EP1593458B1 - Blockpiece for holding an optical workpiece, especially an eyeglass lens, for its treatment - Google Patents

Abstract

The block for holding an optical workpiece, in particular, a spectacle lens (L) during its machining comprises an injection molded main body (42) whose face (44) has at least two cutouts (52) for a temporarily deformable material (46).

Description

TECHNICAL AREA

The present invention relates to a block piece for holding an optical workpiece for its processing according to the preamble of claim 1. Such a block piece is known from the German standard DIN 58766. In particular, the invention relates to a block piece for holding a spectacle lens for processing thereof, as masses of prescription workshops, i. Production plants for the production of individual eyeglass lenses from the usual materials (polycarbonate, mineral glass, CR 39, HI index, etc.) are used according to the recipe.

STATE OF THE ART

In recipe workshops, the following process steps are usually run through: First, a suitable right and / or left eyeglass lens blank is removed from a semi-finished stock. Semifinished product insofar as seen in a plan view usually round or oval, not yet gerilierten eyeglass lens blanks are already finished on one of their two optically active surfaces. Then the eyeglass lens blanks are prepared for the blocking process, namely by applying a suitable protective film or a suitable protective lacquer to protect the already finished optically effective surface. Next, the so-called "blocking" of the spectacle lens blanks takes place. Here, the eyeglass lens blank is connected to a suitable block piece, for example a block piece according to the German standard DIN 58766. For this purpose, the block piece is first brought into a predetermined position relative to the protected, already finished surface of the spectacle lens blank and then in this position the space between block piece and eyeglass lens blank is filled with a molten material (wood-metal or wax). After solidification of the filling material, the block piece is a receptacle for processing the eyeglass lens blank. Only then can the eyeglass lens blanks be pre-machined by grinding, milling or turning, the previously unprocessed optically effective surface of the respective eyeglass lens blank receiving its macrogeometry according to the recipe. Then, the fine machining of the spectacle lenses takes place, in which the preprocessed optically effective surface of the respective spectacle lens receives the desired microgeometry. Depending on, inter alia, the material of the spectacle lenses, the fine machining is subdivided into a fine grinding process and an adjoining polishing process, or, if a polishable surface has already been produced during pre-processing, merely a polishing process. Only after the polishing process, the spectacle lens is separated from the block piece before finally cleaning steps and possibly further finishing steps, such as an antireflection or hard coating of the spectacle lenses followed. The block piece thus remains at several processing operations on the spectacle lens and this must keep it reliable.

The Fig. 11 to 14 show a previously known block piece 10, which is designed according to the German standard DIN 58766. The block piece 10 has an annular base body 12 which is machined from steel or an aluminum alloy. Starting from a flat, annular end face 14 on which the spectacle lens (not shown) can be blocked by means of the temporarily deformable material (not shown), the base body 12 has a cylindrical clamping surface 16 on the outer peripheral side, via which the spectacle lens blocked on the base body 12 abuts a spindle (not shown) of a processing machine can be fixed. At the clamping surface 16 is followed by a conical centering surface 18, which extends to a flat annular surface 20 tapers at the bottom of the body 12 back.

The main body 12 further has a central through-bore 22, which can be divided into three longitudinal sections. Starting from the end face 14, the through-bore 22 initially has a first conical surface 24, which tapers in the direction of the lower annular surface 20. Connected to the first conical surface 24 is a second conical surface 26, which widens in the direction of the lower annular surface 20, so that the second conical surface 26, viewed from the end surface 14, forms an annular undercut on the main body 12. The second conical surface 26 finally merges via a planar annular shoulder 28 into a third conical surface 30, which is significantly longer than the first and second conical surfaces 24, 26 and likewise widens toward the lower annular surface 20.

Starting from the lower annular surface 20 of the base body 12 is further provided with two with respect to the central axis M diametrically opposite recesses 32 which extend in the longitudinal direction of the base body 12 substantially over the entire length of the centering surface 18, in a side view Fig. 12 seen are substantially V-shaped and serve a centering of the block piece 10 with respect to the central axis of the spindle (not shown) of the processing machine. Furthermore, starting from the lower annular surface 20 with respect to the recesses 32 angularly offset further recess 34 is introduced with parallel side walls in the base body 12, which serves an angular orientation of the block piece 10, ie ensures that the block piece 10 is not rotated by 180 ° on the spindle the machine is clamped. Finally, two parallel to the central axis M blind bores 36 are introduced into the annular shoulder 28 with respect to the central axis M diametrically opposite sides of the base body 12.

In the blocked state of the spectacle lens (not shown) fills the fusible material, the through hole 22 at least in the region of the first and second conical surface 24, 26 and the blind holes 36 in the base body 12. As a result, the spectacle lens is held in a form-fitting manner on the block piece 10, wherein the fusible material engages behind the second cone surface 26 to bind the spectacle lens in the axial direction on the block piece 10 and engages the blind holes 36 to the spectacle lens against rotation relative to the block piece 10 to back up.

A disadvantage of this determination of the spectacle lens on the block piece 10, however, is seen in the fact that it may come to a certain movement between the spectacle lens and the block piece 10 as a result of a low shrinkage of the cooling meltable material after the blocking process, which is detrimental to the processing accuracy. More specifically, the fusible material in the region of the first and second conical surfaces 24, 26 shrinks slightly in the direction of the central axis M of the base body 12, so that a small annular gap between the outer periphery of the fusible material and the first and second conical surface 24, 26 may result. At the same time shrink into the blind holes 36 engaging projections on the fusible material slightly in itself and move with the shrinkage of the fusible material in the region of the first and second conical surface 24, 26 of the through hole 22 also slightly radially inward. As a result, a substantially linear compression of each of the projections of the fusible material engaging in the blind bores 36 may occur with a surface section of the respective blind bore 36 located radially inward with respect to the central axis M of the base body 12. Are these constraining forces in parallel to the central axis M of the body 12 lying, substantially linear contact area between the respective Projection of the fusible material and the radially inner surface portion of the associated blind bore 36 during processing of the blocked spectacle lens outer, superimposed in particular circumferentially and radially inwardly directed forces, it can lead to a plastic deformation of the fusible material at these investment areas, which ultimately the above-mentioned certain movement between the spectacle lens and the block piece 10 leads.

Another block piece is from the US-A-5,669,807 known. This has a base body with the block-shaped workpiece facing end face and an adjoining the latter outer peripheral surface. While the end surface is undercut-free, the outer peripheral surface is provided with a circumferential groove which serves to receive a temporarily deformable material to secure the workpiece to which the temporarily deformable material adheres to the block piece. At the same time, the temporarily deformable material forms a radially outer bearing surface with respect to the groove, on which the composite formed from the block piece, temporarily deformable material and workpiece can be grasped and tensioned on a drive part.

Finally, the reveals WO 03/018253 A a block piece whose base body is formed of a plastic which is permeable in particular to UV light. To secure the workpiece to the block piece, this prior art uses a UV curable adhesive that is cured by passing UV light through the base.

PRESENTATION OF THE INVENTION

The invention is based on the prior art, as represented by the German standard DIN 58766, the task based, a simple trained block piece for holding an optical workpiece, in particular a spectacle lens, to provide for its processing, where the optical workpiece by means of the temporarily deformable material as reliable as possible and for the whereabouts of the optical workpiece on the block piece permanently free of play can be determined.

This object is achieved by the features specified in claim 1. Advantageous or expedient developments of the invention are subject matter of the claims 2 to 13.

In a block piece for holding an optical workpiece, in particular a spectacle lens, for the machining, which comprises a base body having an end face on which the workpiece is aufblockbar by means of a temporarily deformable material, wherein the end face facing the locked workpiece, and an adjoining the outer surface of the end face clamping surface, over which the blocked on the base body workpiece on a spindle of a processing machine can be fixed, according to the invention of injection-molded plastic base body provided at its end face with at least two recesses for receiving the temporarily deformable material to are arranged on both sides of an imaginary plane which contains the central axis of the base body, and whose the central axis of the base body each closest boundary surface forms an undercut.

In other words, the undercut boundary surfaces of the recesses for receiving the temporarily deformable material on opposite sides of the imaginary plane with respect to the central axis of the body radially inward. As a result of this arrangement of the undercut boundary surfaces, in the case of a shrinkage of the temporarily deformable material in the direction of the central axis of the base body between the respective undercut boundary surface and the temporarily deformable material adjacent thereto, in contrast to the above-described prior art, no gap is produced. On the contrary, the temporarily deformable material is drawn in its shrinkage in the direction of the central axis of the body in the sense of a self-reinforcing solution against the undercut boundary surface of each recess for receiving the temporarily deformable material, the undercut boundary surface of the other recess acts as an abutment. In this case, due to the position of the undercut boundary surfaces and their angular position with respect to the end face of the base body, the temporarily deformable material is also drawn against the end face of the body, so that any axial relative movement between the temporarily deformable material and the base body is prevented. At the same time results between the temporarily deformable material and the undercut boundary surfaces of the recesses for receiving the temporarily deformable material and the end face of the body a frictional engagement, which counteracts an undesirable relative rotation of the temporarily deformable material relative to the base body. In addition, already by the fact that at least two recesses provided for receiving the temporarily deformable material, thus no rotationally symmetrical engagement structures are present, even a positive fixing of the temporarily deformable material against rotation relative to the main body, without requiring additional measures, such as the provision of the blind holes 36 would have to be made in the generic art.

Further, since the base body is injection-molded from plastic, the recesses having the undercut boundary surfaces for receiving the temporarily deformable material can be formed in a simple manner with the aid of transverse slides in the injection mold, so that there is no machining of the in contrast to the generic state of the art Basic body needs. In addition, the use of plastic as a material for the base body advantageously allows the use of liquid solvents and cleaning agents for the block piece, which could not be used until now, because they would have attacked the metallic material of the previously known Blockstück basic body. Last but not least, the use of plastic as a material for the base body also has the advantage that the block piece has a low weight, so that in the processing of the blocked optical workpiece compared to the generic state of the art workpiece lower moving masses are given. All in all, a block piece that can be produced at extremely low cost is created, which causes no problems in particular with regard to the tight fit of the temporarily deformable material and thus of the blocked optical workpiece on the block piece.

In a preferred embodiment of the block piece according to the invention, the inner perimeter surface of the respective recess for receiving the temporarily deformable material is substantially flat and extends from the central axis of the main body approximately over the entire width of the end face of the main body. This results in a slot-like shape of the recesses for receiving the temporarily deformable Material, which is particularly advantageous in that the thus formed recesses in contrast to the blind holes 36 according to the generic state of the art (see the FIGS. 11 and 12 ) can be cleaned particularly well by means of, for example, a brush in order to remove remnants of the temporarily deformable material, for example after the blocking of the optical workpiece, and thus to prepare the block piece for its next use.

Furthermore, it can be provided that the inner boundary surface opposite outer boundary surface of the respective recess for receiving the temporarily deformable material is curved away from the inner boundary surface, so that the respective pocket opening like a pocket opens radially outward. The temporarily deformable material can thus easily flow into the respective recess from the outside during the blocking process. In addition, this embodiment of a good cleaning ability of the recesses for receiving the temporarily deformable material is conducive.

In the further pursuit of the inventive concept, the inner boundary surface may be connected to the outer boundary surface of the respective recess for receiving the temporarily deformable material via only an arcuate connecting surface, so that the respective recess expires at its longitudinal ends to the end face of the body in an advantageous manner continuously. The respective recess forms at this point, in contrast to the blind holes 36 in the generic state of the art so no step or corner, which can be difficult to clean by means of, for example, a brush.

The number of recesses for receiving the temporarily deformable material may also be more than two, although it should be noted that with increasing number of recesses both the production cost of the block piece as well as the cleaning effort increases. Thus, the base body may be provided at its end face approximately with three recesses for receiving the temporarily deformable material, which are placed in a symmetrical arrangement about the central axis of the body around, so that the radially inner boundary surfaces of the recesses in a plan view of the end face seen the shape form an isosceles triangle. However, an embodiment of the block piece is preferred, in which the base body is provided at its end face with four recesses for receiving the temporarily deformable material, which are arranged in a symmetrical arrangement about the central axis of the base body, so that the inner boundary surfaces of the recesses forming the undercuts seen in a plan view of the main body form the shape of a square. With such an arrangement of four recesses, compared to a triangular arrangement of three recesses, the structurally usable free area between the recesses is advantageously larger. In addition, in the square-shaped arrangement of the recesses of the frictional engagement between the base body and the temporarily deformable material, which is caused by a pair of parallel aligned recesses as described above and a transverse movement of the temporarily deformable material with respect to the main body in the longitudinal direction of these recesses counteracts, to simple Way superimposed by the other pair of parallel aligned recesses a positive engagement in the longitudinal direction of the first pair, so that any transverse movement of the temporarily deformable material relative to the base body is reliably prevented even under high, acting on the blocked workpiece during its processing external forces.

In principle, the base body of the block piece according to the invention may be provided, as in the generic state of the art, with a central through-hole, for example if it requires the device used for blocking as far as the temporarily deformable material is fed through the block piece through the joint between the block piece and the workpiece. Preferably, however, is a "closed" design of the block piece, in which the base body is provided at its end face between the recesses for receiving the temporarily deformable material substantially centrally with a kugelkalottenförmigen recess, so that the blocked optical workpiece during its processing by the block piece is supported in an often critical, middle range. In this case, compared to a block piece, which also conceivably has a continuous plane end face, an optical workpiece having a Blockstückseitigen convex surface in the blocked state due to the kugelkalottenförmigen recess in the main body face closer to the block piece, so that the workpiece, temporarily deformable material and blocks piece existing processing group in the ratio advantageously short builds. The closer the workpiece sits on the block piece, the less problems can arise in the caused by the block piece flying bearing of the workpiece by imbalances, which in turn is conducive to the achievement of a high machining accuracy.

Furthermore, the base body may be provided at its clamping surface with at least two with respect to the central axis of the body diametrically opposite, preferably conical depressions. These depressions, which can also be formed by providing suitable cross slide in the injection mold in a simple manner during the injection molding of the base body, serve for better automated handling of the blocked workpiece. More specifically, in this embodiment of the block piece, a parallel gripper of a handling device with centering points engage in the depressions to receive the block piece at a predetermined location, to transport a certain distance or to set it down again at a predetermined point.

Furthermore, the block piece can be provided according to the German DIN 58766 with two outgoing from a lower annular surface of the base recesses for centering the block piece on the spindle of the machine, which are diametrically opposed to each other with respect to the central axis of the body and seen in a side view of the body substantially V are -förmig, wherein the recesses are advantageously formed by providing complementary projections in the injection mold during the injection molding of the base body, without requiring a machining of the body requires. In this case, starting from the bottom of each recess for centering the block piece, a blind hole may be formed in the base body - which also expediently takes place during the injection molding of the base body - in which a metallic bearing insert is inserted, which is a ball socket or the like. so that the block piece can also be received on processing machines that engage with tips on the bearing inserts to allow a tilting movement of the block piece about an axis defined by the bearing inserts (see, eg, US Pat DE 40 00 291 A1 ).

In addition, the block piece can be provided with at least one outgoing from a lower annular surface of the base recess for rotation angle orientation of the block piece about the central axis of the body, as known for example from the German standard DIN 58766, with the special feature that this recess by providing a suitable projection in the injection mold, in turn, the same during injection molding of the base body is formed, so that a machining processing of the recess on the base body, as provided in the generic state of the art, advantageously eliminated.

In further pursuit of the inventive concept, the base body may also have a recess into which a so-called "transponder" is inserted. Such a transponder is a semiconductor element known per se, in particular in the prescription production of spectacle lenses, for storing and transmitting information. This can now be used to identify the block piece or the blocked workpiece, the current processing state of the workpiece, etc. In the generic state of the art, integration of such transponders in the block piece as a result of the shielding effect of the metallic base material is not possible. Suitably, the outgoing from a lower annular surface of the main body recess for receiving the transponder in turn during the injection molding of the base body may be the same formed by the injection mold for the main body is again provided at this point with a suitable projection.

Finally, the main body of the block piece may consist of a glass fiber reinforced polyamide. This plastic is characterized in particular by a high impact strength and hardness and a good temperature resistance. Due to the glass fiber reinforcement of the plastic, in particular the mechanically highly stressed clamping surface of the block piece also has a high abrasion resistance, so that additional measures to reduce wear, such as the insertion of a possibly metallic reinforcement in the clamping surface of the body in the injection mold - which in principle also conceivable would be - dispensable.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine perspektivische Ansicht eines erfindungsgemäßen Blockstücks von schräg vorne/oben, welches in einem gegenüber den realen Abmessungen vergrößerten Maßstab dargestellt ist,

Fig. 2

eine perspektivische Ansicht des Blockstücks nach Fig. 1 von schräg hinten/unten im Maßstab gemäß Fig. 1,

Fig. 3

eine Draufsicht auf das Blockstück gemäß Fig. 1 in einem geringfügig kleineren Maßstab, der im Vergleich zu den realen Abmessungen des Blockstücks dennoch eine Vergrößerung darstellt,

Fig. 4

eine Seitenansicht des Blockstücks nach Fig. 1 im Maßstab gemäß Fig. 3,

Fig. 5

eine Unteransicht des Blockstücks nach Fig. 1 im Maßstab gemäß Fig. 3,

Fig. 6

eine Schnittansicht des Blockstücks gemäß Fig. 1 entsprechend der Schnittverlaufslinie VI-VI in Fig. 5,

Fig. 7

eine Schnittansicht des Blockstücks gemäß Fig. 1 entsprechend der Schnittverlaufslinie VII-VII in Fig. 5,

Fig. 8

eine prinzipielle Schnittansicht einer Spritzgießform zur Herstellung eines Grundkörpers für das Blockstück gemäß Fig. 1, die veranschaulicht, wie mittels Querschiebern der Spritzgießform hinterschnittene Aussparungen in einer Stirnfläche des Grundkörpers des Blockstücks ausgebildet werden,

Fig. 9

eine Seitenansicht des Blockstücks nach Fig. 1 in einem gegenüber der Fig. 3 noch kleineren Maßstab, der fast den realen Abmessungen entspricht, mit einer darauf mittels eines temporär verformbaren Materials aufgeblockten Brillenlinse als optisches Werkstück,

Fig. 10

eine Schnittansicht des Blockstücks und der darauf aufgeblockten Brillenlinse gemäß Fig. 9 entsprechend der Schnittverlaufslinie X-X in Fig. 9, wobei auch schematisch angedeutet ist, wie das Blockstück mittels Spannzangen an einer Spindel einer Bearbeitungsmaschine aufnehmbar ist,

Fig. 11

eine im Maßstab gegenüber den realen Abmessungen etwas vergrößerte Draufsicht auf ein Blockstück nach dem Stand der Technik,

Fig. 12

eine Schnittansicht des vorbekannten Blockstücks gemäß Fig. 11 entsprechend der Schnittverlaufslinie XII-XII in Fig. 11,

Fig. 13

eine Unteransicht des vorbekannten Blockstücks nach Fig. 11 im Maßstab gemäß Fig. 11 und

Fig. 14

eine Schnittansicht des vorbekannten Blockstücks gemäß Fig. 11 entsprechend der Schnittverlaufslinie XIV-XIV in Fig. 13.

In the following the invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings. In the drawings show:

Fig. 1

a perspective view of a block piece according to the invention obliquely from the front / top, which is shown in an enlarged compared to the real dimensions scale,

Fig. 2

a perspective view of the block piece after Fig. 1 from obliquely behind / below in the scale according to Fig. 1 .

Fig. 3

a plan view of the block piece according to Fig. 1 on a slightly smaller scale, which is still an enlargement compared to the real dimensions of the block piece,

Fig. 4

a side view of the block piece after Fig. 1 in the scale according to Fig. 3 .

Fig. 5

a bottom view of the block piece after Fig. 1 in the scale according to Fig. 3 .

Fig. 6

a sectional view of the block piece according to Fig. 1 according to the section line VI-VI in Fig. 5 .

Fig. 7

a sectional view of the block piece according to Fig. 1 according to the section line VII-VII in Fig. 5 .

Fig. 8

a schematic sectional view of an injection mold for producing a main body for the block piece according to Fig. 1 which illustrates how undercuts of the injection mold are used to form undercut recesses in an end face of the main body of the block piece,

Fig. 9

a side view of the block piece after Fig. 1 in one opposite Fig. 3 even smaller scale, which corresponds almost to the real dimensions, with a spectacle lens blocked thereon by means of a temporarily deformable material as an optical workpiece,

Fig. 10

a sectional view of the block piece and the spectacle lens blocked thereon according to Fig. 9 according to the section line XX in Fig. 9 , wherein also schematically indicated how the block piece can be accommodated by means of collets on a spindle of a processing machine,

Fig. 11

a somewhat enlarged plan view of a block piece according to the prior art compared to the real dimensions,

Fig. 12

a sectional view of the prior art block piece according to Fig. 11 according to the section line XII-XII in Fig. 11 .

Fig. 13

a bottom view of the prior art block piece after Fig. 11 in the scale according to Fig. 11 and

Fig. 14

a sectional view of the prior art block piece according to Fig. 11 according to the cutting line XIV-XIV in Fig. 13 ,

DETAILED DESCRIPTION OF THE EMBODIMENT

In the Fig. 1 to 7 is a reusable block piece 40 for holding an optical workpiece, in particular a spectacle lens L (see FIGS FIGS. 9 and 10 ), shown for its processing, which comprises a base body 42 having an end face 44 on which the spectacle lens L according to in particular of the Fig. 10 by means of a temporarily deformable material 46 (eg wax or a Wood metal, also called "Alloy" called) is aufblockbar. The base body 42 further has a clamping surface 48, via which the spectacle lens L, which is blocked on the base body 42, can be fixed to a spindle of a processing machine, from the in FIG Fig. 10 Collets 50 are indicated schematically. It is essential that, as will be described in more detail below, the base body 42 is injection molded from plastic and is provided at its end face 44 with at least two recesses 52 for receiving the temporarily deformable material 46, which are arranged on both sides of an imaginary plane contains the central axis M of the base body 42, and their middle axis M of the body 42 respectively proximate, ie radially inner boundary surface 54 forms an undercut which is engaged behind in the blocked state of the spectacle lens L of the temporarily deformable material 46, in particular in the Fig. 10 easy to recognize.

In the end face 44 of the substantially cup-shaped basic body 42, which is preferably made of a glass-fiber-reinforced polyamide, such as PA 6.6 - GF30, it is in particular the case Fig. 4, 6, 7 and 8th around a plane surface, are provided on or starting from the in the illustrated embodiment, four recesses 52 for receiving the temporarily deformable material 46, which, like the Fig. 1 and 3 show, are arranged in a symmetrical arrangement about the central axis M of the base body 42 around. In this case, the inner boundary surface 54 of each recess 52 is flat and extends from the central axis M of the main body 42 spaced approximately over the entire width of the end face 44 of the base body 42, as the Fig. 1 and 3 illustrate, so that the inner boundary surfaces 54 of the recesses 52 in the plan view according to Fig. 3 seen form the shape of a square.

In the Fig. 1 and 3 It will further be appreciated that the inner peripheral surface 54 of each recess 52 opposite, radially outer boundary surface 56 of the respective recess 52 is curved away from the inner boundary surface 54 outwardly, so that each recess 52 pocket-like or mouth-shaped radially outward opens. In particular Fig. 1 the inner boundary surface 54 of each recess 52 is connected to its outer boundary surface 56 via only one arcuate connection surface 58, so that each of the slot-like recesses 52 terminates at its longitudinal ends to the end face 44 of the body 42 towards infinitely. Between the recesses 52 of the base body 42 is finally provided on its end face 44 substantially centrally with a kugelkalottenförmigen recess 60.

The cylindrical clamping surface 48 adjoins the end face 44 of the base body 42 on the outer peripheral side as the diameter-largest section of the block piece 40, which extends approximately over half the height of the block piece 40. On the clamping surface 48, the base body 42 is provided with at least two diametrically opposite with respect to the central axis M of the body 42, in the illustrated embodiment four corresponding to the recesses 52 at 90 ° with respect to the central axis M angularly offset depressions 62, seen in cross section (see Fig. 6 and 10 ) have a conical shape and serve the attack of handling or transport means (not shown) on the block piece 40. The depressions 62 are preferably formed during injection molding of the base body 42 with the aid of transverse slides in the injection mold, although this is to simplify the illustration in Fig. 8 not shown.

The clamping surface 48 is followed by the known conical centering surface 64 of the base body 42 before the base body 42 ends with a flat annular surface 66.

On the inner peripheral side, a central frustoconical blind hole 68 adjoins the lower annular surface 66, the conical surface 70 of which tapers towards the flat bottom 72 of the blind hole 68.

As in the generic state of the art, the block piece 40 is further provided with two outgoing from the lower annular surface 66 of the body 42 recesses 74 for per se known centering of the block piece 40 on the spindle of the processing machine, with respect to the central axis M of the body 42 according to in particular Fig. 2 . 5 . 8 and 10 diametrically opposite each other and in a side view ( Fig. 4 ) of the base body 42 seen tapering toward the clamping surface 48 is substantially V-shaped. In the Fig. 4 It can also be seen that the recesses 74 extend approximately over the entire height of the conical centering surface 64 and are aligned axially with the depressions 62 in the clamping surface 48. The recesses 74 are expediently formed during the injection molding of the base body 42 by suitable projections in the injection mold with.

How the particular Fig. 6 shows, starting from the bottom of each recess 74, a frusto-conical blind hole 76 in the base body 42 is formed, in which a metallic bearing insert 78 is firmly inserted, preferably glued, which has a ball socket 80 in the illustrated embodiment. The blind holes 76 are formed during injection molding of the body 42 with the same. The optional bearing inserts 78 serve with their ball sockets 80 of the recording of spindle-side bearing tips (not shown), which are provided on certain processing machines (see for example the DE 40 00 291 A1 ), and define a pivot axis about which a tilting movement of the block piece 40 is possible in these processing machines.

Furthermore, the base body 42 is provided, starting from the lower ring surface 66 with a coding recess 82 for rotational angle orientation of the block piece 40 about the central axis M, as described above with reference to the Fig. 11 to 14 has already been explained for the generic state of the art. In the illustrated embodiment, the block piece 40 according to in particular the FIGS. 5 and 7 Also, a second, cylindrical Codier-recess 84 which extends from the lower annular surface 66 of the body 42 in this parallel to the central axis M in and on another type of processing machine for rotational angular orientation of the block piece 40 around the central axis M. Both Codier-recesses 82, 84 are also formed during the injection molding of the body 42 by suitable projections in the injection mold with.

In the illustrated embodiment, the block piece 40 is further provided with a known, in Fig. 7 merely schematically drawn, so-called "transponder" 86 equipped for workpiece identification. For receiving the transponder 86, the base body 42 has a further, cylindrical recess 88, which extends from the lower annular surface 66 of the base body 42 parallel to the central axis M in this in and according to Fig. 7 almost reaches one of the recesses 52 for receiving the temporarily deformable material 46. This recess 88 is preferably formed during the injection molding of the base body 42 by a suitable projection in the injection mold with the same.

Finally, the base body 42 has in its lower annular surface 66 according to the Fig. 2 and 5 nor a ring-segment-shaped, formed during the injection molding of the body 42 recess 90 between one of the centering recesses 74 and the recess 88 for the transponder 86, the like as a text box for a stamping marking or the like. of the block piece 40 is used.

The Fig. 8 shows the two mold halves 92, 94 of the injection mold for the main body 42 of the block mold 40 in the closed state of the injection mold, with already injection-molded body 42. In the upper mold half 92 of the injection mold suitably profiled cross slide 96 are shown schematically, the formation of the undercut recesses 52nd serve in the end face 44 of the base body 42. The double arrows on the cross slides 96 illustrate the movement possibilities of the cross slides 96. It will be appreciated by those skilled in the art that the cross slides 96 will protrude into the cavity defined by the mold halves 92, 94 in the injection mold during the spiking operation, around the undercut recesses 52 in the end face 44 of the body 42, and after solidification of the plastic in the injection mold from the recesses 52 produced on the base 42 are pulled out, so that the main body 42 can be formed from the injection mold. It requires at this point for the expert no further explanation, such as by providing suitable projections (or other cross slide for the depressions 62) in the injection mold next to the recesses 52 on the end face 44 of the body 42 in a Spitzgieß operation and all other wells , Depressions, recesses, blind holes, etc. (60, 62, 74, 76, 82, 84, 88, 90) can be formed in an extremely cost-effective manner with.

The actual block process, the result in the FIGS. 9 and 10 shown and its course is well known to those skilled in the art, so that relevant embodiments are dispensable at this point, it should be noted that the temporarily deformable material 46 in the described embodiment of the block piece 40 in the block device from radially outside between the spectacle lens L and the Block piece 40 is supplied to connect these parts together. In this case, the temporarily deformable material 46 flows due to the Pocket-like opening of the recesses 52 in the end face 44 of the body 42 easily into this. The shrinkage associated with the solidification of the temporarily deformable material 46, due to the described arrangement of the undercut surfaces 54, then results in a firm anchoring or clamping of the temporarily deformable material 46 to the block piece 40.

LIST OF REFERENCE NUMBERS

10

block piece

12

body

14

face

16

clamping surface

18

centering

20

ring surface

22

Through Hole

24

first cone surface

26

second cone surface

28

annular shoulder

30

third cone surface

32

recess

34

recess

36

blind hole

40

block piece

42

body

44

face

46

temporarily deformable material

48

clamping surface

50

collet

52

recess

54

inner boundary surface

56

outer boundary surface

58

interface

60

deepening

62

depression

64

centering

66

ring surface

68

blind

70

conical surface

72

ground

74

recess

76

blind

78

bearing insert

80

ball socket

82

recess

84

recess

86

transponder

88

recess

90

deepening

92

mold

94

mold

96

cross slide

L

eyeglass lens

M

central axis

Claims (13)

1. Block piece (40) for holding an optical workpiece, in particular a spectacle lens (L), for machining thereof, comprising a basic body (42)
   which has an end face (44), against which the workpiece can be blocked by means of a temporarily deformable material (46), said end face (44) facing towards the blocked workpiece, and
   a clamping face (48) that adjoins said end face (44) at the outer circumference and via which the workpiece blocked on said basic body (42) can be fixed on a spindle (50) of a machining machine,
   characterized in that said basic body (42) injection-molded from plastic is provided on its end face (44) with at least two cut-outs (52) for receiving the temporarily deformable material (46), said cut-outs being arranged on either side of an imaginary plane which contains the center axis (M) of said basic body (42), and the boundary face (54) of said cut-outs which is closest to the center axis (M) of said basic body (42) in each case forms an undercut.
2. Block piece (40) according to Claim 1, characterized in that the inner boundary face (54) of the respective cut-out (52) for receiving the temporarily deformable material (46), in each case closest to the center axis (M) of said basic body (42), is essentially flat and extends at a distance from the center axis (M) of said basic body (42) more or less over the entire width of said end face (44) of said basic body (42).
3. Block piece (40) according to Claim 2, characterized in that the outer boundary face (56) of the respective cut-out (52) for receiving the temporarily deformable material (46), opposite the inner boundary face (54), is curved away from the inner boundary face (54).
4. Block piece (40) according to Claims 2 and 3,
   characterized in that the inner boundary face (54) is connected to the outer boundary face (56) of the respective cut-out (52) for receiving the temporarily deformable material (46) via just one curved connecting face (58).
5. Block piece (40) according to any of Claims 2 to 4, characterized in that said basic body (42) is provided on its end face (44) with four cut-outs (52) for receiving the temporarily deformable material (46), which cut-outs are arranged in a symmetrical arrangement about the center axis (M) of said basic body (42) so that the inner boundary faces (54) of the cut-outs (52), which inner boundary faces form the undercuts, form the shape of a square when seen in a plan view (Fig. 3) of said basic body (42).
6. Block piece (40) according to any of the preceding claims, characterized in that said basic body (42) is provided on its end face (44), between the cut-outs (52) for receiving the temporarily deformable material (46), with a spherical depression (60) essentially in the center of said end face.
7. Block piece (40) according to any of the preceding claims, characterized in that said basic body (42) is provided on its clamping face (48) with at least two preferably conical hollows (62) which are diametrically opposed with respect to the center axis (M) of said basic body (42).
8. Block piece (40) according to any of the preceding claims, characterized in that two cut-outs (74) for centering the block piece (40) on the spindle (50) of the machining machine are formed during the injection-molding of said basic body (42), said cut-outs starting from a lower annular face (66) of said basic body (42) and being diametrically opposed from one another with respect to the center axis (M) of said basic body (42) and being essentially V-shaped in a side view (Fig. 4) of said basic body (42).
9. Block piece (40) according to Claim 8, characterized in that, starting from the base of each cut-out (74) for centering the block piece (40), a blind hole (76) is formed in said basic body (42), with a metal bearing insert (78) which has a ball pan head (80) or the like being inserted into said blind hole.
10. Block piece (40) according to any of the preceding claims, characterized in that at least one cut-out (82, 84) for rotation angle orientation of the block piece (40) about the center axis (M) is formed during the injection-molding of said basic body (42), said cut-out starting from a lower annular face (66) of said basic body (42).
11. Block piece (40) according to any of the preceding claims, characterized in that said basic body (42) has a cut-out (88) into which a transponder (86) for identifying the optical workpiece is inserted.
12. Block piece (40) according to Claim 11, characterized in that the cut-out (88) for receiving said transponder (86) is formed during the injection-molding of said basic body (42), said cut-out starting from a lower annular face (66) of said basic body (42).
13. Block piece (40) according to any of the preceding claims, characterized in that said basic body (42) is made of a glass-fiber-reinforced polyamide.

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