System and a method for the partial decoating of a coated surface of a glass body and a partial decoated glass body

Abstract

The invention relates to a system for the region-by-region decoating of a coated surface of a glass body, comprising a laser source (4) for generating a continuous laser beam, a focusing device (8) for focusing the laser beam onto the surface of the coated glass body (6), a scanning mirror arrangement (10) for directed scanning of the laser beam on the surface of the coated glass body (6) at a scanning speed of the laser beam on the surface, and a control device (18) for controlling the laser source (4) and the scanning mirror arrangement (10), wherein the laser source (4), the scanning mirror arrangement (10), and the control device (18) are configured to scan the continuous laser beam on the surface at a scanning speed of at least 10 m / s. The invention also relates to a method and a glass body.

Description

The invention relates to a system and a method for regional decoating of a coated surface of a glass body and to a regional decoating of a glass body.The invention is not limited to application to glass bodies and can also be applied to coated surfaces of bodies of other materials. The invention is also directed to decoating coatings, wherein the coating is either decoating as a whole or, in the case of a layer structure, only a part of the layers is decoating.Glass bodies of the type in question here are glass bodies with a planar functional coating which improves or only permits the intended use of the glass body. The glass body may alternatively or additionally have a protective coating which protects the surface of the glass body. Overall, the construction of one or more layers is referred to below as a coating.Glass bodies with flat functional coatings are used, for example, to reflect infrared radiation. Such glass bodies are used in glazing of buildings or in automobile construction. In addition to the functional coatings, protective coatings are also applied partially to large glass bodies, also called raw glasses, from which final formats are separated and subsequently further processed, which protective coatings are intended to be at least partially removed during the further processing.A planar removal of functional coatings is necessary in order to achieve adequate adhesion or sufficiently high adhesion of adhesives or paints, for example, at the edge of the panes in the case of glazing for buildings, vehicles, kitchen appliances, smart devices and other applications.In the prior art, such edge decoating or decoating of an inner region of the coating takes place via mechanical layer removal by means of grinding, in particular by means of rotating grinding bodies with a circumferential grinding kinematics. Edge delamination is probably the most common in insulating glazings. In simple insulating glazings for a window, it is often necessary for the coating to be circumferentially removed around the final size of the pane over a width of about 10 mm. As a rule, this takes place already on the glass blanks, i.e. before the glass blank is divided into the final formats. In this case, the coating is typically removed over a width of 20 mm, which corresponds to the width of the grinding tool. The glass is then cut in the middle of the grinding tracks by scribing and breaking, so that the final formats have a 10 mm wide edge.To produce the insulating glass, the individual panes are furthermore tightly connected in a circumferential manner at the glass edge to a spacer (spacer) and a primary seal and then a secondary seal. The edge bond thus produced is generally concealed in the window by the window frame, so that the quality requirements are limited to adequate adhesion of the adhesive and not to optical features.However, the present invention is not limited to the decoating of edge regions of glass bodies. In addition to edge delamination, inner regions of a coated surface of a glass body can also be delaminated.Achievable feed speeds during mechanical decoating are up to 1400 mm / s with a width of 20 mm, which corresponds to an area removal rate of approximately 28000 mm 2 / s. However, such a theoretical surface removal rate is difficult to implement only with a linear course of the grinding track, since during the back and forth process the grinding tools have to be mechanically advanced, turned and accelerated at the ends of the grinding tracks. Ultimately, there is always a lower "practical" surface removal rate.The surface removal rate corresponds to a surface speed at which the tool is moved over the surface and at which decoating takes place. The surface removal rate does not indicate the degree to which the removal leading to decoating leads.In the case of the high theoretical surface removal rate, it must also be taken into account that the layer removal takes place technologically rather in the form of a polishing process than a grinding process, i.e. very soft circumferential grinding wheels, also called round decoating wheels, are used and the glass surface remains substantially (specular). A disadvantage here is that the coating is also not removed completely and uniformly. In this case, for example, the coating can again deposit as coating material on the surface, partly on account of the circumferential grinding kinematics of the polishing tools. The re-deposited coating material, which is partially oxide-deposited on the surface, can hardly be removed by a washing process even by thermal interactions during the re-application later.Likewise, oscillations or slight run-out conditions up to regenerative effects on the grinding tool side can cause locally variable roughnesses and residual deposits on the surface of the glass body. In particular after the production of the edge composite, these locally variable roughnesses and deposits become clearly visible in the form of color and mirroring effects, which, however, plays no role as long as the adhesive properties are sufficiently good and the edge is covered by the window frame.In contrast to windows, the edge bond is frequently visible in demanding applications in glass facades such as structural glazing. Structural glazing or also structural sealant glazing denotes a type of glass facade construction in the glass pane exclusively by means of adhesive bonds. Press bars can be omitted. Mechanical loads absorb the bond, and the internal load of the panes is usually dissipated by a mechanical device lying in a concealed manner.Moreover, there are demanding applications in which the de-coated edge is printed. Printed step edge designs are desirable, for example, when the visible outer pane of the insulating glass projects laterally beyond the inner panes, for example, to cover the frame.In vehicle panes, in the area of kitchen appliances or in interior glazings, the outer, printed edge is frequently glued all around on a carrier or frame. The glued or printed edge region of the glass is wider than in window glazings. For optical reasons alone and also because of higher safety requirements compared to window glazings, a very uniform and reproducible layer removal and a uniform roughness are required in these cases.In order to ensure this by means of a circumferential grinding kinematics, a plurality of grinding tracks are positioned next to one another in a slightly overlapping manner. In addition, tools with a harder bond are used, so that in addition to the coating, the glass surface is also removed to a certain depth. This creates a uniform roughness of the surface and significantly less coating material is re-deposited on the surface due to the circumferential grinding kinematics, even because a part of the glass on the surface is removed. Due to the increased roughness and the "clean" surface, good adhesion and a sufficiently uniform optical impression can be achieved.In conventional grinding of the type described above, however, the theoretical surface removal rate that can be achieved is on average only about 5000 mm 2 / s. This is caused by the significantly lower possible feed speed and the partial superposition of the grinding tracks and partial doubling of the surface. Higher surface removal rates are subject to limits due to the thermal and mechanical loading of the grinding tools and of the glass itself. As the surface removal rate increases, the tool wear also increases progressively and the already very high tool costs therefore increase dramatically.From the prior art, a planar layer removal by means of a pulsed laser is also known.The conventional approach for removing or decoating coatings from the glass body takes place via pulsed lasers having a wavelength in the near infrared range (NIR range having wavelengths of approximately 1 μm) or having shorter wavelengths. Laser pulses in the nanosecond, picosecond or also femtosecond range are used. However, these systems with pulsed lasers are cost-intensive and limited in terms of output, so that the surface removal rates here are rather low.Nanosecond lasers may be used to make fine electrically insulating division lines in glass coatings. The pulse lengths are typically 100 ns or shorter. Laser sources of 100 watts power and a pulse repetition frequency of 100 kHz are typically used for this purpose. With a focus diameter of typically 50 μm and a pulse offset of 30 μm, scanning speeds of 3 m / s can be achieved with this.The object of the present invention is therefore to further improve a system and a method for decoating a part of a coated surface of a glass body and a partially decoating glass body.In particular, the object is to develop a cost-effective method and a corresponding system for planar stripping, which permits a qualitatively improved removal result with simultaneously higher productivity compared to conventional planar removal of glass coatings by grinding and compared to the use of pulsed lasers.The object indicated above is achieved according to the invention by a plant having the features of claim 1, by a use of the plant according to claim 8, by a method having the features of claim 9 and by a glass body having the features of claim 19. In addition, the object is achieved by a method according to claim 24.The invention is not limited to application to glass bodies and can also be applied to coated surfaces of bodies of other materials. The invention is also directed to decoating coatings, wherein the coating is either decoating as a whole or, in the case of a layer structure, only a part of the layers is decoating. However, the invention will be described with respect to decoating glass bodies.The system according to the invention for regional decoating of a part of a coated surface of a glass body has a structure with a laser source for generating a continuous laser beam, with a focusing device for focusing the laser beam onto the coated surface of the glass body, with a scanning mirror arrangement for directed scanning of the laser beam at a scanning speed on the surface of the coated glass body and with a control device for controlling the laser source and the scanning mirror arrangement, wherein the laser source, the scanning mirror arrangement and the control device are configured to scan the continuous laser beam at a scanning speed of at least 10 m / s on the surface.In this case, the scanning speed can preferably be at least 100 m / s, preferably at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s.The scanning speed to be used can thus be set in a wide range of values, wherein different further parameters such as the size and shape of the laser spot, the power of the laser beam and the material properties of the coating must be taken into account. Thus, the parameters for the application of a continuous laser beam for decoating can be set in a large value range or process window.In contrast to pulsed lasers, the laser pulses of which must be applied to the surface so closely as to ensure an at least continuous scanning track, according to the invention, the decoating of the surface of the glass body can be carried out with a continuous laser beam and the scanning speed can be increased as much as is possible for the energy applied by the continuous laser beam.A surprising aspect of the described system and method is that the required surface energy for good layer removal by means of a continuous laser beam with only approximately 0.1 J / mm 2 is lower than in the case of the application of a pulsed laser for a comparable layer removal.The advantage of continuous laser beams compared to pulsed lasers is also the significantly lower costs per kilowatts of laser power at the same laser wavelength and the significantly higher possible laser powers.The scanning speeds as well as the power of the laser beam generated by the continuous laser can be variably set over larger value ranges. This results in a large working range which can be used for decoating the glass body.The method for regional decoating of a coated surface of a glass body has the method steps in which a focused laser spot of a continuous laser beam is scanned over the surface of the coated glass body at a scanning speed of at least 10 m / s, and in which a coating of the surface of the glass body is decoating in the region scanned by the continuous laser beam.The method is preferably carried out in which the continuous laser beam is scanned on the surface at a scanning speed of at least 100 m / s, preferably at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s.The described parameters achieve a virtual pulse length which corresponds to the time span over which the surface to be decoating is impinged by the laser beam. For example, the virtual pulse length is 100 ns when a scanning speed of 1000 m / s and a focus diameter of 100 μm are present. The procedure is based on the aim of bringing the irradiation time or the virtual pulse length, which a single point on the glass surface experiences by scanning a continuous laser beam, to the level of the pulse length of nanosecond lasers.During the decoating of the surface, the continuous laser beam is applied to the surface in scanning tracks lying next to one another. In this case, the scanning tracks have a scanning distance less than the track width, such that adjacent scanning tracks partially overlap. The overlapping of the scanning tracks serves to equalize the energy input on the surface.Furthermore, the control device is configured to operate the laser source with a power of at least 1 kW, in particular at least 3 kW and preferably at least 5 kW. Thus, the laser powers can be increased up to the load-carrying capacity limits of the scanning mirror arrangement. Different lasers can be used or a laser is variably adjusted in its power over a partial range of the indicated power range.In particular, the laser beam can be scanned on the surface with a scanning width of at least 10 mm, preferably of at least 50 mm, preferably of at least 200 mm, in particular of 300 mm.On the surface of the coated glass body, the scanning speed and the scanning track spacing result in an area removal rate of at least 2000 mm 2 / s and an applied area energy in the range of 0.1 J / mm 2.The surface removal rate corresponds to a theoretical surface removal rate at which the surface is actually scanned and processed with a moving laser beam. The theoretical sampling rate does not include laser off times in which the surface cannot be processed.This is because due to technical conditions such as adjustment of the glass body relative to the optical system or vice versa, due to technical switch-off times of the continuous laser beam or other settings in the system, dead times result, so that a realistic or actual surface removal rate is only a fraction, for example of approximately 35 to 90%, of the theoretical surface removal rate. For example, a practical or actual surface removal rate of approximately 3500 mm 2 / s can be achieved with a theoretical surface removal rate of 5000 mm 2 / s.Depending on the adjustable parameters, the surface removal rate can also be increased, so that the surface removal rate is at least 2000 mm 2 / s, preferably at least 5000 mm 2 / s, in particular at least 15000 mm 2 / s and preferably at least 25000 mm 2 / s. The parameter of the surface removal rate is the greater the higher the scanning speed and the scanning track spacing are, wherein the required energy input into the surface is again dependent on the laser power.The laser source can furthermore be a single-mode laser, in particular a single-mode fiber laser or a multi-mode laser, in particular a multi-mode fiber laser. The use of fiber lasers is preferred because the use of complex beam deflections can be dispensed with.A standard single mode laser has the advantage that the switching on and off of the laser can be performed more accurately than is the case with multimode lasers. Another property is the better focusing property of the single mode laser.A multimode laser, on the other hand, has a higher laser power and a more uniform flat beam profile than a single mode laser. The beam profile which is flat in this way is also referred to as a top hat profile.Therefore, a possible increase in the theoretical surface removal rate with a simultaneous further cost reduction is the use of continuous multimode fibre lasers instead of continuous monomode fibre lasers. When the laser power is doubled compared to a single mode laser, the surface energy per mm is 2 and the virtual pulse length is identical if the beam diameter, the track spacing and the scanning speed increase by about 40 percent.The lasers mentioned preferably operate with a wavelength in the near infrared range (NIR range) with wavelengths of approximately 1 μm. However, other wavelength ranges are also possible. The wavelength range of approximately 1 μm is preferred in particular for cost reasons and because of the laser powers available in this wavelength range.For the operation of the apparatus, the focusing device is required in order to concentrate the laser power onto a small laser spot on the surface. The focusing device is configured for such focusing of the laser beam in the direction of the surface of the coated glass body, wherein the focused laser beam generates a laser spot having a dimension or beam diameter of preferably less than 120 μm. The beam diameter is usually defined by the drop in intensity to 1 / e 2 of the maximum value. The cross-sectional shape of the laser spot is generally round or oval; the dimension of the beam diameter here means in each case the largest diameter of an intensity distribution.The focusing device is configured such that the laser power leads to a desired input of surface energy. This does not necessarily mean that the laser spot corresponds to the focus. The distance between the focusing device and the surface of the glass body can thus be adjusted such that the laser spot is arranged on the surface in the focus position or just before the focus position or just after the focus position.Furthermore, it is preferred that a device for adaptive focus position adjustment is provided. With an adaptive focus position adjustment, distance changes between the scanning mirror arrangement and the surface of the glass body can be adapted in short time scales of milliseconds. For this purpose, piezoelectric elements and mirror surfaces connected thereto are preferably used in order to realize a rapid adaptation of the distance. Mirror surfaces of this type are also suitable for higher powers than galvanomirrors.Furthermore, it is preferred that the focusing device focuses the laser beam to a spot length transverse to the scanning direction of the laser beam that is at least 50% greater than the spot length in the scanning direction of the laser beam. The focus is thus stretched transversely to the scanning direction and the area acted upon by the laser spot is enlarged. The laser power is thus distributed over a larger area compared to a round focus. If the laser power can be sufficiently increased, the scanning speed can be maintained and the area removal rate can be further increased. For lower laser powers, the scanning speed can be reduced in order to achieve the same area removal rate as in the case of a round focus. Scanning thereby becomes slower, whereby the entire control by the control device is facilitated and, if necessary, an adaptive focus position adjustment can be dispensed with, in particular also in the case of short scanning paths or scanning widths. This can be advantageous in particular when removing layers from vehicle windows.Alternatively, the focusing device can focus the laser beam to a spot length in the scanning direction of the laser beam which is at least 50% greater than the spot length transversely to the scanning direction of the laser beam. The focus is thus stretched along the scanning direction and the area impinged by the laser spot is likewise enlarged. The laser power is thus also distributed over a larger area compared to a round focus. The virtual pulse length is thereby extended and the time duration of the input of the laser power is extended while the track width is maintained compared to a round laser spot.The distance between the focusing device and the surface of the glass body and also the intensity of the focusing in the scanning direction and transversely to the scanning direction can also be set such that the laser spot with its spot length is arranged transversely to the scanning direction on the surface in the focus position and the laser spot with its spot length is arranged in the scanning direction just before the focus position or just after the focus position. Likewise, the laser spot with its spot length in the scanning direction can be arranged on the surface in the focus position and the laser spot with its spot length transversely to the scanning direction can be arranged just before the focus position or just after the focus position.The scanning mirror arrangement can be designed as a galvanically or piezoelectrically driven scanning mirror or as a polygon scanner. In this case, the use of a polygon scanner is preferred because of the higher scanning speeds to be achieved and very constant scanning speeds due to the constant rotation of the polygon mirror. This is because the polygon scanner can generate a scanning speed on the surface of at least 10 m / s, preferably at least 100 m / s, preferably at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s. The power consumption of the above-mentioned galvanically driven scanning mirrors is limited, but can also be used here in principle.In addition, the polygon scanners can transmit powers of up to 5 kW and more with simultaneously high and constant scanning speed and large laser spots on the surface of the scanning mirrors, which enables a further increase in the theoretical surface removal rate. The polygon scanners are advantageous in this respect compared to galvanically operating scanning mirror arrangements. However, a corresponding future development in galvanic scanning mirror arrangements is not excluded.A polygon scanner serves to deflect the incident laser beam. For this purpose, a polygonal wheel is provided which rotates about a mechanical axis at a preferably constant angular speed. When the laser beam impinges on a flat specular surface or facet of the polygon wheel, the laser beam is deflected over an angular range and is thus scanned on a surface of the glass body. For the change between two successive polygonal surfaces, it is necessary to switch off the laser. This ensures that only one complete laser beam is deflected at a time and that no optical interference occurs due to reflections at the edge between two polygonal surfaces. The laser beam must therefore be switched off and on very quickly and precisely, and the effective time duration of the laser beam switched on is approximately 50%. In other words, the continuous laser is only turned on at 50% of the time, thereby reducing the practical area removal rate by half compared to the theoretical removal rate.If, on the other hand, scanning mirrors driven galvanically or with piezoelectric elements are used, in which the scanning direction can be reversed, no laser times or only very small laser times are necessary.The deflection results in a scan width with a defined starting and ending point. The scan course of successive scans is directed in the same direction. The scanning path and thus the scanning width of the laser beam is therefore limited by the maximum possible projection of the laser beam onto the surface by means of a respective polygonal surface of the polygon scanner and is at least 10 mm, preferably at least 50 mm, preferably at least 200 mm, in particular at least 300 mm. Thus, in a scanning process, regions of the coated surface having a width corresponding to the scanning width can be de-coated. The starting and ending points of each scan, i.e. the actual scan width, can also be actively controlled by selective switching on and off of the laser beam.Rotating polygon scanners are one-dimensional scanners that generate a scan line. In order to scan a two-dimensional surface, a second movement, in particular a linear movement, must be added. The alignment of the second linear movement is preferably effected-as in conventional applications also-perpendicular to the scanning line generated by the polygon scanner and the speed of the second linear movement is matched to the rotational speed of the polygon scanner. A raster scan of the surface is thus made possible, the required synchronization being provided by the control device. The second linear movement is realized by further scanning mirrors or by a positioning device.For this purpose, for example, galvanically or piezoelectrically driven tilting mirrors can be combined with the polygon scanner, so that smaller surface sections can be scanned without a relative movement of the glass body to the scanning mirror arrangement.A positioning device can alternatively or additionally be provided and serve for positioning the glass body relative to the scanning mirror arrangement. Preferably, the positioning device moves the glass body relative to a fixed scanning mirror arrangement and thus specifies the region of the surface decoating and the orientation of the surface relative to the scanning mirror arrangement.However, the relative movement can also be effected by a movement of a working head which has the laser source and the scanning mirror arrangement. The glass body is at rest and the working head is designed to be mechanically adjustable, for example by means of a robot. For example, such a working head can be used in the processing of bent glass panes, in particular vehicle panes.Finally, this can also be combined by moving both the glass body and the working head. For example, the glass body can be moved in one direction, while the working head is moved in a further spatial direction or in both further spatial directions. In addition, a rotation of the working head about one to three axes can also take place.By means of the relative movement between the working head with the scanning mirror arrangement and the glass body, a feed is realized, so that the scanning tracks are applied to the surface one after the other.This results in a feed speed which is the greater the faster the scanning speed and the greater the track spacing can be set.The orientation of the surface relative to the scanning mirror arrangement relates on the one hand to the angle of incidence of the laser beam on the surface. It is preferred that the angle of incidence of the laser beam extends substantially perpendicular to the surface. Inclined angles can alternatively be adjusted if decoating can thereby be improved.On the other hand, the scanning direction of the laser beam relative to the surface to be processed can be adjustable with respect to side edges of the glass body. This is because the preferred application of the apparatus and method is the decoating of edge regions adjacent to side edges. The orientation of the surface relative to the scanning mirror arrangement thereby relates to the angle of the scanning direction relative to the side edge of the region of the surface to be processed.If the scanning direction runs perpendicular to the side edge of the region of the surface to be processed, then a strip-shaped region of the edge-side surface can be de-coated with a width which corresponds to the length of the scanning path predefined by the scanning mirror arrangement.If, on the other hand, a strip-shaped region with a width of less than the length of the scanning path is to be de-coated, then the surface of the glass body with the side edge can be arranged at an angle to the scanning direction, so that the scanning direction is projected onto the surface and scanned at an angle different from 90° relative to the side edge. Thus, the entire scan path can be used for de-layering the area of the surface despite narrower width. In addition, the feed speed can be increased, since larger steps can be carried out in the feed direction in order to maintain the scan distance between the scan tracks.The above-mentioned method for regional decoating of a coated surface of a glass body is distinguished in that a continuous laser beam with a sufficient power at a high surface removal rate introduces a sufficient energy input into the coating of the glass surface, so that the coating is detached and removed.The laser energy of the continuous laser beam is introduced more uniformly into the coating via the scanning track than is the case with a pulsed scanning track. As a result, under certain circumstances even a lower laser power is required in order to carry out the decoating.The energy introduced by the laser beam mainly triggers thermal processes. Due to an abrupt thermal expansion of the coating, the coating is detached from the glass surface or an underlying further coating. After this, the material of the coating is partly evaporated and partly removed from the surface as small to smallest particles and partly evaporated. The optical image of a decoating operation of the type described above shows a development of steam or dust which can be sucked off, blown away or otherwise removed from the plant. For this purpose, a blowing or suction device can be provided, which cleans the respectively processed region.The above-described process can also be referred to as thermomechanical ablation process. This process is fundamentally different from decoating with pulsed lasers, in which a substantial change in material takes place. Depending on the layer structure made of different layers, different layers can interact with the laser beam to different extents and can accordingly be detached to different extents.In a further preferred embodiment of the method, the laser beam is focused to a spot length transversely to the scanning direction of the laser beam which is at least 50% greater than the spot length in the scanning direction of the laser beam. Wider scan tracks can thus be produced in order to achieve an equally good decoating with increased laser power at the same scan speed and thus to increase the surface removal rate. With the same laser power compared to a round laser spot, the scanning speed can be reduced in order to achieve the same surface removal rate. A reduced scanning speed thereby provides advantages for the control system for carrying out the method.Alternatively, when performing the method, the laser beam can be focused to a spot length in the scanning direction of the laser beam that is at least 50% greater than the spot length transverse to the scanning direction of the laser beam. The focus is thus stretched along the scanning direction and the area impinged by the laser spot is likewise enlarged. The laser power is thus also distributed over a larger area compared to a round focus. The virtual pulse length is thereby extended and the time duration of the input of the laser power is extended while the track width is maintained compared to a round laser spot.In order to achieve the most uniform possible decoating, scanning tracks of the laser scan lying next to one another are furthermore applied overlapping on the surface. It is preferred that scanning tracks lying next to one another are generated with a track spacing of at most 50% of the focal length of the laser spot transversely to the scanning direction. For example, with a focal length of the laser spot transversely to the scanning direction of 90 μm, the scanning tracks are applied with a distance between the centers of the scanning tracks of 40 μm. In this case, the track spacing between the center lines of two adjacent scan tracks is determined.During the regional decoating of the coated surface, slight soiling of the regions already decoating can occur. This is because the decoating or vaporized material of the coating partially condenses again and is deposited again on the surface to a small extent. Therefore, it is preferable that after a portion of the surface of the coated glass body is de-coated, deposits of the de-coated material are mechanically removed. For this purpose, various mechanical methods such as blowing off, aspiration, wiping, washing or other dry or wet methods can be used.This also ensures that the material does not deposit, but rather is removed. In addition, the process of removal can be supported by blowing off the de-coated material.The method described can be carried out from two sides of the glass body. On the one hand, the laser beam can be applied to the coated surface of the glass body. This results in a direct action of the laser beam on the coating and the glass material arranged under the coating in the beam direction is only slightly influenced or not at all. On the other hand, the laser beam can be applied to the surface lying opposite the coated surface, in most cases uncoated surface. In this case, the laser beam initially runs through the material of the glass body and then impinges on the coating from below for the decoating. The radiation pressure thus directed away from the surface of the glass body assists the detachment and decoating.Conventional coatings of glass bodies serve for reflecting infrared radiation and thus for a thermal improvement in the application of the glass body or glass pane. These coatings are also referred to as low-e coatings or sunscreen layers and can be made of reflective metals such as metals and their oxides. For example, gold, silver, copper, nickel-chromium, stainless steel, titanium, etc. or from their oxides are used. These materials have a high transmission in the visible spectral range and a high reflection in the infrared range.Such or also other coatings are applied, for example, using high vacuum magnetron methods, physical vapor deposition (PVD), chemical vapor deposition (CVD) and by the sol-gel method. In high vacuum magnetron methods, thin metal or metal oxide layers are deposited or sputtered in an electromagnetic process under high vacuum. In PVD processes, a thin layer is produced on the glass body by condensation from a vapor phase. In the CVD method, a thin layer is deposited from the vacuum and in the sol-gel method, it is a wet chemical method.The method described can also be applied to laminated glasses in which at least two glass sheets are joined together separately by a film. In this case, the parameters can be set such that the film within the laminated glass is not damaged.Furthermore, for better adhesion of the stated coating materials, an adhesion promoter layer can be arranged between the glass body and the actual coating. During decoating, the aim may be to remove the adhesion promoter layer as well or to at least partially obtain the adhesion promoter layer and not decoating. Barrier layers and / or ceramic-like protective layers can also be applied.A coating of a glass body, which can also be decoating in regions using the method described, can also consist of a applied or printed color layer. The ink layer can be de-coated in regions with the continuous laser beam in the described manner, wherein a desired pattern or a planar structure of coated regions, i.e. regions containing the ink layer, and de-coated regions is produced. The coating or the colored layer patterned or structured in this way is then fixed and / or cured, for example by means of a heat treatment in an oven. One application is, for example, the production of front panes of kitchen appliances.With the method described, it is possible that by scanning the region of the glass surface to be decoating once at least 95%, preferably at least 99% of the coating material is removed.In the case of multilayer coatings, for example with an adhesion promoter layer, it can also be achieved that the adhesion promoter layer remains, but a layer structure located above it is removed to an extent of at least 95%, preferably at least 99%, of the coating material.For carrying out the method, there is in each case at least one parameter range in which good decoating of the surface is achieved. In this case, there is a lower threshold for the surface energy, starting from which sufficient decoating is first achieved. However, the parameter range is also limited upward, since an excessively large introduced surface energy can damage the glass surface arranged under the coating or a further layer arranged below it. Processing of the glass surface, on the other hand, may be wanted in order to achieve a specific surface roughness, but also in this case the surface energy to be introduced is limited upward. If the surface energy is too high, thermally induced surface defects and / or fractures in the glass body may occur, for example, as a result of the decoating.The process window, i.e. the combination options of the various parameter ranges with possible settings, is very large for the methods described above. Thus, decoating can be set with a plurality of possible combinations of laser power, scanning speed, scanning width, angle of the scanning direction relative to the side edge of the glass body and / or spot lengths transversely to the scanning direction and in the scanning direction.The object indicated above is also achieved by a glass body having a structure with a base body made of a glass material, wherein the base body has a surface with a first surface region and with a second surface region, wherein the first surface region has a coating, and wherein the coating is at least partially de-coated in the second surface region by processing, and wherein the de-coated region has a multiplicity of continuous scanning tracks lying next to one another.The scanning tracks of a glass body according to the invention are on the one hand adjacent to one another and overlap one another. In addition, the scanning tracks are continuous in the sense that each scanning track is machined with a continuously identical laser power by the continuous laser beam. Thus, only a few and slight differences in the decoating occur along the scan tracks, so that the scan tracks are characterized by a uniform, i.e. continuous, geometric profile.Thus, the continuous scanning tracks can be distinguished from scanning tracks introduced with a pulsed laser in the second region of a glass surface. The scanning tracks introduced with a pulsed laser have points which can be delimited from one another and preferably predominantly overlap one another along the scanning track.Another property of a continuous laser de-coated glass surface is that the boundary between the first region and the second region has an irregularity of an order of magnitude in the size of the distance between the scan tracks. This structure is due to the property of a continuous laser that the switching on and off of the laser can only be effected with a limited time accuracy. This property is also called jitter. Thus, the start or end points of a laser track on the surface cannot be introduced exactly along a boundary line because of the high scanning speeds. This creates an irregular characteristic boundary.The boundary line becomes flatter along the boundary, i.e. more regular, the greater the angle at which the laser steel is scanned over the surface.In the second surface region, at least 95%, preferably at least 99% of the coating material is removed in the region of the uncoated area.Furthermore, a small proportion of particulate material of the at least partially removed coating can be arranged in the second surface region. This is because the de-coated and possibly vaporized material can condense again and deposit again to a small extent on the surface. This characteristic deposit of the material can be determined for determining the degree of decoating that has been carried out.The object indicated above is also achieved by a method for regional decoating of a coated surface of a glass body, in which a focused laser beam is scanned over the surface of the coated glass body and in which a coating of the surface of the glass body is decoating in the region scanned by the laser beam and in which the scanning direction of the laser beam relative to the surface to be processed is set to an angle different from 90° with respect to side edges of the glass body.This method can be carried out both with continuous lasers and with pulsed lasers and is thus independent of the solutions of the object described above.Both for continuous lasers and for pulsed lasers, the previously described advantages arise in the decoating of regions of a coated surface when the laser beam is scanned at an angle different from 90° with respect to the side edge. In particular, if the scanning width is longer than the width of the region to be de-coated, a larger proportion or the entire scanning width of the laser track on the surface can be used for de-coating by obliquely guiding the laser beam on the surface at an angle different from 90°.Here too, it applies that the boundary line along the boundary between the de-coated region and the further coated region is formed to be flatter, i.e. more regular, the greater the angle is, i.e. the diagonal at which the laser steel is scanned over the surface.The invention is explained in more detail below with reference to exemplary embodiments. The drawing shows FIG. 1 shows a plant for regional decoating of a coated surface of a glass body, FIG. 2 shows a schematic illustration of the scanning paths during the execution of a method for regional decoating of a coated surface of a glass body in a first variant, FIG. 3 shows a schematic illustration of the scanning paths during the execution of a method for regional decoating of a coated surface of a glass body in a second variant, FIGS. 4a-b are photographic representations of de-coated regions of surfaces of glass bodies with de-coating by means of a pulsed laser (a) and with a continuous laser (b), FIG. 5 is a schematic illustration of the boundary line between de-coated and coated regions of the surface of a glass body; and FIGS. 6 a- c show exemplary embodiments of various geometries of focused laser spots on the surface of a glass body.The invention is described below with reference to exemplary embodiments for the decoating of glass bodies. However, the invention is not limited in principle to application to glass bodies and can also be applied to coated surfaces of bodies made of other materials. The invention is also directed to decoating coatings, wherein the coating is either decoating as a whole or, in the case of a layer structure, only a part of the layers is decoating. However, the invention will be described with respect to decoating glass bodies.FIG. 1 shows a system 2 for regional decoating of a coated surface of a glass body 4 with a coating 5.The system 2 first comprises a laser source 6 for generating a continuous laser beam, the laser source is thus a cw laser source, wherein cw stands for continuous wave.The system 2 also has a focusing device 8 for focusing the laser beam onto the surface of the glass body 4, wherein the focused laser beam generates a laser spot on the surface of the glass body. The focusing device 8 has an arrangement of lenses which is known per se and which bring about the focusing of the laser beam. A lens 8a is shown symbolically.A scanning mirror arrangement 10 for directed scanning of the laser beam on the surface of the glass body 4 is provided in order to scan the laser beam on the surface of the glass body 4 at a predetermined scanning speed of the laser beam and a predetermined scanning path with a scanning width corresponding to the arrow 12.In the present case, the scanning mirror arrangement 10 is designed as a polygon scanner and has a polygon wheel 10 awhich rotates about a mechanical axis at a preferably constant angular speed (see arrow 13). When the laser beam impinges on a flat specular surface or facet 10b of the polygon wheel 10a, the laser beam is deflected over an angular range and is thus scanned on the surface of the coated glass body 4. The scanning direction therefore depends on the direction of rotation of the polygon scanner 10.Furthermore, a positioning device 14 is provided for positioning the glass body 4 by linear and rotating movements relative to the scanning mirror arrangement 10. The positioning device 14 moves the glass body 6 in two movement directions perpendicular to the incident laser beam, which is symbolized by crossed arrows 16 ain FIG. 1. The rotating movement is symbolized by the arrow 16 b, it being possible to allow a rotation about up to three axes. The positioning device 14 can also be configured to move the glass body 6 with a movement direction parallel to the alignment of the laser beam. This is particularly advantageous when the system 2 is used for curved surfaces of glass bodies 6, for example curved vehicle windows, or for readjustment of distance fluctuations.The laser 6, the focusing device 8 and the positioning device 10 are combined in a working head 11 which can be moved as a unit. In this case, the working head 11 can be moved in two movement directions perpendicular to the incident laser beam, which is symbolized by crossed arrows 17 ain FIG. 1. A rotating movement is likewise possible, which is symbolized by a rotating arrow 17 b. This rotating movement can also take place about up to three axes.Furthermore, at least one movable mirror can be arranged between the laser 6 and the polygon scanner 10 or between the polygon scanner 10 and the glass body 4 in order to enable an additional movement component for scanning the laser beam on the surface. Such a movable mirror is not shown in FIG. 1 for reasons of better clarity.A control device 18 schematically depicted in FIG. 1 is provided for controlling the laser source 6, the scanning mirror arrangement 10 and the positioning device 16. The connecting lines between the components are shown with dashed double arrows.In this case, the laser source 6, the scanning mirror arrangement 10 and the control device 18 are configured to scan the continuous laser beam on the surface at a scanning speed of at least 10 m / s. The laser beam is preferably scanned at a scanning speed of at least 100 m / s, preferably of at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s. The advantages of an increased scanning speed is an increased productivity.The laser source 6 can be operated with a power of at least 1 kW, in particular at least 3 kW and preferably at least 5 kW.This results in a working window for decoating the surface of the glass body 4 with a range of possible scanning speeds and a range of usable laser powers, so that decoating can be adjusted depending on the properties of the coating 5, such as material, thickness and hardness. In addition, adjustable parameters are the scan width and the track pitch that affect de-layering.By scanning the laser beam, a theoretical surface removal rate of at least 2000 mm 2 / s, which is to be calculated from the scanning speed and the track spacing, can be generated on the surface of the glass body 4 with the coating 5. The surface removal rate can also be at least 5000 mm 2 / s, in particular at least 15000 mm 2 / s and preferably at least 25000 mm 2 / s.The surface energy applied to the surface of the coating 5 is in the range of 0.1 J / mm 2. for example.The laser source 6 is configured as a single mode laser or as a multimode laser and generates a laser beam having a wavelength in the range of 1 μm, i.e. in the near infrared range (NIR).The focusing device 8 is configured for focusing the laser beam onto the surface 5 of the glass body 4 such that the focused laser beam generates a laser spot having a dimension of less than 120 μm in the scanning direction.By constructing the polygonal mirror 10 and rotating it at a constant angular velocity, the maximum possible scanning width of the laser beam is fixed by the projection of the laser beam by means of a respective polygonal surface 10 bof the polygonal scanner 10 onto the surface and is predetermined by the distance of the polygonal scanner 10 from the coated surface. The scan width is, for example, at least 10 mm, preferably at least 50 mm, preferably at least 200 mm, in particular at least 300 mm.In FIG. 1, the scan width is indicated by the length of the arrow 12 on the coating 5 and is likewise shown by arrow lengths in the FIGS. 2 and 3 considered below.FIG. 2 schematically shows a glass body 4 with a plan view of the surface with the coating 5. The first surface region 5 aof the coating should remain after the decoating, while the encircling second surface region 5 bis to be decoating as an edge region in which a plurality of arrows is drawn. The second surface region 5 bis bounded outwardly by the side edges of the glass body.The method according to the invention for regional decoating of a coated surface 5 of a glass body 4 has the steps in which a focused continuous laser beam is scanned over the surface 5 of the coated glass body 4 at a scanning speed of at least 10 m / s and in which a coating of the surface of the glass body is decoating in the region scanned by the continuous laser beam.The coated surface of the glass body can thus be scanned with a theoretical surface removal rate of at least 2000 mm 2 / s resulting from the scanning speed and from the track width and with an applied surface energy of approximately 0.1 J / mm 2.The scanning movement of the laser beam on the surface is illustrated by the arrows 12. The length of the arrows corresponds to the scanning path or the scanning width which results from the geometry of the polygonal mirror 10 and the distance between the polygonal mirror 10 and the glass body 4. The length of the scanning path is marked at the top right in FIG. 2 with A. In general, scanning can be carried out from the outside to the inside or from the inside to the outside, but it is preferred when decoating a glass body 4 if scanning is carried out from the outside to the inside or from the inside to the outside on all side edges.In FIG. 2 and also in FIG. 3 discussed below, the track spacings are not drawn true to scale, but rather much too large. This is for better illustration and comparative purposes.The scanning path is set such that the scanning track begins or ends a few millimeters outside the glass edge on the basis of positioning and dimensional tolerances of glass bodies, positioning tolerances of the scanning mirror arrangement and tolerances of the scanning path in a real application.First, the decoating of the upper edge portion will be described. On the left side edge of the upper second surface region 5 b, a first scan 12 ais carried out starting from above up to the end of the scan path, represented by the arrow head, and the material of the coating is de-coated. The laser beam on the surface has a defined scanning speed and a defined width transverse to the scanning direction and a defined length in the scanning direction of the laser spot. The scanning direction runs here substantially perpendicular to the side edge.Thereafter, the relative position of the glass body 4 is changed by one track pitch by adjusting in the feed direction shown by the arrow B. The track spacing is marked on the upper side with the letter C and is shown too large in FIG. 2 and not to scale. The adjustment can be carried out in an interval-like manner, so that all scanning tracks lying next to one another are applied when the glass body is stationary relative to the polygon scanner. Alternatively, a continuous movement of the glass body relative to the polygon scanner can be carried out, so that equidistant scanning tracks are likewise introduced. As a result, the scanning tracks run slightly at an angle to the side edge of the glass body 4.The de-coating is then carried out by a next scan along the arrow 12b and the adjustment and scanning is continued until the last scan along the arrow 12c is carried out on the right edge. Thus, the material of the coating has been removed over the entire upper second surface region 5 bby equidistant scanning tracks. The width D of the second surface region 5 bsubstantially corresponds to the length A of the scanning paths of the laser beam.Scanning tracks 12 a, 12 b, etc. lying next to one another are generated with a track spacing of at most 50% of the width of the laser spot transversely to the scanning direction. The track distance is measured, for example, between the center of the track 12 aand the center of the track 12 b.Subsequently, the other edges of the coated surface 5 of the glass body 4 can be de-coated.When one of the second surface regions 5 bis decoating, the scanning tracks can be applied either starting from the side edge in the direction of the inner coated first surface region 5 aor starting from the inner coated first surface region 5 ato the outside as far as the side edge. Since the scanning paths are exactly predetermined and have the same length, substantially smooth edges of the de-coated regions are produced, in particular at the inner edges.The example according to FIG. 2 shows a de-lamination of edge regions with a width which corresponds to the length of the scanning path of each individual scan of the laser beam over the surface, that is to say for example 20 mm or 30 mm. However, if edge regions with a smaller width D are to be de-coated with identical scanning paths A, a part of the scanning path remains unused in a scanning direction running substantially perpendicular to the side edge.Fig. 3 shows a solution to this problem by adjusting the scanning direction of the laser beam relative to the surface 5 to be processed with respect to side edges of the glass body 4. In FIG. 3, the scanning direction runs obliquely at a defined angle of approximately 80° to the side edge. By means of this angle, the scanning path, which is represented by the length of the arrows 12 in the same way as in FIG. 2, can be applied completely to the coating 5.The length of the scanning paths is again marked A, the displacement direction for de-layering the upper edge region is marked B and the track spacing C. The width D of the edge region D to be de-coated is significantly smaller than the scanning path A.Due to the angle of the scanning direction of 80° with respect to the side edge, not only is the entire scanning path utilized, but the advancement of the glass body 4 relative to the scanning mirror arrangement and thus the de-lamination of the second surface region 5 bcan take place more quickly, since fewer laser scans are required, which also results directly from the different number of arrows 12 in FIGS. 2 and 3. Thus, the feed speed becomes faster by the quotient of the narrowing of the edge decoating. For example, the feed rate may be increased from 1.75 m / min.times.300 mm / 52 mm to 10 m / min. Likewise, the width of the transition region between the de-coated region and the coated region can be reduced with the same quotient.The method shown in FIG. 3 for regional decoating of a coated surface of a glass body can be carried out on the one hand with a continuously operating laser, as described with reference to FIG. 2. The method can also be carried out with a pulsed laser and is in this respect independent of the application with a continuous laser.FIGS. 4 aand 4 b show photographic representations of de-coated regions of surfaces of glass bodies with de-coating by means of a pulsed laser (a) and with a continuous laser (b).In FIG. 4a, scanning tracks 12' can be seen on the surface of the glass body 4, which tracks are visibly composed of individual points which have been introduced successively along the scanning direction (from left to right).In contrast, FIG. 4 bshows a de-coated region of a glass body 4 which has been de-coated with a continuous laser. The scanning tracks 12 are continuous and form a continuous course. The boundary lines between the adjacent scan tracks 12 are seen as light lines which have been emphasized by contrast enhancement of the image.FIG. 5 shows another characteristic of a glass surface de-coated with a continuous laser. A section of a surface of a glass body 4 with a first surface region 5 a(top) and a second surface region 5 b(bottom) is shown. The second surface region 5 bhas been de-coated with a continuous laser, wherein the scanning tracks 12 have been applied running from bottom to top. For better illustration, the scan tracks are shown alternately with a dashed line and with a dashed line. The boundary line 14, on the other hand, is shown fully solid.The boundary line 14 between the first region 5 aand the second region 5 bhas an irregularity of an order of magnitude in the size of the distance between the scan tracks. This structure is due to the property of a continuous laser 6 (see FIG. 1 ) that the switching on and off of the laser can only be effected with a limited temporal accuracy. This property is also called jitter. Thus, the beginning or end points of a laser track 12 cannot be introduced exactly along a straight boundary line 14 on the surface because of the high scanning speeds. This creates an irregular, but characteristic boundary or boundary line 14.The boundary line 14 is schematically shown as a solid line in FIG. 5. In a real application, the boundary line 14 will not be so clearly recognizable, since a transition region with decreasing degree of decoating arises when the continuous laser beam and the applied scanning speed are switched on or off.At a scanning speed of 1000 m / s, for example, the laser 6 (see FIG. 1 ) would have to be switched off with a temporal accuracy of + / - 0.5 μs in order to maintain an accuracy in the range of + / - 50 μm in the order of magnitude of the track spacing during a scanning perpendicular to the side edge of the glass body 4. When an angle of the scanning direction is set from 80° to the side edge, the accuracy is improved to + / - 9 μm.For these reasons, the two surface regions 5 aand 5 bdisplay a characteristic profile at their boundary lines 14, as is illustrated in FIG. 5.The boundary line 14 shown is typical for decoating with a continuous laser 6.Examples of prior art decoating processes and in accordance with the present invention are discussed below.FIGS. 6a to 6c show different geometric shapes of the focused laser spot 20 on the surface, the dashed lines indicating the scan tracks of different widths. FIG. 6 ashows a substantially round laser spot 20 in which the laser beam has a spot length transverse to the scanning direction of the laser beam of the same size as the spot length in the scanning direction of the laser beam.FIG. 6 bshows an embodiment of the laser spot 20 in which the spot length transverse to the scanning direction of the laser beam is 50% greater than the spot length in the scanning direction of the laser beam.FIG. 6 cshows a configuration of the laser spot 20 in which the spot length transverse to the scanning direction of the laser beam is 200% greater than the spot length in the scanning direction of the laser beam.The focusing device 8 has an arrangement of at least one cylindrical or otherwise non-rotationally symmetrical lens 8 ato generate the different spot lengths.Due to the different laser spots with different spot lengths transversely to the scanning direction, the scanning speed can be reduced with the same surface removal rate. The scanning speeds are shown in FIGS. 6a to 6c with arrows of different lengths. Here, it is schematically shown that the wider the focus is transversely to the scanning direction, the slower the scanning speed can be with approximately the same surface energy in order to achieve the same surface removal rate. The laser power is set in such a way that in each case sufficient surface energy is introduced into the coating. This is, for example, approximately 0.1 J / mm 2.First, the possible parameter ranges for carrying out the method according to the invention with a continuous laser beam, which are used in the examples, are specified.The laser beam may be reduced to a focus diameter of less than 120 μm.The polygon scanner 10 can generate a scanning speed on the surface of at least 100 m / s, preferably at least 350 m / s, in particular of at least 500 m / s and in particular of at least 1000 m / s.The surface removal rate is at least 2000 mm 2 / s, preferably at least 5000 mm 2 / s, in particular at least 15000 mm 2 / s and preferably at least 25000 mm 2 / s.The laser source 6 can be operated with a power of at least 1 kW, in particular at least 3 kW and preferably at least 5 kW.The surface energy applied is in the range of 0.1 J / mm 2.The laser beam can be scanned on the surface with a scanning width of at least 10 mm, preferably at least 50 mm, preferably at least 200 mm, preferably 300 mm.The values for the off time include, among other things, the necessary times for adjusting the laser beam between adjacent tracks and for accelerating and decelerating and rotating the mirror scanner at the side edges of the glass body. This off time is multiplied by the momentary turn-off of the laser corresponding to a duty cycle (in percent) to calculate the practical area removal rate from the theoretical area removal rate. In addition, the reduction of the laser power at the ends of the scan tracks can also be taken into account.Reference is made to a decoating with conventional surface grinding. With conventional grinding, a theoretical surface removal rate of approximately 8000 mm 2 / s and a practical surface removal rate of approximately 4000 mm 2 / s can be achieved.Examples 1 and 2 relate to applications of pulsed lasers for comparison with Examples 3 to 5 with continuous lasers.Example 1:pulsed single-mode fiber laser with galvanoscanner- Average laser power 50 W-- Pulse length 100 ns- Pulse frequency 100 kHz with a pulse interval of 10 μs-- Spot length in the scanning direction on surface 50 μm- Spot length transverse to the scanning direction on surface 50 μm-- Track pitch 25 μm- Scanning speed 2.5 m / s- Duty cycle of the laser 100%-- Timeout 10%- Surface processing- Scan width 100 mm-- Feed speed 0.6 mm / s- Theoretical surface removal rate 63 mm 2 / s- Practical Area Removal Rate 56 mm 2 / s- Surface energy 0.8 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical Surface Removal Rate: 0.8%- Practical Area Removal Rate: 1.4%Example 1 shows that a pulsed laser with low laser power has a very low surface removal rate compared to mechanical decoating.Example 2:pulsed single-mode fiber laser with polygon scanner- Average laser power 1 kW-- Pulse length 60 ns-- Pulse frequency 4 MHz with a pulse interval of 250 ns-- Spot length in the scanning direction on surface 60 μm-- Spot length transverse to the scanning direction on surface 60 μm- Track pitch 30 μm- Scanning speed 120 m / s-- Duty cycle of the laser 50%- Timeout 30%- Surface processing-- Scan width 300 mm-- Feed speed 6 mm / s- theoretical surface removal rate 3600 mm 2 / s- Practical Area Removal Rate 1260 mm 2 / s- Surface energy 0.28 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical surface removal rate: 23%- Practical Area Removal Rate: 32%With increased laser power of the pulsed laser according to Example 2, higher ablation rates are indeed achieved, but these are still far below the mechanically achievable values.Examples 1 and 2 show applications of pulsed lasers with which a homogeneous removal of a coating can be achieved. However, the surface removal rates are low and are below 2000 mm 2 / s.Example 3: Example 3:continuous single-mode fiber laser with polygon scanner- Laser power 2 kW-- Spot length in the scanning direction on surface 90 μm-- Spot length transverse to the scanning direction on surface 90 μm-- Track pitch 50 μm-- Scanning speed 350 m / s- virtual pulse length 257 ns-- Duty cycle of the laser 50%- Timeout 30%- Surface processing-- Scan width 300 mm-- Feed speed 29 mm / s- Theoretical surface removal rate 17325 mm 2 / s- Practical Area Removal Rate 6064 mm 2 / s- Surface energy 0.115 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical surface removal rate: 108%- Practical Area Removal Rate: 152%Even with a moderate laser power of a standard continuous laser, considerably higher surface removal rates are achieved than with a more powerful pulsed laser, in particular due to the lower required surface energy. The theoretical surface removal rate is in the range of mechanical decoating methods, the practical surface removal rate being significantly greater than in the case of mechanical methods.Example 4: Example 4:continuous single-mode fiber laser with polygon scanner- Laser power 3 kW-- Spot length in the scanning direction on surface 90 μm-- Spot length transverse to the scanning direction on surface 90 μm-- Track pitch 45 μm- Scanning speed 500 m / s- virtual pulse length 180 ns- Scanner Duty Cycle 50%- Timeout 30%- Surface processing-- Scan width 300 mm-- Feed speed 34 mm / s- Theoretical surface removal rate 20250 mm 2 / s- Practical Area Removal Rate 7090 mm 2 / s- Surface energy 0.148 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical surface removal rate: 127%- Practical Area Removal Rate: 177%Example 5: Example 5:continuous multimode fiber laser with polygon scanner- Laser power 5 kW-- Spot length in the scanning direction on surface 105 μm-- Spot length transversely to the scanning direction on surface 105 μm-- Track pitch 55 μm-- Scanning speed 650 m / s- virtual pulse length 162 ns- Scanner Duty Cycle 50%- Timeout 30%- Surface processing-- Scan width 300 mm- Feed speed 57 mm / s- Theoretical Surface Removal Rate 34125 mm 2 / s- Practical Area Removal Rate 11945 mm 2 / s- Surface energy 0.147 J / mm 2Ratio to the surface removal rate in conventional grinding:- theoretical surface removal rate: 213%- Practical Area Removal Rate: 299%Examples 3 to 5 show applications according to the invention with continuous laser beams, with which very homogeneous removal of the coating can be achieved, which removal is improved compared to the applications of pulsed lasers. With the improved decoating of the surface, high surface removal rates of above 2000 mm 2 / s and in some cases significantly above 5000 mm 2 / s can also be achieved with simultaneously comparatively lower surface energies.The further examples 6 to 8 correspond to examples 3 to 5, wherein the laser spot has been widened transversely to the scanning direction, whereby the surface removal rates can be increased again. Further, the scan width is 50 mm before instead of 300 mm before. The feed speeds can, on the other hand, be selected to be significantly higher.Example 6:continuous single-mode fiber laser with polygon scanner- Laser power 2 kW-- Spot length in the scanning direction on surface 90 μm-- Spot length transverse to the scanning direction on surface 315 μm-- Track pitch 170 μm- Scanning speed 100 m / s- virtual pulse length 900 ns-- Duty cycle of the laser 50%- Timeout 30%- Surface processing- Scan width 50 mm-- Feed speed 173 mm / s- Theoretical surface removal rate 17325 mm 2 / s- Practical Area Removal Rate 6064 mm 2 / s- Surface energy 0.115 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical surface removal rate: 108%- Practical Area Removal Rate: 152%Example 7:continuous single-mode fiber laser with polygon scanner- Laser power 3 kW-- Spot length in the scanning direction on surface 90 μm-- Spot length transversely to the scanning direction on surface 450 μm-- Track pitch 245 μm- Scanning speed 100 m / s- virtual pulse length 900 ns- Scanner Duty Cycle 50%- Timeout 30%- Surface processing- Scan width 50 mm-- Feed speed 341 mm / s- Theoretical surface removal rate 20250 mm 2 / s- Practical Area Removal Rate 7090 mm 2 / s- Surface energy 0.148 J / mm 2Ratio to the surface removal rate in conventional grinding:- Theoretical surface removal rate: 127%- Practical Area Removal Rate: 177%Example 8:continuous multimode fiber laser with polygon scanner- Laser power 5 kW-- Spot length in the scanning direction on surface 105 μm- Spot length transverse to the scanning direction on surface 683 μm-- Track pitch 341 μm- Scanning speed 100 m / s- virtual pulse length 1050 ns- Scanner Duty Cycle 50%- Timeout 30%- Surface processing- Scan width 50 mm-- Feed speed 341 mm / s- Theoretical Surface Removal Rate 34125 mm 2 / s- Practical Area Removal Rate 11945 mm 2 / s- Surface energy 0.147 J / mm 2Ratio to the surface removal rate in conventional grinding:- theoretical surface removal rate: 213%- Practical Area Removal Rate: 299%

Claims

Installation for regional decoating of a coated surface of a glass body, - with a laser source (4) for generating a continuous laser beam, - with a focusing device (8) for focusing the laser beam onto the surface of the coated glass body (6), - with a scanning mirror arrangement (10) for directed scanning of the laser beam at a scanning speed on the surface of the coated glass body (6) and - with a control device (18) for controlling the laser source (4) and the scanning mirror arrangement (10), - wherein the laser source (4), the scanning mirror arrangement (10) and the control device (18) are configured to scan the continuous laser beam at a scanning speed of at least 10 m / s on the surface.The system according to claim 1, characterized in that the scanning speed is at least 100 m / s, preferably at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s.The installation according to claim 1 or 2, characterized in that the control device (18) is configured to operate the laser source (4) with a power of at least 1 kW, in particular at least 3 kW and preferably at least 5 kW.System according to one of Claims 1 to 3, characterized in that the scanning mirror arrangement has a polygon scanner (10).The system according to claim 4, characterized in that the scanning width through the projection of the laser beam by means of a respective polygonal surface of the polygon scanner onto the surface is at least 10 mm, preferably at least 50 mm, preferably at least 200 mm, in particular at least 300 mm.The installation according to any one of claims 1 to 5, characterized in that the scanning direction of the laser beam relative to the surface to be processed is adjustable to an angle different from 90° with respect to side edges of the glass body.System according to one of Claims 1 to 6, characterized in that the focusing device (8) focuses the laser beam to a spot length transversely with respect to the scanning direction of the laser beam which is at least 50% greater than the spot length in the scanning direction of the laser beam.Use of a plant according to one of Claims 1 to 7 for the regional decoating of a coated surface of a glass body.Method for regional decoating of a coated surface of a glass body, - in which a focused laser spot of a continuous laser beam is scanned over the surface of the coated glass body at a scanning speed of at least 10 m / s, and - in which a coating of the surface of the glass body is decoating in the region scanned by the continuous laser beam.Method according to claim 9, wherein the continuous laser beam is scanned on the surface at a scanning speed of at least 100 m / s, preferably at least 300 m / s, in particular at least 500 m / s or preferably at least 1000 m / s.Method according to claim 9 or 10, in which a laser beam with a power of at least 1 kW, in particular at least 3 kW and preferably at least 5 kW is used.Method according to one of Claims 9 to 11, in which the laser beam is scanned on the surface with a scanning width of at least 10 mm, preferably of at least 50 mm, preferably of at least 200 mm, in particular of 300 mm.Method according to one of claims 9 to 12, wherein a theoretical surface removal rate of at least 2000 mm 2 / s, preferably at least 5000 mm 2 / s, in particular at least 15000 mm 2 / s and preferably at least 25000 mm 2 / s is achieved.The method according to any one of claims 9 to 13, wherein the scanning direction of the laser beam relative to the surface to be processed is set to an angle different from 90° with respect to side edges of the glass body.Method according to one of Claims 9 to 14, in which the laser beam is focused to a spot length transversely with respect to the scanning direction of the laser beam which is at least 50% greater than the spot length in the scanning direction of the laser beam.Method according to one of Claims 9 to 15, in which adjacent scanning tracks are produced with a track spacing of less than 50% of the diameter of the laser beam.Method according to one of Claims 9 to 16, in which deposits of the de-coated material are removed mechanically after a region of the surface of the coated glass body has been de-coated.Glass body - having a base body (4) made of a glass material, - wherein the base body (4) has a surface with a first surface region (5a) and with a second surface region (5b), - wherein the first surface region (5a) has a coating, and - wherein the coating is de-coated at least in regions in the second surface region (5b) by processing, and - wherein the de-coated region has a multiplicity of continuous scanning tracks lying next to one another.The glass body according to claim 18, characterized in that the boundary between the first area and the second area has an irregularity of an order of magnitude in the size of the distance between the scanning tracks.Glass body according to claim 18 or 19, characterised in that at least 95%, preferably at least 98%, of the coating is removed in the second surface region (5b).Glass body according to one of Claims 18 to 20, characterized in that a small proportion of particulate material of the at least partially removed coating is arranged in the second surface region (5b).Method for regional decoating of a coated surface of a glass body, - in which a focused laser beam is scanned over the surface of the coated glass body, and - in which a coating of the surface of the glass body is decoating in the region scanned by the laser beam, and in which the scanning direction of the laser beam relative to the surface to be processed is set to an angle different from 90° with respect to side edges of the glass body.

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