METHOD AND DEVICE FOR THE FINE MACHINING OF AXICONS, FINE MACHINING MACHINE SUITABLE FOR THIS PURPOSE AND ITS USE

Description

TECHNICAL FIELD

[0001] The present invention relates generally to a method and apparatus for fine machining an axicon, as well as to a fine machining machine comprising such a device, and the use of this fine machining machine for fine machining an axicon. In particular, the invention relates to a method and apparatus for grinding, fine grinding, and / or polishing convex or concave conical lens surfaces, such as those to be mass-processed in precision optics.

[0002] In common technical usage, an "axicon" is a special lens that is conical or tapered on at least one of its two optically effective surfaces. Axicons can be convex or concave and made of any optical material—quartz glass, silicon dioxide, germanium, silicon, infrared glass (chalcogenide glass), Zerodur®, etc. Typical examples are plano-convex or plano-concave axicons. In the context of the present invention, an "axicon" is understood in the most general sense, regardless of the material, to mean any workpiece that has at least one surface section on at least one workpiece surface that is convex or concave conically shaped.Whenever a "conical surface" is referred to in the context of the present invention, this term should be understood in the broadest sense and - in addition to conical annular surfaces with any axial edge - also include non-annular, convex or concave curved surface sections of a workpiece with any edge on all sides, which satisfy the mathematical description of a right circular cone. STATE OF THE ART

[0003] Individual axicons, for example, generate a ring-shaped beam profile from a laser beam. The diameter of the ring beam depends on the cone angle of the axicon and increases with increasing distance between the axicon and the image plane, while the ring width remains constant. By combining an axicon with additional axicons or other lenses, a wide variety of beam profiles can be generated, as described, for example, in the publication DE 10 2015 201 639 B4.

[0004] Axicons are primarily used in beam shaping and various high-power laser applications. For example, axicons are used in the medical field in laser eye surgery. The ability to focus a laser beam into a ring-shaped beam profile is helpful for smoothing and ablating corneal tissue. By combining a convex and a concave axicon, as well as varying their spacing, the diameter of the ring can be adjusted for optimal power distribution.

[0005] Regarding the technical requirements placed on axicons, it should be noted that for the aforementioned applications, the permissible surface form deviations (RMSi = root-mean-square deviation according to DIN ISO 10110) range from RMSi ≤ 0.07 µm, in some cases even from RMSi ≤ 0.04 µm. The RMSi value describes the difference between the total fit error and the best-fit spherical surface. Accordingly, the precision machining of axicons places relatively high demands on the machining quality to be achieved.

[0006] The production or processing of the optically effective surfaces of axicons can be roughly divided into two processing phases: first, the shaping or pre-processing of the optically effective surfaces to create the desired macrogeometry, and then the fine machining of the optically effective surfaces to remove pre-processing traces and achieve the desired microgeometry. While the shaping or pre-processing of the optically effective surfaces of axicons can be carried out, depending on the material of the axicons, by milling, turning and / or grinding, or by primary or reshaping (see, for example,the publication US 2013 / 0272653 A1), the optically effective surfaces of axicons are usually subjected to a fine grinding, lapping and / or polishing process during fine machining, in which geometrically undefined cutting edges in the form of bound or loose grain are used in combination with a liquid between the workpiece and the tool, which are moved relative to each other.

[0007] In a known method for machining an axicon – similar to the process disclosed in DE 195 43 184 A1 – the conical surfaces of the axicon are finished using a smaller-diameter polishing tool with a conical outer surface. The polishing tool, which can be driven to rotate about its central axis, is positioned relative to the axicon, which can also be driven to rotate about its conical axis, such that the central axis of the polishing tool and the conical axis of the axicon lie in a plane, with the outer surface of the polishing tool being aligned with the conical surface of the axicon to be polished. As a result, the outer surface of the polishing tool and the conical surface of the axicon to be polished are in engagement along a portion of the outer surface of the polishing tool.During polishing, which takes place with the addition of a liquid polishing agent, the polishing tool and the axicon are driven in the same or (preferably) counter-rotating manner, whereby the polishing tool is additionally moved axially along its lateral surface section in contact with the conical surface of the axicon to be polished, until the conical surface of the axicon is polished.

[0008] By superimposing the two rotary movements of the polishing tool and the axicon, a relatively large polishing removal rate can be achieved, particularly with a counter-rotating rotary drive. However, the relative movement generated between the polishing tool and the axicon runs almost exclusively in the circumferential direction or, depending on the feed rate of the polishing tool, also slightly spiral-shaped along the contacting section of the lateral surface of the polishing tool. Furthermore, different removal rates are achieved in different polishing areas depending on the radial distance from the central or conical axis. With this known polishing process, there is a risk that, as a result of the aforementioned engagement conditions between the tool and the workpiece, structures with a preferred radial direction will form on the polished surface. This must be avoided, particularly in view of the desired machining and surface qualities described above.

[0009] Furthermore, the document DE 36 43 914 A1 discloses a method and a device for lapping or polishing very large optical components, such as those required for astronomical observations. Specifically, the main mirror of a telescope is mentioned here. In this prior art, the tool is designed as a strip-shaped, flexible membrane, 5 m long and 1 m wide in the disclosed example, which covers only a portion of the workpiece surface to be machined. On the side of the membrane facing away from the surface to be machined, a plurality of loading elements are provided, which are supported on the back of the membrane with individually controllable force and press it flatly against the surface to be machined with a specific pressure distribution.Furthermore, the previously known device for the workpiece has a rotary drive with an angle encoder connected thereto, the output of which is connected to a controller which serves to control the loading elements.

[0010] During the actual machining, the membrane is set into a radial oscillating motion above the workpiece surface to be machined, which rotates beneath it. The load elements pressing the membrane against the surface to be machined are fixed relative to the workpiece and do not participate in the oscillating motion of the membrane. The temporal progression of the pressure distribution is controlled depending on the angle of rotation between the workpiece and the tool, in particular to shorten the machining time. However, fine machining of axicons is neither addressed in this prior art nor is it possible with the pressure distribution concept disclosed here, especially with regard to the conical geometry to be finely machined on the axicon, its typical dimensions, and the machining accuracies achievable here.

[0011] Furthermore, according to the document DE 10 2014 015 053 A1, a device for fine machining optically effective surfaces on ophthalmic lenses as workpieces comprises a workpiece spindle projecting into a work space, via which a workpiece to be polished can be driven in rotation about a workpiece rotation axis, and two tool spindles assigned to the workpiece spindle and projecting into the work space opposite one another. An elastic polishing tool is mounted on each of the tool spindles, which can be driven in rotation about a tool rotation axis and can be axially advanced along the tool rotation axis. Furthermore, the tool spindles are jointly movable relative to the workpiece spindle along a linear axis running essentially perpendicular to the workpiece rotation axis and can be pivoted about various pivoting adjustment axes running essentially perpendicular to the workpiece rotation axis and essentially perpendicular to the linear axis.The tool spindles are arranged one behind the other in the direction of the linear axis. This arrangement makes the device very compact and versatile, allowing it to be used for a variety of polishing processes and strategies in ophthalmic optics.

[0012] Furthermore, EP 3 357 640 B1 discloses a translatory tool module for fine machining, comprising at least one fine machining element having a contact pressure stroke, at least one contact pressure system for influencing a contact pressure of the at least one fine machining element on a workpiece surface to be machined, and drive means for driving the at least one fine machining element. The at least one fine machining element is arranged on at least one linearly guided translation unit driven by the drive means.Furthermore, in this prior art, at least one transmission device is provided which is arranged in the translation unit or in at least one of the translation units and serves to transmit a force to the finishing element or to at least one of the finishing elements, which transmission device is a pressure transmission device comprising a piston-cylinder system and operated with fluid pressure or an electrically operated force transmission device.

[0013] A special feature of this tool module is that a machine interface is provided for connection to a machine, in particular a machine tool or a robot, wherein the aforementioned drive means comprise conversion means for converting a rotational movement of a machine element into the linearly guided translational movement of the at least one translation unit, the machine interface is designed for connection to a spindle and the conversion means are provided for converting a rotation of the spindle.

[0014] Finally, from the document DE 10 2012 108 594 A1 a device for finishing workpieces is known, comprising a tool holder which has an interface with a rotatably mounted spindle for connection to a motor spindle of a machine tool and an output shaft, a tool holder for at least one finishing tool and an oscillation head with an eccentric arrangement for transforming rotational movements of the output shaft into oscillation movements of the tool holder.

[0015] A special feature of this device is that the output shaft is axially displaceable and arranged in a form-fitting manner within a hollow shaft, which is set in rotation by the rotation of the spindle. Furthermore, the oscillation head is guided on the tool holder for linear movement in the axial direction of the output shaft, with a pressure device acting in the feed direction of the tool being assigned to the oscillation head. Finally, the eccentric arrangement of the oscillation head is arranged on one end of the output shaft and forms a functional unit with it that can be displaced relative to the hollow shaft. TASK

[0016] The invention is based on the object of providing a method for fine machining an axicon that is as simple as possible and addresses the problems mentioned above with regard to the prior art. In particular, the method should enable the fastest possible fine machining of an axicon with high machining quality, without the risk of forming undesirable structures or other surface defects on the finely machined conical surface of the axicon. The object of the invention further includes specifying a device for improved fine machining of an axicon that is as simple as possible to use and requires little setup effort, as well as a suitable fine machining machine, including its use for the high-quality fine machining of an axicon. PRESENTATION OF THE INVENTION

[0017] These objects are achieved by a method having the method steps according to patent claim 1, a device having the features of patent claim 4, a finishing machine having the features of patent claim 10, and the use of a finishing machine according to patent claim 12. Advantageous embodiments of the invention are the subject of the dependent patent claims.

[0018] According to the invention, in a method for fine machining an axicon having at least one concave or convex conical surface with a conical axis and a conical angle, it is provided that, by means of a tool having a machining area for linear engagement with the conical surface to be machined, which has a front end with respect to the conical axis, using geometrically indeterminate cutting edges in the form of bound or loose grain in combination with a liquid in the machining area of ​​the tool, material removal is produced on the conical surface of the axicon by a relative cutting speed which results solely from a rotary movement of the axicon about the conical axis and a relative oscillating linear movement along an oscillation axis of the tool which is in linear engagement with the conical surface to be machined,in which the front end of the machining area, seen in a plan view, moves back and forth in a radial direction with respect to the cone axis.

[0019] As investigations by the inventors have shown, radial groove structures, surface form defects, high surface roughness, and angular errors on or at the conical surface of the axicon are reliably avoided by the tool oscillating only transversely to the rotational movement of the axicon in the direction of the conical angle, which only contacts the conical surface of the axicon to be machined in a linear manner. As a result of the method according to the invention, the machined conical surface of the axicon is cleanly smoothed. Relatively high stock removal rates and thus the fastest possible fine machining can be easily achieved by appropriately selecting the rotational speed of the axicon around the conical axis and / or the oscillation frequency of the tool over the conical surface of the axicon to be machined.With the linear support of the tool on the conical surface of the axicon provided according to the invention, it is also advantageously possible to give the tool a certain preload by appropriately positioning the tool relative to the conical surface at its front or rear end with respect to the conical axis and thus to influence the pressure distribution over the length of the tool, whereby an angle correction on the conical surface of the axicon is also possible within limits.

[0020] In an expedient embodiment of the method, a two-stage procedure can be provided in which a relative alignment and feed movement (1st stage) is initially generated between the axicon and the tool in accordance with the cone angle, as a result of which the machining area of ​​the tool comes into linear engagement with the conical surface of the axicon, with the front end of the machining area facing the cone axis, whereupon the relative oscillating linear movement along the oscillation axis as a feed movement (2nd stage) is generated between the axicon, which is driven to rotate about the cone axis or about a workpiece rotation axis, and the tool.Stage) is generated, in which the front end of the machining area moves several times over the conical surface from an outer edge region of the conical surface in a radial direction with respect to the conical axis at least close to the conical axis and back again during one revolution of the axicon around the conical axis, as seen in plan view.

[0021] In this context, "at least close to the cone axis" means that during the feed movement, or more precisely with a suitable oscillation stroke of the feed movement, it must be ensured that the entire conical surface of the axicon is swept over by the tool and thus finely machined. In the case of a convex conical surface, this can include a feed movement of the tool beyond the cone axis. In the case of the conical surface of a concave axicon, which, as a result of its pre-machining to create the desired macrogeometry in the area of ​​the cone axis, usually has a passage extending along the cone axis with a small diameter of, for example, 2 mm, the feed movement in the direction of the cone axis ends when the tool reaches this passage with the front end of its machining area.In other words, in the case of a concave conical surface, it must be ensured that the tool does not oscillate beyond the cone axis during its feed movement with the front end of its machining area.

[0022] In further pursuing the inventive concept, it can be provided that during the fine machining of the conical surface, the rotational speed of the axicon around the conical axis and the frequency of the relative oscillating linear movement along the oscillation axis of the tool over the conical surface are coordinated in such a way that the number of back and forth movements of the tool per revolution of the axicon is not an even number. This simply prevents the tool from being in exactly the same radial position after one revolution of the axicon around the conical axis as it was at the beginning of this revolution of the axicon. Thus, during the fine machining, with each revolution of the axicon around the conical axis, a continuous "track change" of the tool advantageously takes place on the finely machined conical surface. This promotes very good surface quality.As far as the number of back and forth movements of the tool per revolution of the axicon is concerned, this can basically be an integer or a non-integer, so that the reversal points of the tool are located at different angular positions of the axicon with respect to the cone axis.

[0023] As investigations by the inventors have shown, it is advantageous if during the fine machining of the conical surface the number of back and forth movements of the tool per revolution of the axicon around the conical axis is greater than or equal to 3 and less than or equal to 7. With an appropriate ratio of frequency to speed, the dwell times of the machining area of ​​the tool on a surface section of the conical surface of the axicon are neither too long nor too short, so that a very good, ie . uniform finishing results can be achieved.

[0024] A device for fine machining an axicon having at least one concave or convex conical surface with a conical axis and a conical angle, with a tool having a machining area for linear engagement with the conical surface to be machined, comprises, according to a further aspect of the invention, a base adapted to be flanged to a tool spindle of a fine machining machine, a guide arrangement mounted on the base, which longitudinally guides a tool carriage which is drivable in an oscillating manner along an oscillation axis and which carries the tool for fine machining the axicon, a gear mechanism adapted to convert a rotary movement generated by the tool spindle into a reciprocating linear movement of the tool carriage along the oscillation axis, and for this purpose has a rotary disk which can be connected to the tool spindle for driving purposes,which is rotatable about a rotational axis and to which a guide pin is mounted radially offset with respect to the rotational axis, which guide pin engages in a slot formed in the tool slide extending transversely to the oscillation axis, so that the tool slide can be driven in an oscillating manner with a predetermined stroke along the oscillation axis, wherein the rotating disk is provided with a plurality of fastening holes for the guide pin, which have a different radial distance from the rotational axis, so that the stroke of the tool slide is adjustable, and / or wherein the tool slide has at least two slots extending parallel to one another for the selective engagement of the guide pin, via which an axial relative position of the tool slide with respect to the rotational axis can be adjusted.

[0025] Thus, for the fine machining of an axicon, which can be carried out as described above, no specially designed fine machining machine is required; rather, a conventional grinding or polishing machine can be used, to whose tool spindle the inventive device for fine machining of an axicon is flange-mounted with its base. Rapid setup of an existing grinding or polishing machine for the fine machining of axicons is thus possible without major setup effort. During the actual fine machining, the existing machine axes of the grinding or polishing machine are then advantageously used to effect the infeed and alignment of the tool with its machining area relative to the conical surface to be machined on the axicon.

[0026] Since the gear mechanism is provided for the oscillating drive of the tool slide, which is adapted to convert the rotary movement generated by the tool spindle of the finishing machine into the reciprocating linear movement of the tool slide along the oscillation axis, the device-related expenditure is advantageously low and there is a simple possibility of retrofitting an existing finishing machine with the device described above for the finishing of an axicon.

[0027] In a particularly simple structural design, the gear mechanism comprises the rotary disk, which is drive-connectable to the tool spindle of the precision machining machine and rotatable about the rotation axis, with the guide pin mounted thereon radially offset with respect to the rotation axis, which engages in the slot formed in the tool slide extending transversely to the oscillation axis, so that the tool slide can be driven in an oscillating manner with a predetermined stroke along the oscillation axis.

[0028] To ensure the most flexible possible use of the device for the fine machining of axicons with different geometries, it is advantageous for the rotating disk to have several mounting holes for the guide pin at different radial distances from the rotation axis, so that the stroke of the tool slide can be adjusted in stages, and / or for the tool slide to have at least two parallel slots for the selective engagement of the guide pin, via which the axial relative position of the tool slide with respect to the rotation axis can be adjusted. During the fine machining of a specific axicon, the guide pin then remains in the slot of the tool slide assigned to it before the fine machining of this axicon.

[0029] Furthermore, the present invention also provides a fine machining machine comprising a tool spindle with a tool rotation axis C and a workpiece spindle with a workpiece rotation axis D, which project into a working space delimited by a machine bed and are movable relative to one another at least in an imaginary plane YZ spanned by the tool rotation axis and the workpiece rotation axis (Y-axis, Z-axis) and are pivotable relative to one another with respect to a pivot axis A which runs perpendicular to the plane YZ, wherein the device proposed here for fine machining an axicon is mounted on an end of the tool spindle facing the workpiece spindle.

[0030] In a particularly rigid design specifically created for high precision requirements in optics manufacturing, the machine bed of the precision machining center can have two side walls between which the work space is formed and which support a gantry that can be moved in a longitudinal direction along the Y-axis, on which gantry the tool spindle is guided so that it can be moved along the Z-axis at least in a direction perpendicular to the longitudinal direction along the Y-axis, and wherein a yoke carrying the workpiece spindle is provided in the work space and is mounted on the side walls so that it can rotate about the pivot axis A, as is described, for example, in the German patent DE 100 29 967 B4 of the present applicant.

[0031] Furthermore, the present invention provides a use of the above-described finishing machine, on whose tool spindle the proposed device for finishing an axicon is mounted, for the finishing of an axicon having at least one concave or convex conical surface with a conical axis and a conical angle.

[0032] Furthermore, as regards the device for fine machining of an axicon, its guide arrangement can, in a particularly simple structural design, comprise a guide frame to which guide rails for the tool carriage are attached on opposite sides.

[0033] The guide rails can generally be those with rolling elements, which are particularly smooth-running. However, with a view to low costs and a simple design of the device, it is preferred if the guide rails, which are made of a plain bearing material such as sintered bronze, a copper alloy, a suitable plastic such as polytetrafluoroethylene (PTFE) or Teflon®, or the like, each have a V-shaped groove on mutually facing sides, wherein the tool carriage each has a wedge-shaped guide section on mutually opposite sides, and wherein the wedge-shaped guide sections of the tool carriage are slidably received in the V-shaped grooves of the guide rails.In such a design, the guide arrangement is particularly insensitive to the abrasive polishing agent, i.e., it is low-wear, is easy to clean and, in order to ensure sufficient smooth running, does not require any additional lubrication with grease or similar substances, which could be detrimental to a good polishing result.

[0034] In a particularly simple variant of the device for fine machining an axicon, the tool can be rigidly connected to the tool carriage, possibly with the aid of a spacer. In such a case, a certain degree of sensitivity in engaging and maintaining the tool's machining area with the conical surface of the axicon to be fine-machined must be achieved via the movement axes of the fine-machining machine, which requires suitable sensor technology on the fine-machining machine.

[0035] In comparison, however, a preferred embodiment of the device is one in which a connecting part with a further guide arrangement is attached to the tool carriage. This guide arrangement serves to movably guide the tool in a direction transverse to the oscillation axis of the tool carriage. The tool is subjected to a force in the direction transverse to the oscillation axis of the tool carriage, which pushes the tool away from the connecting part. Thus, the device itself does not have a "hard" guide, but rather advantageously has a certain softness, so that the tool can deflect against the applied force in the direction transverse to the oscillation axis during fine machining of the conical surface, which allows for fine machining that is particularly gentle on the macrogeometry of the conical surface.

[0036] In principle, the aforementioned force can be generated in the direction transverse to the oscillation axis, e.g., by means of one or more springs or by using a rubber or elastic foam or the like, which acts in a pushing or pulling manner between the connecting part and the tool. Particularly with regard to low wear and easy cleaning, in a preferred embodiment of the device for fine machining an axicon, the aforementioned force is applied by at least two mutually repelling magnets arranged between the connecting part and the tool. While such magnets are exposed to the abrasive polishing agent in this position, they are not attacked by it.

[0037] For the movable guidance of the tool transversely to the oscillation axis, the additional guide arrangement can, in principle, comprise any linear guide, for example, a linear guide with a profiled guide rail on the connecting part and a roller-bearing carriage running thereon on the tool side. However, particularly with a view to minimizing the installation space required, it is preferred for the additional guide arrangement to comprise at least one guide cylinder. For example, two parallel cylinder bores can be formed in the connecting part, each of which accommodates a guide rod that is suitably attached to the tool.

[0038] Viewed along the oscillation axis of the tool, the connecting part can in principle be mounted in a fixed axial position on the tool carriage, just as the tool can be arranged in a fixed axial position relative to the connecting part. However, a preferred embodiment of the device is one in which the connecting part is attached to the tool carriage so that its axial position along the oscillation axis can be changed, and / or the tool is mounted on the additional guide arrangement so that its axial position along the oscillation axis can be changed. This provides further options for influencing the axial position of the tool during the fine machining of an axicon, which in turn is particularly advantageous with regard to the most flexible use of the device for the fine machining of axicons with different geometries.

[0039] Various designs are conceivable for the tool itself, in which the machining area of ​​the tool ensures linear engagement with the conical surface of the axicon to be machined. For example, in a first variant, the tool can essentially have the shape of an isosceles triangle when viewed from above, with a machining area that has a front end at one tip of the triangle and allows linear engagement with the conical surface of the axicon to be machined on each of the long sides of the triangle facing away from one another. Such a tool is intended for machining concave axicons. Due to the double linear engagement with the conical surface of the concave axicon to be machined on both long sides of the tool, this tool advantageously offers a high stock removal rate.

[0040] In a second, alternative variant, the tool can be essentially strip-shaped, with a machining area that has a front end on a transverse side of the tool and allows linear engagement with the conical surface of the axicon to be machined along a longitudinal side of the tool. Such a tool is equally suitable for machining concave and convex axicons, but has a lower material removal rate than the tool according to the first variant above.

[0041] Finally, regarding the processing area of ​​each tool, it should be noted that the tool in question is equipped with a suitable, commercially available polishing agent carrier—such as a polishing felt or polishing film—that is glued to the tool. This polishing agent carrier is not specifically mentioned or shown below.

[0042] Further features, properties and advantages of the method according to the invention, the device according to the invention and the precision machining machine equipped according to the invention and their use will become apparent to the person skilled in the art from the following description of preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The invention will be explained in more detail below using preferred embodiments with reference to the accompanying, partially schematic drawings, in which identical or corresponding parts or sections are provided with the same reference numerals. In the drawings: Fig. 1 a perspective view of a finishing machine for optical workpieces equipped according to the invention, diagonally from above / front left, with a view into a working area of ​​the finishing machine and onto a device according to the invention for finishing an axicon, which is arranged there at one end of aFig. 1 upper tool spindle is mounted, which is one in Fig. 1 lower workpiece spindle in a pivoting yoke of the finishing machine; Fig. 2 a plan view of the Fig. 1 shown finishing machine from above in Fig. 1 ; Fig. 3a scale comparison of the Fig. 1 and 2 enlarged, perspective view of separately shown assemblies of the finishing machine according to Fig. 1 from diagonally above / front left, namely a vertical slide with the tool spindle and the yoke with the workpiece spindle as well as the device arranged therebetween for the fine machining of an axicon, wherein a linearly oscillating driven, essentially triangular tool of the device is in machining engagement with a rotationally driven, concave axicon held on the workpiece spindle; Fig. 4 a compared to the scale of the Fig. 3enlarged perspective view of separately shown components of the finishing machine according to Fig. 1 from diagonally above / front left, which differs from the view according to Fig. 3 only differs in that the vertical slide with the tool spindle except for its chuck has been omitted in order to provide a view of the device for fine machining of an axicon; Fig. 5 a scaled-down view of the Fig. 4 enlarged perspective view of the device for fine machining of an axicon according to Fig. 1 from diagonally below / front left, which - except for the chuck of the tool spindle - from the finishing machine according to Fig. 1 shown separately; Fig. 6 a side view of the Fig. 5 shown device for fine machining of an axicon; Fig. 7 a bottom view of the in Fig. 5 shown device for fine machining of an axicon from below in Fig. 6; Fig. 8 a rear view of the Fig. 5 shown device for fine machining of an axicon from left to Fig. 6 ; Fig. 9a scaled view of the Fig. 8 enlarged sectional view of the Fig. 5 shown device for fine machining of an axicon - without the chuck of the tool spindle - according to the cutting line IX-IX in Fig. 8 , where in a lower part of the Fig. 9 illustrates how the tool can be mounted offset on the device; Fig. 10bis Fig. 15 schematic bottom views of the Fig. 5 shown device for fine machining of an axicon, similar to the bottom view according to Fig. 7 , which illustrate some of the possibilities of influencing the axial position and stroke of the tool indicated by dashed lines in the direction of oscillation; Fig. 16 a perspective view of another, essentially strip-shaped tool for the Fig. 5shown device for fine machining of an axicon from diagonally above / front right; Fig. 17 a rear view of the tool according to Fig. 16 from behind in Fig. 16 ; Fig. 18 a side view of the tool according to Fig. 16 from the right into Fig. 17 ; Fig. 19 a top view of the tool according to Fig. 16 from above in Fig. 17 ; Fig. 20 a schematic plan view of a concave axicon, which is formed by means of the Fig. 5 shown, essentially triangular tool according to the invention; Fig. 21 is a schematic sectional view of the Fig. 20 shown concave axicons / triangular tool according to the cutting line XXI-XXI in Fig. 20 ; Fig. 22 a schematic plan view of a concave axicon, which is formed by means of the Fig. 16 to 19 shown, essentially strip-shaped tool is machined according to the invention; and Fig. 23 is a schematic sectional view of the Fig. 22shown concave axicons / strip-shaped tool according to the cutting line XXIII-XXIII in Fig. 22 .

[0044] Regarding the drawings, it should be noted at this point that the representation of the finishing machine equipped according to the invention is made in a rectangular Cartesian coordinate system, in which the letter x denotes the width direction, the letter y the length direction and the letter z the height direction of the finishing machine. Fig. 1 and 2In order to provide a clear view of the essential components and assemblies of the precision machining machine and to simplify the illustration, the operating unit and control system, cladding parts, door mechanisms and panes, storage areas for workpieces and tools, the supply devices (including lines, hoses and pipes) for electricity, compressed air and polishing agents, the polishing agent return line and the measuring, maintenance and safety devices inside the machine have been omitted because they do not appear necessary for understanding the invention and are familiar to the person skilled in the art anyway. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] In the Fig. 1 and 2 is - as a possible application or location of a further below, in particular with reference to the Fig. 3 to 15 The device 10 for fine machining an axicon L, which is explained in detail below and which is produced according to the Fig. 20 to 23at least one concave (or alternatively convex) conical surface KF with a cone axis KA and a cone angle α - a CNC-controlled fine machining machine, i.e. a machine for grinding, fine-grinding and / or polishing the surfaces and edges of optical workpieces, generally designated by the reference numeral 12. The basic structure of this fine machining machine 12 is explained in detail in the German patent DE 100 29 967 B4 of the present applicant, which is why the fine machining machine 12 will only be described below to the extent that it appears necessary for understanding the present invention. Furthermore, with regard to the structure and function of the fine machining machine 12, in order to avoid repetition, express reference is made to the patent specification DE 100 29 967 B4.

[0046] The precision machining machine 12 generally has a tool spindle 14 with a speed-controlled tool rotation axis C and a workpiece spindle 16 with a workpiece rotation axis D whose rotation angle is controlled. The tool spindle 14 and the workpiece spindle 16 project into a work space 18 which is delimited by a machine bed 20 formed from polymer concrete. The tool spindle 14 and the workpiece spindle 16 - as will also be described in more detail below - can be moved relative to one another in a position-controlled manner (linear axis Y, linear axis Z) in an imaginary plane YZ spanned by the tool rotation axis C and the workpiece rotation axis D, and can be pivoted relative to one another in a controlled manner in the rotation angle with respect to a pivot axis (A-axis) which runs perpendicular to the plane YZ. The device 10 for fine machining of axicons L is mounted on one end of the tool spindle 14 facing the workpiece spindle 16.

[0047] For this purpose, the device 10 generally has a base 22 or base plate adapted to be flanged to the tool spindle 14 of the finishing machine 12. A guide assembly 24 is mounted on the base 22, which longitudinally guides a tool carriage 26 that can be driven in an oscillating manner along an oscillation axis R. The tool carriage 26 itself carries a tool W1 or W2 for the finishing of axicons L.

[0048] The Fig. 1 to 15 , 20 and 21 show the tool W1 according to a first variant, in which the tool W1, viewed from above, essentially has the shape of an isosceles triangle. This tool W1 has a machining area BB, which has a front end EB at a tip of the triangle and a linear engagement LE on each of the long sides of the triangle facing away from each other (cf. Fig. 20 ) with the conical surface KF of the axicon L to be machined.

[0049] The Fig. 16 to 19 , 22 and 23 However, the tool W2 is shown according to a second variant, in which the tool W2 is essentially strip-shaped. This tool W2 has a machining area BB, which has a front end EB on a transverse side of the tool W2 and a linear engagement LE along a longitudinal side of the tool W2 (see the Fig. 23 ) with the conical surface KF of the axicon L to be machined.

[0050] In addition to the possibility of a linear engagement LE of the respective machining area BB with the conical surface KF of the axicon L to be machined, tools W1 and W2 have in common that the respective machining area BB is provided with a commercially available polishing agent carrier (not shown in the figures). The polishing agent carrier can be, for example, a so-called "polishing film" or a suitable foam with or without a carrier material, which is glued to the machining area BB of the tool W1, W2 with a certain lateral overhang using a commercially available adhesive. Suitable polishing films made of polyurethane (PUR) in a thickness of 0.5 to 1.3 mm are available from James H. Rhodes & Company, Vernon, USA, while suitable foams can be obtained from Getzner Werkstoffe GmbH, Oberhaching, Germany.For bonding these polishing agent carriers to the processing area BB of the respective tool W1, W2, a commercially available adhesive of the brand Pattex ®< from Henkel AG & Co. KGaA, Düsseldorf, Germany, is suitable.

[0051] After this general overview of the finishing machine 12, the device 10 mounted thereon for the finishing of axicons L and the tool W1, W2 moved thereby, we return to the Fig. 1 and 2Regarding the precision machining machine 12, it should also be noted that its machine bed 20 has two parallel side walls 28, between which the working space 18 is formed. The side walls 28 support a gantry 30 which can be moved in a position-controlled manner in the longitudinal direction y of the precision machining machine 12 along the linear axis Y. On the gantry 30, a horizontal slide 32 is guided so as to be longitudinally displaceable in the width direction x of the precision machining machine 12 and can be moved in a position-controlled manner along the linear axis X. On the horizontal slide 32, in turn, a vertical slide 34 is guided so as to be longitudinally displaceable in the height direction z of the precision machining machine 12 and can be moved in a position-controlled manner along the linear axis Z and carries the tool spindle 14.

[0052] On the workpiece side, a yoke 36 supporting the workpiece spindle 16 is provided in the work space 18. The yoke 36 is mounted on the side walls 28 of the machine bed 20 for rotation about the pivot axis A and can be driven or held at a controlled angle of rotation by means of a torque motor and associated brake (not visible in the figures). Counterweights 38 provided on both sides ensure weight compensation for the yoke 36.

[0053] Finally, at the mutually facing ends of the tool spindle 14 and the workpiece spindle 16, these are each provided with a chuck 40 and 42, respectively, which can be designed, for example, in a hydraulic expansion design. A cylindrical shaft of a tool (not shown) can be held in a conventional manner with the chuck 40 of the tool spindle 14. The chuck 42 of the workpiece spindle 16 is designed to hold an optical workpiece, in the present application an axicon L, on a cylindrical edge surface RF of the axicon L (cf. Fig. 20 to 23 ) to grasp and hold.

[0054] As far as the kinematics of the precision machining machine 12 are concerned, it is apparent to a person skilled in the art that, on the tool side, the end of the tool spindle 14 projecting into the work space 18 can be spatially moved and positioned within the work space 18 by means of the three linear axes X, Y, and Z. Furthermore, the chuck 40 can be driven to rotate about the tool rotation axis C by means of the tool spindle 14. On the workpiece side, the end of the workpiece spindle 16 projecting into the work space 18 can be adjusted or pivoted at a defined angle relative to the tool spindle 14 by means of the pivot axis A. Furthermore, the chuck 42 can be driven to rotate about the workpiece rotation axis D by means of the workpiece spindle 16 and positioned in the angular position.

[0055] Further details of the device 10 for fine machining of Axicons L are given in the Fig. 3 to 9 As can be seen from the Fig. 4 , 5 and 9As can be seen, the base 22 has a circular hole 44 through which the work area end of the tool spindle 14 with the chuck 40 extends when the device 10 is mounted on the tool spindle 14. The top side of the base 22 forms a flat flange surface, which can be applied from below to a spindle housing of the tool spindle 14. In the illustrated embodiment, two fastening screws 46 are provided for fastening the base 22 to the tool spindle 14 (see Fig. 4 ), which in the assembled state of the device 10 pass through associated fastening holes in the base 22 and are screwed into associated threaded holes (not shown) in the spindle housing of the tool spindle 14.

[0056] The guide arrangement 24 for the tool carriage 26 mounted on the base 22 has a guide frame 48 which is rectangular in plan view and which is fastened to the base 22 by means of screws via fastening angles 50 arranged at the corners of the guide frame 48, so that the guide frame 48 extends parallel to and at a distance from the base 22. Guide rails 52 for the tool carriage 26 are attached to the guide frame 48 on opposite sides by means of screws. As best shown in the Fig. 5 and 8As can be seen, the guide rails 52, which are made of a plain bearing material, each have a substantially V-shaped groove 54 on mutually facing sides, while the tool carriage 26 has a wedge-shaped guide section 56 on mutually opposite sides, wherein the wedge-shaped guide sections 56 of the tool carriage 26 are slidably received in the V-shaped grooves 54 of the guide rails 52. It can be seen that the tool carriage 26 can thus be moved axially back and forth in the guide frame 48 (oscillation axis R).

[0057] In the illustrated embodiment, a gear mechanism 58 is provided for the oscillating drive of the tool carriage 26, which is adapted to convert a rotary movement generated by the tool spindle 14 of the finishing machine 12 into a reciprocating linear movement of the tool carriage 26 along the oscillation axis R. For this purpose, the gear mechanism 58 is designed in the manner of an eccentric drive and has a rotary disk 60 which can be connected to the tool spindle 14 of the finishing machine 12 and which is rotatable about a rotation axis, here the tool rotation axis C. As the Fig. 9 shows, the rotating disk 60 has a cylindrical clamping extension 62 or pin, via which the rotating disk 60 can be clamped on the chuck 40 of the tool spindle 14.

[0058] A guide pin 64 is mounted on the rotary disk 60, radially offset with respect to the rotation axis C, which engages in a slot 66 formed in the tool slide 26 and extends transversely to the direction of movement of the tool slide 26, i.e. to the oscillation axis R. As can be seen from the Fig. 9 to 13 , a central axis of the guide pin 64 has a radial distance r1 from the rotation axis C of the rotation disk 60.

[0059] The Figs. 10 and 11 also illustrate what happens in this embodiment of the gear mechanism 58 when the rotary disc 60 moves from its rotational angle position according to Fig. 10 rotates 180° around the rotation axis C, so that it has the angle of rotation position according to Fig. 11achieved, namely the tool slide 26, which is positively guided between the guide rails 52 of the guide arrangement 24, is moved by the Fig. 10 shown left axial position of the tool slide 26 in the guide frame 48 by a stroke H1 to the right into the Fig. 11 shown right axial position of the tool slide 26 in the guide frame 48. The stroke H1 of the tool slide 26 is twice as large as the radial distance r1 between the guide pin 64 and the rotation axis C of the rotating disk 60.

[0060] If the rotation disc 60 then moves from its rotation angle position according to Fig. 11 is rotated further by 180° around the rotation axis C, so that it regains its rotation angle position according to Fig. 10reached, the tool slide 26 moves due to the positive engagement of the guide pin 64 with the slot 66 from the position shown in Fig. 11 shown right axial position of the tool slide 26 in the guide frame 48 by the stroke H1 to the left back to the position shown in Fig. 10 illustrated left axial position of the tool slide 26 in the guide frame 48. It can be seen that in this way a rotation of the rotary disk 60 about the rotation axis C in the guide frame 48 forces an oscillating back and forth movement of the tool slide 26 with a predetermined stroke H1 along the oscillation axis R.

[0061] How best in Fig. 9As can be seen, the rotating disk 60 in the illustrated embodiment is provided with a plurality of fastening bores 68, 70, 72 for the guide pin 64. Each of these fastening bores 68, 70, 72 is designed here as a threaded bore into which the guide pin 64 can be screwed with a threaded extension 74. The center axes of the fastening bores 68, 70, 72 have a different radial distance r1, r2 or r3 from the rotation axis C, so that by displacing the guide pin 64, a stroke H1, H2 or H3 of the tool carriage 26 in the guide frame 48 can be adjusted in steps.

[0062] In the illustrated embodiment, the tool slide 26 is further provided with a further slot 76 extending parallel to the slot 66. The guide pin 64 can be selectively engaged with one or the other of the slots 66, 76, whereby an axial relative position of the tool slide 26 with respect to the rotational axis C of the rotating disk 60 can be adjusted in two stages.

[0063] The Figs. 12 and 13 illustrate this in comparison to the Figs. 10 and 11in the event that the guide pin 64 on the rotary disk 60 is not displaced, ie, its threaded extension 74 is reattached to the mounting hole 68, but its free end is engaged with the other slot 76 in the tool slide 26. In this case, too, a rotation of the rotary disk 60 about the rotation axis C causes an oscillating back and forth movement of the tool slide 26 with the stroke H1 in the guide frame 48 (see Fig. 13 ), but with axial end positions of the tool slide 26, which are different from the axial end positions with the slot engagement according to the Figs. 10 and 11 This results in the two axial end positions of the tool slide 26 - compared to the basic configuration according to the Figs. 10 and 11 - an offset V3 or V4 of the front end EB of the tool W1, which is connected to the tool carriage 26 and which is in the Fig. 10 to 15indicated by dashed lines.

[0064] A combination of the adjustment measures described above - changing the stroke H1, H2, H3 of the tool slide 26 by moving the guide pin 64 in the fastening holes 68, 70, 72 of the rotary disk 60, changing the axial start or reversing positions of the tool slide 26 in the guide frame 48 by selecting a different slot 66, 76 of the tool slide 26 for engagement with the guide pin 64 - is described in the Figs. 14 and 15 In this case, the guide pin 64 is located in relation to the Figs. 10 and 11 in engagement with the other slot 76 of the tool carriage 26, is compared to the Figs. 12 and 13 but at the same time also screwed into another mounting hole 70 in the rotating disk 60. This results in different settings compared to the Fig. 10 to 13a larger stroke H2 and other axial start or reversal positions of the tool slide 26, as can be seen from a "vertical" comparison of the Figs. 10, 12 and 14 or 11, 13 and 15, which show aligned guide frames 48 for this purpose. This results in an offset V5 or V6 at the front end EB of the tool W1 for the two axial end positions of the tool slide 26.

[0065] It should also be mentioned at this point that the guide frame 48 is provided on its short sides with slot-like openings 78 which are dimensioned such that the tool carriage 26, during its back and forth movement in the guide frame 48, can possibly enter one of the openings 78 in accordance with its stroke H1, H2, H3 and / or its axial relative position with respect to the rotational axis C of the rotary disk 60, which is not shown in the figures.

[0066] Furthermore, in particular the Fig. 9As can be seen, a cuboid-shaped connecting part 80 for the tool W1 or W2 is fastened to the tool carriage 26 on the side of the tool carriage 26 facing away from the rotating disk 60. For this purpose, three fastening bores 82 with an internal thread are formed in the tool carriage 26 in the illustrated embodiment, which are arranged one behind the other at the same distance from one another along the oscillation axis R, while the connecting part 80 has two associated blind bores 84 with an internal thread. Grub screws 86 are screwed into two adjacent fastening bores 82 of the tool carriage 26 and extend into the blind bores 84 of the connecting part 80 in order to fix the connecting part 80 to the tool carriage 26.

[0067] Since three – or possibly more – fastening holes 82 are provided in the tool carriage 26, the connecting part 80 can be fastened to the tool carriage 26 in a manner that is variable in its axial position along the oscillation axis R. This in turn influences the axial relative position of the tool W1 or W2, as seen along the oscillation axis R, with respect to the rotation axis C of the rotary disk 60. Fig. 10 to 15 the grub screws 86 are indicated by filled circles; the axial position of the connecting part 80 with respect to the tool slide 26 corresponds to that shown in Fig. 9 constellation shown.

[0068] In Fig. 9It can also be seen that the connecting part 80 is provided with a further guide arrangement 88, which serves to movably guide the tool W1, W2 in a direction transverse to the oscillation axis R of the tool carriage 26. In the illustrated embodiment, the further guide arrangement 88 has two guide cylinders 90, each extending parallel to one another perpendicular to the oscillation axis R. Each guide cylinder 90 comprises a cylinder bore 92 in the connecting part 80, designed as a blind bore, and a cylinder pin 94, which is received in the respective cylinder bore 92 in a piston-like manner and is axially displaceable.

[0069] At its end facing the tool slide 26, each cylindrical pin 94 is provided with an elongated hole 96. Near the closed ends of the cylindrical bores 92, threaded bores 98 extending transversely to the cylinder bores 92 are also provided in the connecting part 80, into each of which a cap screw 100 is screwed, which penetrates the elongated hole 96 in the associated cylindrical pin 94. It can be seen that the combination of the elongated hole 96 and the cap screw 100 allows a limited axial displacement of the respective cylindrical pin 94 in the associated cylinder bore 92, although the cap screws 100 prevent the cylindrical pins 94 from being pulled out of the cylinder bores 92.

[0070] At its end facing away from the tool carriage 26, each cylindrical pin 94 has a blind bore 102 with an internal thread on the end face, into which a fastening screw 104, designed here as a countersunk screw, for the tool W1 or W2 is screwed. Each tool W1 or W2 has several, in the illustrated embodiments four, screw holes 106 each, which are arranged on a line in the longitudinal direction of the respective tool W1 or W2 at equal distances from one another. Thus, the tool W1, W2 can be mounted on the further guide arrangement 88, more precisely its cylindrical pins 94, in a way that is adjustable in its axial position along the oscillation axis R, with the fastening screws 104 respectively passing through adjacent screw holes 106 in the respective tool W1 or W2.

[0071] This additional axial adjustment option for the tool W1 or W2 is in Fig. 9illustrated by way of example for the triangular tool W1. Starting from a basic configuration in which the tool W1 is mounted in a central position on the guide arrangement 88 by means of the fastening screws 104 extending through the central screw holes 106 of the tool W1, the tool W1 can thus be positioned further forward (in Fig. 9 shown in the middle) or further back (in Fig. 9 shown below) to the guide assembly 88. This results in - compared to the basic configuration according to the upper part of the Fig. 9 - an offset V1 or V2 at the front end EB of the tool W1.

[0072] Finally, the respective tool W1, W2 is subjected to a force in the direction transverse or perpendicular to the oscillation axis R of the tool carriage 26, which pushes the tool W1 or W2 away from the connecting part 80. In the illustrated embodiment, this force is applied by mutually repelling magnets 108 arranged between the connecting part 80 and the tool W1 or W2. During the actual polishing process, these magnets 108 ensure that the polishing pressure at the processing area BB of the respective tool W1, W2 is not excessive.

[0073] More precisely, the magnets 108 are arranged on the respective tool W1 or W2 on its side facing the tool carriage 26 between the screw holes 106 and in line with the screw holes 106, as shown in the Fig. 6 , 8 , 9 and 16 to 19can be seen. On the connecting part 80, a magnet 108 is arranged on the end face of the connecting part 80 facing the respective tool W1 or W2, between the cylinder bores 92 and in line with the cylinder bores 92, here on an insert 110 in the connecting part 80. In each case, the respective magnet 108 is received in an associated recess and suitably fastened, for example by means of an adhesive.

[0074] From the previous description it is clear that with the aid of the device 10 equipped with one of the tools W1, W2 and with the use of geometrically indeterminate cutting edges in the form of bound or loose grain in combination with a liquid on the machining area BB of the tool W1 or W2, a method for fine machining an axicon L can be carried out, in which method material removal is generated by means of the tool W1 or W2 on the conical surface KF of the axicon L by means of a relative cutting speed which is produced solely from a) a rotational movement of the axicon L about the conical axis KA - here brought about by the workpiece rotation axis D of the workpiece spindle 16 and b) a relative oscillating linear movement - here produced via the oscillation axis R of the device 10 - of the tool W1 or W2 which is in linear engagement LE with the conical surface KF to be machined.W2 results, in which the front end EB of the machining area BB, seen in a plan view, moves back and forth in the radial direction with respect to the cone axis KA.

[0075] This tool engagement under combined movements of tool and workpiece is in the Figs. 20 and 21 for the triangular tool W1 and in the Figs. 22 and 23 for the strip-shaped tool W2, in both cases using an axicon L with a concave conical surface KF. By using thicker lines, the Figs. 20 and 23the linear engagement LE of the respective tool W1 (here double, on both sides of the tool W1) or W2 (here single, on the underside of the tool W2) with the conical surface KF of the axicon L to be machined is illustrated. In the case of an axicon with a convex conical surface, the strip-shaped tool W2 with its lower tool contact line would be used, because the triangular tool W1 does not have a convex conical surface as in Fig. 20 shown to touch.

[0076] When carrying out the above-described method for fine machining an axicon L, a relative alignment and feed movement is first generated between the axicon L and the tool W1 or W2 in accordance with the cone angle α, as a result of which the machining area BB of the tool W1 or W2 enters into linear engagement LE with the conical surface KF of the axicon L, wherein the front end EB of the machining area BB faces the cone axis KA. It is apparent to those skilled in the art that the angular alignment movement with the above-described fine machining machine 12 takes place on the workpiece side by means of the pivot axis A on the yoke 36 supporting the workpiece spindle 16. It is also apparent that the spatial feed movement with the above-described fine machining machine 12 takes place on the tool side via the three linear axes X, Y, Z assigned to the tool spindle 14.

[0077] Once the linear engagement LE, defined by means of the magnets 108 on the connecting part 80 and the respective tool W1 or W2, has been established between the tool W1 or W2 and the conical surface KF of the axicon L to be finely machined, the relative oscillating linear movement (oscillation axis R) is generated as a feed movement between the axicon L, which is driven in rotation about the conical axis KA via the workpiece rotation axis D of the workpiece spindle 16, and the tool W1 or W2 by means of the tool spindle 14, the rotation disk 60 clamped thereto, and the gear mechanism 58 of the device 10, as described above, in which the front end EB of the machining area BB, seen in plan view, moves several times over the conical surface KF from an outer edge region RB of the conical surface KF in the radial direction with respect to the conical axis KA, at least close to the conical axis KA and back again. moved.

[0078] During the fine machining of the conical surface KF, the rotational speed of the axicon L about the conical axis KA and, by means of suitable speed control of the tool spindle 14, the frequency of the relative oscillating linear movement (oscillation axis R) of the tool W1 or W2 over the conical surface KF can then be coordinated via the workpiece spindle 16 in such a way that the number of back and forth movements of the tool W1 or W2 per revolution of the axicon L is not an even number. This results in a continuous "track change" of the oscillating tool W1 or W2 on the finely machined conical surface KF of the rotating axicon L. In tests carried out by the inventors, very good fine machining results were achieved with a frequency to speed ratio in which the number of back and forth movements of the tool W1 or W2 during the fine machining of the conical surface KFW2 per revolution of the axicon L around the cone axis KA was greater than or equal to 3 and less than or equal to 7.

[0079] In the manner described above, the Fig. 1 and 2 The fine machining machine 12 shown, which is already known per se, on whose tool spindle 14 the device 10 explained in detail above is mounted, can be used for the fine machining of an axicon L which has at least one concave or convex conical surface KF with a conical axis KA and a conical angle α.

[0080] In a method for fine machining an axicon having a concave or convex conical surface with a conical axis and a conical angle, using geometrically indeterminate cutting edges in the form of bound or loose grain in combination with a liquid, material removal is generated on the conical surface by a relative cutting speed in a machining area of ​​a tool which is designed for linear engagement with the conical surface and has a front end with respect to the conical axis. This cutting speed results solely from a rotary movement of the axicon about the conical axis and a relative oscillating linear movement (oscillation axis) of the tool, in which the machining area is in linear engagement with the conical surface and its front end, as seen in a plan view, moves back and forth in a radial direction with respect to the conical axis.Furthermore, a device which can be used for this method and which can be mounted on a tool spindle of a precision machining machine is disclosed. LIST OF REFERENCE SYMBOLS

[0081] 10 Fixture for fine machining of axicons 12 Fine machining machine 14 Tool spindle 16 Workpiece spindle 18 Working space 20 Machine bed 22 Base 24 Guide assembly 26 Tool slide 28 Side wall 30 Gantry 32 Horizontal slide 34 Vertical slide 36 Yoke 38 Counterweight 40 Chuck 42 Chuck 44 Hole 46 Mounting screw 48 Guide frame 50 Mounting bracket 52 Guide rail 54 V-shaped groove 56 Wedge-shaped guide section 58 Gear mechanism 60 Rotating disc 62 Clamping extension 64 Guide pin 66 Slot 68 Mounting hole 70 Mounting hole 72 Mounting hole 74 Threaded extension 76 Slot 78 Opening 80Connecting part 82Mounting hole 84Blind hole 86Set screw 88Guide assembly 90Guide cylinder 92Cylinder hole 94Cylinder pin 96Elongated hole 98Threaded hole 100Cap screw 102Blind hole 104Mounting screw 106Screw hole 108Magnet 110Insert r1radial distance r2radial distance r3radial distance xwidth direction ylength direction zheight direction αCone angle A Swivel axis of the workpiece (controlled by the angle of rotation) BB Machining area C Tool rotation axis (speed-controlled) / rotation axis D Workpiece rotation axis (controlled by the angle of rotation) EB Front end H1 Stroke H2 Stroke H3 Stroke KA Conical axis KF Conical surface LLens / Axicon LE Linear engagement RO Oscillation axis RB Edge area RF Edge surface V1 Offset V2 Offset V3 Offset V4 Offset V5 Offset V6 Offset W1 Triangular tool W2 Strip-shaped tool XLinear axis tool (position-controlled) Y Linear axis tool (position-controlled) Z Linear axis tool (position-controlled)

Claims

1. Method for fine-processing of an axicon (L), which has at least one concave or convex cone surface (KF) with a cone axis (KA) and a cone angle (α), by means of a tool (W1, W2) which has a processing region (BB) for linear engagement (LE) with the cone surface (KF) to be processed, the processing region having a front end (EB) with respect to the cone axis (KA), with use of geometrically indeterminate cutting edges in the form of bound or loose grain in combination with a liquid at the processing region (BB) of the tool (W1, W2), wherein material removal is produced by means of the tool (W1, W2) at the cone surface (KF) of the axicon (L) by a relative cutting speed resulting solely from a rotational movement (D) of the axicon (L) about the cone axis (KA) and a relative oscillating linear movement (oscillation axis R) of the tool (W1, W2) that in this case is disposed in linear engagement (LE) with the cone surface (KF) to be processed, in which the front end (EB) of the processing region (BB) as seen in a plan view moves back and forth in a direction radial with respect to the cone axis (KA).

2. Method for fine-processing of an axicon (L) according to claim 1, wherein initially a relative aligning and adjusting movement is produced between the axicon (L) and the tool (W1, W2) in accordance with the cone angle (α), as a consequence of which the processing region (BB) of the tool (W1, W2) comes into the linear engagement (LE) with the cone surface (KF) of the axicon (L), wherein the front end (EB) of the processing region (BB) faces the cone axis (KA), whereupon the relative oscillating linear movement (oscillation axis R) is produced between the axicon (L), which is driven to rotate about the cone axis (KA) (workpiece axis D of rotation), and the tool (W1, W2) as an advance movement in which the front end (EB) of the processing region (BB) during one revolution of the axicon (L) about the cone axis (KA) moves as seen in plan view multiple times over the cone surface (KF) in radial direction with respect to the cone axis (KA) from an outer edge region (RB) of the cone surface (KF) to at least the proximity of the cone axis (KA) and back again, and / or wherein during the fine-processing of the cone surface (KF) a rotational speed of the axicon (L) about the cone axis (KA) and a frequency of the relative oscillating linear movement (oscillation axis R) of the tool (W1, W2) over the cone surface (KF) are so matched to one another that the number of reciprocating movements of the tool (W1, W2) per revolution of the axicon (L) is an uneven number.

3. Method for fine-processing of an axicon (L) according to claim 2, wherein during the fine-processing of the cone surface (KF) the number of reciprocating movements of the tool (W1, W2) per revolution of the axicon (L) about the cone axis (KA) is greater than or equal to three and smaller than or equal to seven.

4. Device (10) for fine-processing of an axicon (L), which has at least one concave or convex cone surface (KF) with a cone axis (KA) and a cone angle (α), by a tool (W1, W2) having a processing region (BB) for linear engagement (LE) with the cone surface (KF) to be processed, comprising a base (22), which is adapted to be flange-mounted on a tool spindle (14) of a fine-processing machine (12), a guide arrangement (24) mounted on the base (22) and guiding a tool carriage (26), which is drivable for oscillation along an oscillation axis (R) and which carries the tool (W1, W2) for fine-processing of the axicon (L), to be longitudinally movable, a transmission mechanism (58), which adapted to convert a rotational movement produced by the tool spindle (14) into a reciprocating linear movement of the tool carriage (26) along the oscillation axis (R), and which comprises for this purpose a rotary disc (60), which is drivably connectable with the tool spindle (14) and is rotatable about an axis (C) of rotation and on which a guide pin (64) is mounted to be radially offset with respect to the axis (C) of rotation, the pin engaging in a slot (66, 76) which is formed to extend in the tool carriage (26) transversely to the oscillation axis (R) so that the tool carriage (26) is drivable to oscillate along the oscillation axis (R) with a predetermined stroke (H1, H2, H3), wherein the rotary disc (60) is provided with a plurality of securing bores (68, 70, 72) for the guide pin (64), the bores having a different radial spacing (r1, r2, r3) from the axis (C) of rotation so that the stroke (H1, H2, H3) of the tool carriage (26) is settable, and / or wherein the tool carriage (26) has at least two mutually parallely extending slots (66, 76) for selectable engagement of the guide pin (64), by way of which an axial relative position of the tool carriage (26) with respect to the axis (C) of rotation is settable.

5. Device (10) according to claim 4, wherein the guide arrangement (24) comprises a guide frame (48) on which guide rails (52) for the tool carriage (26) are mounted on mutually opposite sides.

6. Device (10) according to claim 5, wherein the guide rails (52) consist of a slide bearing material and have a respective V-shaped groove (54) on each of mutually facing sides, wherein the tool carriage (26) on each of mutually remote sides has a respective wedge-shaped guide section (56), and wherein the wedge-shaped guide sections (56) of the tool carriage (26) are received in the V-shaped grooves (54) of the guide rails (52) to be capable of sliding.

7. Device (10) according to any one of claims 4 to 6, wherein a connecting part (80) with a further guide arrangement (88) is mounted on the tool carriage (26) and serves for guiding the tool (W1, W2) to be movable in a direction transverse to the oscillation axis (R) of the tool carriage (26), and wherein the tool (W1, W2) is loaded in the direction transverse to the oscillation axis (R) of the tool carriage (26) by a force urging the tool (W1, W2) away from the connecting part (80).

8. Device (10) according to claim 7, wherein the force is supplied by at least two mutually repelling magnets (108) arranged between the connecting part (80) and the tool (W1, W2), and / or wherein the further guide arrangement (88) comprises at least one guide cylinder (90), and / or wherein the connecting part (80) is secured to the tool carriage (26) to be variable in its axial position along the oscillation axis (R), and / or wherein the tool (W1, W2) is mounted on the further guide arrangement (88) to be variable in its axial position along the oscillation axis (R).

9. Device (10) according to any one of claims 4 to 8, wherein the tool (W1) as seen in plan view has substantially the form of an isosceles triangle, with a processing region (BB) which has a front end (EB) at a tip of the triangle and which on each of mutually opposite longitudinal sides of the triangle allows for respective linear engagement (LE) with the cone surface (KF) to be processed of the axicon (L), or wherein the tool (W2) is substantially strip-shaped with a processing region (BB) which has a front end (EB) at a transverse side of the tool (W2) and which along a longitudinal side of the tool (W2) allows for linear engagement (LE) with the cone surface (KF) to be processed of the axicon (L).

10. Fine-processing machine (12), comprising a tool spindle (14) with a tool axis (C) of rotation and a workpiece spindle (16) with a workpiece axis (D) of rotation, which project into a work space (18) bounded by a machine bed (20) and which are movable relative to one another (Y axis, Z axis) at least in a notional plane (Y-Z) spanned by the tool axis (C) of rotation and the workpiece axis (D) of rotation as well as pivotable relative to one another with respect to a pivot axis (A axis) extending perpendicularly to the plane (Y-Z), wherein a device (10) for fine-processing of an axicon (L) according to any one of claims 4 to 9 is mounted on an end of the tool spindle (14) facing the workpiece spindle (16).

11. Fine-processing machine (12) according to claim 10, wherein the machine bed (20) has two side walls (28) between which the work space (18) is formed and which mount a portal (30), which is movable in a longitudinal direction (Y axis) and at which the tool spindle (14) is guided to be movable at least in a direction (Z axis) perpendicular to the longitudinal direction (Y axis), and wherein a yoke (36) is provided in the work space (18), which carries the workpiece spindle (16) and is mounted on the side walls (28) to be rotatable about the axis (A) of pivotation.

12. Use of a fine-processing machine (12) according to claim 10 or 11, on the tool spindle (14) of which a device (10) according to any one of claims 4 to 9 is mounted, for fine-processing of an axicon (L) having at least one concave or convex cone surface (KF) with a cone axis (KA) and a cone angle (α).