EP1864753B1 - Machine for machining optical workpieces, especially plastic spectacle lenses - Google Patents

Description

TECHNICAL AREA

The present invention relates to a machine for processing optical workpieces, in particular plastic spectacle lenses, according to the preamble of patent claim 1.

STATE OF THE ART

Conventionally, in the processing of plastic spectacle lenses, there is a plastic injection-molded spectacle lens blank, also called a blank, which has a standardized finished convex outer surface with e.g. spherical, aspherical or progressive form. The generally concave inner or prescription surfaces receive a spherical, aspherical, toric, atoric, progressive or freeform geometry (progressive surfaces) by means of machining, depending on the desired optical effect. The typical conventional process of internal surface working, after blocking the lens blank with its outer surface on a block piece, provides a milling or turning process for producing the optically active mold, usually followed by a finish grinding or polishing process to achieve the necessary surface finish a turned-eyeglass lens but also can be dispensable.

For the turning process also so-called fast-tool lathes are used in the prior art, in which a turning tool either linear reciprocating (see, eg, the WO-A-02/06005 or the generic WO 97/13603 ) or rotary (see, for example, the WO-A-99/33611 ) can be moved highly dynamically, so that non-rotationally symmetric lens surfaces can be produced in the turning process with very good surface qualities.

After the spectacle lens surface having the desired optical effect has been produced, the spectacle lens must be used in particular for subsequent processing, namely the so-called "edging", i. the edge processing of the spectacle lens for adaptation to the respective spectacle frame, are provided with a label. So, for example, a progressive lens according to DIN EN ISO 8980-2 be permanently marked with at least the following information: a) marking for alignment; this must consist of at least two marks at a distance of 34 mm and be arranged symmetrically to a vertical plane through the fitting point or the prism reference point; b) indication of the additional effect, in diopters; and c) an indication of the manufacturer or supplier or the trade name or trade mark. As optional, non-permanent markings, this standard also recommends further markings for alignment, for the distance reference point, for the near reference point, for the fitting point and for the prism reference point.

While the permanent markings are usually made by permanent engravings, of which the functional engravings, i. the engravings required by the optician for the alignment and assignment of the respective spectacle lens are usually performed so finely that they are not visible under normal light with the naked eye, the non-permanent markings are e.g. executed by means of a temporary stamp image, which is removed in the course of finishing the lens.

In addition, some eyeglass lens manufacturers also offer permanent individual engravings on the spectacle lens, eg the engraving of the initials of the spectacle lens wearer, which is intended to emphasize the customization of the spectacle lenses and at one point of the lens is placed where it does not affect the vision.

The permanent engravings are usually applied in an engraving machine separate from the actual processing machine, in which a rotationally driven engraving tool with geometrically determined cutting edge (milling tool) or geometrically indefinite cutting edge (grinding tool) is guided in defined machining engagement over the spectacle lens surface to be marked to form the engraving. However, engraving machines are also known in which the engraving is applied to the spectacle lens by means of a laser beam.

In order to avoid the additional use of special diamond tools or high-energy laser radiation for the attachment of markings on the lens surface, suggests the generic WO 97/13603 These markings during the machining process by means of the tool, with which the turning is done, directly zuzuerzeugen, so that all reproducibility problems, as they occur at each machine change, should be omitted. For the actual turning this tool must have a rotary cutter with a defined cutting geometry. With such a rotary cutter, however, only markings can be produced which consist of fine lines running parallel to the cutting edge. It would be desirable if here, as in the known engraving machines, any graphic symbols, such as letters, numbers, company logos, etc., could be generated in detail.

PRESENTATION OF THE INVENTION

Based on the state of the art according to the WO 97/13603 The invention is based on the object, a machine for processing optical workpieces, in particular of plastic spectacle lenses be provided with a fast-tool arrangement, by means of which also any finely detailed markings can be attached to the workpiece, without requiring the workpiece to be re-clamped or.

This object is achieved by the features specified in claim 1. Advantageous and / or expedient developments of the invention are subject matter of the claims 2 to 5.

According to the invention, in a machine for processing optical workpieces, in particular of plastic spectacle lenses, which has a workpiece spindle, by means of which the workpiece is rotatably drivable about a workpiece axis of rotation, and a first fast tool arrangement, by means of a turning tool in the direction the workpiece spindle and the fast tool assembly are also movable in a direction transverse to the workpiece axis of rotation relative to each other, in addition to and preferably in parallel with the first fast tool assembly, a second fast tool -Anordnung provided with a Engraving stylus, which has a tapered toward its workpiece towards the end tip, so that its end facing the workpiece is substantially punctiform, the engraving stylus by means of the second Fast tool assembly highly dynamic in the direction of the workpiece and away from it, so that by needles Engagement of Engierstichels with the workpiece at this a mark can be generated.

With the next to the first fast tool assembly arranged in parallel second Fast tool arrangement that drives the engraving stylus, thus can be provided in the working space of one and the same machine immediately after the actual turning the workpiece with a permanent engraving Without this, the workpiece must be reloaded on a separate engraving machine, which is conducive to a fast and accurate machining process. There In this case, a different tool from the turning tool is used, namely the engraving stylus whose end facing the workpiece is substantially punctiform, unlike the generic state of the art, the producible geometry of the mark is not limited by the geometry of the turning tool. By needling engagement of the pointed engraving stylus with the workpiece, ie an engraving, in which the engraving stylus like a woodpecker on a tree in rapid succession impinges on the workpiece, can produce very finely detailed engravings. Furthermore, in the machine according to the invention, the engraving of the workpiece does not result in wear on the turning tool, as well as the turning of the workpiece causes no wear on the engraving stylus, which increases the tool life compared to the generic state of the art. This is especially important in view of the fact that a blunt engraving stylus may only push away the material of the workpiece during engraving, but then the material will gradually return, which causes undesirable "aging" or "fading", especially in the case of the plastic material CR39 "of the engraving picture can lead.

In an advantageous embodiment of the machine, in which the engraving stylus is movable by means of the second fast tool arrangement in a fast tool movement plane, while the workpiece spindle and the second fast tool arrangement are movable in a plane relative to each other, which Contains workpiece axis of rotation, the fast tool movement plane may be inclined with respect to the plane containing the workpiece axis of rotation by an angle. Due to the inclination of the plane of movement of the fast tool such that between this plane of movement and the workpiece axis of rotation containing plane, thus the workpiece axis of rotation of the workpiece spindle an angle of predetermined size is present in connection with the (anyway) on the Machine existing Zustell (relative) movement the workpiece spindle in the plane containing the workpiece rotation axis, more precisely in the direction of the workpiece spindle achieve a highly accurate height adjustment of the workpiece-facing, substantially punctiform end of the engraving stylus on the workpiece axis of rotation of the workpiece spindle, without causing height displacements of Engierstichels with respect to the Fast tool Arrangement and corresponding mechanical adjusting systems for adjusting the height of the engraving stylus are required. The degree of Zustell (relative) movement of the workpiece spindle in the direction of its axis and thus the height compensation achieved thereby between the workpiece axis of rotation of the workpiece spindle and the operating point of Engierstichels takes place in accordance with the sine function of the predetermined angle. All this is to achieve a high positional accuracy of the marking on the workpiece by simple means conducive; for example, a freeform surface engraving is the primary mark of the surface and must therefore be mounted with high accuracy, the allowable tolerance is about +/- 0.2 mm.

In view of the sensitivity of the height adjustment of the workpiece facing the end of the engraving stylus with respect to the workpiece axis of rotation, it is preferred if the fast tool movement plane and the plane containing the workpiece rotation axis include an angle of attack which is between 2 ° and 10 ° ,

Although it is preferred in particular with regard to the simplest possible mathematics in the control of the axes of movement when the engraving stylus by means of the second fast tool arrangement - like the turning tool in the first fast tool arrangement - positionally controlled in the axial direction undeliverable, the basic idea of the present invention, namely the parallel arrangement of a second Fast-tool arrangement carrying an engraving stylus to the first fast tool arrangement for the turning tool, also on a machine with a rotary Fast-Tool arrangement for the turning tool, as they say from the WO-A-99/33611 is known to be realized, in which case a second rotary fast tool arrangement would be used for the engraving stylus. In this case, the common fast tool motion plane would be perpendicular to the pivot axes of the rotary fast tool assemblies.

Finally, depending on the material of the workpiece to be marked, various materials, e.g. Hardened steel, conceivable for the tip of the engraving stylus. However, in view of the longest possible service life of the engraving stylus in the processing of plastic spectacle lenses, it is preferred if the tip of the engraving stylus facing the workpiece is made of hard metal.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine perspektivische Ansicht einer erfindungsgemäßen Maschine zur Bearbeitung von optischen Werkstücken, namentlich Kunststoff-Brillengläsern, von schräg vorne/oben, die werkzeugmäßig mit einer Fräseinheit und zwei Fast-Tool-Anordnungen ausgestattet ist;

Fig. 2

eine perspektivische Ansicht der Maschine gemäß Fig. 1 von schräg hinten/oben;

Fig. 3

eine nach unten abgeschnittene Vorderansicht der Maschine gemäß Fig. 1;

Fig. 4

eine nach unten abgeschnittene Vorderansicht der Maschine gemäß Fig. 1, die sich von der Darstellung in Fig. 3 dahingehend unterscheidet, daß eine Frässpindel der Fräseinheit teilweise abgeschnitten dargestellt ist, um den Blick auf die dahinter liegende Fast-Tool-Anordnung freizugeben;

Fig. 5

eine Draufsicht auf die Maschine gemäß Fig. 1 mit Blickrichtung von oben in den Fig. 3 und 4;

Fig. 6

schematische Vorderansichten einer Werkstückspindel der Maschine gemäß Fig. 1, an der ein im Querschnitt dargestelltes Brillenglas montiert ist, welches mittels eines Drehmeißels der Fast-Tool-Anordnung bearbeitet wird, wobei im oberen Teil von Fig. 6 eine fehlerhafte Höhenjustage des Drehmeißels bezüglich der Werkstück-Drehachse der Werkstückspindel veranschaulicht ist, während im unteren Teil von Fig. 6 eine korrekte Höhenjustage des Drehmeißels bezüglich der Werkstück-Drehachse gezeigt ist, zur Erläuterung des Prinzips der Höhenkalibrierung von Drehmeißel und Gravierstichel an der in den Fig. 1 bis 5 dargestellten Maschine;

Fig. 7

eine vergrößerte Seitenansicht des in den Fig. 2 und 5 nur schematisch dargestellten Gravierstichels der Maschine, in einem von der Maschine getrennten Zustand; und

Fig. 8

eine Draufsicht auf ein Brillenglas, welches mit der erfindungsgemäßen Maschine dauerhaft graviert wurde.

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

Fig. 1

a perspective view of a machine according to the invention for the processing of optical workpieces, namely plastic spectacle lenses, obliquely from the front / top, which is equipped with a milling unit tool and two fast-tool arrangements;

Fig. 2

a perspective view of the machine according to Fig. 1 from diagonally back / up;

Fig. 3

a cut down front view of the machine according to Fig. 1 ;

Fig. 4

a cut down front view of the machine according to Fig. 1 that differ from the representation in Fig. 3 differs in that a milling spindle of the milling unit is shown partially cut off to release the view of the underlying fast tool arrangement;

Fig. 5

a plan view of the machine according to Fig. 1 with view from above in the Fig. 3 and 4 ;

Fig. 6

schematic front views of a workpiece spindle of the machine according to Fig. 1 on which a spectacle lens shown in cross-section is mounted, which is machined by means of a turning tool of the fast tool arrangement, wherein in the upper part of Fig. 6 a faulty height adjustment of the turning tool with respect to the workpiece axis of rotation of the workpiece spindle is illustrated, while in the lower part of Fig. 6 a correct height adjustment of the turning tool is shown with respect to the workpiece axis of rotation, to explain the principle of the height calibration of turning tool and engraving stylus on in the Fig. 1 to 5 represented machine;

Fig. 7

an enlarged side view of the in the Fig. 2 and 5 Engraving stylus of the machine shown only schematically, in a separate state from the machine; and

Fig. 8

a plan view of a spectacle lens which has been permanently engraved with the machine according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

The Fig. 1 to 5 show a schematic representation of a CNC-controlled machine 10 in particular for surface treatment of lenses L made of plastic in a rectangular Cartesian coordinate system in which the small letters x, y and z the width direction (x), the length direction (y) and the height direction (z) of the machine 10. The machine 10 as such, without engraving, was already in the earlier German patent application 10 2005 021 640.4 the same applicant described.

According to the Fig. 1 to 5 the machine 10 has a machine frame 12 which limits a processing area 14. On the in Fig. 1 left side of the processing area 14, two guide rails 16 extending in the (horizontal) width direction x parallel to each other, on an in Fig. 1 attached to the upper mounting surface 17 of the machine frame 12. An X-carriage 18, which is CNC-positionally adjustable by associated CNC drive and control elements (not shown) in both directions of an X-axis, is slidably mounted on the guide rails 16.

Two further guide rails 20, which extend in the (also horizontal) longitudinal direction y parallel to each other and perpendicular to the guide rails 16, are located on an in Fig. 1 attached to the upper mounting surface 21 of the X-carriage 18. In a cross table assembly, a Y-carriage 22 is slidably mounted on the guide rails 20, which is CNC-controlled by associated CNC drive and control elements (also not shown) in both directions of a Y-axis.

At one in the Fig. 1 to 4 lower mounting surface 23 of the Y-carriage 22 is a workpiece spindle 24 is fixed, which is rotationally driven by means of an electric motor 26 in the rotational speed and the rotation angle CNC-controlled about a workpiece axis of rotation B. The workpiece rotation axis B is aligned with the Y axis. On the workpiece spindle 24, more precisely its end projecting into the machining area 14, the spectacle lens L blocked on a block piece is mounted in a manner known per se for machining in particular the prescription surface R of the spectacle lens L in such a way that it can rotate coaxially with the workpiece spindle 24.

From the above description, it can be seen so far that the workpiece spindle 24 by means of the X-stage assembly (X-slide 18, Y-slide 22) is CNC-position-controlled in an XY plane movable, which contains the workpiece axis of rotation B and to which the mounting surfaces 17th , 21 and 23 are parallel, while the lens L in rotational speed and rotation angle CNC-controlled about the workpiece axis of rotation B is rotatable.

On the in Fig. 1 Right side of the processing area 14 is now first a milling unit 28 mounted on the machine frame 12, as shown in the EP-A-0 758 571 the same applicant in structure and function is known in principle. The milling unit 28 has a milling spindle 32, which can be driven in a speed-controlled manner by means of an electric motor 30 about a milling cutter rotation axis C, at the end of which a milling tool 34 is mounted in the end projecting into the machining area 14.

By means of the milling unit 28, a milling machining operation can be performed on the lens L, which - according to the teaching of EP-A-0 758 571 - Includes a plunge-cutting operation, wherein the speed-controlled about the cutter rotation axis C rotating milling tool 34 and the rotation angle controlled about the workpiece axis of rotation B rotating spectacle L are moved in at least one of the two axial directions X and Y such position controlled relative to each other that the cutting edges of the milling tool 34 at least in the region of the outer edge of the lens L produce an annular recess recess before the milling tool 34 in a shaping operation along a spiral Way by controlling the trajectory of the lens L in the X and Y axes, that is guided in the XY plane on the lens L from outside to inside to remove more material. Random machining and the faceting of the spectacle lens L are optional, although preferably mitlaufende operations in this milling process L. In the edge processing can be made by means of the rotating milling tool 34 (pre) processing of the lens blank, for example, on a peripheral contour, which predetermined by the spectacle frame shape circumferential contour already largely corresponds, while in the faceting the upper or inner peripheral edge of the lens blank can be bevelled by means of the rotating milling tool 34. These process steps are well known to those skilled in the art, so that will not be discussed further here at this point.

In the Fig. 1 . 3 and 4 behind the milling unit 28 (at least) two fast tool arrangements 36, 38 are provided in parallel arrangement (more than two fast tool arrangements are basically also conceivable). How about from the WO-A-02/06005 is known, each fast tool assembly 36, 38 an actuator 40, 42 and a respective associated shuttle 44, 46 (also called "shuttle") on. The internal structure of the fast tool assemblies 36, 38 shown here is in the earlier German patent application 10 2005 052 314.5 The same applicant described in detail, which is hereby incorporated herein by reference. While the pendulum part 44 of the first fast tool assembly 36 is axially movable in both directions of a fast tool axis F1 by means of the actuator 40, the pendulum part is 46 of the second fast tool assembly 38 by means of the actuator 42 in both directions of a parallel to the first fast tool axis F1 second fast tool axis F2 axially movable. Here, the position or the stroke of the pendulum parts 44, 46 independently adjustable by means of CNC. As the Fig. 5 1, the fast tool axis F1, the fast tool axis F2, the Y axis, and the workpiece rotation axis B are in the same direction as seen in plan view. In the front view according to the Fig. 3 . 4 and 6 seen, however, the direction of the Y-axis and the workpiece axis of rotation B on the one hand differs from the direction of the fast tool axis F1 and the fast tool axis F2 on the other hand, which will be explained in more detail below.

While the pendulum part 44 of the milling unit 28 closer to the first Fast-tool assembly 36 carries at its end projecting into the processing area 14 a turning tool 48 which preferably fixed to the shuttle 44 in a manner not shown here fixed (as opposed to adjustable) is, carries the pendulum part 46 of the second fast tool assembly 38 at its projecting into the processing area 14 end an engraving stylus described in more detail below 50, the end of the lens L facing 51 is substantially point-shaped. As a result, both the turning tool 48 and the engraving stylus 50 are movable in a fast-tool moving plane (X-F1 plane and X-F2 plane, respectively).

In particular Fig. 6 is on the turning tool 48, a cutting plate 52, if necessary, releasably attached or as a coating forming a cutting edge 54 and the respective requirements, in particular specific for the material to be machined, polycrystalline diamond (PCD), CVD, natural diamond or even carbide with or without wear protection coating can exist.

By means of the first fast tool arrangement 36, the pre-processed by the milling unit 28 prescription surface R of the lens L can be post-processed, which in turn regulating the movement of the lens L in the X-axis and possibly the Y-axis, ie in the XY plane, under the control of the movement of the machining turning tool 48 in the F1 axis, ie in the X-F1 plane and under control of the rotational movement of the lens L about the workpiece axis of rotation B. Here, the fast tool assemblies 36 and 38 can be controlled such that the not involved in the turning shuttle member 46 moves to the participating in the turning swinging member 44 in the opposite direction, so that the pendulum parts quasi counter-swing or in push-pull to To prevent by mass compensation that disturbing vibrations are transmitted to the machine frame 12 and to reduce these, as shown in the WO-A-02/06005 is disclosed. As a result, surface qualities that are almost equivalent to the surface quality that can be achieved with conventional polishing methods can be achieved during turning.

As has already been mentioned more generally above, the fast tool arrangements 36 and 38 are mounted on a mounting surface 56 of the machine frame 12, which with respect to the mounting surfaces 17, 21 and 23 for the XY table arrangement (X-carriage 18, Y-slide 22 ) or the workpiece spindle 24 is tilted or set at an angle α, so that the fast tool movement plane (X-F1 plane or X-F2 plane) with respect to the movement plane containing the workpiece rotation axis B (XY) Level) of the workpiece spindle 24 is tilted. This angle α is in the illustrated embodiment about 5 °, but can also be slightly more or less, for example, in the range of 2 ° to 10 °.

By this measure, an adjustment of the turning tool 48 by means of the fast tool assembly 36 in the F1 axis or a Adjustment of the engraving stylus 50 by means of the fast tool assembly 38 in the F2 axis with the result that the movement of the cutting edge 54 of the turning tool 48 and the substantially punctiform end 51 of the engraving stylus 50 receives two components of movement, namely a component of movement in the longitudinal direction The latter can be used to align the operating point of the cutting edge 54 of the turning tool 48 and the end 51 of the engraving stylus 50 to the workpiece rotation axis B of the workpiece spindle 24. Hereby, height errors or deviations of the cutting edge 54 of the turning tool 48 in the height direction z can be compensated; also for the substantially point-shaped end 51 of the engraving stylus 50 can be easily found or adjusted a height reference position in which the end 51 of the engraving stylus 50 in the workpiece axis of rotation B containing (horizontal) level. Such a procedure for the turning tool 48 is in Fig. 6 illustrated.

In the upper part of Fig. 6 a faulty height adjustment of the turning tool 48 is shown. Although here a relative delivery of workpiece spindle 24 and turning tool 48 in the longitudinal direction y takes place such that the lens L at the end of the turning (left-handed turning tool 48) has a thickness in the longitudinal direction y, the desired thickness, ie the desired final thickness d _{s of} the spectacle lens L, a surface error remains in the form of an in Fig. 6 Excessively large illustrated pin 58 on the prescription surface R. This surface defect is due to the fact that the turning tool 48, more precisely its cutting edge 54 at the end of the turning operation, the workpiece rotation axis B does not "hits", but below the workpiece rotation axis B comes to a halt ( with faulty axial position y _{e of} the workpiece spindle 24: tool 48 is too low at the end of the turning operation). A comparable conical surface defect arises (not shown) when at the end of the turning process the cutting edge 54 of the turning tool 48 comes to a stop above the workpiece rotation axis B (tool too high).

In the lower part of Fig. 6 is now a correct height adjustment of the turning tool 48 with respect to the workpiece axis of rotation B shown, in which on the prescription surface R of the lens L no central area error remains. For this purpose, the procedure is as follows: First, - with a known position of the cutting edge 54 of the turning tool 48 in the coordinate system of the machine 10 and known angle α of the fast tool axis F1- calculated an axial position y _{k of} the workpiece spindle 24 in the longitudinal direction y, in which the Operating point of the cutting edge 54 of the turning tool 48 at target end thickness d _{s of} the lens to be processed L in the workpiece axis of rotation B containing XY plane comes to rest, ie the workpiece axis of rotation B "hits". Then, the workpiece spindle 24 is brought by position-controlled axial method or in the Y-axis in the calculated axial position y _k , whereupon an axial setting or holding the workpiece spindle 24 in the calculated axial position y _k occurs. Now, the rotationally driven spectacle lens L can be processed under position-controlled transverse feed of the workpiece spindle 24 in the X-axis and position-controlled (F1-axis) infeed of the turning tool 48 in the fast tool movement plane, ie the X-F1 plane until the target Final thickness d _s on the processed spectacle lens L is achieved. At the end of the turning operation, the cutting edge 54 of the turning tool 48 now "hits" the workpiece rotation axis B automatically.

Alternatively, the procedure may be such that the workpiece spindle 24 is not held in the Y-axis, but in addition to the movement of the fast tool assembly 36 in the F1 axis, a geometry-generating movement of the workpiece spindle 24 in the Y-axis, more precisely, the geometry generation on the Y-axis and the F1-axis is divided such that the Y-axis is responsible for the slower motion component, while the F1 axis takes over the faster motion component. The advantage of this in the older German patent application 10 2005 021 640.4 The procedure described in greater detail in the Applicant's specification is, in particular, that a fast tool arrangement 36 with a smaller stroke and thus greater rigidity can be used and, in addition, higher processing speeds can be achieved.

Although in the described embodiment, the XY plane is horizontal, while the X-F1 plane and the X-F2 plane is tilted out of the horizontal by the angle α, the conditions can basically be taken in reverse, with a horizontal X. -F1 plane or X-F2 plane and an XY plane set at an angle relative to the horizontal plane. Also conceivable is a configuration in which both the X-Y plane and the X-F1 plane or X-F2 plane are tilted out of the horizontal, but then by different angle amounts.

The Fig. 7 shows the in the Fig. 2 and 5 Engraving stylus 50 shown only schematically in a scale enlarged in relation to the reality in detail. The engraving stylus 50 has a cylindrical base body 60 made of steel, which is mounted on its in Fig. 7 left side is provided with a central threaded projection 62. By means of the threaded projection 62, the engraving stylus 50 can be attached to the pendulum part 46 of the second fast tool assembly 38, for which purpose the threaded projection 62 is screwed into a threaded bore (not shown) formed on the face side on the pendulum part 46 and complementary to the threaded neck 62. In order to tighten the engraving stylus 50 on the pendulum part 46, the base body 60 is provided with a transverse bore 64 through which a tool, such as a screwdriver can be inserted, so that the engraving stylus 50, a sufficiently large torque can be applied. Alternatively, the base body 60 on the outer circumference could also with a key surface be provided. The main body 60 ends on the in Fig. 7 From the end face 68, an end portion 70 of the engraving stylus 50 extends away, which terminates after a cylindrical mounting portion 72 with a tapered towards the end 51 of the engraving stylus 50 point 74. Although the end portion 70 may be integrally formed with the base body 60 and possibly hardened at the tip 74, a configuration is preferred in which the end portion 70 is made of hard metal. Accordingly, the base body 60, starting from the end face 68, is provided with a blind bore (not shown) in which the end portion 70 is fastened as an insert coaxially to the base body 60, for example with the aid of a solder joint.

Immediately after the above-described turning of the lens L this is engraved on its recipe surface R by means of the engraving stylus 50 driven by the second fast tool assembly 38. Its position relative to the workpiece spindle 24, more precisely the position of the substantially punctiform end 51 of the engraving stylus 50 with respect to the workpiece axis of rotation B of the workpiece spindle 24 (in the x and z directions) and in the y direction, has previously been calibrated. Such a calibration can for example be such that prior to machining of workpieces with the machine 10, a calibration piece (not shown) in the receptacle of the workpiece spindle 24 is mounted, in such a way that the calibration piece in the coordinate system of the machine 10 is a predetermined position in the x, y and z directions. The calibration piece has, for example, a spherical surface with a known spherical radius. To calibrate the engraving stylus 50, the workpiece spindle 24 is moved by means of the Y-carriage 22 in a predetermined y-position and fixed there. This is followed by the workpiece spindle 24 in a predetermined Rotation position about the workpiece axis of rotation B held calibration piece with the end 51 of Engierstichels 50 at four or more spaced apart in x-direction points "probed", ie the engraving stylus 50 is at four or more different x-positions of the X-carriage 18 and so that the workpiece spindle 24 by means of the second fast tool assembly 38 slowly delivered in the F2 axis until the end 51 of the engraving stylus 50 touches the calibration. This leads in each case to a by means of the measuring system (not shown) of the second fast-tool arrangement 38 indirectly detectable increase in force on the pendulum part 46; the respective F2 position of the pendulum part 46 and thus of the engraving stylus 50 at the time of the force increase is stored in the control unit (not shown) of the machine 10. The contact position can also be determined, for example, by a momentary increase in the following error of the F2 axis, ie a momentary increase in the difference between the setpoint stroke of the pendulum part 46 and its actual stroke, which is detected by CNC technology. After probing the four or more points spaced apart in the x-direction on the spherical surface of the calibration piece, this is rotated by the workpiece spindle 24 by 180 ° in order to compensate for any eccentricity of the spherical surface with respect to the workpiece axis of rotation B. Then a re-probing of the calibration piece takes place at four or more points spaced apart in the x-direction on the spherical surface of the calibration piece; the respective associated F2 position of the shuttle 46 is again stored. From the F2 positions determined and stored in this way, the (relative) position of the end 51 of the engraving stylus 50 in the coordinate system of the machine 10 can be determined in the X, Y and B axes and known spherical radius of the surface of the calibrating piece be calculated in a manner known to those skilled in the art.

The engraving process immediately following the above-described turning operation of the spectacle lens L now proceeds as follows follows. In addition to the (relative) position of the end 51 of the engraving stylus 50 in the coordinate system of the machine 10, the position at which the engraving is to be applied to the prescription surface R of the spectacle lens L is known, as well as the geometry of the engraving tool 48 attached to the spectacle lens L. Recipe area R. From this, the (engraving) positions for the X, Y and B axes are calculated. The positions in the X and B axes are given by the polar coordinates of the engraving to be applied with respect to the axis of rotation of the lens L and its horizontal, ie the workpiece spindle 24 by means of the X-carriage 18 in the X-axis corresponding to the radial distance to be attached Engraving with respect to the axis of rotation of the lens L defined linearly, while the workpiece spindle 24 is rotated about the workpiece axis of rotation B according to the angular position of the applied engraving with respect to the axis of rotation and horizontal of the lens L defined. The defined adjustment of the workpiece spindle 24 in the Y-axis by means of the Y-slide 22 is carried out in accordance with the thickness of the lens L also known from the above information at the point of the recipe surface R to which the engraving is to be attached, in such a way that a position in the Y-axis is approached, in which the end 51 of the means of the second fast tool assembly 38 linearly driven engraving stylus 50 touches the prescription surface R just at the time when it on the workpiece axis of rotation B containing XY Level "meets" or is at the same level. The depth of the engraving can be adjusted by a suitable (more) delivery of Engierstichels 50 in the F2 axis.

As already mentioned, the engraving stylus 50 can now be moved highly dynamically in the direction of the spectacle lens L and away therefrom by means of the second fast-tool arrangement 38, with the end 51 of the engraving stylus 50 in need of needle punching, ie like a woodpecker on a tree in rapid succession impinges on the recipe surface R, while the impact point by positioning of the spectacle lens L in the X and B axes and possibly the Y axis is changed according to the engraving image to be generated.

The Fig. 8 finally shows an example of a engraved by means of the machine 10 described above prescription surface R of the lens L, wherein the in Fig. 8 perpendicular to each other dashed lines do not belong to the engraving, but merely serve to explain the position of a part of the engraving. The recipe surface R shown is a progressive surface with the permanent engraving required in accordance with DIN EN ISO 8980-2, which initially has two circular markings 76, 78 spaced by 34 mm for orientation, for example, on the glass horizons passing through the glass center, the latter exactly in the middle between the two markings 76, 78 is located. Below the in Fig. 8 left mark 76 is the indication of the additional local effect 80, in the present example 2.00 diopters, while the lens L below the in Fig. 8 right mark 78 marked "R" for right. At 82 finally a manufacturer's information, engraved in the present example " ^S _L ". In addition, three lines 84 are engraved on the edge of the prescription surface R of the spectacle lens L, which indirectly characterize the centering point ZP of the spectacle lens L, which results when the in Fig. 8 lateral lines 84 are connected to a line from which a perpendicular plumb on the in Fig. 8 bottom line is like (in Fig. 8 indicated by dashed lines). This centering point ZP is later used for positioning the spectacle lens L for edge processing according to the shape of the spectacle frame.

The invention relates to a machine for processing optical workpieces, in particular plastic spectacle lenses, which has a workpiece spindle, by means of which the workpiece is rotatably drivable about a workpiece axis of rotation, and a first fast tool arrangement, by means of which a lathe chisel in FIG Direction of the workpiece and is movable away therefrom, wherein the workpiece spindle and the first fast tool assembly are also movable in a direction transverse to the workpiece axis of rotation relative to each other. In addition to and preferably in parallel to the first fast tool arrangement, a second fast tool arrangement is provided with an engraving stylus whose end facing the workpiece is substantially punctiform, the engraving stylus by means of the second fast tool assembly highly dynamic in the direction of the workpiece and away from it, so that by needling engagement of the engraving stylus with the workpiece at this in the same clamping a mark of any geometry can be generated.

LIST OF REFERENCE NUMBERS

10

machine

12

machine frame

14

editing area

16

guide rail

17

mounting surface

18

X slide

20

guide rail

21

mounting surface

22

Y carriage

23

mounting surface

24

Workpiece spindle

26

electric motor

28

milling unit

30

electric motor

32

milling spindle

34

milling tool

36

Fast tool arrangement

38

Fast tool arrangement

40

actuator

42

actuator

44

Shuttle part (shuttle)

46

Shuttle part (shuttle)

48

lathe tool

50

engraving tool

51

The End

52

cutting tips

54

cutting edge

56

mounting surface

58

spigot

60

body

62

threaded extension

64

cross hole

66

Transition surface

68

face

70

end

72

attachment section

74

top

76

mark

78

mark

80

addition power

82

manufacturer information

84

stroke

α

angle of attack

d _s

Target final thickness of the workpiece / spectacle lens

x

width direction

y

longitudinal direction

y _e

faulty axial position of the workpiece spindle

y _k

correct axial position of the workpiece spindle

z

height direction

B

Workpiece rotation axis

C

Mill turning axis

F1

Linear axis 1. Fast tool

F2

Linear axis 2. Fast tool

L

Workpiece / spectacle lens

R

prescription surface

X

Linear axis workpiece

Y

Linear axis workpiece

ZP

centration

Claims (5)

1. A machine (10) for machining optical workpieces (L), in particular plastic spectacle lenses, comprising a workpiece spindle (24), by means of which the workpiece (L) can be rotatably driven about a workpiece rotation axis (B), and a first fast-tool assembly (36), by means of which a turning tool (48) is movable in the direction of the workpiece (L) and away from it, wherein the workpiece spindle (24) and the first fast-tool assembly (36) are, in addition, movable relative to each other in a direction transverse to the workpiece rotation axis (B), characterized in that, provided adjacent to and preferably in parallel configuration with the first fast-tool assembly (36) is a second fast-tool assembly (38) with a graver (50), which has a point (74) tapering conically towards its end (51) facing the workpiece (L), so that the end (51) that faces the workpiece (L) is essentially punctiform, wherein the graver (50) is movable high-dynamically, by means of the second fast-tool assembly (38), in the direction of the workpiece (L) and away from it, so that, through needling engagement of the graver (50) with the workpiece (L), a marking (76, 78, 80, 82, 84) can be produced on the latter.
2. A machine (10) according to claim 1, characterized in that the graver (50) is movable by means of the second fast-tool assembly (38) in a fast-tool movement plane (X-F2 plane), whilst the workpiece spindle (24) and the second fast-tool assembly (38) are movable relative to one another in a plane (X-Y plane) that contains the workpiece rotation axis (B), wherein the fast-tool movement plane (X-F2 plane) is positioned obliquely (setting angle α) relative to the plane (X-Y plane) containing the workpiece rotation axis (B).
3. A machine (10) according to claim 2, characterized in that the fast-tool movement plane (X-F2 plane) and the plane (X-Y plane) containing the workpiece rotation axis (B) enclose a setting angle (α) which lies between 2° and 10°.
4. A machine (10) according to any one of the preceding claims, characterized in that the graver (50) can be advanced with positioning control (F2 axis) in the axial direction by means of the second fast-tool assembly (38).
5. A machine (10) according to any one of the preceding claims, characterized in that the point (74) forming the end (51) of the graver (50) facing the workpiece (L) comprises carbide metal.

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