Method for forming high-hardness carrier sheets

Abstract

A method for forming a high hardness carrier sheet, particularly a glass sheet, includes the steps of providing a high hardness solid carrier sheet having a thickness of at least 6 mm, covering a front surface of the carrier sheet with a removable vibration-absorbing protective layer (S100), providing a glass sheet on a surface of the protective layer remote from the carrier sheet (S110), and forming a plurality of cavities according to a predetermined pattern on a back surface of the carrier sheet opposite the front surface of the carrier sheet. The step of forming the cavities includes the steps of forming cavities by milling (S120) such that in each cavity the remaining thickness of the carrier sheet along the front surface is at least 3 mm and at most 5 mm; during milling, at least one physical characteristic of the vibration of the carrier sheet is continuously measured on the front surface of the carrier sheet by at least one sensor (S121); based on the at least one physical characteristic measured by the sensor, adjusting the operation of the milling tool such that the vibration characteristic of the carrier sheet does not exceed a predefined threshold; taking a first 3D image of the surface roughness of the milled cavities by applying a first optical method (S130); and measuring the thickness of the cavities by shot blasting (S131). The method includes a step of further reducing the surface roughness of the cavity (S140), where the operation of a shot blasting tool during shot blasting is controlled using parameters determined based on the first 3D image taken during the first scan, a step of taking a second 3D image of the surface roughness of the shot blasted cavity by applying a second 3D scan (S150), and a step of further reducing the surface roughness of the cavity by applying laser beam milling (S160), where the operation of a laser beam milling tool is controlled based on the second 3D image taken after laser beam milling by the second 3D scan, such that the surface roughness of the cavity is in the sub-micron range.

Description

[Technical field]

[0001] The present invention relates to a method for processing a carrier sheet having high hardness, and more particularly to a method for forming cavities of a predetermined pattern on one side of a carrier sheet having high hardness for mounting electronic units therein. [Background technology]

[0002] The construction industry favors cladding and decorative elements made of natural and artificial materials such as stone, machined wood, natural wood, composites, plastics, or combinations thereof. Various opaque tiles are thinned to a degree that they can function as display surfaces in certain areas, making them suitable for displaying pictograms and animations, for example. Making high-strength carrier sheets thin enough for a relatively small size range, such as a few centimeters in diameter, is a major technical challenge with currently known machining techniques.

[0003] US Patent No. 5,399,633 discloses a robotic cell for cutting, milling, grinding and polishing large sheets of natural materials. The multi-axis robot can also be equipped with a water jet head for processing the boards individually.

[0004] Patent document 2 describes the machining of a product made of natural stone. The stone product has at least one light-transmitting surface and at least one light source that illuminates the light-transmitting surface. When the light source integrated in the stone product is not activated, only the natural pattern of the rock is visible on the surface of the stone product. The wall thickness of the translucent surface is 0.5 mm to 3.5 mm by sawing, sanding, and polishing.

[0005] The disadvantage of the above solution is that when the high hardness carrier sheet is thinned, the roughness of the machined inner surface is relatively large, so that the light transmitted through the surface is significantly attenuated, and it is necessary to install a relatively high and therefore large electronic light-emitting unit. In large electronic devices, it is necessary to cut a wide cavity, which on the one hand weakens the mechanical strength of the entire carrier sheet, and on the other hand greatly reduces the resolution of the image that can be displayed.

[0006] Additionally, traditional machining processes can cause breakage and micro-cracks in the carrier sheet material, leading to quality issues or lost production. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Nishikoku Utility Model No. 1129455 Specification [Patent Document 2] Chinese Patent No. 109968543 Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to improve upon conventional methods of processing high hardness carrier sheets, allowing such carrier sheets to display higher resolution images without significantly reducing the maximum available light intensity. [Means for solving the problem]

[0009] This object is achieved by a method according to claim 1. Preferred embodiments of the method according to the invention are defined in the dependent claims.

[0010] In the following, the process according to the invention will be explained in more detail with reference to the drawings. [Brief description of the drawings]

[0011] [Figure 1]FIG. 2 is a flow diagram showing the main steps of the molding method according to the present invention. [Figure 2a] FIG. 2 is a schematic cross-sectional view of a molded carrier sheet before molding. [Figure 2b] FIG. 2 is a schematic cross-sectional view of a molded carrier sheet after molding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] As used herein, a "high hardness carrier sheet" refers to a sheet of hard natural or man-made material that is opaque at commercially available thicknesses, but can be illuminated with a relatively low power light source when thinned sufficiently. Such materials include gres, stoneware, natural marble, engineered marble, concrete, and the like. Depending on the intended use, the carrier sheet can be a wall tile, floor tile, home furniture tile, office furniture tile, multi-function table top, free-standing display panel, worktop, and the like.

[0013] The main steps of the method according to the invention will now be described with reference to the flow diagram shown in Figure 1. The moulding process is carried out on a carrier sheet 1 which is shown in cross section in Figure 2a.

[0014] The carrier sheet 1 is initially a solid sheet and has a front surface 10, which is the surface of the carrier sheet 1 that is normally visible to the user. Opposite the front surface 10, the carrier sheet 1 has a back surface 11, on which an electronic unit required for illuminating the carrier sheet 1 is attached. In order to be able to illuminate the carrier sheet 1, the carrier sheet 1 is thinned from the direction of the back surface 11. The back surface 11 of the carrier sheet 1 is normally not visible to the user during use after the carrier sheet 1 has been installed.

[0015] The typical size of the carrier sheet 1 formed by this method is at least 100 mm x 100 mm, usually 1200 mm x 1200 mm, but not more than 6000 mm x 2000 mm. The thickness of the carrier sheet 1 before forming is typically at least 6 mm.

[0016] Before starting the molding process, the carrier sheet 1 is preferably cleaned, for example with alcohol or other cleaning agents, to thoroughly remove organic and inorganic contaminants, such as fats or auxiliary agents, from its front surface 10 and back surface 11 that may have come into contact with the carrier sheet 1.

[0017] In the first step S100 of the method according to the invention, the front surface 10 of the carrier sheet 1 is covered with a protective layer 20. The protective layer 20 is preferably a high-tensile plastic film. By using the protective layer 20, micro-vibrations of the carrier sheet 1 caused by mechanical processing means during the molding step can be significantly reduced. Since the aim of high-precision surface treatment is to achieve a surface roughness smaller than the amplitude of such micro-vibrations, the elimination of micro-vibrations is essential. In the present invention, the protective layer 20 can be, for example, a protective film "Protect" from the company 3M, having a thickness of 50-500 μm. The protective layer 20, in particular a plastic protective film, is electrostatically fixed to the front surface 10 of the carrier sheet 1, so that the protective layer 20 can be removed from the carrier sheet 1 at the end of the molding process or at a later time. The protective layer 20 remains on the carrier sheet 1 throughout the process, thus protecting the front surface 10 also from mechanical impacts such as chips, dirt, scratches and low-power shocks.

[0018] In a further step S110 of the method, a glass sheet 30 with a thickness of at least 4 mm is placed on the surface of the protective layer 20 opposite the carrier sheet 1 and is glued to the carrier sheet 1 (or more precisely to said protective layer 20). The glass sheet 30 is mechanically matched to the material of the carrier sheet 1, which further increases the rigidity of the carrier sheet 1, further reduces micro-vibrations due to the machining process and properly distributes mechanical stresses that arise locally in the carrier sheet 1 due to mechanical loads. Its use therefore prevents the formation of undesired hair cracks in the carrier sheet 1 during the machining process.

[0019] Since the glass sheet 30 and the protective layer 20 together form a transparent layer on the front surface of the carrier sheet 1, defects in the material structure of the front surface 10 of the carrier sheet 1 can be detected already during the forming process.

[0020] On the other hand, the glass sheet 30 provides the carrier sheet 1 with mechanical static rigidity until the final stages of machining, and since the glass sheet 30 forms an integral part of the carrier sheet 1, it also protects the front surface 10 of the carrier sheet 1 from external influences. The carrier sheet 1 with the protective layer 20 and the glass sheet 30 can be placed in a fixed frame for movement and machining, which holds the sandwiched layers together during machining and subsequent installation.

[0021] After applying the protective layer 20 and the glass sheet 30, cavities 50 are formed on the back surface 11 of the carrier sheet 1, into which the light-emitting electronic units can be inserted. The shaping starts with milling in step S120. The milling is preferably carried out using a CNC machine, such as a milling center "Profile 6033 CNC" manufactured by CMS. A machining plan is prepared based on a predefined pattern of the cavities 50 to be formed, and then the toolpath is generated using the software of the CNC machine. The cavities 50 to be formed are typically formed with a floor area of ​​100 mm x 100 mm to 1900 mm x 1100 mm, depending on the function of the electronic units to be installed. The CNC milling in step S120 creates the cavities 50 in the carrier sheet 1, typically with an accuracy of tenths of a millimeter, but optionally with an accuracy of one hundredth or one thousandth of a millimeter. For example, in the case of a carrier sheet 1 having a thickness of 6 mm, each cavity 50 is formed by removing a thickness of approximately 2.1 mm, i.e. the thickness of the thinned portion of the carrier sheet 1 is approximately 3.9 mm, which in the case of, for example, a gloss sheet, is a sufficiently reduced thickness to allow transillumination by a laser light source (e.g. a laser matrix or laser projector) having an output of, for example, 0.1 to 30 W.

[0022] Factors that significantly influence the selection of the technological parameters of the milling operation in step S120 include: · The composition of the material of a given carrier sheet 1 (as gres, stoneware or marble are not perfectly consistent materials). Humidity and temperature in the vicinity of the carrier sheet 1 (as too many changes in the material parameters during the milling of the carrier sheet 1 may lead to damage). · The thickness of the carrier sheet 1 (as the material loses strength during thinning and therefore cracks may appear on the front 10 or back 11 of the carrier sheet 1). the location of the cavities 50 to be machined on the carrier sheet 1 (i.e. if, for example, the cavities 50 are located at the edge of the carrier sheet 1, the cutting speed has to be increased, for example by increasing the tool speed, which will amplify micro-vibrations in the material). the thickness of the thinned parts of the carrier sheet 1 (since the cutting speed must also be increased when machining the bottom of the cavity 50, and thus the micro-vibrations formed in the material are also amplified in the thinned parts).

[0023] In order to reduce or eliminate the above-mentioned adverse effects, the carrier sheet 1 with the protective layer 20 and the glass sheet 30 is preferably placed on a vacuum worktable and the entire area of ​​the carrier sheet 1 is fixed to the worktable with a substantially uniform force distribution. However, to avoid the increase of internal stresses in the material due to the machining process, the vacuum fixing allows the carrier sheet 1 to resonate slightly.

[0024] To avoid high resonance, in step S120, a real-time resonance test is performed on the carrier sheet 1 during milling, so that machining parameters such as, for example, CNC machine speed, milling head feed, coolant flow rate are continuously controlled to ensure that the vibration characteristics of the carrier sheet 1 do not exceed predetermined thresholds.

[0025] During the resonance test, various physical properties can be measured, such as, for example, the vibration amplitude, the vibration frequency, the lateral propagation of the vibrations of the carrier sheet 1. The resonance test can be performed in several ways: Physical vibration measurement (preferably by sensors) at the four corners of the carrier sheet 1. Optical vibration measurement (preferably with a laser measurement system) at least four points within a range of 80mm-200mm from the surface of the machined object. Vibration measurement over the entire surface of the carrier sheet 1 (preferably by a camera system).

[0026] During milling in step S120, acoustic effects can also be examined to infer material defects. For example, if an imbalance occurs during drilling at the beginning of milling, the acoustic effects of the machining will change, which may indicate that some technological parameters are not correct even before cracks form. Changed acoustic effects compared to pre-stored acoustic samples may indicate problems such as wear of the drill bit, movement of the support, changes in rotation speed, changes in the amount of coolant, etc.

[0027] When milling high-hardness materials such as grace, it is preferable to use a diamond-coated milling head with a diameter of 1.5 mm to 4 mm. During milling, the rotation speed of the CNC machine is preferably adjusted in the range of 7,500 to 12,000 rpm.

[0028] The thinned areas in the cavities 50 may appear wavy to the naked eye due to small vibrations of the carrier sheet 1 during milling, so that the thickness of the carrier sheet 1 after milling is non-uniform and the processing tool leaves grooves and marks on the surface of the cavities 50. These surface irregularities are optically imaged with a first image resolution in step S130 of the method. The image is preferably obtained by optical scanning, a so-called scan, and the scan is carried out with an image resolution of 10 to 500 μm. The purpose of the 3D scan of the surface is to allow the surface of the cavities 50, especially the inner surface of the thinned parts, to be further transparent in the following molding step or to realize sensory detection or fluid excitation in other applications.

[0029] After the first scanning step, in step S140 of the method, the irregularities created by milling on the inner surface of cavity 50 are further reduced by shot blasting. As a result of the surface scan in step S130, a 3D image of the grooves and valleys created on the surface of cavity 50 is obtained. Based on this 3D image, the edges of the valleys created by the milling head of the CNC machine are blown off, but only to the extent that a sufficiently smooth surface is obtained for an additional surface smoothing step.

[0030] In the method of the invention, in step S140, it is preferable to sandblast the inner surface of the cavity 50. For this purpose, it is preferable to use a sandblasting system that can achieve a surface roughness of about 10 μm. The sandblasting system is preferably operated with operating parameters determined based on the analysis of the 3D images acquired during the scanning in step S130. Preferably, the flow rate of the particles can be controlled. During sandblasting, several types of sand can be used, the particle size of the sand used can be between 11 μm and 800 μm. The sandblasting head is continuously moved by the robot arm, so that the sandblasting head never returns to the same surface point but always follows a different path on the carrier sheet 1. It is also possible to process convex surfaces using a sandblasting head equipped with a tilting mechanism of the robot arm. The sandblasting system can be, for example, the sandblasting system "Mistral Zephir" from the company Fratelli Pezza, but other systems can also be used for other production parameters.

[0031] During the forming in step S140, not only sandblasting but also other types of blasting media such as steel or corundum particles may be used.

[0032] After shot blasting, in step S150 of the method, another step of 3D scanning is performed with a higher image resolution than that used in the first scanning step. During the scanning in step S150, a 3D image of the inner surface of the cavity 50 is taken, preferably with a resolution of 1-10 μm.

[0033] Following shot blasting, in step S160 of the method, an excimer laser beam type milling head is used to apply a very precise finish to the inner surface of the cavity 50, creating a substantially polished surface. By applying the laser beam milling, no further significant amounts of material are removed, only the surface of the cavity 50 is made perfectly uniform, so that the thickness of the carrier sheet 1 in the thinned areas is perfectly the same (at least the thickness variation is within sub-micron tolerances).

[0034] During laser beam processing, the resonance of the carrier sheet 1 is preferably continuously measured by an integrated sensor and the operating parameters of the laser beam milling machine are controlled based on the measurement data.

[0035] During the laser milling in step S150, a standard industrial excimer laser beam milling machine is preferably used, where a laser beam emitting head is moved to the surface area to be processed by a driver unit on the processing station. The surface resulting from the laser milling is already smooth enough for the light of the light source arranged in the cavity 50 to pass through the material of the carrier sheet 1 with minimal losses (reflection, scattering).

[0036] A carrier sheet 1 produced by the method according to the invention is shown in cross section in FIG. 2b.

[0037] The advantage of the method according to the invention is that as a result of multi-step moulding, extremely thin surface areas can be economically formed on one side of a high hardness carrier sheet according to a predetermined pattern, so that the inner surface of the cavity behind the thinned area is very fine-grained and can be machined to an extremely uniform thickness.

[0038] Although the method of shaping the carrier sheet is described herein with reference to mounting an electroluminescent unit therein, it will be apparent to one skilled in the art that the cavities in the grooves can also be used to mount other functional electronic units, such as fluid exciters for sound generation or other electronic units performing sensor detection or heating / cooling, can also be mounted in the carrier sheet behind the thinned surface area.

Claims

1. A method for forming a carrier sheet (1), in particular a gress sheet, of high hardness, comprising the steps of: Providing a solid carrier sheet (1) of high hardness having a thickness of at least 6 mm; A step (S100) of covering the front surface (10) of the carrier sheet (1) with a removable vibration-absorbing protective layer (20); Providing a glass sheet (30) on a surface of the vibration-absorbing protective layer (20) remote from the carrier sheet (1) (S110); forming a plurality of cavities (50) according to a predetermined pattern on a back surface (11) of the carrier sheet (1) opposite to the front surface (10) of the carrier sheet (1); Including, The step of forming the plurality of cavities (50) comprises: a milling step (S120) of forming the cavities (50) by milling such that in each cavity (50) the remaining thickness of the carrier sheet (1) along the front surface (10) is at least 3 mm and at most 5 mm; a measuring step (S121) of continuously measuring at least one physical characteristic of the vibration of the carrier sheet (1) on the front surface (10) of the carrier sheet (1) by at least one sensor during milling; - adjusting the operation of a milling tool based on the at least one physical property measured by the sensor, such that a vibration characteristic of the carrier sheet (1) does not exceed a predefined threshold value; A first 3D image capture step (S130) of capturing a first 3D image of the surface roughness of the milled cavity (50) by applying a first optical method; a step (S140) of further reducing the surface roughness of the cavity (50) by shot blasting, during which an operation of a shot blasting tool is controlled using parameters determined based on the first 3D image taken during a first scan; A second 3D image capture step (S150) of capturing a second 3D image of the surface roughness of the shot blasted cavity (50) by applying a second 3D scan; a step (S160) of further reducing the surface roughness of the cavity (50) by applying laser beam milling, the step controlling the operation of a laser beam milling tool based on the second 3D image taken after the laser beam milling by the second 3D scan, so that the surface roughness of the cavity (50) is in the sub-micron range; A method comprising:

2. The method according to claim 1, wherein the mechanical protection layer (20) is a protection film with a thickness of 50 to 500 μm, which is electrostatically fixed to the front side (10) of the carrier sheet (1).

3. 2. The method of claim 1, wherein during the first 3D scan (S130), an image resolution of the scan is between 10 and 50 μm, and during the second 3D scan, an image resolution is between 1 μm and 10 μm.

4. The method of claim 1 , wherein the shot blasting step (S140) comprises sand blasting.

5. The method according to claim 1, wherein in the milling step (S130), the rotation speed is controlled in the range of 7500 to 12000 rpm.

6. 2. The method according to claim 1, wherein the material of the carrier sheet (1) is selected from the group consisting of glass, wood veneer, composite wood, acrylic, metal, gres, stoneware, natural marble, artificial marble, granite, and concrete.

7. 2. The method according to claim 1, wherein the carrier sheet (1) has a width of at least 100 mm and a length of at least 100 mm.

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