WO2020260694A1 - Plaque de recouvrement, en particulier plaque pour chauffer des aliments et appareil pour chauffer des aliments - Google Patents

Plaque de recouvrement, en particulier plaque pour chauffer des aliments et appareil pour chauffer des aliments Download PDF

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Publication number
WO2020260694A1
WO2020260694A1 PCT/EP2020/068247 EP2020068247W WO2020260694A1 WO 2020260694 A1 WO2020260694 A1 WO 2020260694A1 EP 2020068247 W EP2020068247 W EP 2020068247W WO 2020260694 A1 WO2020260694 A1 WO 2020260694A1
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WO
WIPO (PCT)
Prior art keywords
cover plate
glass substrate
heating
heating food
glass
Prior art date
Application number
PCT/EP2020/068247
Other languages
German (de)
English (en)
Inventor
Evelin Weiss
Susanne Krüger
. Friedrich SIEBERS
Roland Dudek
Matthias Bockmeyer
Original Assignee
Schott Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Schott Ag filed Critical Schott Ag
Priority to CN202080047208.2A priority Critical patent/CN114040896B/zh
Priority to EP20736608.9A priority patent/EP3990408A1/fr
Priority to JP2021577559A priority patent/JP2022538318A/ja
Publication of WO2020260694A1 publication Critical patent/WO2020260694A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B27/00—Tempering or quenching glass products
    • C03B27/012—Tempering or quenching glass products by heat treatment, e.g. for crystallisation; Heat treatment of glass products before tempering by cooling
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B27/00—Tempering or quenching glass products
    • C03B27/02—Tempering or quenching glass products using liquid
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B27/00—Tempering or quenching glass products
    • C03B27/04—Tempering or quenching glass products using gas
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
    • C03C23/007—Other surface treatment of glass not in the form of fibres or filaments by thermal treatment
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
    • C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • C03C4/02—Compositions for glass with special properties for coloured glass

Definitions

  • Cover plate in particular plate for heating food, and device for heating food
  • the present application relates to a cover plate, such as, for example, a plate (or surface) for heating food, in particular a cooking, heating, roasting and / or grilling surface, and a device for heating food comprising such a surface
  • Cover plates which are temperature-resistant and serve as separating elements, such as protecting electronic components of a device, such as a device for heating food, and / or serving as viewing panels, for example in chimneys or ovens, are usually made of a glass ceramic with low thermal
  • Expansion coefficients formed such as those sold under the brand name CERAN®. This is necessary so that the cover plate, which is also referred to as a surface for heating food in a device for heating food, for example as a cooking, roasting, heating and / or grilling surface, can withstand the temperatures that are caused by the currently used heating devices or heating elements are generated.
  • induction heating elements also principally special glasses with slightly higher thermal expansion as the material of the cover plate. These are usually borosilicate glasses with an expansion coefficient of around 3.3 * 10 6 / K, also referred to as “borosilicate glasses 3.3”, which are commercially available as “Borofloat® 33", for example.
  • surfaces for heating food that is to say for example for cooking, roasting, heating and / or grilling, are also referred to in simplified terms as “cooking surfaces” or “hob”.
  • a cooking surface can also be referred to as a hotplate or, in general, a surface for heating food as a plate for heating food.
  • US 2015/274579 A1, US 2016/338152 A1 and US 2017/247284 A1 describe cooking appliances, cooking surfaces and / or hobs comprising cover plates made of temperature-resistant glass.
  • the international patent application WO 2018/225627 A1 describes a toughened glass with an expansion coefficient of 2 * 10 6 / K to 5 * 10 6 / K and a glass transition temperature of 560 ° C. or more.
  • the heating zones have a small distance of approx. 25 mm from the
  • the heatable areas or zones of a cover plate or plate or surface for heating food are also referred to in simplified form as cooking zones or heating zones.
  • cover plates comprising or at least partially or predominantly consisting of a glass, in particular a thermally toughened glass and / or a borosilicate glass, which can be used as a surface for heating
  • Food in a device for heating food and / or as a viewing window in hot applications for example as a fireplace viewing window or stove window, and which can be used in devices with normally powerful radiators and in which a reduced edge distance is possible compared to known cooking surfaces made of glass is.
  • One object of the invention is therefore to provide cover plates made of glass, in particular plates or surfaces for heating food made of glass and / or thermally highly resilient To provide viewing panes made of glass, for example for chimneys and / or stoves, which overcome or at least mitigate the aforementioned weaknesses of the prior art.
  • Another aspect of the invention relates to the provision of a glass which is suitable as an alternative to glass ceramic as a substrate material for a plate or, synonymously, a surface for heating food, in particular a cooking surface (or hotplate), and the weaknesses of the known glasses of the prior art overcomes or at least mitigates.
  • the object of the present invention consists in a first aspect in providing a cover plate which overcomes or at least mitigates the aforementioned weaknesses of the prior art, in particular a plate (or surface) for heating food, in particular by cooking, frying, heating and / or grilling, comprising a glass substrate with at least one heatable zone.
  • a second aspect of the present invention relates to the provision of a device for heating food comprising a cover plate, in particular a plate (or surface) for heating food, comprising a glass substrate with at least one heatable zone, which overcomes the weaknesses of the prior art or at least reduces, preferably a device that can be manufactured inexpensively and / or has improved operator safety.
  • a third aspect relates to the use of such a cover plate.
  • the invention consequently relates to a cover plate, in particular a plate (or surface) for heating food, in particular by cooking, roasting, heating and / or grilling, comprising a glass substrate with at least one heatable zone, the glass substrate comprising a vitreous material comprising the following components in% by weight:
  • the flexural strength of the thermally pre-stressed glass substrate in particular through wear and tear of a surface, simulated by sanding with 220 SiC, preferably has a safety characteristic of flexural strength, defined as the mean value of the strength distribution reduced by three standard deviations, of at least 90 MPa.
  • the standard deviation was 3 to 5 MPa in each case.
  • the glass substrate has a vitreous material which comprises the following components in% by weight:
  • K 2 0 0 to 8 particularly preferably greater than 0
  • Nd 2 03 0 to 0.5, preferably 0 to 0.3
  • Sb 2 03 0 to 1.6, preferably 0 to 0.6 CI 0 to 0.5 and optionally at least one further coloring oxide from the group Fe 2 03 and / or CoO and optionally further color oxides, in particular NiO, Mn0 2 , Cr 2 03, the proportion of the further coloring oxides, incl optionally further color oxides, in total between 0% by weight and 5% by weight.
  • the glass substrate has a vitreous material which comprises the following components in% by weight:
  • Si0 2 62 to 80 preferably 63 to 80, particularly preferably 63 to 79
  • Li 2 0 0 to 4.2 preferably 1 to 4.1, particularly preferably 2 to 4.1
  • K 2 0 0 to 8 preferably 0 to 1, particularly preferably 0 to 0.2, particularly preferably greater than 0
  • MgO 0 to 9.8, preferably 0 to 2, particularly preferably 0 to 1.1
  • CaO 0 to 9.8, preferably 0 to 1, particularly preferably 0 to 0.2
  • Zr0 2 0 to 2.5, preferably 0 to 1.9, particularly preferably greater than 0
  • Mn0 2 0 to 0.5, preferably 0 to 0.3
  • Nd 2 Ü3 0 to 0.5, preferably 0 to 0.3, particularly preferably 0 to 0.25
  • AS 2 Ü3 0 to 0.9, preferably 0 to 0.85 Sb 2 0 3 0 to 1.6, preferably 0 to 0.6 and optionally at least one further coloring oxide from the group Fe 2 C> 3 and / or CoO and optionally further color oxides, in particular NiO, Mn0 2 , Cr 2 03 , the proportion of the further coloring oxides, including any further color oxides, being in total between 0% by weight and 5% by weight.
  • the glass substrate has a glassy material, the glass substrate comprising a glassy material comprising the following components in% by weight:
  • Si0 2 61 to 80 preferably 61 to 79, particularly preferably 62 to 79
  • La 2 03 0 to 0.5 preferably free of La 2 C> 3 except for unavoidable traces
  • a coloring oxide is understood to mean an oxide which, in a glass matrix, uses coloring ions to color the glass in volume by absorption.
  • the coloring ions of the coloring oxide are distributed in the glass matrix, comparable coloring ions in a liquid or solution.
  • the volume of the glass is colored by the coloring oxide, so that it is referred to as volume colored.
  • coloring by coloring ions in particular coloring metal ions
  • Such colorations by pigment and / or by a coating which, for example, can change the scattering behavior of a glass, are not volume coloring in the sense of the present disclosure.
  • the volume coloring does not change the scattering behavior of the glass.
  • the glass according to embodiments, to be transparent and uncoloured, that is to say, apart from unavoidable traces, it does not contain any coloring oxides.
  • Such inevitable traces are typically 500 ppm or less.
  • the preparation of food by means of heating is understood in particular to mean cooking, for example using cookware such as a saucepan, frying, for example using roasting utensils such as a frying pan or roaster, grilling and / or heating food.
  • Food includes solid, ok
  • fluid substances such as water, or mixtures of solid and fluid substances such as dough.
  • a device for heating food can be, for example, a cooking device which comprises a so-called cooking surface.
  • This cooking surface in turn comprises a glassy substrate or glass substrate and optionally coatings which are arranged on a surface of the surface and / or can furthermore be refined and / or reworked, in particular, for example, have machined and / or faceted edges and / or bores.
  • the device can comprise further components, in particular electronic components.
  • a surface for heating food therefore comprises a vitreous substrate or glass substrate and optionally coatings which are arranged on a surface of the surface or the substrate and / or can furthermore be refined and / or reworked.
  • a substrate is understood to mean a product which can be reworked and / or refined, in particular by treating surfaces and / or edges, such as, for example, the faceting of edge surfaces and / or the application of coatings.
  • a cover plate is understood to mean a refined substrate.
  • the heatable zone of a cover plate for example a surface for heating food, is preferably an area of the substrate. If the surface for heating food is a cooking surface, such a heatable zone can also be referred to as a “cooking zone”.
  • a disk-shaped design of a product is understood to mean that the spatial expansion of the product in two
  • Spatial directions of a Cartesian coordinate system is at least one order of magnitude larger than in the third spatial direction.
  • This third, hence the smallest spatial dimension, is usually also called the thickness of the product, for example a substrate or a surface for preparing food by heating, the other two spatial directions are usually referred to as its length and width.
  • a disk-shaped substrate can be designed both flat or flat and also curved and can also be designed as a flat or flat disk or as a curved disk.
  • the main surfaces or main surfaces of the substrate and, accordingly, also of the cover plate or area are determined by the length and the width of the plate. These are the top and bottom of the substrate or surface.
  • the upper side of the substrate or the cover plate or surface is that main surface of the substrate, the cover plate or the surface which faces a user during operational use, for example for heating food.
  • the underside is that main surface of the substrate or of the cover plate or of the surface which faces away from the user in operational use of such a plate. If, within the scope of the present application, from a “surface” of the substrate or the area for heating
  • Food means a main surface (also main surface), i.e. the top or the bottom of the surface or the substrate.
  • top side can also be understood as the side of a substrate or of the cover plate or surface which has or can have markings, for example
  • Cooking zone markings or functional coatings intended to improve the usability of a device for example haptic coatings.
  • the underside is the side of the substrate which, for example, can face electronic components.
  • Coatings on the underside therefore generally have different properties than top-side coatings.
  • the underside can also be referred to as the back and the top as the front.
  • T g is understood to mean the transformation or glass transition temperature of a material.
  • the transformation temperature T g is determined by the intersection of the Tangents to the two branches of the expansion curve when measured with a heating rate of 5K / min. This corresponds to a measurement according to ISO 7884-8 or DIN 52324.
  • linear thermal expansion coefficient a is specified in the range from 20-300 ° C., unless stated otherwise.
  • the terms a and O20-300 are used synonymously in the context of this invention.
  • the specified value is the nominal mean thermal coefficient of linear expansion according to ISO 7991, which is determined in static measurements.
  • vitreous material or a glass is understood to mean an amorphous material which is obtained from a melting process, preferably with subsequent hot shaping such as rolling, floating or drawing.
  • the strength is also essentially determined by the surface damage that can typically occur in daily use on a surface, in particular the upper side of a surface for heating food and / or a glass substrate which is covered by such a surface, after some use a practice-relevant state of use prior to commissioning through a use-simulating one
  • Surface change in particular a sanding of the area of the surface or the glass substrate, which comprises at least the area between the heating zones and the outer edge of the cover plate, for example with bonded SiC grains of grain size 220 according to DIN ISO 6344.
  • the sanding takes place perpendicular or parallel to the outer edge of the plate, in particular as will be described in more detail below. Then the heatable zone that is adjacent to or below the sanded area is put into operation.
  • an emery is carried out and in each case as emery both for the emery to determine the Resistance to temperature differences as well as for the sanding to determine a
  • Safety value as well as for the determination of the bending or bending strength the emery sheet or sandpaper from the manufacturer VSM with the article no. CP918A and a grit P220 used.
  • the type of grain of the sandpaper or sandpaper used is silicon carbide and the sandpaper or sheet complies with the DIN ISO 6344 standard.
  • the bond is a fully synthetic resin bond and the carrier material is light latex paper (A-paper) .
  • the sample body 1 has the thickness of the cover plate 100 from which it was removed and thus a thickness of between 2.8 mm and 6.3 mm, with no difference in the result of the sanding being able to be recognized for different thicknesses
  • the change in the surface made by sanding was thus independent of the thickness of the sample body 1 and thus of the cover plate 100.
  • the sample body 1 was removed from the cover plate 100 or isolated from it before compressive or compressive prestresses were introduced into the cover plate 100. After the sample body 1 had been separated, compressive stresses were introduced into it together with the cover plate 100 from which it was removed by thermal prestressing. In this case, the sample body 1 in each case went through the same pretensioning process as the cover plate 100, preferably together with it, and thus had the same compressive or compressive pretensioning as this. This was the case in particular before sanding for the subject matter of claim 1, claim 16 and claim 22.
  • 5a shows an arrangement for carrying out a first process step in the method for sanding a sample body 1 of a cover plate 100 for the subsequent determination of the resistance to temperature differences mentioned in claim 16 and the minimum distance a between the outer edge of the cover plate and the edge of the at least one heatable zone, which differs from the sanding mentioned in claim 1 for determining the bending or bending strength, as explained in more detail below.
  • a sample body 1 is produced from the cover plate 100 described here, which has not yet been subjected to any surface changes, such as in particular
  • this sample body 1 hereby also includes the respective respective surface compressive stresses disclosed in the present case, which are within the scope of the present
  • Disclosure can also be referred to as surface compressive prestresses.
  • An emery sheet 2 measuring 65 mm ⁇ 30 mm is evenly loaded by a weight 3 that covers the entire surface and has a flat underside, so that the contact pressure per surface is 2 N / cn.
  • Emery sheet 2 in its entirety over the outer edge 4 (or the outer edge) 4 of the
  • the length of the total distance covered by the emery sheet 2, thus the sanding distance, is 200 mm in each case and leads into an overflow distance outside the specimen 1, which is directly connected to the specimen 1.
  • This movement of the first process or method step has the result that after the end of the sanding, the sanding sheet 2 has left the test specimen 1.
  • Sample body 1 of the cover plate 100 for example thus over the simulated
  • the edge of the cooking surface in addition to being able to apply a uniform contact pressure, can, if necessary, be suitable for achieving the values disclosed here
  • Cover plate 100 are positioned, which compensates for the height difference between the sample body 1 of the cover plate 100 and the surroundings of the sample body 1 and forms the aforementioned overflow path.
  • the emery sheet 2 is oriented for the process or method steps of the method for introducing a surface change, in particular the emery, shown in Figures 5a, 5b and 6a, so that its longer side of 65 mm is perpendicular to the outer edge 4 of the plate, thus the outer edge 4 of the sample body 1 of the cover plate 100 is located.
  • the longer side of 65 mm of the sanding sheet 2 is oriented parallel to the plate outer edge 4.
  • the thickness of the auxiliary plate 5 must be adapted accordingly.
  • the sanding process described above is repeated with a second, also unused sanding sheet, in the same position, as shown again in FIG. 5b.
  • the emery path is kept constant over a length of 200mm.
  • the “0” position or start position of the “emery section” begins in particular in the heatable zone, thus at least in specimen 1 at a distance of 200mm from the edge of specimen 1 and ends at the cold outer edge 4, with an emery section that runs at right angles to the middle of the heated zone, which extends to the heated zone in question.
  • the sanding to determine a safety parameter based on the flexural or bending strength is carried out as follows.
  • the sample body 1 has an area of 100 ⁇ 100 mm with a thickness of 4 mm and the length of the sanding path is 100 mm.
  • the first step shown in FIG. 6a is carried out as described above with regard to the sanding shown in FIG. 5a to determine the resistance to temperature differences.
  • the second method or process step shown in FIG. 6b differs therefrom.
  • the second step of this sanding process is the one described above
  • the sanding process is repeated with a second, also as yet unused sanding sheet, the sample body 1 being rotated by 90 ° beforehand, however, and being moved over a sanding path with a length of 100 mm running parallel to the edge 4, so that a perpendicularly intersecting track of sandpaper is on the sample body 1 adjusts.
  • the temperature difference resistance (TUF) T max in particular also to determine the minimum distance a mentioned in claim 16 between the outer edge of the cover plate and the edge of the at least one heatable zone can be determined as follows : i) presenting the prestressed cover plate;
  • adjacent second edge 1 is 10 mm, i.e. that the distance between the intersection of the diagonals of the emery paper and the second edge is 125 mm, and the type of grain of the emery paper is silicon carbide and has a grain size of P220, which is bound to a light latex paper (A-paper) with a fully synthetic resin bond, and where the sandpaper complies with the DIN ISO 6344 standard;
  • Claim 1 and Claim 22 are determined as follows: i) measuring the thermal prestress of the cover plate by means of a scattered light polariscope, the “Sculp-05” device from “Glasstress”;
  • the type of grain of the first emery paper is silicon carbide and has a grain size of P220, which is bound to a light latex paper (A paper) with a fully synthetic resin bond, and the first emery paper corresponds to the DIN ISO 6344 standard;
  • the type of grain of the second emery paper is silicon carbide and has a grain size of P220, which is bound to a light latex paper (A-paper) with a fully synthetic resin bond, and the second emery paper corresponds to the DIN ISO 6344 standard;
  • Safety value of the flexural strength in particular also for the purposes of claim 21 such as can be determined as described above, whereby a defined, in particular use-simulating surface change is introduced by the abrasion described, after introduction of the surface change a test of the glass substrate of the cover plate 100, in particular a test of the bending or bending strength, preferably measured using the double ring method according to EN 1288- 5, is carried out, and based on the result of the test, a safety characteristic is determined and assigned to the cover plate.
  • This safety characteristic value is preferably the flexural strength, defined as the mean value of the strength distribution reduced by three standard deviations, and has at least 90 MPa as the minimum safety characteristic value for the cover plates disclosed in the present case.
  • the use-simulating surface change can be caused by
  • Sanding in particular by sanding as described above for claim 1, essentially corresponds to an average use of the cover plate or the device for heating food of approximately three years of use.
  • Preload in particular the thermal surface compressive preload, in the glass substrate encompassed by the cover plate or one encompassed by the cover plate
  • Safety characteristic value is used, the above method step being carried out until the safety characteristic value then determined is greater than or equal to the specified minimum safety characteristic value. Commissioning takes place by installing the surface or illustrative plate in a device for heating food or placing the surface or illustrative plate for heating food on an inductive heater of a device for heating food, with the distance between in the latter case the radiator and the underside of the plate corresponds to the distance that is usually used in devices for heating
  • Food is used, for example, a cooking or roasting utensil or - vessel which has a flat bottom and a bottom diameter which deviates from the diameter of the heatable zone by at most 5 mm.
  • the bottom diameter of the vessel used can therefore be up to 5 mm larger or up to 5 mm smaller than the diameter of the heatable zone.
  • the heatable zone heats up and runs through a temperature-time curve at the hottest point on the upper side of the surface or, more clearly, the plate, which is also shown schematically in FIG.
  • the upper side is the side of the surface or, more clearly, the plate which is in contact with the dishes or vessel.
  • the temperature-time curve reaches a first maximum within a maximum of 5 minutes, which is also referred to as the overshoot temperature.
  • the outer edge of the plate at room temperature leads to tensile stresses in the vicinity of the outer edge, the level of which depends on the level of the temperature difference
  • Material parameters of the substrate and the distance between the edge of the heatable zone and the outer edge of the plate depends.
  • the relevant material parameters are in particular the linear thermal expansion coefficient, the modulus of elasticity E and the Poisson's ratio m.
  • a reduced distance between the edge of the heatable zone and the outer edge of the plate at the same temperature increases the tensile stresses near the edge and thus the risk of breakage.
  • the temperature differential resistance denotes that maximum temperature on the upper side of the plate at which the plate breaks for the first time under the condition of a minimum distance of the edge of the heatable zone from the outer edge of the plate of 25 mm.
  • a cover plate which has a correspondingly sufficient resistance to temperature differences in such a start-up test is generally not only suitable as a cover plate in a device for heating food, but can also be used, for example, as a heater cover.
  • a glass is referred to as volume colored in particular when it is colored, for example, by coloring metal ions.
  • a transparent glass is understood to mean, in particular, a glass which comprises no or only slightly scattering components.
  • a glass can thus be designed to be transparent, volume-colored, but of course also be transparent and uncolored.
  • a lighting device is understood to mean, in particular, a device or a product which is designed as a lighting means or comprises a lighting means, for example an LED.
  • a display element is understood to mean an electronically controlled element which outputs optical signals.
  • the display element can be designed as a matrix or segment display, in particular as a graphic display.
  • the chemical resistance of glasses is generally given in three classes, a distinction being made between the hydrolysis, acid and alkali resistance of the glass.
  • the acid resistance of a glass or the acid class is determined in the context of the present disclosure in accordance with the regulation of DIN 12116.
  • the class is classified according to the amount of extracted glass components, the best class again being class 1.
  • the alkali resistance of a glass or the alkali class is determined in the context of the present disclosure in accordance with ISO 695.
  • the best class that is to say the one with the highest alkali resistance, is again class 1.
  • the chemical resistance of the glass is given by an indication of the class of hydrolytic resistance H, acid resistance S and alkali resistance L of at least 2, 3, 3.
  • H hydrolytic resistance
  • S acid resistance
  • alkali resistance L alkali resistance
  • the cover plate By designing the cover plate in such a way that it comprises a glass substrate comprising the aforementioned components, the glass substrate is designed as a thermally toughenable glass substrate.
  • the glass substrate is designed in such a way that it can be subjected to high thermal prestressing, and thus sufficient through thermal prestressing
  • Durability of the cover plate can be achieved. This is particularly important in the event that the plate is intended as a surface for heating food and therefore sufficient operational safety of a device for heating food should be ensured including such a surface. Such a configuration increases the
  • the cover plate or the surface as well as the device for heating food.
  • the glass substrate can be manufactured inexpensively.
  • the glass substrate is designed such that the flexural strength of the thermally pre-stressed glass substrate due to wear of a surface, simulated by sanding with 220 SiC, a safety characteristic of the flexural strength, is defined as that of three
  • Standard deviation has a reduced mean value of the strength distribution of at least 90 MPa.
  • the sanding with 220 SiC simulates in a reproducible way scratches that arise from the use of the cover plate.
  • the tops of surfaces or plates for heating food by hard-grained contaminants that are rubbed over the top of the plate for example by contaminants on the bottom of a vessel or dishes for heating food, or by cleaning, for example with a scraper and / or with abrasive cleaning agents and / or utensils, for example abrasive sponges
  • the glass substrate is designed such that it is a glass substrate that is resistant to mechanical abrasion. This resistance of the glass substrate to mechanical abrasion is to be understood here in such a way that the glass substrate may still have scratches, for example, but these do not critically reduce the strength of the glass substrate, in particular the flexural strength.
  • a cover plate comprising such a glass substrate or even consisting of such a glass substrate is less prone to failure due to breakage in the application case, the glass substrate generally being in the form of a thermally prestressed glass substrate in the application case.
  • the application here includes, for example, the operation of a cooking device or, more generally, a device for heating food, if the cover plate is designed as a surface for heating food and is used in such a device.
  • the use of the cover plate is by no means limited to its use as a surface for heating food, for example as a cooking surface, but the use of the cover plate is generally conceivable for areas of application in which a significant temperature gradient occurs in the edge area of the cover plate.
  • Areas of application therefore include, for example, covers for lamps and / or radiators, inner panes of pyrolysis ovens or the like.
  • the glass substrate is thermally prestressed, the thermal surface compressive prestress being at least 65 MPa.
  • the substrate has a coefficient a ⁇ / (1 -m) which is between at least 0.28 MPa / K and at most 0.53 MPa / K, where a is the mean coefficient of thermal expansion in the temperature range between 20 ° C and 300 ° C, E the modulus of elasticity and m the Poisson's ratio of the glass.
  • Poisson's ratio m is also called Poisson's number.
  • the cover plate is made possible in which, for example, normally powerful heating elements can be used in a device for heating food, so that in particular the parboiling performance is also possible for example, in a cooking surface or a cooking device is not very small.
  • a cover plate or cooking surface configured in this way, a design is possible in which the at least one heatable zone has a minimum distance of only 25 mm from the outer edge of the cover plate or plate (or surface) for heating food or cooking surface.
  • the cover plate is preferably designed such that the glass substrate has a temperature difference resistance of at least 310 ° C. with a minimum distance of 25 mm from the edge of the at least one heatable zone to the outer edge of the cover plate.
  • Such a configuration is particularly advantageous for the use of the cover plate as a surface or plate for heating food, especially when heating elements (or radiators) with a specific power of at least 8 W / cn are used in the device for heating food and the distance between the heating zone and the outer edge of the cover plate or surface for heating food is no more than 25 mm.
  • the available surface can be used optimally, i.e. there are no large cold areas or edge gaps on the surface of the surface for heating food.
  • This is of particular relevance for the European domestic appliance market, since here usually four heating elements - corresponding to four heating zones of the glass substrate or the cover plate or surface - are arranged in the appliance.
  • a heatable zone comprises a first, smaller zone and a second heatable zone which surrounds the first, the first, smaller zone being heated first and the second zone being able to be switched on if necessary.
  • Induction heating elements are particularly preferred as heating elements.
  • the preloading process consists of three sections.
  • the glass substrate is heated to a temperature T which is 100 K to 150 K above the glass transition temperature T g .
  • the second section consists of a holding time after which the temperature T is homogeneously present in the entire glass substrate due to temperature equalization.
  • the glass substrate is cooled on both sides, usually by blowing a gaseous medium or a mixture of gaseous and liquid phases, which results in a surface compressive stress of at least 65 MPa in the entire glass substrate after room temperature has been reached.
  • a fundamentally high temperability of the glass substrate or the cover plate or the surface or plate for heating food is therefore necessary to deal with the temperature differences that occur during the operation of the device for heating food, such as those between the heatable zone and the outer edge of the plate to withstand without breaking.
  • the maximum temperature T MA x is determined in the heated zone. This capability assumes that the tensile stresses occurring in the cold edge area of the cover plate due to the temperature difference between the hot, heatable zone and the adjacent cold outer edge of the cover plate are lower than the strength at the same point.
  • the maximum allowable temperature T of the heated heatable zone ma x are within the scope of the present disclosure in particular the surface temperature of the cover plate, and that the temperature of the top of the cover plate.
  • the top side of the cover plate is the side of the cover plate which faces the user during operational use, that is to say the side which is designed to be
  • this top side can be designed so that it has further elements, such as
  • the marking of the edge of the heatable zones (which are also referred to as cooking zone markings in the case of a hotplate or cooking surface, for example).
  • the surface temperature of the cover plate in the heated heatable zone is usually the highest temperature. This is particularly the case when the heating element of a device for heating food than
  • Induction heating element is designed, because in this case the heating takes place in particular via appropriate cookware.
  • T max is described as the maximum permissible temperature on the surface, namely the top of the cover plate, of the heated, heatable zone.
  • the strength in the cold edge area of the cover plate, OR is made up of the flexural strength s G defined by typical usage injuries and the additional strength due to the thermal surface compressive prestress sn:
  • the strength in the cold edge area of the cover plate must be greater than the thermally induced tensile stresses s z occurring there. These are defined by the material parameters modulus of elasticity (E), thermal expansion coefficient (a) and Poisson's ratio (m) as well as by the spatial distribution of the temperature on the cover plate and there in particular the distance between the edge of the heated zone and the adjacent cold outer edge of the cover plate. This distance is referred to as a.
  • E modulus of elasticity
  • a thermal expansion coefficient
  • m Poisson's ratio
  • Temperature difference between the hot, heatable zone and the adjacent cold outer edge of the cover plate can be summarized as follows:
  • the maximum absolute temperature of the heated heatable zone T ma x is obtained directly from the addition of the temperature of the cold edge of the cover plate Trand which lies in the rapid heating process at room temperature of about 25 ° C, and the just described
  • Tmax This is the value for Tmax, which was determined for a distance a of the edge of the heatable zone from the outer edge of the cover plate of 25 mm. This distance a is also referred to below as “edge distance” or “distance” for short.
  • the maximum temperature of the heatable zone can therefore also be used as a function of the distance a, ie
  • T max f (a)
  • T max f (a)
  • the edge distance a thus appears in the prefactors of the integrals, namely quadratically in the denominator, which directly illustrates the stress-reducing effect of a larger edge distance.
  • the first integral component which depicts the temperature profile of the heatable zone, is to be regarded as a constant regardless of the edge distance and when the edge distance is varied.
  • the second integral component which maps the edge area, depends on the temperature profile in the edge area, which in principle has an exponentially decreasing characteristic and can usually be resolved with simple means.
  • Glass compositions which are suitable for cover plates according to the present disclosure are characterized in that in the distance-temperature diagram according to FIG. 4 they lie below a limit straight line which is given by the following formula: preferably below the limit straight line, given by the formula:
  • a again denotes the minimum distance between the edge of the heatable zone and the outer edge of the cover plate in millimeters and T max the maximum temperature in the heated heatable zone.
  • the so-called position in the distance-temperature diagram ensures an improved break resistance compared to the prior art with regard to temperature differences that occur between the heated heatable zone and the adjacent cold outer edge of the cover plate.
  • Temperature control that does not have a maximum temperature of 290 ° C and preferably 310 ° C exceed the increased design freedom with regard to the arrangement of heatable zones on the plate for preparing food, as required, for example, in European models with a minimum distance of the heatable zone to the outer edge of the cover plate of 25 mm.
  • the glass substrate comprises a glassy material comprising the following components in% by weight:
  • Si0 2 63 to 80 preferably 63 to 79, particularly preferably 64 to 79
  • MgO 0 to 9.8, preferably 0 to 1.1
  • Sb2Ü3 O to 1.6, preferably 0 to 0.6 and optionally at least one further coloring oxide from the group Fe 2 03 and / or CoO and optionally further color oxides, in particular NiO, Mh0 2 , 0G 2 03, the proportion of further coloring oxides, including any other color oxides, in total between 0% by weight and 5% by weight.
  • a glass substrate comprises a glassy material, this particularly includes the case that the glass substrate predominantly, i.e. at least 50% by weight, or essentially, i.e. at least 90% by weight, or even entirely consists of this material.
  • the cover plate can be designed as a plate or disk made of the vitreous material, optionally provided with refinements such as coatings.
  • compositions are to be understood such that the components listed make up at least 98% by weight, generally 99% by weight of the total composition.
  • Compounds of a variety of elements such as B. F, the alkalis Rb, Cs, rare earths or elements such as Zr and Hf, but also Fe, Sr, Zn are common impurities in glass production, especially due to the batch raw materials used on an industrial scale. Insofar as a proportion of 0% by weight is specified for components, this means that the relevant component is not used in the raw material mixture.
  • the glass substrate has a thickness between 2.8 mm and 6.3 mm.
  • the glass substrate is less thick, sufficient strength is no longer guaranteed.
  • the strength can in principle be achieved by using a greater thickness of the glass substrate and corresponding to the area.
  • this not only has the disadvantage that more material has to be used in this way and therefore the costs of the substrate increase accordingly, but a greater thickness also leads to more weight. Therefore, the maximum thickness of the glass substrate is limited and is preferably not more than 6.3 mm.
  • the glass substrate has a chemical resistance F1, S, L of at least 2, 3, 3 or better, the chemical resistance as hydrolytic class H according to DIN ISO 719, the acid class S according to DIN 121 16 and the alkali class L according to ISO 695 is determined.
  • Such a design of the cover plate as a chemically resistant cover plate is advantageous because in this way damage to the cover plate surface, which can be kept as low as possible from abrasion of the surface due to corrosion by food, such as water or vinegar or the like. It is also advantageous if, especially in the case of direct contact of a food with the cover plate, for example when using the cover plate as a surface for heating food, for example when grilling a food directly on the surface, as far as possible no substances from the glassy material of the cover plate or Surface can be detached.
  • the glass substrate is transparent and uncolored, characterized by a transmission in the visible wavelength range of the electromagnetic spectrum ivi S of at least 85.0%, based on a glass thickness of 4.0 mm. ivis is understood here as the standard color value Y in the wavelength range 380 nm to 780 nm, based on standard light D65, observer 2 ° and a glass thickness of 4.0 mm.
  • the glass substrate preferably has a neutral transmission characteristic.
  • the glass substrate is transparent, volume-colored, the glass substrate preferably being neutral
  • the person skilled in the art will adjust the composition of the glass substrate in such a way that the desired degree of transmission is achieved, in particular by setting the amount of coloring components accordingly.
  • a design of the glass substrate as a transparent, uncolored glass substrate can be advantageous if, for example, the arrangement of display elements and / or
  • Lighting devices for example as a display of the status of a surface for heating food or the device for heating food, is desired below the surface or below the glass substrate and display elements and / or Lighting devices can therefore be viewed by the operator through the surface or the glass substrate.
  • display elements and / or Lighting devices can therefore be viewed by the operator through the surface or the glass substrate.
  • Lighting devices is necessary, for example to display the temperature via the setting of a color locus of a lighting device and therefore to increase the
  • the glass substrate may even be transparent, volume-colored.
  • the view of components of the device that are arranged below the glass substrate or the surface for heating food can be reduced.
  • the glass substrate is preferably designed in such a way that it is color-neutral
  • the glass preferably has an achromatic color point, i.e. the saturation value C * of the CIEL * a * b * color space is a maximum of 10.0 and preferably less than 4.0, where C * is defined as
  • C * Va * 2 + b * 2 , based on standard light D65, an observer at a viewing angle of 2 ° and a glass thickness of 4.0 mm.
  • the description of the preferred achromatic color point can also be made by specifying the CIE color coordinates x and y with the limits 0.26 ⁇ x ⁇ 0.38 and 0.27 ⁇ y ⁇ 0.42.
  • the glass substrate has a quotient a ⁇ / (1 -m) which is between at least 0.28 MPa / K and at most 0.53 MPa / K, where a is the mean coefficient of thermal expansion in temperature between 20 ° C and 300 ° C, E the modulus of elasticity and m the Poisson's ratio of the glass.
  • At least one coating is arranged in at least one area of at least one surface of the cover plate.
  • a coating can be arranged in at least one area of the top and / or the bottom of the cover plate.
  • the coating can be, for example, a so-called decorative layer or decoration arranged on the upper side of the surface, which can be in the form of a logo and / or in the form of a marking of the at least one heated zone, or alternatively or additionally a masking layer arranged on the underside of the cover plate, which is designed in particular with a transparent, uncoloured cover plate to cover or hide components arranged below the cover plate, for example a device for heating food, especially when the cover plate is used as a surface for heating food.
  • a second aspect relates to a device for heating food, in particular by cooking, frying, heating and / or grilling, which comprises a cover plate, such as a plate (or surface) for heating food, according to the preceding embodiments, and at least one of the at least one heatable zone of the cover plate or the plate or surface for heating food associated heating element, in particular an induction heating element, wherein the heating element has an edge distance to the edge of the cover plate of at most 25 mm and wherein the heating element has a specific heating power of at least 8 W / cm 2 and preferably of a maximum of 15 W / cm 2 .
  • induction heating elements in particular are particularly suitable, since in this way only low temperature loads occur on the glass substrate or cover plate or surface.
  • the use of induction heating elements also increases the rate
  • Cover plate can actually be heated. In other words stands by one
  • Cover plate available as a heatable zone or heatable zones. This allows in particular the integration of four heating zones or in particular cooking zones for one
  • Cover plate which corresponds to the usual dimensions of a cooking surface, for example. It is also possible to use powerful heating elements at the same time, so that sufficient parboiling performance is guaranteed.
  • the device comprises a sensor, such as a touch sensor on a capacitive or optical basis and / or a temperature sensor, and / or the device comprises a lighting device, such as an LED, and / or a display element, like an electro-optical display element.
  • Lighting devices and / or display elements which, for example, can transmit information about the state of the device, for example the temperature in the heated state, to the operator via preferably optical or electro-optical signals, is further improved.
  • the substrate and / or the surface for heating food has an IR transmission over the entire surface or in areas preferred for this purpose, which for each of the Wavelengths 950 nm and 1600 nm is between 25 and 80%, each based on a thickness of 4.0 mm.
  • the device comprises a means with which one can be connected to an IT means, such as a computer, a tablet PC, and / or a smartphone, the means preferably configured in this way is that a wireless connection can be established, and particularly preferably the IT means can be connected to the device in such a way that the cooking appliance can be controlled with the IT means, and / or the means as IT means is designed, which is designed to be connectable, and wherein the cooking device is controllable with the IT means.
  • an IT means such as a computer, a tablet PC, and / or a smartphone
  • Yet another aspect of the invention relates to the use of a cover plate according to embodiments as a surface for heating food, as a lamp or
  • Emitter cover as an inner pane of a pyrolytic oven, as an oven pane, as a fireplace viewing window or as an oven viewing pane or as a heat shield to shield hot surroundings.
  • the relevance of the temperature difference resistance is based on the following
  • Embodiments 1 to 7 and the comparative example are further explained.
  • the composition of the glass and its material properties are first described.
  • a cover plate, here a plate or surface for heating food, made of the corresponding glass is then considered, the plate or surface comprising a glass substrate which is thermally pre-stressed.
  • Embodiment 1 is a diagrammatic representation of Embodiment 1:
  • Embodiment 1 describes an embodiment of a cover plate and a device for heating food comprising a surface or plate for heating food comprising a glass substrate.
  • This glass has the following material properties (Tab. 1 b):
  • T g denotes the glass transition temperature, measured in accordance with DIN 52324.
  • C * denotes the saturation value of the CIEL * a * b * color space, where C * is defined as
  • C * yja * 2 + b * 2 based on standard light D65, an observer at a viewing angle of 2 ° and a glass thickness of 4.0 mm.
  • ivi S is understood here as the standard color value Y in the wavelength range 380 nm to 780 nm, based on standard light D65, observer 2 ° and a glass thickness of 4.0 mm.
  • a glass substrate is produced with this glass and thermally toughened.
  • the cover plate according to embodiment 1 comprises this glass substrate with at least one heatable zone.
  • the maximum possible or permissible surface temperature of the upper side of the substrate or the plate in the heatable zone also referred to in Table 1c as the maximum temperature of the heatable zone, TM 3X , is therefore a function of the minimum distance a of the edge of the heatable zone from the outer edge of the cover plate, can also be referred to as TMax (a), as is done in Table 1 c.
  • TMax a
  • This maximum temperature is therefore to be understood as a temperature limit value, i.e. the maximum permissible temperature.
  • the temperature difference resistance of 357 ° C determined under the conditions of a conventional, damaged top of a cover plate, such as the top of a hotplate or cooking surface or more generally a plate for heating food, and with a minimum distance of the edge of the heated zone from the outer edge of the plate 25 mm is sufficient to allow the desired design freedom.
  • composition according to Table 1 a was changed to such an extent by small admixtures of further elements that volume-colored variants resulted which decisively reduced the transparency, although a desirable color neutrality was maintained.
  • the admixtures are listed in Table 1 d (in% by weight):
  • Embodiment 2 describes a further embodiment of a cover plate and a device for heating food comprising a cover plate, here a surface or plate for heating food, comprising a glass substrate.
  • This glass has the following material properties (Tab.2b):
  • a glass substrate is produced with this glass and thermally toughened.
  • the cover plate according to Example 2 comprises this glass substrate with at least one heatable zone.
  • Strength characteristics, especially the flexural strength, are summarized in Tab.2c:
  • Tab.2c The temperature difference resistance of 321 ° C, determined under the conditions of a customary, damaged top of a cover plate, such as the top of a hotplate or cooking surface or, more generally, of a plate for heating food, and with a minimum distance of the edge of the heated zone from the outer edge the 25 mm plate is sufficient to allow the desired freedom of design. This means that the technical design of a device for heating food, for example with a space-saving integration of four heatable zones, is possible in this way.
  • Embodiment 3 is a diagrammatic representation of Embodiment 3
  • Embodiment 3 describes yet another embodiment of a cover plate and a device for heating food comprising a cover plate, here a surface or plate for heating food, comprising a glass substrate.
  • a cover plate here a surface or plate for heating food, comprising a glass substrate.
  • Glass with the following composition is used (in% by weight; Tab.3a):
  • This glass has the following material properties (Tab.3b):
  • a glass substrate is produced with this glass and thermally toughened.
  • the cover plate according to embodiment 3 comprises this glass substrate with at least one heatable zone.
  • the temperature difference resistance of 310 ° C determined under the conditions of a conventional, damaged upper side of a cover plate, such as the upper side of a hotplate or cooking surface or more generally a plate for heating food, and with a minimum distance of the edge of the heated zone from the outer edge of the plate 25 mm is sufficient to allow the desired design freedom. This means that the technical design of a device for heating food, for example with a space-saving integration of four heatable zones, is possible in this way.
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • Embodiment 4 relates to a further cover plate and a further device for heating food comprising a cover plate, here a surface or plate for heating food, comprising a glass substrate.
  • This glass has the following material properties (Tab.4b):
  • a glass substrate is produced with this glass and thermally toughened.
  • the cover plate according to embodiment 4 comprises this glass substrate with a heatable zone.
  • the temperature difference resistance of 361 ° C determined under the conditions of a conventional, damaged top of a cover plate, such as the top of a hotplate or cooking surface or more generally a plate for heating food, and with a minimum distance of the edge of the heated zone from the outer edge of the plate 25 mm is sufficient to allow the desired design freedom.
  • a device for heating food for example with a space-saving integration of four heatable zones, is possible in this way.
  • the corresponding properties of three further examples are given in the table below for Examples 5, 6 and 7.
  • the comparative example relates to a cover plate and a device for heating food comprising a cover plate, here a surface or plate for heating food, comprising a glass substrate.
  • This glass has the following material properties (Tab.5b):
  • a glass substrate is produced with this glass and thermally toughened.
  • the cover plate according to the comparative example comprises this glass substrate with a heatable zone.
  • Strength characteristics, especially the flexural strength, are summarized in Tab.5c:
  • the temperature difference resistance of 272 ° C determined under the conditions of a conventional, damaged upper side of a cover plate, such as the upper side of a hotplate or cooking surface or more generally a plate for heating food, and with a minimum distance of the edge of the heated zone from the outer edge of the plate 25 mm is not sufficient to withstand the overshoot temperatures of at least 310 ° C without breaking. To avoid breakage, that would be
  • the minimum distance between the edge of the heatable zone and the outer edge of the plate should be increased significantly, namely by at least another 20 mm.
  • a heating element with a significantly lower output would have to be used. However, this would lead to an undesirable impairment of the cooking or heating performance.
  • Fig. 2 shows a temperature-time curve of the top of the cover plate in a
  • FIG. 5a shows an arrangement for performing a first process step in FIG
  • 5b shows an arrangement for carrying out a second process step in the
  • FIG. 6a shows an arrangement for performing a first process step in FIG.
  • 6b shows an arrangement for performing a second process step in
  • a cover plate according to the present disclosure is shown schematically and not true to scale by way of example.
  • This cover plate 100 here has four heatable zones 102, for example.
  • the edge 103 of the heatable zone 102 is shown here as an example by black circles.
  • the distance ai 0 between the edge 103 of the heatable zone 102 arranged in the upper left area of the cover plate 100 and the outer edge 101 of the cover plate 100 is shown.
  • the distance ai 0 is the distance a for the heatable zone 102 “top left” (Io).
  • the distance a is generally within the scope of the present disclosure the shortest connection between the outer edge 101 (or synonymously outer edge) of the cover plate 100 and the edge 103 of a heatable zone 102, regardless of their respective shape, such as circular, elliptical or rectangular.
  • the distance a can be different for each heatable zone 102, for example in the present case the — not shown — distance ai u for the heatable zone 102, which is shown here at the bottom left, would be greater than the distance ai 0, ma if the T x for all heated zones 102 is the same - this can for example be the case if all Fleiz implant used the same
  • Fig. 2 is a schematic representation of the temperature-time curve for the
  • FIG. 3 shows, for embodiment 4, the determination of the flexural strength after sanding a thermally prestressed substrate with 220 sandpaper.
  • the x-axis denotes the flexural strength in MPa, measured in the double ring test.
  • the y-axis denotes the
  • Probability of failure (cumulative frequency).
  • the flexural strength is used as part of the present disclosure denotes the bending strength measured with the double ring method according to EN 1288-5.
  • the distance a in mm is plotted on the y-axis and the maximum surface temperature T max in the heated heatable zone is plotted on the x-axis.
  • the limit straight line 300 is also shown.
  • the curve 301 for the exemplary embodiment 1, the curve 302 for the exemplary embodiment 2, the curve 303 for the exemplary embodiment 3, the curve 304 for the exemplary embodiment 4 and the curve 305 for the comparative example are also designated.
  • the curve 305 for the comparative example lies above the limiting straight line 300.
  • the limiting straight line 300 is given here by equation (11), preferably by equation (12).
  • the present disclosure also describes a device for heating food according to embodiments comprising a cover plate according to embodiments, in particular comprising at least one heatable zone, with the cover plate preferably being characterized by a permissible maximum temperature T max , preferably a permissible one, after use-simulating sanding with 220 SiC maximum surface temperature, preferably a permissible maximum temperature of the top of the cover plate, the probability of breakage failure of the cover plate being less than 0.13%, the minimum distance a between the outer edge of the cover plate and the edge of the at least one heatable zone, given in millimeters, the Inequality prefers the inequality and particularly prefers the inequality the inequality is particularly preferred
  • the present disclosure also relates to a cover plate according to FIG.
  • the cover plate is characterized, in particular after use-simulating sanding with 220 SiC, by a maximum permissible temperature T max , preferably a maximum permissible surface temperature, preferably a maximum permissible temperature of the top of the cover plate, the probability of breakage of the cover plate being less than 0.13 %, the minimum distance a between the outer edge of the cover plate and the edge of the at least one heatable zone, given in millimeters, the inequality prefers the inequality and particularly prefers the inequality the inequality is particularly preferred
  • composition areas specified above individual composition areas are also disclosed independently and in this way are disclosed even without the further composition areas of a corresponding composition additionally specified.

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Abstract

La présente invention concerne une plaque de recouvrement, en particulier une plaque pour chauffer des aliments, en particulier par cuisson, friture, chauffage et/ou cuisson au gril, comprenant un substrat en verre avec au moins une zone chauffante, le substrat en verre comprenant un matériau vitreux et un appareil pour chauffer des aliments, en particulier par cuisson, friture, chauffage et/ou cuisson au gril, comprenant la plaque de recouvrement, ainsi qu'un procédé pour déterminer une caractéristique de sécurité, en particulier pour la plaque de recouvrement et un procédé pour fournir la plaque de recouvrement ou l'appareil pour chauffer des aliments.
PCT/EP2020/068247 2019-06-28 2020-06-29 Plaque de recouvrement, en particulier plaque pour chauffer des aliments et appareil pour chauffer des aliments WO2020260694A1 (fr)

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CN202080047208.2A CN114040896B (zh) 2019-06-28 2020-06-29 盖板、尤其用于加热食物的板，以及用于加热食物的设备
EP20736608.9A EP3990408A1 (fr) 2019-06-28 2020-06-29 Plaque de recouvrement, en particulier plaque pour chauffer des aliments et appareil pour chauffer des aliments
JP2021577559A JP2022538318A (ja) 2019-06-28 2020-06-29 カバープレート、特に食品加熱プレート、および食品加熱機器

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DE102019117480.5A DE102019117480A1 (de) 2019-06-28 2019-06-28 Abdeckplatte, insbesondere Platte zum Erhitzen von Lebensmitteln, sowie Gerät zum Erhitzen von Lebensmitteln
DE102019117480.5 2019-06-28

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EP3990408A1 (fr) 2022-05-04

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