Patent Application
20120205847
The present invention relates generally to a device for deblocking optical workpieces according the preamble portion of patent claim 1 as well as to such a method.
In the manufacture of optical products “block mounting” or, for short, “blocking” generally denotes the process in which an optical workpiece is temporarily fastened on a so-called “block piece” by means of a suitable material (low-melting-point alloy or adhesive) or, however, the blocking material is mounted on the workpiece in order itself to form the block piece, which then serves the purpose of holding the workpiece in the respective processing machine and/or coating installation. Correspondingly, in manufacture of optical products “deblocking” means that process in which the optical workpiece after processing and/or coating thereof is again separated from the block piece or blocking material.
The invention relates particularly to a device and a method for deblocking spectacle lenses. Spectacle lenses are blocked en masse in so-called “RX workshops” before the individual blocked spectacle lens is subjected, at its back or front surface with respect to its optical effect and/or at the edge for fitting in an associated spectacles frame, to machining by a geometrically defined cutter (milling/turning) or geometrically undefined cutter (grinding/polishing) and/or is coated on its back or front surface in order to achieve additional effects (increase in scratch resistance, anti-reflection properties, vapor deposition, hydrophobic characteristics, etc.).
If in the following reference is generally made in connection with the present invention to “spectacle lenses” as preferred field of use then there are to be understood by that optical lenses or lens blanks for spectacles from customary materials, such as polycarbonate, mineral glass, CR 39, HI Index, etc., and with any (start) shape of the circumferential edge of the lens or the lens blank, which prior to blocking can already have been—but does not have to be—subjected to (pre-) processing and/or (pre-) coating at one optically effective surface or both optically effective surfaces and/or at the edge. In addition, the spectacle lens can be provided on its surface at which it is or will be blocked with a film, a lacquer or the like in order to protect this surface from contamination and damage and/or to improve the adhesion characteristics between spectacle lens and blocking material, without this actually being specified hereinbelow.
There is no lack of proposals in the prior art with regard to how a device for automated deblocking of spectacle lenses can be constructed, in which connection a pressure medium such as water is employed in order to detach the spectacle lens from the block piece by application of hydraulic force and, in particular, either from “inside” by way of a pressure medium channel in the block piece, which opens at the blocking surface of the block piece facing the spectacle lens (e.g. DE 10 2005 038 063 A1, FIG. 13; WO 03/018253 A1, FIG. 4) or from “outside” by means of a high-pressure water jet which is issued by a nozzle and which impinges on an edge location between block piece and spectacle lens (for example WO 2008/003805 A1, FIG. 1).
A disadvantage of the “inside” application of the hydraulic forces is to be seen in that the block piece is provided with cavities which are open towards the blocking surface and which stand in the way of a desirable whole-area support of the spectacle lens at the block piece. In principle, the opening in the blocking surface can indeed be reduced in order to achieve an approximately whole-area support, but then it is barely possible to apply the hydraulic forces in order to separate the spectacle lens from the block piece.
Help can admittedly be created here through the use of a small piston in the (separate) block piece, which adjoins the blocking surface, as proposed as an alternative in WO 03/018253 A1 (FIGS. 14 to 22). However, during the deblocking mechanical forces are then applied by way of this piston to a relatively small central area at the spectacle lens, which can have the consequence of destroying the spectacle lens. It is at least necessary for the detaching to generate forces which are higher than the adhesion forces between spectacle lens and block piece. In the case of the afore-described piston solution the separating forces act on the center of the spectacle lens, whereas the adhesion forces primarily act in an annular zone at the spectacle lens edge. Particularly in the case of thin spectacle lens this can have the consequence of comparatively strong deformations and high levels of stress in the spectacle lens to be deblocked, which ultimately can produce fracture of the spectacle lens, quite apart from the outlay involved in providing such a piston in the block piece.
The previously known “outside” solution according to WO 2008/003805 A1, which forms the preamble portion of claim 1, does indeed enable whole-area support of the spectacle lens at the block piece and additionally reduces the risk of damage of the spectacle lens during deblocking. However, this prior art is in need of improvement in another respect.
The deblocking method disclosed there was developed specifically for deblocking spectacle lenses blocked by a thermoplastic blocking material. In that case melting of the blocking material is initially imposed by immersing the composite of spectacle lens, blocking material and block piece in a bath with hot water. Block piece and blocking material as well as a protective film on the spectacle lens are then detached from the spectacle lens by means of a high-pressure water jet. For that purpose the water for the jet is heated to a temperature of between 50° C. and 65° C. in order to re-soften the blocking material and ultimately liquefy it as a consequence of the heating. The high-pressure water jet here fans out relatively widely and is in addition rotated about the longitudinal axis of the nozzle in order to also pass under the protective foil on the rotating spectacle lens and lift this off the spectacle lens.
A disadvantage of this prior art is to be seen particularly in that—also a consequence of the intermediate preheating step in the hot water bath—the deblocking of a spectacle lens lasts for a relatively long time, which represents an obstacle to efficient use of this method in RX workshops.
The invention has the object of creating a device for deblocking optical workpieces, particularly spectacle lenses, by means of which the optical workpieces can be deblocked as safely, free of damage and rapidly as possible. The object of the invention additionally embraces provision of a corresponding deblocking method.
This object is fulfilled by the features indicated in claim 1 or 13. Advantageous or expedient developments of the invention form the subject of claims 2 to 12 and 14 to 21.
According to the invention in the case of a device for deblocking optical workpieces, particularly spectacle lenses, which comprises a first movement device for rotating a workpiece, which is blocked on a block piece, about a workpiece axis of rotation, a nozzle subassembly with a nozzle for delivery of a high-pressure jet of pressure medium in a direction substantially transverse to the axis of rotation of the workpiece onto an edge region between workpiece and block piece and a second movement device for producing a relative movement between the workpiece and a nozzle along the axis of rotation of the workpiece, the workpiece is displaceable with respect to the nozzle or conversely the nozzle is displaceable with respect to the workpiece by means of the second movement device along the axis of rotation of the workpiece with positional regulation (Y-axis) so that the high-pressure jet of pressure medium can be oriented to a predetermined place of incidence in the edge region between workpiece and block piece.
In terms of method, the invention provides deblocking of optical workpieces, particularly spectacle lenses, with use of the device according to the invention by the following steps:
Due to the fact that the high-pressure jet of pressure medium by contrast with the prior art defining the category is no longer incident or incident less by chance on the separating point between block piece and blocking material or the separating point between blocking material and workpiece, but as a consequence of the relative (height) adjustability of nozzle and block piece can be directed selectively onto the respective separating point with CNC technology it is possible to significantly more quickly deblock the workpiece, which predestines the device/method according to the invention particularly for use in RX workshops. In this regard, a rapid deblocking process can be beneficially operated with a relatively high pressure of the pressure medium without a risk of the workpiece being damaged by the high-pressure jet of pressure medium, because due to the capability of selective movement to the relative setting of nozzle and block piece or workpiece it is possible to avoid scanning of the workpiece in a critical manner by the high-pressure jet of pressure medium. Thus, workpieces blocked by, in particular, adhesives can be deblocked rapidly, safely and free of damage without needing advance soaking and/or softening procedures and/or temperature-controlled pressure medium for the deblocking.
For concrete realization of the above deblocking method in an automated sequence it is preferable if the steps (ii) and (iii) include calculation or setting (Y-axis) of a height position of the nozzle with respect to a reference point, which is already known from the blocking process, at the block piece in order to aim with the nozzle at the predetermined place of incidence in the edge region between workpiece and block piece. A special measurement of the blocked workpiece or the like for determination of the separating locations to be targeted by the high-pressure jet of pressure medium is thus superfluous.
If a layer of blocking material is present between the workpiece and the block piece the predetermined place of incidence of the high-pressure jet of pressure medium can in principle lie at the separating point between workpiece and blocking material. However, it is preferable if the predetermined place of incidence of the high-pressure jet of pressure medium lies in the boundary region between block piece and blocking material, since mathematical calculation of the height position of the nozzle with respect to the block piece is simpler than with respect to the workpiece, which can also be “three-dimensionally” blocked on the block piece, for example with prismatic displacement.
The first movement device is preferably a motor spindle comprising a collet chuck for reception, with orientation with respect to rotational angle, of the block piece, wherein the collet chuck is drivable to rotate about the axis of rotation of the workpiece by means of the motor spindle with rotational angle regulation (B axis). On the one hand, (at least) in the above step (iv) the block piece can thus be rotated by means of the first movement device about the axis of rotation of the workpiece, which accelerates the deblocking process by comparison with a—basically still possible—deblocking process with block piece held to be secure against rotation. On the other hand, it is thus possible in the above step (iv) to additionally calculate the height position of the nozzle with respect to the reference point at the block piece in dependence on the respective angular position of the block piece and to set or adjust it by means of the second movement device (Y-axis) so that the high-pressure jet of pressure medium is incident, not just at the start of the actual deblocking, but constantly in the boundary region between block piece and blocking material, this being a measure which further increases the precision and speed of the deblocking.
In a more advantageous and economic embodiment of the deblocking device the second movement device can comprise a Y-carriage which is displaceable by means of a servomotor and a threaded drive along the axis of rotation of the workpiece with positional regulation (Y-axis) and which carries the first movement device, i.e. the motor spindle.
In further pursuance of the concept of the invention a third movement device can be provided for producing a positionally regulated (X-axis) relative movement between the workpiece and the nozzle in a direction substantially perpendicular to the axis of rotation of the workpiece, wherein a clear spacing is settable between the nozzle and the predetermined place of incidence of the high-pressure jet of pressure medium by means of the third movement device. Thus, the spacing of nozzle and place of incidence can be optimized in simple manner with respect to a best possible (i.e. fast and reliable) deblocking result. The third movement device can—again in a more advantageous and economic embodiment—comprise an X-carriage which is displaceable by means of a servomotor and a threaded drive substantially perpendicularly to the axis of rotation of the workpiece with positional regulation (X-axis) and which carries the nozzle.
Thus, in an automated sequence of the deblocking method the steps (ii) and (iii) can further include calculation, or a setting (X-axis) carried out by means of the third movement device, of a radial position of the nozzle with respect to the reference point at the block piece in order to space the nozzle in defined manner from the predetermined place of incidence in the edge region between workpiece and block piece.
It is also possible in this case to additionally calculate the radial position of the nozzle with respect to the reference point at the block piece in dependence on the respective angular position of the rotating block piece in the above step (iv) and to set or adjust it by means of the third movement device (X-axis) so that the high-pressure jet or pressure medium after leaving the nozzle always impinges on the place of incidence in the edge region between workpiece and block piece after covering a substantially constant path (clear spacing).
Tests carried out by the applicant with a fan nozzle, which is available on the market and has a nozzle opening cross-section of approximately 0.45 millimeters and a jet angle of approximately 25°, in which tests were undertaken with a pressure-medium high-pressure jet—formed from non-temperature-controlled tap water as pressure medium—and with a water pressure between 100 and 140 bars, preferably 120 bars, have in this connection shown that the clear spacing between the nozzle and the predetermined place of incidence of the high-pressure jet of pressure medium should lie between 15 millimeters and 40 millimeters, preferably at approximately 20 millimeters, in order to achieve a certain and rapid deblocking process. If the clear spacing is here too small, the blocking material is detached only in the center of the fanned-out high-pressure jet, whereagainst if the clear spacing is selected to be too large, this substantially increases the deblocking time.
In a further advantageous embodiment of the deblocking device the nozzle can be mounted on a pivot bearing of the nozzle subassembly to be pivotable about an angle setting axis so that a setting angle of the nozzle with respect to a plane perpendicular to the axis of rotation of the workpiece is adjustable. The tests carried out have here shown that the setting angle of the nozzle with respect to the plane perpendicular to the axis of rotation of the workpiece should lie between 5° and 25°, preferably at approximately 15°. In this regard, the high-pressure jet can either be inclined in the direction of the block piece, which enables deblocking even of workpieces having a smaller diameter than the block piece, or, however, inclined away from the block piece, which during deblocking generates at the workpiece a force component which is directed away from the block piece and to that extent promotes separation of workpiece and block piece.
It is further preferred if the deblocking devices comprises a suction device with a suction head which serves the purpose of holding the workpiece, during deblocking from the block piece, at its second optically effective surface facing away from the block piece. The suction head of the suction device can thus hold the workpiece at least in the above steps (iv) and (v), which further reduces the risk of damage of the workpiece during deblocking.
If, in addition, in a further advantageous embodiment of the deblocking device the suction head aligned with the axis of rotation of the workpiece is movable by a piston-cylinder arrangement in the direction of the axis of rotation of the workpiece (linear movement Y′), so that in the above step (iv) it is ultimately possible to still apply to the workpiece by means of the piston-cylinder arrangement via the suction head sucking the second optically effective surface during the deblocking a predetermined pulling force which advantageously is only slightly smaller than the retaining force produced at the workpiece by the suction head, this similarly being beneficial for a rapid deblocking process.
The invention is explained in the following by way of preferred exemplifying embodiments with reference to the accompanying schematic drawings, wherein the same or corresponding subassemblies or parts are provided with the same reference numerals and further, for the sake of simplification of the illustration and enhanced clarity, subassemblies and parts not appearing necessary for an understanding of the invention were also omitted (such as control unit and control, casing parts, supply devices, inclusive of lines, hoses and pipes for current, compressed air and vacuum, etc.). In the drawings:
In the first embodiment according to
The deblocking device 10 is assembled as a whole on a base plate 18. Initially, a bracket 20 of the second movement device 16 is fastened on the base plate 18. A Y-carriage 22 (workpiece carriage) of the second movement device 16 is mounted on the bracket 20 by way of two linear guides 24, which are arranged parallelly and at a spacing from one another in transverse direction with respect to the axis B of workpiece rotation, to be longitudinally displaceable. Each linear guide 24 consists, in a manner known per se, of a guide rail or guide rod at one part (bracket 20 or Y-carriage 22) and associated guide shoes at the other part. In order to generate the linear movement along the axis B of workpiece rotation, i.e. in the direction Y, the second movement device 16 comprises a servomotor 26 which is operatively connected with the Y-carriage 22 by way of a threaded drive 28. Arranged laterally of the Y-carriage 22 (at the left in
As
In
Whereas the spectacle lens L is blocked by its first optically effective surface cx by means of the blocking material M on the block piece S, as is explained in more detail with reference to
The suction head 52 is fastened to a piston rod 54, which has a through bore, of a piston-cylinder arrangement 56, which is similarly mounted on the base plate 18 and by means of which the suction head 52 is movable in the direction of the axis B of workpiece rotation (linear movement Y′), i.e. selectably to the left or the right in
Before, in particular, the geometric relationship between nozzle D and block piece S in the deblocking device 10 and the function of the deblocking device 10 for the first and second embodiments are described together in more detail with reference to
The significant difference consists here in that in the case of the second embodiment illustrated in
In addition, the third movement device 64 has a bracket 66 which is attached to the base plate 18. An X-carriage 68 (nozzle carriage) of the third movement device 64 is mounted on the bracket 66 by way of two linear guides 70, which are arranged in parallel and spaced from one another in height direction in
A blank of, for example, plastics material for a spectacle lens L, which is still not processed at its second optically effective surface cc or at its edge surface R and which is blocked by its first optically effective surface cx on the blocking surface F of the block piece S by means of the blocking material M, is now shown in the upper part of
The block piece S is illustrated in the upper part of
The blocked spectacle lens L is shown in the lower part of
As can be inferred from, in particular, the plan view of
In addition, the relative position of the nozzle D with respect to the blocked spectacle lens L during deblocking of the spectacle lens L from the block piece S can be inferred from the lower part of
The relative position of nozzle D and blocked spectacle lens L in the deblocking device 10 is now defined by the adjustment angle or setting angle α of the nozzle D, i.e. of the pressure-medium high-pressure jet HDS, which it issues, with respect to a plane perpendicular to the axis B of workpiece rotation, the (radial) spacing xd of the outlet opening of the nozzle d from the reference point REF at the block piece S in X-direction and the (height) spacing yd of the outlet opening of the nozzle D from the reference point REF at the block piece S in Y-direction.
The setting angle α of the nozzle D should be fixedly preset to lie between 5° and 25°, wherein a smaller angle is better for flat curves (=larger radius r of the blocking surface F) and a larger angle for steep curves (=smaller radius r of the blocking surface F). The setting angle α of the nozzle D is preferably approximately 15°, which in tests carried out by the applicant proved to be a good compromise for a typical curve range.
The radial spacing xd of the outlet opening of the nozzle D from the axis B of workpiece rotation can be fixedly preset, as in the case of the first embodiment according to
If the high-pressure jet HDS of pressure medium is in terms of height incident in the boundary region between block piece S and blocking material M at the edge of the composite of spectacle lens L, blocking material M and block piece S, which is preferred, then the relative Y-position of the nozzle D (spacing yd) with respect to the reference point REF at the block piece S can, for a fixed relative X-position of the nozzle D (constant spacing xd), be calculated in accordance with the following equations:
y
d
=r−√{square root over (r2−re2)}+e+tan α·(xd−re),
with the ellipse radius re of
If, thereagainst, an adjustment possibility in the direction X is also provided as in the case of the second embodiment according to
x
d
=r
e
+Δx
d,
wherein
Δxd=ad·cos α,
and
y
d
=r−√{square root over (r2−re2)}e+tan α·Δxd.
In principle, it is possible to calculate the relative nozzle position (yd and optionally xd) prior to the actual deblocking process (1.) for a given angle position (BAX) of the spectacle lens L or of the block piece S with respect to the axis B of workpiece rotation in accordance with the above equations, (2.) to move up through CNC technology by adjustment in the Y-axis and optionally the X-axis, and maintain this during the actual deblocking process (3.), wherein then the block piece S with the spectacle lens L is rotated about the axis B of workpiece rotation. However, it is preferred to change the relative nozzle position (yd and optionally xd) during the actual deblocking process (3.′) in dependence on the respective angular position (BAX) of the spectacle lens L or block piece S with respect to the axis B of workpiece rotation and, in particular, by CNC technology movement in the Y-axis and optionally the X-axis during rotation of the spectacle lens L, so that as a consequence of co-ordinated movement in the B-axis, Y-axis and optionally X-axis the high-pressure jet HDS of pressure medium is always incident in terms of height in the boundary region between block piece S and blocking material M [i.e: yd=f(BAX)] after covering the optionally always constant path ad from the outlet opening of the nozzle D to the point MAP of incidence [optionally: xd=f(BAX)].
Particularly in the case of in puncto deblocking speed good results were achieved in tests performed by the applicant with use of a market-available fan nozzle of the company Kärcher, which had a nozzle opening cross-section q of approximately 0.45 millimeters and a jet angle β of approximately 25°, with use as pressure medium of tap water without temperature control and with a water pressure of between 100 and 140 bars, preferably 120 bars. In this regard the fan nozzle was so mounted with respect to its rotational angle orientation about the longitudinal axis thereof that, as can be seen at the bottom in
The principal steps of a deblocking method, which was carried out with the afore-described deblocking device 10 (first or second embodiment) for spectacle lenses L can now be summarized as follows:
Bearing in mind the above explanations with respect to
In the second embodiment according to
If in addition the block piece S is also rotated about the axis B of workpiece rotation by means of the first movement device (motor spindle 12) at least in step (iv) then it is preferred if in addition in step (iv) the height position yd of the nozzle D with respect to the reference point REF at the block piece S is calculated in dependence on the respective angular position BAX of the block piece S as described above and set or adjusted by means of the second movement device 16 (Y-axis) [i.e: yd=f(BAX)], so that the high-pressure jet HDS of pressure medium always impinges in the boundary region between block piece S and blocking material M. This again relates to both embodiments.
In the second embodiment according to
If designed with further sub-steps, the entire deblocking process can be represented in a semi-automatic sequence as follows: Initially, a “job ticket” or a code provided at the block piece S (“data matrix”; not shown) is scanned in at the blocking device 10 in order to call up the processing parameters or the block piece state, comprising, in particular, the radius r of the blocking surface F of the respective block piece S and the height e thereof referred to the reference point REF, and in addition the geometry data of the processed, blocked spectacle lens L, which data are required for calculation of the ellipse radius re if the block piece S was machined at the edge so that the edge of the block piece S differs from the original circular form with known diameter, namely the ellipse axes d and n as well as the angle GAX. The blocked spectacle lens is then placed in the deblocking device 10, i.e. clamped by means of the block piece S at the collet chuck 36 of the motor spindle 12.
After pressing the start button (not illustrated) an automatic step sequence then begins in which initially the door (not shown) of the deblocking device 10 is closed. The axis Y and optionally axis X then move into the calculated (start) position or positions as described above, whereupon the piston-cylinder arrangement 56 advances, i.e. the suction head 52 of the suction device 50 displaces in direction Y′ to the left in
Subsequently, a sub-atmospheric pressure is applied to the suction head 52 by way of the vacuum connection 62 so that the head firmly sucks the spectacle lens L. The piston-cylinder arrangement 56 is thereupon acted on pneumatically in such a manner that the piston 58 thereof seeks to draw the suction head 52 in the direction Y′ to the right away from the spectacle lens L by way of the piston rod 54 in
The high-pressure jet HDS is then switched on, whilst the spectacle lens OL is preferably rotated by way of the block piece S by means of the motor spindle 12. In order to follow this rotation the suction head 52 is equipped with an appropriate free running (not illustrated) with respect to the piston rod 54. As already described, the relative position between block piece S and nozzle D can now be set or adjusted by means of the second movement device 16 and optionally the third movement device 64 with rotational angle dependence in Y or X direction with the object of directing the high-pressure jet HDS always between the blocking material M and block piece S (Y-axis) and thereby optionally keeping the free jet length (clear spacing ad) of the high-pressure jet HDS constant (X-axis).
If, as a consequence of the superimposed action of high-pressure jet HDS and pulling force at the spectacle lens L, the spectacle lens L with the blocking material M now separates from the block piece S then the piston rod 54 and thus the piston 58 of the piston-cylinder arrangement 56 can move further to the right in
The high-pressure jet HDS is then switched off and the axes (Y and optionally X) move back to their starting position. The door of the deblocking device 10 opens and spectacle lens L and block piece S can be removed separately. The blocking material M still adhering to the spectacle lens L can now be removed by hand from the first optically effective surface cx of the spectacle lens L. However, as an alternative thereto use can also be made of a further, rotating high-pressure jet in the deblocking device, which jet is issued by a nozzle (not illustrated), which is individually provided for that purpose, in order to “peel off” the blocking material from the spectacle lens.
Finally, a decision is still to be taken whether the block piece S after appropriate cleaning can be reused or, however, has to be discarded if, for example, it was machined at the edge.
A deblocking device and an associated method for deblocking optical workpieces, particularly spectacle lenses, have been disclosed. The deblocking device comprises a first movement device for rotating a workpiece, which is blocked on a block piece, about an axis of workpiece rotation, a nozzle subassembly with a nozzle for issuing a high-pressure jet of pressure medium in a direction substantially transverse to the axis of workpiece rotation onto an edge region between workpiece and block piece and a second movement device for generating a relative movement between the workpiece and the nozzle along the axis of workpiece rotation. A feature of the deblocking device is that the workpiece is preferably displaceable with respect to the nozzle by means of the second movement device along the axis of workpiece rotation with positional regulation (Y-axis) so that the high-pressure jet of pressure medium can be directed onto a specific place of incidence in the edge region between workpiece and block piece, particularly to accelerate deblocking.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 048 590.2 | Oct 2009 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/005006 | 8/14/2010 | WO | 00 | 5/3/2012 |
