EP0868972B1 - Method and apparatus for machining optical lenses - Google Patents

Description

The present invention relates to a method for processing optical Lenses and according to an apparatus for performing the method the preambles of claim 1 and claims 6 and 14 respectively.

In the manufacture of lenses, conventionally, hot-pressed glass blanks are processed, which is the shape of flat cylindrical disks or equivalent of the desired lens shape each have curved surfaces on the end faces. First, the glass blanks are grinded to the desired one Contour brought by the lens blank on a first device roughly ground on one side and a polishable one in a second step Fine grinding is generated. The lens is then removed from this first grinding machine, turned and with a second grinding machine the other side of the Coarse and fine grinding lens also provided. On a third device the lens is then polished on both sides. Finally the finish polished Lens on a fourth device, the so-called centering machine, also machined on the edge. The lens edge gets a precise, circular geometry, if necessary also with chamfers on the edges to make the edges more impact-resistant. During the centering process, the lens is made of metal between centering bells held, which align the lens so that its optical axis with the Axis of rotation of the centering spindle coincides. With unfavorable lens shapes the self-centering effect of the centering bells is not given. Then the lenses must be in a separate centering device using a light beam be centered before gluing them onto a centering spindle, using this in Offset and grinds at the outer edge to achieve that the optical Axis of the lens aligned with its geometric axis becomes.

A disadvantage of the previous method for producing lenses is that in addition to the polishing machine a total of two grinding machines and one centering machine are needed. As far as is known, this is e.g. Most modern at the moment Technology, where it has already been assumed that rough and fine grinding per lens side is performed on a single device. Yet the machine effort is considerable.

Another disadvantage is that the polished lenses in the centering machine with metallic tools, d. H. the mentioned centering bells their sensitive polished surface can be stretched, which is very light can be damaged.

In addition, it is also unfavorable that the lens in the previous method is stretched on its outer circumference, which only the quality and accuracy of a glass compact. When the first side of the lens is finished, the Lens turned as described and clamped again in a second device. With this reclamping and centering on the still not very precise Circumference of the lens can lead to undesirable inaccuracies and differences come between the optical axes of the two lens sides.

An important aim of the invention is to manufacture lenses and inexpensively at the same time to increase the machining accuracy. The proposed procedure and the device for carrying out the method further purposes a simplification of the coarse and fine grinding of both lens sides and the Centering.

Main features of the invention are set out in claims 1, 6 and 14. Embodiments of the method are the subject of claims 2 to 5. Specializations the device are listed in subclaims 7 to 13.

In a method for processing optical lenses, wherein a blank is a Lens body clamped and grind by means of coarse and fine tools and polishing is brought to a predetermined contour, the invention provides according to the characterizing part of claim 1, that the or each lens body has a heel or is provided with one that Allows one-time clamping and removed at the end of processing becomes. One therefore assumes a new geometry of the lens blank, the is usually a hot pressed vitreous body, the shape of which is within certain limits can be varied without incurring any significant additional costs. The new shape of the lens body differs from the previous shape of the Lens blanks by a clamping heel of z. B. a few millimeters in height one side of the lens body, compared to the outer diameter of the Clamping shoulder with its diameter clearly decreases.

This basic requirement permits the conduct of the procedure after which the rough and fine machining of the lens body in one and the same The clamping shoulder is clamped on one side, whereupon the lens body is turned and the back processing in turn in a single clamping takes place. During these operations, the optical axis of the The lens and its geometrical axis are precisely together because they are in a single clamping is worked. A later centering of the lens with a special one Centering machine is omitted, since the lens is already centered when it reaches the first processing stage has left.

In the first clamping there is one for the subsequent one Centering serving circumferential machining instead, so that in the second clamping of the lens body already on the machine, thus clamped very precise outer circumference and on the Turning ash of the workpiece spindle is aligned. So achieved one that during the subsequent rough and fine grinding the second Lens side the optical axis of this lens surface is more exact coincides with its geometric axis.

The embodiment according to claim 2 is very advantageous, the removal from a first clamping and the introduction into a second clamping with a only intermediate stopping and turning process takes place. This allows not only considerable savings on machine tools, but also contributes also contribute significantly to the accuracy of lens processing. It can be done in everyone Clamping according to claim 3 also the edge processing of the lens body be made.

What is important is the embodiment of claim 4, according to which the controlled movements of workpiece and tools on a single machine be that the lens body on each side first on the face and then worked on the scope. According to claim 5, the partially or fully machined Provide the lens body with a bevel at least on one side to protect the or each edge of the lens body.

a) an einem Maschinenständer sind motorische Antriebe und Führungsmittel für zwei vertikal verfahrbare Werkstückspindeln für einen darin zur Bearbeitung einspannbaren Rohling eines Linsenkörpers vorhanden,

b) den Werkstückspindeln sind zwei horizontal (in X-Achsenrichtung) verfahrbare und quer dazu um eine horizontale Achse schwenkbare Werkzeugspindeln in veränderlicher Gegenüberstellung zugeordnet,

c) zwischen den Werkzeugspindeln befindet sich eine senkrecht zur Schwenkachse verfahrbare Entladeeinrichtung,

d) der Entladeeinrichtung ist eine Ladeeinrichtung zugeordnet, die um eine weitere Schwenkachse schwenkbar ist,

(e) die Werkzeugspindeln (4; 5) weisen ein Grob- und ein Feinschliefwerkzeug (8; 9) mit je einer stirnseitigen Schleiffläche (16 bzw 19) und einer umfangseitigen Schleiffläche (17 bzw. 20) auf.

The inventive device for processing optical lenses is characterized by the following features:

a) on a machine stand there are motor drives and guide means for two vertically movable workpiece spindles for a blank of a lens body which can be clamped therein for processing,

b) the workpiece spindles are assigned two tool spindles which can be moved horizontally (in the X-axis direction) and can be swiveled transversely about a horizontal axis, in a variable comparison,

c) between the tool spindles there is a discharge device that can be moved perpendicular to the swivel axis,

d) the unloading device is assigned a loading device which can be pivoted about a further pivot axis,

(e) the tool spindles (4; 5) have a coarse and a fine grinding tool (8; 9) each with an end grinding surface (16 or 19) and a circumferential grinding surface (17 or 20).

It can be seen that a device designed in this way enables overall processing, so that for the coarse and fine grinding of both lens sides as well as the centering and the beveling only this single machine is needed. It is appropriately constructed according to claim 7 so that the pivot axes run parallel to one another and transverse to the X-axis direction. That allows one very compact construction.

According to claim 8, the workpiece spindles have clamping means for the lens body on, especially collets that can be operated pneumatically or hydraulically could be. The same applies to claim 9, according to which the unloading device and the charging device each have clamping means for the lens body, especially suction clamps. These allow gentle detection of the lens body so that the sensitive lens surface during reloading remains protected.

According to claim 10, the workpiece spindles are on the one hand and the tool spindles on the other hand, independently of each other in the direction of the Z axis or X-axis movable, with the tool spindles each having their own B-axis feature. With this design, all four spindles are used at the same time, to process two lenses at the same time.

Alternatively, the invention provides according to claim 11 that the workpiece spindles parallel to each other and perpendicular to the main extent of a feed carriage are supported on this. This enables the joint movement and therefore a drive saving. Analogously, according to claim 12, the tool spindles on a feed carriage located above the workpiece spindles be supported, which is pivotable about the horizontal pivot axis and the carries both tool spindles at a constant distance. According to the claim 13 be the same as between the workpiece spindles.

The tools each have a front and a peripheral grinding surface (feature e ). This makes it possible to produce the lens contour with one and the same tool, to machine the outer circumference in subsequent work steps and - if desired - also to create a chamfer as edge protection.

a) an einem Maschinenständer sind motorische Antriebe und Führungsmittel für einen Vorschubschlitten und für einen Vorschubwagen vorhanden,

b) der Vorschubschlitten ist vertikal (in Z-Achsenrichtung) verfahrbar und haltert zwei Werkstückspindeln, die jeweils ein Spannwerkzeug für einen darin aufnehmbaren Linsen-Rohling tragen,

c) der Vorschubwagen ist horizontal (in X-Achsenrichtung) verfahrbar sowie um eine quer zu seiner Hauptausdehnung verlaufende Achse schwenkbar und haltert zwei Werkzeugspindeln,

d) der Vorschubwagen haltert eine senkrecht zu seiner Hauptausdehnung verfahrbare Entladeeinrichtung,

e) zwischen der Entladeeinrichtung und dem Vorschubschlitten ist eine Ladeeinrichtung angeordnet, die um eine horizontale Achse schwenkbar ist,

f) die Werkzeugspindeln weisen ein Grob- und ein Feinschleifwerkzeug mit je einer stirnseitigen Schleiffläche und einer umfangsseitigen Schleiffläche auf.

The combination of claim 14, which has the following features, is particularly advantageous:

a) on a machine stand there are motor drives and guide means for a feed slide and for a feed carriage,

b) the feed slide can be moved vertically (in the Z-axis direction) and holds two workpiece spindles, each of which carries a clamping tool for a lens blank which can be accommodated therein,

c) the feed carriage can be moved horizontally (in the X-axis direction) and swiveled about an axis running transversely to its main extent and holds two tool spindles,

d) the feed carriage holds an unloading device which can be moved perpendicular to its main extent,

e) a loading device is arranged between the unloading device and the feed carriage, which is pivotable about a horizontal axis,

f) the tool spindles have a rough and a fine grinding tool, each with an end grinding surface and a peripheral grinding surface.

Such a device can be designed as a fully automatic machine, so that no manual intervention is required to process the Lens body from the blank shape to the finished contour. Essentials Quality advantages result from the fact that the optical axes of both Lens sides coincide with the geometric axis, so that the optical axes of both lens sides inevitably coincide with each other.

Further features, details and advantages of the invention result from the Wording of the claims and from the following description of an embodiment based on the drawing. This shows in 12 schematic side views the arrangement and use of the device according to the invention, which also exemplifies the sequence of the method according to the invention is illustrated.

In the device shown, two workpiece spindles 1 and 2 are on one common feed carriage 3 attached, the simultaneous movement of the both workpiece spindles 1 and 2 in the vertical direction (Z axis). In a corresponding manner, two tool spindles 4 and 5 are preferably on one common feed carriage 6 attached, the simultaneous horizontal movement (Direction X axis). For the feed carriage 6 and the associated tool spindles 4 and 5 is a common B axis to which the feed carriage 6 together with the tool spindles 4 and 5 can be pivoted in both directions.

In the case of a modified device, but not described in more detail here, it is also possible that the workpiece spindles 1 and 2 of separate feed devices be guided, which allows you to move them independently towards each other the Z axis can move. The same applies to tool spindles 4 and 5, which are also guided by separate feed devices and thereby can be moved independently of one another in the direction of the X axis. Even those for X-axis vertical B-axis can be used for tool spindle 4 and tool spindle 5 can be provided separately to each of these spindles for themselves to be able to swivel a B axis.

In the design shown, the workpiece spindles 1 and 2 are for receiving a lens body 7 arranged vertically in the lower part of the device, while in its upper part a right tool spindle 4 is a rough grinding tool 8 and a left tool spindle 5 carries a fine grinding tool 9. The grinding process itself is first carried out with the rough grinding tool 8, the according to the invention not only via an end grinding surface 16 for manufacturing the desired lens shape, but also has a peripheral Grinding surface 17, which is used to edit the lens circumference and to manufacture a chamfer serves to be able to center the lens body 7 exactly. That afterwards The fine grinding tool 9 also has an end face Grinding surface 19 and a circumferential grinding surface 20.

In addition to the two feed devices mentioned, namely feed slides 3 for moving in the direction of the Z axis and feed carriage 6 for Moving in the direction of the X axis, there is an unloading device 10 which also performs vertical movements and at their lower end over one Suction clamp 11 has. The unloading device 10 is on the feed carriage 6 attached and can therefore also horizontal movements along the X-axis To run. With the discharge device 10, the lens body 7 can be completed the first surface and after centering from the clamping tool Remove 12 from the first workpiece spindle 1.

A loading device 13, which is provided with a suction clamp 14 and in a horizontal C-axis can be rotated by 180 °, takes over on one side and on Scope machined lens body 7 from the unloading device 10. It is then into e.g. Clamping tool 15 of the second workpiece spindle designed as a collet 2 inserted and stretched on the machined edge. The unloading device 10 and the charger 13 are designed so that they from the Working area of workpiece spindles 1 and 2 or tool spindles 4 and 5 can drive out.

Fig. 1: Der Rohling des Linsenkörpers 7 wird in das Spannwerkzeug 12 der Werkstückspindel 1 eingelegt und an seinem Spannabsatz 18 mechanisch mittels des automatisch betätigbaren Spannwerkzeugs 12 gespannt, das eine vakuumunterstützte Spannzange sein kann.

Fig. 2: Mit dem Grobschleifwerkzeug 8 an der Werkzeugspindel 4 wird der Linsenkörper 7 grob vorgeschliffen, wobei die stirnseitige Schleiffläche 16 im Einsatz ist. Die vorher nötige Positionierbewegung des Grobschleifwerkzeugs 8 wird längs der X-Achse mit Werkzeugspindel 4 und Vorschubwagen 6 ausgeführt, während die Zustellbewegung durch den Vorschubschlitten 3 mit Werkstückspindel 1 sowie Spannwerkzeug 12 mit Linsenkörper 7 längs der Z-Achse erfolgt. Entsprechend dem gewünschten Arbeitsergebnis wird der Vorschubwagen 6 samt den damit verbundenen Teilen um die B-Achse geschwenkt. Während des Schleifvorgangs wird der Linsenkörper 7 mittels der Werkstückspindel 1 in Drehung versetzt, während das Grobschleifwerkzeug 8 von der Werkstückspindel 4 angetrieben wird.

Fig. 3: Nach dem Grobschleifen fährt die Werkstückspindel 1 längs der Z-Achse wieder nach unten; die Werkzeugspindel 5 mit dem Feinschleifwerkzeug 9 wird in Richtung der X-Achse in die Arbeitsposition gefahren. Der Feinschleifvorgang läuft dann ab wie vorstehend beim Grobschleifen beschrieben, wobei die stirnseitige Schleiffläche 19 im Einsatz ist. Der Vorschubwagen 6 mit den daran befestigten Werkzeugspindeln 4 und 5 wird wieder um die B-Achse geschwenkt, diesmal jedoch in Gegenrichtung.

Fig. 4: Durch Bewegen in Richtung der Z- und X-Achse werden anschließend entweder das Grobschleifwerkzeug 8 oder das Feinschleifwerkzeug 9 oder auch beide - ggf. nacheinander - in Arbeitsposition gebracht, um den Umfang des Linsenkörpers 7 zu bearbeiten. In der dargestellten Phase ist die umfangseitige Schleiffläche 20 von Feinschleifwerkzeug 9 im Einsatz. Ein Umspannen des Linsenkörpers 7 findet nicht statt, so daß die optische Achse und die geometrische Achse, die jetzt festgelegt wird, genau miteinander übereinstimmen.

Fig. 5: In einem weiteren Arbeitsschritt bringt man an dem Linsenkörper 7 eine Fase an, wozu die Werkzeugspindel 5 in erforderlicher Weise um die B-Achse geschwenkt wird. Im Einsatz ist die umfangseitige Schleiffläche 20 von Feinschleifwerkzeug 9.

Fig. 6: Durch Bewegung des Vorschubwagens 6 in Richtung der X-Achse wird die Entladeeinrichtung 10 über die Werkstückspindel 1 mit dem Linsenkörper 7 positioniert, so daß der Saugspanner 11 letztere erfassen und durch Vertikalhub aus dem Spannwerkzeug 12 der Werkstückspindel 1 entnehmen kann.

Fig. 7: Die Ladeeinrichtung 13 wird nach vorne in Arbeitsposition gefahren und führt dabei eine 180°-Drehung um die C-Achse aus, so daß der Saugspanner 14 nach oben zeigt. Er übernimmt nach dem Positionieren des Vorschubwagens 6 samt vertikal bewegter Entladeeinrichtung 10 von dieser den Linsenkörper 7.

Fig. 8: Nachdem die Entladeeinrichtung 10 hochgefahren ist, dreht sich die Ladeeinrichtung 13 nun 180° um die C-Achse, so daß der Saugspanner 14 mit dem von ihm gehaltenen Linsenkörper 7 nach unten weist.

Fig. 9: Nach Positionierung des Vorschubwagens 6 entlang der X-Achse und des Vorschubschlittens 3 in Richtung der Z-Achse kann der Linsenkörper 7 in das Spannwerkzeug 15 der Spindel 2 eingebracht werden. Die bereits bearbeitete Fläche zeigt nach unten, d. h. Richtung zur Spindel 2, während die unbearbeitete Seite mit dem Spannabsatz 18 nach oben gerichtet ist.

Fig. 10: Die zweite Seite des Linsenkörpers 7 wird durch Schleifen mit dem Grobschleifwerkzeug 8 bearbeitet, wobei die stirnseitige Schleiffläche 16 im Einsatz ist. Die Arbeitsbewegungen der verschiedenen Maschinenteile in der X- und Z-Achse sowie um die B-Achse verlaufen analog zu den vorbeschriebenen Bewegungen, d.h. wie bei der Bearbeitung der ersten Linsenseite. In diesem Arbeitsgang wird auch der Spannabsatz 18 mit abgeschliffen.

Fig. 11: Durch Schleifen mit dem Feinschleifwerkzeug 9 wird die polierfähige Oberfläche auch der zweiten Linsenseite hergestellt, wozu die stirnseitige Schleiffläche 19 eingesetzt wird.

Fig. 12: Zum Abschluß wird auch an dieser zweiten Seite der Linse 7 mittels Feinschleifwerkzeug 9 eine Fase angebracht, wobei die umfangseitige Schleiffläche 20 im Einsatz ist.

The workflow is explained below with reference to FIGS. 1 to 12.

Fig. 1: The blank of the lens body 7 is inserted into the clamping tool 12 of the workpiece spindle 1 and mechanically clamped on its clamping shoulder 18 by means of the automatically actuated clamping tool 12, which can be a vacuum-assisted collet.

Fig. 2: With the coarse grinding tool 8 on the tool spindle 4, the lens body 7 is roughly pre-ground, the end-face grinding surface 16 being in use. The previously required positioning movement of the rough grinding tool 8 is carried out along the X axis with tool spindle 4 and feed carriage 6, while the feed movement takes place through the feed slide 3 with workpiece spindle 1 and clamping tool 12 with lens body 7 along the Z axis. In accordance with the desired work result, the feed carriage 6 together with the parts connected to it is pivoted about the B axis. During the grinding process, the lens body 7 is set in rotation by means of the workpiece spindle 1, while the coarse grinding tool 8 is driven by the workpiece spindle 4.

Fig. 3: After rough grinding, the workpiece spindle 1 moves down again along the Z axis; the tool spindle 5 with the fine grinding tool 9 is moved into the working position in the direction of the X axis. The fine grinding process then proceeds as described above for rough grinding, with the front grinding surface 19 being in use. The feed carriage 6 with the tool spindles 4 and 5 attached to it is pivoted again about the B axis, but this time in the opposite direction.

Fig. 4: By moving in the direction of the Z and X axes, either the rough grinding tool 8 or the fine grinding tool 9 or both - if necessary one after the other - are then brought into the working position in order to machine the circumference of the lens body 7. In the phase shown, the circumferential grinding surface 20 of fine grinding tool 9 is in use. A reclamping of the lens body 7 does not take place, so that the optical axis and the geometric axis, which is now defined, coincide exactly with one another.

Fig. 5: In a further step, a chamfer is attached to the lens body 7, for which purpose the tool spindle 5 is pivoted about the B axis in the required manner. The peripheral grinding surface 20 of fine grinding tool 9 is in use.

Fig. 6: By moving the feed carriage 6 in the direction of the X-axis, the unloading device 10 is positioned over the workpiece spindle 1 with the lens body 7, so that the suction clamp 11 can grasp the latter and remove it from the clamping tool 12 of the workpiece spindle 1 by vertical stroke.

Fig. 7: The loading device 13 is moved forward into the working position and thereby makes a 180 ° rotation about the C-axis, so that the suction clamp 14 points upwards. After positioning the feed carriage 6 together with the vertically moving unloading device 10, it takes over the lens body 7 from the latter.

Fig. 8: After the unloading device 10 has been raised, the loading device 13 now rotates 180 ° about the C-axis, so that the suction clamp 14 with the lens body 7 held by it points downward.

9: After positioning the feed carriage 6 along the X axis and the feed carriage 3 in the direction of the Z axis, the lens body 7 can be inserted into the clamping tool 15 of the spindle 2. The surface that has already been worked points downwards, ie towards the spindle 2, while the unprocessed side with the clamping shoulder 18 is directed upwards.

Fig. 10: The second side of the lens body 7 is processed by grinding with the coarse grinding tool 8, the front grinding surface 16 being used. The working movements of the various machine parts in the X and Z axes and around the B axis are analogous to the movements described above, ie as when processing the first side of the lens. In this step, the clamping shoulder 18 is also ground.

11: The polishable surface of the second lens side is also produced by grinding with the fine grinding tool 9, for which purpose the front-side grinding surface 19 is used.

Fig. 12: Finally, a bevel is also attached to this second side of the lens 7 by means of a fine grinding tool 9, the peripheral surface 20 being used.

The described method in cooperation with the invention Device results in lenses of higher precision at significantly lower manufacturing costs. Instead of the usual three machines for coarse and fine grinding the first side or rough and fine grinding of the second side with subsequent Centering on a separate device is now only one device needed. Because the lens body is already centered during the grinding process the elaborate and dangerous for the sensitive lens surface Center the polished lens.

For double-sided processing of optical lenses, the ones used According to the invention, blanks of each lens body 7 have a clamping shoulder 18. A only one device is sufficient to carry out the method. She disposes of Via workpiece spindles 1, 2 and tool spindles 4, 5 with coarse tools 8 and fine tools 9 also via an unloading device 10 and a loading device 13, the successive interaction of the one Side and circumferentially machined lens body 7 from a clamping tool 12 Remove from workpiece spindle 1, turn through 180 ° and to machine the insert the other side centered in a clamping tool 15 of workpiece spindle 2. The workpiece spindles 1, 2 can be parallel to each other on a horizontal movable and height-adjustable feed carriage 3 can be attached. A Feed carriage 6 can carry the tool spindles 4, 5 together with the unloading device 10 Move together and swivel around a horizontal axis B. The charger 13 is between the workpiece spindles 1, 2 and the tool spindles 4, 5 pivotable about a horizontal axis C.

Reference list

B axis

C axis

X axis

Z axis

1, 2

Workpiece spindles

3rd

Feed carriage

4, 5

Tool spindles

6

Feed carriage

7

Lens blank

8th

Coarse grinding tool

9

Fine grinding tool

10th

Unloading device

11

Suction clamp

12th

Clamping tool

13

Loading device

14

Suction clamp

15

Clamping tool

16, 17

Grinding surfaces

18th

Heel

19, 20

Grinding surfaces

Claims (14)

1. Procedure for processing optical lenses by chucking a blank of a lens body (7) in rotatable chucking means (12) and providing it with a predefined contour through grinding and finishing by means of coarse and finishing tools, the lens body (7) being provided with or having a flat chucking extension (18) of receding diameter which extension permits single chucking for each lens side to be processed and is removed at the end of processing, coarse processing and finishing of the first side of the lens body (7) being performed unilaterally in one and the same chucked position of the chucking extension (18), the lens body circumference being processed in this first chucked position for subsequent centering, whereupon the chucked lens body is turned round (Figs. 7 and 8) and processing of the back is again performed in a single chucked position.
2. Procedure according to claim 1, wherein unloading from a first chuck and insertion into a second chuck are performed in a single stalling and inverting operation.
3. Procedure according to claim 1 or claim 2, wherein in the each chucked position, the respective edge of the lens body (7) is also processed.
4. Procedure according to claim 1, in which the workpiece and the tools are moved toward each other and away from each other in a controlled way, wherein these movements are performed in a single device and such that the lens body (7) is processed on either side first on the face and then on the circumference.
5. Procedure according to any one of claims 1 to 4, wherein a partly processed or finished lens body (7) is provided with an edge chamfer at least on one side.
6. Device for implementing the procedure according to any one of claims 1 to 5, comprising the following features:

   a) a machine column is provided with motor drives and guiding means for two vertically displaceable workpiece spindles (1; 2) for a blank of a lens body (7) to be chucked by them for processing,

   b) two tool spindles (4; 5) that are horizontally displaceable in an X-axis direction and are slewable at a right angle thereto around a horizontal slewing axis (B) are associated to the workpiece spindles (1; 2) in variable opposite arrangement,

   c) an unloading device (10) that is displaceable perpendicularly to the horizontal slewing axis (B) is arranged between the tool spindles (4; 5),

   d) a loading device (13) slewable around a further slewing axis (C) is associated to the unloading device (10),

   e) the tool spindles (4, 5) are equipped with a coarse-grinding tool (8) and a precision-grinding tool (9), each having a face grinding surface (16 and 19, respectively) and a circumferential grinding surface (17 and 20, respectively).
7. Device according to claim 6, wherein the sewing axes (B; C) are parallel to each other and at right angles to the direction of the X-axis.
8. Device according to claim 6 or claim 7, wherein the workpiece spindles (1; 2) have chucking means for the lens body (7), especially collets (12; 15).
9. Device according to any one of claims 6 to 8, wherein the unloading device (10) and the loading device (13) each have chucking means for the lens body (7), especially suction chucks (11; 14).
10. Device according to any onf of claims 6 to 9, wherein the workpiece spindles (1; 2) on the one hand and the tool spindles (4; 5) on the other hand are displaceable independently of each other in the direction of a Z-axis and of the X-axis, respectively, and wherein each of the tool spindles (4; 5) has an individual sewing axis (B).
11. Device according to any one of claims 6 to 9, wherein the workpiece spindles (1; 2) are mounted on a feed slide (3) parallel to each other and perpendicularly to the main dimension of the feed slide (3).
12. Device according to any one of claims 6 to 11, wherein the tool spindles (4; 5) are mounted on a feed carriage (6) that is located above the workpiece spindles (1; 2) and is slewable around the horizontal slewing axis (B).
13. Device according to claims 11 and 12, wherein the workpiece spindles (1; 2) and the tool spindles (4; 5) are arranged adjacent each other at equal distances.
14. Device for implementing the procedure according to any one of claims 1 to 5, comprising the combination of the following features:

    a) a machine column is provided with motor drives and guiding means for a feed slide (3) and for a feed carriage (6),

    b) the feed slide (3) is vertically displaceable in a Z-axis direction and holds two workpiece spindles (1; 2) each of which is carries a chucking tool (12 and 15, respectively) for a blank of a lens body (7) to be received by them,

    c) the feed carriage (6) is horizontally displaceable in an X-axis direction as well as slewable around a horizontal B-axis running at right angles to the main dimension of the feed carriage which supports two tool spindles (4; 5),

    d) the feed carriage (6) holds an unloading device (10) that is displaceable perpendicularly to the main feed carriage dimension,

    e) a loading device (13) that is slewable around a horizontal axis (C) is arranged between the unloading device (10) and the feed slide (3),

    f) the tool spindles (4; 5) are equipped with a coarse-grinding and a precision-grinding tool (8; 9), each having a face grinding surface (16 and 19, respectively) and a circumferential grinding surface (17 and 20, respectively).

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