Machining device, use of a cross-table and method for facing an optical workpiece

Abstract

The invention relates to a machining device for optical workpieces, to a use of a cross-table, and to a method for facing an optical workpiece, wherein the workpiece is first fed to a tool along a roller-supported feed axle and is then machined by facing only by axial movement of the tool. Furthermore, the workpiece being machined is moved along a transverse axis with hydrostatic mounting during machining. This enables a simple and cost-effective design and highly precise machining.

Description

[0001] Machining device, use of a cross table and method for face turning of an optical workpiece

[0002] The present invention relates to a machining device for face turning of an optical workpiece according to the preamble of claim 1, a use of a cross table according to the preamble of claim 19 and a method for face turning of an optical workpiece according to the preamble of claim 28.

[0003] Optical components, such as contact lenses, intraocular lines, or contact lens shapes, are machined, particularly to create individual optical properties, by face turning, i.e., by machining the flat side. Very high machining accuracy is desirable in this process.

[0004] German patent DE 102005 021 640 B4 discloses a machining device for processing optical workpieces, in particular plastic spectacle lenses. The device comprises a cross table with a workpiece spindle attached to it, as well as two Fast Tool assemblies and a milling station opposite the spindle. A workpiece is rotated by the workpiece spindle and simultaneously machined by face turning using the Fast Tool assemblies. During face turning, only one Fast Tool assembly processes the workpiece, while the other Fast Tool assembly moves in the opposite direction, thus achieving mass compensation to minimize disruptive vibrations and thereby achieve a high surface quality. However, this setup is complex and does not result in optimal surface quality.

[0005] DE 196 80 863 B4 discloses a method and a machining tool for producing optical surfaces of progressive spectacle lenses or related mold shells by face turning, wherein a rapid tool movement with a stroke of approximately 1 mm in the axial direction of a workpiece spindle is used to machine an aspherical shape. According to one embodiment, the workpiece spindle is arranged on a cross slide. The slide with the workpiece spindle is moved into a suitable position in the direction of the tool and then clamped for the duration of the machining process. To produce the spherical shape, a (further) infeed of the workpiece spindle is required, so that, considering the axis of rotation and the transverse axis, a conventional four-axis machining operation results.WO 2013 / 174487 A2 discloses a device and a method for face turning a flat side of an optical workpiece, wherein fluidic bearings are provided, in particular for a workpiece spindle and for a rotary table with a fast-tool arrangement. Accordingly, a complex setup is provided.

[0006] German patent DE 102007031 703 A1 discloses a machining device for face turning of optical workpieces, in particular plastic spectacle lenses, wherein a workpiece spindle is pivotable about a vertical pivot axis and can be moved radially to various fast-tool arrangements by means of a linear drive unit. The design is complex and does not result in optimal surface quality.

[0007] The present invention is based on the objective of providing a machining device, a use of a cross table and a method for face turning of an optical workpiece, in particular an intraocular lens, contact lens or contact lens shape, wherein a simple, cost-effective design as well as high-precision surface machining and high surface quality are enabled, particularly in the production of non-rotationally symmetrical surface geometries, and wherein, in particular, subsequent polishing can even be omitted.

[0008] The above problem is solved by a processing device according to claim 1, a use according to claim 19, or a method according to claim 28. Advantageous embodiments are the subject of the dependent claims.

[0009] A proposed machining device is characterized in particular by the fact that a cross table with a spindle for rotating the workpiece in one feed direction is mounted on roller bearings or otherwise non-fluidically supported, and is mounted or guided more precisely or fluidically, especially hydrostatically, in a transverse direction. In particular, the machining device is designed such that, during or until the completion of machining the optically effective flat side, i.e., the end face of the workpiece, the cross table is moved only transversely along the more precise, fluidic or hydrostatic mounting or guide by a fast-tool arrangement with a (primarily) axially movable or acting tool. This allows for a particularly high surface quality during face turning, while enabling a relatively simple and therefore cost-effective design.One basic idea is therefore to use the rolling-bearing axis (Z1) of the cross table only for setting the process starting position, i.e., for the (coarser) feed of the workpiece to the fast-tool arrangement or its tool.

[0010] One advantage of rolling bearings lies in their large form factor and high stiffness, as well as their low cost. However, disadvantages include the generation of undesirable signatures, i.e., medium-frequency defects and surface roughness, which arise when the position of the workpiece or tool changes during machining.

[0011] Therefore, after the process position is reached using the roller-bearing-mounted axis as a non-interpolating positioning axis, the subsequent machining process and the tool path movement (X / Z / C) for geometry generation are exclusively generated using fluidic (hydrostatic, hydrodynamic, or aerostatic) interpolating axes to achieve the highest machining quality. In particular, such a high surface quality can be achieved that subsequent polishing is no longer necessary.

[0012] During the machining process, the fluidically supported X-axis moves the tool in (at least essentially) a radial direction, and the Fast-Tool moves in (at least essentially) an axial or Z-direction.

[0013] In addition to the linear motion, the workpiece is also rotated around the axis of rotation using a fluidically supported C-axis or spindle.

[0014] In particular, it is not currently common practice to design a cross table with one hydrostatic axis of motion as having a non-fluidically supported axis or a rolling-bearing axis. This leads to significant cost reductions, while, as proposed, achieving a particularly high surface quality.

[0015] Preferably, the roller-bearing-mounted axis is fixed during flat-side machining of the workpiece not by clamping, but by adjusting its position. This minimizes or eliminates errors, thus achieving particularly high quality. The proposed machining device is especially suitable for machining optical workpieces with a maximum diameter of 51 mm, or contact lenses, contact lens shapes, and / or intraocular lenses, particularly where the optically effective flat side, i.e., the end face of the workpiece, is machined using only three machining axes that vary or interpolate for the machining process. This allows for faster and / or more precise surface finishing of such workpieces than previously possible with four machining axes, while maintaining a particularly cost-effective design of the machining device.

[0016] One proposed use of a cross table for face turning of the optical workpiece involves the cross table being linearly movable along a roller-bearing-mounted feed axis and along a fluidically-mounted or, more precisely, a transverse axis. It also holds or supports a spindle for rotating the workpiece around a rotary axis. The workpiece is initially fed to a tool of a fast-tool arrangement along the feed axis by means of the cross table. During and until the machining of the workpiece by a tool of the fast-tool arrangement is completed—that is, until the completion of the flat-side machining by the fast-tool tool—the cross table is moved only along the transverse axis, i.e., along the more precise or fluidic guide.

[0017] In particular, when processing contact lenses, it can also happen that the edge area of ​​the lens is machined as a peripheral process using the same setup as the end surface, with a second, specially positioned tool. This ensures high geometric precision between the so-called edge and the back surface of the lens, which is important for the wearing comfort of the lens in the eye.

[0018] The edge can also be designed as an undercut, i.e., one (twice approached) X-position of the toolpath has two different Z-values ​​in the edge area of ​​the lens.

[0019] A proposed method for face turning an optical workpiece involves rotating the workpiece around a rotary axis during machining. This method is characterized by the fact that the workpiece is initially fed to a fast-tool arrangement with a tool via a roller-bearing-mounted feed axis. Subsequently, the workpiece feed along the feed axis remains constant during machining; instead, the axial feed is achieved solely by moving the tool along a linear axis via the fast-tool arrangement. This approach allows for a particularly high surface quality of the machined workpiece.

[0020] The Fast-Tool arrangement preferably features a rolling-bearing-free or aerostatic or magnetic bearing or guide for the rapid linear movement of the tool along the linear axis, i.e., a bearing or guide of the linear axis that is significantly more precise compared to a rolling-bearing or feed axis.

[0021] As proposed, a particularly high surface quality of the machined surface can be achieved despite the use of relatively inexpensive rolling bearings for the (coarser) feed of the workpiece. The transverse movement of the workpiece to be machined during face turning preferably occurs along a transverse axis that is fluidically, in particular hydrostatically, supported, and therefore correspondingly precise and, in particular, also rigid, in order to enable or support the achievement of the desired high surface quality during machining.

[0022] Individual aspects and features of the present invention, both those mentioned above and those that follow, can be combined with one another as desired, but can also be implemented independently of one another.

[0023] Further aspects, features, advantages and properties of the present invention will become apparent from the claims and the following description of two preferred embodiments with reference to the drawing. It shows:

[0024] Fig. 1 shows a schematic perspective view of a proposed machining device according to a first embodiment; and

[0025] Fig. 2 shows a schematic perspective view of a proposed machining device according to a second embodiment.

[0026] The machining device 1 shown in a schematic perspective view in Fig. 1 is used for machining an optical workpiece 2 by face turning and optionally also for further machining of the workpiece 2. In face turning, an optical surface or end face 21 of the workpiece 2, which is only schematically indicated, is shaped by machining, i.e., by cutting, in order to achieve, for example, a non-rotationally symmetrical surface - also called a freeform surface - with the desired optical properties.

[0027] The workpiece 2 is in particular an intraocular lens, a contact lens, or a contact lens shape. However, it could also be any other type of optical lens.

[0028] The workpiece 2 preferably has a diameter of several millimeters or centimeters, particularly preferably a maximum of 51 mm.

[0029] The machining device 1 preferably has two linear or translational machine axes for moving the workpiece 2, namely a feed axis Z1 and a transverse axis X. The two axes X, Z1 preferably run horizontally and / or transversely or perpendicularly to each other.

[0030] The term "machine axis" here refers to an assembly that enables a driven and, in particular, controlled or regulated translational movement and includes a guide for guiding the moving parts of the machine axis.

[0031] Preferably, the feed axis Z1 is supported by the transverse axis X, as shown in Fig. 1, or vice versa. Such an arrangement or stacking of axes is also referred to as a cross slide or cross table.

[0032] The machining device 1 therefore preferably has a cross table 3 in the aforementioned sense.

[0033] Preferably the machining device 1 or the cross table 3 has a first slide 4 with a particularly fluidic bearing or guide 5, such that the first slide 4 is mounted and guided so as to be displaceable or linearly movable along the transverse axis X.

[0034] The machining device 1 or the cross table 3 preferably further comprises a drive (not shown in detail) which acts on the first slide 4 or, in particular, acts between the first slide 4 and the guide 5 in order to move and position the first slide 4 as desired along the transverse axis X.

[0035] The transverse axis X is preferably designed as a machine axis or linear axis and / or is position- or bearing-controlled.

[0036] The drive assigned to the first slide 4 is in particular designed as an electric direct drive or linear motor, especially preferably as an ironless linear motor.

[0037] Fluidic bearing is particularly preferred as hydrostatic bearing, especially with a medium-viscosity bearing oil.

[0038] The machining device 1 or the cross table 3 preferably has a second slide 6, which is mounted and guided in a displaceable or linearly movable manner along the feed axis Z1, particularly by means of a rolling bearing or rolling bearing guide 7, and especially preferably on the first slide 4.

[0039] The machining device 1 or the cross table 3 preferably has a drive (not shown in detail) for moving and positioning the second slide 6 along the feed axis Z1.

[0040] The delivery axis Z1 is preferably designed as a machine axis or linear axis and / or position- or bearing-controlled.

[0041] The drive associated with the second slide 6 is preferably designed as an electric direct drive or linear drive, in particular as a linear motor with an iron core. However, other design solutions are also possible.

[0042] The second slide 6 is particularly preferably guided movably via several rolling bearing groups, especially on top of the first slide 4.

[0043] The rolling bearing guide 7 is preferably designed as a ball bearing and is therefore cost-effective.

[0044] The transverse axis X or bearing / guide 5 preferably has a tracking accuracy or straightness better than 500 nm per 100 mm travel distance, preferably better than 250 nm per 100 mm travel distance, in particular better than 120 nm per 100 mm travel distance, especially preferably of about 100 nm per 100 mm travel distance, and / or a significantly better tracking accuracy or straightness than the feed axis Z1 or guide 7.

[0045] The machining device 1 preferably has a spindle 8 for holding and rotating the workpiece 2. In particular, the workpiece 2 can be rotated or turned about a rotary axis C by means of the spindle 8. The turning is carried out in a controlled or regulated manner with a defined rotational position.

[0046] Preferably the spindle 8 has a driven, rotating shaft 9 with a holder or chuck (not shown) for fastening or holding the workpiece 2 to be machined.

[0047] The spindle 8 or the workpiece 2 is preferably movable along the feed axis Z1 and / or transverse axis X.

[0048] The spindle 8 is preferably arranged on or at the cross table 3 or second slide 6.

[0049] Preferably, the spindle 8 or the workpiece 2 is guided movably along the feed axis Z1 by means of the rolling bearing 7 and / or guided movably along the transverse axis X by means of the fluidic bearing 5.

[0050] The spindle 8 preferably has only two (linear) axes of movement, here the feed axis Z1 and the transverse axis X.

[0051] Preferably, the workpiece 2 is machined in a blocked state. The workpiece 2 is therefore preferably provided with a temporary holder, a so-called block piece, in order to hold the workpiece 2 in a defined and very simple manner during machining.

[0052] However, machining without a block or other form of clamping, for example using a mechanical chuck or vacuum chuck, is also possible in principle when machining in the machining device 1. Optionally, the workpiece 2 is machined in the machining device 1 exclusively on one or the same end face 21 or (optical) surface, in particular the block-free side / surface.

[0053] The machining device 1 preferably has a fast-tool arrangement 10 with at least one preferably protruding tool 11, in particular a diamond-coated turning tool.

[0054] The tool 11 is preferably attached to a holder or runner 12 of the Fast-Tool arrangement 10 in a particularly interchangeable manner.

[0055] Optionally, the Fast-Tool arrangement 10 can also include an additional or second turning tool or several additional turning tools, e.g. for roughing and finishing and / or additional machining independent of face turning, as indicated by dotted lines in Fig. 2.

[0056] The machining device 1 or fast-tool arrangement is particularly preferred.

[0057] 10 according to Figs. 1 and 2 is designed and / or used in such a way that, in addition to face turning, edge machining of the workpiece 2, in particular as is usual with a contact lens, is also carried out to machine and / or produce a rounded and / or undercut edge 20 (also called edge or bevel) by the Fast-Tool arrangement 10 and in particular an additional tool, preferably positioned at an angle to the linear axis Z2 or feed axis Z1.

[0058] 11 can be performed on the Fast-Tool arrangement 10. During this edge processing using the Fast-Tool arrangement 10, the workpiece 2 is then preferably also moved along the transverse axis X or fed to the corresponding tool 11 of the Fast-Tool arrangement 10.

[0059] Using the Fast-Tool arrangement 10, the runner 12 or the tool 11 can be moved back and forth very quickly, especially with an acceleration of more than 1 g (= 9.81 m / s²). -2) or 10 g, particularly preferably several 10 g, to machine the end face of the workpiece 2 rotating by the spindle 8 and to shape the flat side or end face 21 of the workpiece 2 in the desired manner by corresponding axial movements of the tool 11. This is referred to as end turning. In particular, the tool 11 can be moved back and forth once or several times over one revolution of the workpiece 2. The Fast-Tool arrangement 10 has a drive (not shown in detail), in particular a direct drive or linear motor, to move the runner 12 and the tool 11 linearly back and forth in the desired manner along the linear axis Z2.

[0060] The linear axis Z2 is preferably designed as a machine axis or linear axis and / or position- or bearing-controlled.

[0061] The Fast-Tool arrangement 10 is particularly preferably constructed as described in WO 2013 / 117327 A2 and is in particular provided with an integrated compensating drive for moving a compensating body in opposite phase to the rotor for minimizing vibration.

[0062] The stroke of the Fast-Tool arrangement 10 or of the tool 11 is preferably at least 5 mm, preferably more than 10 or 20 mm, in particular more than 25 mm, and most preferably approximately 30 mm or more. The stroke is preferably a maximum of approximately 60 mm, in particular approximately 50 mm or less.

[0063] Preferably, the runner 12 is mounted aerostatically or magnetically and / or without rolling bearings to enable the desired high machining accuracy. The runner 12 is therefore mounted or guided more precisely than the feed axis Z1.

[0064] The linear axis Z2 preferably has a tracking accuracy or straightness better than 500 nm per 100 mm travel, preferably better than 250 nm per 100 mm travel, in particular better than 120 nm per 100 mm travel, especially preferably of about 100 nm per 100 mm travel, and / or a significantly better tracking accuracy or straightness than the feed axis Z1 or guide 7.

[0065] The linear axis Z2 is in particular a machine axis in the above sense.

[0066] The motion axes Z1 and transverse axis X of the spindle 8, the rotary axis C and the motion axis Z2 of the fast-tool arrangement 10 are in particular (position-)controlled axes or CNC axes. The linear axis Z2 of the tool 11 preferably runs at least substantially in the axial direction of the spindle 8 or in the direction of the feed axis Z1.

[0067] The spindle 8 is movable in the horizontal direction, or X-direction, transversely to the tool 11 opposite it during the rotary (machining) operation, so that the tool 11 can move across the entire end face 21 of the workpiece 2 as it rotates. It is important that the tool 11 (with its cutting edge) moves precisely over the center of the workpiece 2, or through the axis of rotation C, and not laterally past it. For this purpose, the linear axis Z2 of the Fast-Tool arrangement 10 is preferably inclined slightly to the plane of motion defined by the axes Z1 and X, by the angle W, as schematically indicated. This enables height adjustment as defined in DE 10 2005 021 640 B4.

[0068] In the illustrated example, the axes of movement Z1 and X preferably run horizontally. Accordingly, the movement axis Z2, which runs at least substantially horizontally, is inclined slightly to the horizontal and / or in the vertical plane in order to produce a component perpendicular to the feed axis Z1 or the Z1-X plane, i.e., in the Y direction, when the tool 11 moves along the linear axis Z2. Thus, by varying the feed position of the workpiece 2 along the feed axis Z1, the height or position in the Y direction of the tool 11 impacting the workpiece 2 can be varied.

[0069] The inclination of the linear axis Z2 is relative to the feed axis Z1 or the plane of the axes Z1 and X or to the horizontal.

[0070] The angle W is preferably a maximum of 12 degrees or less, in particular about 3 to 9 degrees.

[0071] The inclination of the linear axis Z2 or fast-tool arrangement 10 is preferably selected such that it rises towards the cross table 3, the spindle 8, or the workpiece 2. This has the advantage that, in the event of a power failure, the electric drive of the fast-tool arrangement 10 no longer holds the tool 11 in a working position that may be advanced towards the workpiece 2, but rather the runner 12 with the tool 11 moves or retracts into a retracted position due to the force of gravity, to the right in Figure 1. The machining device 1 preferably has a frame or machine bed 13.

[0072] The machining device 1 or the machine bed 13 preferably has a bearing surface 14 for the cross table 3 or the fluidic bearing 5.

[0073] The machining device 1 or the machine bed 13 preferably has a particularly raised bearing surface 15 for the Fast-Tool arrangement 10.

[0074] The bearing surface 15 is preferably raised above the bearing surface 14 in order to enable the Fast-Tool arrangement 10 to be mounted on the machine bed 13 with as little vibration as possible or directly.

[0075] The bearing surface 15 is preferably inclined, at least in the area of ​​the fast-tool arrangement 10, according to the inclination of the linear axis Z2.

[0076] In the illustrated example, the machine bed 13 for the cross table 3 on the one hand and the fast tool arrangement 10 on the other hand are preferably formed in one piece.

[0077] The machining device 1 preferably has at least one additional machining unit, in the example shown the additional machining unit 16 and / or the additional machining unit 18.

[0078] The additional machining device 16 is equipped, in particular, with a rotatably driven milling cutter or drill 17, in order to be able to machine the workpiece 2 differently, e.g., after the desired flat-side machining by face turning. The machining device 16 thus forms an additional machining station, in particular next to the Fast-Tool arrangement 10 and / or on the bearing surface 15 of the machine bed 13.

[0079] The additional machining unit 18 includes, for example, a machining tool 19 for further machining of the workpiece 2, for example, for edge machining. The additional machining unit 18 also forms an additional machining station and is preferably arranged next to the fast-tool arrangement 10 and / or on the bearing surface 15 of the machine bed 13. Preferably, the fast-tool arrangement 10 is arranged between the additional machining units 16, 18 or machining stations.

[0080] The additional machining stations can be used to machine the workpiece 2 before and / or after face turning, e.g. rough pre-machining, edge machining, diameter adjustment, milling, drilling or the like.

[0081] The tools 17, 19 of the further machining devices 16,18 or machining stations can optionally be fixed and / or movable or rotating or driven.

[0082] The further machining devices 16, 18 or machining stations can be approached as required, in particular by lateral adjustment along the transverse axis X, from the cross table 3 or from the spindle 8 or the workpiece 2, wherein the workpiece 2 is then preferably moved along the feed axis Z1 and machined as desired. In particular, the movement along the feed axis Z1 can also be used for the additional machining operations.

[0083] The slightly lower accuracy of the feed axis Z1 can be accepted for the additional machining operations at the additional machining stations, since these operations preferably do not shape the optical front face or significantly determine the optical properties of the workpiece 2.

[0084] Preferably, the tracking accuracy or straightness of the transverse axis X or bearing / guide 5 and / or the linear axis Z2 or fast-tool arrangement 10 is significantly better, in particular by at least a factor of 2, than the tracking accuracy or straightness of the feed axis Z1 or guide 7. Accordingly, the transverse axis X or bearing / guide 5 and / or the linear axis Z2 or fast-tool arrangement 10 are (significantly) more accurate, in particular by at least a factor of 2, than the feed axis Z1 or its guide 7.

[0085] Fig. 2 shows a second embodiment of the proposed machining device 1. Only the differences will be discussed in detail below, so that the previous explanations apply accordingly or additionally. The shaft 9 of the spindle 8 is axially adjustable and positionable. In particular, the shaft 9 or its bearing or drive unit is axially displaceable via the bearing / guide 7, preferably by ball bearing, as only schematically indicated in Fig. 2, and axially positionable via a drive (not shown), in particular a direct drive or linear motor. Preferably, the quill, i.e., rotary drive, rotary bearing, and shaft 9, is mounted as a unit axially displaceable from the bearing 7 or along the feed axis Z1 in a housing of the spindle 8. Fig. 2 shows a forward position in which the workpiece 2 is already positioned towards the tool 11.

[0086] The spindle 8 is preferably designed as a quill and / or forms a machine axis or the feed axis Z1.

[0087] In particular, in the second embodiment, the first slide 4 and the spindle 8 form the cross table 3.

[0088] The spindle 8 is preferably mounted directly or rigidly on the first slide 4. In particular, the second slide 6 of the first embodiment can therefore be omitted.

[0089] It should be noted that the proposed machining devices 1 are particularly preferred for machining, especially face turning, an optical workpiece 2, such as an intraocular lens, contact lens or contact lens mold, or other shape for an optical component. However, the machining devices 1 can also be used for eyeglasses, various types of shapes, other components requiring a high optical surface finish (e.g., watch parts), conventional electro-optics, and crystalline and non-crystalline optical components. The diameter of the workpiece 2 to be machined, or the flat surface to be machined (i.e., face 21), is preferably a maximum of 51 mm.

[0090] As proposed, the machining device 1 or the cross table 3, according to both embodiments, is used in such a way that the workpiece 2 to be machined is first fed along the feed axis Z1 to the fast-tool arrangement 10 or its tool 11. This feed is thus carried out along the rolling bearing 7 or by means of the second slide 6 in the first embodiment and by means of the spindle (quill) 7 in the second embodiment. Preferably, this feed position is maintained throughout the entire machining process or until the machining of the flat side 21 of the workpiece 2 is completed by face turning or by the fast-tool arrangement 10 – in particular by adjusting the position and not by clamping – i.e., during or for machining by the workpiece 11, only the tool 11 is moved from the fast-tool arrangement 10 along the linear axis Z2 (especially since this is more precise than the feed axis Z1).Simultaneously, a movement can also take place along the transverse axis X, i.e. along the more precise fluidic or hydrostatic bearing 5 compared to the rolling bearing guide 7, or by means of the cross table 3 or first slide 4.

[0091] As proposed, the feed position of the feed axis Z1 or rolling bearing for machining the entire end face 21 or at least substantially the entire surface of the end face 21 is maintained by the same tool 11, preferably by controlling the position and not by clamping, in order to avoid or minimize machining errors and to achieve particularly high surface qualities or machining qualities.

[0092] The machining is preferably carried out at relatively high rotational speeds of the workpiece 2 or the rotary axis C of, in particular, more than 100 revolutions per minute, especially preferably more than 300 revolutions per minute in the area of ​​the workpiece center and / or of a maximum of 25000 revolutions per minute, preferably less than 10000 revolutions per minute, in particular less than 6000 revolutions per minute, and at correspondingly high movement frequencies of the tool 11 along the linear axis Z2.

[0093] The (shaping or machining) processing of the flat or end face 21 of the workpiece 2 is particularly preferably carried out exclusively by three interpolating axes of motion or machine axes of the machining device 1, i.e., here only by means of the rotary axis C, the transverse axis X, and the linear axis Z2. Particularly preferably, the feed axis Z1 is kept constant or fixed during machining or for machining the entire optically relevant surface of the flat face 21 with the same tool 11 – particularly preferably by exclusively controlling the position of the feed axis Z1 to a constant target or actual value. This enables high-precision machining of the workpiece 2, whereby workpiece accuracies or surface accuracies or form errors of a maximum of 100 nm can be achieved.In particular, such high surface qualities are achieved with the surface produced solely by face turning – i.e., such high surface finishes and dimensional accuracies – that subsequent polishing is not required or does not take place.

[0094] The proposed machining and the proposed use of a cross table 3 with different bearings for the feed axis Z1 on the one hand and the transverse axis X on the other hand, allows for such a machining quality that, in particular, a contact lens shape or other shapes for an optical lens can be produced according to or by means of the proposed machining device 1.

[0095] Ideally, for edge machining of the workpiece 2 using the Fast-Tool arrangement 10, the same feed position along the feed axis Z1 can be maintained as for machining the end face 21, in particular an inner side of the contact lens. This may also depend on the positioning of the tools 11 on the Fast-Tool arrangement 10 and / or the stroke of the Fast-Tool arrangement 10.

[0096] The running accuracy or straightness of the bearing or guide 7 or of the transverse axis X and / or the linear axis Z2 is preferably better than 500 nm per 100 mm travel distance, preferably better than 250 nm per 100 mm travel distance, particularly in the range of about 120 or 100 nm per 100 mm travel distance, and is accordingly conducive to the desired high-precision machining.

[0097] A fluidic bearing or guide can generally, preferably optionally, be designed as a hydrostatic, aerostatic or magnetic bearing or guide.

[0098] One basic idea is therefore to use the rolling-bearing axis (Z1) of the cross table only for setting the process starting position, i.e., for the (coarser) feed of the workpiece to the fast-tool arrangement or its tool.

[0099] One advantage of rolling bearings lies in their large form factor and high stiffness, as well as their low cost. However, disadvantages include the generation of undesirable signatures, i.e., medium-frequency defects and surface roughness, which arise when the position of the workpiece or tool changes during machining.

[0100] Therefore, after the process position is reached using the roller-bearing-mounted axis as a non-interpolating positioning axis, the subsequent machining process and the tool path movement (X / Z / C) for geometry generation are exclusively generated using fluidic (hydrostatic, hydrodynamic, or aerostatic) interpolating axes to achieve the highest machining quality. In particular, such a high surface quality can be achieved that subsequent polishing is no longer necessary.

[0101] During the machining process, the fluidically supported X-axis moves the tool in (at least essentially) a radial direction, and the Fast-Tool moves in (at least essentially) an axial or Z-direction.

[0102] In addition to the linear motion, the workpiece is also rotated around the axis of rotation using a fluidically supported C-axis or spindle.

[0103] In particular, when processing contact lenses, it can also happen that the edge area of ​​the lens is machined as a peripheral process using the same setup as the end surface, with a second, specially positioned tool. This ensures high geometric precision between the so-called edge and the back surface of the lens, which is important for the wearing comfort of the lens in the eye.

[0104] The edge can also be designed as an undercut, i.e., one (twice approached) X-position of the toolpath has two different Z-values ​​in the edge area of ​​the lens.

[0105] Reference symbol list:

[0106] 1 processing device

[0107] 2 workpieces

[0108] 3 Cross table

[0109] 4 first sled

[0110] 5 fluidic storage

[0111] 6 second sled

[0112] 7 Rolling bearing

[0113] 8 spindles

[0114] 9th wave

[0115] 10 Fast Tool Arrangement

[0116] 11 tools

[0117] 12 runners

[0118] 13 Machine bed

[0119] 14 Storage area (for cross table)

[0120] 15 Storage area (for Fast-Tool arrangement)

[0121] 16 additional processing units

[0122] 17 milling cutters / drill bits

[0123] 18 additional processing units

[0124] 19 Machining tool 20 Edge 21 Flat side

[0125] W angle X transverse axis Y vertical axis

[0126] Z1 Delivery axis Z2 Linear axis

Claims

Patent claims:

1. Machining device (1 ) for face turning of an optical workpiece (2), in particular an intraocular lens, contact lens or contact lens shape, comprising a cross table (3), a spindle (8) for rotating the workpiece (2) about a rotary axis (C), and a fast-tool arrangement (10) for linear movement of a tool (11 ) along a linear axis (Z2), wherein the spindle (8) is arranged on the cross table (3) for linear movement along a feed axis (Z1 ) and along a transverse axis (X) extending transversely thereto, wherein the workpiece (9) can be moved to the tool (11 ) by means of the cross table (3) along the feed axis (Z1 ), characterized in that the cross table (3) is mounted on roller bearings or otherwise non-fluidically supported in the feed axis (Z1) and that the cross table (3) is mounted fluidically or more precisely in the transverse axis (X).

2. Machining device according to claim 1, characterized in that the Fast-Tool arrangement (10) is stationary, in particular fixed on a frame or machine bed (13) of the machining device (1).

3. Machining device according to claim 1 or 2, characterized in that the Fast-Tool arrangement (10) carries several tools (11).

4. Machining device according to one of the preceding claims, characterized in that the machining device (1 ) is designed for machining with only three machining axes (C, X, Z2) interpolating for the machining.

5. Machining device according to one of the preceding claims, characterized in that the machining device (1) is designed for machining workpieces (2) with a maximum diameter of 51 mm.

6. Machining device according to one of the preceding claims, characterized in that the machining device (1 ) is used to fix the The feed axis (Z1) is formed during machining, in particular during the shaping machining of an entire flat side (21) of the workpiece (2) with the same tool (11).

7. Machining device according to claim 6, characterized in that the machining device (1 ) is designed to fix the feed axis (Z1) exclusively by controlling the position without clamping.

8. Machining device according to one of the preceding claims, characterized in that the linear axis (Z2) is inclined relative to the feed axis (Z1), in particular in a vertical plane and / or by less than 10 degrees.

9. Machining device according to one of the preceding claims, characterized in that the linear axis (Z2) rises towards the spindle (8).

10. Machining device according to one of the preceding claims, characterized in that the spindle (8) or its housing is arranged immovably on the cross table (3) or a slide (4, 6) of the cross table (3).

11. Machining device according to one of the preceding claims, characterized in that the cross table (3) is attached to a frame or machine bed (13) of the machining device (1).

12. Machining device according to one of the preceding claims, characterized in that the cross table (3) has a hydrostatic bearing (5) for the transverse axis (X).

13. Machining device according to one of the preceding claims, characterized in that the bearing (7) of the cross table (3) for the feed axis (Z1 ) is arranged on the fluidic bearing (5) of the cross table (3) and / or that the feed axis (Z1 ) is arranged on the transverse axis (X).

14. Machining device according to one of the preceding claims, characterized in that the machining device (1 ) is designed such that the cross table (3) is movable only in the transverse axis (X) during or until the completion of the machining by means of the Fast-Tool arrangement (10).

15. Machining device according to one of the preceding claims, characterized in that the spindle (8) has an axially movable shaft (9) and forms the feed axis (Z1) of the cross table (3).

16. Machining device according to one of the preceding claims, characterized in that the machining device (1 ) is designed for additional machining of the workpiece (2) beyond face turning, in particular for edge machining, drilling and / or milling.

17. Machining device according to one of the preceding claims, characterized in that the machining device (1 ) is designed for machining or producing a rounded and / or undercut edge (20) of the workpiece (2) by means of the Fast-Tool arrangement (10).

18. Machining device according to one of the preceding claims, characterized in that the machining device (1) has at least one additional machining unit (16, 18), wherein the workpiece (2) can be moved to the at least one additional machining unit (16, 18) by means of the cross table (3).

19. Use of a cross table (3) for face turning of an optical workpiece (2), in particular an intraocular lens, contact lens or contact lens shape, wherein a spindle (8) holds the workpiece (2) for rotation about a rotary axis (C), wherein the spindle (8) with the workpiece (2) is moved by means of the cross table (3) along a feed axis (Z1) to a tool (11) of a fast-tool arrangement (10), characterized in that the cross table (3) moves and positions the spindle (8) with the workpiece (2) linearly along a transverse axis (X) which runs more precisely than the feed axis (Z1), wherein during or until the completion of the face turning the tool (11) of the fast-tool arrangement (10) is moved along a linear axis (Z2) and the cross table (3) is moved only in the transverse axis (X).

20. Use according to claim 19, characterized in that the delivery axis (Z1 ) is mounted on roller bearings and the transverse axis (X) is mounted hydrostatically.

21. Use according to claim 19 or 20, characterized in that a rounded and / or undercut edge (20) of the workpiece (2) is machined and / or produced by means of the Fast-Tool arrangement (10).

22. Use according to one of claims 19 to 21, characterized in that the Fast-Tool arrangement (10) carries several tools (11) and the tools (11) are used to machine a flat side (21) of the workpiece (2).

23. Use according to one of claims 19 to 22, characterized in that the machining device (1) for machining a flat side (21) of the workpiece (2) operates only three interpolating machining axes (C, X, Z2).

24. Use according to one of claims 19 to 23, characterized in that the machining device (1) is used only for machining workpieces (2) with a maximum diameter of 51 mm.

25. Use according to one of claims 19 to 24, characterized in that the processing device (1) is used only for processing intraocular lenses, contact lenses or contact lens shapes.

26. Use according to one of claims 19 to 25, characterized in that the machining device (1 ) fixes the feed axis (Z1 ) during the machining of a flat side (21 ) of the workpiece (2) with the same tool (11 ).

27. Use according to claim 26, characterized in that the processing device (1 ) fixes the feed axis (Z1 ) exclusively by regulating the position without clamping.

28. Method for face turning of an optical workpiece (2), in particular an intraocular lens, contact lens or contact lens shape, wherein the workpiece (2) is rotated about a rotary axis (C) during machining, characterized in that the workpiece (2) is first fed to a fast-tool arrangement (10) with a tool (11) via a roller-bearing feed axis (Z1) and subsequently the feed of the workpiece (2) along the feed axis (Z1) is no longer changed during face turning, but is used for axial movement during the During front rotation, only the tool (11) is moved along a more precise linear axis (Z2) by the Fast-Tool arrangement (10).

29. Method according to claim 28, characterized in that the workpiece is moved linearly transversely to the linear axis (Z2) of the tool (2) during machining by means of a fluidically, in particular hydrostatically, supported transverse axis (X).

30. Method according to claim 28 or 29, characterized in that the Fast-Tool arrangement (10) has an aerostatic or magnetic or rolling bearing-free bearing for a runner (12) carrying the tool (11).

31. Method according to one of claims 28 to 30, characterized in that the linear axis (Z2) rises towards the workpiece (2).

32. Method according to one of claims 28 to 31, characterized in that the Fast-Tool arrangement (10) carries several tools (11) and thus processes an end face (21) of the workpiece (2).

33. Method according to one of claims 28 to 32, characterized in that the machining device (1 ) with only three interpolating machining axes (C, X, Z2) machines an end face (21 ) of the workpiece (2).

34. Method according to one of claims 28 to 33, characterized in that the machining device (1) only machines workpieces (2) with a diameter of maximum 51 mm.

35. Method according to one of claims 28 to 34, characterized in that the machining device (1 ) fixes the feed axis (Z1 ) when machining an end face (21) of the workpiece (2) with the same tool (11 ) exclusively by controlling the position without clamping.

Images