Patent Application
20220340472
This application is a national stage application of the Patent Cooperation Treaty (PCT) international application titled “Planar Glass Element And Method For Separating A Glass Substrate Into A Plurality Of Such Glass Elements”, international application number PCT/EP2020/077413, filed in the European Patent Office on Sep. 30, 2020, which claims priority to and the benefit of the non-provisional patent application titled “Disc-Shaped Glass Element And Method For Separating A Glass Substrate Into A Plurality Of Such Glass Elements”, non-provisional patent application number DE102019215264, filed in the German Patent Office on Oct. 2, 2019. The specifications of the above referenced patent applications are incorporated herein by reference in their entirety.
The invention relates to a pane-shaped glass element having two opposing side surfaces joined edgewise by a number of edge surfaces, wherein there are provided in the or each edge surface filamentary damages forming side-by-side elongate depressions, and wherein the or each edge surface is oblique to the side surfaces. It further relates to a method of separating a glass substrate into a plurality of such glass elements, in which a perforation formed by a sequence of filamentary damage is created in the glass substrate along an intended cut line by means of a perforation laser, and the glass substrate is subsequently broken along the perforation, the perforation laser being set to impinge the laser beams on the glass substrate at an angle relative to the surface normal of the glass substrate.
A variety of processes and concepts can be used to cut or separate glass or glass elements. Among other things, laser-based processes such as laser filament cutting can be used, especially with regard to complex cutting shapes or high precision requirements.
Laser filament cutting, also known as filamentation, makes use of non-linear optical effects. For this purpose, a suitably selected laser—also referred to below as a “perforating laser”—is used, the focus of which is placed under the glass surface of the glass element to be cut and into the material. Due to the so-called self-focusing, there is local heating in the glass material at the point where the focal point is located, the formation of local stresses and a change in the refractive index. As a result, the initially small volume element acts like a lens, and in its continuation, further such filaments can be generated. If the laser beam is guided over the glass in this process, a so-called filament curtain is created, which acts in the manner of a perforation and can serve as a starting point for a subsequent separation step, for example by breaking. This concept of laser filamentation is known, for example, from US 2013/0126573 A1.
From DE 10 2015 111 491 A1, a pane-shaped glass element of the type mentioned at the beginning is known, in which the lateral separation edge created by the introduced perforation formed by the filamentary damage during the subsequent separation or fracture process is made oblique, i.e. inclined relative to the surface normal. This is achieved by setting the perforation laser used to create the perforation in the glass substrate with its laser beam at an angle or inclination to the surface of the glass substrate. According to the teaching of DE 10 2015 111 491 A1, the resulting inclined or slanted separating or edge surface of the glass element is intended to make it particularly easy to detach inner contours when separating the glass elements, even in the case of complex contours or cutting lines.
The invention is now based on the task of further developing a glass element of the above-mentioned type for particularly good usability in a multitude of possible applications. Furthermore, a particularly suitable method of the above-mentioned type for the manufacture of the glass element is to be specified.
With regard to the glass element, this task is solved according to the invention in that the respective beveled edge surface has, in its region provided with the filamentary damages, a surface roughness with a mean roughness value of at least 0.3 μm, and preferably of at most 2 μm, in a particularly advantageous embodiment of about 1 μm.
The invention is based on the consideration that the beveled edge or rim guide actually provided in the known glass element for reasons of facilitated separation or product separation could be used as a basis for an advantageous further development of the glass element in the sense of an improvement of the product properties for its later use. In particular, it can be taken into account that such a beveled side edge is visually conspicuous and can thus be visually recognized more easily than conventional, “straight” edges during both manual and mechanical further processing. Alternatively or in addition, such a beveled side edge can be made particularly suitable for subsequent bonding. In order to improve the glass element specifically with regard to these two functionalities, i.e. easier optical recognition and/or improved suitability for bonding, the roughness or roughness of the surface in the area of the edge surface or edge surfaces is now provided as a parameter suitable for this.
In particular, it is taken into account that the roughness on the one hand is an indication of the optical detectability. Furthermore, the degree of gloss is a criterion, but also the scattered light (diffusion) due to the typical fracture surface with many small individual surfaces, as glass breaks brittly. In particular, it must be taken into account that normal broken or processed glass edges are often difficult to recognize. The contrast is usually low because it is a transparent material whose surfaces can often also be reflective. In particular, laser modification cutting with the standard process creates high-quality surfaces that are relatively inconspicuous in the direction of the surface normal. This can now be taken into account in the finished glass element in particular by the fact that in comparison with the directly adjacent surface areas of the side surfaces of the glass element, which usually have an extremely low surface roughness, a contrast can be specifically created through the roughness now provided, through which the recognizability can be significantly improved. On the other hand, the intended surface roughness is particularly favorable for bonding, as in this way it is particularly easy to create an intimate material contact with an adhesive.
The demarcation of the “area provided with filamentary damage” from the other areas of the edge surface is preferably carried out on the basis of the criterion that the individual filaments are usually set at a constant nominal distance from each other, so that the “area provided with filamentary damage” ends where the next adjacent filament is set at a distance of more than twice this nominal distance from the respective filament.
Advantageous embodiments of the invention are the subject of the subclaims.
Particularly with regard to the usually selected other parameters of such a glass element, such as the glass thickness or the lateral expansion, the respective beveled edge surface in its area provided with the filamentary damages very preferably has a surface roughness with a mean roughness value of about 1 μm.
In a particularly advantageous further development, other geometric parameters of the glass element are also specifically selected to support the functionalities to be improved. In a departure from the design criteria provided in the known glass element with the design objective of facilitating separation of the elements from one another, the edge surface is now particularly preferably inclined by an angle of inclination of 0.5° to 3° relative to the surface normal of the side surfaces. This means that comparatively small angles of inclination of the edge surface relative to the surface normal of the side surfaces are particularly preferred. In particular, a combination of design criteria is taken into account in the choice of parameters for the angle of inclination in a very particularly preferred design: on the one hand, there is a general endeavor to avoid generally deviating angles, since 90° angles are often also specified on the component side. In this sense, comparatively small angles would be desirable. An increase in the angle, on the other hand, means increasingly easier recognition; a doubling of the machined surface in the top view generally also means twice as good visibility. From this point of view, larger angles of inclination would be preferable—preferably in compliance with the boundary conditions specified on the component side.
As has also surprisingly turned out, the effects and functionalities achievable through the targeted adjustment of the surface roughness are particularly well usable for glass elements of comparatively low thickness. Particularly preferably, the glass element therefore has a thickness of at most 6 mm, preferably at most 3 mm.
With regard to the process, the above-mentioned task is solved in that the filaments forming the perforation are produced in the glass substrate in such a way that the edge surface resulting after breaking and exhibiting the damages caused by the filaments has a surface roughness with a mean roughness value of at least 0.3 μm, and preferably of at most 2 μm, in a particularly advantageous embodiment of about 1 μm.
Particular account is taken of the fact that the optical quality of the edge is decisive for its recognizability. In addition to the material properties such as optical density, interface size in the fracture pattern, brittleness, and the like, it is determined by the processing (polished, ground, broken, etc.). In laser modification cutting, the surface of the edges consists of at least two surface portions, namely the filament itself and the fracture area between the filaments. The edge surface and especially its surface roughness can be influenced by the number, the dimensioning, the position and also the design of the filaments. A large number of filaments with small dimensions and close spacing result in a surface with a comparatively low roughness. Large filaments, on the other hand, increase the surface roughness. The half channel created by the modification in the middle of a break is part of the surface and thus also contributes to the surface roughness. The fracture area between the modifications determines the rest of the surface properties. When setting the surface roughness, the ratio of free fracture area to filament fracture area must therefore also be taken into account. Furthermore, it is also conceivable to-introduce deliberately pronounced (e.g. particularly large or small, . . . ) modifications at fixed intervals in addition to the normal ones in order to achieve the desired surface roughness.
Advantageously, during the production of the perforation or the filaments forming it, the perforation laser is set at an angle to the surface normal of the glass substrate in such a way that the filamentary damages forming in the glass substrate are inclined with their longitudinal direction relative to the surface normal of the glass substrate by an angle of inclination of between 0.5 ° and 3 °. It may have to be taken into account that—given the laws of refraction—the filament axis direction in the glass substrate does not necessarily correspond to the laser propagation direction, i.e. the direction of the laser beams impinging on the substrate.
Notwithstanding the explained achievable improvement of the functional properties of the glass element through the intended adjustment of the surface roughness in the area of the edge surfaces, the inclined design of the edge surfaces also offers the already known advantages in the removal or separation of the glass elements during the separation of the glass substrate. During the separation of the components from adjacent components or surrounding material, the inclined cut has a positive effect, especially in a removal direction parallel to the surface normal, as this provides a removal inclination. The components are generally interlocked by the surface roughness. The removal slope, i.e. the opening, diverging orientation in the removal direction, reduces the risk of damage during removal due to scallops or edge chipping. Automation of the removal process is thus facilitated or even made possible by the removal slope. To further facilitate this, in alternative or additional advantageous further development, which is moreover considered to be independently inventive, additional measures are provided for facilitating the separation or separation of the glass elements from one another. For this purpose, the glass substrate is advantageously locally heated or locally cooled in a region in the vicinity of the perforation after the introduction of the filamentary damages. In this way, thermal or mechanical stresses are specifically generated in the vicinity of the perforation of the glass substrate, which increase the separation gap and thus reduce the “interlocking” during removal.
The advantages achieved with the invention consist in particular in the fact that the glass element can be strengthened and improved for a multitude of subsequent uses and with regard to its functionalities by the targeted adjustment of the surface roughness of the edge surface. In addition to the simplification of the removal or separation of the components, which can in principle be achieved by the beveled edge surfaces, as provided in the present case, but also by comparatively small angles of inclination, it is also possible to achieve simplified further processing, including automated processing, as a result of the improved visual recognizability, and/or improved bondability.
In particular, users of the glass element, e.g. when installing it in complex systems or when processing it into the end product, may view the process-related damage caused by laser filamentation critically for aesthetic or process-related reasons, e.g. because of stray light caused by edge damage such as shells when light is coupled in, e.g. for displays. Such disturbing effects can be kept to a minimum, especially due to the improved removal of components, even when cutting at an angle that deviates only slightly from 90°. Especially for the comparatively small component thicknesses that are particularly preferred, these deviations are not considered to be particularly disturbing or are accepted. The targeted use of the edge surface properties provided for here can thus improve detectability without having to accept the disadvantages mentioned.
An embodiment of the invention is explained in more detail with reference to a drawing. Shown therein is:
Identical parts are marked with the same reference signs in all figures.
The cutting system 1 according to
For the actual cutting of the glass substrate 2, hence for its separation into individual glass elements 12, i.e. for the separation of the parts along the cutting line 8 and the perforation 10, a breaking process is provided subsequent to the filamentation, i.e. after the insertion of the perforation 10. To facilitate or support the disunion or separation of the glass elements 12 from each other, the introduction of thermal or mechanical stresses in the vicinity of the introduced perforation 10 of the glass substrate 2 is provided. For this purpose, in the example embodiment, the glass substrate 2 is locally heated in a region in the vicinity of the perforation 10 after the filaments forming the perforation 10 have been introduced; alternatively, however, local cooling could also be provided. In the example embodiment, a heating device 14 that can be positioned locally relative to the surface of the glass substrate 2 is provided for the purpose of local heating.
The cutting system 1 is designed to facilitate the removal or separation of the glass elements 12 produced during separation. In particular, the knowledge is taken into account that in principle a gap-free separation is produced during perforation or modification laser cutting. If the glass elements 12 are then to be separated from each other or from the surrounding bulk material, this is often not possible without causing damage. Furthermore, separation and removal is made more difficult with increasingly complex cutting patterns such as radii, corners or polygons. Typical removal damages are shells, chipping or cracks at the separation edges. In order to counteract this and to facilitate the removal or separation of the glass elements 12, the perforation laser 4 is adjusted for an inclined impingement of the laser beams on the glass substrate 2 relative to the surface normal of the glass substrate, indicated by the arrow 16, when the filaments forming the perforation 10 are introduced.
This oblique or inclined impingement of the laser beams results in the filamentary damage produced in the glass substrate 2 also being inclined or oblique to the surface normal of the glass substrate 2. This is shown schematically in
During the subsequent breaking or separating of the glass substrate 2, glass elements 12 with sloping or inclined edge surfaces 20 are accordingly produced. As can be seen from the enlarged sectional representation in
In addition to the facilitation of removal and separation achieved by the inclined orientation of the edge surface 20, the glass element 12 is designed for particularly good usability in a variety of possible applications. This is based on the realization that the beveled edge surface 20 can be specifically refined in the sense of providing additional functionalities, in this case in particular optical recognizability and/or bondability. In order to achieve this, the edge surface 20 has a surface roughness with a mean roughness value of approximately 1 μm in its area provided with the filament-shaped damages 24.
The intended surface roughness is set during the filamentation step by suitable parameter selection and process control. In particular, the number, the dimensioning, the position and also the design of the filaments are essential parameters for the resulting surface roughness, and they are suitably selected and adjusted according to the desired surface roughness. Furthermore, it is also conceivable to introduce deliberately pronounced (e.g. particularly large or small, . . . ) modifications at fixed intervals in addition to the normal ones in order to achieve the desired surface roughness.
For the sake of improved comprehensibility, in particular with regard to the angle of inclination of the edge surface 20, the illustration in
List of reference signs
1 cutting system
2 glass element
4 perforation laser
6 control device
8 cutting line
10 perforation
12 glass element
14 heating device
16 arrow
18 laser pulse
20 edge surface
22 side surface
24 damage
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 215 264.3 | Oct 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/077413 | 9/30/2020 | WO |
