DE102008036513A1 - Device for transporting flat glass strips, comprises a roller arranged in the area of a lower side of the flat glass strips, and a levitation unit arranged in the area of the lower side of the flat glass strips and next to the roller - Google Patents

Abstract

The device comprises a roller arranged in the area of a lower side of the flat glass strips, and a levitation unit (1) arranged in the area of the lower side of the flat glass strips and next to the roller. The roller has a deflection (D(R)) along its longitudinal axis and the levitation unit has a deflection (D(LM)) along its longitudinal axis, where the D(R) and D(LM) deviate less than +/-20% from each other. The roller and/or the levitation unit are interchangeable in the running operation. Independent claims are included for: (1) an apparatus for producing a flat glass; (2) a method for transporting flat glass strips; and (3) a method for producing a flat glass.

Description

The The invention relates to an apparatus and a method for transportation a flat glass band. The device is provided with at least one, arranged in the region of the underside of the flat glass ribbon roll and at least one, in the region of the underside of the flat glass band and provided next to the roll arranged levitation unit. At the Method for transporting the flat glass ribbon is the flat glass ribbon by means of at least one, in the region of the underside of the flat glass ribbon arranged roll and at least one, in the region of the bottom the flat glass ribbon and adjacent to the roll arranged levitation unit transported and supported. Furthermore, the invention relates an apparatus and a method for the production of flat glass. The device has, in addition to means for hot forming a glass melt to obtain a flat glass ribbon the inventive Device for transporting the flat glass ribbon. In the process For the production of flat glass, a glass melt becomes a flat glass ribbon hot-formed and the flat glass ribbon by means of at least one, arranged in the region of the underside of the flat glass ribbon roll and at least one, in the region of the underside of the flat glass band and transported adjacent to the roller arranged levitation unit and supported.

In It is common in the flat glass industry to use endless flat glass bands following the hot forming of a glass melt (e.g. B. by means of floating, pulling or rolling) on roller fields to transport and support and of shaping to move away and thereby defined cooling or annealing and after cooling or tempering in flat glass panes to separate. The roles and their recording are designed to that the roles can be exchanged during operation to For example, subject them to cleaning or new ones Replace roles. Depending on the configuration of such a transport device, the usually part of a so-called roller cooling furnace (RO) is, are suitable for quick replacement tools, z. B. role change recordings, ready.

The Rollers handle transport and support of the glass band. It is inevitable that the roles with contact the glass ribbon. Depending in particular temperature and / or Print of the glass ribbon on the roll, type of glass composition and material of the roll, this contact can cause surface damage and defects on the transported and supported glass ribbon to lead.

It is known that such contact and resulting Surface defects on the glass ribbon due to the use of supporting gas cushions - the flat glass ribbon floats, d. H. levitated on a gas cushion -, be avoided can.

So are in Scripture US 3,300,291 Possibilities described to introduce levitation units in addition to rollers in the roller cooling furnace to support the glass ribbon.

In Scripture DE 101 41 498 A1 a roller table for carrying and conveying a hot glass ribbon is described, with a plurality of rollers which are arranged parallel to each other and perpendicular to the conveying direction of the glass strand, and which are displaceable about their own longitudinal axis in circulation; at least some of the rollers are sleeves whose sheath is permeable to gas on at least part of their surfaces and has a gas connection to at least one of their faces.

Furthermore, a device for supporting a glass ribbon with at least one arranged in the region of the underside of the glass ribbon roll of the font EP 1 312 585 A2 known. This device for supporting a glass band with at least one arranged in the region of the underside of the glass ribbon roller is characterized in that the roller is associated with at least one support device that by means of an actuator selectively the roller or the support device can be brought into contact with the glass ribbon bottom, wherein the support device is at least partially over a gas cushion in contact with the glass band underside.

Methods and devices for transporting, supporting and cooling or tempering flat glass or for producing flat glass are furthermore known, for example, from the following documents: EP 1 491 509 A1 . US 6,204,483 B1 . WO 2006/097155 A1 . DE 103 07 661 A1 . DE 10 2005 051 879 B3 ,

All Previously known devices and methods are each for certain manufacturing conditions adapted solutions, particularly in the event of a change in the production, Transport, support and / or tempering conditions as inflexible and often with changes in manufacturing conditions lead to an increase in surface defects on the glass ribbon, or unnecessary costs z. B. by hot gas consumption cause.

It is therefore an object of the invention to find an apparatus and a method for transporting a flat glass ribbon, which overcomes the disadvantages of the known prior art, and according to the respective manufacturing conditions can be used and changed quickly and flexibly. In particular, production stoppages are to be prevented and the quality and yield of the respective flat glass to be produced maintained or improved. It is another object of the invention to find an apparatus and a method for producing flat glass, which advantageously integrates the transport device and the transport method.

According to claim 1, this object is achieved by a device for transporting a flat glass strip with at least one disposed in the region of the underside of the flat glass ribbon roll and at least one, in the region of the underside of the flat glass ribbon and arranged next to the roll levitation unit. The device is characterized in that the roller along its longitudinal axis has a deflection D _R and the levitation unit along its longitudinal axis has a deflection D _LM , wherein D _R and D _LM less than +/- 20%, preferably less than +/- 10% , differ from each other.

wobei RA der Abstand von Rolle und Levitationseinheit, gemessen von deren Mitte,
<SH> die mittlere Schwebehöhe über der Levitationseinheit und
MB die Modulbreite der Levitationseinheit ist.It has proved to be particularly advantageous if the following equation applies to the deviation of the deflections:

where RA is the distance between the roller and the levitation unit, measured from the center,
<SH> the mean flying height above the levitation unit and
MB is the module width of the levitation unit.

Especially to avoid production stoppages or to switch to production changes or the change in production conditions react quickly to be able to, it is beneficial if the respective role and / or the respective levitation unit exchangeable during operation are.

advantageously, is the role and the levitation unit so designed and dimensioned, that the role can be replaced by the levitation unit and vice versa.

According to claim 4, the object is achieved by a device for producing flat glass, which is characterized in that the device comprises means for hot forming a molten glass to obtain a flat glass ribbon, a device for transporting the flat glass ribbon according to at least one of claims 1 to 3. Thus, the device for transporting a flat glass strip with at least one disposed in the region of the underside of the flat glass ribbon roll and at least one, in the region of the underside of the flat glass ribbon and disposed next to the roll levitation unit. The device is characterized in that the roller along its longitudinal axis has a deflection D _R and the levitation unit along its longitudinal axis has a deflection D _LM , wherein D _R and D _LM less than +/- 20%, preferably less than +/- 10% , differ from each other.

wobei RA der Abstand von Rolle und Levitationseinheit, gemessen von deren Mitten, <SH> die mittlere Schwebehöhe über der Levitationseinheit und M8 die Modulbreite der Levitationseinheit ist.Furthermore, it is preferable for the apparatus for transporting flat glass at the following for the deviation of the deflections equation:

where RA is the distance of roll and levitation unit, measured from their centers, <SH> is the mean flying height above the levitation unit and M8 is the module width of the levitation unit.

Especially to avoid production downtime or to move quickly to production changes Being able to react, it is beneficial if the respective Role and / or the respective levitation unit during operation are interchangeable.

Furthermore, the object is achieved according to claim 5 by a method for transporting a flat glass ribbon, wherein the flat glass ribbon is transported by means of at least one disposed in the region of the underside of the flat glass ribbon roll and at least one, in the region of the underside of the flat glass ribbon and adjacent to the roll arranged levitation unit. The flat glass ribbon is thereby transported along the longitudinal axis thereof at a deflection D _{R of} the roll and along its longitudinal axis in the case of a deflection D _{LM of} the levitation unit, wherein D _R and D _{LM are} less than +/- 20%, preferably less than +/- 10%, differ from each other.

According to claim 6, the object is achieved by a method for producing flat glass, wherein a flat glass sheet is hot formed from a molten glass and the flat glass ribbon is transported according to the method of claim 5. The flat glass ribbon is thereby transported along the longitudinal axis thereof at a deflection D _{R of} the roll and along its longitudinal axis in the case of a deflection D _{LM of} the levitation unit, wherein D _R and D _{LM are} less than +/- 20%, preferably less than +/- 10%, differ from each other.

• – Querschnittsfläche kleiner als die Rollenquerschnittsfläche
• – Länge größer als die Breite des Kühlofens bzw. Rollenkühlofens
• – Aufbringen von Schutzschichten auf das Glasband über Art und Zusammensetzung des Levitationsgases, z. B. feuchte oder trockene Gasphase
• – Gasmenge zur Levitation über den gemessenen Gasmengenfluss aktiv regelbar

Furthermore, the following technical features of the levitation unit have proved advantageous:

• - Cross-sectional area smaller than the roller cross-sectional area
• - Length greater than the width of the cooling furnace or roller cooling furnace
• - Applying protective layers on the glass ribbon on the nature and composition of the levitation gas, z. As humid or dry gas phase
• - Gas volume for levitation via the measured gas flow rate can be actively controlled

advantageously, The levitation unit will be designed to work in progress Operation single roles of roller cooling furnace available can replace. For this, the levitation unit must have properties, which will now be described in detail.

The Levitation unit is intended as the conventional rollers outside the device (for example, the roller cooling) recorded and kept. All supply devices, especially for the supply of levitation required gas or gases, are preferably to the Attached end faces outside the device.

The Levitation unit is preferably in its cross-sectional area not larger than the cross-sectional area the roles to be replaced. Also, the cross-sectional shape of the levitation unit be chosen so that they pass through the side openings the device according to claim 1 is insertable. In one embodiment, therefore, the reel body a role to be replaced a starting body for to be the levitation unit to be produced.

Dabei ist RA der Abstand von Rolle und Levitationseinheit, gemessen von deren Mitten,
<SH> die mittlere Schwebehöhe über der Levitationseinheit und
MB die für die Levitation relevante Modulbreite der Levitationseinheit ist, d. h. die Breite der Fläche, in die Auslässe für das Levitationsgas eingebracht sind (s. 5).Depending on the design of the gas outlets required for the levitation surfaces and the amount of gas used for levitation, there is a fly height (SH) of the glass ribbon on the levitation unit in the range of a few tenths of a millimeter to a few millimeters. With economically acceptable amounts of gas, the flying height is in the range of a few tenths of a millimeter. Therefore, in the case where the roller and the levitation unit are used in parallel, the levitation unit can be designed so that its deflection D _LM under load of the glass band approaches the deflection D _{R of} the rollers under load of the glass ribbon. In particular, the difference in the deflections D _R and D _{LM should be} sufficiently small at each point along the longitudinal axis of the roller and levitation unit. In particular, it has been found that the glass ribbon levitates well and there are no contact points on the glass ribbon, if the following condition is met:

Where RA is the distance between the role and the levitation unit, measured from their centers,
<SH> the mean flying height above the levitation unit and
MB is the relevant for the levitation module width of the levitation unit, ie the width of the surface are placed in the outlets for the levitation gas (s. 5 ).

The mean flying height <SH> depends on the amount of gas dependent. Economically meaningful flying heights are flying heights of a maximum of 2 mm, preferably less than / equal 1 mm, more preferably between 0.05 and 0.8 mm.

The Fly height SH can be determined by means of feeler gauges be pushed between glass ribbon and levitation unit. These have a thickness of 0.1 to 1 mm in 0.1 mm increments. The Fly height results from the teaching, the largest possible Thickness, which is still pushed between glass ribbon and levitation module can be. The mean flying height <SH> yields extending from the mean of a given length along the longitudinal axis on both sides of the levitation module determined values.

are adjacent to two levitation units, the relationship must also be for the difference of the deflection of the levitation units is respected become.

In order for the glass ribbon to "snuggle up" to the levitation unit, the following condition should preferably be adhered to: D glass tape > D LM

To determine the deflection of the glass ribbon D _{glass ribbon} , a piece of this tape is placed with the full width on two line pads, which have a distance that is only slightly smaller than the width of the glass ribbon (including braids). The deflection now results from the height difference of the pads and the middle of the glass band.

To determine the deflection of the rollers D _R and the Levieinheit D _LM these are placed on two supports whose distance is only slightly smaller than the length of the roller or the levitation unit along its longitudinal axis. The deflection results from the height difference of the supports and the center of the roller or the levitation unit along its longitudinal axis.

The deflections D _R and D _LM depend on the weight of the roller or the levitation unit, the modulus of elasticity (modulus of elasticity) of the material, the cross-sectional shape (area moment of inertia), the spanned length and the external load through the glass band. Since the load of the glass ribbon and the spanned length is specified, the area moment of inertia (cross-sectional shape) as well as the dead weight and modulus of elasticity (material characteristic value) are adjustable sizes.

In a particular embodiment can be the Actively adjust deflection via suitable means. So can by choosing a material with a suitable coefficient of linear expansion and suitably positioned heat sources or heat sinks the deflection will be changed. So z. B. a heat source on the bottom of the levitation unit to an increase in deflection, a heat source the top of the levitation unit to a decrease in the deflection. Also other ways to influence the deflection are conceivable: compressive or tensile stresses along and / or parallel the longitudinal axis or forces in the direction of gravity, or opposite.

Ideally the levitation unit is designed so that it over a wide range of load is similar in the Deflection behaves like the adjacent rolls

Should individual roles are replaced by levitation units, it is It is advantageous to provide means for exact level adaptation of the levitation units. This includes among other things a sufficiently accurate height adjustment Levitation units, a twisting mechanism for precise alignment the flat surface and means for measuring the position of Levitation units relative to the glass ribbon as well as relative to the other roles.

The Gas quantity of the levitation unit can preferably via a flow sensor and adjusting devices (z. B. over flaps and / or the fan speed) active be regulated so that with minimal gas use a sufficiently high Flying height is achieved.

The Levitation gas can be tempered before it enters the levitation unit is introduced. It can depending on the application to a lower, higher or at the same temperature as for example, the atmospheric temperature in the device, z. B. the reel cooling furnace, are brought.

The Levitation units described here may u. a. advantageous in the Drossbox of a Glasfloatbades, in the cooling track one Glasfloatbades and in the cooling path of a rolling mill for Production of flat glass and / or glass ceramic can be used.

Embodiment 1

In a roller cooling furnace on a float bath for the production of 4 mm thick flat glass rolls with 150 mm diameter and with a length of 4.8 m are used. These are made of solid quartz material and therefore have a resulting elastic deflection D _R of 2.2 mm under load. In areas where bottom defects on the flat glass strip are produced by roller contact, the rollers are replaced by levitation units, which also consist of fused silica. These also have the length of 4.8 m and a diameter of 150 mm, but are hollow inside (inner diameter about 80 mm) and have a flat surface parallel to the axis (s. 5 ). This area has a width of 100 mm and two rows of holes at a distance of 50 mm. The individual holes have a diameter of 2 mm and a distance of 50 mm in the middle third of the levitation unit and 75 mm on the sides. The levitation unit is supplied with air at a pres- sure of 50 mbar and a gas temperature of 400 ° C. The levitation unit has a resulting deflection D _LM of 2.1 mm under load. The installation of the levitation units significantly reduces the underside defects on the glass ribbon.

Comparative Example 2:

In a roller cooling furnace on a float bath for the production of 8 mm thick flat glass rolls with a diameter of 200 mm and a length of 4.8 m are used. These are made of solid quartz material and therefore have an elastic deflection under load D _R of 0.63 mm. In areas where bottom defects are caused by roller contact, the rollers are replaced by levitation units, which consist of a temperature-resistant ceramic. These also have the length of 4.8 m and a substantially rectangular cross-section, which can be described by a circle with a diameter of 150 mm. And are designed inside hollow (wall thickness about 10 mm) and have a glass band facing flat surface parallel to the axis. This area has a width of 100 mm and two rows of holes at a distance of 50 mm. The individual holes have a diameter of 2 mm and a distance of 50 mm in the middle third of the levitation unit and 75 mm on the sides. The levitation unit is supplied with air at a pres- sure of 50 mbar and a gas temperature of 400 ° C. The levitation unit has a deflection D _LM of 1.1 mm under load. After installation, there are occasional touches between the glass ribbon and the levitation unit and thus surface defects on the glass ribbon and the resulting flat glass.

In the following, the invention is based on the 1 to 5 explained in more detail.

1 shows a levitation unit 1 with the deflection D _LM when resting on support points 2 holding the levitation unit 1 in the device according to the invention for transporting a Flat glass band serve. The levitation unit 1 So is part of the device for transporting a flat glass strip or part of a device for producing flat glass, wherein the deflection D _{LM of} the levitation unit 1 less than +/- 20% from the deflection D _{R of} an adjacent roll of such a device for transporting the flat glass ribbon.

2 shows schematically the supply of the levitation unit 1 with gas. This designates 3 a device for tempering the gas and 4 a gas supply.

3 shows the measurement of the deflection D of the glass ribbon 5 with circulation on support points 6 ,

4 shows the cross section through a conventional role 7 made of solid material.

5 shows the cross section through a levitation unit 1 to exchange against a roll and the definition of module width (MB). The levitation unit 1 has a coat 8th and a cavity for gas supply. The gas flows through openings 9 and supports that over the openings 9 located glass band.

1

Levitationseinheit

2

contact points Levitationseinheit

3

device for temperature control of the gas

4

gas supply

5

glass tape

6

contact points glass tape

7

role

8th

Levitationseinheit

9

drilling as a gas outlet

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 3,300,291 [0005]
• - DE 10141498 A1 [0006]
• - EP 1312585 A2 [0007]
• - EP 1491509 A1 [0008]
• - US 6204483 B1 [0008]
• WO 2006/097155 A1 [0008]
• - DE 10307661 A1 [0008]
• DE 102005051879 B3 [0008]

Claims (6)

Device for transporting a flat glass band with at least one arranged in the region of the underside of the flat glass ribbon and at least one, in the region of the underside of the flat glass ribbon and next to the roller arranged levitation unit, characterized in that the roller along the longitudinal axis of a deflection D _R and the levitation unit along its longitudinal axis has a deflection D _LM , wherein D _R and D _LM differ less than +/- 20% from each other. Apparatus according to claim 1, characterized in that the following equation applies to the deviation of the deflections:

where RA is the distance of roller and levitation unit, measured from their centers, <SH> the mean flying height above the levitation unit and MB is the module width of the levitation unit. Device according to at least one of the preceding Claims, characterized in that the role and / or the levitation unit are interchangeable during operation. Apparatus for the production of flat glass, characterized in that the device is provided in addition to means for hot forming a glass melt to obtain a flat glass ribbon, a device for Transport of the flat glass ribbon according to at least one of claims 1 to 3 Method for transporting a flat glass strip, wherein the flat glass strip is transported by means of at least one roller arranged in the region of the underside of the flat glass strip and at least one levitation unit arranged adjacent to the roller in the region of the underside of the flat glass strip, characterized in that the flat glass strip is deflected at a deflection D _{R of} the roller is transported along its longitudinal axis and at a deflection D _{LM of} the levitation unit along its longitudinal axis, wherein D _R and D _LM differ less than +/- 20% from each other. Process for the production of flat glass, wherein a glass melt, a flat glass ribbon is heat formed, characterized in that the flat glass ribbon according to the Method according to claim 5 is transported.