EP2014412B1 - Polishing disc for a tool for fine processing of optically active surfaces of in particular spectacle lenses and method for its production - Google Patents

Abstract

A polishing plate (10) has a basic body (14) provided with a central axle, and on which is fixed a soft, in relation to the basic body, intermediate layer having a polishing medium carrier (18). The intermediate layer has a radial inner zone (20) of mainly constant thickness and a radially outer zone connected thereto, whose radially outer dimensions starting from the basic body (14) to the carrier (18) increase, so that the elastic support of the polymer medium carrier by the intermediate layer (16) reduces in its radial outer zone to the outer edge (76) to the polymer media carrier. Independent claims are given for the following: (1) (A) A fine processing tool for optically effective surfaces. (2) (B) A method for fabricating a polishing plate.

Description

The present invention relates to a polishing plate for a tool for fine machining of optically active surfaces, according to the preamble of claim 1. Such polishing plates are used in particular in the production of prescription eyeglass lenses in bulk. Furthermore, the invention relates to a method for producing such a polishing plate, according to the patent claim 9.

If the following example of workpieces with optically active surfaces of "lenses" is mentioned, including not only eyeglass lenses made of mineral glass, but also eyeglass lenses from all other common materials, such as polycarbonate, CR 39, HI index, etc., including plastic be understood.

STATE OF THE ART

The machining of the optically effective surfaces of spectacle lenses can be roughly subdivided into two processing phases, namely first the pre-processing of the optically effective surface to produce the recipe macrogeometry and then the fine processing of the optically effective surface to eliminate Vorbearbeitungsspuren and obtain the desired microgeometry. While the preprocessing of the optically effective surfaces of spectacle lenses takes place, inter alia, as a function of the material of the spectacle lenses by grinding, milling and / or turning, the optically effective surfaces of spectacle lenses become during fine machining usually subjected to a fine grinding, lapping and / or polishing process.

For this finishing process in the prior art (see, for example, the DE-A-10 2005 010 583 ) increasingly adaptable - in contrast to rigid - used polishing plates having an at least three-layer or -lagigen structure, with (1) one of the tool spindle facing, solid or rigid support body, on the (2.) a softer contrast Layer, for example, a foam layer is attached, the (3.) a workpiece facing abrasive or polishing foil rests as a processing active tool component. Due to the elastic deformability of the foam layer, the polishing film can be adapted within certain limits to the geometry of the surface to be machined, both from "spectacle" to spectacle glass, which is to be processed, as well as in "dynamic" terms, ie during the processing of a specific spectacle lens, in which a relative movement between the polishing plate and the spectacle lens takes place. In addition, the elasticity of the foam layer significantly influences the removal behavior of the polishing plate during the polishing process.

When using such polishing plate with a polishing foil, which ends at the edge of the outer edge of the foam layer, it has been shown that it can come to a working of the polishing foil edge or the edge formed by this edge in the machined surface of the spectacle lens. This may result in visible, hence undesirable, "impressions" of the polishing foil edge, i. lead very fine, scratch-like microstructures on the optically effective surface of the lens.

To address this problem, it has already been proposed to dimension the polishing film so that it projects beyond the outer periphery of the foam layer to the outside (see Fig. 1 and 4 of the DE-A-10 2005 010 583 ). In this case, no significant polishing pressure can be exerted on the surface to be processed over the outer edge of the polishing film. Investigations by the applicant have shown, however, that this measure alone does not bring the desired success in all cases.

Furthermore, the disclosure EP-B-1 711 311 a polishing plate with three-layer or -lagigem structure in which the middle, elastic layer in the radial direction from the inside to the outside is increasingly softened to polish lenses with irregularly curved freeform surfaces in a surface quality that should make post-processing unnecessary. This outwardly increasingly softer formation is achieved in particular by the fact that the middle layer in the radial direction, ie from the inside to the outside has an increasing axial thickness, wherein the carrier body, the middle layer and the polishing foil ends together on a cylindrical outer peripheral surface of the polishing plate. However, unwanted "marks" of the polishing plate on the machined surface produced by the edge of the polishing film are not addressed in this prior art.

A polishing plate according to the preamble of claim 1 is finally from the US-A-6,371,837 known.

TASK

The invention has for its object to provide a polishing pad as simple as possible for a tool for fine machining of optically active surfaces on particular eyeglass lenses, the edges of which does not reflect on the machined surface in the form of microstructures. The invention also includes the provision of a method for the simple production of such a polishing plate.

PRESENTATION OF THE INVENTION

This object is achieved by the features specified in claim 1 and 9, respectively. Advantageous or expedient developments of the invention are subject matter of the claims 2 to 8 or 10 to 12.

According to the invention, in a polishing plate for a tool for fine machining of optically effective surfaces, in particular spectacle lenses having a central body having a central axis, to which a softer intermediate layer is attached in relation to the main body, which rests on a polish carrier, wherein the intermediate layer based on the central axis has a radially inner region of substantially constant axial thickness and an adjoining, radially outer region whose radial outer dimensions increase starting from the main body to the polish carrier, so that the elastic support of the polish carrier by means of the intermediate layer in the radially outer region Outer edge of the polishing medium carrier decreases, and wherein the polishing medium carrier is provided in a central region with at least one opening and at the at least one opening in the polish carrier in the direction of Grundk örpers connects a recess in the intermediate layer; the diameter of the recess in the intermediate layer, starting from the opening in the polish carrier to the base towards.

According to a second aspect of the invention comprises in a polishing plate for a tool for fine machining of optically active surfaces on in particular spectacle lenses having a central axis having base body to which a softer relative to the base body intermediate layer is fixed, which rests a polishing agent, the intermediate layer with respect to the central axis, a radially inner region of substantially constant axial thickness and an adjoining radially outer region, wherein the outer edge of the polishing medium carrier is held spaced apart from the latter by means of the radially outer region of the intermediate layer during the finishing of the optically effective surface.

Accordingly, in the polishing plate according to the invention, the intermediate layer is divided functionally into a radially inner region of substantially constant axial thickness and an adjoining, radially outer region, which has the task to prevent the edge of the polishing plate on the machined surface in Form of microstructures depicts. Since the inner region has a substantially constant axial thickness, the elasticity or resilience of the polishing plate does not change seen here over the radius, in contrast to the prior art according to FIG EP-B-1 711 311 , This results in a suitable relative movement between the tool and the workpiece advantageously a uniform polishing removal achieved - Preston's hypothesis: the polishing removal is proportional to the product of polishing pressure and relative speed between the tool and workpiece - so that the workpiece with high topographical fidelity, that can be polished shape preserving. In the edge region of the polishing plate, in which the radially outer region of the intermediate layer is located, the polishing removal decreases as a result of decreasing elastic support of the polishing medium carrier and thus also the possibility that the edge of the polishing plate on the machined surface "push" or can image.

In the edge region of the polishing plate in which the radially outer region of the intermediate layer is, the latter also ensures that the over radially inner region of the intermediate layer radially outwardly projecting outer edge of the polishing medium carrier is attenuated in its movements, in the fine machining of the optically active surface therefore not swing freely or flutter and thus can not hit the machined surface so that it is reflected there.

Furthermore, in the polishing plate according to the invention, the polishing agent carrier is provided in a middle region with at least one opening. This opening in the polish carrier provides fluid communication between an interior region of the foam usually comprised of a sponge-like liquid pad soaked with liquid polish and the outer surface of the polish carrier in machining engagement with the workpiece surface to be machined. Thus, the liquid polishing agent can circulate better and also pass from the interior of the polishing pad to the engagement areas between the polishing medium carrier and the surface of the workpiece to be machined, whereby at these engagement areas due to increased wetting of the polishing medium carrier or a more uniform polishing agent film on this better rinsing and Cooling is ensured. Accordingly, it may not come to partial, the surface quality produced detrimental solidification of the polish carrier. In addition, the opening in the Poliermittelträger advantageous for a relief of the resulting by deformation of the intermediate layer in this hydraulic pressure, which could otherwise lead to about a partial destruction of the intermediate layer, as well as for an "internal cooling" of the polishing plate.

Furthermore, a recess in the intermediate layer adjoins the at least one opening in the polishing agent carrier in the direction of the base body. The recess advantageously serves as a reservoir for the liquid polishing agent.

Finally, the diameter of the recess in the intermediate layer, starting from the opening in the polishing agent carrier, increases toward the main body (preferably continuously), for example, by delimiting the recess by a conical inner peripheral surface of the intermediate layer. This causes - similar to the starting from the body to the polish carrier toward increasing radial outer dimensions of the radially outer region of the intermediate layer - a close to the opening in the polish carrier in the direction of the opening decreasing elastic support of the polish carrier through the radially inner region of the intermediate layer, even at higher polishing pressures Danger to meet that the opening edge of the polish carrier is reflected on the machined surface.

In the polishing plate, the circumferential contour formed by the radially outer region of the intermediate layer may in principle have any desired geometry, as long as the radial outer dimensions of the radially outer region of the intermediate layer from the base body in the direction of the polishing medium carrier increase (preferably continuously), for example, the radially outer region of Intermediate layer have a toroidal outer peripheral surface. However, in view of a simple production of the polishing plate is preferred, an embodiment in which the radially outer region of the intermediate layer has a substantially frusto-conical outer peripheral surface.

In principle, it is possible for the main body to have an end face facing the intermediate layer, which is preformed toroidally in accordance with the macrogeometry of the surface to be machined, such as in FIG DE-A-10 2005 010 583 described. Investigations by the applicant have shown, however, that it is sufficient for the majority of processing cases when the base body has an intermediate layer facing, substantially spherical end face to which the intermediate layer is glued. On the one hand, this simplifies the polishing plate production and, on the other hand, reduces the number of polishing plates to be provided in the production of prescriptions for the fine processing of the spectacle lenses.

Furthermore, the recess in the intermediate layer can extend as far as the main body. Such a continuous recess is not only particularly easy to produce, but also advantageously maximizes the uptake volume of the reservoir formed by the recess for the liquid polishing agent. An even further enlargement of the polishing agent reservoir is possible by also adjoining the recess in the intermediate layer, a recess in the body.

Investigations by the Applicant have shown that the maximum radial width of the radially outer region of the intermediate layer in the undeformed state of the polishing plate should be between 3 and 10% of the maximum total width of the intermediate layer in order to support the polishing agent carrier substantially constantly elastically on a surface as large as possible without that there is a risk of pictures of the polishing plate edge on the machined surface.

The polishing plate according to the invention can advantageously be used on a tool for fine machining of optically effective surfaces on, in particular, spectacle lenses, comprising a base body which can be attached to a tool spindle of a processing machine, a joint part which has a tilting and longitudinally movably guided receiving piece with respect to the base body, to which a bellows connects in the direction of the main body, by means of which the joint part is fixed to the main body and a limited by the main body and the joint part pressure medium chamber which is optionally acted upon with a (liquid or gaseous) pressure medium, wherein the polishing plate interchangeable the receiving piece of the joint part is held.

In order to ensure the simplest possible interchangeability of the polishing plate, it is preferred if the polishing plate is held by means of a snap connection on the receiving piece of the joint part.

1. (a) Ausbilden des Grundkörpers - z.B. spanend oder in hier bevorzugter, besonders kostengünstiger Weise spritzgießtechnisch, insbesondere aus Kunststoff;
2. (b) Bereitstellen eines flächigen Rohmaterials für die Zwischenschicht, das eine im wesentlichen konstante Dicke aufweist - ein solches Rohmaterial, etwa Schaumstoffplatten, ist am Markt ohne weiteres und kostengünstig erhältlich;
3. (c) Spannen des Rohmaterials für die Zwischenschicht über eine konvex gekrümmte Fläche eines Gegenstempels und Ausstanzen der Zwischenschicht vermittels eines eine Ringschneide aufweisenden Stanzwerkzeugs - hierbei wird auf besonders einfache Weise, da quasi "automatisch" eine Außenumfangsfläche an der Zwischenschicht, d.h. dem ausgestanzten Rohmaterialabschnitt erzeugt, die schon im unverformten, ebenen Zustand des Rohmaterialabschnitts im wesentlichen eine Kegelstumpfform aufweist;
4. (d) ggf. Zuschneiden des Poliermittelträgers entsprechend der größeren Stirnfläche der unverformten Zwischenschicht, d.h. des unverformten, ebenen Rohmaterialabschnitts - ein solches separates Zuschneiden kann entfallen, wenn der Poliermittelträger bereits einstückig mit der Zwischenschicht ausgebildet ist, z.B. durch die sogenannte "Gießhaut" (Trennschicht zur Gießform) an einem Schaumstoffstück, die herstellungstechnologiebedingt ist und bei handelsüblichen Schaumstoffplatten in der Regel weggeschnitten wurde; und
5. (e) Verkleben des Grundkörpers, der Zwischenschicht und - falls separat vorhanden - des Poliermittelträgers zur Ausbildung des vorbeschriebenen, sandwichartigen Verbunds.

A particularly simple method for producing the polishing plate according to the invention provides the following steps in the further course of the invention:

1. (A) forming the base body - for example by machining or in this case more preferably, particularly cost-effective injection molding, in particular plastic;
2. (b) providing a sheetstock for the intermediate layer which has a substantially constant thickness - such raw material, such as foam sheets, is readily available on the market at low cost;
3. (c) Clamping of the raw material for the intermediate layer via a convexly curved surface of a counter punch and punching of the intermediate layer by means of a punch having a ring cutting - this is in a particularly simple manner, as quasi "automatically" creates an outer peripheral surface of the intermediate layer, ie the punched raw material section which already has a substantially truncated cone shape in the undeformed, flat state of the raw material section;
4. (D) optionally cutting the polish carrier corresponding to the larger face of the undeformed intermediate layer, ie the undeformed, flat raw material section - such a separate cutting can be omitted if the polish carrier is already formed integrally with the intermediate layer, eg by the so-called "casting skin" (separating layer to the mold) on a piece of foam, which is manufacturing technology-related and has been cut away in commercial foam boards usually; and
5. (e) bonding the base body, the intermediate layer and, if present separately, the polishing medium carrier to form the above-described sandwich-type composite.

Furthermore, the cutting of the polish carrier can be done by means of the punch and the counter punch for punching the intermediate layer, so that this no separate tool must be used and the cutting can be done quickly. Finally, the punching of the intermediate layer and the cutting of the polish carrier can also take place in a joint step, even if these are separate raw materials. This too is conducive to a fast, dimensionally stable production of the polishing plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine abgebrochene Längsschnittansicht eines Werkzeugs zur Feinbearbeitung von optisch wirksamen Flächen an Brillengläsern, an dem ein nicht-erfindungsgemäßer Polierteller lösbar gehalten ist, der sich mit einer zu bearbeitenden Fläche in Bearbeitungseingriff befindet, in einem gegenüber der Realität etwas vergrößerten Maßstab;

Fig. 2

eine perspektivische Ansicht des Werkzeugs gemäß Fig. 1 von schräg vorne/oben, wobei der Polierteller von dem Werkzeug abgenommen wurde, um werkzeugseitig die Schnittstelle zwischen Werkzeug und Polierteller zu zeigen;

Fig. 3

eine perspektivische Ansicht des vom Werkzeug abgenommenen Poliertellers gemäß Fig. 1 von schräg links/unten, zur Veranschaulichung der Schnittstelle zwischen Werkzeug und Polierteller auf der Poliertellerseite;

Fig. 4

eine Unteransicht des vom Werkzeug abgenommenen Poliertellers gemäß Fig. 3 von unten in Fig. 1;

Fig. 5

eine Schnittansicht des Poliertellers gemäß Fig. 3 entsprechend der Schnittverlaufslinie V-V in Fig. 4;

Fig. 6

eine Schnittansicht des Poliertellers gemäß Fig. 3 entsprechend der Schnittverlaufslinie VI-VI in Fig. 4;

Fig. 7

eine schematische Längsschnittansicht einer Vorrichtung zum Ausstanzen der Zwischenschicht für den Polierteller , mittels der am radial äußeren Bereich der Zwischenschicht eine im wesentlichen kegelstumpfförmige Außenumfangsfläche ausbildbar ist;

Fig. 8

eine schematische Längsschnittansicht einer vermittels der Vorrichtung gemäß Fig. 7 ausgestanzten Zwischenschicht, bevor diese zur Ausbildung des Poliertellers mit dem Grundkörper und dem Poliermittelträger verklebt wird; und

Fig. 9

eine hinsichtlich des Schnittverlaufs der Fig. 5 entsprechende Schnittansicht eines Poliertellers gemäß der Erfindung in einem gegenüber Fig. 5 nochmals vergrößerten Maßstab, mit einer zentralen Öffnung im Poliermittelträger;

In the following the invention with reference to preferred embodiments with reference to the accompanying, partially schematic drawings is explained in more detail, in which like reference characters designate the same or corresponding parts. In the drawings show:

Fig. 1

a broken longitudinal sectional view of a tool for fine machining of optically effective surfaces of spectacle lenses, on which a non-inventive polishing plate is releasably held, which is in machining engagement with a surface to be machined, in a relation to reality slightly enlarged scale;

Fig. 2

a perspective view of the tool according to Fig. 1 obliquely from the front / top, wherein the polishing plate was removed from the tool to the tool side to show the interface between the tool and polishing plate;

Fig. 3

a perspective view of the tool removed from the polishing pad according to Fig. 1 from obliquely left / bottom, to illustrate the interface between tool and polishing plate on the polishing pad side;

Fig. 4

a bottom view of the removed from the tool polishing plate according to Fig. 3 from the bottom in Fig. 1 ;

Fig. 5

a sectional view of the polishing pad according to Fig. 3 according to the section line VV in Fig. 4 ;

Fig. 6

a sectional view of the polishing pad according to Fig. 3 according to the section line VI-VI in Fig. 4 ;

Fig. 7

a schematic longitudinal sectional view of an apparatus for punching the intermediate layer for the polishing plate, by means of the radially outer region of the intermediate layer, a substantially frusto-conical outer peripheral surface is formed;

Fig. 8

a schematic longitudinal sectional view of a means of the device according to Fig. 7 punched intermediate layer before it is glued to the formation of the polishing plate with the main body and the polishing agent carrier; and

Fig. 9

with respect to the cutting of the Fig. 5 corresponding sectional view of a polishing plate according to the invention in a opposite Fig. 5 again enlarged scale, with a central opening in the polish carrier;

DETAILED DESCRIPTION OF THE EMBODIMENTS

According to the Fig. 1 . 5 . 6 and 9 has a polishing plate 10 for a tool 12 for fine machining of optically active surfaces F to particular lenses L a central axis M having base body 14 to which a softer relative to the base body 14 intermediate layer 16 is fixed, which rests a polishing agent carrier 18. It is essential, inter alia, that the intermediate layer 16 with respect to the central axis M has a radially inner region 20 of substantially constant axial thickness D and an adjoining, radially outer region 22, which, as will be described in more detail below, to special A manner is formed to prevent the edge of the polishing pad 10 on the machined surface F of the lens L in the form of very fine, scratch-like microstructures. In the Fig. 1 . 5 . 6 and 9 dashed lines indicate the boundary between the radially inner region 20 and the radially outer region 22 of the intermediate layer 16.

As the Fig. 1 and 2 show, the tool 12 has a base body 24, which at an in Fig. 1 indicated by dashed lines tool spindle 26 of a processing machine (not shown) is attachable. Further, the tool 12 has a generally numbered with 28 joint part having a respect to the base body 24 by means of a ball joint 30 and a guide member 32 tilt and longitudinally movably guided receiving piece 34 on which the polishing plate 10 is held interchangeable in a manner to be described. At the receiving piece 34 is followed in the direction of the base body 24 to a bellows 36, by means of which the hinge part 28 is rotatably mounted on the base body 24. The main body 24 and the joint part 28 delimit a pressure medium chamber 38, which can be acted upon via a channel 40 in the guide member 32 selectively with a suitable liquid or gaseous pressure medium (eg oil or compressed air) to during the processing of the optically active surface F on the lens L. Apply a processing pressure on the receiving piece 34 and the polishing plate 10 resting thereon. Further details on the structure of the tool 12 are the publications DE-A-10 2005 010 583 A1 and EP-A-1 473 116 the applicant, to which reference is expressly made in this regard to avoid repetition at this point.

In that regard, it can be seen that the receiving piece 34 of the joint part 28 is supported by means of the guide member 32 in the transverse direction relative to the base body 24 of the tool 12. At the same time, the guide member 32 follow the receiving piece 34 in the axial direction and vice versa, when the pressure medium chamber 38 is acted upon via the channel 40 with the pressure medium or the receiving piece 34 by external action (from above in Fig. 1 ) is pressed in the direction of the base body 24. In addition, the receiving piece 34 of the joint part 28 can tilt due to the ball joint 30 to the guide member 32 on the guide member 32, wherein the bellows 36 of the joint part 28 is deformed accordingly.

In order to ensure a secure hold of the polishing pad 10 and a rotational drive of the polishing pad 10 with the receiving piece 34 of the tool 12, are on the facing surfaces of the receiving piece 34 of the joint part 28 and the base 14 of the polishing pad 10, ie at an in Fig. 1 formed on the upper end face 42 of the receiving piece 34 and the bottom 44 of the base body 14 complementary shaped structures which interlock in particular form-fitting manner. These structures are best in the Fig. 2 (Tool 12) and 3 (polishing plate 10) to recognize.

Accordingly, which is preferably injection molded from a plastic material holding section 34 of the hinge portion 28 provided on its end surface 42 with a central rotary driving projection 46 seen in a plan view essentially the form of a sechszahnigen star comprises (Torx ^® -like outer profile). On opposite sides of the rotary driving projection 46, a substantially mushroom-shaped retaining projection 48 is provided on the end face 42 of the receiving piece 34, which forms an undercut 50. Further, the receiving piece 34 is provided at its end face 42 with a total of four substantially cylindrical Orientiervorsprüngen 52 which are arranged in pairs on opposite sides of the rotary driving projection 46 and 90 ° with respect to the retaining projections 48 angularly offset about the central axis M.

Which is also preferably made of a plastic such as an ABS (A crylnitril- B utadien- S styrene-polymer), about Terluran® GP 35 from BASF, injection molded base body 14 of the polishing plate 10, however, is formed honeycomb-like on its underside 44 with a centrally disposed counter-profile 54 for the rotary driving projection 46 on the tool 12, of which star-shaped reinforcing ribs 56 extend to the outer edge of the base body 14, and arranged on opposite sides of the counter profile 54 between the reinforcing ribs 56, substantially hollow cylindrical holding portions 58 which cooperate with the retaining projections 48 on the tool 12 to the polishing plate 10 in the manner of a snap connection on Holding piece 34 of the joint part 28. For this purpose, the holding portions 58 are seen in a plan view ( Fig. 4 ) is slotted cross-shaped for the formation of four spring arms 60, each spring arm 60 carries at its free end with respect to an axis of symmetry of the respective holding portion 58 radially inwardly directed detent 62 (in Fig. 3 indicated), which is dimensioned and arranged so that it is able to lock with the undercut 50 on each associated retaining projection 48 of the tool 12.

In that regard, it will be apparent to those skilled in the art that by form-locking engagement of Drehitnahmervorsprung 46 and counter profile 54 is provided for a substantially backlash movement, in particular rotational drive of the polishing pad 10 with the tool 12, while functionally separated, the retaining projections 48 cooperate with the holding portions 58, to hold the polishing plate 10 by locking in the axial direction of the tool 12. Here, the Orientiervorsprünge 52 in cooperation with the reinforcing webs 56 ensure that the polishing plate 10 can not be placed so angularly offset on the tool 12 that the polishing plate 10 with its underside 44 surface on the end face 42 of the tool 12 comes to rest, without a latching between the holding projections 48 and the holding portions 58 takes place. With the correct angle relative position of the polishing pad 10 and the tool 12, in the state of the polishing plate 10 mounted on the tool 12, a reinforcing web 56 extends between a pair of orientation projections 52, namely those reinforcing webs 56 that are in relation to the holding sections 58 of FIG Base body 14 are arranged angularly offset by 90 ° about the central axis M.

Like that Fig. 1 and 3 to 6 it can be seen, closes on the outer peripheral side of the underside 44 of the base body 14 via the otherwise cylindrical outer peripheral surface 64 of the base body 14 radially outwardly projecting annular collar 66, which according to the Fig. 1 . 5 and 6 has a hook-shaped cross-section. The annular collar 66 serves as a handle for a gripper (not shown) of an automatic polishing plate changing device (also not shown).

The in the Fig. 1 and 5 upper, adjacent to the intermediate layer 16 end face 68 of the base body 14 is preformed substantially spherical in the illustrated embodiments and bulges virtually the intermediate layer 16 against. However, the end face 68 may also be shaped differently, eg toroidally, in accordance with the macrogeometry of the surface F to be machined.

To mention the design of the main body 14 is finally still that the annular collar 66 according to the 3 and 4 Outside circumference with two seen in a plan view semicircular recesses 70 is provided. These serve to mark the polishing plate 10, in such a way that the in Fig. 4 with 72 numbered angular distance of the recesses 70 encoded about the central axis M represents a measure of the curvature (in diopters) of the end face 68.

At the end face 68 of the main body 14, the intermediate layer 16 is firmly fixed, for example by means of a suitable adhesive. The material of the intermediate layer 16 may be, for example, an open-celled PU (polyurethane) foam, as it is available, for example, under the trade name Sylomer® R from Getzner Werkstoffe GmbH, Berlin, Germany.

This has a hardness of about 60 to Shore A. The polisher carrier 18 facing top of the intermediate layer 16 may, but need not be provided with a final, manufacturing technology-related "casting" (release layer to the mold, not shown), the intermediate layer 16 an additional Stiffness gives; if necessary, such a "casting skin" can even form the polish carrier itself. The thickness D of the intermediate layer 16 in its radially inner region 20 may correspond to the respective processing requirements, for example between 2 and 10 mm. As already mentioned, this thickness D in the radially inner region 20 of the intermediate layer 16 is substantially constant, so that the elastic support of the polishing medium carrier 18 by means of the intermediate layer 16 in this region 20 is also substantially constant.

In the illustrated embodiment, the radial outer dimensions r of the radially outer region 22 of the intermediate layer 16, starting from the base 14 towards the polish carrier 18 towards continuously increase - namely, such that the radially outer portion 22 of the intermediate layer 16 has a substantially frusto-conical outer peripheral surface 74, the inclination with respect the central axis M is greater than the inclination of any surface normal on the end face 68 of the base body 14 with respect to the central axis M - so that the elastic support of the polishing medium carrier 18 by means of the intermediate layer 16 in the radially outer region 22 to the outer edge 76 of the polishing medium carrier 18 decreases continuously , This causes - as already mentioned - causes the polishing pressure and thus the polishing removal in the edge region of the polishing pad 10 decreases and at the same time the outer edge 76 of the polish carrier 18 - compared to a free, unsupported outer edge of the polish carrier, as he from DE-A-10 2005 010 583 is known - is attenuated in its axial movements. As a result, it prevents the Outer edge 76, in particular those formed by this, in the Fig. 1 and 5 The upper edge of the polishing agent carrier 18 undesirably "presses" or depicts on the machined surface F of the spectacle lens L.

To mention in this context is still (cf. Fig. 5 ), that the maximum radial width b of the radially outer portion 22 of the intermediate layer 16 in the undeformed state of the polishing plate 10, that is, when it is not pressed against the surface to be processed F of the lens L, approximately between 3 and 10% of the maximum total width B of Intermediate layer 16 is. Finally, it should also be pointed out that the transition between the outer peripheral surface 64 of the base body 14 and the outer peripheral surface 74 of the intermediate layer 16 does not necessarily have to be infinitely variable. In particular, the base body over the intermediate layer can protrude radially outward, such as in the DE-A-10 2005 010 583 disclosed.

In the polish carrier 18, also called "polishing film" or "polishing pad", according to Fig. 1 forming the active machining tool component is a commercially available, flexible and abrasion-resistant fine grinding or polishing agent carrier, such as a polyurethane (P oly ur ethane) film having a thickness of 0.5 to 1.4 mm and a Hardness between 12 and 45 after Shore D. In this case, the polishing agent carrier 18 is rather thicker if, by means of the polishing plate 10, a pre-polishing is to take place, but rather thinner in the case of a fine polishing.

As already apparent from the preceding explanations, the radial dimensions of the polishing medium carrier 18 are selected so that in a plan view from above in the Fig. 1 and 5 seen in this embodiment, circular polish carrier 18 ends with its outer edge 76 on the outer peripheral surface 74 of the underlying intermediate layer 16.

Finally, the polishing agent carrier 18 is secured in the illustrated embodiment by means of a suitable adhesive to the intermediate layer 16. However, the polish carrier 18 may be otherwise more or less permanently bonded to the intermediate layer 16, e.g. by vulcanization or Aufkletten. In any case, the connection between the polish carrier 18 and the intermediate layer 16 must be so strong that a movement entrainment, in particular rotational drive of the polish carrier 18 is ensured with the intermediate layer 16 at any time during processing.

In the fine machining of the optically active surface F of the lens L to be processed, which takes place in a known manner by means of unbound grain, which is supplied by a suitable liquid to the point of contact between polishing plate 10 and lens L - mainly from radially outside by means of flexibly adjustable hoses (not shown) - are the tool 12 and the lens L in a conventional manner substantially synchronously, ie driven in the same direction and at substantially the same speed. Here, the tool 12 and the lens L are simultaneously pivoted relative to each other, so that the engagement area between the polishing plate 10 and lens L changes continuously. These fine machining processes, in which, for example, in the case of machining of free-form surfaces, the pivotal movement takes place in a fixed setting about the center of a "best fit radius", ie an approximated center point of the surface F of the spectacle lens L to be machined, or the relative movement between the tool 12 and spectacle lens L. is generated by a path-controlled method in two CNC linear axes and possibly a CNC pivot axis are well known to those skilled in the art and are therefore not described in detail here.

1. (a) Ausbilden des Grundkörpers 14, insbesondere durch Spritzgießen aus Kunststoff, wobei die vollständige Geometrie des Grundkörpers 14 mit Gegenprofil 54, Verstärkungsstegen 56 und Halteabschnitten 58 (unter Zwangsentformung der Rastnasen 62) an der Unterseite 44, dem Ringbund 66 am Außenumfang und der im wesentlichen sphärischen Stirnfläche 68 zugleich und ohne die Notwendigkeit einer Nachbearbeitung, d.h. "werkzeugfallend" ausgebildet wird.
2. (b) Bereitstellen eines - im Handel problemlos erhältlichen - flächigen Rohmaterials für die Zwischenschicht 16, das eine im wesentlichen konstante Dicke D aufweist.
3. (c) Spannen des Rohmaterials für die Zwischenschicht 16 über eine konvex gekrümmte Fläche 78 eines Gegenstempels 80 einer in Fig. 7 schematisch dargestellten Stanzvorrichtung 82 und Ausstanzen der Zwischenschicht 16 - ggf. unter Niederhalten derselben auf der Gegenstempelfläche 78 - vermittels eines eine Ringschneide 84 aufweisenden Stanzwerkzeugs 86 der Stanzvorrichtung 82. Hieraus ergibt sich die in Fig. 8 gezeigte, zugeschnittene Zwischenschicht 16, die im unverformten, planebenen Zustand eine erste Stirnfläche 88, eine zweite Stirnfläche 90 und eine Außenumfangsfläche 74 aufweist, wobei letztere infolge der vorbeschriebenen Stanztechnik bereits im wesentlichen eine Kegelstumpfform besitzt.
4. (d) Zuschneiden des Poliermittelträgers 18 entsprechend der größeren (zweiten) Stirnfläche 90 der unverformten Zwischenschicht 16 (siehe Fig. 8). Dies kann bevorzugt mittels des Stanzwerkzeugs 86 und des Gegenstempels 80 zum Ausstanzen der Zwischenschicht 16 erfolgen, ggf. sogar in einem gemeinsamen, d.h. im zuletzt beschriebenen Arbeitsschritt.
5. (e) Verkleben des Grundkörpers 14, der Zwischenschicht 16 und des Poliermittelträgers 18 zu dem in den Fig. 1, 5 und 6 dargestellten sandwichartigen Verbund, wobei der Poliermittelträger 18 auf die zweite Stirnfläche 90 der Zwischenschicht 16 und die Zwischenschicht 16 mit ihrer ersten Stirnfläche 88 auf den Grundkörper 14 aufgeklebt wird. Hierbei "spreizt" die Zwischenschicht 16 infolge der Vorwölbung der Stirnfläche 68 des Grundkörpers 14 noch weiter auf, d.h. die Neigung der im wesentlichen kegelstumpfförmigen Außenumfangsfläche 74 der Zwischenschicht 16 bezüglich der Mittelachse M nimmt am fertigen Polierteller 10 (Fig. 1 und 3 bis 6) verglichen mit der Zwischenschicht 16 im unverformten Zustand (Fig. 8) noch zu.

A particularly simple method for producing the above-described polishing plate 10 comprises the following steps, wherein also on the FIGS. 7 and 8 to refer is:

1. (A) forming the base body 14, in particular by injection molding of plastic, wherein the complete geometry of the base body 14 with mating profile 54, reinforcing ribs 56 and holding portions 58 (under forced removal of the locking lugs 62) on the bottom 44, the annular collar 66 on the outer circumference and the essential spherical face 68 at the same time and without the need for post-processing, ie "tool falling" is formed.
2. (b) providing a flat raw material for the intermediate layer 16, which has a substantially constant thickness D, which is readily available commercially.
3. (c) clamping the raw material for the intermediate layer 16 over a convexly curved surface 78 of a counter punch 80 of an in Fig. 7 schematically illustrated punching device 82 and punching the intermediate layer 16 - possibly while holding down the same on the counter punch surface 78 - by means of a ring cutting 84 having punching tool 86 of the punching device 82. This results in the Fig. 8 shown, cut intermediate layer 16 which has a first end face 88, a second end face 90 and an outer peripheral surface 74 in the undeformed, planar state, the latter already having a substantially truncated cone shape due to the above-described punching technique.
4. (D) cutting the polishing medium carrier 18 corresponding to the larger (second) end face 90 of the undeformed intermediate layer 16 (see Fig. 8 ). This can preferably by means of the punching tool 86 and the counter punch 80 for punching the Intermediate layer 16, possibly even in a common, ie in the last-described step.
5. (E) bonding the base body 14, the intermediate layer 16 and the polishing medium carrier 18 to the in the Fig. 1 . 5 and 6 shown sandwich-like composite, wherein the polishing agent carrier 18 is adhered to the second end face 90 of the intermediate layer 16 and the intermediate layer 16 with its first end face 88 on the base body 14. In this case, the intermediate layer 16 "spreads" due to the protrusion of the end face 68 of the main body 14 even further, ie the inclination of the substantially frusto-conical outer peripheral surface 74 of the intermediate layer 16 with respect to the central axis M takes on the finished polishing plate 10 (FIG. Fig. 1 and 3 to 6 ) compared to the intermediate layer 16 in the undeformed state ( Fig. 8 ) still too.

It should be mentioned at this point that even though the bonding of an intermediate layer, which has a cylindrical outer peripheral surface in the undeformed, flat state, would lead to a bulging end face of the base body to a "spreading" of the intermediate layer, so that the outer peripheral surface of the intermediate layer then would essentially have a (light) truncated cone shape. This would - unlike the above-described structure of the polishing plate - but do not cause the effect caused by the intermediate layer, elastic support of the polish carrier, which is normal to see the end face of the body decreases towards the outer edge of the polish medium carrier.

Fig. 9 is to be described below to avoid repetition only insofar as they differ from those described above Fig. 1 to 8 different.

In the embodiment according to Fig. 9 the polishing medium carrier 18 is additionally provided in a central region with (at least) one through opening 92, which in the case shown has a circular shape and can be formed, for example, by cutting or punching. Preferably, the opening 92 in the polishing medium carrier 18 occupies a surface area of 0.25 to 2% of the total area of the polishing medium carrier 18 facing the surface F of the lens L to be processed. The opening 92 provides pressure equalization during processing and provides liquid polishing agent from within the intermediate layer 16, thereby providing better rinsing and cooling of otherwise deprived areas of the polishing platen 10. Such a "central" supply of polishing agent is particularly advantageous when the polishing plate 10 rotates at a relatively high speed and thus the acting centrifugal forces are anxious to "drive" the polishing agent radially outward.

In the in Fig. 9 illustrated embodiment joins the opening 92 in the polishing medium carrier 18 in the direction of the base body 14 a recess 94 in the intermediate layer 16, which extends to the base body 14 back. Also in the base body 14 is followed by the recess 94 in the intermediate layer 16 steplessly a recess 96 at. The recesses 94 and 96 in the intermediate layer 16 and in the main body 14 serve during processing as (extended) reservoir for the liquid polishing agent.

While the recess 96 in the base body 14 is cylindrical, the diameter d of the recess 94 in the intermediate layer 16, starting from the opening 92 in the polish carrier 18 to the main body 14 toward continuously increases. Such a shape of the recess 94 can be made analogous to the substantially frusto-conical outer peripheral surface 74 of the intermediate layer 16 by punching, wherein a suitable Naturally, a punching device would have a smaller-diameter annular cutting edge on the punching tool and expediently a greater curvature on the counter-punching surface than in FIG Fig. 7 shown.

The thus substantially frustoconical, the recess 94 in the intermediate layer 16 outwardly bounding inner peripheral surface of the intermediate layer 16 has basically the same effect as the substantially frusto-conical outer peripheral surface of the intermediate layer 16, namely, it causes the elastic support of the polishing medium carrier 18 through the radially inner region 20 of the intermediate layer 16 near the opening 92 in the polishing medium carrier 18 decreases in the direction of the opening 92 to ensure that even at higher polishing pressures that the edge of the opening 92 in the polishing medium carrier 18 does not image on the machined surface F.

LIST OF REFERENCE NUMBERS

10

polishing plate

12

Tool

14

body

16

interlayer

18

Polisher carrier

20

radially inner region of the intermediate layer

22

radially outer region of the intermediate layer

24

body

26

tool spindle

28

joint part

30

Ball head connection

32

guide member

34

spigot

36

bellow

38

Fluid chamber

40

channel

42

face

44

bottom

46

Rotary driving projection

48

retaining projection

50

undercut

52

Orientiervorsprung

54

counter profile

56

strengthening web

58

holding section

60

spring arm

62

locking lug

64

Outer circumferential surface

66

collar

68

face

70

recess

72

angular distance

74

Outer circumferential surface

76

outer edge

78

Gegenstempel area

80

counterpunch

82

punching device

84

serrated

86

punching tool

88

first end face

90

second end face

92

opening

94

recess

96

recess

b

radial width of the radially outer region of the intermediate layer

d

Diameter of the recess in the intermediate layer

r

Radial outer dimensions of the radially outer region of the intermediate layer

B

Total width of the intermediate layer

D

axial thickness of the intermediate layer

F

optically effective surface

L

lens

M

central axis

Claims (12)

1. Polishing disc (10) for a tool (12) for the fine machining of optically active surfaces (F) particularly on spectacle lenses (L), comprising a main body (14) which has a center axis (M) and on which there is fixed an intermediate layer (16) which is softer than the main body (14) and on which a polishing agent carrier (18) rests, wherein the intermediate layer (16) has, with respect to the center axis (M), a radial inner region (20) of substantially constant axial thickness (D) and an adjoining radial outer region (22) having radial outer dimensions (r) which increase from the main body (14) towards the polishing agent carrier (18), so that the elastic support of the polishing agent carrier (18) by the intermediate layer (16) in the radial outer region (22) thereof decreases towards the outer edge (76) of the polishing agent carrier (18), and wherein the polishing agent carrier (18) is provided with at least one opening (92) in a central region and the at least one opening (92) in the polishing agent carrier (18) is adjoined in the direction of the main body (14) by a cutout (94) in the intermediate layer (16), characterized in that the diameter (d) of the cutout (94) in the intermediate layer (16) increases from the opening (92) in the polishing agent carrier (18) towards the main body (14).
2. Polishing disc (10) according to claim 1, characterized in that the radial outer region (22) of the intermediate layer (16) has a substantially frustoconical outer peripheral surface (74).
3. Polishing disc (10) according claim 1 or 2, characterized in that the main body (14) has a substantially spherical end face (68) facing towards the intermediate layer (16), to which end face the intermediate layer (16) is securely adhesively bonded.
4. Polishing disc (10) according to any one of the preceding claims, characterized in that the cutout (94) in the intermediate layer (16) extends as far as the main body (14).
5. Polishing disc (10) according to claim 4, characterized in that the cutout (94) in the intermediate layer (16) is adjoined by a cutout (96) in the main body (14).
6. Polishing disc (10) according to any one of the preceding claims, characterized in that the maximum radial width (b) of the radial outer region (22) of the intermediate layer (16) in the non-deformed state of the polishing disc (10) is between 3 and 10% of the maximum total width (B) of the intermediate layer (16).
7. Tool (12) for the fine machining of optically active surfaces (F) particularly on spectacle lenses (L), comprising
   a main body (24) which can be attached to a tool spindle (26) of a machining machine,
   an articulated part (28) which has a holding section (34) guided such that it can be tilted and moved longitudinally with respect to the main body (24), which holding section is adjoined in the direction of the main body (24) by a bellows section (36), by means of which the articulated part (28) is fixed to the main body (24) such that it can rotate therewith,
   a pressure medium chamber (38) which is delimited by the main body (24) and the articulated part (28) and which can selectively be acted upon by a pressure medium, and
   a polishing disc (10) according to any one of the preceding claims, which is held on the holding section (34) of the articulated part (28) in an exchangeable manner.
8. Tool (12) according to claim 7, characterized in that the polishing disc (10) is held on the holding section (34) of the articulated part (28) by means of a snap-in connection (48, 58).
9. Method for producing a polishing disc (10) according to claim 1, comprising the following steps:

   forming the main body (14),

   providing a flat raw material for the intermediate layer (16), which has a substantially constant thickness (D),

   pulling taut the raw material for the intermediate layer (16) over a convexly curved surface (78) of a counter-punch (80) and punching out the intermediate layer (16) by means of a punching tool (86) having an annular cutter (84),

   optionally cutting the polishing agent carrier (18) to match the larger end face (90) of the non-deformed intermediate layer (16), and

   adhesively bonding the main body (14), the intermediate layer (16) and optionally the polishing agent carrier (18) to form a sandwich-like assembly.
10. Method according to claim 9, characterized in that the main body (14) is injection-molded from a plastic.
11. Method according to claim 9 or 10, characterized in that the cutting of the polishing agent carrier (18) takes place by means of the punching tool (86) and the counter-punch (80) for punching out the intermediate layer (16).
12. Method according to claim 11, characterized in that the punching-out of the intermediate layer (16) and the cutting of the polishing agent carrier (18) take place in a common operating step.

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