Graduated and adaptive polishing tools, and method for the production thereof

Abstract

The invention relates to a polishing tool (1) for processing technical surfaces, consisting of a polishing main body (1a) and a polishing-means support (1b), wherein: the polishing-means support (1b) has at least one polishing grain; at least one material property of the polishing-means support (1b) changes perpendicularly or horizontally to an axis of rotation (3a) of the polishing tool in order to be able to control a polishing removal function in a targeted manner on a surface to be processed of a workpiece (2); the polishing tool comprises integrated cooling channels via which a polishing-means suspension is supplied; and the effect of the at least one polishing grain on the workpiece surface can be influenced by the change in the material property.

Description

title Graduated and adaptive polishing tools and processes for their manufacture Technical field of the invention

[0001] The invention relates to a polishing tool with adapted properties for the deterministic polishing of functional surfaces and to a method for producing a polishing tool.

[0002] Available polishing processes are often divided according to the geometry of the surface to be created. While a so-called shell tool with a large-area tool engagement is usually used for flat and spherically curved surfaces, sub-aperture tools must be used for aspherical surfaces and free-form geometries. For processes that use a large-area tool engagement, a so-called constant removal is aimed for, i.e. that a constant amount of material is removed at every point on the surface over the polishing time. If this is successful, very high dimensional accuracy and a reproducible polishing process can be achieved. Polishing processes that use sub-aperture tools place very high demands on the axis movement and the synchronization of the axes with one another, and the small-area tool engagement requires considerably longer polishing times.In addition, an increase in medium-frequency error influences, which experts refer to as so-called mid-spatial frequency errors, is unavoidable.

[0003] The increasing demands on the dimensional accuracy of optical surfaces with increasingly complex geometries require a deterministic polishing process with locally predefined removal functions. If this is successful, targeted shape correction can be achieved while simultaneously reducing surface roughness. For this reason, precise control of the required axial movements of the polishing tool is required. In practice, tool functions are determined using a spot lens, the required locally varying material removal rates are mathematically calculated, and the areas to be removed are specifically leveled using a dwell-time-controlled polishing process.

[0004] With the aforementioned large- and small-surface polishing tools based on mechanical-chemical removal, the design freedom of the polishing tool is limited. Traditionally, polishing bases are coated with polyurethane film or pitch. To increase this design freedom, various inventions and solutions have been disclosed in the prior art with the aim of being able to specifically influence polishing parameters. State of the art

[0005] The published patent application JPH1199452A presents a polishing tool in which the edge area of ​​the tool has a different hardness than the inner area. This tool uses an iron base body to which individual pads are applied. These pads differ in hardness and height depending on their position. The outer pads, which come into contact with the glass surface first, have a lower hardness (Brinell < 20) to prevent deep cracking caused by the pressure of the polishing tool.

[0006] A polishing tool for processing large wafers is described in JP2006231464A. The polishing tool consists of ring-shaped segments with different hardnesses to ensure a uniform polishing rate across the entire workpiece area. The hardness of the segments decreases from the center to the outside. The disclosed figures show a tool with a larger diameter and a smaller workpiece.

[0007] Likewise, a polishing process using differently arranged polishing pads is described in publication JP2006140240A. The tool is intended for chemo-mechanical polishing in semiconductor technology. The goal is to reduce negative effects such as detachment, peeling, and erosion of an insulating layer (low-k film, dielectric constant lower than SiO2, Σr < 3.9). For this purpose, the tool is coated with two different plastic pads that differ in their hardness. The overall surface is formed from the alternating arrangement of the individual pads. Although the hardness of the polishing tool can be changed for all of the pad arrangements presented, the arrangement of these pads is only possible discretely and is largely inflexible and unsuitable for a deterministic polishing process.

[0008] The patent JP5502542B2 describes a polishing pad that has adaptive It has a wide range of tool functions. This is intended to achieve consistent flatness while simultaneously avoiding polishing scratches. A base material is applied to the back of a urethane film using a wet coagulation process. The base material comprises two types of film elements with different Shore A hardnesses. The two types can be applied in various structures such as grids, rings, or stripes. With constant polishing pressure, different pressure forces are generated, allowing polishing particles to move more easily.

[0009] A complete tool for grinding and polishing is disclosed in document CN114473855A. The tool, designed as both a grinding and polishing tool, consists of two or more zones that differ in hardness in order to achieve different material removal rates at constant grinding / polishing pressure. Its use as a tool is suitable for flat surfaces for the chemical-mechanical polishing of semiconductor components. Likewise, document CN210139311 U presents a utility model for a polishing brush intended for use in glass polishing. The goal is to generate a uniform material removal rate across the entire surface by varying the removal rates of the individual zones. The tool is divided into an inner and outer circular ring zone, each of which contains a plurality of polishing zones with a base layer and a polishing layer.The hardness of the polishing layer in the inner area is chosen to be lower than in the outer area.

[0010] The use of adaptive polishing tools, however, has also been described for the application of asphere polishing and is the subject of current research. For example, the dissertation (Scheibe 2016 - Scheibe, H.: Active-adaptive polishing tools for producing rotationally symmetrical aspheres. Dissertation, TU Ilmenau. 2016) presents a method for polishing aspheres using a full-surface active-adaptive polishing tool. The tool consists of a combination of an adaptive part and an active part. Both are arranged in a serial manner. The full-aperture contact zone between the tool and the workpiece is achieved by actively deforming the basic shape of the tool. A special needle array is proposed for the targeted sequential deformation of the tool. Although all solutions disclosed in the prior art describe various solutions for variable hardness values ​​of polishing tools and adaptive functionalities of their design, these are very limited in the gradability and flexibility of the polishing tool functions and for deterministic polishing. Description of the invention

[0011] It is therefore the object of the invention to provide a polishing tool for deterministic polishing whose functionality flexibly enables a specifically adjustable polishing removal rate at any point on the tool and, moreover, enables this functionality throughout the entire processing area, thus enabling the targeted processing of aspheres and complex-shaped components, in particular freeform surfaces. Furthermore, the object of the invention is to provide a method for producing a tool for graduated and adaptive polishing.

[0012] The problem is solved by the subject matter of the main claim. Advantageous embodiments are specified in the subclaims. The polishing tool is formed by a polishing base body and a graduated polishing agent carrier. The polishing base body can be made of steel, aluminum, hard metal, or composite materials and plastics, depending on the requirements of the polishing task. The polishing agent carrier is made of a plastic, for example polyurethane, polyamide, or light-curing materials such as acrylates and epoxy resins. The polishing agent carrier is preferably adapted rotationally symmetrically or specifically in the X and Y dimensions in its polishing function with graduated adjustments. The polishing function results from the material removal from the workpiece over a selected polishing time.The aim of the invention is to provide different zones of the polishing agent carrier, which produce a different material removal on the differently curved workpiece surface(s). In a simple embodiment of the invention, a polishing agent carrier with two zones is provided for a rotationally symmetrical polishing tool. While the first zone in the center and surrounding area has a high hardness, for example Shore hardness D 83, and the second zone in the outer area and the edge area of ​​the polishing agent carrier has a lower hardness, for example a Shore hardness D of 75, a defined, different material removal can take place on the workpiece surface. This difference in the removal function and the resulting material removal can be advantageous for. Can be used for machining workpieces on multiple support bodies. If, for example, there is a workpiece in the center of a multiple support body and other workpieces, say three, distributed at a distance from the center on a radius, then different stock removal conditions arise during polishing due to the different peripheral speeds of the workpieces. Experience has shown that the workpieces located in the edge area are removed more rapidly than the workpiece arranged in the center of the support body due to the higher rotational speed and resulting cutting speed. Preferably, the hardness of the polishing agent carrier is specifically designed for the two zones, depending on the different stock removal functions.Advantageously, the zones with different required polishing properties can have not only two, but also a large number of different zones, so that the required removal profile can be better approximated when polishing surfaces.

[0013] If the graduation, i.e., the number of different polishing agent carrier zones of the polishing functions, is selected very high, then the removal function approaches a continuous transition from a maximum to a minimum hardness value across the selected diameter of the polishing tool. Such continuous transitions are also advantageously provided in an XY planar extension of the polishing agent carrier, whereby a different progression can be selected in the X extension than in the Y direction. For example, a continuous transition in Shore D hardness from 52 - 77 can be selected in the X extension of the polishing agent carrier, and a continuous transition in Shore D hardness from 75 - 80 can be selected in the Y extension.This different design of the polishing functions in the X and Y directions of the polishing tool allows the removal functions to be specifically adapted for off-axis workpieces, highly curved surfaces, cylindrical lenses and mirrors, as well as freeform optical components, in order to achieve constant removal and a deterministic polishing process. The use of a continuously changing hardness profile of the polishing agent carrier can be advantageously used for changing cutting speed conditions. If the rotational axes of the workpiece and polishing tool coincide, the cutting or rotational speed of the polishing tool changes from the center to the edge of the workpiece. This change can be transferred into a polishing function using a mathematical calculation.The polishing function represents the integral progression from the center of the workpiece, where the (theoretical) cutting speed is zero, to the edge of the workpiece, where the. Cutting speed is maximum. With knowledge of the friction coefficient of the polishing agent carrier material used, this polishing function can be transferred into a gradation distribution function of the polishing agent carrier. With sufficiently accurate estimation of the Preston coefficient and adjustment of the continuous hardness profile of the polishing agent carrier, a constant removal rate can be achieved over the entire surface to be polished. For a polishing area of ​​100 cm 2 and the workpiece made of Boron glass BK7, the PRESTON coefficient C p = 10 -7 cm 2 N -1A normal force of N = 10 N and a polyurethane polishing agent carrier are assumed. The experimentally determined coefficient of friction is 0.622. These continuously changing polishing functions are particularly advantageous for large-area workpieces, such as telescope mirrors, wafers for the semiconductor industry, and cylindrical optics.

[0014] It is advantageous to also vary the hardness curve in the vertical direction. By adjusting the hardness curve in the horizontal and vertical direction of the polishing agent carrier, the resulting polishing function can be specifically influenced. The gradation of the hardness curve in the vertical direction enables the damping function of the polishing agent carrier to be set for the polishing grain in its effect on the workpiece surface, which generally follows a spring damping model. If, for example, the restoring force of the polishing grain in the interaction zone is low and the polishing agent carrier has high damping, little material is removed at this point on the workpiece surface. In the opposite case, when the damping of the polishing grain by the polishing agent carrier is very low, a higher material removal can be recorded at this point. Furthermore, the temporal polishing function can be changed by varying the hardness curve in the Z direction.This time-variable polishing function results from the wear and removal of the polishing agent carrier in the Z direction. Depending on the wear and polishing time, different hardness profiles can be created by varying the hardness curve in the Z direction. In classic polishing processes, a polishing tool is usually constructed in such a way that a very rigid tool base body, in steel or cast iron, embodies the negative form to be polished and a polishing agent carrier fulfils the damping function, usually made of polyurethane film or pitch. A defined transition from hard to soft is therefore predetermined and cannot be influenced. Preferably, however, a variation of the transition between the polishing base body and the polishing agent carrier is provided. For this purpose, the base body and the polishing agent carrier can advantageously be joined to form a tool or can also be manufactured monolithically. The gradient extends over a larger area in the Z direction. This makes it possible to design the spring damping model for the polishing process by specifically varying the hardness and stiffness across the Z extension of the tool and to adapt it zonally for the corresponding polishing functions. This allows for a deterministic polishing process with high reproducibility.

[0015] A particular advantage of the graduated and adaptive polishing tool is the standardization of the polishing base body. For conventional polishing processes, polishing base bodies must be provided for each radius to be polished. Due to the wide variety of radii of the spherical lenses and mirrors used in optical systems and assemblies, a large number of different polishing base bodies must be kept on hand or manufactured. Thanks to the adaptive function of the proposed polishing agent carrier, this large number can be reduced to a few polishing tools. This is achieved by directly introducing or manufacturing the required radius during the manufacture of the polishing agent carrier. Thus, the polishing base bodies can be designed as simple flat tools to which the polishing agent carriers are cemented.If the accuracy of the required radius is insufficient, the polishing tool is dressed with a diamond tool during the polishing process. It is also possible to dress the polishing tool to a different radius, so that different radii can be produced with one polishing tool. This requires that the polishing agent carrier has a certain center thickness in order to be able to dress it multiple times. Furthermore, it is planned to provide the polishing agent carrier as a full-aperture negative mold for aspheric polishing. For this purpose, the aspheric mold is also additively introduced into the polishing agent carrier, based on the mathematical asphere equation. The accuracy of the polishing tool can be further increased by a dressing step in the polishing machine. A special embodiment of the invention provides for the use of the polishing tools for the full-aperture polishing of free-form optical components.Due to the discontinuous surface transitions in freeform optics, polishing in the kinematic arrangement typical for rotationally symmetric components is not possible. It is advantageous to create a negative mold of the freeform surface to be polished as a polishing agent carrier. In this case, the active energy of the polishing grains is transferred during the polishing process not through a rotational movement of the polishing tool and the workpiece, but rather through a translational vibration force between the polishing tool and the workpiece. By varying the amplitude and frequency of this periodic oscillation, the material removal can be further optimized. Depending on the size and shape of the workpiece to be machined, the amplitude can range up to several micrometers and the frequency from a few hundred Hz to the ultrasonic frequency of 60 MHz.

[0016] The graduated and adaptive polishing tools are particularly advantageous for polishing with constant removal and deterministic polishing. The invention is also suitable for the targeted corrective polishing of components. For this purpose, after the polishing process, the surface is measured, for example, interferometrically, and the zonally corrected defects are analyzed. Based on this topographical defect representation across the entire surface or across individual sub-areas of the workpiece surface, a further polishing function is calculated and converted into a hardness profile function. Based on this analytical evaluation, a further polishing agent carrier is produced that can specifically eliminate the local defects.In the implementation of the graduated polishing agent carrier, this means that in the zones of the workpiece surface where material still needs to be removed, this area of ​​the additional polishing agent carrier is provided with a higher hardness. In the area of ​​the workpiece surface where little or no material is to be removed, the area of ​​the additional polishing agent carrier is provided with a lower hardness, or the additional polishing agent carrier is left omitted. In addition, areas of the additional polishing agent carrier can be provided without material, so that no material is removed in these areas.

[0017] The use of graduated and adaptive polishing tools is ideal for silicate materials, especially glass and ceramics, plastics and composite materials, metals, especially steel, aluminum, copper, and hard metals, as well as crystals such as silicon, germanium, zinc selenide, calcium fluoride, and sapphire. The range of required hardness values ​​of the polishing media carriers is adapted depending on the material-specific grinding or polishing hardness of the workpieces. The type and size of the polishing media used are also taken into account when designing the respective polishing tool. For example, cerium oxide is used as a polishing agent for glass and ceramics, while aluminum oxide is used for plastics and composite materials. Diamond grit is also used for polishing materials with particularly high hardness.Typical grain sizes for polishing with graduated and adaptive polishing tools range from 1 pm and smaller in average grain diameter. Nanoscale polishing suspensions can also be used.

[0018] . Cooling channels for supplying the polishing suspension and for removing the removed workpiece material and the worn polishing grit are advantageously incorporated in the polishing tool. These cooling channels can be designed in a lateral orientation of the polishing agent carrier, i.e. perpendicular to a rotation axis of the polishing tool, or in a vertical direction, i.e. parallel to a rotation axis of the polishing tool. A characteristic of both cooling channel arrangements is that they can be used very flexibly and with a great deal of design freedom. Typically, structure widths of 10 μm to 5 mm are selected for the cooling channels in a lateral orientation, depending on the component size and shape. This means that micro-optical and micromechanical components can also be processed using the solution according to the invention. With a structure width of the lateral cooling channel of 10 μm, microlenses with a minimum diameter of 0.3 mm, for example, can be polished.The lateral cooling channels can be designed with a structure depth of 100 pm up to the maximum polishing agent carrier thickness or can also change their structure width in a defined manner in the Z direction. This application is particularly advantageous if the polishing agent carrier is to be used multiple times and must be dressed for variable workpiece geometries. The vertical cooling channels in the polishing base body and polishing agent carrier serve to supply the polishing agent suspension in a targeted manner. In particular for large-area polishing tools, this ensures a constant, evenly distributed polishing agent flow over the entire area of ​​the workpiece surface. Furthermore, the invention provides a solution for designing the cooling channels in such a way that they transport or apply a defined pressure to the polishing agent carrier and the workpiece surface over their path length and the channel diameter.By deliberately varying the size and shape of the cooling channels across the entire polishing tool surface, different polishing pressures can be applied to different areas of the workpiece surface. This application is particularly suitable for polishing with variable cutting speeds and corrective polishing.

[0019] The object is further achieved by a method for producing the polishing tool. Advantageously, a method for layer-by-layer application of the polishing agent carrier is used. A printing process is used that can dose liquid polymer onto a platform via two print heads. In a print head for component A 16a, the polymer with lower Shore hardness, component A, is stored, and in a print head for component B 16b, the polymer with higher Shore hardness, component B, is stored. Components A and B can be made from a polymer with different hardnesses, for example acrylate, Shore D 75 - 83 or even with two different polymers. During layer-by-layer printing, both components can be applied sequentially or in parallel. The availability of a mixing unit allows component A and component B to be mixed in any desired ratio. This means that using an additional print head for components A and B, 16c polymers with variable percentages of component A and component B in each layer can be printed, even in varying amounts. After each layer has been applied, the layers are cured using a UV radiation source. Typical layer thicknesses range from 50 pm to 200 pm. If the component is dressed again after additive manufacturing, larger layer thicknesses can also be selected. The maximum printing range in the X and Y directions of the polishing tools is typically 600 mm x 600 mm. For larger polishing tools, the printing range can be expanded by scaling the X and Y axes of the printing system.

[0020] By using a support material, it is possible to designate areas of the polishing agent carrier during printing where no material should be available after the tool has been completed. This particularly applies to the cooling channels or zones in the polishing tool that should not cause material removal from the component. The support material used is, for example, a water-soluble polymer and is dosed into the layer to be printed via a print head for the support material 16d. This print head for the support material 16d can also work sequentially or in parallel with the other material print buttons. After the polishing agent carrier or polishing tool has been completed, the support material is removed from the 3D printed body in a cleaning step.The arrangement and selection of the cooling channel geometry can be designed so that the polishing agent streams are directed in a targeted manner inside the polishing tool, additionally creating a different pressure distribution across the surface to be polished. For example, if higher polishing pressures are achieved in the inner area of ​​the polishing tool, the center of the component can be removed more than the edge areas. The ability to apply different materials and material properties in layers provides the prerequisite for producing polishing tools entirely in a single printing process. While the polishing base body is printed from a harder polymer to achieve high rigidity, the polishing agent carrier A lower hardness is selected. Furthermore, a targeted gradation of hardness can be provided from layer to layer. The monolithic composite of the polishing base and polishing agent carrier allows the introduction of continuous cooling channels. This allows the polishing suspension to be fed directly within the tool into the active zone between the polishing agent carrier and the component surface. The layered structure allows for the flexible and customized creation of very different geometries. In addition to flat polishing tools, negative molds for spherical, aspherical, and freeform surfaces can also be additively manufactured.

[0021] For polishing tasks with high demands on dimensional accuracy, additional dressing of the polishing agent carrier can be provided after the printing process. For this purpose, the polishing agent carriers are cemented to the base body and then further processed with a dressing tool, for example a diamond-bonded tool. Dressing can be carried out on a path-controlled CNC machine or directly in the polishing machine in which the polishing tool is mounted. Through repeated dressing, worn polishing agent carriers can be reconditioned after the polishing process. If polishing agent carriers with larger center thicknesses are kept in stock, they can also be used for different polishing tasks. By dressing again, radii and other surface geometries, for example, can be varied.

[0022] The invention is explained in more detail below using exemplary embodiments with reference to the attached drawings, which also disclose features essential to the invention. These exemplary embodiments are for illustrative purposes only and are not to be interpreted as restrictive. For example, a description of an embodiment with a large number of elements or components should not be interpreted to mean that all of these elements or components are necessary for implementation. Rather, other embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with one another unless otherwise stated. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. Short description of the drawings They show:

[0023] Fig. 1 a the arrangement of the polishing tool with two zones for polishing several spherical components on a multiple support body Fig.1 b the polishing tool with two zones in the sectional view,

[0024] Fig. 2 a multi-zone tool for deterministic polishing of flat workpieces,

[0025] Fig. 3a is a plan view of a rotationally symmetrical polishing agent carrier having three zones of different hardness, Fig. 3b is a plan view of a square polishing agent carrier with a hardness profile varying in the X and Y directions, Fig.3c a section through a polishing agent carrier with changing hardness profile in Z direction,

[0026] Fig. 4a a plan view of a rotationally symmetrical polishing agent carrier with horizontally arranged cooling channel structures, Fig. 4b a section through the polishing tool with polishing base body and polishing agent carrier as well as the arrangement of a vertically distributed cooling channel structure,

[0027] Fig. 5a the sectional view of the polishing arrangement of a rotationally symmetric asphere with full-aperture polishing tool, Fig. 5b shows the sectional view of the polishing arrangement of a rotationally symmetric asphere with a two-part graduated sub-aperture polishing tool for sequential pre- and fine polishing,

[0028] Fig. 6 the sectional view of the polishing arrangement of a freeform geometry with full-aperture polishing tool and several zonal polishing functions,

[0029] Fig. 7a Illustration of the arrangement for printing the graduated polishing agent carriers or polishing tools with two print heads for component A and B, and Fig. 7b Illustration of the arrangement for printing the congratulated polishing agent carriers or polishing tools with two print heads for the material mix of component A and component B as well as for the support material. Detailed description of the drawings

[0030] A first embodiment is shown in Fig. 1a and 1b. The arrangement shows a polishing tool 1 below with two different hardness zones 11.a and 11.b. This is used to polish twelve convex lenses on a multiple support body. A first lens 2a and a second lens 2b are arranged at two different distances from a rotation axis 3b of the workpiece carrier 22. Due to the different peripheral speeds, the cutting speed for the first lens 2a is lower than that for the second lens 2b. This leads to the second lens 2b experiencing a higher material removal than the first lens 2a. This different material removal can be compensated for with the selected zone division of the polishing agent carrier 1b, which corresponds to the geometric arrangement of the lenses. Accordingly, the zone 11.a with a higher hardness and higher friction coefficients than zone 11 b and additively manufactured.

[0031] Fig. 2 shows a further exemplary embodiment for the machining of flat components. The polishing tool 1 is formed by a base body 1a and a multi-zone polishing agent carrier 1b. In this polishing arrangement, the axis of rotation of the workpiece 3b is shifted by the radius of the workpiece 2 from the axis of rotation of the polishing tool 3a. Zone 11a is provided with a maximum hardness of 82.5 Shore D, with zone 11b having the minimum hardness value of 71.5 Shore D. Further zones are provided between the two zones, with a continuous transition. The selected continuous change in the coefficient of friction is proportional to the changing cutting speed profile. This ensures constant material removal over the entire surface of the component.

[0032] Selected polishing agent carrier arrangements are illustrated in Fig. 3a-c. The three exemplary representations represent only the basic hardness profiles, whereby the design diversity of the process used can significantly increase the number of zones. Furthermore, the selected printing process is capable of graduating the hardness profile with a continuous transition from a maximum to approximate the selected value to a minimum value. Fig. 3a shows a plan view of a rotationally symmetrical polishing agent carrier 1 b which has three zones of different hardness. With the three selected zones 11 a, 11 b and 11c, a hardness gradient, hard to soft, occurs from the center of the polishing agent carrier 1 b outwards. If the surface to be polished has an edge support after the pre-processing stages, i.e. the edge has to be removed more, the hardness gradient can also be selected in the other direction. Fig. 3b shows a plan view of a square polishing agent carrier 1 b with a hardness gradient that changes in the X and Y directions. This arrangement illustrates the possibility of selecting a zonal gradient for the resulting polishing function. As an example, the same hardness gradients were selected in the X and Y directions.The inventive solution also allows a different selection of the hardness profile in the two axial directions. The number of adjustable zones can be selected as small as desired, within the resolution limits of the printing process. This is typically 160 dpi. This zonal division represents a possible polishing tool arrangement for cylindrical surfaces and free-form surfaces. Fig. 3c shows a section through a polishing agent carrier 1b with a changing hardness profile in the Z direction. Depending on the layer sequence, a hardness profile or a targeted change in the hardness can occur in each layer in the Z direction. The limitation of the zonal resolution is the layer thickness. Typical layer thicknesses for the additive process are in the range of 50 to 200 μm. A simultaneous combination of the hardness functions in the X, Y and Z directions allows the defined change of the polishing pressure 21 in zonal regions of the polishing tool surface.

[0033] The introduction of defined cooling channels is illustrated by way of example in Figs. 4a-b. In principle, two arrangements of cooling channel structures are possible. Fig. 4a shows the possibility of introducing cooling channels that can be distributed over the entire surface of the polishing agent carrier 1b or only introduced zonally. In general, the cooling channels close to the surface ensure the uniform distribution of the polishing suspension and the removal of the removed glass residues. In this case, linear cooling channel structures 7a, concentric cooling channel structures 7b, or free-form cooling channel structures 7c are introduced using the additive process. The distribution of the channel structures over the polishing tool surface can also be irregularly selected, however, in the case of zonal polishing, when constant removal of material is not desired on the surface. The channel depth is between 1 - 5 mm, but can also be designed to cover the entire depth of the polishing agent carrier if the polishing agent carrier 1 b is used multiple times or if the polishing suspension is passed on inside the polishing tool 1 , as shown in Fig. 4b. In this arrangement, the polishing suspension is fed into the tool and is passed via the base body into the polishing agent carrier 1 b. By selecting the cooling channel size, in particular the selected diameter and the number of cooling channel outlets on the tool carrier, the polishing pressure 21 on the polishing grain can be specifically adjusted. In this arrangement, too, different polishing pressure values ​​can be generated zonally on the polishing tool surface. In Fig. 4b, the number of integrated cooling channels in the center of the tool is higher than in the edge area.This increase in polishing pressure in the center of the polishing tool 1 can be advantageously used for polishing when the rotation axis of the polishing tool 3a coincides with the rotation axis of the workpiece 3b. A combination of the arrangement examples from Fig. 4a with those from Fig. 4b is also possible, opening up a high degree of design freedom for deterministic polishing.

[0034] Figs. 5a and 5b illustrate two possible arrangements for the deterministic polishing of aspheres. In Fig. 5a, the polishing tool 1 was designed for full-aperture polishing. The inverse asphere equation of the asphere shape to be polished was used as the target geometry for the additive process. After printing, the polishing agent carrier 1b is cemented or bonded to the base body and dressed in the polishing machine with a diamond tool. Three zonal regions 11a, 11b, and 11c were selected for the course of the polishing function, which are adapted to the change in the sagittal height and the distance from the tool center. In addition, an edge support 12 is provided to counteract edge bevel. This eliminates the need for complex support ring arrangements on the asphere blank, as required for conventional asphere polishing. This arrangement shown is particularly suitable for asphere pre-polishing.Even after aspheric fine polishing, an additional polishing step with the arrangement in Fig. 5a can follow in order to minimize any medium-frequency error components that arise. The polishing time for this intermediate step is selected to be very short in order to avoid deviations from the target shape. Fig. 5b illustrates aspheric polishing with a graduated and adaptive sub-aperture polishing tool 1. The polishing agent carrier 1b is divided into two zones 11a and 11b. A characteristic feature of this arrangement is that zone 11a has a larger diameter and a greater depth. This part of the polishing tool 1 is used for pre-polishing. After corresponding wear of zone 11a, the depths of the two zones approach each other. The second zone 11b is then used for. Fine polishing is used. If wear is not sufficiently high over the polishing period, the polishing tool 1 can be dressed to the required target depth. In the arrangement shown in Fig. 5b, the subaperture polishing tool 1 can also be guided in a meandering motion over the surface, allowing the machining of aspheres without rotational symmetry and free-form shapes.

[0035] The arrangement shown in Fig. 6 is suitable for polishing freeform surfaces. This exemplary freeform workpiece, simply selected as an example, has a square base area of ​​50 mm x 50 mm and a maximum component height of 40 mm. In this example, too, the required negative polishing form was additively manufactured as polishing tool 1. Depending on the changing sagittal angle of the freeform, different hardness zones were assigned. In total, the tool is supported by six differently loaded zones. For larger sagittal angles, the harder zone 11a is assigned, and for smaller sagittal angles, zone 11b. Depending on the freeform function, this exemplary assignment can also require a significantly larger number of different zones that can be assigned to the additive process.The transfer of the required active energy to the polishing grains, which are located in a suspension in the active gap 13 and are not shown in the figure for reasons of clarity, occurs in this arrangement through a vibration component that acts perpendicularly on the polishing tool 1. In this way, the polishing grain receives its energy in order to release the required activation potential on the workpiece surface. This required vibration energy can be provided, for example, by an ultrasonic generator coupled to a synotrode, or by two oscillators that create an imbalance and generate a vibrating force component 14. By controlling the amplitude and frequency of the oscillating movement, the polishing pressure 21, the coefficient of friction and the grain movement in the active gap 13 can be adjusted. The resulting spring-damping model can thus be specifically adjusted through the selection and graduation of the polishing agent carrier 1b.

[0036] Fig. 7a and Fig. 7b each show an exemplary example of the process for producing the graduated and adaptive polishing tools 1. In Fig. 7a, two pressure systems 16a and 16b are used, which can dose and apply very small amounts of liquid polymer. These pressure systems store two different components, in this case, component A with the higher hardness and component B with the lower hardness. Both pressure systems can work sequentially or in parallel and apply the respective required pressure volume per Layer. After successful layer generation, the build platform 15 lowers and the subsequent layer is created. To provide material properties that require a continuous transition of parameters, the printing system in Fig. 4b is used. Using a mixing system 19, the starting components A and B, stored in containers 18a and 18b, can be mixed at different volume percentages. This prepared mixture can be metered and applied using the print head for components A+B 16c. In addition, Fig. 7b shows another print head for the support material 16d. From this, a support material is metered and applied, which can be removed again after the build process. Water-soluble polymers are advantageously used as the support material. This introduction of the support material is necessary to provide the necessary cooling channels 8 in the polishing tool 1.After each layer is created, the polymer is UV-cured using a UV radiation source 20. List of reference symbols 1 - Polishing tool 1a - Polishing base body 1b - Polishing agent carrier 2 - Workpiece 2a - first lens 2b - second lens 3a - Rotary axe (polishing tool) 3b - Rotation axis (workpiece) 7a - Cooling channel (linear) 7b - Cooling channel (concentric) 7c - Cooling channel (freeform) 8 - Cooling channel (vertical) 9a - Zone of higher hardness - translational, horizontal 9b - Zone of medium hardness - translational, horizontal 9c - Zone of lower hardness - translational, horizontal 10a - Zone of higher hardness - translational, vertical 10b - Zone of medium hardness - translational, vertical 10c - Zone of lower hardness - translational, vertical 11 a - Zone of higher hardness - radial 11 b - Zone of medium hardness - radial 11c - Zone of lower hardness - radial 12 - Edge support 13 - Effective gap 14 - translational periodic force component 15 - Construction platform 16a - Print head for component A 16b - Print head for component B 16c - Print head for components A+B 16d - Print head for the support material 17 - printed layers 18a - Container Component A b Container Component B Mixing unit UV radiation source Polishing pressure Workpiece carrier

Claims

Patent claims 1. Polishing tool (1) for processing technical surfaces, consisting of a polishing base body (1 a) and a polishing agent carrier (1 b), wherein - the polishing agent carrier (1 b) has at least one polishing grain, - at least one material property of the polishing agent carrier (1 b) changes vertically or horizontally to a rotation axis (3a) of the polishing tool in order to be able to control a polishing removal function specifically on a surface of a workpiece (2) to be machined, - the polishing tool has integrated cooling channels through which the polishing agent suspension is supplied, and - the effect of at least one polishing grain on the workpiece surface can be influenced by changing the material properties.

2. Polishing tool (1) according to claim 1, characterized in that the changing material property of the polishing agent carrier (1b) is a hardness of a polishing carrier material, whereby a friction coefficient of the polishing agent carrier (1b) is adjusted.

3. Polishing tool (1) according to claim 2, characterized in that the hardness of the polishing carrier material changes rotationally symmetrically to the rotation axis (3a) of the polishing tool (1).

4. Polishing tool (1) according to one of claims 1 to 3, characterized in that the at least one material property changes locally only in individual areas of the polishing agent carrier (1 b).

5. Polishing tool (1) according to one of claims 1 to 3, characterized in that the at least one material property changes over the entire polishing agent carrier (1 b).

6. Polishing tool (1) according to one of claims 2 to 5, characterized in that the polishing agent carrier (1b) has a different hardness in different regions (9a, 9b, 9c) which are arranged along a predetermined direction or two mutually perpendicular, predetermined directions in a plane. - 20 - REVISED SHEET (RULE 91) ISA / EP 7. Polishing tool (1) according to one of claims 1 to 6, characterized in that cooling channels (7a, 7b, 7c) for transporting a polishing suspension are introduced perpendicular to the rotation axis (3a) into the polishing agent carrier (1b) in linear, concentric and / or free-form structures.

8. Polishing tool (1) according to one of claims 1 to 7, characterized in that cooling channels (8) for transporting a polishing suspension are introduced horizontally to the rotation axis (3a) into the polishing base body (1a) and the polishing agent carrier (1b).

9. Polishing tool (1) according to one of claims 1 to 8, characterized in that the polishing tool (1) is designed to change a polishing pressure.

10. Polishing tool (1) according to one of claims 1 to 9, characterized in that the polishing base body (1 a) and the polishing agent carrier (1 b) are connected to one another.

11. Polishing tool (1) according to one of claims 1 to 10, characterized in that the polishing tool (1) has an edge support (12) with an adapted hardness for the over-edge polishing.

12. Use of a polishing tool (1) according to one of claims 1 to 11, for the surface polishing and the sub-aperture polishing of technical surfaces.

13. A method for producing a graduated and adaptive polishing tool (1) for polishing with loose grain, consisting of a polishing base body (1a) and a polishing agent carrier (1b), comprising the following steps: - providing a negative mold of the polishing agent carrier (1 b), - feeding at least one polymer to at least one print head, - producing at least one layer on the negative mold with the print head, thereby forming the polishing agent carrier, wherein - at least two areas of the polishing agent carrier (1 b) with different material properties are produced.

14. The method according to claim 13, characterized in that the polymers are supplied via two separate print heads which operate sequentially or in parallel during the production of the at least one layer. - 21 - REVISED SHEET (RULE 91) ISA / EP 15. The method according to claim 13 or 14, characterized in that each polymer consists of at least two components, wherein the different components are each mixed with one another by a mixer and are metered into the print heads.

16. Method according to one of claims 13 to 15, characterized in that the at least one layer is cured by UV radiation.

17. Method according to one of claims 13 to 16, characterized in that at least one layer has a continuous hardness profile.

18. Method according to one of claims 13 to 17, characterized in that an additional polymer is introduced into each layer as a support material, which is removed by dissolving after the respective layer has been produced.

19. Method according to one of claims 13 to 18, characterized in that after the production of the at least one layer, the shape of the polishing agent carrier (1 b) is dressed in order to minimize a shape deviation.

20. Method according to one of claims 13 to 19, characterized in that after the production of the at least one layer, the shape of the polishing agent carrier (1 b) is dressed, wherein the shape of the polishing agent carrier (1 b) is adapted to a surface to be polished. - 22 - REVISED SHEET (RULE 91) ISA / EP

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