EP3655367A1

EP3655367A1 - Blower box for thermal prestressing of glass panes

Info

Publication number: EP3655367A1
Application number: EP18726164.9A
Authority: EP
Inventors: Peter Schillings; Achim ZEICHNER; Luigi MAZZEO; Lutz GEHNEN; Bernd Schneider
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS
Priority date: 2017-07-21
Filing date: 2018-05-28
Publication date: 2020-05-27
Also published as: CA3070116A1; WO2019015835A1; KR102342004B1; JP6955082B2; BR112019022414A2; JP2020527533A; CN109562974A; KR20200019982A; US20210101822A1; RU2735597C1; MA49614A; DE202018006726U1

Abstract

The present invention relates to a blower box (1) for the thermal prestressing of glass panes, comprising - a stationary part having a cavity (2a) and a gas feed line (3) connected to the cavity (2) and - at least one closure element (5, 15) having a plurality of nozzles connected to the cavity (2) for applying an airflow to a surface of a glass pane (I), wherein - the at least one closure element (5, 15) is connected to the stationary part at least via a connection element (6) of variable length, and - the at least one closure element (5, 15) is movable relative to the stationary part so that the distance between the closure element and the stationary part is variable, and - the blower box (1) is equipped with means (7) for moving the at least one closure element (5, 15).

Description

Blow box for the thermal tempering of glass panes

The invention relates to a blow box and a device containing this for the thermal tempering of glass panes, as well as a biasing method performed therewith.

The thermal curing of glass has long been known. It is often referred to as thermal tempering or annealing. By way of example, reference may be had to the patent documents GB 505188 A, DE 710690 A, DE 808880 B, DE 1056333 A from the 1930s to the 1950s. A heated to just below softening temperature glass is thereby acted upon by an air flow, which leads to a rapid cooling (quenching) of the glass. As a result, a characteristic stress profile is formed in the glass pane, wherein compressive stresses predominate on the surfaces and tensile stresses in the core of the glass pane. This has an influence on the mechanical properties of the glass pane in two ways. First, the breakage stability of the disc is increased and it can withstand higher loads than an uncured disc. Secondly, a glass break after penetration of the central tensile stress zone (such as damage by a sharp stone or intentional destruction with a sharp emergency hammer) is not in the form of large sharp-edged shards, but in the form of small, blunt fragments, reducing the risk of injury is significantly reduced.

Due to the properties described above, thermally toughened glass panes are used as so-called single-pane safety glass in the vehicle area, in particular as rear windows and side windows. Especially in the case of passenger cars, the discs are typically bent. The bending and tempering takes place in combination: the disk is softened by heating, brought into the desired curved shape and then acted upon by the cooling air flow, wherein the bias voltage is generated. In this case, so-called blow boxes (quench box, quench head) are used, which is supplied by strong fans, the air flow and split the air flow as evenly as possible on the disk surface.

There are several types of blow boxes known. Relatively simple blow boxes are closed by a nozzle plate in which the nozzles, by means of which the glass sheet is exposed to air, are distributed in the manner of a two-dimensional pattern. Blow boxes of this type are known for example from GB 505188 A, US 4662926 A and EP 0002055 A1. at More complex blow boxes, the air flow is divided into different channels, each with a nozzle bar are completed. The nozzle bars have a single row of nozzles which are directed at the glass panel and which redistribute the air flow of each channel and impinge the glass sheet with the now distributed over a large area air flow. Blow boxes of this type with nozzle strips are disclosed for example in DE 3612720 C2, DE 3924402 C1 and WO 2016054482 A1.

If the glass panes to be prestressed are flat or cylindrical, ie bent only along one spatial direction, then the blow boxes together with nozzles (with regard to their distance from the glass pane) can remain stationary while the glass panes to be prestressed successively into the intermediate space between the blow boxes and again out of the intermediate space to get promoted. In this case, such blow boxes are known which are connected with their nozzles via connecting elements of variable length. As a result, the positioning of the nozzles can be adjusted, so that disk types of different shape, that is, in particular different dimension and different bending, can be biased with the same device. The positioning of the nozzles is then initially set to the type of disc to be pretensioned. The tempering of the disc of this type of disc then takes place for the entire production series with this setting, wherein the distance of the nozzles from the biasing position of the glass remains invariable. Blow boxes of this type are known, for example, from EP0421784A1, US4314836A, US4142882 and DE1056333B1. The transport of the glass sheets can be carried horizontally on rolls, as in EP0421784A1, suspended vertically on a pair of pliers, as in US4142882 and DE1056333B1, or lying horizontally on a frame mold, as in US4314836A.

From US6722160B1 a device for biasing curved glass sheets is known, wherein the curved glass sheet is transported by means of rollers through an array of nozzles. At a given time, only a subset of all nozzles impinge on the glass sheet with an air flow. The positioning of those rollers and nozzles, which are assigned to the glass pane at a certain moment, adapted by simultaneous vertical displacement to the shape of the disc. A similar device is known from JP200418951 1A. Since the adaptation to the disk shape is achieved by a relative displacement of the rollers relative to one another, this adaptation relates only to the disk curvature along the spatial direction perpendicular to the extension direction of the individual rollers. An adaptation to the disc curvature along the spatial direction parallel to the extension direction of the individual rollers is not possible. As a result, this device is also optimally usable only for cylindrically curved discs.

Since vehicle windows are typically bent in both directions in space, that is, as it were formed boiler-like, it is not possible to move them for biasing between two stationary blow boxes. Namely, the nozzle exit surface has a curvature which is adapted to that of the glass pane, so that all nozzle openings have substantially the same distance to the disk surface. In order to retract the curved disk between the complementary bent blow boxes, the blow boxes must be in a relatively widely spaced state. In this state, the blow boxes would then be at least locally too far from the disk surface, which would reduce the biasing efficiency too much. The nozzle openings must be located as close as possible to the disk surface in order to achieve optimum pretensioning efficiency. The bent glass sheet is therefore typically driven between an upper and a lower blow box, which then approximates the blow boxes to each other and to the disk surfaces for biasing. It is crucial that the approach takes place as quickly as possible so that the glass does not cool significantly before pre-stressing. After tempering, the blow boxes are removed again to move the glass sheet out of the gap. The overall device with the two blow boxes is often referred to as a bias station.

The constant movement of the heavy blow boxes means a high load on the pretensioning device, which requires complex movement mechanisms and is energy-consuming. In addition, each blow box is only suitable for a specific type of pane, on whose geometric shape (size and curvature) the nozzle plates or the nozzle strips are tuned. If another disc type is to be preloaded, the replacement of the complete blow boxes is necessary, which is time-consuming and labor-intensive. The present invention has for its object to provide a blow box for the thermal toughening glass sheets, which is more flexible, the cost of converting the biasing device between different types of disc significantly reduced and relies on less complex mechanical movement mechanisms. The object is achieved by a blow box according to independent claim 1. Preferred embodiments are evident from the dependent claims.

The blow box according to the invention serves to act on the surface of a glass sheet for thermal toughening. The blow box is a device having an internal cavity and a gas supply line which is connected to the cavity and via which a gas flow into the cavity in the interior of the blow box can be initiated. The gas flow is typically generated by means of one or more fans in series. Preferably, the gas supply line can be closed, for example, by means of a slide or a flap, so that the gas flow into the inner cavity can be interrupted without switching off the fans themselves.

The blow box according to the invention comprises a stationary part which has a cavity and a gas supply line connected to the cavity. The cavity is surrounded by a cover, with which the gas supply line is connected and which has at least one outlet opening. The blow box also comprises at least one movable closure element which is provided to close the at least one outlet opening and which is equipped with a plurality of nozzles. The nozzles are connected to the cavity or connected to the cavity so that gas can flow from the cavity through the nozzles to impart air flow to the surface of a glass sheet.

The blow box thus divides the gas flow from the gas supply line with a comparatively small cross section over the nozzles to a large effective area. The nozzle orifices are discrete exit points of gas, but present in large numbers and evenly distributed so that all areas of the surface are cooled substantially simultaneously and uniformly to provide the disk with a homogeneous bias.

The nozzles are bores or ducts that extend through the entire closure element. Each nozzle has an inlet opening (nozzle inlet) through which the gas stream enters the nozzle and an opposite outlet opening (nozzle opening) through which the gas stream exits the nozzle (and the entire blow box). The surface of the closure element with the inlet openings facing the cavity of the blow box and that surface facing away with the nozzle openings thereof and facing the intended use of the glass. Through the nozzle openings, the surface of a Glass pane as intended subjected to an air flow. The nozzles may advantageously have a section adjoining the inlet opening and tapering in the direction of the outlet opening in order to guide the air efficiently and fluidically into the respective nozzle.

According to the invention the closure element is not rigidly connected to the stationary part of the blow box. Instead, the closure element is movable relative to the stationary part, away from the stationary part and vice versa towards the stationary part. The distance between the closure element and the stationary part is thus variable. If the nozzle openings are to be approximated to a glass pane for pretensioning, it is no longer necessary to move the entire blow box. Instead, the stationary part can remain stationary and only the closure element is approximated to the glass pane, in which its distance from the stationary part is increased. After biasing, the closure member is removed from the glass sheet again by reducing its distance from the stationary part, and the glass sheet can be moved out of the space between the blow boxes. In order to maintain the gas flow between the cavity and the closure element, the closure element is connected to the stationary part via a connection element which has a variable length. The connecting element can thus adapt to the respectively set distance between the closure element and the stationary part.

For biasing bent glass panes closure elements are used, which are adapted to the contour of the glass pane to ensure over the entire wafer surface, the substantially same small distance between the glass pane and nozzles. In conventional blow boxes, the closure element is connected directly to the other blow box with the cavity. Therefore, the contour of the outlet opening of the cavity must be exactly adapted to the contour of the closure element. As a result, the entire blow box is only suitable for a specific type of pane. If the production line is to be changed to another type of disc with a different curvature, the entire blow boxes must be replaced.

In contrast, the present invention allows a more flexible use of the blow boxes. Since the closure element is not connected directly to the stationary part of the blow box, but via the connecting element of variable length, it is no longer necessary in the blow box according to the invention that the contour of the outlet opening of the cavity is precisely adapted to the contour of the closure element. this makes possible it to equip the same stationary part of the blow box with different closure elements. If the disc type to be pretensioned is to be changed, it is therefore no longer necessary to exchange the complete blow box. Instead, only the closure element must be changed. As a result, the tool costs and the necessary storage space are significantly reduced because only one set of closure elements must be manufactured and stored for each type of disc instead of a complete Blaskastens. In addition, the effort during conversion is reduced. The biasing device is also simplified and more energy efficient, because the movement of the relatively light closure element is less complicated by machine than the movement of the heavy blow boxes, so that mechanically less strong control elements are necessary. These are great advantages of the present invention.

The relative arrangement of the entirety of all nozzles to each other is preferably constant and not changeable. The spanned by the totality of all nozzle openings surface is thus fixed and does not change during the movement of the at least one closure element. The closure element or the entirety of all closure elements is adapted to apply the glass pane through the entirety of all nozzles simultaneously with the cooling gas flow. The invention is applicable to various types of blow boxes. In a first embodiment, the closure element is a nozzle plate. The blow box has only a single closure element. The nozzle plate is an element, typically a plate, which comprises the entirety of the nozzles of the blow box. The nozzles are formed as holes or passages through the plate. The nozzles are arranged in the manner of a two-dimensional pattern in the plate, for example in a plurality of rows and a plurality of columns. The single nozzle plate is connected to the stationary part of the blow box by means of a single variable length connector to complete the cavity. This type of blow box is relatively simple and therefore inexpensive to manufacture.

The nozzle plate can be smooth or corrugated, with the nozzles preferably being arranged on the corrugation peaks in the corrugated configuration. The troughs then provide drainage channels for the emanated gas. In a second embodiment, nozzle strips are used as closure elements, as is customary in more complex blow boxes, with which achieves a higher biasing efficiency can be. To the cavity are in this case, the gas supply line typically opposite, a plurality of channels connected, in which the gas stream is divided during operation. Within the stationary part of the blow box, there is thus a transition from the cavity into a plurality of channels in order to divide the gas flow from the cavity into the channels. The channels may also be referred to as nozzle lands, fins or ribs. The channels are typically of elongated, substantially rectangular cross-section, the longer dimension being substantially equal to the width of the cavity and the shorter dimension being in the range of 8 cm to 15 cm. Typically, the channels are arranged parallel to each other. The number of channels is typically from 10 to 50. The channels are typically formed by sheets.

The cavity is preferably formed wedge-like. The boundary of the cavity adjacent to the channels can be described as two side surfaces which converge at an acute angle. The channels are typically perpendicular to the connecting line of said side surfaces. Consequently, the length of a channel is not constant, but increases from the center to the sides, so that the channel's entrance port connected to the cavity is wedge-shaped and spans the exit port into a smooth, typically curved surface. The exit openings of all channels typically form in common smooth, curved surface. The described wedge-shaped configuration of the cavity and the described arrangement of the channels, the gas stream is particularly efficiently divided into the channels and it results over the entire effective area very homogeneous gas flow.

Each channel is closed at its end opposite the cavity with a nozzle bar. However, this compound is not rigid according to the invention. Instead, each nozzle bar is connected to its associated channel (that is, the channel to which it is connected and terminates) via a connector having a variable length. The connecting element can thus adapt to the respectively set distance between nozzle bar and channel. Each channel is thus assigned its own connection element and a nozzle bar.

The nozzle bar has a plurality of passages, which are referred to as nozzles. Through the nozzles of the nozzle bar, the gas flow of the channel is divided again. The nozzle bar preferably has a single row of nozzle openings which are arranged substantially along a line. The row of nozzle openings preferably extends over at least 80% of the length of the nozzle bar. All nozzle strips of a blow box are preferably rigidly connected to each other, so that they are movable together. The connection can be achieved for example via one or more cross braces or by a circumferential frame-like bracket. By the means for moving the closure element, the entirety of the nozzle strips is then moved simultaneously, wherein the required relative arrangement of the nozzle strips is fixed and fixed by the cross braces or the holder.

The at least one connecting element of variable length can be attached directly or indirectly to the associated closure element. In the case of an indirect connection, a further element is arranged between the actual closure element, that is to say in particular the nozzle plate or nozzle strip, and the connection element, for example a gas channel or fastening element for the closure element. The connecting element is then attached to the further element, which in turn is connected to the closure element. The fastening element can be for example a fastening rail into which the closure element is inserted,

The following statements relate, unless stated otherwise, to the invention in general form, regardless of whether the closure element is designed as a nozzle plate, nozzle bar or in any other way.

The closure element preferably contains aluminum or steel and is preferably made of the said materials. These materials are easy to work with and provide advantageous stability in long-term use. The closure element may also contain or be made of a plastic, which is preferably stable up to a temperature of about 250 ° C. The plastic must have the necessary temperature stability for the purpose, the outflowing gas has temperatures of over 200 ° C. Suitable plastics are, for example, ethylene-propylene copolymer (EPM), polyimide or polytetrafluoroethylene (PTFE).

The nozzle openings preferably have a diameter of 4 mm to 15 mm, more preferably of 5 mm to 10 mm, most preferably of 6 mm to 8 mm, for example 6 mm or 8 mm. The distance between adjacent nozzle openings is preferably from 10 mm to 50 mm, particularly preferably from 20 mm to 40 mm, for example 30 mm. This achieves good pretensioning results. By far the distance between the respective centers of the nozzle openings is referred to here. The length and width of the closure element depends on the design of the blow box. Typical values for the length of a nozzle bar (measured along the extension direction of the nozzle row) are from 70 cm to 150 cm and for the width / depth (measured perpendicular to the length in the plane of the nozzle openings) of 8 mm to 15 mm, preferably 10 mm up to 12 mm. Typical values for the length of a nozzle plate are also from 70 cm to 150 cm and for the width from 20 cm to 150 cm.

The blow box is also provided with means for moving the closure element or the closure elements to change the distance of the at least one closure element to the stationary part. For this purpose, cylinders can be used, which are driven by servomotors, such as servomotors, which have the advantage that they can be moved very quickly and accurately. Alternatively, however, it is also possible, for example, to use pneumatically or hydraulically driven cylinders. The outlet opening of the stationary part of a blow box is typically rectangular in plan view, in particular rectangular or trapezoidal, so that preferably four drive cylinders are used, one of which is arranged at a corner of the blow box. However, depending on the intended use, other geometries of the outlet opening are also conceivable, for example round or oval outlet cross sections.

The means for moving the closure element are particularly suitable for changing the distance between the closure element or the entirety of all closure elements to the stationary part, without changing the relative arrangement of the nozzles to each other. The area spanned by the entirety of the nozzle openings of a blow box surface, which is preferably adapted to the shape of the glass pane to be pretensioned, thus remains constant during the movement of the closure element. The said surface is in a particularly advantageous embodiment three-dimensional, ie curved along both spatial directions. This can also be called a spherical curvature.

The means for moving the closure element are particularly suitable and intended to approximate the at least one closure element to each glass pane to be pretensioned and to remove it again from the glass pane following the pretensioning, preferably to bring the closure element closer to the next glass pane to be pretensioned. The movement of the closure element or the entirety of all closure elements preferably takes place simultaneously. The connecting element of variable length is in a preferred embodiment, a bellows. In order not to significantly attenuate the gas flow, the bellows should be made of a material as low as possible gas permeability. Suitable materials include canvas, leather or steel, which is spring-like or formed as a fabric. The thickness of the material of the bellows is preferably from 0.2 mm to 5 mm, more preferably from 0.5 mm to 3 mm, which on the one hand sufficient stability and mechanical durability and good gas tightness is ensured and on the other hand, an advantageous flexibility and deformability. In the case of a nozzle plate as a closure element, a single bellows is used, which is fastened on the one hand in the peripheral side edge of the nozzle plate or on a further element located between connecting element and nozzle plate and on the other hand in the region of the outlet opening of the cover which surrounds the cavity of the stationary part. In the case of nozzle strips as closure elements, a separate bellows is used for each nozzle bar, which is fastened on the one hand in the region of the peripheral side edge of the nozzle bar or on a further element located between connecting element and nozzle bar and on the other hand in the region of the outlet opening of the associated channel boundary. In a further preferred embodiment, the connecting element is designed as a rigid tube and the connecting element and the stationary part of the blow box are telescopically guided into one another and displaceable to each other to make the distance between the closure element and the stationary part changeable. The tube typically has a quadrangular cross-section, corresponding to the shape of the nozzle plate or nozzle bar. The tube is typically formed from a sheet of metal, such as steel or aluminum, and preferably has a wall thickness of 0.5 mm to 3 mm. In the case of a nozzle plate as a closure element, a single tube is used, which is directly or indirectly connected on the one hand to the region of the peripheral side edge of the nozzle plate. On the other hand, the tube is inserted into the cover surrounding the cavity of the stationary part so as to protrude into the cover and the cavity, or alternatively plugged onto the cover so that the cover protrudes into the tube. In the case of nozzle strips as closure elements, a separate tube is used for each nozzle bar, which is plugged into the associated channel output, so that it projects into the channel, or alternatively plugged onto the associated channel output, so that the channel boundary protrudes into the tube. The variant in which the cover of the stationary part or the Channel boundaries protrude into the tube or tubes, may be preferred because the flow cross-section for the gas flow at the transition from stationary part to the connecting element in this case expands, resulting in lower flow losses. In any case, the tube and the associated stationary part should be arranged as flush as possible with the smallest possible distance from each other so as not to cause a significant pressure drop of the gas flow.

If a rigid tube is used as the connecting element, in addition, a bellows can be used, which surrounds the telescopic construction. The bellows is then not used in this case as a connecting element of variable length, but serves to protect the telescopic construction from dirt or moisture.

The invention also includes an apparatus for thermally tempering glass sheets. The device comprises a first blow box according to the invention and a second blow box according to the invention, which are arranged opposite one another, so that their closure elements and their nozzles face each other. The blow boxes are spaced apart so that a glass sheet can be placed between them. Typically, the nozzles of the first blow box (upper blow box) substantially downwardly and the nozzles of the second blow box (lower blow box) substantially upwards. Then, a glass pane can advantageously be moved horizontally between the blow boxes. The nozzles are aligned approximately perpendicular to the glass surface. The apparatus further comprises means for moving a glass sheet adapted to move a glass sheet into the space between the two blow boxes and out of said space again. For this purpose, for example, a rail, roller or treadmill system can be used. In a preferred embodiment, the means for moving the glass also comprise a frame shape, on which the glass is mounted during transport. The frame shape has a circumferential, frame-like bearing surface on which the side edge of the glass sheet rests, while the main part of the disk surface.

The blow boxes themselves, ie their stationary parts, according to the invention are not intended to be moved during the biasing. The device may nevertheless comprise means for changing the distance between the first and second blow boxes. For example, servo motors, so that they can be moved away from each other. The distance between the blow boxes can then be increased, for example, for maintenance purposes or for retrofitting the closure element. The device is particularly suitable and intended to approach the closure elements to each vorzuspannende glass, which is arranged in the space between the blow boxes, and to remove the closure elements after the biasing again from the glass pane (that is, the distance of the closure elements to the glass to zoom in) to move the glass back out of the space between the blow boxes. The movement of the closure element or the entirety of all closure elements of a blow box preferably takes place simultaneously. The device is particularly suitable and provided to apply the glass sheet through the entirety of all nozzles of the blow boxes simultaneously with the cooling gas stream.

The relative arrangement of the nozzle openings of the blow boxes is preferably adapted to the shape of the disc to be pretensioned. The nozzle openings of a blow box thereby span a convexly curved surface and the nozzle openings of the opposite blow box a concave curved surface. These surfaces preferably remain constant during the movement of the closure elements, so the relative arrangements of the nozzles of a blow box to one another does not change. The entirety of all the nozzles of a blow box is moved simultaneously on the glass to or from the glass pane, without changing their relative arrangement to each other. The relative arrangement of the nozzles of a blow box to each other and the surface spanned by their nozzle openings is thus identical in the further spaced from the glass pane state (in which the glass is retracted or extended) and in the approximate state (in which the actual biasing occurs). The strength of the curvature also depends on the shape of the disk. During pretensioning, the convex blow box faces the concave surface of the disc and the concave blow box faces the convex surface. Thus, the nozzle opening can be positioned closer to the glass surface, which increases the biasing efficiency. Since the discs are usually transported with upwardly facing concave surface to the biasing station, the upper blow box is preferably convex and the lower concave configured. The distance of the nozzle exits to the glass surface can be set exactly to a desired value by the means for moving the at least one closure element. The device is preferably suitable and provided for biasing curved glass panes three-dimensionally (ie along both spatial directions). Such glass sheet can also be referred to as spherically bent, in contrast to cylindrically curved glass sheets, which are bent only along a spatial direction.

The invention also includes an arrangement for thermally tempering glass panes, comprising the device according to the invention and a glass pane arranged between the two blow boxes.

The invention also includes a method for thermally tempering a glass sheet, wherein

(A) a heated glass pane, which has two main surfaces and a peripheral side edge, is arranged flat between a first blow box according to the invention and a second blow box according to the invention, so that the two main surfaces can be acted upon by a gas stream,

(B) then the closure elements of the two blow boxes are approximated to the glass and

(C) are then applied to the two main surfaces of the glass sheet by means of the two blow boxes with a gas stream, so that the glass sheet is cooled.

After pretensioning, the closure elements of the two blow boxes are removed from the glass pane again. Subsequently, the glass sheet is moved out of the space between the glass sheets. The method is not a continuous process in which the glass sheets are continuously moved through the space between the blow boxes without staying there. Instead, the glass sheet is placed in the space, remains there during the pretensioning and is then moved out of the gap again. Then the next glass pane can be placed between the blow boxes. The movement of the closure elements toward the glass pane and then back away from the glass pane takes place separately for each individual glass pane. The movement of the closure element or the entirety of all closure elements of a blow box preferably takes place simultaneously. During tempering, the glass sheet is acted upon by the entirety of all nozzles of the blow boxes simultaneously with the cooling gas stream. During the actual tempering, the glass pane is typically oscillated back and forth, so that the air flow emerging from a nozzle is not always applied to the same location of the glass pane, but a more homogeneous distribution of the cooling effect over the wafer surface is achieved.

Preferably, in step (b), only the shutter elements of the blow boxes are moved, while the stationary parts of the blow boxes remain stationary and stationary.

The glass sheet is preferably transported on rollers, rails or a treadmill between the blow boxes. In an advantageous embodiment, the glass sheet is arranged on a mold with a frame-like support surface (frame shape).

The impingement of the disk surfaces with the gas stream takes place by introducing a stream of gas into the inner cavity of each blow box, dividing it there and passing it evenly distributed over the nozzle openings onto the disk surfaces.

The gas used to cool the glass is preferably air. The air may be actively cooled to increase the biasing efficiency within the biasing device. Typically, however, air is used which is not specially tempered by active measures.

The disk surfaces are preferably applied to the gas stream over a period of 1 s to 10 s. The vorzuspannende glass is in a preferred embodiment of soda-lime glass, as is customary for windowpanes. However, the glass pane can also contain or consist of other types of glass, such as borosilicate glass or quartz glass. The thickness of the glass sheet is typically from 1 mm to 10 mm, preferably 2 mm to 5 mm. The glass sheet is preferably bent three-dimensionally, as is customary for vehicle windows. A three-dimensional bend is conventionally understood to mean a bend along two (mutually orthogonal) spatial directions, ie a bend along the height dimension of the glass pane and a bend along the width dimension of the glass pane. Bent, prestressed discs are common in the vehicle sector in particular. The glass pane to be pretensioned according to the invention is therefore preferred as Window of a vehicle, particularly preferably a motor vehicle and in particular a passenger car provided.

The closure elements are adapted to the disc shape, so that each nozzle of a blow box preferably has substantially the same distance to the disc surface. During the displacement of the closure elements, the relative arrangement of the nozzles to each other does not change, but the entirety of all the nozzles of a blow box is moved simultaneously on the glass to or from the glass sheet away. The area spanned by the totality of all the nozzle openings, which preferably corresponds substantially to the shape of the disk surface, thus remains constant during the movement of the closure elements and is moved overall toward the glass pane and away from the glass pane.

In an advantageous embodiment, the method according to the invention follows directly on to a bending process in which the glass pane which is planned in the initial state is bent. During the bending process, the glass sheet is heated to softening temperature. The tempering process follows the bending process before the glass sheet has cooled significantly. Thus, the glass pane for tempering does not need to be heated again.

The invention also includes the use of a prestressed with the inventive method glass in locomotion means for traffic on land, in the air or on water, preferably as a window in rail vehicles or motor vehicles, especially as a rear window, side window or roof glass of passenger cars.

In the following the invention will be explained in more detail with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way. In particular, the number of nozzles and channels of the blow boxes are not shown true to reality, but are merely illustrative of the principle.

Show it:

1 is a perspective view of a first embodiment of the blow box according to the invention,

2 shows a cross section perpendicular to the nozzle strips by a blow box according to the invention,

3 shows a cross section along the nozzle strips by a blow box according to the invention,

4 is a perspective view of a nozzle bar,

5 shows a cross section through the nozzle bar of Figure 4,

Fig. 6 is a detail view of a single channel with nozzle bar and a first

Embodiment of the connecting element,

Fig. 7 is a detail view of a single channel with nozzle bar and a second

Embodiment of the connecting element,

Fig. 8 is a detail view of a single channel with nozzle bar in another

Embodiment of the invention,

Fig. 9 is a detail view of a single channel with nozzle bar in another

Embodiment of the invention,

10 shows a cross section through two blow boxes according to the invention as part of a device according to the invention for thermal toughening,

1 1 shows a cross section through a device according to the invention during a

tempering process

12 is a perspective view of another embodiment of the blow box according to the invention,

13 shows a cross section through the blow box of Figure 12 and

14 is a flowchart of an embodiment of the method according to the invention.

FIG. 1 shows a perspective view of an embodiment of the blow box 1 according to the invention for the thermal tempering of glass panes. The blow box 1 has a inner cavity, from which channels 4 extend. The outlet opening of each channel 4 is connected via a connecting element 6 of variable length with a nozzle bar 5, which acts as a closure element and the channel 4 closes. The connecting element 6 are made as tubes from a steel sheet with a material thickness of, for example, 1, 5 mm. Each connecting element 6 is connected telescopically with the associated channel 4: connecting element 6 and the boundary of the channel 4 are thus guided into one another and displaceable relative to one another. The nozzle strips 5 are rigidly connected to one another by means of cross braces 8 and movable together to change the distance between the nozzle strips 5 and the channels 4, the connecting elements 6 of variable length ensuring that the gas flow from the blow box 1 is maintained. In order to set the desired spacing between nozzle strips 5 and channels 4, the blow box 1 has means 7 for moving the nozzle strips 5. These are realized in the form of four servomotors, which are each arranged at a corner of the blow box 1 and drive cylinders which are connected to a nozzle bar 5 or the cross-brace 8. Movement of the cylinders shifts the entirety of the nozzle strips 5 away from or towards the blow box 1.

The nozzle strips 5 are shown for simplicity and clarity for clarity. For biasing curved vehicle windows curved nozzle strips 5 are used in reality, wherein the curved surface, which is spanned by the nozzle openings, the contour of the glass sheet is adjusted. If the glass pane is intended to be positioned relative to the blow box 1, the nozzle bars 5 can be approximated by the servomotors and displaceable cylinders of the glass pane surface, the stationary part of the blow box 1 remaining stationary. To move the relatively light nozzle strips 5 much lower power servomotors are necessary than for movement of the entire blow box 1, as is common in conventional devices. The blow box is therefore cheaper. In addition, the stationary part of the blow box 1 can be used as a universal tool, wherein when converting to a different type of disc only the nozzle strips 5 must be replaced with the connecting elements 6. It is not necessary to produce and store a separate blow box for each type of disc and re-assemble each time it is converted. Again, this is advantageous in terms of the cost and flexibility of the pretensioner. Figure 2 and Figure 3 show cross-sections through a blow box 1 according to the invention similar to that of Figure 1, wherein the sectional surface in Figure 2 is perpendicular to the channels 4 and in Figure 3 along the channels 4. The blow box 1 is of the type, as described for example in DE 3924402 C1 or WO 2016054482 A1. The blow box 1 has an inner cavity 2, to which via a gas feed line 3, an air flow is fed, which is shown in the figures by a gray arrow. The air flow is generated for example by two fans, not shown, connected in series, which are connected via the gas supply line 3 with the blow box 1. By a shutter 12, the air flow can be interrupted without having to turn off the fans.

Opposite the gas inlet 3 close to the cavity 2 channels 4, through which the air flow is divided into a series of partial streams. The channels 4 are formed in the manner of a hollow rib, which in one dimension is substantially as long as the cavity 2 and in the dimension perpendicular thereto have a significantly narrow width, for example about 11 mm. The channels 4 with their elongated cross section are arranged parallel to each other. The illustrated number of channels 4 is not representative and is merely illustrative of the principle of operation.

The cavity 2 is wedge-shaped - along a first dimension, the depth of the cavity 2 in the center of the blow box is greatest and decreases in both directions to the outside. In the second, vertical dimension, the depth remains constant at a given position of the first dimension. The channels 4 are connected to the wedge-shaped cavity 2 along said first dimension. They therefore have a depth profile complementary to the wedge shape of the cavity 2, with the depth in the middle of the channel 4 being lowest and increasing outwards, so that the air outlet of each channel 14 forms into a smooth, plane or curved surface.

Figure 2 and Figure 3 show two cross-sections with an angle of 90 ° to each other. Figure 2 shows the cross section along said second dimension of the blow box 1 transverse to the orientation of the channels 4, so that the individual channels 4 can be seen in section. In the sectional plane, the depth of the cavity 2 is constant. Figure 3 shows the cross section along said first dimension of the blow box 1 along the orientation of the channels 4. Here, the wedge-like depth profile of the cavity 2 can be seen, while in the cutting plane only a single channel 4 is located, the depth profile is also visible.

Each channel 4 is closed at its end opposite the cavity 2 with a nozzle bar 5. Again, the nozzle bars 5 are half straight for simplicity, although they are bent in reality. Through the nozzle bar 1, the air flow is every Channel 4 again divided into further streams, which are each passed through a nozzle 9. In order to change the distance between the nozzle strips 5 of the channels and still maintain the intended air flow, the nozzle strips 5 are connected via connecting elements 6 of variable length with the channels. The connecting elements 6 are formed as tubes made of sheet steel, which are connected telescopically with the channels.

Figure 4 and Figure 5 each show a detail of an embodiment of the nozzle bar 5 according to the invention for a blow box 1 for the thermal tempering of glass panes, again here for the sake of simplicity just shown instead of bent. The nozzle bar 5 is made of aluminum, which can be processed well and has an advantageously low weight. The nozzle bar has, for example, a width of 1 1 mm, wherein the dimensions are adapted to complete the gas channels 4 of an associated blow box 1. As usual in the case of generic nozzle strips, the nozzle strip 5 according to the invention is formed with a series of nozzles 9. Each nozzle 9 is a passage (bore) between two opposite side surfaces of the nozzle bar 5. The nozzles 9 are designed to direct a gas flow from the associated blow box 1 addition, wherein the gas stream via a nozzle inlet 10 enters the nozzle 9 and via a Nozzle opening 1 1 emerges from the nozzle 9. The side surface of the nozzle bar 9 with the nozzle inlets 10 must therefore be facing the blow box 1 in installation position, while the side surface facing away from the blow box with the nozzle openings 1 1.

The individual nozzles 9 have a greatly widened nozzle inlet 10, which is followed by a tapered section. Thereafter, the diameter of the nozzle remains constant at 6 mm to the nozzle opening 1 1.

Figure 6 shows a cross section of a single channel 4 with associated nozzle bar 5, which are telescopically interconnected. For this purpose, the connecting element 6 is designed as a tube and inserted into the channel 4, so that it is displaceable to the channel 4. Alternatively, it is also possible to place the tube on the channel, so that it is arranged outside the channel boundary. The latter variant may even be preferred, because then a cross-sectional constriction in the flow direction, as shown, does not occur and the gas flow is less disturbed.

Figure 7 shows a cross section of a single channel 4 and an associated nozzle bar 5, which are interconnected by means of a bellows as a connecting element 6. The Bellows is connected to the nozzle bar 5 on the one hand and the outlet opening of the channel 4 on the other. The bellows is made of canvas with a material thickness of 0.5 mm. This sufficient gas tightness is achieved to maintain the air flow largely undisturbed.

In the embodiments of Figures 6 and 7, the connecting element 6 is directly / directly attached to the nozzle bar 5.

Figure 8 shows a cross section of a single channel 4 and an associated nozzle bar 5 in a further embodiment. In contrast to Figure 7, the bellows is not mounted as a connecting element 6 directly to the nozzle bar 5. Instead, a gas channel formed as sheets is arranged between the connecting element 6 and the nozzle bar 5. The connecting element 6 is attached to one end of the sheets, while the opposite end of the sheets is attached to the nozzle bar. The gas channel 16 is moved together with the nozzle bar.

Figure 9 shows a cross section of a single channel 4 and an associated nozzle bar 5 in a further embodiment. Again, the bellows is not mounted as a connecting element 6 directly to the nozzle bar 5. Instead, the connecting element 6 is attached to a fastening element 17 for the nozzle bar 5. The fastening element 17 is designed in the manner of a fastening rail, in which the nozzle bar is inserted. For this purpose, the nozzle bar is equipped with a complementary rail element. This rail element may be formed integrally with the nozzle bar or, as shown, be attached as a separate element on the nozzle bar.

FIG. 10 shows an embodiment of the device according to the invention for the thermal tempering of glass panes. The device comprises a first, upper blow box 1.1 and a second, lower blow box 1 .2, which are arranged opposite one another so that the nozzle openings 1 1 of the nozzle strips 5 are directed towards each other. The device further comprises a transport system 13, with which a glass pane I to be prestressed can be transported between the blow boxes 1.1, 1 .2. The glass pane I is mounted horizontally on a frame shape 14, which has a frame-like support surface, on which a peripheral edge region of the glass pane I is placed. The transport system 13 consists for example of rails or a roller system on which the frame mold 14 is movably mounted. The glass pane I is for example a slice of soda lime glass, which serves as a rear window for a passenger car is provided. The glass sheet I has undergone a bending process, wherein it has been brought at a temperature of about 650 ° C, for example by means of gravity bending or press bending in the intended, curved shape. The transport system 13 serves to transport the glass pane I in the still heated state from the bending device to the pretensioning device. There, the two main surfaces are acted upon by the blow boxes 1.1, 1.2 with an air flow in order to cool them down strongly and thus to produce a characteristic profile of tensile and compressive stresses. The thermally toughened glass pane I is then suitable as a so-called single-pane safety glass for use as an automotive rear window. After tempering, the disc is again transported by the transport system 13 from the space between the blow boxes 1 .1, 1.2, whereby the biasing device for biasing the next glass is available. The transport direction of the glass pane I is represented by a gray arrow. FIG. 11 shows a device according to the invention stepwise during the prestressing process according to the invention. The glass pane I to be pretensioned is bent three-dimensionally, as is customary in the field of motor vehicles. Therefore, it is necessary to move the nozzles 9 of the blow boxes 1 .1, 1.2: from a more spaced-apart state, in which the glass sheet I can be moved into the gap, in a state in which the nozzle openings 1 1 as low as possible and in the Identify essentially over the disk surface constant distance to the glass surface. In conventional devices, this movement is accomplished by raising and lowering the entire blow boxes with powerful servomotors. In contrast, in the apparatus according to the invention not the entire blow boxes 1 .1, 1.2 must be moved, but only the nozzle strips 5. First, the nozzle strips 5 of the two blow boxes are widely spaced, so that there is a large gap in which the glass I can be easily retracted (Fig. 1 1 a). If the glass pane I is positioned, the nozzle bars 5 are moved toward the glass pane I (FIG. 11b). All nozzle strips 5 are then arranged at a small distance from the glass surface and the glass sheet I is biased to the air flow. Subsequently, the nozzle strips 5 are again moved away from the glass pane I, so that they can be moved out of the gap. It can be clearly seen in the figure that due to the boiler-like, three-dimensional bending of the glass pane I, it would not have been possible for it to reach its final state To move nozzle strips in the intermediate space, so a movement of the nozzles is required.

FIG. 12 and FIG. 13 each show a detail of a blow box 1 with a simpler design, to which the invention is equally applicable. The stationary part of the blow box 1 here comprises a cover, within which a cavity 2 is formed and to which a gas supply line 3 is connected. Within the stationary part there is no division of the gas flow into channels 4, but the cover has one of the gas supply line 3 opposite openings with a large cross-section. As a movable shutter member, a single nozzle plate 15 is used, which closes the large-area opening and which is provided with a two-dimensional pattern of nozzles 9. The nozzle plate 15 is connected to the stationary part by means of a single bellows as a connecting element 6 of variable length. The nozzle plate 15 is shown here also flat for the sake of simplicity, although in reality nozzle plates are used, which are adapted to the contour of the curved vehicle windows, so are also bent three-dimensionally.

In the illustrated embodiment, the connecting element 6 is attached directly to the nozzle plate 15. However, it is also possible here that 15 further elements are arranged between connection element 6 and nozzle plate, for example a gas channel 16 formed from sheets or a fastening element 17 for the nozzle plate, as shown in FIGS. 8 and 9 in connection with a nozzle strip 5. FIG. 14 shows an embodiment of the method according to the invention for the thermal tempering of glass panes with reference to a flow chart using a device according to FIGS. 10 and 11. LIST OF REFERENCE NUMBERS

(1) blow box

(1 .1) first / upper blow box

(1 .2) second / lower blow box

(2) Cavity of Blaskastens 1, 1.1, 1 .2

(3) Gas supply of the blow box 1, 1.1, 1.2

(4) Channel / nozzle web of the blow box 1, 1 .1, 1.2

(5) nozzle bar (as closure element)

(6) Connecting element of variable length

(7) Means for moving the shutter elements

(8) Crossbar of nozzle bars 5 (9) Nozzle

(10) Nozzle inlet / inlet of the nozzle 9

(1 1) Nozzle opening / outlet opening of nozzle 9

(12) Cover in the gas inlet 3

(13) Transport system for glass panes

(14) Frame shape for glass panes

(15) nozzle plate (as a closure element)

(16) Gas channel between connecting element 6 and closure element

(17) Fastening element between connecting element 6 and closure element

(I) glass pane

Claims

claims

1. blow box (1) for thermally tempering glass sheets, comprising

- A stationary part with a cavity (2 a) and a to the cavity (2) connected to the gas supply line (3) and

at least one closure element (5, 15) having a plurality of nozzles connected to the cavity (2) for impinging a surface of a glass sheet (1) with an air stream,

in which

- The at least one closure element (5, 15) is connected to the stationary part at least via a connecting element (6) of variable length and

- That at least one closure element (5, 15) relative to the stationary part is movable, so that the distance between the closure element and the stationary part is variable, and

- The blow box (1) with means (7) for moving the at least one

Closing element (5, 15) is equipped.

2. blow box (1) according to claim 1, wherein the connecting element (6) is a bellows.

3. blow box (1) according to claim 2, wherein the bellows made of canvas, leather or steel is made with a thickness of 0.5 mm to 3 mm.

4. blow box (1) according to claim 1, wherein the connecting element (6) is designed as a rigid tube and wherein the connecting element (6) and the stationary part are telescopically guided into one another and mutually displaceable.

5. blow box (1) according to claim 4, wherein the tube is made of a sheet with a material thickness of 0.5 mm to 3 mm.

6. blow box (1) according to one of claims 1 to 5, wherein the connecting element (6) directly or indirectly on the closure element (5, 15) is mounted.

A blow box (1) according to any one of claims 1 to 6, comprising a single closure element which is a nozzle plate (15) and is connected to the stationary part by means of a single connecting element (6).

8. blow box (1) according to one of claims 1 to 6, which has a plurality of connected to the cavity (2) channels (4) which are each the cavity (2) opposite to a nozzle bar (5) closed as a closure element, wherein each nozzle bar (5) with its associated channel (4) via a connecting element (6) of variable length is connected.

9. blow box (1) according to claim 8, wherein the nozzle strips (5) are rigidly connected together so that they are movable together.

10. An apparatus for thermally tempering glass sheets, comprising

- A first blow box (1.1) according to one of claims 1 to 9 and a second blow box (1.2) according to one of claims 1 to 9, which are arranged opposite to each other, so that the closure elements (5, 15) of the first blow box (1.1) and the second blow box (1.2) face each other; and

- Means for moving a glass sheet (I) in a space between the first blow box (1 .1) and the second blow box (1 .2).

1 1. Apparatus according to claim 10, wherein the means for moving the glass sheet (I) comprises a frame mold (14) on which the glass sheet (I) is disposed, and a transport system (13) for moving the frame mold (14).

12. A method for thermally tempering a glass sheet, wherein

(A) a heated glass pane (I) having two major surfaces and a peripheral side edge, between a first blow box (1 .1) according to one of claims 1 to 9 and a second blow box (1 .2) according to one of

Claims 1 to 9 is arranged so that the two main surfaces can be acted upon with a gas stream;

(B) the closure elements (5, 15) of the two blow boxes (1 .1, 1 .2) are approximated to the glass sheet (I) and

(c) the two main surfaces of the glass pane (I) by means of the two blow boxes (1.1,

1 .2) are subjected to a gas flow, so that the glass sheet (I) is cooled.

13. The method according to claim 12, wherein in step (b) the stationary parts of the blow boxes (1 .1, 1 .2) remain stationary.

14. The method of claim 12 or 13, wherein the glass sheet (I) is bent along two spatial directions.

15. Use of a prestressed by the method according to any one of claims 12 to 14 glass sheet (I) in means of transport for traffic on the

Land, in the air or on water, preferably as a window in rail vehicles or motor vehicles, especially as a rear window, side window or roof glass of passenger cars.