WO2019043334A1

WO2019043334A1 - Improved heat treatment device

Info

Publication number: WO2019043334A1
Application number: PCT/FR2018/052118
Authority: WO
Inventors: Cécile OZANAM; Emmanuel Mimoun; Johann SKOLSKI; Lorenzo CANOVA
Original assignee: Saint-Gobain Glass France
Priority date: 2017-08-30
Filing date: 2018-08-29
Publication date: 2019-03-07
Also published as: CN111032590A; KR20200046056A; EP3676230A1; FR3070387A1

Abstract

The present invention concerns a device (1) for heat treatment of a coating (R) deposited on a substrate (S), comprising heating means (10) opposite which the substrate can pass, said heating means (10) being designed to heat the coating on the first surface of the glass substrate, characterised in that said heat treatment device also comprises a pre-heating means (10') designed to heat the coating of said substrate passing upstream of the heating zone.

Description

IMPROVED THERMAL TREATMENT DEVICE

The present invention relates to the field of thin-film heat treatment on glass substrates.

PRIOR ART

It is known to carry out a local and rapid annealing (flash heating) of coatings deposited on flat substrates. For this, the substrate is passed with the coating to be annealed under a heating means such as a flash lamp or a plasma torch, or a laser line, arranged above the substrate carrying the coating.

Rapid annealing is used to heat thin coatings at high temperatures, on the order of several hundred degrees, while preserving the underlying substrate. The scroll speeds are of course preferably the highest possible, preferably at least several meters per minute.

For example, in a laser line used, it comprises at least one laser generator providing a laser beam. This laser beam is focused in order to locally increase the thermal power supplied by the laser generator.

This annealing process whether it is laser or flash lamp or other has the disadvantage of being energy-hungry, this energy greed increasing with the increase in the capabilities of the line especially in terms of processing speed. Such energy greed involves high costs.

SUMMARY OF THE INVENTION The present invention therefore proposes to solve these disadvantages by providing a thermal treatment device for rapid annealing which is more energy efficient and less expensive. For this purpose, the invention relates to a device for heat treatment of a coating deposited on a substrate comprising heating means against which the substrate can pass, said heating means arranged to heat an area of the coating on the first face of the glass substrate, characterized in that said heat treatment device further comprises a preheating means arranged to heat the coating of said moving substrate, upstream of the heating zone.

This invention has the advantage of preheating the coating which reduces costs since it becomes possible to use heating means having a lower power or use less efficient heating means. This use also increases the scroll speed since the coating is preheated.

According to one example, the heating means are arranged to raise the temperature of the coating in a range of 300 to 700 ° C, in particular from 500 to 650 ° C for a period of time of not more than 1 ms and the preheating means are arranged to raise the temperature of the coating by at most one-third of the temperature reached by the coating via heating means for a period of time of not more than 50 ms.

According to an example, the device further comprises a recycling device for using the unabsorbed portion of the energy supplied by the heating means to serve as preheating means.

In one example, the heating means comprise a laser system comprising at least one laser generator.

In one example, the laser system is positioned to be angularly offset from the perpendicular to the glass substrate.

In one example, the heating means comprise a plurality of flash lamps.

In one example, the recycling device is a reflective element arranged to reflect the portion of the light beam that is not absorbed by the substrate and to direct it onto the coating of said moving substrate in order to act as a preheating means.

This example advantageously allows to have only one device to operate the heating and preheating to reduce costs at most. This also allows to have a simpler heat treatment device because there is only the heating means to set.

In one example, said reflective element is a mirror arranged facing the face opposite to the face of said substrate carrying the coating.

In one example, said reflective element is a flat mirror extending parallel to the plane of the substrate.

In one example, said reflective element is a curved mirror.

In one example, said reflective element is movable in at least one degree of freedom.

In one example, the degree of freedom is a translation in a plane perpendicular to the plane of the substrate.

In one example, the degree of freedom is a rotation with respect to an axis perpendicular to the direction of travel.

In one example, said reflective element is arranged to reflect a beam in two distinct directions for orienting the unabsorbed beam on either side of the focusing point.

According to one example, said reflective element is a mirror comprising two sections forming between them an angle, the faces of the outer corner being reflective.

In one example, said reflective element comprises a triangular section cylinder block having two parallel slice faces and three side faces, two adjacent side faces being reflective.

In one example, said reflective element is a reflective layer deposited on the face of said substrate opposite the face carrying the coating.

According to one example, the substrate extends in a first dimension and a second dimension orthogonal to the first dimension, said substrate traveling in a collinear direction to the larger of the two dimensions, and in that the laser beam extending in a direction orthogonal to the direction of scrolling.

In one example, the preheating zone and the heating zone are disjoint.

According to one example, said substrate extends in a first direction which is its length and a second direction which is its width and which is orthogonal to the first direction, said substrate traveling along its length, the preheating zone and the heating zone extending over the entire width of the substrate.

DESCRIPTION OF THE FIGURES

Other particularities and advantages will emerge clearly from the description which is given hereinafter, by way of indication and in no way limiting, with reference to the appended drawings, in which:

FIG. 1 is a schematic representation of the heat treatment device according to the invention;

FIG. 2 is a schematic representation of the heat treatment device using laser technology according to a first embodiment of the invention;

-the figs. 3 and 4 are diagrammatic representations of a variant of the heat treatment device according to the first embodiment of the invention;

FIG. 5 is a schematic representation of the heat treatment device according to a second embodiment of the invention;

FIG. 6 is a schematic representation of the heat treatment device using flash lamp technology according to a first embodiment of the invention;

DETAILED DESCRIPTION OF THE INVENTION

In Figure 1 is shown the heat treatment device 1 of a substrate S according to the invention. The treated substrate S is, for example, a wide-width glass substrate, such as a "jumbo" flat glass sheet (6 mx 3.21 m) emerging from the float processes. Of course, the heat treatment device 1 of a substrate S according to the invention is adaptable to substrates of different sizes. This heat treatment device 1 comprises conveying means 2 for transporting the substrates S, for example glassmakers. Such conveying means 2 may be in the form of two parallel rails on which a frame provided with supports for the substrate S is arranged. It can also be provided that the conveying means 2 are in the form of two parallel rails on which wheels are mounted allowing the substrate to be movable. Some wheels are then connected to a motor to allow the scrolling of the substrate.

For a glass substrate in the form of a "jumbo" flat glass sheet (6 mx 3.21 m), it will be provided that the conveying takes place in a first direction extending along the greatest of two dimensions of the leaves. In the case of a "jumbo" size sheet (6 mx 3.21 m), it will be defined that the sheet has a length of 6 m and a width of 3.21 m and that the conveying means 2 allow said glass sheet to move along its length, that is to say in the direction of its length.

The heat treatment device 1 further comprises heating means 10. These heating means 10 may be in various forms and are advantageously arranged to supply energy E for raising the temperature of the coating, in a heating zone, in a heating zone. an interval of 300 to 700 ° C, in particular 500 to 650 ° C for a period of time of not more than 1 ms. These heating means 10 comprise, for example, a flash lamp system 10a comprising at least one flash lamp or a plasma system comprising at least one plasma torch or a laser system 10b comprising one or more laser generators L for supplying said energy. The heating zone extends over the entire width of the substrate.

In the case of a laser system 10b visible in FIG. 2, each laser generator L can use solid-state laser or diode laser technology or disk laser that is the perfect combination of a solid-state laser. with a diode laser allowing beam quality and superior performance. These heating means 10 make it possible to anneal a coating R or a layer deposited on the substrate S. This substrate S comprises a first face and a second face, the first face is the face supporting the layer / coating R to anneal. The second face is the face in contact with the conveying means. The substrate S is preferably a substrate transparent to the wavelength of the laser.

The laser generator L provides a beam F passing through an optical element to obtain a beam F in the form of a line having a length, for example and without limitation, ranging from 10 to 50cm and a width less than Ι ΟΟμιτι.

In the case of a plurality of laser generators L, the latter are arranged next to each other in order to add up to form a single line of great length. In this case and in order to be able to adjust the alignment of these different beams and thus obtain a laser line as homogeneous as possible, an alignment system (not shown) is provided.

In the case of a flashlamp system 10a shown in Figure 6, the system 10 includes a plurality of LD discharge lamps providing a broad spectrum pulsed light to provide power. Several tubes are put side by side to form an area irradiated by a flash of several tens of centimeters. To bring the light back to the area to be irradiated, a reflective cover C is arranged at the rear of the tubes and on the sides to reflect light forward. This reflective cover C is advantageously designed to reduce the light without it diverge too much. The light source has a duration of less than 1 ms. Compared to a laser system, this flash lamp technology allows a larger area to be treated due to the arrangement of the tubes.

Cleverly, the invention proposes to provide a preheating means 10 'of the coating R upstream of the heating means 10. These preheating means 10' are arranged to raise the temperature of the coating R, in a preheating zone, about 100 ° C and at most one third of the temperature reached by the coating R via heating means 10 for a period of time between 1 ms and at most 50 ms. The preheating zone is separate from the heating zone, ie there is a gap between these two zones which is not not heated or preheated. This preheating zone extends over the entire width of the substrate.

These preheating means 10 'may for example be a laser line or a flash lamp line or a resistive plate of lesser power than the heating means and arranged upstream of the heating means 10, preferably in a contiguous manner. that is to say that the spacing between the preheating means 10 'and the heating means 10 is as small as possible in order to avoid heat losses.

It may therefore be, for example and without limitation, a heat treatment device 1 which comprises a resistive plate as a preheating means 10 'and a flash lamp system as a heating means 10 or which comprises a laser system as a means of preheating 10 'and a flash lamp system as a heating means 10 or alternatively comprising a flash lamp system as a preheating means 10' and a laser system as a heating means 10.

Even more cleverly, the present invention proposes to use the existing heating means 10 to operate this preheating. In the case of a heat treatment operated by laser, it is cleverly provided to use the laser beam F of the laser generator L to carry out said additional heat treatment step on the substrate S as shown in FIG. 2.

According to a first embodiment, the heat treatment device 1 further comprises recycling means RC to allow the preheating of the glass substrate. For this, the heat treatment device 1 comprises a reflector element 20. Here, this reflector element 20 is a mirror M. This mirror M is arranged under the substrate S. In this first embodiment, it will be taken for example means heater 10 comprising at least one laser generator L, this example not being limiting and can be applied for a flash lamp or plasma torch or any other heating means 10. This arrangement allows to act on the part of the non-laser beam absorbed by the coating R and the substrate S, the latter being transparent to the wavelength used for the heating means 10. This unabsorbed laser beam f is defocused, the focusing taking place at level of the coating R to anneal. The mirror M is then positioned so that the unabsorbed laser beam f is reflected. This reflection is designed so that the reflected unabsorbed beam f is reflected towards the glass substrate S upstream of the focusing point of the laser beam F. Such a configuration makes it possible to heat the coating deposited on the glass substrate S before passing through the beam localized laser. This preheating thus makes it possible either to reduce the power of the laser since the power is better used, or to increase the conveying speed.

To avoid damaging the laser generator L, it will be installed so that the laser beam F is not perpendicular to the glass substrate. This arrangement advantageously makes it possible to use a mirror M and place it parallel to the plane of the glass substrate S. This arrangement makes it possible more particularly to use a simple flat mirror M for reflecting the unabsorbed laser beam f.

However, the mirror M may be inclined relative to the plane of the glass substrate S. In addition, the mirror M is not limited to a flat mirror, it may be convex or concave shape curve.

In order for the unabsorbed laser beam to be reflected towards the glass substrate S upstream of the focusing point, the laser generator L will be positioned so as to be offset angularly with respect to the perpendicular to the glass substrate. The angle of incidence of the laser on the glass substrate S will be between 5 and 15 °, preferably between 7 and 10 °.

The preheating is done because the reflected defocused beam f has a pfd significantly lower compared to the focused beam F. This reduced pfd makes it impossible to anneal the coating R deposited on the glass substrate S but is sufficient to allow the preheating of the coating of said substrate S.

This pfd can be modified. Indeed, the reflected beam f is defocused, that is to say that the beam surface is not constant. Consequently, by modifying the distance D between the mirror M and the glass substrate S, the area of the laser beam reflected at the level of said substrate and therefore the pfd varies. By increasing the distance D between the mirror M and the second face of the glass substrate S, that is to say in placing the mirror M in translation in a direction perpendicular to its plane, the width La of the reflected beam which preheats the glass substrate S is increased and the distance d between the preheated zone and the focusing point is also increased. Similarly, it is possible to change the inclination of the plane of the mirror M to change the position of the preheating. By changing the inclination of the mirror M, the distance between the mirror M and the preheated coating is changed so that it is possible for the power to vary.

In the case of a flash lamp system, the reflector element 20 can also be used to reflect unused light during processing and preheat. In this case, the reflector element 20, ie the mirror, has a larger width to accommodate the large irradiation zone. In addition, the distance between said reflector element 20 and the glass substrate S on which the coating is deposited is very small to minimize the divergence.

In a variant of this first embodiment, the means to allow preheating also allow post-heating to obtain a slow cooling of the treated coating. For this, the reflector element 20 is arranged to be able to reflect the unabsorbed beam f in two different directions as can be seen in FIG.

In a first embodiment, the reflector element 20 of this second embodiment is a bent mirror M '. Such a mirror M 'comprises two sections m forming, between them, an angle. The faces of the external angle (the larger of the two angles) are reflective while the faces of the internal angle allow the presence of support means of the reflector element 20.

In a second embodiment visible in FIG. 4, the reflector element 20 is a mirror M "in the form of a cylinder block 200 of triangular section .This mirror M" comprises two parallel slice faces 201 and three faces of side 202. Two adjacent side faces are reflective.

This positioning of the reflector element 20 advantageously makes it possible to split the unabsorbed beam f in two. A first split portion is directed upstream of the focus point while the second split portion is directed downstream of the focus point. If the first part split up and directed upstream allows preheating of the glass substrate S, the second portion split and directed downstream of the focusing point improves the cooling. Indeed, this ensures a lower temperature drop after the heat treatment.

The reflector element 20 may be designed and positioned to split the unabsorbed beam equitably or to unequally split it to favor the upstream or downstream portion of the focusing point. To modify the split ratio of the unabsorbed beam f by the reflector element 20, the position of the vertex is changed. To control the pfd, the inclination angles of the two reflective sections are used and are modified. The angles of inclination can have different values and be modified independently.

The heat treatment device 1 further comprises a beam shield BD. This beam shield BD is arranged on the path of the reflected unabsorbed beam f. More particularly, this beam shield BD is arranged above the glass substrate S. This arrangement allows the beam shield BD to be the element which stops the propagation of the reflected unabsorbed beam f. This shield BD is advantageously made of a heat-resistant material such as a ceramic or a metal with a high melting point and / or can be cooled. In the case of an unabsorbed beam split in two, two BD beam shields may be present.

In a second embodiment as shown in FIG. 5, the reflector element 20 is a reflective layer 21. This reflecting layer 21 is arranged on the glass substrate S at its second face, that is to say the face opposite to the face carrying the coating R. This reflective layer 21, to be effective, has a reflectivity of at least 70%, preferably at least 80%.

Thus, this reflective layer 21 reflects the unabsorbed beam f. This reflection is similar to that of the mirror M described in the first embodiment, that is to say that the unabsorbed beam f is reflected upstream of the focusing point. In a non-limiting example of configuration, the glass substrate is 4mm thick, the laser has a power of 433W and a width of δθμιτι, the reflectivity of the reflective layer is 80% and the angle of incidence of the laser on the glass substrate is 7 °. Thus, in this case, the reflected unabsorbed beam passes through the glass substrate upstream of the focusing point over a width of about 300μηη and at a distance of about 350 μιτι from the focusing point. This configuration example makes it possible to obtain a conveyance speed gain of 15% from about 6m / min to 7m / min at equal processing performance.

Of course, the present invention is not limited to the illustrated example but is susceptible of various variations and modifications that will occur to those skilled in the art.

Claims

1. Device for heat treatment (1) of a coating (R) deposited on a substrate (S) comprising heating means (10) facing which the substrate can be moved, said heating means (10) being arranged for heating an area coating of the coating on the first face of the glass substrate, characterized in that said heat treatment device further comprises a preheating means (10 ') arranged to heat the coating of said moving substrate upstream of the heating zone on a zone Preheating

2. heat treatment device according to claim 1, characterized in that the heating means (10) are arranged to raise the coating temperature from 300 to 700 ° C, in particular from 500 to 650 ° C for a period of time by at most 1 ms and in that the preheating means (10 ') are arranged to raise the temperature of the coating (R) by at most one-third of the temperature reached by the coating via heating means during a lapse of time. time of up to 50 ms.

3. Heat treatment device according to one of the preceding claims, characterized in that it further comprises a recycling device (RC) for using the unabsorbed portion of the energy supplied by the heating means (10). ) to serve as a preheating means.

4. Heat treatment device according to one of the preceding claims, characterized in that the heating means (10) comprise a laser system (10b) comprising at least one laser generator (L).

5. Heat treatment device according to claim 4, characterized in that the laser system (10b) is positioned to be angularly offset from the perpendicular to the glass substrate.

6. Heat treatment device according to one of claims 1 to 3, characterized in that the heating means (10) comprise a plurality of flash lamps (LD).

7. Heat treatment device according to claim 4 or 6, characterized in that the recycling device (RC) is a reflective element (20) arranged to reflect the portion of the unabsorbed light beam (f) by the substrate and direct it on the coating of said traveling substrate to act as a preheating means.

8. Heat treatment device according to claim 7, characterized in that said reflector element (20) is a mirror (M) arranged opposite the face opposite to the face of said substrate carrying the coating.

9. Heat treatment device according to claim 8, characterized in that said reflective element (20) is a mirror (M) flat extending parallel to the plane of the substrate.

10. Heat treatment device according to claim 8, characterized in that said reflector element (20) is a curved mirror (M).

1 1. Heat treatment device according to one of claims 8 to 10, characterized in that said reflective element (20) is movable in at least one degree of freedom.

12. Heat treatment device according to claim 1 1, characterized in that the degree of freedom is a translation in a plane perpendicular to the plane of the substrate.

13. Heat treatment device according to claim 1 1, characterized in that the degree of freedom is a rotation relative to an axis perpendicular to the direction of travel.

14. Heat treatment device according to claim 7, characterized in that said reflector element (20) is arranged to reflect a beam in two distinct directions for orienting the unabsorbed beam (f) on either side of the point of focus.

15. Heat treatment device according to claim 14, characterized in that said reflective element (20) is a mirror (Μ ') comprising two sections forming between them an angle, the faces of the outer corner being reflective.

16. Heat treatment device according to claim 14, characterized in that said reflector element (20) comprises a cylinder block (200) of triangular section having two parallel wafer faces (201) and three side faces (202), two adjacent side faces being reflective.

17. Heat treatment device according to claim 7, characterized in that said reflective element (20) is a reflective layer (21) deposited on the face of said substrate (S) opposite the face bearing the coating (R).

18. Heat treatment device according to one of the preceding claims, characterized in that the substrate (S) extends in a first dimension and a second dimension orthogonal to the first dimension, said substrate traveling in a collinear direction at most. large of the two dimensions, and in that the heating means extends in a direction orthogonal to the direction of travel.

19. Heat treatment device according to one of the preceding claims, characterized in that the preheating zone and the heating zone are disjoint.

20. Heat treatment device according to one of the preceding claims, characterized in that said substrate extends in a first direction which is its length and a second direction which is its width and which is orthogonal to the first direction, said substrate scrolling in the direction of its length, the preheating zone and the heating zone extending over the entire width of the substrate.