substantially similar to an area defined by a common ophthalmic lens blank.
• the array of cylinders is mountable in a tool head that has a common size and that is adaptable to conventional lens lapping and polishing apparatus, for retrofitting an existing lens polishing apparatus for example, thereby making such lapping tool head economically available to the optical industry.
• FIG. 1 is a simplified illustration of a lens polishing apparatus according to the preferred embodiment of the present invention. For more clarity, the apparatus is shown without the usual drive motor, control equipment, cabinetry and other equipment common to this type of machines;
• FIG. 2 is a side view of an ophthalmic lens mounted on a support block
• FIG. 3 is a closeup view of the lapping tool head comprised in the lens polishing apparatus
• FIG.4 is a partial perspective view of the polishing station inside the lens polishing apparatus
• FIG. 5 is a partial side elevation view of the lens polishing station
• FIG. 6 is an enlarged perspective view of the lapping tool head of the lens polishing station, with the covering membrane thereof shown in a cut-away view;
• FIG. 7 shows the lapping tool head without the covering membrane
• FIG. 8 shows a plan view of the lapping tool head without the covering membrane
• FIG. 9 is a cross-section view through the lapping tool head as seen along line 9-9 in FIG. 8;
• FIG. 10 is a plan view of the manifold plate incorporated in the base of the lapping tool head
• FIG. 11 is a pneumatic circuit diagram used in association of the lapping tool head
• FIG. 12 is a schematic illustration representing an ideal path of the lapping tool head on an ophthalmic lens
• FIG. 13 is a schematic plan view of the lapping tool head illustrating the various pressure zones therein when these pressure zones are operable in diametrically opposite sectors;
• FIG. 14 is another schematic plan view of the lapping tool head illustrating the various pressure zones therein when the pressure zones are operable in concentric circles.
• FIGS. 1, 2 and 3 illustrating respectively, a simplified perspective view of the apparatus according to a preferred embodiment of the present invention, for carrying out a new method for polishing ophthalmic lenses, atypical ophthalmic lens mounted on a support block, and a lapping tool head incorporated in the apparatus.
• the polishing of ophthalmic lenses referred to herein pertains to an optional step in the manufacturing of ophthalmic lenses on an ultra-precision lens generating apparatus wherein the final curvature of a lens' surfaces is determined by a machining process and shall not be altered during the polishing operation.
• the polishing of ophthalmic lenses is a light lapping operation which is optionally carried out to remove invisible or hardly visible machining defects from the lens' surfaces, in order to produce lenses of a finest
• the polishing of the lenses is carried out prior to applying an optional final clear resinous coating to the lenses.
• the apparatus comprises in combination: a wash station 20; a polishing station 22 and a robotic manipulator 24 for transporting an ophthalmic lens 26 with a lens block 28 affixed thereto from a placement station (not shown) to the wash station 20; from the wash station 20 to the polishing station 22; and from the polishing station 22 back to the wash station and then to a placement station (not shown) where an operator can remove the lens 26 from the apparatus.
• a placement station may be incorporated into the wash station, and the lens 26 and block 28 may be initially placed in the wash station 20 by an operator of the apparatus.
• the robotic picker 24 comprises a gripper assembly 40, for engaging and holding the lens block 28, and a pair of a first and second linear actuators and slide assemblies 42,44 for moving the gripper assembly 40 in transversal and longitudinal directions respectively as indicated by arrow 42' and 44'.
• the robotic picker 24 is preferably also movable in up and down directions to grab and release a lens block 28.
• the lens 26 is preferably introduced in the wash station or in the lens placement station (not shown) by manually orienting a reference slot 50 with a corresponding indentation (not shown) in the chuck of one of these stations.
• the wash station 20 comprises a first vacuum chuck 60 (similar to 80 in FIG.3), for retaining the lens block 28.
• the first vacuum chuck 60 is mounted on the arbor of a rotary actuator 62 such that the lens 26 is rotatable during the wash cycle.
• the first vacuum chuck 60 has a splash guard plate 70 movably attached thereto, and a spray nozzle 72 is mounted inside the wash basin 64.
• the wash basin 64 rises up against the splash guard plate 70 and encloses the lens 26, the lens block 28 and the spray nozzle 72 completely. Water or a mixture of water and detergent is then sprayed against the lens while the lens 26 rotates several turns.
• the lens 26 is transferred to the polishing station 22 by the robotic picker 24.
• the polishing station comprises a second vacuum chuck 80 for holding the lens 26 during the polishing cycle.
• the second vacuum chuck 80 for holding the lens 26 during the polishing cycle.
• a lapping tool head 82 is mounted above a lapping tool head 82 such that the surface of the lens 26 to be polished is oriented downward facing the top portion of the lapping tool head 82.
• the second vacuum chuck 80 is mounted on a second structure which is only partly drawn for maintaining the clarity of the drawing.
• the second structure comprises a fourth, fifth and sixth linear actuators and slide assemblies 84, 86 and 88 respectively. These linear actuator and slide assemblies are operable for moving the second vacuum chuck 80 in three
• Such movements of the second vacuum chuck 80 are advantageous for initially positioning the geometrical center of the lens to coincide with the vertical neutral axis of the lapping tool head 82, or for initially positioning the lens a nominal offset distance relative to the neutral axis of the lapping tool head to accommodate a prism angle in that lens for examples. It is also recommended to continually moving the lens 26 back and forth and side to side in directions indicated by arrows 84' and 86' relative to the neutral axis of the lapping tool head during the polishing cycle to prevent localized over or under-polishing of the lens.
• the second vacuum chuck 80 and the lapping tool head 82 are preferably mounted inside a sealable enclosure 100.
• the enclosure 100 preferably has a glass window 102, and the wash basin 64 is preferably made of transparent material such that both operations may be monitored by an operator standing near the apparatus.
• a continuous flow of lapping slurry is pumped over the lapping tool head 82 and the lens 26 by one or more slurry nozzles as indicated by numeral 104 in FIG. 3.
• the lapping tool head 82 of the apparatus is operated in a circular oscillatory movement by a mechanism of the type described, for example, in US Patent No. 5,175,961 issued on Jan. 5, 1993 to John R. Bolton. Rotary power is applied to the mechanism at pulley 106.
• the vacuum chuck 80 and the lapping tool head 82 are illustrated therein in a larger scale.
• the second vacuum chuck 80 is only partly illustrated therein.
• this chuck 80 as well as the first chuck 60, are operated by a vacuum and are connected to a source of a vacuum and appropriate control valves, by a conduit such as the one illustrated and identified by label 110.
• the vacuum chuck 80 is mounted on a gimbal 112, which in turn is mounted on a vertical brace 114 affixed to the sixth linear actuator 88. This preferred mounting is better illustrated in FIGS. 4 and 5.
• the gimbal 112 comprises a first C-shaped member 116 which is pivoted at its center along a first axis of articulation 118 passing through a first bearing (not shown) in the vertical brace 114.
• a second C-shaped member 120 has its ends respectively connected to the ends of the first C- shaped member 116, along a second axis of articulation 122 perpendicular to the first axis 118.
• the second C-shaped member 120 has a flat surface 124 on an upper side thereof, as illustrated in FIG. 5. This flat surface is advantageously used for selectively contacting a stay member 126 there- against, for orienting and stabilizing the gimbal 112 during the insertion of a support block 28 in the chuck 80 or when removing a support block from the chuck.
• the stay member 126 is a flat- ended circular member mounted on the extension rod of a linear actuator 128.
• the lapping tool head 82 is preferably covered by a fabric hat 130 enclosing the active part thereof completely.
• the fabric hat 130 is held about the tool head by an elastic band 132 below the enlarged portion of the tool head.
• the fabric material of the fabric hat 130 is selected such that it has good endurance and good characteristics related to the absorption and retention of lapping slurry.
• a preferred type of fabric material for use in manufacturing the fabric hat 130 is sold by DuPont TM under the trade name Wearforce TM "F".
• DuPont TM E.I. du Pont de Nemours and Company, has offices across the world with its corporate headquarters at: 1007 Market Street, Wilmington, DE, 19898, U.S.A.
• the central region of the lens 26 may be deprived from an abundant circulation of slurry, as compared to the peripheral regions of the lens for example.
• the slurry has a liquid phase, normally water, and a solid phase comprising microscopic abrasive particles, normally aluminum oxide particles, typically of no more than five (5) microns in size.
• the purpose of the liquid phase is to carry the abrasive particles over the entire area to be polished, and to wash away the abraded particles of plastic or glass from the lens.
• the slurry is not distributed uniformly over the entire surface of the lens. This inconvenience can cause an uneven wear of the fabric hat 130 covering the lapping tool head 82.
• the uneven distribution of slurry across the entire surface of the lens can also cause an uneven polishing of the lens.
• the lapping tool head 82 of the preferred embodiment has a curved membrane 134, as illustrated in FIGS. 3 and 6, and a number of pneumatic cylinders 136 mounted under the membrane for shaping the membrane according to the curvature of the lens 26, and for maintaining an even pressure distribution between the absorbent fabric hat 130 , the membrane 134, and the entire surface of the lens 26.
• the membrane 134 is preferably made of a flexible rubber material that is water-impermeable, for preventing slurry from deteriorating the mechanisms and equipment associated with the pneumatic cylinders 136.
• the pneumatic cylinders 136 of the lapping tool head 82 perform the additional functions of periodically undulating the membrane 134 for moving lapping slurry between the membrane and the lens 26.
• the lapping tool head 82 comprises eighteen (18) pneumatic cylinders 136 disposed in a circular or hexagonal array around a central sleeve 138 .
• the circular or hexagonal array preferably has a diameter slightly smaller than a diameter of a standard lens blank.
• the array of pneumatic cylinders 136 comprises two concentric circles; the outside circle has twelve (12) outer plungers 140 and the inner circle has six (6) inner plungers 142.
• each pneumatic cylinder 136 is a single-action, spring-returned, collar-mount type, .and the stroke length of each one is selected such that it operates in a mid-stroke region thereof
• the curvature of the membrane 134 of the lapping tool head of the apparatus is preferably adjustable from a slightly concave shape, about minus six (-6) diopters, to a planar configuration and to a convex curvature of about sixteen (16) diopters.
• each outer plunger 140 has a D-shaped pad 144, in which the short segment defines an arc along the circumference of the circular array.
• Each D-shaped pad 144 is pivoted to the rod end on a pin 146 (in FIG. 9) through the rod end and extending along the short segment mentioned above. This configuration of the pads 144 is advantageous for working the membrane 134 over its entire active area, and especially along the circumference thereof.
• the rod ends of the inner plungers 142 preferably have vacuum- type cup-shaped caps 148.
• the shape of these caps 148 is advantageous for applying an even distribution of pressure under the membrane when the pneumatic cylinders 136 of these plungers are actuated outwardly.
• the shape of these cup-shaped caps 148 is also advantageous for optionally applying a vacuum thereto and a corresponding pulling force on the membrane for shaping the membrane into a flat configuration for example, or for undulating the membrane for moving polishing slurry thereunder, as will be explained later.
• the pneumatic cylinders 136 operating the inner plungers 142 preferably have hollow rods communicating with a vacuum supply port, and are of the single-action spring-extended type. It will also be appreciated that the inner plungers 142 with the caps 148 mounted thereon are also connectional to a source of a vacuum while their
• respective cylinders 136 are connectional to a source of air pressure.
• each cylinder has a vacuum and pressure ports; the vacuum port being connected to a hollow plunger rod and the pressure port being connected to the piston outside that rod.
• This configuration has not been illustrated for being common to the persons skilled in pneumatic systems, and would be evident to these persons in the light of the present specification.
• the central sleeve 138 is fixed relative the inner and outer plungers 140,142. It has a longitudinal axis extending in a parallel alignment with the axes of the pneumatic cylinders 136.
• the sleeve 138 defines a neutral axis of the tool head 82.
• the central sleeve 138 has an inside dimension for receiving and holding a stem 150 extending from the central region inside the membrane 134.
• the stem 150 is firmly retainable inside the sleeve 138 such that the stem 150 provides a reference point for shaping the membrane according to the surface to be polished.
• the stem 150 is preferably made of resilient rubber, as for the membrane 134 itself, and is bonded to or molded as an integral part of the membrane 134.
• the portion of the membrane near the stem 150 is positional against the lens, thereby providing a fixed base which is preferably maintained in contact with the surface of the lens, and from which the membrane may be profiled to match the curvatures of the lens being polished.
• the portion of the membrane near the stem 150 also provides a reference point for moving the lapping tool head 82 against a lens to be polished, when a pressure measuring device is used to control the movement of the sixth linear actuator 88.
• the sixth linear actuator 88 preferably comprises a pneumatic linear actuator (not shown) that is connected to an adjustable high precision pressure regulator (not shown). This pneumatic
• each cylinder 136 is seated in a manifold plate 154 and is sealed in a respective cavity in the manifold plate.
• the manifold plate 154 and the pneumatic cylinders 136 are surrounded by a rigid shield 155.
• the shield also encloses a collar end of each pneumatic cylinder, opposite the manifold plate 154, for retaining these cylinders 136 in a spaced-apart and parallel alignment.
• the sleeve 138 is also affixed to the shield 155 and extends in a parallel relationship with the cylinders 136.
• the shield 155 has one or more slots 158 on the outside surface thereof for mating with one or more similar ribs (not shown) inside the membrane 134, and for indexing and retaining the membrane thereon.
• the manifold plate 154 has six (6) circuit grooves 156 therein connecting one or more cylinders 136 to one of six (6) holes 158 communicating with one of six (6) pressure supply fittings 160 extending from a base plate 162 of the tool head 82.
• the base plate 162 is mountable to the arbor of the oscillatory mechanism by means of bolts through countersunk holes as illustrated.
• the six (6) circuit grooves 156 connect two or more cylinders 136 to form with the central stem 150, seven (7) pressure zones of the lapping tool head 82. Each zone is labeled with a letter symbol from 'A' to 'G' as illustrated in FIGS. 8, 13 and 14.
• Each of the supply fittings 160 is connected to a solenoid operated pneumatic valve 164 which in turn is connected to an air pressure supply manifold 166. There is provided on the supply port to the air pressure
• each cylinder 136 supply manifold 166, a precision proportional pressure regulator 168.
• the pressurizing of each cylinder 136 is effected by operating one solenoid valve 164 at the time and changing the pressure setting of the pressure regulator 168 at each time.
• the pressure regulator 168 is a computer- controlled, fast-response type where the closing and pressurizing of all six lines are effected in a very short time and in fact in few seconds.
• the pressure in each cylinder 136 is preferably adjusted repeatedly during the entire period of operation of the lapping tool head.
• a similar circuit (not shown) is used for controlling the vacuum setting in these plungers, in the caps 148 of these plungers or in both the plungers 142 and the caps 148.
• a seventh circuit groove 170 and a seventh hole 172 are shown in the manifold plate 154.
• This circuit groove is also connected to a pressure supply fitting 160 and to the air pressure supply manifold 166 and regulator 168.
• the circuit groove 170 is connected to an access hole 174 through a central region of the tool head 82 as illustrated in FIG. 9.
• the membrane 134 is preferably sealed around the shield 155, in groove 176 for example as shown in FIGS. 6 and 9.
• air pressure is admitted through conduit 174, this pressure is transmitted inside the tool head and under the membrane 134 to inflate the membrane.
• a slight positive pressure inside the membrane is at time advantageous for reducing localized pressure concentration areas at each plunger 140 or 142.
• a vacuum may also be applied to the circuit groove 170 for obtaining extreme curvatures in the membrane 134 for example.
• zone 'A' on this drawing is representative of the travel of the central area of the tool
• a satisfactory diametrical setting on the apparatus of the preferred embodiment is between about 10 to about 20 mm and a preferred velocity is between about 300 and 600 cycles per minute for polishing a lens having a diameter of about 75 mm.
• FIG. 13 This figure illustrates a plan view of the lapping tool head 82 and the seven regions defined by the stem 150 and the plungers 140,142. The configuration of these regions is such that it is possible to group one or more zones to define four sectors as illustrated in this figure.
• Sectors 180 and 182 are opposite and symmetrical.
• Sectors 184 and 186 are also opposite and symmetrical, and disposed at right angle with sectors 180 and 182.
• Sectors 180 and 182 are disposed along the axis 188 of the cross curve of a lens to be polished on that head for example, herein referred to as the cross curve axis.
• the sectors 184 and 186 are disposed along the base curve axis 190. It will be appreciated that all zones on one side of the cross curve axis 188 are positioned in a symmetrical manner relative to the zones of the other side of that axis.
• the position of the zones on one side of the base curve axis 190 are symmetrical to the zones of the other side of that axis. Therefore, each zone on the lapping tool head is positioned in a four-way symmetrical arrangement relative to the commonality of that zone with both orthogonal axes 188 and 190 of
• the pressure settings of the pressure zones defined by sectors 180 and 182 are adjustable according to the shape of the cross curve of the prescribed lens to be polished.
• the pressure settings in the regions defined by sectors 184, and 186 are adjustable according to the shape of the base curve of the prescribed lens.
• the ability to create pressure gradients along two pairs of opposite sectors has proven to be advantageous for shaping right-angled profiles in the membrane 134 of the tool head 82 according to both basic curvatures of a lens 26, and thereby obtaining uniform polishing of the lens surface.
• FIG. 14 Another important characteristic of the lapping tool head 82 of the preferred embodiment is illustrated in FIG. 14 and is also directly related to the symmetrical arrangement of the pressure zones on the tool head.
• the eighteen (18) pneumatic cylinders 136 of the tool head 82 are arranged in seven zones as it was previously mentioned for forming four (4) symmetrical sectors 180,182,184,186.
• the seven zones are also configured to form three (3) concentric circles or three concentric hexagons.
• the first circle 192 comprises a single zone 'A' having a fixed stem 150.
• the second circle 194 comprises two zones; 'B' and 'E' having respectively four and two pneumatic cylinders 136.
• the third circle 196 comprises four zones; 'C, 'D', 'F' and 'G' having respectively two cylinders, four cylinders, four cylinders and two cylinders.
• Each cylinder 136 in each of zones 'B' to 'G' is diametrically and symmetrically opposite from another cylinder in a same zone.
• the pressure in all the pneumatic cylinders along each circle 194 and 196, or the vacuum setting in plungers 142 in circle 194, may be periodically reduced from, or increased above their prescribed settings, to cause the membrane 134 to flex at controlled locations and to cause the membrane to undulate against the surface of the lens 26.
• the circular arrays 194 and 196 are workable separately and in sequence to pump in a nominal quantity of abrasive slurry toward the center of the lens 26, or to expel slurry from the central region of the lens toward the periphery of the lens. This controlled undulation of the membrane 134 and the pumping action created thereby is advantageous for maintaining a constant supply of abrasive slurry across the entire surface of the lens.
• each circle is diametrically symmetrical in relation to the configuration of the lapping tool head, and because each zone may be actuated for a specific time duration, the polishing effect of the tool head during the undulation of the membrane is controllable to ensure a uniform polishing action across the entire surface of the lens.
• the pumping action by way of undulating the membrane in pulsating circular waves may be preferred by some users when the curvature of the membrane is near a maximum value.
• the pressure gradient in each pair of sectors 180-182 and 184-186 may be alternatively varied for generating pulsating radial waves in the membrane 134 and for undulating the membrane 134 in a sweeping-like manner to take in and spread the abrasive slurry over the entire surface of the lens.
• the programmed curvature of the membrane 134 is always maintained before and after the formation of each wave and at the nodes of each wave.
• the pulsating effect described herein is known to greatly improve a lens polishing operation, those who are familiar with lens polishing processes will appreciate that the pulsating effect described herein does not necessarily obviate completely the need to periodically raise the lens off the lapping tool head to renew the layer of lapping slurry there-between.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
• Eyeglasses (AREA)

Priority Applications (6)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25680009

Family Applications (1)

Country Status (11)

Cited By (2)

Families Citing this family (7)

Citations (2)

• 1999
  • 1999-01-27 CA CA002260484A patent/CA2260484C/en not_active Expired - Fee Related
  • 1999-01-28 AU AU21470/99A patent/AU2147099A/en not_active Abandoned
  • 1999-01-28 ES ES99901554T patent/ES2171323T3/es not_active Expired - Lifetime
  • 1999-01-28 JP JP53874399A patent/JP2001518022A/ja active Pending
  • 1999-01-28 EP EP99901554A patent/EP0971810B1/en not_active Expired - Lifetime
  • 1999-01-28 CN CN99800425.1A patent/CN1262639A/zh active Pending
  • 1999-01-28 KR KR1019997008873A patent/KR20010005800A/ko not_active Application Discontinuation
  • 1999-01-28 WO PCT/CA1999/000066 patent/WO1999038650A1/en not_active Application Discontinuation
  • 1999-01-28 PT PT99901554T patent/PT971810E/pt unknown
  • 1999-01-28 AT AT99901554T patent/ATE210000T1/de not_active IP Right Cessation
  • 1999-01-28 DE DE69900529T patent/DE69900529T2/de not_active Expired - Fee Related

Patent Citations (2)

Also Published As

Similar Documents

Legal Events