DE102020007626A1 - Clamping system with a base support plate, fixing unit for a clamping system and method for using a clamping system - Google Patents

Abstract

The invention relates to a clamping system with a base support plate and a carriage, which are arranged to be movable relative to one another in one plane, the base support plate and carriage being arranged to be movable relative to one another on two axes. In addition, the invention relates to a fixing unit and a rotary feedthrough for a clamping system and a method for using a clamping system.

Description

The present invention relates to a clamping system with a base support plate and a carriage, which are arranged to be movable relative to one another in one plane. The invention also relates to a fixing unit and a method for using the clamping system.

Such clamping systems are used in particular for the efficient production of lens arrays by machining. A lens array is a matrix-like combination of individual lenses that are machined or lasered into a coherent base body. The base body has a rotational symmetry about a reference axis for each lens. However, the individual lenses can also have non-rotationally symmetrical components around their reference axis, such as lenses with a rectangular edge or free-form lenses.

Lens arrays are becoming increasingly important for the production of optoelectronic structures, such as those found in consumer products, in sensor technology or in automotive engineering. Opto-electronic structures consist of electronic components, such as LEDs or sensors, and optical components, such as focusing lenses or diffractive lenses for imaging a pattern for sensory gesture recognition. These must be precisely assembled to each other to ensure the function.

The established standard in the production of electronic components is wafer-based semiconductor production. A large number of devices are fabricated simultaneously on a round wafer by exposure and etching processes. The individual units are located laterally on the wafer with tolerances of up to < 1 µm.

After the wafer has been produced, the units can be cut out of the wafer and, for example, assembled precisely to form an optic. The separation of the electronic components from the wafer and the subsequent assembly of individual assemblies are time-consuming and costly.

With a lens array in wafer form, so-called assembly can be carried out in the panel. Instead of assembling a single electronic unit into an optical unit, one assembles the complete wafer with electronic units into the lens array in wafer form, which has the same lateral distances between the lenses as the wafer. The wafer and the lens array are glued and fixed in a precise position relative to each other. The subsequent separation of the electronic unit and optics leads to finished functional units that do not require any further assembly steps. This approach significantly increases productivity during manufacture. A concrete example is the flashlight of a mobile phone, where an LED light source is mounted on a Fresnel optic and then built into the housing.

The production of such lens arrays poses great challenges in terms of production technology in order to ensure the quality of the individual lenses and the precision of the lateral position of the individual lenses in relation to one another. If the lateral positions of the individual lenses do not match, there will be rejects during assembly in the panel.

Lens arrays for assembly in panels are made replicatively with a tool. In addition to glass pressing, plastic injection molding and hot stamping of sheet material, the "Silicon on Glass" technology is preferably used. A metallic tool with the negative geometry of the lens array is filled with free-flowing silicone. Alternatively, optical varnishes (e.g. Ormocere) can be used. A wafer-shaped, thin, plane-parallel glass pane is applied to the wafer and silicon so that the silicon adheres to the glass pane. A process for curing the silicone is initiated. The glass pane together with the silicone optics is removed from the mold and serves as a finished optics unit, which can then be mounted in front of a wafer with electronic components.

The metallic molding tool is manufactured differently depending on the geometry of the optics and the material of the tool. The processes used for processing with the associated materials and the kinematics of the machine used must be differentiated.

Diamond turning with a geometrically defined cutting edge is the preferred process for manufacturing small individual optics in arrays. With diamond as the cutting material, optical surface qualities (dimensional stability < 0.5 µm, roughness < 3 nm Ra) can be produced directly with corresponding so-called ultra-precise machines. Machining using geometrically defined diamond cutting edges is limited to non-ferrous metals such as typically nickel-phosphorus coatings, brass and aluminium. In particular, steel tools with a nickel-phosphorus coating, which are machined using diamond tools, are suitable for the highest quality and productive replication in plastic. They can also be used for "Silicon on Glas".

High-strength tool materials for replicating glass (e.g. tungsten carbide) cannot be used process using a geometrically defined cutting edge. Grinding processes are used here to produce the individual lens geometries. Similar accuracies can be achieved, but the geometric degrees of freedom are limited when grinding compared to diamond turning.

The production of lens arrays by means of laser ablation (sublimation) is generally also possible and should be mentioned for the sake of completeness, however, comparable shape retention and surface roughness cannot yet be achieved with these processes. The use in precision optics is hardly given.

Regardless of whether it is turning or grinding, the common kinematics used to manufacture such lens arrays are referred to as “off-axis machining” (prior art, principle 1). Turning will be described in the further explanations as an exemplary process. An ultra-precision machine with three translational axes (X,Y,Z) and one rotary axis (C) (spindle with position control) is used here. The tool to be machined is clamped firmly on the rotary axis so that the axis of rotation of the spindle and the center of the wafer are exactly aligned. The kinematics for manufacturing the individual lenses on the wafer consists of 3 elements. The single lens in the center of the wafer can be manufactured conventionally by rotating the spindle (kinematic element 1) and interpolating movement of the translation axes X, Z with a tool along the single lens contour (kinematic element 2). For a single lens with a lateral offset to the center of rotation of the wafer, the spindle with the component (kinematic element 1) also rotates. The movement guidance of the tool along the geometry of the single lens (kinematic element 2) is now overlaid by the translation axes (X, Y) with another compensating movement (kinematic element 3), which compensates for the offset of the center of rotation of the single lens to the center of rotation of the wafer. To process any single lens in the wafer assembly with an eccentric lateral position to the middle of the wafer, the interpolating movement of the translation axes for tool guidance consists of the kinematic element 2 for creating the single lens geometry and the kinematic element 3 for compensating for the eccentric position. The further an individual lens is located from the center of rotation, the greater the stroke of the compensatory movement for compensation (kinematic element 3). Due to the combined kinematics of rotation and translation, the reversal points of the linear axis movements are in the optical surface to be cut. Reversal points are those points at which the linear axis completely changes its direction of movement.

In order to be able to guarantee maximum precision, the process speed must be greatly reduced in terms of the axis feeds of the interpolating axes. Otherwise, overshoots and resulting following errors (control engineering: deviation of the position setpoint from the actual position) will occur, particularly at the reversal points. These manifest themselves as defects on the optical surface of the workpiece to be cut.

The advantage of the production of microlens arrays with the approach of principle 1 is that a conventionally available ultra-precision machine can be used and only the programming for "off-axis processing" has to be supplemented. Disadvantages are the necessarily greatly reduced dynamics during processing and the resulting processing times for a lens array tool of up to one month and more.

the WO2017/036523 therefore describes a principle 2 to solve the efficiency problem of principle 1.

With an active clamping system, which is additionally applied to the main spindle of an ultra-precision machine (1), the kinematic approach can be changed compared to principle 1. The active clamping system ensures that each individual lens on the wafer is always positioned in the center of rotation of the main spindle, so that each individual lens on the wafer can always be processed "On Axis". This approach eliminates the need for a superimposed compensatory movement of the translation axes (X, Y) on the tool side (kinematic element 3). The tool-guiding, interpolating linear axes only have to be used to generate the individual lens geometry (kinematic element 2). This means that there are no reversal points in the traversing profile of the linear axes on the optical surface to be cut. Principle 2 enables significant increases in quality and efficiency.

In terms of construction, the task can be described in such an abstract way that the wafer with n individual lenses located eccentrically to the center of the wafer must be positioned laterally on the main spindle and clamped so that each individual lens is guided with its center of rotation into the center of rotation of the main spindle in order to "On Axis” to be able to edit.

the WO2017/036523 teaches the use of two additional rotary axes located stacked on the main spindle. Two degrees of freedom for lateral positioning are provided by rotation/rotation. The main spindle (rotation 1) has the task of turning to provide a single lens necessary cutting movement ready. A second axis of rotation is located on a base plate eccentrically to the axis of rotation of the main spindle. A third axis of rotation sits on top of this, again located eccentrically to the axis of rotation below. The wafer to be cut is fixed centrally on this third axis of rotation with a clamping system.

The wafer can now be positioned in a defined lateral area (polar kinematics) thanks to the two rotational axes that are eccentric to one another.

Due to the positioning of the wafer on the main spindle by means of two eccentrically offset axes of rotation, different mass distributions arise in relation to the rotation around the axis of the main spindle, depending on the positioning. During processing, these imbalances lead to disruptive forces that impair the quality of the individual lenses to be cut.

The advantage of in the WO2017/036523 The kinematic solution described with two eccentrically offset rotation axes is the possibility of solving the problem of the resulting imbalance through a constructively integrated balancing functionality. Eccentrically attached balancing masses are located on or at the eccentrically seated rotation axes, which counteract the displacement of the rotating masses during rotary positioning. Thus, constructive positioning and balancing can be combined.

From a process perspective, the wafer for processing an eccentrically seated single lens is positioned by two axes of rotation, each located eccentrically to the axis of rotation of the main spindle, in such a way that the axis of rotation of the single lens is exactly aligned with the axis of rotation of the main spindle. The balancing masses ensure that the mass distribution around the main axis of rotation is symmetrical and that no imbalances affect the main spindle during rotation. In this state, the rotary axes can be clamped individually to start machining.

Principle 1 according to the prior art is based on solving a necessary rotational correction movement by means of interpolating translational axes and thus being able to work "off axis" without re-clamping the wafer. This approach is not suitable for cutting high-quality lens arrays with high cost-effectiveness due to the high dynamics that inevitably arise in the reversal points of the axis movements.

Against this background, principle 2 introduces an active clamping system that can position the wafer to be processed on the main spindle in such a way that the respective individual lens is always located in the center of rotation of the main spindle and can therefore always be processed "on axis". A clever placement of additional masses can only prevent otherwise occurring asymmetrical distributions of masses by rotating the axes in the clamping system.

The kinematic solution according to the WO2017/036523 for the lateral positioning of the wafer on the rotating main spindle has three major disadvantages in the design implementation and in the application.

The precision of the main spindle rotation for turning is largely defined by its bearing. Such an air-bearing spindle usually has an axial bearing and two radial bearings to support the rotor. The bearing and rotor of the spindle are subject to tolerances, so that concentricity errors in the radial and axial directions can be detected by measurement. In a different way, the spindle rotor shows an angular offset (wobbling movement) and a residual eccentricity in its real rotation compared to an ideally assumed axis of symmetry. The eccentricity of the rotor movement has its minimum in the center of the wobbling movement, the further one defines a plane for considering the deviations from the center, the larger the total eccentricity becomes as a function of angular displacement and distance to the center. In the literature, this connection is described as Abbé's error.

By stacking two additional self-sufficient rotary axes with the respective height on the main spindle according to WO2017/036523 Inevitably, there are large distances to the internal bearings of the main spindle and thus noticeable Abbe errors at the cutting point between the tool and the workpiece (tool center point). This leads to errors in the optical functional surface of the single lens.

Furthermore, the axes of rotation are subject to weight, so that in the case of a horizontal structure, moments continue to load the bearings of the main spindle in addition to the purely geometric considerations. Here, too, the overall height of the construction is to be regarded as a disadvantage, since the constructive realization has a horizontal structure.

The requirements for lateral precision between two individual lenses are < 1 µm in order to correspond to the state of the art in classic wafer production. This accuracy can be at Principle 2 of the prior art can only be achieved by rotating two eccentric spindles. The individual lenses on a wafer are arranged in a classic checkerboard pattern. Their positions are defined in Cartesian terms (x, y) and tolerated. The position definition via eccentric axes takes place classically in polar coordinates (r, φ). The exact position of the center of rotation of the 3 rotation axes is necessary for the transformation from Cartesian to polar coordinates. The accuracy of the transformation is also influenced by the spindle bearing tolerances described above (radial and axial run-out errors).

In the WO2017/036523 roller bearings are used in order to be able to build more compactly. However, these have noticeably larger tolerances than the air bearings of the main spindle. Experience has shown that the determination of the individual centers of rotation with the necessary accuracy in the submicron range causes great difficulties in practice.

In the WO2017/036523 the necessary balancing for the respective positioning of individual lenses to the center of rotation of the main spindle is solved by cleverly positioned counterweights, which are moved along with the rotation of the eccentric axes. The functions of positioning the wafer and balancing the entire unit are firmly connected with one another in terms of design. An individual fine balancing or correction of one function in relation to the other cannot be solved automatically since no separate drive is provided, at most possibly by manual intervention. The balancing quality that can be achieved is therefore to be seen as a further principle-related disadvantage, since the lateral positioning of the wafer must always be given the higher priority.

It is therefore the object of the present invention to provide a new constructive solution for the production of lens arrays.

According to the invention, this object is achieved with a clamping system having the features of claim 1 . Deviating from known clamping systems, two rotary axes are not provided, but the base support plate and carriage are arranged to be movable relative to one another on two axes, which have at least one translatory axis. Integrated kinematics and a fixing unit are proposed for this clamping system. In terms of the method, the object is achieved by a method according to patent claim 11 . Advantageous developments of the invention are the subject matter of the dependent claims.

An axis is preferably a guide with drive and measuring system. These axes can each be connected to the base support plate and/or the carriage. A simple embodiment provides that both axes act on the moving base support plate. However, it is advantageous if at least one axis and preferably both axes are connected to the carriage via a coupling. When engaged, the clutch enables positioning and then enables the carriage to be released again.

The clamping system is located on a main spindle and can rotate. Axes are used to position the slide in defined positions on the axis of rotation of the main spindle.

The clamping system is mounted on a main spindle with an axis of rotation and is designed in such a way that it can align the respective centers of the axes of symmetry of the individual lenses precisely with the axis of rotation of the main spindle.

Preferably at least one axle and preferably both axles are connected to the carriage via a coupling. These axes can be located either on the rotating or on the stationary side with a coupling for docking.

Another positioning unit is used to compensate for imbalances on the main spindle that occur as a result of the lateral positioning of the base body.

The method for using the clamping system and in particular for producing a lens array provides that a base body is processed in a first step in such a way that all the centers of rotation axes are introduced into the surface and thus marked in order to define the lateral distances between the individual lenses with maximum precision .

Such marking can be implemented, for example, by diamond turning, milling or lasering. For example, if a single lens is to be rotated, the mark (rotational axis of the single lens) is aligned with the rotational axis of the main spindle. This is preferably done by pre-positioning using the clamping system, then a sensor located above the device detects the remaining eccentricity of the marking to the axis of rotation of the main spindle during a rotation of the base body on this. From the determined residual eccentricity, a corrective movement of the device can be determined algorithmically, by means of which the measured residual eccentricity can be iteratively optimized below a defined threshold value. If the threshold is undershot, the single lens geometry is through Rotation of the main spindle is introduced by turning or lasering. If the single lens is milled or ground, another rotation (powered tool) can be superimposed on the rotation of the main spindle.

The clamping system enables the lateral positioning of the center of rotation of a single lens of the lens array to the axis of rotation of the main spindle. It can be highly integrated and compact to minimize Abbe errors. Furthermore, it enables the balancing and positioning functions to be carried out separately and automatically in order to enable optimization of the two target variables independently of one another. An integrated low-distortion clamping can provide sufficient rigidity for machining after positioning and balancing. Additional measuring technology that is not integrated in the clamping system should enable the exact positioning movement in terms of quality assurance or provide a measured variable for iterative optimization.

• 1 den Aufbau eines aktiven Spannsystems mit Hauptspindel in der Seitenansicht,
• 2 das der Erfindung zugrundeliegende kinematische Grundprinzip,
• 3 ein mögliches Fixierkonzept für den Schlitten auf der Grundplatte,
• 4 die Anordnung der Translationsachse zur Positionierung des Schlittens und der Translationsachse zur Positionierung der Gegenmasse,
• 5 zeigt den Wafer vor Einbringung der Einzellinsen nach erfolgter Vorbearbeitung mit Referenzmarken,
• 6 zeigt den auszugsweisen Aufbau der Gesamtmaschine mit Hauptspindel, aktivem Spannsystem sowie einem Bearbeitungswerkzeug und einem Sensor zur Referenzmarkenerfassung und
• 7 zeigt den Ablauf des der Erfindung zugrunde liegenden Verfahrens.

The invention is explained in detail below with reference to the enclosed drawings. It shows

• 1 the structure of an active clamping system with main spindle in the side view,
• 2 the basic kinematic principle on which the invention is based,
• 3 a possible fixation concept for the slide on the base plate,
• 4 the arrangement of the translation axis for positioning the carriage and the translation axis for positioning the counterweight,
• 5 shows the wafer before insertion of the individual lenses after pre-processing with reference marks,
• 6 shows the excerpt of the structure of the entire machine with main spindle, active clamping system as well as a machining tool and a sensor for detecting the reference mark and
• 7 shows the sequence of the method on which the invention is based.

The clamping system 1 consists of a base support plate 2, which is fixed (e.g. screwed) on the rotor (not shown) of an ultra-precise spindle 3 with its rotation reference axis 4. The base support plate 2 is machined plane-parallel from both sides 5, 6 with the greatest accuracy (<1 μm flatness), so that a carriage 7 of the clamping system 1 can be moved laterally on it. The underside of the carriage 7 is also machined as a plane-parallel carriage plate 8 with high precision and the same accuracy requirements, so that when the carriage 7 and the base plate 2 are braced against one another, there are no deformations in the clamping system 1 and a high-precision, ideally contact-free process between the carriage 7 and the base plate 2 is enabled.

The movement or positioning of the carriage 7 in relation to the base plate 2 takes place in two degrees of freedom, each with two driven and position-controlled axes of translation 9 and rotation 10 in a plane 11. Miniaturized, high-precision axes with an integrated position measuring system (not shown) are used here , with which a higher-level position control can be set up. The possible increments of the drives (not shown) are selected such that they can move <100 nm increments, preferably <50 nm. For example, a piezo linear or rotary drive or an electromagnetic drive is used to drive the miniaturized axes. The integrated position measuring system is preferably optical.

The rotary drive is designed in such a way that it can rotate at least 360°, ideally however endlessly. The length of the linear drive is dimensioned such that it can position the center of the carriage, which is rotationally symmetrical in its basic form, over the center of the base support plate 2 or the axis of rotation 4 of the main spindle 3 in one end position. In the second end position of the linear axis, the outermost edge of the wafer must be moved up to the axis of rotation of the main spindle 1. The length of this travel of the translation axis 9 describes the radius of the wafer. It is advantageous to consider safety in the sense of additional travel in both end positions in the design. Due to the two degrees of freedom of the translation axis 9 and the rotation axis 10, every conceivable point on the wafer can be positioned exactly over the rotation axis of the main spindle 4.

Such positioning axes 9, 10 achieve the highest positioning accuracies, but do not have sufficient rigidity to absorb centrifugal forces during a subsequent rotation of the main spindle 4 with the base support plate 2 and slide 7. The fixing unit 12 prevents the carriage 7 from shifting relative to the set target position during processing. The constructive functions covered by the fixing unit 12 are the loosening and possibly lifting of the carriage 7 perpendicular to the plane 11 during the positioning routine and the low-offset and low-distortion fixing of the carriage 7 after positioning has taken place.

A preferred solution to the design problem lies in the 3 shown combination of permanent magnets 13 and an air bearing 14. Provided that the carriage 7 is magnetic, i.e. it has the property of being attracted by a magnet, these permanent magnets 13, which are incorporated in the base support plate 2, attract it to keep it during to fix the rotation. In order to release the carriage 7 from the fixation for the positioning and to be able to move it freely with ultra precision, the air bearing 14 is charged with compressed air.

The air bearing 14 is designed here by the parameters area and pressure in such a way that it lifts the carriage 7 against the acting magnetic forces. In this state, the carriage 7 floats on air bearings and is magnetically prestressed on the base support plate 5. The air bearing 14 required for this can be constructed, for example by using porous materials, so that it has a height of <10 mm. The magnets 13 are embedded in the base plate 2 so that they do not require any additional height. The Abbe error can thus be significantly reduced.

Alternatively, other structural solutions for the fixing unit 12 are conceivable. Instead of the magnetically prestressed air bearing 14, a combination of vacuum (fixing) and air bearing (lifting, positioning) could be used. Mechanical fixation would also be conceivable, for example by means of clamping claws (not shown) that can be actuated automatically. In addition to the actual function, safety during operation must be taken into account when choosing the constructive solution. An advantage of magnets 13 is that they fulfill the fixing function even without an active medium (e.g. vacuum) and thus prevent the carriage 7 from flying off during rotation.

The carriage 7 carries a structurally separate or integrated clamping unit 15 in order to fix a base body 16, such as the wafer described below, in a stationary manner for processing. The clamping unit 15 can function according to different operating principles, for example growing the wafer 16, mechanical clamping of the wafer 16 or clamping by vacuum is conceivable. If the wafer 16 is to be held by vacuum during the rotating processing, a rotary feedthrough 17 must be provided in the clamping system 1 to transmit the vacuum from the stationary side of the machine to the rotating side of the clamping system 1 . This rotary bushing 17 must also be able to compensate for the translational and rotational movements of the carriage 7 .

In addition to vacuum and compressed air, electrical signals must be transmitted from the rotating to the stationary side in order to be able to control the axis of translation 9 and the axis of rotation 10 . This is done by a rotary transmission 18 or a contacting station. While the rotary transmission 18 continuously keeps the electrical signals connected during the rotation of the base support plate 2, a contacting station would only transmit the signals during the positioning process, which takes place without rotation. The selection of the constructive solution depends on the selection of the drives and their control.

The rotating part of the clamping system 1 has no symmetry in the mass distribution around the axis of rotation 4 of the main spindle 1 . The mass distribution even changes depending on the positioning of the translation axis 9 and possibly also due to the rotation of the axis 10 due to a clamping of the wafer 16 that is not perfectly centered. Balancing is therefore a necessary basic function of the unit. The balancing function is divided into a manual step (one-off or to be carried out for recalibration) and an active step that should be carried out again and again during operation.

For the manual balancing step, threaded holes are attached to the circumference of the base plate 2 for correcting mass distribution, into which balancing weights 19 are introduced on the circumference, e.g. by screws. The system can be pre-balanced in the basic position (all units positioned centrally) by the mass of the screws or by the depth of screwing into the threaded hole (change in the radius of the mass). Since the mass of the clamping system is considerable, it is advantageous to carry out this balancing procedure not in relation to one level (base plate) but in two levels (back of the spindle with balancing weights 20. If balancing is only carried out in one level of the clamping system, it is not possible to clearly distinguish between a residual eccentricity and a wobbling movement of the rotor can be distinguished. For this type of balancing in two planes, acceleration sensors (not shown) should preferably be attached to the front and rear of the spindle. These sensors can be used to determine the remaining wobble of the rotor and the introduction of balancing weights 19, 20 minimize.

If the carriage 7 with the clamping unit 15 and the wafer 16 is moved out of the center position by the translation axis 9, a mass displacement occurs in relation to the rotation axis 10 of the main spindle 4. This displacement is compensated for by a second translation axis 21, which moves a counterweight 22. The correlation between the displacement position of the first translational axis 9 for positioning the wafer 16 and the translational axis 21 for positioning the counterweight 22 can be calculated for Calculate given mass ratios and set them in the sense of a control. Preferably, however, after the first translation axis 9 and the second translation axis 21 have been positioned according to a fixed ratio, the actually remaining imbalance is measured in order to carry out a corrective movement of the translation axis 21 to optimize the balance state with algorithm support. Such a measurement can be recorded using an acceleration sensor. If the main spindle 3 itself is guided in a linear axis, the determination of the following error of the linear axis can alternatively be used to assess the balancing quality. This procedure can be carried out automatically iteratively several times in order to achieve the best possible balance state. This active optimization function is of great added value, especially for processing in the edge area of the wafer with large eccentric mass displacements.

Lateral tolerances of <1 µm should be achieved for the positioning of the wafer. In the tolerance chain of the active clamping system 1 with absolute positioning accuracy are the traversing accuracies of the translation axis 9 and the rotation axis 10, the position and alignment of the axes to each other, the location of the clamping unit 15 and that of the wafer 16 after clamping to the carriage 7 as well as the position of the base plate 2 to the axis of rotation of the main spindle 3 to be considered. The effort involved in calibrating and aligning the entire unit would be immense in order to keep the total of this resulting tolerance chain <1 µm.

A combined procedure of pre-positioning with absolute accuracy of the clamping system 1 and subsequent measurement of the exact position and iterative correction is therefore described.

For this purpose, the wafer 16 to be processed is subjected to a marking process prior to the incorporation of lenses. The marking process has the sole task of introducing the centers of the individual lenses as reference marks 23, which are to be produced in the later processing step, in a laterally exact position, i.e. in an exact position parallel to plane 11, to one another on the surface of wafer 16 in such a way that they a sensor (21) can be detected in their position with submicron accuracy during the further course of the process. Diamond machining, laser engraving, printing or etching are suitable methods for marking. The introduction of such reference marks 23 with a lateral accuracy of <1 μm on a planar wafer surface corresponds to the prior art.

The wafer 16 prepared in this way with reference marks 23 is attached to the clamping system 1 with the clamping unit 15 . In order to cut a single lens with a reference mark 23 in full geometry, the slide 7 is positioned via the translation axis 9 and the rotation axis 10 in such a way that the reference mark 23 is above the rotation axis 4 of the main spindle 3 (pre-positioning with absolute accuracy of the clamping system 1).

The wafer 16 is now rotated (at least 360°, one revolution) and the sensor 24 monitors the residual movement of the reference mark 23 of the individual lens to be cut. The selection of the sensor 24 depends on the introduced reference mark 23. A camera with a high-resolution microscope objective is preferably used. If the reference mark 23 describes a circle with a radius R1 during the rotation about the axis of rotation 4 of the main spindle 3, the pre-positioning has a residual error. A correction positioning can be calculated algorithmically from the radius R1 and used to control the translation axis 9 and the rotation axis 10 . After the corrective positioning has been carried out, a new measurement is carried out in order to determine the optimized residual error with radius R2. This procedure can be repeated iteratively until a limit value (e.g. < 1 µm) is undershot. Only then does the tool 25 release the tool 25 for processing the individual lens with a complete geometry around the reference mark 23. Sensor 24 and tool 25 could be located axis-parallel on a portal 26 of an ultra-precision machine as a possible structural design.

The method on which this invention is based therefore describes a cascaded iterative procedure in order to first optimize the position of a reference mark 23 in relation to the axis of rotation 4 of the main spindle 3 and then the residual imbalance of the clamping system after positioning has taken place by correcting the tracking of the counterweight 22 using the second translation axis 21 to minimize. In the case of lower demands on positioning and balancing quality, the iterations can be dispensed with in the procedure described.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2017/036523 [0016]
• WO 2017036523 A [0019, 0022, 0026, 0028, 0031, 0032]

Claims (19)

Clamping system (1) with a base support plate (2) and a carriage (7), which are arranged to be movable relative to one another in a plane (11) and can be connected to one another in order to transmit a rotary movement from a main spindle to a workpiece fastened to the carriage, characterized characterized in that the base support plate (2) and carriage (7) are arranged to be movable relative to one another on two axes (7, 8) which have at least one translation axis (7) in order to position the carriage in relation to the main spindle. tensioning system claim 1 , characterized in that the two axes (7, 8) are an axis of translation (7) and an axis of rotation (8). tensioning system claim 1 or 2 , characterized in that at least one axis and preferably both axes are connected to the carriage via a coupling. Clamping system according to one of the preceding claims, characterized in that the base support plate (2) and carriage (7) are also arranged to be movable relative to one another perpendicularly to the plane (11). Clamping system according to one of the preceding claims, characterized in that it has a fixing unit (12) in order to move the base support plate (2) and carriage (7) apart and to fix them to one another. Clamping system according to one of the preceding claims, characterized in that it has a counterweight (22) which is arranged to be movable on a further axis (21). Fixing unit (12) for a clamping system (1) according to one of Claims 1 until 5 , characterized in that it has an air bearing (14) between the base support plate (2) and slide (7). fuser unit after claim 7 , characterized in that it has a magnetic fixation between the base support plate (2) and carriage (7). fuser unit after claim 7 or 8th , characterized in that it has a vacuum fixation between the base support plate (2) and carriage (7). Fusing unit according to one of Claims 7 until 9 , characterized in that it has a mechanical fixation between the base support plate (2) and carriage (7). Method for using a clamping system (1) according to one of Claims 1 until 6 , characterized in that a component (16) to be machined is provided in advance with reference marks (23) which precisely define the lateral position of optical elements to be manufactured later. procedure after claim 11 , characterized in that to manufacture a single lens on a component (16) with a reference mark (23), the reference mark (23) is positioned with the absolute accuracy of the clamping system (1) over the axis of rotation (4) of the main spindle (3), then a measurement is carried out with a sensor (24) to determine the residual eccentricity of the reference mark (23) to the axis of rotation (4) of the main spindle (3) and finally a corrective movement to be carried out is determined on the basis of the measured residual eccentricity. procedure after claim 12 , characterized in that the sensor (24) for determining the correction detects the previously introduced reference mark (23). Procedure according to one of Claims 12 or 13 , characterized in that the sensor (24) for determining the correction detects the actual actual positions of previously cut individual lenses. Procedure according to one of Claims 12 until 14 , characterized in that the positioning is carried out iteratively until a predefined accuracy is reached. Procedure according to one of Claims 12 until 15 , characterized in that after the carriage (7) has been positioned, a counterweight (22) is pre-positioned by means of a translation axis (21) in order to bring about a symmetrical mass distribution around the axis of rotation (4) of the main spindle (3). Procedure according to one of Claims 12 until 16 , characterized in that after the pre-positioning has taken place, a measurement is carried out by rotating the clamping system (1) in order to determine the actual residual imbalance and, supported by algorithms, to calculate a corrective positioning of the translation axis (21) with a counterweight (22). Procedure according to one of Claims 11 until 17 , characterized in that for fine balancing weights (19, 20) in two levels, the the base plate (2) and a second one on the back of the main spindle (3). Procedure according to one of Claims 11 until 18 , characterized in that the clamping system is balanced iteratively until a predefined accuracy is reached.

Images