Method for forming glass sheets into glass parts and forming tool for use in said method

Abstract

The present invention relates to a method for forming a glass sheet into a glass element 12, which includes a base surface 14 and provides several protrusions 16, the protrusions being intended to form surface structure elements that can be identified by the user by touch. The object of the present invention is to ensure a particularly high mechanical load-bearing capacity of the glass element 12, or in particular the formed element, in a simple and reliable manner, even in the case of relatively complexly constructed structure elements. This object is achieved in accordance with the present invention in that the glass sheet is placed in the forming tool 10 on several forming punches 22 corresponding to the desired protrusions 16, and then heated to soften the material, so that the glass material takes the contours of the bottom 20 of the forming tool 10 to form the base surface 14 between the forming punches 22.

Description

[Technical field]

[0001] The present invention relates to a method for forming a glass sheet into a glass part that includes a base region and has several structures for forming surface structure elements that can be felt by a user.The present invention further relates to a forming tool for use in the method. [Background technology]

[0002] Flat control elements such as touch screens or touch pads are increasingly being used in motor vehicles as a means of inputting user instructions, for example to control navigation or entertainment systems. Such touch controls can for example be designed as simple linear touch controls, so-called "touch sliders", which in principle can be arranged in any shape, for example as straight or curved lines. When used in motor vehicles, touch sliders can for example implement operations in predefined directions. Furthermore, such touch control elements can also be designed as flat control elements, which are used for example to control the input pointer of an optical input device in two axes. Such touch controls intended for use in motor vehicle cockpits are known, for example, from DE 102012020570 A1 and DE 102016122972 A1.

[0003] Known touch control elements are usually designed as flat control elements with flat "straight" surfaces, using touch screens or touch panels known per se. However, in the design of modern motor vehicle cockpits and interiors, there is an increasing desire both for design or styling reasons and for functional reasons, i.e. in the sense of providing a contour that can be tactilely grasped by the user, to design such display and / or control elements as elements with small or large contours, which can for example be harmoniously integrated into the design and functional concept of the vehicle's interior design, or which, from a design point of view, present a spatial shape familiar to the user, for example a rotary control, making them recognizable. For the same reasons, it is also particularly desirable to use glass as a surface material for such display and / or control elements, since in this way a particularly high-quality overall impression of the vehicle's interior design can be provided to the user.

[0004] However, when using glass as a surface material for such contouring and / or control elements, it must be taken into account that glass is subject to certain boundary conditions with respect to shaping or contouring by the material. In particular, glass can be formed into almost any shape by specific pressing or casting processes. However, soda-lime glass must be heated to temperatures well above 800°C, and the pressing tool determines the surface quality of the component. However, such pressing processes are not an option for larger components. Furthermore, a high degree of mechanical stability and resilience is particularly important when used as a control element exposed to repeated or frequent accesses. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent No. 102012020570 [Patent Document 2] DE 102016122972 Summary of the Invention [Problem to be solved by the invention]

[0006] The invention is therefore based on the problem of identifying a method for producing glass parts that are particularly suitable as display and / or operating elements in the interior of a motor vehicle by forming glazing elements which allows a particularly high mechanical load-bearing capacity of the glass parts or formed parts to be achieved in a particularly simple and reliable manner even for relatively complexly constructed structural elements. Furthermore, there is a need to identify forming tools which are particularly suitable for use in such a process. [Means for solving the problem]

[0007] In terms of processing, this problem is solved according to the invention by heating the glass sheet in a forming tool to soften the material and, before or during the shaping that occurs, placing the material in several forming plungers that correspond to the intended structure, so that the glass material takes the contour of the base of the forming tool between the forming plungers and forms the base area.

[0008] The process according to the invention is therefore particularly distinguished from the processes previously customary in such situations, in particular from deep drawing processes, in which a forming tool with recesses or indentations corresponding to the intended structural elements is used on the support base. In such known processes, the glass sheet is placed in the bottom area of ​​such a forming tool for shaping. After heating to soften the material, the glass then flows into the recesses or indentations and, after cooling and hardening, forms the desired structure or spatial shape on the surface.

[0009] However, surprisingly, the structures thus produced turned out to have a relatively unexpectedly low wall thickness, especially in the region of the side walls, so that it must be assumed that there is an increased risk of breakage. This is particularly important when the structural elements formed on the base surface are not only provided with a decorative or aesthetic function, but are also used functionally, i.e. as operating elements. This is the case, for example, when such structural elements are designed in a manner of rotational control. The increased physical contact with the structural elements associated with such an intended use, for example as a result of touch in the case of touch elements, actually requires an increased breakage resistance to ensure the desired lifespan of the glass part.

[0010] To take this into account, the present process is specially designed to generate a relatively high wall thickness even in the wall region of the formed structural element during the forming of the glass, which results in the desired high mechanical stability. Surprisingly, such an increase in wall thickness can be achieved by providing a forming tool in the manner of an "inverted forming process" with a profile plunger, instead of a depression or recess arranged at the position of the intended structural element, where the glass sheet can be placed before forming or where it will be placed when the material starts to soften and is formed. During further forming, the softened glass can sink between the profile stamps and take the contour of the bottom of the forming tool.

[0011] Very surprisingly, the desired generation of sufficiently thick walls in the region of the side walls of the structural elements thus becomes particularly advantageous. Advantageously, during the shaping of the glass material, a lateral flow of material is generated towards the side flanks of the shaping plunger. A concentration of material in these regions can thus be achieved, which directly favors the desired reinforcement of the side walls. Such a cross-flow of material can be adjusted and promoted, in particular by setting a suitable temperature profile in the shaping tool. This makes use of the knowledge that the softened and flowing glass material is locally cooled or at least heated to a lesser extent during the (first) contact with the shaping punch compared to the rest of the glass, so that the flowability of material in the plane or front regions of the structures or the structural elements shaped by them is reduced compared to the rest of the glass material. This results in a relatively increased flow effect from relatively warmer or hotter regions of the base surface, generating the desired lateral flow of material. In a particularly advantageous further development, the shaping tool is heated less in the region of the shaping plunger during the shaping of the glass material than in the base region between them.

[0012] In an alternative or additional advantageous further development, this effect can be used to particular advantage by selectively and optionally cooling the forming tools in the region of the side walls or side flanks of the structure, in this way the flowability of the material can be particularly reduced in these regions, so that the outflow of the material can be kept particularly low.

[0013] With regard to a forming tool for use in the aforementioned type of process, the aforementioned problems are solved with a tool base on which a number of raised forming plungers are shaped. The forming tool is therefore designed in an "inverted version" manner, such that when the glass element is to be formed, it is first placed on the upper surface of the forming plungers and then, after the material has softened, is stretched over the entire surface "in the mold" towards the tool base between the forming plungers.

[0014] In order to ensure in such an arrangement in a particularly reliable manner a particularly high wall thickness in the region of the sides of the structural element, the forming tool is advantageously designed to create a lateral flow of the glass to be processed towards the forming plunger, so that the material collects in that region and thus results in a higher material thickness. For this purpose, the tool base of the forming tool is advantageously heatable, preferably independently heatable in segments.

[0015] In order to further promote this cross-flow of material, in an additional or alternative advantageous further development, the tool bottom of the molding base is at least partially designed with low friction, for example with a particularly smooth or polished surface and / or comprises a friction-reducing coating, preferably of graphite or boron nitride.

[0016] The advantages achieved with the invention lie in the fact that, in particular, due to the design of the forming tool as a "reversal tool" and the design of the forming process in such a way that the glass sheet comes into contact first with the forming plungers during forming, so that the glass material for forming the base area between the forming plungers takes the contour of the base of the forming tool, particularly high wall thicknesses at the side walls of the structural elements can be achieved in a particularly simple and reliable manner, so that the shaped glass parts have a particularly high mechanical load-bearing capacity and breaking strength, even for relatively complex surface structural elements and for structural elements directly intended as operating elements, such as rotary actuators.

[0017] An embodiment of the present invention will now be explained in more detail with reference to the drawings. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a forming tool of known design. [Diagram 2] FIG. 1 is a perspective view of a forming tool according to the present invention. [Diagram 3] 1 is a cut-out of a cross-section of a molded glass part. [Figure 4] 3 is a cross-sectional cutaway of a glass element positioned in a forming tool as shown in FIG. 2 prior to forming. [Diagram 5] 3 is a cutaway cross-sectional view of the glass element after forming and placed in the forming tool as shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Identical parts are given the same reference symbols in all figures.

[0020] The well-known forming tool 1 shown in FIG. 1 and the forming tool 10 according to the invention shown in FIG. 2 with a formed glass part 12 are respectively used to form or shape a glass sheet provided as a starting or intermediate product into a formed glass part 12 adapted to a specific application. The starting product is in this case called a "glass sheet" since it is a glass element with a laterally extended surface. It can be "flat" in the horizontal sense, but it can also be curved or pre-curved. In the example of the embodiment, the formed glass part 12 produced from the glass sheet by suitable forming is intended for use as a touch control element in the cockpit of a modern automobile and for this purpose is designed as a contoured glass component 12 with a base area 14 in which several structures 16 are formed, intended to form surface structure elements that can be felt by the user, in particular to provide a contour that the user can detect tactilely. In the example of the embodiment, the structures 16 are intended for the user to perceive the appearance and function of a rotary control or dial, and therefore a particularly preferred embodiment of a glass part 12 is shown in which the structures 16 are in the form of a cylindrical disk with a substantially round cross section in this case. Of course, the shaped and contoured glass component 12 may also be designed and conceived for other purposes and may include other surface structure elements adapted thereto.

[0021] The forming tool 1, 10 shown in Fig. 1, Fig. 2 is provided for producing a glass part 12 by forming a glass sheet element. The forming tool 1 according to Fig. 1, known per se, is designed in this context to carry out a customary deep drawing process. For this purpose, the forming tool 1 is provided with several indentations or recesses 4 in its support base 2 which correspond to the structural elements provided. For forming, the glass sheet is placed on the support base 2 of the forming tool 1. The glass is subsequently heated to a temperature above the material softening point, so that the glass material starts to flow. The glass thus flows into the recesses 4 or indentations and, after cooling and hardening, forms the desired structure or spatial shape on the surface.

[0022] In comparison, the forming tool 10 according to the invention shown in FIG. 2 is in the form of an “inverted” forming tool. The forming tool 10 comprises a tool base 20 in which several raised forming plungers 22 are shaped. The number, position and shape of the forming plungers 22 are appropriately selected to match the structure 16 to be provided on the glass part 12. Furthermore, a number of suction or vacuum channels 24 are integrated and arranged in the tool base 20, in particular between the forming plungers 22, which are connected to a suction or vacuum system not shown in more detail. In this embodiment of the forming tool 10, which is considered inventive in itself, the forming of the glass sheet into the glass part 12 is carried out by first placing the glass sheet on the platform-like upper side 26 of the forming plungers 22 and / or on the circumferential support rim and then heating it to soften the material. In particular, it is ensured that the glass sheet, in connection with the forming, comes to rest first on the platform-like upper side 26 of the forming plungers 22, so that it cools more or less in these areas compared to the rest of the glass material, and its fluidity is accordingly reduced. During further forming, the glass material for forming the base region 14 between the forming plungers 22 adopts the contours of the tool base 20 of the forming tool 10. To assist this, if necessary, a suction vacuum is set up between the tool base 20 and the glass gob via the vacuum channels 24, which further encourages the glass gob to adhere to the surface of the tool base 20.

[0023] The glass component 12 produced during the forming process is partially shown in cross section in Figure 3. The base region 14 is connected via a respective side wall 28 to the respective front panel 30 in the area of ​​the respective moulding 16. Completely surprisingly, the concept of "reverse moulding" according to the invention by the moulding tool 10 makes it possible to achieve by relatively simple means and nevertheless particularly reliably that the resulting side walls 28 of the structure 16 have a relatively large wall thickness d and thus a relatively high mechanical load-bearing capacity and breaking strength.

[0024] This desired increase in the load-bearing capacity and breaking strength of the glass component 12 is also further enhanced in regions of the structure 16 by establishing a relatively large wall thickness d of the sidewalls 28, in that, in an embodiment considered independently inventive, during forming of the glass material, a lateral flow of material is generated towards the side flanks 32 of the forming plunger 22. In this way, the glass material is selectively concentrated in these regions, which directly results in an increase in the thickness or wall thickness d of the sidewalls 28 generated in these regions.

[0025] To create or promote this material cross-flow, the forming tool 10 can be heated locally and independently in segments of the area of ​​its tool base 20. For this purpose, individually controllable heating or cooling elements 34 are arranged on the tool base 20. By means of these, a suitable temperature profile, in particular a suitable temperature gradient, can be set in the tool base 20 and in the forming plunger 22 during forming, which, by a suitable change in the viscosity or flow properties of the glass material to be processed, favors a material accumulation in the area of ​​the forming plunger 22 and thus a precisely desired material cross-flow. On the other hand, the tool base 20 is also provided with a friction-reducing coating 36, which also further improves the lateral flow properties of the glass material.

[0026] Figure 4 shows a partial cross-section of a glass sheet positioned on the platform-like upper side 26 of forming plunger 22 before being formed, while Figure 5 shows, also in partial cross-section, the glass sheet being formed into glass component 12. The lateral flow of material towards forming plunger 22 is represented by arrows Q. [Explanation of symbols]

[0027] 1 Forming tool 2 Support Base 4 Recess 10 Forming tools 12 Glass parts 14 Base Area 16 Structure 20 Tool Base 22 Molded plunger 24 Vacuum Channels 26 Upper side 28 Side wall 30 Front Panel 32 Side flank 34 Heating or cooling elements 36 Coating d wall thickness Q Arrow

Claims

1. A method for forming a glass sheet into a glass part (12) comprising a base area (14) and a plurality of structures (16) intended to form surface structure elements having a contour that can be tactilely detected by a user, comprising the steps of: a forming tool (10) is provided having a base (20) and a number of forming plungers (22) corresponding to said base region (14) and said number of structures (16), said base (20) being provided with a number of vacuum channels (24); the glass sheet is heated in the forming tool (10) to soften the material, and prior to or during the resulting forming, the glass sheet is placed on the forming plungers (22) and the glass material is drawn through the vacuum channels (24) to assume the contour shape of the base (20) to form the base region (14) between the forming plungers (22); During forming of the glass material, a lateral flow of material towards a side flank (32) of the forming plunger (22) is generated; A method wherein, during shaping of the glass material, the forming tool (10) is heated less in the region of the forming plungers (22) than in the bottom region therebetween.

2. 2. The method of claim 1, wherein the lateral flow of material is promoted by use of the forming tool (10) and the base (20) at least partially comprises a friction reducing coating (36), preferably graphite or boron nitride.

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