GLASS OR GLASS-CERAMIC PLATE AND METHOD FOR PRODUCING SUCH PLATES

Description

[0001] The invention relates to a glass or glass-ceramic plate according to the preamble of claim 1. The invention also relates to a method for producing such glass or glass-ceramic plates according to claim 6 and claim 10.

[0002] Glass or glass-ceramic panels are manufactured with or without facets, depending on their intended use. Such glass or glass-ceramic panels are typically rectangular in shape and, to ensure dimensional accuracy and safe handling, are first subjected to a peripheral grinding process known as pre-grinding. This grinding creates a profile with a defined edge geometry and eliminates sharp transitions and defects that may arise, for example, from the upstream "glass breaking" process. During this pre-grinding, the corners of the panel are usually rounded. The corner radii of the rounded edges merge into the straight sides of the panel, creating a continuous contour line when viewed from above.

[0003] The sheets are often provided with a bevel on one or more sides. The beveling or rounding of glass edges in general is described, for example, in JP 2002 160147 A, WO 02 / 45909 A1, or WO 2014 / 035946 A1.

[0004] When beveling an edge, a bevel is usually applied to the surface by grinding and polishing. The bevel runs parallel to the outer edge. The original sheet thickness is thereby reduced to a value of typically 20% to 80%. The remaining edge is referred to as the residual edge. Faceting creates an exposed edge that is still sensitive to impact even after the bevel has been applied. This reduces the mechanical strength of the workpiece.

[0005] The material removal during the production of the facet also changes the profile of the remaining edge. The remaining edge must therefore be ground down and given a new profile. This additional material removal also affects the rounding. The material removal leads to a shortening of the corner surface and a reduction in the corner angle, so that the radius of the rounding no longer flows completely into the remaining edge. The edge line at the transition from the corner surface to the remaining edge surface not only exhibits a discontinuity in the top view, but also a horizontal and vertical offset in the side view of the panel. The aesthetic impression is significantly impaired.

[0006] For beveling and grinding the residual edge, automatic machines are usually available that perform both machining processes in direct sequence through a linear arrangement of the required grinding and polishing tools. In such automatic machines, the workpiece is moved in a straight line past the grinding and polishing tools. Grinding of the residual edge can be optionally selected or deselected by advancing or retracting the corresponding tool positions toward or from the workpiece edge.

[0007] JP 2002160147 A describes an edge grinding process that uses a grinding wheel with a concave cross-section and made of a plastic material with embedded fibers and abrasive grains. This gives the glass edges a rounded profile.

[0008] WO 02 / 45909 A1 describes a facet grinding wheel with a cup-shaped grinding wheel body with a central bore, the cup rim of which is designed as a grinding ring. A second grinding ring is arranged concentrically inside the cup space, which supports the developing facet when grinding flat facets on glass panes, particularly glass-ceramic panes. This prevents rounded entry and exit corners at the end of the fracture edge.

[0009] WO 2014 / 035946 A1 discloses a four-step process for processing broken edges of glass plates. Rotating grinding wheels are used to first create chamfers on the edges, which also removes material from the broken edge. In a subsequent process step, the remaining front edge is machined. Finally, a polishing process is performed with a polishing roller, which can also round off sharp corners and edges.

[0010] The object of the invention is to provide a faceted glass or glass-ceramic plate whose circumferential contour line runs as evenly as possible, particularly in the transition from the corner surface to the remaining edge surface. It is also an object of the invention to provide a corresponding method for producing such a glass or glass-ceramic plate.

[0011] This object is achieved with a glass or glass ceramic plate having the features of claim 1.

[0012] The glass or glass ceramic plate is characterized in that for the distances z E and z R z R < z E applies, that between the remaining edge surface and the corner surface there is provided a transition surface with a profile P Ü which differs from the profiles PE and PR, wherein the transition surface has at least three corners, two of which corners lie on the lower edge, and that the transition surface forms a first boundary line with the corner surface and a second boundary line with the remaining edge surface, wherein a third corner point of the transition surface lies at the intersection point of the first boundary line and the second boundary line.

[0013] A profile is defined as the contour of an edge surface characterized by two parameters, VK and HK. The vertical contour VK is a contour lying in the yz-plane, and the horizontal contour HK is a contour lying in the xy-plane. The contours VK and HK have straight lines and / or curvatures with corresponding radii.

[0014] The xyz coordinate system serves only to better describe the invention and does not specify the orientation of the glass or glass-ceramic plate in space, e.g., in an installation situation. This also applies to the terms "bottom" and "top."

[0015] The plate has a contour line K, which is the outer circumference of the plate in plan view. The contour lines KR and KE are sections of this contour line K.

[0016] It has been shown that the corner angle W can be increased compared to the prior art by providing a transition surface. The corner angle W is defined by the contour line KE. The contour line K is thus smoothed out at the transition from the corner surface to the remaining edge surface, which improves the aesthetic appearance of the glass or glass-ceramic panel. Furthermore, the course of the contour line K at the transition from the corner surface to the remaining edge surface can be positively influenced.

[0017] Preferably, the transition surface is configured such that the intersection point of the boundary lines in the z-direction lies between the contour lines KR and KE. In this embodiment, a section of the second boundary line forms a section of the contour line.

[0018] Preferably, the transition surface is configured such that the intersection point lies on or below the contour line KE, which has the advantage that a section of the second boundary line connects the contour lines KR and KE. If the intersection point lies on the contour line KE, the connection between the contour lines KR and KE is defined exclusively by the second boundary line. If the intersection point lies below the contour line KE, the connection between the contour lines KR and KE is formed by the second boundary line and a section of the boundary line of the corner surface.

[0019] Preferably, at least one of the profiles PE or PR is a round profile in the z-direction with at least one radius of curvature. Such a profile is referred to as a C-profile. The contour line of a C-profile is the apex line.

[0020] C-profiles have the advantage that the transition to the two upper surfaces is not sharp-edged, thus improving the handling of the panels. They also reduce the panels' sensitivity to impact.

[0021] Preferably, both profiles PE and PR are round profiles in the z-direction with at least one radius of curvature.

[0022] These C-profiles are preferably symmetrical to the centerline of the respective panel sections in the xy plane. Symmetric C-profiles are characterized by good edge strength.

[0023] Preferably, the profile PE has a contour VK E lying in the xz plane and a contour HK E lying in the xy plane, and the profile P Ü has a contour VK Ü lying in the yz plane and a contour HK Ü lying in the xy plane. It is preferred that the contour VK Ü is identical to the contour VK E. The advantage of this correspondence between the contours VK Ü and VK E is that it can simplify the grinding process.

[0024] Preferably, the contour HK Ü has a radius of curvature R Ü.

[0025] Preferably, the radius of curvature R Ü ≥ RS , where RS is the radius of a grinding tool, in particular a grinding wheel, that can be used to machine the edge surfaces.

[0026] Instead of so-called C-profiles, other profiles can also be used, such as profiles with a flat surface with adjacent chamfers. Such profiles are referred to as V-profiles. V-profiles are preferably symmetrical to the centerline of the respective panel sections in the xy plane. The centerline forms the contour line.

[0027] Preferably, the profile PE has a contour VK E and a contour HK E, wherein the contour VK E is equal to a contour VK 1 of a profile P 1 of an edge surface.

[0028] The following plate parameters are preferred: D 2 mm to 5 mm, especially 4 mm DR 2.0 mm to 3 mm, especially 2.5 mm R 1.5 mm to 30 mm, especially 5 mm γ 80° to 100°, especially 90° Grinding wheel radius R S 10 mm to 150 mm, especially 130 mm R 1 1.75 mm to 6 mm RR 1.75 mm to 6 mm

[0029] The glass-ceramic plate preferably has a glassy surface zone at least on the corner surface. The glassy surface zone preferably extends at least over the entire corner surface.

[0030] Preferably, the corner surface and the transition surface have a glassy surface zone.

[0031] Further preferably, the glass-ceramic plate has a glassy surface zone on at least the corner surface and the transition surface. Preferably, the glassy surface zone extends at least over the entire corner surface and over the entire transition surface.

[0032] The amorphous (glassy) surface zone of a LAS glass-ceramic is understood to be a zone or layer directly on the glass-ceramic surface which, in contrast to the interior, i.e. the structure below this surface layer, does not have the HQMK (or other) crystals which are typically on average 20 nm to 100 nm in size, but is predominantly amorphous. For HQMK or KMK (keatite solid solutions) as the main crystal phase, the essentially amorphous surface zone comprises a maximum of 10 vol.% crystals, i.e. at least 90 vol.% of the surface zone consists of a glassy matrix (detectable by grazing X-ray diffraction). The amorphous surface region particularly preferably comprises less than 1 vol.% crystals. In contrast, crystals in the essentially crystalline interior of the glass-ceramic article make up at least 70 vol.%, preferably at least 80 vol.%, particularly preferably at least 90 vol.%.

[0033] This layer can be detected either by grazing X-ray diffraction or by cross-sectional preparation and electron diffraction in a transmission electron microscope (TEM) or indirectly in a scanning electron microscope (SEM).

[0034] For the SEM examination, the cross-section is first chemically etched with dilute hydrofluoric acid. Hydrofluoric acid attacks the glass phase of the LAS glass-ceramic much more strongly than the HQMK / KMK crystals. This enhances the contrast of the crystals, and the grain boundaries of the crystals are visible in the SEM, allowing the expert to distinguish between the crystalline interior and the glassy surface area based on the structural differences visualized by X-ray diffraction and SEM / TEM.

[0035] The thickness of the glassy surface zone is in the range from 50 to 5000 nm, preferably from 250 to 3000 nm and particularly preferably from 300 to 1500 nm.

[0036] A transition zone mediates between the glassy edge region and the crystalline interior of the glass-ceramic article, with the number or proportion of crystals relative to the glassy matrix increasing towards the crystalline interior. The transition zone between the glassy edge region and the crystalline interior of the article is advantageously as small as possible. Due to the process according to the invention, it is preferably kept less than 100 nm in thickness. Keeping the transition zone between the glassy edge region and the crystalline interior as small as possible increases the transmittance of the finished article. The sharper the transition between the two layers, the higher the transmittance.

[0037] In this glassy surface zone, the glass ceramic not only has a high degree of transparency, but also a high degree of mechanical strength, which is particularly advantageous when used as a cooking surface.

[0038] Such high-strength, highly transparent glass-ceramic articles can be produced by a specific combination of nucleation and crystallization temperatures with specific residence times and a rapid cooling rate. Improvements in the above-mentioned properties are possible for starting glasses of different compositions. The advantages in terms of transparency and strength are particularly pronounced in lithium aluminosilicate glass-ceramics (LAS glass-ceramics).

[0039] A glass or glass ceramic plate with a top surface and a bottom surface lying in the xy plane in an orthogonal xyz coordinate system, with a circumferential lower edge and a circumferential upper edge, with at least one first edge surface and at least one second edge surface, the edge surfaces forming an angle γ with one another, and with a curved corner surface of a corner E connecting both edge surfaces, which has a radius of curvature R with a center point M, a contour line KE and a corner angle W, the top surface having a facet with a facet surface on at least one of the two edge surfaces, as a result of which a residual edge surface with a thickness DR and a contour line KR is formed on the edge surface, is characterized in that 0.9 • R ≤ AR ≤ 1.1 • R applies for a distance AR of the contour line KR from the center point M.

[0040] Preferably 0 , 95 · R ≤ A R ≤ 1 , 05 · R .

[0041] According to a first embodiment, the object is also achieved by a method for producing a glass or glass ceramic plate with the following steps in the following order: a) Providing a plate blank with a first top surface lying in an xy-plane in an orthogonal xyz coordinate system and a second top surface lying in a parallel xy-plane, and with at least one first edge surface and a second edge surface which form an angle γ with each other, b) Pre-grinding at least the edge surfaces, wherein at least between the edge surfaces a corner surface with a corner radius R and a corner angle β of the grinding contour is produced, wherein on at least one edge surface an edge strip with the width B ZG is machined which adjoins the corner surface and extends over the edge surface in the x- or y-direction, and wherein at least the edge surfaces, the corner surface and the edge strip are provided with a profile P 1, c) Faceting a top surface, wherein at least one,a facet is produced which tapers towards the edge surface having the edge strip and the edge surface is reduced to a residual edge surface, d) grinding the residual edge surface, whereby the residual edge surface is provided with a profile PR.

[0042] The advantage of this manufacturing process is that it creates an edge strip extending across the edge surface in the y-direction, so that in process step d) when grinding the remaining edge, the corner surfaces are not shortened to the extent that is the case with conventional processes. The corner angle W can be tapered longer, which improves the aesthetic impression. The same applies to edge strips extending in the x-direction.

[0043] In the production of a glass ceramic plate, a plate blank made of glass ceramic or glass can be provided in step a).

[0044] Preferably, process step a) starts with a glass blank. In this embodiment of the process, the ceramization of the glass blank takes place at a later time and can preferably be carried out after all process steps a) to d).

[0045] It is particularly preferred to carry out the ceramization before or after faceting in process step c).

[0046] The later in the process the ceramization is carried out, the larger the part of the surface of the plate that has a glassy surface zone.

[0047] When machining the edge strip, a straight edge strip section and a transition section with a transition section surface are preferably produced, with the transition section surface merging into the corner surface. Providing a transition section at both ends of the straight edge strip facilitates the production of the edge strip. The continuous course of the transition section prevents sharp edges on the edge strip.

[0048] Preferably, the transition section surface is produced with a radius of curvature R Ü.

[0049] Preferably, the radius of curvature R Ü is selected such that R Ü ≥ RS, where RS is the radius of a grinding tool intended for pre-grinding.

[0050] When machining the edge strip, the corner angle β of the grinding contour is preferably set to 60° ≤ β ≤ 90°.

[0051] It has been shown that the corner angle β of the grinding contour influences the length in the y-direction of the transition surface, as well as the shape of the transition surface and the offset VY of the contour lines KR and KE in the y-direction and x-direction, respectively. The smaller the value β, the smaller the transition surface and thus also the value VY. However, the angle β must not be chosen too small, as this would reduce the angle W too much.

[0052] Preferably, the grinding in process step d) in the region of the straight edge strip section of the edge strip is accompanied by a material removal B AT, where 0.1 · B ZG ≤ B AT ≤ 2 · B ZG . Preferably, 0.5 · B ZG ≤ B AT ≤ 1.5 · B ZG .

[0053] It has been shown that the amount of material removal B AT influences the length and size of the transition surface. It is preferable to select the amount of material removal B AT equal to the amount of material addition B ZG.

[0054] The width B ZG is preferably 0.2 mm to 2 mm, in particular 0.5 mm to 1 mm.

[0055] The object is achieved according to a second embodiment with a method for producing a glass or glass ceramic plate with the following steps in the following order: a) Providing a plate blank with a first top surface lying in an xy-plane in an orthogonal xyz coordinate system and a second top surface lying in a parallel xy-plane, with at least one first edge surface and a second edge surface which together form a corner with an angle γ and with a width B 1 and a length L 1 , wherein a material allowance of the width B ZG is taken into account on at least one edge surface, b) Pre-grinding at least the edge surfaces, wherein at least the edge surfaces are provided with a profile P 1 , c) Faceting a top surface, wherein at least one facet tapering to the edge surface having the material allowance B ZG is produced and the edge surface is reduced to a residual edge surface, d) Smoothing the residual edge surface, wherein the residual edge surface is provided with a profile PR, e) Smoothing the at least one corner,whereby a corner surface with a corner radius R and a corner angle of the grinding contour β is produced between the edge surfaces. ,

[0056] As in the first embodiment of the method, process step a) can start with a plate blank made of glass or glass ceramic. If a glass plate is provided for the production of a glass ceramic plate, the ceramization can be carried out after all process steps a) to e), as in the first embodiment of the method.

[0057] The key difference of the manufacturing process according to the second embodiment is that the corner surface(s) are manufactured at the end of the process. The advantage of this process is that, in process step b), a simplified edge grinding process can be used, in which two opposing edges are machined simultaneously, in a straight line, in a continuous process. Such processing machines are widely used in the glass industry for the simple processing of rectangular, flat panes. A defined corner radius is not added.

[0058] In this second embodiment, as in the first embodiment, a transition surface is also created because the profiles PE and PR have contour lines KE and KR offset in the z-direction.

[0059] By taking into account the material allowance B ZG, the dimension B 1 and / or the dimension L 1 has a corresponding excess compared to the final dimensions B and / or L, which is at least partially removed during the subsequent process steps by edge machining in order to finally obtain the final dimensions.

[0060] Preferably, the material allowance B ZG is taken into account in such a way that at least B 1 = B 2 + n · B ZG and / or L 1 = L 2 + n · B ZG with n = 1 or n = 2 applies. In this case, n = 1 is chosen if a facet is only applied to one edge surface.

[0061] If facets are provided on two opposite edge surfaces, n = 2 is chosen.

[0062] Preferably, the material allowance with the width B ZG extends over the entire width B 1 and / or over the entire length L 1 .

[0063] Preferably, the grinding in process step d) is accompanied by a material removal B AT, where 0.1 · B ZG ≤ B AT ≤ 2 · B ZG.

[0064] In particular, the grinding in process step d) is carried out with a material removal B AT , where B ZG = B AT .

[0065] Preferably, the method step e) is carried out by means of a grinding tool, wherein the grinding tool is guided around the corner starting from an edge surface until the corner angle β is reached and is then continuously removed over the remaining edge surface.

[0066] The grinding tool follows an S-shaped trajectory curve, whereby the transition surface is worked out in the remaining edge surface as the trajectory curve continuously runs out.

[0067] Preferably, the material allowance of the width B ZG is chosen to be so large that the profile P 1 applied in process step b) is completely replaced by the profile PR in process step d).

[0068] Preferably, the profile PR is manufactured as a profile with a radius of curvature RR.

[0069] Preferably, the PR profile is manufactured as a symmetrical profile.

[0070] Preferably, the profile of the corner radius PE is manufactured according to the profile P 1 of the adjacent edge surface.

[0071] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. They show: Figure 1a shows a plan view of a plate blank according to process step a) according to the first and second embodiment of the process, Figure 1b shows a partial section along the line I-II in Figure 1a through the blank according to Fig. 1a, Figure 2a the top view of a plate blank after carrying out the process step b) according to the first embodiment of the method, Figure 2b a section through the machined blank along the line I-II in Figure 2a , Figure 2c an enlarged view of the upper edge area of ​​the machined blank from Figure 2a according to a first embodiment, Figure 2 shows an enlarged view of the upper left corner area of ​​the machined blank from Figure 2a according to a further embodiment, Figure 2e shows an enlarged view of the upper left corner area of ​​the machined blank from Figure 2a with grinding wheel for carrying out process step b), Figure 2 fine perspective view of a corner area of ​​the Figure 2ashown blank, Figure 3a the top view of the machined blank after faceting according to process step c) according to the first embodiment of the method, Figure 3b a section through the machined blank along the line I-II in Figure 3a , Figure 3c a perspective view of a corner area of ​​the machined blank according to Figure 3a , Figure 4a a plan view of the finished plate after grinding according to process step d) according to the first embodiment of the method, Figure 4b an enlarged view of the upper right corner area of ​​the plate from Figure 4a , Figure 4c a section through the plate along the line I-II in Figure 4b , Figure 5 a section through a blank and a finished plate to explain the width B ZG , Figure 6 a perspective view of a corner of a glass or glass ceramic plate according to Fig. 4a, Figure 7 a perspective view of a corner of a plate according to a further embodiment, Figure 8 a perspective view of a corner of a plate according to a further embodiment, Figure 8a an enlarged view of the corner from Fig. 7 , Figure 9 a perspective view of a corner of a plate according to a further embodiment, Figure 10 a perspective view of a corner according to a further embodiment, Figures 11 to 13 top views of a blank and a finished plate having two facets, each after the method steps b), c) and d), according to the Figures 2a , 3a and 4a, Figure 14 a perspective top view of a corner of a plate with two facets, Figure 15 a perspective view of a corner of a plate with two facets according to a further embodiment, Figure 16 a perspective view of a corner of a plate according to the prior art, Figure 17 a perspective view of a corner of a plate according to the Figure 9 , Figure 18a a perspective view of a corner of a plate with a view of the underside according to the prior art, Figure 18b a plan view of the underside of the Fig. 18a shown plate according to the prior art, Figure 19a a perspective view of a corner of a plate with a view of the underside, Figure 19b a plan view of the underside of the plate shown in Fig. 19ashown plate, Figure 20a the top view of a plate blank after carrying out the process step b) according to the second embodiment of the method, Figure 20b a section through the machined blank along the line I-II in Figure 20a , Figure 21a the top view of the machined blank after faceting according to process step c) according to the second embodiment of the method, Figure 21b a section through the plate along the line I-II in Figure 21a , Figure 22a a plan view of the plate after grinding according to process step d) according to the second embodiment of the method, Figure 22b a section through the plate along the line I-II in Figure 22a, Figure 23 a plan view of the finished plate after sanding according to method step e) according to the second embodiment of the method, and Figure 24 a perspective view of a corner to explain method step e) according to the second embodiment of the method.

[0072] In the Figure 1a 1 shows a top view of a blank 200, which may be made of glass or glass ceramic. The blank 200 consists of a rectangular plate with a thickness D, a width B 1 and a length L 1 as well as opposite first edge surfaces 210 and opposite second edge surfaces 220, all of which are unmachined. The blank 200 has a first top surface 2 and a second top surface 3, which are arranged parallel to each other and lie in xy planes (see Figure 1b). In a built-in situation, e.g. in a hob, the first top surface 2 can form the top side and the second top surface 3 can form the bottom side.

[0073] In Figure 2a The top view of the blank 200 is shown after a first edge processing has been carried out. This is the pre-grinding according to process feature b), whereby between the edge surfaces 210 and 220 a corner surface 230 with a corner radius R and a corner angle of the grinding contour β has been produced (see Figure 2c ).

[0074] Since each edge processing operation involves material removal, the width and length of the blank 200 have decreased. The length L 1 of the blank 200 has been shortened to the length L, which corresponds to the final dimension of the finished plate 1, because the length L is not changed by the subsequent process steps.

[0075] The width B 1 has been reduced to the width B 3. By machining an edge strip 240, the width B 3 is composed of a width B 2 and a width B ZG of the edge strip 240. The width B ZG refers to the material allowance that is at least partially removed again after process step c) in the last process step d). This material removal is referred to as B AT, which in the Figures 4a and 4b is shown. The final dimension B is only reached after process step d).

[0076] During edge processing according to process step b), all edge surfaces, i.e. the edge surfaces 210 and 220 as well as the 4 corner surfaces 230 are provided with a profile P 1. As shown in the sectional view of the Figure 2b As can be seen, it is a round profile with a radius of curvature R 1 (see also Fig. 2f and Fig. 5), which is referred to as a C-profile. In the illustration shown here, the C-profile is symmetrical to the center line MP of the blank 200.

[0077] In the Figure 2c the upper edge area of ​​the machined blank 200 is made of Figure 2a Enlarged view. The first edge surfaces 210 each merge into a corner surface 230 of the corner E, which extends over the corner angle β. In the embodiment shown here, the corner angle β is 90°, which corresponds to the angle γ between the first edge surfaces 210 and the second edge surfaces 220.

[0078] The corner surfaces 230 of the corners E merge at the tangent point 248 into the edge strip 240, which consists of a straight edge strip section 242 and two transition sections 244 with transition section surfaces 250 adjacent to the straight edge strip section 242. The connecting line 243 connects the two tangent points 248.

[0079] The transition sections 244 have a radius of curvature R Ü , which can be equal to the radius RS of the grinding wheel 300 used for process step b), as shown in the Figure 2e is shown.

[0080] In the Figure 2d A further embodiment is shown in which the corner angle β is approximately 70°. The edge strip 240 thus extends into the corner area and shortens the adjacent corner surface 230.

[0081] The perspective representation in Figure 2f shows a corner E of the machined blank 200 according to the Figure 2c . Since the blank 200 was provided with a circumferential C-profile P 1, the apex lines of the surfaces 210, 220, 230 form a closed contour line K.

[0082] The Figure 3ashows a machined blank 200 in plan view after process step c), in which a facet 40, which has a facet surface 42 and a facet edge 44, has been produced on the second edge surface 220, on which the edge strip 240 is located. The corresponding cross section in the edge region of the blank 200 is shown in the Figure 3b In this process step, the width of the second edge surface 220 has decreased to the remaining edge surface 220a.

[0083] The perspective representation in the Figure 3c shows a corner E of the machined blank 200 according to the Figure 3a .

[0084] The Figure 4a shows a top view of the finished plate 1 with the edge surfaces 10, 20, 60 and the final dimensions B and L after process step d), in which the remaining edge surface 220a was ground. In process step d), the remaining edge surface 60 was provided with the profile PR, which - like the Figure 4cshows - is also a C-profile. The ground residual edge surface 60 has a thickness DR.

[0085] During grinding, material was removed from the edge strip 240, which is characterized by the width B AT (see also Figure 4b ).

[0086] How the material removal should preferably be determined is described in Figure 5 which shows a section through a blank 200 in combination with a section through a finished plate 1. Figure 5 shows the blank 200 with the second edge surface 220 after process step b) and the finished plate with the remaining edge surface 60 after process step d), ie after grinding the remaining edge.

[0087] Profile P 1 is a C-profile, just like profile PR . Profiles P 1 and PR have the corresponding radii R 1 and RR . The contour lines of profiles P 1 and PR are vertex lines S 1 and SR . P h1 and P h2 denote the profile heights in the x-direction.

[0088] ZR denotes the distance of the contour line KR , which corresponds to the vertex line SR of the remaining edge surface 60, from the circumferential lower edge 100 in the xy plane of the second upper side surface 3. Z 1 denotes the distance of the contour line K 1 , which corresponds to the vertex line S 1 of the edge surface 10, from the circumferential lower edge 100. ZE denotes the distance of the contour line KE , which corresponds to the vertex line SE of the corner surface 30, from the circumferential lower edge 100.

[0089] The material allowance of the width B ZG is calculated as follows: B ZG ≥ P h 1 − P h 2 wobei P h 1 = R 1 − R 1 2 − z 1 und P h 2 = R R − R R 2 − z R ist .

[0090] B ZG is preferably at least wide enough so that the profile PR of the residual edge surface 60 lies within the profile P 1 of the pre-grinding.

[0091] The material removal of the width B AT is preferably B ZG ≤ B AT , in particular B AT = B ZG and influences the value VY , ie the offset of the contour line KR to the contour line KE , as shown in the Figure 6 can be seen.

[0092] The Figure 6 shows a perspective view of a corner E of a glass or glass ceramic plate 1 after all process steps a) to d) have been carried out.

[0093] The glass ceramic plate 1 has the circumferential lower edge 100 and the circumferential upper edge 110. The facet 40 is delimited by the upper edge 21 and the facet edge 44. The corner surface 30 of the corner E is delimited by the boundary line 33, the upper edge 31, the lower edge 32, and the boundary lines 34 and 52.

[0094] At least the corner surface 30 and the transition surface 50 have a glassy surface zone.

[0095] The explanations to the Figure 6 The left corner E of the plate 1 shown also applies accordingly to a second, right corner of the plate 1 as well as to further corners of a plate 1 if further facet surfaces 40 are provided.

[0096] The parameters were chosen as follows: D = 4 mm, DR = 2.5 mm, R = 5 mm, γ = 90°, β = 90°, B ZG = 0.5 mm, B AT = 0.5 mm, P 1 and PR are each a C-profile with the radii of curvature R 1 = 3 mm and RR = 3 mm, respectively. Facet 40 has a facet angle α of 8.5° and a facet width of 10 mm. The angles γ and β refer to the center point M.

[0097] The parameters of the corresponding blank correspond to the Figure 2c shown top view of a blank 200.

[0098] In the Figure 6The horizontal contour HK 1 and the vertical contour VK 1 of the profile P 1 are shown, as are the vertical contour VK E and the horizontal contour HK E of the profile PE. The profile PR comprises the horizontal contour HK R and the vertical contour VK R. The transition surface 50 has the profile P Ü with the contours VK Ü and HK Ü. The profiles P 1 , PE and PR are C-profiles with the contour lines K 1 , KE and KR , which are identical to the vertex lines S 1 , SE and SR.

[0099] It can be seen that the angle γ = 90° has decreased to the angle W = 78.8°, with the vertical offset Vz = 0.75 mm and the horizontal offset VY = 5.95 mm. The corner angle W is defined by the contour line KE.

[0100] The residual edge surface 60 has a transition surface 50, which has a profile P Ü that deviates from the profile PR. The transition surface 50 is a remnant of the transition section 244 that was not machined when the residual edge was ground. As the material removal B AT is increased, the size of the transition surface 50 also decreases. With increasing material removal, both the corner angle W and VY change, as shown in the Figure 7 The material removal is 0.6 mm, so the angle W is reduced to 73.9°. VY is 1.17 mm.

[0101] In the Figure 8 Another embodiment is shown in which the corner angle β of the grinding contour was chosen to be β = 82° (see also Figure 2d ). The remaining parameters of plate 1 correspond to the Figure 6 .

[0102] The transition area 50 in the Fig. 8 is just like in the Figure 6triangular and has corners 58a, b, c. The transition surface 50 is bounded by the lower edge 56 and the two boundary lines 52 and 54, which gives the transition surface 50 a "sail-shaped" appearance. The two contour lines KE and KR are connected by the connecting contour line KV, which is formed from a section of the boundary line 54 and a section of the boundary line 34. The boundary lines 34, 54, and 52 meet at an intersection point 59. The contour line KV is thus largely determined by the shape of the transition surface 50.

[0103] The intersection point 59 lies between the contour lines KE and KR . The length of the contour line KV is characterized by the horizontal offset VY, as shown in Fig. 8a is illustrated, where the offset VX and the offset are also shown.

[0104] In the Figure 9Another embodiment of a plate 1 is shown, the angle β is 78.8°. The other parameters correspond to the plate from the Figure 8 . Due to the reduction of the corner angle β of the grinding contour, the intersection point 59 has moved upwards and in this embodiment lies on the contour line KE .

[0105] In the Figure 10 Another embodiment is shown, in which the radius R of the corner angle is 10 mm. The angle β of the grinding contour is 82.1°, as is the angle W. It can be seen that the transition surface 50 has the same shape as in Figure 9 . In the embodiment of the Figure 10 the offset VY is 1.33 mm, while the offset VY in the Figure 9 is 0.95 mm.

[0106] The Figures 11 to 13 correspond to the Figures 2a , 3a and 4a and concern a plate with two facets 40.

[0107] In the Figure 11The blank 200 is shown, which has an edge strip 240 on an edge surface 220 and on an edge surface 210. The angle β of the grinding contour is 90°. The top view of the plate in Figure 11 shows the blank after process step b). The material allowances B ZG are the same for both edge strips 240. The length L 2 denotes the length without the material allowance, and the length L 3 denotes the length of the blank after pre-grinding.

[0108] In the Figure 12 The blank is shown after faceting according to process step c). The two facets 40 adjoin each other at corner E.

[0109] In the Figure 13 The finished plate 1 is shown after carrying out process step d). A perspective view of the corner E of the Figure 13 is in the Figure 14can be seen. Due to the double beveling, the corner angle W has been reduced to 67.6°. The material allowance is 0.5 mm, the material removal is 0.5 mm, and the grinding wheel radius R Ü is 130 mm. The horizontal offset VY is the same on both facets at 5.93 mm.

[0110] In the Figure 15 another embodiment of a plate 1 with two facets 40 is shown. While in the Figure 14 the angle β of the grinding contour is 90°, the angle β in the embodiment according to the Figure 15 at 67.6°. The corner angle W is also 67.6°.

[0111] The Figure 16 shows a plate 1' according to the prior art and the Figure 17 a plate 1, as in Figure 9 In both Figures 16 and 17The distance AR was drawn, which denotes the distance of the contour line KR from the center point M of the corner E. Both plates 1 and 1' have the same dimensions D, DR, R, ZE, ZR, P 1, PE, PR. It can be seen that the angle W of plate 1, at 78.8°, is significantly larger than the angle W of plate 1' with W = 61.8° according to the state of the art.

[0112] Another significant difference is the distance AR of the edge line KR of the residual edge surface 60 from the center point M of the corner E, which corresponds to the corner radius R of the corner E. By grinding the residual edge surface 60 according to the prior art methods, the distance AR is significantly reduced by the associated material removal B AT, since the material allowance B ZG is not applied separately as an edge strip, which has a corresponding influence on the angle W. In the method according to the invention, the targeted material addition in the form of the edge strip 240 and the subsequent material removal B AT with preferably B AT = B ZG ensures that the distance AR = R.

[0113] The following table shows the data of the plates from the Figures 6 , 7 , 8 , 9 , 10 and 14 to 16 summarized: D [mm] DR [mm] R [mm] γ [°] β [°] B ZG [mm] B AT [mm] [mm] VY [mm] W [°] Fig. 6 4 2,5 5 90 90 0,5 0,5 0,75 5,95 78,8 Fig. 7 4 2,5 5 90 90 0,5 0,6 0,75 1,17 73,9 Fig. 8 4 2,5 5 90 82 0,5 0,5 0,75 1,28 78,8 Fig. 9 4 2,5 5 90 78,8 0,5 0,5 0,75 0,95 78,8 Fig. 10 4 2,5 10 90 82,1 0,5 0,5 0,75 1,33 82,1 Fig. 14 4 2,5 5 90 90 0,5 0,5 0,75 5,95 67,6 Fig. 15 4 2,5 5 90 67,6 0,5 0,5 0,75 0,95 67,6 Fig. 16 4 2,5 5 90 90 0 0,5 0,75 0,41 61,8

[0114] In the Fig. 18a The underside of a corner E of the plate 1' is shown in perspective according to the prior art. Fig. 18b shows the top view of the Fig. 18a shown plate 1'. The three surfaces 10, 30 and 60 in the edge area of ​​plate 1' are clearly visible.

[0115] The Fig. 19a and 19b show the Fig. 18a and 18b corresponding representations for a plate 1 according to the invention. The bottom views differ by the additional transition surface 50.

[0116] In the Figures 20a to 24 the method steps according to the second embodiment of the method are shown.

[0117] The Fig. 1also illustrates the initial situation according to process step a) for this second embodiment of the process, with the difference that a material allowance B ZG was taken into account for the width B 1 of the blank.

[0118] The Fig. 20a shows the top view of the plate blank 200 after performing process step b) according to the second embodiment of the method. The material allowance B ZG extends over the entire length L. Due to the pre-grinding of the edge surfaces, the width B 1 has been reduced to the width B 3 .

[0119] The Figure 20b shows a section through the machined blank 200 along the line I-II in Figure 20a so that profile P 1 can be seen.

[0120] The Figure 21a shows the top view of the machined blank after faceting according to process step c). The sectional view along the line I-II in Fig. 21a shows the Fig. 21b .

[0121] The Figure 22a shows the top view of the plate after grinding the remaining edge surface 60 according to process step d) and Figure 22b shows the section through the plate along the line I-II in Figure 22a so that the PR profile can be seen.

[0122] The Figure 23 shows a top view of the finished plate 1 after sanding the corner E according to process step e).

[0123] In the Fig. 24 The dashed line shows the movement path 400 of a grinding tool (not shown) for producing the rounding of the corner E and the transition surface 60. In the illustration shown here, the movement curve is essentially S-shaped. List of reference symbols

[0124] 1Glass or glass-ceramic plate 1'Glass or glass-ceramic plate according to the state of the art 2First top surface 3Second top surface 10first edge surface 20second edge surface 21upper edge 30Corner surface 31Upper edge 32Lower edge 33Boundary line 34Boundary line 40Facet 42Facet surface 44Facet edge 50Transition surface 52First boundary line 54Second boundary line 56Lower edge line 58a,b,cCorners of the transition surface 59Intersection point 60Remaining edge area 100circumferential lower edge 110circumferential upper edge 200 blanks 210first edge surface 220second edge surface 220aremaining edge surface 230Corner area 240Edge strip 242Straight edge strip section 243Connecting line 244Transition section 248Tangent point 250Transition section surface 300Grinding tool, grinding wheel 400Movement path of the grinding tool B Width Final dimension of the plate 1 B 1 Width of the blank B 2 Width of the blank without material allowance B 3 Width of the blank after pre-grinding B ZG Width of the material allowance B AT Width of the material removal LLength final dimension of plate 1 L 1 Length of the blank L 2 Length of the blank without material addition L 3 Length of the blank after pre-grinding WECorner angle αFacet angle βCorner angle of the grinding contour γAngle between first edge surface 10, 210 and second edge surface 20, 220 P 1 Profile PR Remaining edge profile PE Corner profile P Ü Profile of the transition surface R 1 Radius of curvature of the profile P 1 RR Radius of curvature of the profile PR HK 1 horizontal contour of profile P 1 VK 1 vertical contour of profile P 1 HK R horizontal contour of profile PR VK R vertical contour of profile PR HK E horizontal contour of profile PE VK E vertical contour of profile PE HK Ü horizontal contour of profile P Ü VK Ü vertical contour of profile P Ü K Contour line K 1 Contour line of the first edge surface KE Contour line of the corner KR Contour line of the remaining edge KV Connecting contour line RE Corner radius RS Radius of the grinding wheel R Ü Radius of the transition surface section S 1 first vertex line S 2 vertex line SR vertex line of the remaining edge SE vertex line of the corner EP h1 profile height in x-direction P h2 profile height in x-direction VY horizontal offset of the contour lines KE and KRVZ vertical offset of the contour lines KE and KRVX offset of the contour lines KE and KR in x-direction DD Thickness of the plate DR Thickness of the plate at the remaining edge area MCenter point of the corner angle WMP Center line of the plate z 1 Distance of contour line K 1 from bottom edge 100 z R Distance of contour line KR from bottom edge 100 z E Distance of contour line KE from bottom edge 100 AR distance KR from M corner

Claims

1. Glass or glass ceramic plate (1) having a first upper surface (2) lying in the xy plane in an orthogonal xyz coordinate system and a second upper surface (3), having a circumferential lower edge (100) and a circumferential upper edge (110) having at least one first edge surface (10) and at least one second edge surface (20) which together form an angle γ, and having a corner surface (30) connecting both edge surfaces (10, 20), having a profile PE and having a corner angle W, wherein the first upper surface (2) has a facet (40) having a facet surface (42) on at least one of the two edge surfaces (10, 20), whereby a remaining edge surface (60) having a profile PR is formed on the edge surface (10, 20), and wherein the profile PR has a contour line KR with a distance zR from the lower edge (100), and the profile PE has a contour line KE which has a distance zE from the lower edge (100), characterized in that for the distances zE and zR: zR < zE, and in that between the remaining edge surface (60) and the corner surface (30) a transition surface (50) having a profile PÜ different from the profiles PE and PR is provided, wherein the transition surface (50) has at least three corners (58a,b,c), of which two corners (58b,c) lie on the lower edge (100), and in that the transition surface (50) forms a first boundary line (52) having the corner surface (30) and a second boundary line (54) having the remaining edge surface (60), wherein a third corner point (58a) of the transition surface (50) lies at the intersection (59) of the first boundary line (52) and the second boundary line (54).

2. Glass or glass ceramic plate (1) according to Claim 1, characterized in that the transition surface (50) is designed such that the intersection (59) of the boundary lines (52, 54) lies in the z-direction between the contour lines KR and KE.

3. Glass or glass ceramic plate (1) according to either one of Claims 1 or 2, characterized in that the transition surface (50) is designed such that the intersection (59) of the boundary lines (52, 54) lies on or below the contour line KE.

4. Glass or glass ceramic plate (1) according to one of Claims 1 to 3, characterized in that the profile PE has a contour VKE lying in the yz-plane and a contour HKE lying in the xy-plane, and in that the profile PÜ has a contour VKÜ lying in the yz-plane and a contour HKÜ lying in the xy-plane, and in that the contour VKÜ is equal to the contour VKE.

5. Glass or glass ceramic plate (1) according to one of Claims 1 to 4, characterized in that the profile PE has a contour VKE and a contour HKE and the contour VKE is equal to a contour VK1 of a profile P1 of an edge surface (10, 20).

6. Method for producing a glass or glass ceramic plate (1) having the following steps in the following order: a) providing a plate blank (200) - having a first upper surface (2) lying in an xy plane in an orthogonal xyz coordinate system and a second upper surface (3) lying in a parallel xy plane, and - having at least one first edge surface (210) and one second edge surface (220) which together form an angle γ, b) pre-grinding at least the edge surfaces (210, 220), - wherein at least one corner surface (230) having a corner radius R and a corner angle β of the grinding contour is produced between the edge surfaces (210, 220), - wherein an edge strip (240) having the width BZG, which borders on the corner surface (230) and extends over the edge surface (210, 220) in the x- or y-direction, is machined on at least one edge surface (210, 220) and - wherein at least the edge surfaces (210, 220), the corner surface (230) and the edge strip (240) are provided having a profile P1, c) facetting an upper surface (2, 3), wherein at least one facet (40) extending to the edge surface (210, 220) having the edge strip (240) is produced and the edge surface (210, 220) is reduced to a remaining edge surface (60), d) grinding the remaining edge surface (60), wherein the remaining edge surface (60) is provided having a profile PR.

7. Method according to Claim 6, characterized in that when machining the edge strip (240), a straight edge strip section (242) and a transition section (244) having a transition section surface (250) are produced, wherein the transition section surface (250) extends to the corner surface (230).

8. Method according to one of Claims 6 or 7, characterized in that when machining the edge strip (240), the corner angle β of the grinding contour is set to 60° ≤ β ≤ 90°.

9. Method according to one of Claims 6 to 8, characterized in that the grinding in method step d) in the region of the straight edge strip section (242) of the edge strip (240) has a material removal BAT, wherein 0.1 · BZG ≤ BAT ≤ 2 · BZG.

10. Method for producing a glass or glass ceramic plate (1) having the following steps in the following order: a) providing a plate blank (200) - having a first upper surface (2) lying in an xy plane in an orthogonal xyz coordinate system and a second upper surface (3) lying in a parallel xy plane, - having at least one first edge surface (210) and one second edge surface (220) which together form a corner E having an angle γ and - having a width B1 and a length L1, wherein a material allowance of the width BZG is taken into account on at least one edge surface (210, 220), b) pre-grinding at least the edge surfaces (210, 220), - wherein at least the edge surfaces (210, 220) are provided having a profile P1, c) facetting an upper surface (2, 3), - wherein at least one facet (40) extending to the edge surface (210, 220) having the material allowance BZG is produced and the edge surface (210, 220) is reduced to a remaining edge surface (60), d) grinding the remaining edge surface (60), - wherein the remaining edge surface (60) is provided having a profile PR, e) grinding at least one corner E, - wherein a corner surface (230) having a corner radius R and a corner angle of the grinding contour β is produced between the edge surfaces (210, 220).

11. Method according to Claim 10, characterized in that the material allowance of the width BZG extends over the entire width B1 and / or length L1.

12. Method according to one of Claims 10 or 11, characterized in that the grinding in method step d) has a material removal BAT, wherein 0.1 · BZG ≤ BAT ≤ 2 · BZG.

13. Method according to at least one of Claims 10 to 12, characterized in that method step e) is carried out using a grinding tool, wherein the grinding tool (300) is guided around the corner E starting from an edge surface (210, 220) until the corner angle β is reached and is then continuously removed over the remaining edge surface (60).

14. Method according to one of Claims 6 to 13, characterized in that the width BZG is selected to be sufficiently large that the profile P1 of the edge strip (240) is completely replaced by the profile PR in method step d).

15. Method according to one of Claims 6 to 14, characterized in that the profile of the corner radius PE is produced according to the profile P1 of the adjacent edge surface (210, 220).