Abstract:
The invention relates to a method and an apparatus for producing optical glasses. The glasses are polished and marked, following a shaping process. The polishing and marking steps are carried out in a common processing cell which comprises a polishing station, a washing station, and a marking station.

Description:
CROSS REFERENCE TO OTHER APPLICATIONS  
       [0001]     The present application is a divisional of U.S. application Ser. No. 11/113,451, filed Apr. 22, 2005, which is a continuation of pending International patent application PCT/EP2003/11827, filed Oct. 24, 2003 which designates the United States and was published in German, and which claims priority of German patent application 102 50 856.9, filed Oct. 25, 2002. The disclosure of the above application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention is related to a method for producing optical glasses, in which the glasses are polished and marked following a shaping processing.  
         [0003]     The invention, further, is related to an apparatus for producing optical glasses, in which the glasses are polished and marked following a shaping process.  
         [0004]     A method and an apparatus of the type specified before are known from WO 01/66308 A1.  
         [0005]     The invention will hereinafter be described with regard to an application for spectacle lenses. However, it goes without saying that the invention may also be applied for other optical glasses.  
         [0006]     It is well known that so-called single-vision spectacle lenses are defined by two spherical surfaces or by one spherical and one toroidal surface. For optimising the central thickness and the peripheral thickness of single-vision spectacle lenses, a rotational symmetric aspherical function may be superimposed to the spherical or to the toroidal surface on one of the two sides of the lens.  
         [0007]     In contrast, so-called progressive power lenses or multifocal lenses have at least one optical free-form surface computed by optimisation software. The free-form surface is not rotationally symmetrical. Conventionally, it is located on the front surface of the spectacle lens. The so-called prescription surface, in contrast, is located on the toroidal rear surface of the spectacle lens and is adjusted to the optical characteristics of the spectacle user.  
         [0008]     Plastic material progressive power lenses are produced by molding. With this type of production, the optical free-form surface is generated already during the forming process. Spectacle lenses made from silicate, in contrast, are produced by an iterative sequence of processing steps of grinding and of polishing.  
         [0009]     The toroidal prescription processing is executed by grinding and polishing machines as are well known in the prior art.  
         [0010]     The prior art, further, comprises spectacle lenses, the optical characteristics of which are individually computed and optimised for any spectacle lens. Such prior art spectacle lenses, therefore, have at least one individually computed optical surface in a spline representation. The production of such individual optical surfaces is conventionally executed for non-rotationally symmetrical plastic material spectacle lenses by means of diamond lathing techniques. Such lathes are known from WO 97/13603 as well as from EP 0 758 571 B1. These prior art diamond lathes operate with an automatic feeding of the spectacle lenses in connection with a conveyor belt. The spectacle lenses are affixed to blocks and are transported in ordering boxes.  
         [0011]     When plastic material progressive power lenses are processed on their surface by means of a diamond lathing technology, they show a regular surface groove structure after the completion of the lathing process. This structure is of the order of 80 to 200 nm rms surface roughness. For obtaining the necessary final roughness of less than 10 nm rms, these lathed optical surfaces must still be polished. Finally, a so-called signature has to be applied. The signature or labelling is understood to be a marking for product identification on the one hand. On the other hand the application of two markings on each spectacle lens may define the optical axis, thereby assisting the optometrist to fit a lens into the spectacle frame in their correct position.  
         [0012]     As chips are generated during the polishing process, the polished surfaces must be cleaned from the chips and from the polishing agent and must be dried thereafter, prior to the subsequent marking step.  
         [0013]     A polishing machine, as may be used in the above-described context, is described in WO 01/56740 A1.  
         [0014]     In practice, for polishing lathed or ground free-form surfaces, polishing tools are used, in which a polishing surface is configured as a disposable polishing coating. The polishing surface is supported by an elastic foam structure such that the polishing surface may adapt itself to the shape of the spectacle lens. The polishing surface is shaped either convex or concave, depending on whether concave or convex spectacle lens surfaces shall be polished.  
         [0015]     After each polishing process the worn disposable polishing coating is detached from the polishing tool and is replaced by a fresh polishing coating. Following the detachment of the worn polishing coating the polishing tool is cleaned and dried.  
         [0016]     During the subsequent marking of the spectacle lenses the above-mentioned marking is conventionally applied into the spectacle lens surface pointwise, i.e. as a dot pattern, by means of a laser beam.  
         [0017]     All of the afore-described prior art apparatuses for polishing, washing and marking have in common that the spectacle lenses are fed individually, mostly manually.  
         [0018]     WO 02/00392 A1 describes an apparatus for loading and for unloading optical work pieces. This prior art apparatus is preferably used in connection with a grinding machine for optical single lenses. In this prior art apparatus, the spectacle lenses are handled by means of a suction head being applied to the optical surface of the spectacle lenses. Although it is likewise suggested to use a pneumatically operated three finger gripper, the latter shall, however, only be used for centering the spectacle lenses.  
         [0019]     U.S. Pat. No. 6,247,999 B1 discloses a method of automatically exchanging polishing tools. In this prior art method a plurality of polishing tools is placed ready in a row on a magazine bank. A robot picks up one of the polishing tools and attaches same to a gimballed suspension for the polishing tool at the drive element of the polishing machine. After completion of the polishing process the robot, together with the polishing tool moves into a device in which two metal sheets are arranged inclined with respect to the horizontal plane and enclose between them a gap. The robot enters the polishing tool into the gap and strips same off there. The worn polishing tool now falls downwardly into the inclined chute configured by the device and finally arrives at a container.  
         [0020]     EP 0 567 894 A1 discloses an apparatus for guiding a work piece or a tool during the processing of toroidal or of spherical surfaces of optical lenses on grinding or polishing machines.  
         [0021]     In this prior art apparatus a roller bellows is located at the lower free end of a spindle, the bellows supporting a polishing disk. An air pressure may be generated within a volume enclosed by the roller bellows, such that the polishing disk may be displaced axially. Moreover, the polishing disk is supported by an axially acting piston via a spherical joint. The roller bellows is adapted to transmit a torque for the polishing disk when rotated during operation.  
         [0022]     This prior art apparatus has the disadvantage that the roller bellows is a relatively stiff element such that the polishing disk may effect its proper movements only to a very limited extent.  
         [0023]     EP 0 974 423 A1 discloses another similar polishing disk, wherein the polishing tool may be attached to an actuator element via a bayonet joint.  
         [0024]     This prior art apparatus has the disadvantage that for attaching the polishing tool, the latter must be oriented in an angularly correct orientation relative to the actuator element.  
         [0025]     Another similar apparatus is disclosed in EP 0 974 422 A1.  
       BRIEF SUMMARY OF INVENTION  
       [0026]     It is, therefore, an object underlying the present invention to further improve a method and an apparatus of the type specified at the outset such that the afore-mentioned problems are avoided.  
         [0027]     In particular, it shall become possible to reduce the complexity of production as is necessary according to the prior art.  
         [0028]     In a method, specified at the outset, this object is achieved in that the steps of polishing and of marking are executed within a common processing cell.  
         [0029]     In an apparatus of the type specified at the outset, the object is achieved by an apparatus in which a polishing station, a washing station, and a marking station are arranged within one common processing cell.  
         [0030]     The object underlying the invention is thus entirely solved.  
         [0031]     The invention namely makes it possible for the first time to concentrate the entire production process for the prescription surface following the shaping process, which conventionally is executed by lathing or grinding, within one fully automated cell, such as to avoid the cumbersome manual work during loading and unloading of the spectacle glasses within the individual stations.  
         [0032]     Obviously, substantial production costs may thus be saved.  
         [0033]     In preferred embodiments of the invention the glasses are handled by the same robot during polishing and marking.  
         [0034]     This measure has the advantage that for all actions within the processing cell only one handling element is required, such that production costs are also reduced insofar.  
         [0035]     In a preferred embodiment of the inventive method it is particularly preferred when the robot 
        a) takes the glasses from a conveyor belt,     b) feeds the glasses to a polishing station and deposits them there,     c) takes a polishing tool from a tool magazine,     d) processes the glasses by means of the polishing tool,     e) deposits the polishing tool,     f) takes the polished glasses from the polishing station, feeds them to a washing station and deposits them there,     g) picks up a washing tool,     h) washes the glasses in the washing station,     i) deposits the washing tool,     j) takes the washed glasses from the washing station and feeds them to a marking station, and     k) takes the marked glasses from the marking station and deposits them on the conveyor belt.        
 
         [0047]     These measures have the advantage that by means of the one robot all handling actions, i.e. conveying actions between the various stations one the one hand as well as partly the processing steps, are assumed.  
         [0048]     In this context it is further preferred when the robot, between the execution of steps k) and l), executes one or more of steps a) through i) on at least one other glass.  
         [0049]     This measure has the advantage that the robot may operate on a time-multiplex basis, so that it may execute a handling on one glass while at the same time another glass is under processing otherwise, in particular within the marking station.  
         [0050]     In another preferred embodiment of the invention the glasses are conveyed on the conveyor belt within transportation boxes.  
         [0051]     This measure has the advantage that the glasses may be held at predetermined unloading and loading positions, wherein due to their arrangement in transportation boxes the handling may be executed under a defined orientation of the glasses.  
         [0052]     Finally, it is particularly preferred when the robot holds the glasses by means of a gripper which grips the glasses at their periphery.  
         [0053]     This measure has the advantage that the sensitive optical surface of the glasses remains untouched, in contrast to the prior art, so that any negative impact to these sensitive optical surfaces is made impossible.  
         [0054]     The afore-mentioned variant of the inventive method may be still more refined in that the glasses are gripped with a predetermined force.  
         [0055]     It is further preferred when the glasses are conveyed in pairs.  
         [0056]     This measure has the advantage that those glasses belonging to a particular ordering person (patient) may be handled and conveyed together or directly one after another so that it may be excluded that they become mixed up.  
         [0057]     It is further preferred when the glasses are arranged on a block for handling, i.e. for conveying and for processing.  
         [0058]     This measure has the advantage that in particular during polishing the glass itself must not be gripped.  
         [0059]     In a particularly preferred embodiment of the inventive method a polishing tool during polishing rests with a first surface on a second surface of the glass, wherein the first surface is smaller than the second surface, the surfaces, further, being rotated in the same direction and with essentially the same rotational speed, and wherein the first surface is guided over the second surface, in a radial direction. Insofar it is particularly preferred when an oscillating movement is superimposed on the radial movement in a direction perpendicular thereto.  
         [0060]     In contrast to the prior art, where the polishing tool is guided over the surface of the glass to be ground along parallel, distant paths, this feature has the advantage that no optically distinguishable patterns are generated. Instead, a surface is generated in which the locus of the polishing surface is no more distinguishable for the human eye.  
         [0061]     This holds true in particular, when the radial movement is guided along a diameter of the second surface.  
         [0062]     In this context it is, further, preferred when the radial movement and the oscillating movement are adjusted with respect to each other such that the locus of the center of the first surface assumes the shape of a mirror-symmetric undulated line during the radial reciprocal movement.  
         [0063]     In embodiments of the inventive apparatus one single robot is provided for handling the glasses between a conveyor, the polishing station, the washing station and the marking station, wherein the robot is preferably adapted for executing the polishing process, and, further, the robot is adapted for operating a polishing tool and the washing tool.  
         [0064]     These measures have the advantage that all of the movement and processing actions are executed by one and the same robot. Insofar, it has turned out as particularly advantageous when the glasses during the respective processing (polishing and washing) are held by a stationary, however movable holding unit, whereas the robot holds and moves the respective required tool (polishing tool or washing tool).  
         [0065]     In this context it is, further, preferred when the robot has a hand, wherein the hand by means of an axial actuator is adapted to be alternately brought into two operational positions, the hand having a gripper for gripping a glass and an interface for attaching a tool, the gripper in a first operational position being adapted for gripping and for depositing a glass, and in a second operational position for gripping and for depositing a tool.  
         [0066]     This measure has the advantage that the door-to-door time within the processing cell may be further reduced because it is no more required to provide a special change step for the gripper or the tool holder at the hand of the robot.  
         [0067]     In a preferred improvement of this embodiment the axial actuator is a rotary actuator.  
         [0068]     This measure has the advantage that a particularly simple sequence of movements may be obtained in that, for example, the hand rotates by 180° respectively when in one instance a glass shall be handled and in another instance a tool shall be inserted.  
         [0069]     In a preferred improvement of the inventive apparatus which may also be used alone, the robot has a gripper which grips the glasses at their periphery. In particular, this is effected with a predetermined force, wherein, further a force controller is preferably provided.  
         [0070]     These measures have the already mentioned advantage that the sensitive optical surface of the spectacle lens does not need to be touched during the gripping of the glasses.  
         [0071]     In this context it is particularly preferred when the gripper has three or more fingers arranged essentially parallel to each other and being adapted to be brought into engagement with the periphery of a glass.  
         [0072]     This measure has the advantage that according to the number and the positioning of the fingers a gripping function as well as a centering function may be executed, and that the number and type of fingers may be optimised, depending on whether the glasses to be handled have a circular or an elliptical periphery or are shaped generally otherwise.  
         [0073]     According to another preferred variant of this embodiment the fingers are provided with a soft envelope at their periphery.  
         [0074]     This measure has the advantage that a damage to the periphery of the glasses is avoided even when relatively high gripping forces are used.  
         [0075]     In another preferred embodiment of the invention that may likewise be used alone, for polishing a first surface of a glass a polishing tool is provided which, one the one hand is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface. Thereby, an element for generating the rotation and/or for feeding-in is configured hollow.  
         [0076]     This measure has the advantage that the masses which have to be moved during the polishing process, may be kept very small. When doing so, inertia is reduced and the polishing surface may particularly easily follow the surface of the glass to be polished, wherein only minimum forces have to be executed.  
         [0077]     Insofar it is particularly preferred when the element is a tube.  
         [0078]     This measure has the advantage that a very simple and low-cost element may be used.  
         [0079]     In a preferred improvement of this embodiment the tube is a polygonal tube being radially journalled by means of roller bearings.  
         [0080]     This measure has the advantage that the tube in its axial feeding direction is journalled almost free of friction because roller bearings prevent a radial movement of the polygonal tube at lowest possible friction.  
         [0081]     In a further preferred way the tube transmits a torque from a rotational drive to the polishing tool.  
         [0082]     For that purpose the tube may be configured as a polygonal tube, as already mentioned, or may be configured as a non-circular tube or as a tube having a spline tooth or the like.  
         [0083]     In another improvement of this embodiment the element is connected to a linear displacement unit by means of a spherically journalled, non torque-transmitting transmission element.  
         [0084]     This measure has the advantage that the axial feeding-in movement of the polishing tool may be executed independently from the transmission of torque for the rotational movement of the polishing tool. The elements required for the axial displacement are, therefore, decoupled from the transmission of torque and can be configured with low friction.  
         [0085]     Preferably, the linear displacement unit is configured as a piston-cylinder unit.  
         [0086]     This measure has the advantage that proven positioning and control elements can be used.  
         [0087]     In this context it is further preferred when the transmission element is a coupling rod being preferably journalled spherically at both ends.  
         [0088]     These measures have the advantage that the already mentioned no torque transmitting connection may be established, wherein the spherical joint, further, prevents that the piston becomes jammed within the cylinder as a consequence of an oblique position of the surface to be polished.  
         [0089]     In a further preferred embodiment of the invention which may also be used alone, for polishing a first surface of a glass a polishing tool is provided which, one the one hand is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface, wherein for feeding-in the second surface a piston-cylinder unit is provided, the piston-cylinder unit comprising a piston air-mounted within a cylinder.  
         [0090]     This measure has the advantage that a particularly low friction arrangement is obtained because the piston is guided within the cylinder via an air bearing. As a consequence the contact force of the polishing tool, i.e. the polishing force, may be set particularly sensibly.  
         [0091]     In this context it is particularly preferred when the cylinder is a glass cylinder, and that the piston is a graphite piston.  
         [0092]     This measure has the advantage that an optimum frictional matching is obtained which may be operated over wide temperature ranges.  
         [0093]     Further, a particularly good result is obtained in this context when the piston-cylinder unit is connected to a working reservoir containing compressed air and having a first predetermined volume, the piston defining a second predetermined volume within the cylinder between its extreme operational positions, the first volume being much bigger than the second volume, preferably at least 100 times, in particular at least 1,000 times as big as the second volume, and, mostly preferred, when the first volume is about 1 cm 3  and the second volume is about 3,000 cm 3 .  
         [0094]     This measure has the advantage that the system operates extremely linearly over the entire working stroke of the piston because the change in volume within the working cylinder is significantly smaller as compared to the volume within the pressure reservoir.  
         [0095]     In another preferred embodiment of the invention which may also be used alone, for polishing a first surface of a glass a polishing tool is provided which, one the one hand is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface, wherein for executing the feeding-in movement a transmission element is provided, the transmission element being linearly moved relative to a housing and protruding with a section from an end of the housing in an oscillating manner, a first bellows being arranged between the end and the section.  
         [0096]     This measure has the advantage that the transmission element, moved in oscillation, is best protected against the intrusion of dirt. This is of particular advantage for the present application because during the polishing of the surface of the glass a substantial soiling occurs such that the guiding of the oscillating transmission element could eventually become clogged with the wear of the polishing tools.  
         [0097]     In a particularly preferred practical example of this embodiment the section carries an annular flange, the first bellows connecting the flange with the end.  
         [0098]     This measure has the advantage that a particularly simple and mechanically reliable setup is obtained.  
         [0099]     In another preferred embodiment of the invention which may likewise be used alone, for polishing a first surface of a glass a polishing tool is provided which, one the one hand is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface, wherein for executing the feeding-in movement a transmission element is provided, the transmission element being linearly moved relative to a housing and protruding with a section from an end of the housing in an oscillating manner, the section being surrounded by a protective sleeve being connected to the housing.  
         [0100]     This measure has the advantage that an unintended damage to the oscillating protruding section of the transmission element is definitely prevented.  
         [0101]     If, in a preferred improvement of this embodiment the protective sleeve surrounds the first bellows, this protection function extends also to the first bellows.  
         [0102]     In still another embodiment of the invention that may likewise be used alone, for polishing a first surface of a glass a polishing tool is provided which, one the one hand is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface, wherein the polishing tool is pivotably journalled in a transmission element, the transmission element being movable in the feeding-in direction along an axis, a tumbling disk being provided, the tumbling disk being connected with the transmission element via a spherical joint, and the tumbling disk being adapted to be coupled to the polishing tool.  
         [0103]     This measure has the advantage that the spherically journalled tumbling disk enables in a particularly perfect manner to follow the different elevation of the surface to be polished of the glass. This holds true in particular in comparison to the gimballed suspensions of the prior art (U.S. Pat. No. 5,247,999) and, in particular, a bearing by means of a roller bellows (EP 0 567 894 A1), but also in comparison to a spherical Allen joint (WO 01/56740 A1, DE 101 00 860 A1).  
         [0104]     In connection with the afore-described embodiment of the invention it is preferred when the transmission element has a ball head as a terminal end, the polishing tool being provided with a ball socket, the polishing tool being elastically held on the transmission element, wherein the ball head is elastically held in the ball socket, such that the polishing tool can execute a tumbling movement relative to the transmission element.  
         [0105]     This measure has the advantage that, one the one hand, a tumbling movement of the polishing tool is possible and, on the other hand, by means of the elastic support the necessary torque can be transmitted to the polishing tool, while at the same time the spherical joint is held altogether with the necessary bearing force.  
         [0106]     In a preferred improvement of this embodiment, the transmission element has a finger as an axial terminal end, the ball head being arranged at a free end of the finger.  
         [0107]     This measure has the advantage that due to the cantilevered arrangement of the spherical joint consisting of the ball head and the ball socket a tumbling movement with a particularly large amplitude is enabled.  
         [0108]     Further, in this embodiment it is preferred when for elastically holding the polishing tool a second, torque-transmitting bellows is arranged between the transmission element and the polishing tool.  
         [0109]     This measure, on the one hand, has the advantage that the spherical joint in the above-described manner is also reliably protected against soiling as occurs during the polishing process; on the other hand, the elastic support and, thereby, the transmission of torque as well as the holding force within the spherical joint may be guaranteed with a particularly simple and low cost element, namely a bellows.  
         [0110]     This holds true in a preferred manner if the second bellows surrounds the finger.  
         [0111]     Finally it is preferred in this context if the ball socket is configured conical.  
         [0112]     This measure has the advantage that there only exists a very small contact surface between the ball head and the ball socket, ideally just a contact line, such that the joint has only a very low friction.  
         [0113]     In a preferred embodiment of the invention which may also be used alone, for polishing a first surface of a glass a polishing tool is provided, the polishing tool being coupled to a drive via a magnetic clutch.  
         [0114]     This measure has the advantage that no mechanical clutch has to be opened or closed for connecting the polishing tool with its drive. Instead, the magnetic clutch may be opened and closed in a simple manner. This may be done either electrically, or by separating the magnetically coupled elements from each other through the application of a pulling force.  
         [0115]     In a preferred improvement of this embodiment the magnetic clutch is provided with permanent magnets.  
         [0116]     This measure has the advantage that the clutch is operated without current. The permanent magnets may either be used as a pair of permanent magnets or as a permanent magnet together with a corresponding piece of soft iron.  
         [0117]     In this embodiment an example is further preferred in which the polishing tool, on the one hand, is tangentially guided with a second, rotating surface over the first surface, and, on the other hand, for compensating different elevations within the first surface is fed-in in a direction perpendicular to the first surface, wherein the polishing tool is pivotably journalled in a transmission element, the transmission element being movable in the feeding-in direction along an axis, a tumbling disk being provided, the tumbling disk being connected with the transmission element via a spherical joint, and the tumbling disk being adapted to be coupled to the polishing tool via a magnetic clutch.  
         [0118]     This measure has the advantage that in a practical embodiment the polishing tool may, in a most simple manner, be coupled to and decoupled from its corresponding drive unit, namely the tumbling disk, such that the polishing tool needs only to consist of a polishing disk and a polishing coating.  
         [0119]     Also in the afore-mentioned case it is preferred when the transmission element has a ball head as a terminal end, the polishing tool being provided with a ball socket, and the polishing tool being elastically held on the transmission element, wherein the ball head is elastically held in the ball socket, such that the polishing tool can execute a tumbling movement relative to the transmission element.  
         [0120]     In another group of embodiments of the invention that may likewise be used alone, a tool magazine is provided, a plurality of polishing tools being deposited in the tool magazine, the tool magazine being located within the operational area of a robot.  
         [0121]     This measure has the advantage that the tool change, in particular the polishing tool change, may be automated. In particular, a worn polishing tool may be exchanged against a fresh polishing tool. Further, it is possible for the subsequent processing of glasses of different size to change polishing tools in different sizes one after the other.  
         [0122]     In a preferred manner the tool magazine is configured with a plurality of chutes, the polishing tools being sorted and stored in the chutes according to the radii of their polishing surface.  
         [0123]     Further, it is preferred when the chutes are inclined relative to a horizontal plane, and when slideways for the polishing tools are provided.  
         [0124]     This measure has the advantage that the tools move up sliding in the chutes as soon as a tool is withdrawn at the lower end such that a new tool is automatically placed ready every time at a pickup position without the necessity of separate conveyor installations.  
         [0125]     In that case it is preferred when stops are provided at the lower end of the slideways.  
         [0126]     Further advantages of the invention will become apparent from the description and the appended drawing.  
         [0127]     It goes without saying that the features mentioned above and those that will be explained hereinafter may not only be used in the particularly given combination, but also in other combinations, or alone, without leaving the scope of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0128]     Embodiments of the invention are shown in the drawing and will be explained in the subsequent description.  
         [0129]      FIG. 1  shows a flow chart for explaining a method for producing optical glasses according to the prior art;  
         [0130]      FIG. 2  shows a flow chart, similar to  FIG. 1 , however, for an embodiment of a method according to the present invention;  
         [0131]      FIG. 3  shows a highly schematic top plan view of an embodiment of an apparatus according to the present invention;  
         [0132]      FIG. 4  shows a side elevational view along line IV-IV in  FIG. 3 ;  
         [0133]      FIG. 5  on a highly enlarged scale shows a side elevational view, partially cut away, of a hand of a robot, as may be used in an apparatus according to  FIGS. 3 and 4 ;  
         [0134]      FIG. 6  on a further enlarged scale shows a portion of the hand of  FIG. 5  for explaining further details;  
         [0135]      FIG. 7  on a further enlarged scale shows a detail from  FIG. 6  depicting an air cylinder;  
         [0136]      FIG. 8  on a further enlarged scale shows a detail illustration of  FIG. 6 , depicting a tumbling disk;  
         [0137]      FIG. 9  on a further enlarged scale shows a detail from  FIG. 6  depicting a polishing tool;  
         [0138]      FIGS. 10 and 11  show two perspective views of the elements tumbling disk and polishing tool depicted in  FIGS. 8 and 9 ;  
         [0139]      FIG. 12  shows a schematic side elevational view, partially cut away, of a gripper as may be used in the hand of the robot according to  FIG. 5 ;  
         [0140]      FIGS. 13 through 17  show schematic top plan views on the arrangement of  FIG. 12 , for five distinct embodiments;  
         [0141]      FIG. 18  shows a highly schematic side elevational view of a tool magazine as may be used with an apparatus according to  FIGS. 3 and 4 ;  
         [0142]      FIG. 19  shows a top plan view on the tool magazine according to  FIG. 18 ;  
         [0143]      FIG. 20  shows a sectional view along line XX-XX of  FIG. 19 ;  
         [0144]      FIG. 21  on a highly enlarged scale shows a top plan view on a glass being processed according to the method of the present invention; and  
         [0145]      FIG. 22  shows a detailed flow chart for explaining the process according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0146]     In  FIG. 1  reference numeral  10  as a whole indicates a flow chart for explaining a working process according to the prior art. After the lathing or the grinding of a spectacle lens (block  12 ) the spectacle lens as well as a polishing tool are manually fed to a polishing machine (block  14 ). The polishing machine then executes the polishing process (block  16 ). The polished spectacle lens is then unloaded and the polishing tool is removed (block  18 ).  
         [0147]     The spectacle lens must now be cleaned manually or by means of a special washing device (block  20 ), and the polishing tool and/or the washing tool must be reprocessed manually or by means of a special device (block  22 ). The spectacle lens is then manually fed to a marking station (block  24 ) and marked therein (block  26 ). Only then the spectacle lens may be unloaded by hand (block  28 ) and may be transported away.  
         [0148]     From the preceding description it becomes apparent that the conventional processes require a substantial amount of time because a large number of manual steps have to be executed which costs time on the one hand and may be a source of faults, on the other hand.  
         [0149]     In contrast thereto,  FIG. 2  shows a block diagram  30  which, in a conventional manner, follows the automatic shaping process of the spectacle lens by lathing or grinding (block  32 ), whereas thereafter all subsequent steps of polishing, cleaning and marking are executed fully automatically (block  34 ), without the necessity of manual intervention. This shall be described hereinafter:  
         [0150]     In  FIGS. 3 and 4  reference numeral  40  designates a processing cell having a housing frame  41 . The processes of polishing, washing and marking are executed fully automatically within processing cell  40 .  
         [0151]     The lenses are fed from a conventional lathing or grinding machine  42  to a conveyor belt  44  in the direction of an arrow  43 , where they are transported to processing cell  40  along a conveyor direction indicated by an arrow  46 .  
         [0152]     Transportation boxes  48  are used for transportation on conveyor belt  44 . Each of transportation boxes  48  receives one pair of lenses  50   a,    50   b,  being each allotted to a particular patient or customer. As will be explained further below ( FIG. 12 ), lenses  50  are arranged on a block  51 , as known per se, so that they may be easier held and moved (rotated) during processing.  
         [0153]     In the embodiment shown, four handling positions  52   a,    52   b,    52   c  and  52   d  are indicated on conveyor belt  44  within processing cell  40 . At these handling positions  52   a  through  52   d,  one transportation box  48  may be stopped at one time. This makes it possible to place lenses  50  ready in a predetermined position, so that lenses  50  from different transportation boxes  48  may be processed in parallel within different stations of processing cell  40 .  
         [0154]     Processing cell  40  comprises a polishing station  54 , a washing station  56 , a marking station  58  as well as a central control unit  60 . A robot  62  is provided within processing cell  40  as a central work unit. Robot  62  cooperates with a tool magazine  64 .  
         [0155]     Robot  60  is standing on a base  70 . Various possible movements of robot  60  are indicated by arrows  72  and  74 . In a preferred embodiment of the invention, robot  62  is a six-arm-robot.  
         [0156]     Robot  62  is provided with an arm  76  having a hand  78  at a free end thereof. Hand  78  is adapted to be rotated about an axis  80  extending along arm  76 , as indicated with another arrow  82 .  
         [0157]     Processing cell  40  operates as follows:  
         [0158]     At the beginning of a processing operation robot  62  is actuated such that a gripper arranged on arm  78  takes a lens  50  out of a transportation box  48 . Details of the gripper will be explained further below with regard to  FIGS. 5 and 12  through  17 .  
         [0159]     Robot  62  now transfers lens  50  to a polishing spindle  84  within polishing station  54 . Lens  50  with its block  51  is inserted into a socket of polishing spindle  84 , such that lens  50  may be rotated.  
         [0160]     After depositing lens  50  within polishing spindle  84 , robot  62  drives hand  78  to tool magazine  64 . There, polishing tools  88  are stored in chutes  86 . For example, polishing tools  88  of different size may be sorted in different chutes  86 . Further details of tool magazine  64  will be explained further below with regard to  FIGS. 18 through 20 .  
         [0161]     As polishing tools  88  are wearing parts requiring to be reprocessed after a polishing process, it is necessary to keep available a sufficient large number of polishing tools  88  within tool magazine  64 , for example as many polishing tools as are needed for a one day production.  
         [0162]     For receiving polishing tool  88 , hand  78  of robot  62  is rotated about axis  80  so that the respective polishing tool  88  may be received. Details thereof will be explained further below with regard to  FIGS. 5 through 11 .  
         [0163]     Robot  62  with polishing tool  88  arranged at hand  78  now returns to polishing station  84  and moves into a collar surrounding polishing spindle  88  until polishing tool  88  with its polishing surface comes into contact with the surface of lens  50  to be polished. Details of the polishing process will be described further below, in particular with regard to  FIG. 21 .  
         [0164]     As soon as the polishing process is completed, hand  78  with polishing tool  88  moves out of polishing spindle  84 . Polishing tool  88  is now transferred to a dumping magazine  90 . Here, polishing tool  88  is stripped from hand  78  by driving polishing tool  88  forward behind a cut-back stop and by then retracting hand  78  back from polishing tool  88 . Polishing tool  88  then falls into a container within dumping magazine  90  filled with a cleaning fluid.  
         [0165]     Robot  62  now returns with hand  78  to polishing station  54  and takes lens  50  having been polished but being soiled due to the preceding polishing process. It now transfers same to washing station  56 , namely into a holder  94  being located there.  
         [0166]     Robot  62  now separates with its hand  78  from lens  50  an picks up a sponge  98  arranged in a trough  96  of washing station  56  for cleaning polished lens  50  thereafter. For that purpose lens  50  may remain secured stationarily or may be moved within holder  94 .  
         [0167]     After the completion of the washing process sponge  98  is again deposited in a deposition unit  100  of trough  96 . Again, this may be effected by means of a cut-back stop and a stripping movement of the hand.  
         [0168]     For supporting the washing process a plurality of jets is provided, one of which being indicated at  102  in  FIG. 4 . A washing fluid, for example water, and subsequently a drying medium, for example compressed air, may be fed via jets  102 .  
         [0169]     After having deposited sponge  98  robot  62  with its hand  78  again moves to lens  50  having now been washed an dried and takes it from holder  94 . Robot  62  now transfers lens  50  to a marking holder  104  within marking station  58 . Lens  50  is marked there, for example by means of a laser, i.e. is provided with a certain product number, but may also be provided with marks on the optical surface allowing the optometrist at a later stage to exactly fit the spectacle lens into a spectacle frame.  
         [0170]     While within the polishing station as well as within the washing station, robot  62  actively participated in the processing steps of polishing and of washing executed therein, such activity is not required within marking station  58  because lens  50  was only deposited in marking holder  104 , whereas the marking itself is executed automatically and without the involvement of robot  62 .  
         [0171]     Considering that the marking process on the other hand side requires some time, robot  62 , in a preferred improvement of the invention, may already take the subsequent lens  50  from its transportation box  48  during that time and may execute the afore-described steps of polishing and of washing thereon. It may also be possible to likewise handle and process the next but one lens accordingly, until the marking on the first lens is completed whereupon it may be taken away from the marking holder by robot  62  and be laid back into its transportation box  48 .  
         [0172]     Transportation boxes  48  with the completely processed lenses  50  now leave processing cell  40  on conveyor band  44  in the direction of arrow  106  indicated in  FIG. 3 .  
         [0173]      FIGS. 5 through 17  show further details of elements arranged on hand  78 .  
         [0174]      FIG. 5  in a side elevational view shows the axis  80  of arm  76  extending perpendicular to  FIG. 6  as well as the pivotal movement of hand  78  by, preferably 180° each, indicated with arrow  82 . At this point it should be self-understanding that hand  78  may also be provided with a larger number of units at respective smaller angular increments.  
         [0175]     In the illustration of  FIG. 5 a  gripper  110  with a plurality of fingers  112  is arranged at the upper end of hand  78 . At the lower end of hand  78  a polishing head  114  together with a rotational drive  116  for polishing tool  88  as well as a piston-cylinder unit  118  for an axial displacement of polishing tool  88  along a longitudinal axis  120  are provided.  
         [0176]     Also at this point it goes without saying that the elements shown are to be understood only schematically and that of course other types of rotary drives or of linear drives may likewise be used.  
         [0177]      FIG. 6 , on an enlarged scale and with further details, shows the lower end of hand  78 . This lower end is entirely surrounded by a housing  128 .  
         [0178]     Within housing  128  and below rotary drive  116  there is arranged a first pinion  130  driven thereby, connected with a second pinion  132  via a toothed belt  134 , the second pinion  132  rotating about axis  120 . Second pinion  132  drives a rotor  136  being journalled via a plurality of bearings within a seat  137  being stationary with the housing.  
         [0179]     At its lower end rotor  136  is provided with a sleeve  138  in which a polygonal tube  140  is arranged non-rotatably but axially displaceable. Polygonal tube  140  is radially journalled within sleeve  138  via roller bearings  142 . As a consequence, polygonal tube  140  rotates with sleeve  138 , however, may axially move within sleeve  138  with almost no friction.  
         [0180]     Rotor  136  terminates downwardly in a lower end  142  and configures a radial closure plane there. A tapering section  145  of polygonal tube  140  extends through the closure plane and protrudes outwardly. At the free end thereof a tumbling disk  144  is arranged, further details of which being explained below with regard to  FIG. 8 .  
         [0181]     A first bellows  146  is attached with its upper rim to the lower end  143  of rotor  136  and with its lower rim to a flange  147  surrounding the lower portion of protruding section  145  of polygonal tube  140 . Thereby it is effected that during an axial movement of section  145 , within the opening defined by lower end  143 , no dirt may enter from outside into the area of the polygonal tube  140 , and, in particular, not into the area of roller bearings  142 .  
         [0182]     Finally, a surrounding protective sleeve  148  is arranged about first bellows  146 .  
         [0183]     Polygonal tube  140  may be displaced in the direction of axis  120  according to a predetermined force/displacement function. Piston-cylinder unit  118 , already mentioned, is used for that purpose.  
         [0184]     Piston-cylinder unit  118  is preferably operated pneumatically. For that purpose, a rotary compressed air junction  150  is provided at the upper end of piston-cylinder unit  118  allowing a compressed air supply to piston-cylinder unit  118  rotating during operation together with rotor  136 . A duct  152  connects rotary joint  150  to a compressed air reservoir  154 . In  FIG. 6 , the volume thereof is designated with V R  and its operating pressure with p R .  
         [0185]     Piston-cylinder unit  118  is provided with a so-called air cylinder  160 . As can particularly be seen from  FIG. 7 , air cylinder  160  is provided with a glass cylinder  162 , within which runs a piston  164  with minimum air gap  166 . An axial force-transmitting connection is established between piston  164  and an upper flange  172  of polygonal tube  140  via a coupling rod  168 , the upper and the lower end of which being provided with a ball head, the upper end being designated  170  in  FIG. 7 .  
         [0186]     In a practical embodiment piston  164  has a diameter of 16 mm and a stroke of 5 mm. The working volume of piston  164  between its extreme operational positions, designated V A  in  FIG. 7  is, therefore, about 1 cm 3 .  
         [0187]     Volume V R  of compressed air reservoir  154 , in contrast, is about 3,000 cm 3 , such that the ratio of the volumina in that case is 3,000:1. The operational pressure p R  is, for example, between 4 and 5 bar. Thereby, an operational force of piston  164  in the range of between 50 and 100 N is generated.  
         [0188]     Cylinder  162 , as already mentioned, preferably consists of glass. Piston  164  preferably consists of graphite, whereby an optimum frictional matching is generated, resulting in a minimum frictional coefficient over wide ranges of temperature. Due to the small air gap  166  an air bearing between piston  164  and cylinder  162  is configured, such that piston  164  runs within glass cylinder  162  with almost no friction.  
         [0189]     By means of rotary drive  116  a rotary movement of rotor  136  at, for example 1,000 min −1  is induced. In order to enable polishing tool  88  with the lower side of tumbling disk  144  to follow the change of elevation of lens  50  rotating at the same speed and, preferably, with the same direction of rotation, polishing tool  88  follows the rotating spectacle lens surface with a constant contact force at frequencies above 50 Hz.  
         [0190]     The low friction of the elements responsible for the linear drive together with the small weight, in particular that of hollow polygonal tube  140 , enables a precise position control at extremely small inertial forces.  
         [0191]      FIG. 8  shows further details of tumbling disk  144 .  
         [0192]     A lower end  180  of section  145  of polygonal tube  140  terminates in a first disk  182  which, as a clamping device, is provided with an upper plate  183   a  and a lower plate  183   b  which can be bolted together. An upper rim  184  of a second bellows  186  is clamped between these plates  183   a,    183   b,  the second bellows  186 , like first bellows  146 , being arranged rotationally symmetrical about axis  120 .  
         [0193]     A lower rim  188  of second bellows  186  is held in a second disk  190  which is likewise configured as a clamping device with an upper plate  191   a  and a lower plate  191   b.    
         [0194]     Second bellows  186  surrounds a spherical joint. The spherical joint is configured, on the one hand, by an axial finger  192  extending downwardly as an extension of lower end  180 , and having at its free end  180   a  ball head  194  with a center  196 .  
         [0195]     The counterpart of the spherical joint is configured by a conical opening  198  within upper plate  191   a  as well as a ball socket  200  within lower plate  191   b.  Ball socket  200 , preferably, is configured as a cone within an insert  202  within lower plate  191   b.    
         [0196]     As can easily be seen from  FIG. 8 , second disk  190  may execute a tumbling movement relative to first disk  182 , during which ball socket  200  is pivoted about ball head  194 .  
         [0197]     Second bellows  186 , insofar, has three functions:  
         [0198]     On the one hand, second bellows  186  is adapted to transmit a torque from polygonal tube  140  via the lower end  180  of the latter to second disk  190  to which polishing tool  88  is attached, as will still be explained.  
         [0199]     On the other hand, second bellows  186  generates an axially directed pulling force, pulling second disk  190  elastically upwardly, such that ball head  194  is elastically held within ball socket  200 . In such a way, second disk  190  may execute a tumbling movement relative to first disk  182  over a wide angular range.  
         [0200]     Finally, second bellows  186  acts as a protection of the spherical joint against being soiled.  
         [0201]     In order to be able to attach polishing tool  88  to tumbling disk  144  from below, the following measures have been taken:  
         [0202]     First, on the lower side of second disk  190  a pin  204  is provided protruding along axis  120  and being provided with a taper  206  at its lower end. Second, the lower side of second disk  190  is provided with three permanent magnets  208   a,    208   b,  and  208   c,  offset about 120° with respect to each other in a peripheral direction, as becomes particularly apparent from  FIG. 11 .  
         [0203]      FIG. 9  shows that polishing tool  88  has a third disk  210  being provided with an annular flange  211  at its periphery, as will be discussed below in connection with the explanation of the tool magazine ( FIGS. 18 through 20 ).  
         [0204]     Below third disk  210  there is an elastic layer  212 , preferably a soft sponge. The tool  214  as such is attached to the underside of layer  212  and is commonly referred to as polishing shell. The lower surface  216  thereof, constituting the polishing surface, is shaped convex in the embodiment shown in  FIG. 9  in order to polish concave lens surfaces. Of course, surface  216  may also be shaped convex for processing concave lens surfaces.  
         [0205]     A location hole  218  is located in the center of third disk  210 , hole  218  being complementary to pin  204  of tumbling disk  144 . In particular, hole  218  has an insertion taper at its upper end adapted to cooperate with taper  206  of pin  204 .  
         [0206]     Further, third plate  210  is likewise provided with three permanent magnets  222   a,    222   b, t   222   c  spaced by 180° with respect to each other, as can most clearly be seen in  FIG. 10 .  
         [0207]     As can be easily understood, polishing tool  88  may be simply connected with tumbling disk  144  by assembling axially the elements shown in  FIGS. 8 and 9 . Then pin  204  enters into hole  218  and magnets  208 / 222  attract each other and provide for the necessary holding force. In the illustrated embodiment, magnets  208 / 222 , further, are configured as catches, such that there is also a torque-transmitting connection between tumbling disk  144  and polishing tool  88  because magnets  222  enter into bores  224  into which magnets  208  are inserted.  
         [0208]     It should be clear at this point that permanent magnets  208 ,  222  are to be understood solely as examples. Electrically operated magnets or combinations of magnets and of soft iron parts could likewise be used with the same results.  
         [0209]      FIGS. 12 and 17  illustrate further details of gripper  110 .  
         [0210]      FIG. 12  shows that fingers  112  of gripper  110  consist of a core  230  and of an envelope  232 , wherein core  230  is configured mechanically stable and hard, whereas envelope  232 , preferably, is configured soft.  
         [0211]     It is important for gripper  110  that fingers  112  grip lens  50  solely at its periphery  236 , whereby, in contrast to the prior art, the optical surface of lens  50  remains untouched.  
         [0212]      FIG. 13  shows a configuration in which a lens being circular in a top plan view is held by four fingers  112   a  through  112   d  which, according to  FIG. 14  is also possible for a lens with an elliptical shape as seen from above.  
         [0213]     As illustrated by  FIGS. 15 and 16 , this is likewise possible if three fingers  112   a  through  112   c  are used.  
         [0214]     Finally,  FIG. 17  shows an irregularly shaped lens  50 ′, as seen from above, which may also be held by three fingers.  
         [0215]      FIGS. 18 through 20  illustrate further details of tool magazine  64 .  
         [0216]     Tool magazine  64  is provided with two parallel rails  240   a,    240   b  for each chute  86 . Rails  240   a,    240   b  are each provided with longitudinally extending slide grooves  242   a,    242   b  facing each other. At the left hand end of grooves  242   a,    242   b,  as seen in  FIGS. 18 and 19 , spring-biased pins  244   a,    244   b  are provided which, in their relaxed state extend into slide grooves  242   a,    242   b.    
         [0217]     Rails  240   a,    240   b  are arranged in an inclined orientation relative to a horizontal mount  246 , as indicated in  FIG. 18  by an angle α.  
         [0218]     Polishing tools  88  are held within rails  240   a,    240   b,  by letting above-mentioned annular flanges  211  of third disks  210  of polishing tools  88  run in slide grooves  242   a,    242   b  (cf.  FIG. 9 ). Under the action of gravity, polishing tools slide by themselves to the left hand end of rails  240   a,    240   b,  as seen in  FIG. 18 . The respective lowermost polishing tool  88  is retained there by means of spring-biased pins  244   a,    244   b.    
         [0219]     As can clearly be seen from  FIGS. 8 and 9 , second disk  190  at the lower end of tumbling disk  144  has a much smaller diameter as compared to third disk  210  at the upper side of polishing tool  88  which is also shown from above in  FIG. 19 . Robot  62 , therefore, in the operational position of  FIG. 5 , may move with its hand  78  into the area of tool magazine  64  and insert second disk  190  into the gap between rails  240   a  and  240   b  until second disk  190  comes to rest on third disk  210 , whereupon disks  190 ,  210  stick together under the action of magnets  208 ,  222 . Robot  62  may now displace hand  78  in an axial direction of the respective chute  86 , such that the respective foremost polishing tool overcomes the retaining force of spring-biased pins  244   a,    244   b  and is pulled out of slide grooves  242   a,    242   b.  Thereupon, under the action of gravity, the respective next polishing tool  88  moves up by sliding.  
         [0220]      FIG. 21  shows a spectacle lens surface  250  in the manner of a polar coordinate system. The principal axes are designated x and y.  
         [0221]     An arrow  252  indicates the direction or rotation of lens  50 , and, hence, of surface  250  when lens  50  is positioned within polishing spindle  84  of polishing station  54 .  
         [0222]     In  FIG. 21  surface  216  of polishing tool  88  is also shown as it rests on spectacle lens surface  250 . The center of surface  216  is designated  254 . Polishing surface  216  rotates in the same direction as spectacle lens surface  250  as indicated by an arrow  258 . The rotational speeds are likewise essentially the same.  
         [0223]     Reference numeral  256  in  FIG. 21  indicates a locus of movement of center  254  of polishing surface  216  during the inventive polishing process.  
         [0224]     As can clearly be seen, locus  256  is generated by the superimposition of two periodical movements. The first movement runs along a diameter  260  of spectacle lens surface  250 , i.e. in the y-direction in the illustration of  FIG. 21 . A second movement is superimposed on the first movement, wherein the second movement oscillates in the x-direction with small amplitude. The ratio between the frequencies of these movements in the y-direction and in the x-direction is 1:3 in the illustrated embodiment. Thus, a mirror-symmetrical undulated line instead of the straight line in equidistant distances according to the prior art.  
         [0225]     Finally,  FIG. 22  shows a third flow chart  270 , again illustrating the afore-described sequential steps within processing cell  40 . Accordingly, the lenses  50  arranged on blocks within transportation boxes  48  are processed according to the following scheme:  
         [0226]     if marking station  58  is not free, transport marked lens  50  back into its transportation box  48   
         [0227]     if washing station  56  is free, transport washed lens  50  into marking station  58   
         [0228]     if polishing station  54  is free, transport polished lens  50  into washing station  56   
         [0229]     if there is an unprocessed lens  50 , transport lens  50  into polishing station  54   
         [0230]     if there is a finished transportation box  48 , start conveyor belt  44   
         [0231]     if not, go to polishing  
         [0232]     if a transportation box  48  is found, then compute the polishing process as well as the polishing tool  88  individually for the right lens  50  and for the left lens  50  and check whether there is a polishing tool  88  within tool magazine  64   
         [0233]     if no new transportation box is found, activate the start function  
         [0234]     if start is pushed, then go to polishing  
         [0235]     if polishing station  54  is not free, polish lens  50  according to the computed program (getting polishing tool  88 , polishing, depositing polishing tool  88  in dumping magazine  90 )  
         [0236]     if marking station  58  is not free, then mark lens  50  according to the predetermined data  
         [0237]     after the polishing transport lens  50  into washing station  56   
         [0238]     wash lens  50   
         [0239]     go to program start.