Worktop, particularly for kitchen furniture, cooking tables or the like, and method for producing a worktop

Description

[0001] The invention relates to a worktop for kitchen furniture, cooking tables or the like.

[0002] The invention further relates to a method for producing a worktop.

[0003] The invention further relates to a kitchen equipment arrangement.

[0004] Although the present invention is generally applicable to any worktop, the present invention will be described with reference to worktops for cooking tables or kitchen furniture.

[0005] In previously known kitchen designs, the hob and work surface, for example, in the form of a stone slab or similar, are manufactured separately and only assembled on-site at the customer's premises. Based on this, it has become known to integrate a hob into kitchen worktops in order to eliminate the visual and essentially physical separation between the cooking surface and the adjacent work area and instead provide a shared surface as a work and cooking area—the worktop.

[0006] DE 20 2016 008 264 U1 discloses a piece of furniture and / or kitchen equipment with a worktop. The worktop is formed from at least one substrate made of monolithic glass material with a surface area greater than 0.7 m², wherein the substrate has a luminosity L* greater than 10, a light transmittance TL less than 50%, an opacity factor greater than 90, and optionally a haze greater than 15%.

[0007] WO 99 / 063334 A1 discloses a glass plate for covering heat-generating elements for use in kitchen furniture, WO 2017 / 042474 A1 discloses glass-ceramic plates for kitchen furniture with high brightness values, DE 10 2018 110 908 A1 discloses a transparent, colored lithium aluminum silicate glass-ceramic, and WO 2012 / 019833 A1 discloses a lithium-containing transparent glass-ceramic.

[0008] In addition to the basic physical and chemical material properties, aesthetic requirements for the worktop must also be taken into account.

[0009] When choosing a light color for the worktop, for example, especially when the worktop is larger than the dimensions of a single hob, visually discernible color differences are undesirable unless, for functional or decorative reasons, a distinctive marking in certain areas is desired. Furthermore, color differences make it difficult to label functions or, in general, to visually identify different areas of the worktop: If a light color for the worktop is also provided with light-colored labels for operating elements, these are less visible and may lead to incorrect operation by the user.If the labels for dedicated cooking surfaces are also light-colored and the countertop is light-colored, cookware may be placed incorrectly due to the labeling being invisible or only partially visible, which can lead to significantly different heat levels in different areas of the cookware. This limits the choice of colors for the labeling of the countertop. A further disadvantage is that the differences in color also result in different transmission in the visible and infrared ranges, which leads to uneven transmission of heat radiation from heating elements located beneath the shared surface.

[0010] An object of the present invention is therefore to provide a worktop and a kitchen equipment arrangement that are simple and cost-effective to produce, have high homogeneity in transmission in the visible and / or infrared range as well as in coloring, and have high flexibility in the color selection for the worktop coloring and the color of the lettering thereof. A further object of the present invention is to provide a method for producing a worktop that is simple and cost-effective to carry out. A further object of the present invention is to provide an alternative worktop, an alternative method for producing a worktop, and an alternative kitchen equipment arrangement.

[0011] The invention solves the above-mentioned problems in one embodiment with a kitchen equipment arrangement according to claim 1

[0012] The invention also achieves the above-mentioned objects in one embodiment by a method for producing a worktop for a kitchen furnishing arrangement according to one of claims 1-11 according to claim 12.

[0013] The term "area" means any zero-, one-, two-, or three-dimensional surface, region, section, volume, line, point, or the like.

[0014] The phrase "based on green glass" in relation to the term "substrate" is to be understood, particularly in the description and preferably in the claims, as a substrate comprising green glass, wherein the green glass of the substrate is either not yet ceramized or the green glass of the substrate is already in partially ceramized form. In other words, the substrate is not yet fully ceramized into a desired end product, such as a keatite solid solution glass-ceramic.

[0015] The term "length in the conveying direction" refers in particular to the extent, dimension, etc. of the substrate which runs or is oriented parallel to the intended direction of passage, transport direction, feed direction, etc. of the continuous furnace.

[0016] The term "L*-a*-b* color space" refers in particular to the color space according to EN ISO 11664-4:2011 (German version of: "Colorimetry - Part 4: CIE 1976 L; a; b; color space (ISO 11664-4:2008)").

[0017] The term "group" with reference to the term "chamber" shall mean one or more chambers.

[0018] One of the advantages achieved is that a worktop can be provided in a simple and cost-effective manner that exhibits high homogeneity in transmission in the visible and / or infrared range. Furthermore, it is particularly visually appealing, as color differences in different areas of the worktop are no longer perceptible. A further advantage is that it makes labels for functional elements or the like particularly easy to see, even if they have a similar basic color to the worktop. At the same time, the selection of possible colors for the labeling is less restricted based on the basic color of the worktop.

[0019] Further features, advantages and further embodiments of the invention are described below or will become apparent thereby.

[0020] According to an advantageous development, the color impression difference ΔE is less than 0.25, in particular less than 0.2, preferably less than 0.13. The advantage of this is, among other things, that the worktop is particularly homogeneous, in particular, a particularly homogeneous color impression is achieved, thus enabling uniform transmission.

[0021] According to a further advantageous development, the respective brightness value L* of the first and second areas is each more than 65, preferably more than 80, in particular more than 90. This makes it possible in particular to provide a worktop with a particularly bright color impression.

[0022] According to a further advantageous development, the magnitudes of the respective green-red parameters and / or the respective blue-yellow parameters of the first and second areas are less than 20. This makes it possible to provide a worktop with a particularly high white color impression. The green-red parameter refers to the value a* in the L*-a*-b* color system, the blue-yellow parameter to the value b* in the L*-a*-b* color system, and the term "magnitude" is to be understood here in the mathematical sense.

[0023] According to a further advantageous development, the surface area of ​​the worktop is more than 1.5 m 2 , preferably more than 2.5 m 2 . This provides a particularly homogeneous worktop even with particularly large dimensions, and in particular, a particularly homogeneous color impression is achieved for the worktop.

[0024] According to a further advantageous development, the hardness of the surface of the worktop, measured as Knoop hardness 0.1 / 20, is more than 600, preferably more than 650, in particular more than 700. This provides effective protection against scratches in the surface of the worktop. The term "Knoop hardness" refers to the indentation hardness according to Knoop in accordance with EN ISO 4545-1:2018 (German version of: "Metallic materials - Knoop hardness test - Part 1: Test methods (ISO 4545-1:2017)").

[0025] According to a further advantageous development, the average flexural strength of the worktop is more than 80 MPa, in particular more than 100 MPa, preferably more than 130 MPa, especially more than 165 MPa. This improves handling, especially with large worktops. The term "flexural strength" refers to the flexural strength according to DIN EN 1288-5:2000 (German version of: "Glass in Building - Determination of the flexural strength of glass - Part 5: Double-ring bending test on plate-shaped specimens with small test areas; EN 1288-5:2000").

[0026] According to a further advantageous development, the average thermal linear expansion coefficient in a temperature range between 20 °C and 700 °C is less than 1.1*10 -6< / K, in particular less than 1*10 -6< / K. This provides a particularly temperature-independent worktop with regard to its dimensions, which improves the handling of the worktop and the longevity of the worktop.

[0027] According to a further advantageous development, the worktop has an IR transmission in the wavelength range between 2300 nm and 2500 nm of more than 50%, preferably more than 60%, in particular more than 70%, and / or in the wavelength range between 3500 nm and 3700 nm of more than 50%, preferably more than 60%, in particular more than 70%, based on a worktop thickness of 4 mm. The advantage of this is a particularly effective transmission of heat in the aforementioned wavelength range through the worktop, so that, for example, heating elements arranged beneath the worktop can be operated in an energy-saving manner.

[0028] The worktop is made of a substrate comprising lithium, aluminum, and silicon, with keatite as the main crystal phase. This enables a worktop that is easy to manufacture, cost-effective, and flexible in its application.

[0029] According to a further advantageous development, the substrate has its own color to provide the color impression of the worktop. In other words, no dyes need to be added during the production of the worktop; the substrate is thus free of any added dyes, which simplifies the production of the worktop.

[0030] According to a further advantageous development, the worktop has at least one coating for homogenizing the color impression, in particular two coatings. This compensates for or minimizes any visually imperceptible differences in transmission or color impression.

[0031] According to a further advantageous development of the process, the continuous furnace is provided with five different groups of chambers. This allows for a simple design while simultaneously ensuring reliable control of the main chambers of the continuous furnace.

[0032] The duration of the second period is less than 50% of the duration of the first period, with the first holding temperature being provided between 700 °C and 850 °C and the second holding temperature being provided between 950 °C and 1200 °C. The advantage of this is that a high level of homogeneity, particularly in terms of color, of the worktop is achieved.

[0033] Further important features and advantages of the invention emerge from the subclaims, from the drawings, and from the associated description of the figures with reference to the drawings.

[0034] Preferred embodiments and embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components or elements.

[0035] In schematic form Figure 1 shows a worktop according to an embodiment of the present invention; Figure 2 shows steps of a method for producing a worktop according to an embodiment of the present invention; Figure 3 shows a continuous furnace in cross section for carrying out a method according to an embodiment of the present invention; and Figure 4 shows a temperature-time diagram of steps of a method according to an embodiment of the present invention.

[0036] Figure 1 shows a worktop according to an embodiment of the present invention.

[0037] In detail, Figure 1A rectangular worktop 1 is shown. The worktop 1 can also have any other shape, for example, trapezoidal, triangular, circular, or elliptical. Four arbitrarily selectable areas 2, 2'; 3, 3' are shown on the worktop 1. Each of the areas 2, 2', 3, 3' has an individual color impression in the L*-a*-b* color space. The color impression difference ΔE between any two areas of the four areas 2, 2', 3, 3' is less than 1.5 according to the formula Δ E = L 1 ∗ − L 2 ∗ 2 + a 1 ∗ − a 2 ∗ 2 + b 1 ∗ − b 2 ∗ 2 , where indices 1 and 2 denote the different values ​​for the selected areas according to the L*-a*-b* color space. If the dimensions of the areas are selected to be large, corresponding mean values ​​for the color impression L*, a*, b* of the respective area can be used.

[0038] Furthermore, the worktop 1 has an area 4 with a size of 2 m² and a thickness of 4 mm. The substrate for the worktop 1 is a glass-ceramic material of the Li-Al-Si type with a bright white appearance. This material has an average flexural strength of 144 MPa. The worktop 1 also has an average thermal expansion coefficient in the range between 20 °C and 700 °C of 1.05 10 -6 / K, which ensures high thermal stability, particularly in the area of ​​high-temperature cooking zones. The ceramization takes place at a maximum temperature of over 1000 °C. The color values ​​of the worktop 1 are L* = 95.4, a* = -0.44, and b* = -0.30. The color homogeneity over the entire surface of the worktop is ΔE = 0.12 and the Knoop hardness test results in a value of 619 HK 0.1 / 20 for the worktop.The infrared transmission is 60.5% at a wavelength of 3500 nm, based on a worktop thickness of 4.0 mm.

[0039] In a further embodiment not shown, the worktop 1 has the following properties: A glass-ceramic material of the Li-Al-Si type with a light gray-white appearance is used as the substrate for the worktop. The average flexural strength of the worktop is 160 MPa, and the average coefficient of thermal expansion in the range between 20 °C and 700 °C is 0.96-10 -6< / K. The ceramization again takes place at a maximum temperature of over 1000 °C. The color values ​​of the worktop are L* = 71.5, a* = -5.3, and b* = -12.5. The color homogeneity across the entire surface of the worktop is ΔE = 0.15.

[0040] In a further embodiment not shown, the worktop 1 has the following properties. A glass-ceramic material of the Li-Al-Si type with a light beige appearance is used as the substrate for the worktop. The flexural strength according to DIN EN 1288-5 averages 89 MPa, and the average coefficient of thermal expansion in the range between 20 °C and 700 °C is 0.93 10 -6 < / K. The ceramization takes place at a maximum temperature of over 1000 °C. The color values ​​of the worktop are L* = 87.3, a* = -2.2, and b* = 4.0. The color homogeneity over the entire surface is ΔE = 0.23. The infrared transmission, for example, is 72.8% at a wavelength of 2400 nm and 62.9% at a wavelength of 3600 nm, based on a worktop thickness of 4.0 mm.

[0041] Figure 2 shows steps of a method for manufacturing a worktop according to an embodiment of the present invention.

[0042] In detail, Figure 2 Steps of a method for producing a worktop according to any one of claims 1-11 are shown. The method particularly comprises a ceramization process for green glass.

[0043] In a first step S1, a substrate based on green glass is provided, here in the form of fused green glass. The green glass to be ceramized and / or the ceramized product from which the worktop is made has, in particular, a composition from the range: 60 - 73.0 wt.% SiO 2 , 15 - 25.0 wt.% Al 2 O 3 , 2.0 - 5.0 wt.% Li 2 O, 0 - 5.0 wt.% CaO + SrO + BaO, 0 - 5.0 wt.% TiO 2 , 0 - 5.0 wt.% ZrO 2 , 0 - 4.0 wt.% ZnO 0 - 3.0 wt.% Sb 2 O 3 , 0 - 3.0 wt.% MgO, 0 - 3.0 wt.% SnO 2 0 - 2.0 wt.% P 2 O 5 , 0 - 1.5 wt.% As 2 O 3 , 0 - 1.2 wt.% Na 2 O + K 2 O, the respective proportions preferably being within the ranges specified below, 0 - 1.0% by weight Na 2 O, 0 - 0.5% by weight K 2 O.

[0044] Since the process is applicable to a wide range of compositions, glass-ceramic compositions can also be produced from remelting phases, for example. Components from the above-specified composition range can then be completely omitted. A device can be provided for this purpose, which provides the green glass to be ceramized. In particular, this device is designed for melting and shaping the green glass.

[0045] In a further step S2, a continuous furnace is provided with a plurality of groups of chambers arranged one behind the other along a conveying direction of the substrate, each group having at least one chamber. The continuous furnace serves here in particular for ceramizing the starting product, green glass. However, the continuous furnace can also be used to further ceramize an already slightly ceramized HQMK glass ceramic to produce the final product in the form of a KMK glass ceramic. The continuous furnace can be designed so that the entire ceramization process can be carried out within 0.5 to 4 hours.

[0046] In a further step S3, the provided substrate is introduced into the continuous furnace for passing through it in the conveying direction such that the substrate is provided with a length in the conveying direction which is less than 75%, preferably less than 65%, in particular less than 60%, preferably less than 50% of the length in the conveying direction of at least one of the chambers of the continuous furnace, preferably each of the chambers of the continuous furnace.

[0047] In a further step S4, the temperature of the substrate is increased to a first holding temperature over a first period of time, in particular in a first group of chambers.

[0048] In a further step S5, the first holding temperature is maintained for a second period of time, in particular in a second group of chambers.

[0049] In a further step S6, the temperature is further increased to a second holding temperature over a third period of time, in particular in a third group of chambers.

[0050] In a further step S7, the second holding temperature is maintained for a fourth period of time, in particular in a fourth group of chambers.

[0051] In a further step S8, the substrate is cooled, in particular in a fifth group of chambers or outside the continuous furnace to form the worktop.

[0052] A group of chambers comprises one or more chambers.

[0053] Figure 3 shows a continuous furnace in cross section for carrying out a method according to an embodiment of the present invention.

[0054] In detail, Figure 3a continuous furnace 10 is shown. The continuous furnace 10 has five separate groups 21, 22, 23, 24, 25, each group having one or more chambers. Fig. 3 Each group 21, 22, 23, 24, 25 comprises - as shown schematically - only one chamber. Therefore, the terms "chamber" and "group" can be used interchangeably in the following, particularly in connection with the Fig. 3 be used synonymously.

[0055] Each chamber within groups 21, 22, 23, 24, 25 can be separately heated and / or cooled to a specific temperature. At least one group 21, 22, 23, 24, 25 of the continuous furnace 10 is configured for the volume crystallization of the green glass and / or the HQMK glass ceramic and, in particular, has heating devices 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b, 25a, 25b, which allow the heating of the green glass and / or the HQMK glass ceramic to be ceramized to 750°C to 1250°C.

[0056] Furthermore, a measuring and control device 12 is provided, which is designed to control the continuous furnace 10, in particular to detect temperature changes in the ceramizing green glass and / or the HQMK glass ceramic. The measuring and control device 12 then adjusts the temperature of the continuous furnace 10 accordingly, for example, within one second. A fast response time is particularly advantageous for effective control of the exothermic ceramization process.

[0057] Furthermore, a substrate 6 is conveyed in the conveying direction 100 through the continuous furnace 10 via a conveyor device 11, wherein the conveyor device 11 in particular has rollers for transporting and / or storing the substrate 6. The substrate 6 can also be in a suitable transport container (in Fig. 3not shown), for example on a carrier plate, a trough or the like. The substrate 6 has a length 200 in the conveying direction 100 which is less than 70% of the length of one or more of the chambers of the groups 21, 22, 23, 24, 25. If the chambers of a group 21, 22, 23, 24, 25 each act on the substrate 6 in the same way over time, the subdivision into separate chambers within the respective group 21, 22, 23, 24, 25 can be omitted and the substrate 6 can then have a length 200 in the conveying direction 100 which is less than 70% of the total length of the chambers of the respective group. If the chambers are of different lengths, the substrate 6 can then have a length 200 in the conveying direction 100 which is based on the shortest of all chambers.

[0058] Figure 4 shows a temperature-time diagram of steps of a method according to an embodiment of the present invention.

[0059] In detail, Figure 4 the time course of the temperature 400 is shown when the substrate 6 leaves the continuous furnace 10 according to Figure 3in the conveying direction 100. Starting from room temperature, the temperature is first increased over a time 301 to a first holding temperature 401, in particular at a rate between 5 °C / min and 40 °C / min, in particular at a rate between 10 °C / min and 30 °C / min. The first holding temperature 401 can be between 700 °C and 850 °C, in particular between 725 °C and 800 °C. The first holding temperature 401 is then maintained for a first holding time 302. The first holding time 302 can be between 5 min and 90 min, in particular between 10 min and 60 min. Subsequently, the temperature of the substrate 6 is increased over a time 303, starting from the first holding temperature 401, to a second, higher holding temperature 402, in particular at a rate between 5 °C / min and 40 °C / min, in particular at a rate between 10 °C / min and 30 °C / min. The second holding temperature 402 can be between 950 °C and 1200 °C, in particular between 980 °C and 1120 °C.This second holding temperature 402 is maintained for a certain second holding time 304. The second holding time 305 can be between 5 min and 45 min, in particular between 5 min and 25 min. Subsequently, the substrate 6 is cooled to room temperature for a certain time 305 to provide a worktop 1. Also shown in FIG. Figure 4 are the Figure 2 corresponding process steps S4-S8 of the Figure 2 the respective periods 301-305 of the Figure 4 assigned.

[0060] In summary, at least one of the embodiments of the invention has at least one of the following advantages: Highly homogeneous color impression. Highly homogeneous transmission in the visual and / or infrared range. Cost-effective production. Simple manufacturing. Long service life.

Claims

1. Kitchen equipment arrangement comprising a glass ceramic worktop (1), at least one energy transmission element (7) for cooking, in particular a heating element which is arranged below the worktop (1) and / or a communication element (8) for exchanging data, in particular having an apparatus which is arranged on or in the environment of the glass ceramic worktop (1), wherein the surface (4) of the worktop (1) is more than 1.25 m2, and wherein the worktop (1) is produced from a substrate (6) comprising lithium, aluminium and silicon with keatite as a main crystal phase, and wherein a first freely selectable region (2, 2') of the worktop (1) has a colour impression in the L*-a*-b* colour spectrum according to L1*, a1*, b1 and a second freely selectable region (3, 3') has a colour impression in the L*-a*-b* colour spectrum according to L2*, a2*, b2, aracterised in that the colour impression difference ΔE in the L*-a*-b* colour spectrum between the first and the second region (2, 2'; 3, 3') of the worktop (1) according to the formula ΔE L 1 ∗ − L 2 ∗ 2 + a 1 ∗ − a 2 ∗ 2 + b 1 ∗ − b 2 ∗ 2 is less than 2.0, preferably less than 1.0.

2. Kitchen equipment arrangement according to claim 1, characterised in that the colour impression difference ΔE is less than 0.25, in particular less than 0.2, preferably less than 0.13.

3. Kitchen equipment arrangement according to any one of claims 1 to 2, characterised in that the respective brightness value L* of the first and second region is in each case more than 65, preferably more than 80, in particular more than 90.

4. Kitchen equipment arrangement according to any one of claims 1 to 3, characterised in that the values of the respective green / red parameter a1*, a2* and / or the respective blue / yellow parameter b1*, b2* of the first and second range are less than 20.

5. Kitchen equipment arrangement according to any one of claims 1 to 4, characterised in that the surface-area (4) of the worktop (1) is more than 1.5 m2, preferably more than 2.5 m2.

6. Kitchen equipment arrangement according to any one of claims 1 to 5, characterised in that the hardness of the surface (5) of the worktop (1), measured as a Knoop hardness 0.1 / 20, is more than 600, preferably more than 650, in particular more than 700.

7. Kitchen equipment arrangement according to any one of claims 1 to 6, characterised in that the mean flexural strength of the worktop (1) is more than 80 MPa, in particular more than 100 MPa, preferably more than 130 MPa, in particular more than 165 MPa.

8. Kitchen equipment arrangement according to any one of claims 1 to 7, characterised in that the mean thermal length expansion coefficient is, in a temperature range between 20°C and 700°C, less than 1.1*10-6 / K, in particular less than 1*10-6 / K.

9. Kitchen equipment arrangement according to any one of claims 1 to 8, characterised in that the worktop (1), with respect to a thickness of the worktop of 4 mm, has an IR transmission in the wavelength range between 2300 nm and 2500 nm of more than 50%, preferably more than 60%, in particular more than 70%, and / or in the wavelength range between 3500 nm and 3700 nm of more than 50%, preferably more than 60%, in particular more than 70%.

10. Kitchen equipment arrangement according to any one of claims 1 to 9, characterised in that the substrate (6) has an intrinsic colour for providing the colour impression of the worktop.

11. Kitchen equipment arrangement according to any one of claims 1 to 10, characterised in that the worktop (1) has at least one coating for homogenisation of the colour impression, in particular two coatings.

12. Method for producing a worktop for a kitchen equipment arrangement according to any one of claims 1 to 11, characterised by the steps of: - providing (S1) a substrate (6) based on green glass, in particular in the form of molten green glass or a glass ceramic material produced from this green glass, preferably an HQMK glass ceramic material, - providing (S2) a continuous furnace (10) having a plurality of groups (21, 22, 23, 24, 25) of chambers which are arranged one behind the other in a conveying direction (100) of the substrate (6), and wherein each of the groups (21, 22, 23, 24, 25) comprises at least one chamber, - introducing (S3) the provided substrate (6) into the continuous furnace (10) in order to pass through it in the conveying direction (100) in such a manner that the substrate (6) is provided having a length (200) in the conveying direction (100) which is less than 75%, preferably less than 65%, in particular less than 60%, preferably less than 50% of the length (201) in the conveying direction (100) of at least one of the chambers of the continuous furnace (10), - increasing (S4) the temperature (400) of the substrate (6) up to a first holding temperature (401) over a first period of time (301), in particular in a first group (21) of chambers, - maintaining (S5) the first holding temperature (401) for a second period of time (302), in particular in a second group (22) of chambers, - further increasing (S6) the temperature (400) up to a second holding temperature (402) over a third period of time (303), in particular in a third group (23) of chambers, - maintaining (S7) the second holding temperature (402) for a fourth period of time (304), in particular in a fourth group (24) of chambers, and - cooling (S8) the substate (6) in order to form the worktop (1), in particular in a fifth group (25) of chambers or outside the continuous furnace (10), wherein as a duration for the second period of time (302) less than 50% of the duration of the first period of time (301) is selected and wherein the first holding temperature (401) is provided between 700°C and 850°C and wherein the second holding temperature (402) is provided between 950°C and 1200°C, and wherein the continuous furnace (10) is provided with five groups (21, 22, 23, 24, 25) of chambers.