CN111032590A

CN111032590A - Improved heat treatment equipment

Info

Publication number: CN111032590A
Application number: CN201880056490.3A
Authority: CN
Inventors: C.奥扎南; E.米蒙; J.斯科尔斯基; L.卡诺瓦
Original assignee: Saint Gobain Glass France SAS
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2017-08-30
Filing date: 2018-08-29
Publication date: 2020-04-17
Also published as: FR3070387A1; WO2019043334A1; EP3676230A1; KR20200046056A

Abstract

The invention relates to a heat treatment device (1) for heat treating a coating (R) applied to a substrate (S), comprising a heating device (10) through which the substrate can be moved, said heating device (10) being designed to heat the coating on a first side of the glass substrate, characterized in that it further comprises a preheating device (10') designed to heat the coating of the moving substrate upstream of the heating zone.

Description

Improved heat treatment equipment

Technical Field

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

Background

It is known to achieve local and rapid annealing (rapid heating) of a coating applied to a flat substrate. For this purpose, the substrate with the coating to be annealed is passed under a heating device, such as a flash lamp or a plasma torch or a laser line, which is arranged on the substrate with the coating.

Rapid annealing allows the thin coating to be heated to high temperatures on the order of hundreds of degrees while retaining the underlying substrate. The speed of passage is of course preferably as high as possible, advantageously at least a few meters per minute.

For example, in the laser line used, the line comprises at least one laser generator providing a laser beam. The laser beam is focused so as to locally increase the thermal power provided by the laser generator.

This annealing method, whether using a laser or a flash lamp or other methods, has the disadvantage of a high energy consumption, which increases with the increase in line capacity, in particular in processing speed. This high energy consumption means high costs.

Disclosure of Invention

The present invention therefore seeks to solve these drawbacks by providing a heat treatment apparatus for rapid annealing that is more efficient from an energy level point of view and less expensive.

To this end, the invention relates to a thermal treatment apparatus for thermally treating a coating applied to a substrate, comprising heating means through which the substrate can be moved, said heating means being designed to heat a coating zone on a first side of a glass substrate, characterized in that it further comprises preheating means designed to heat the moving coating of said substrate upstream of a heating zone.

The invention offers the advantage of preheating the coating, thereby making it possible to reduce costs, since it is possible to use low-power heating devices or to use heating devices which are not very good. This use also increases the speed of movement because the coating is preheated.

According to one example, the heating device is designed to raise the temperature of the coating from 300 ℃ to 700 ℃, in particular from 500 ℃ to 650 ℃, in a time of at most 1 ms, and the preheating device is designed to raise the temperature of the coating by one third of the temperature reached by the heating device in a time of at most 50 ms.

According to one example, the apparatus further comprises a recirculation device, making it possible to use the non-absorbed part of the energy provided by the heating device as a preheating device.

According to one example, the heating device comprises a laser system comprising at least one laser generator.

According to one example, the laser system is positioned at an angular offset relative to a perpendicular to the glass substrate.

According to one example, the heating device comprises a plurality of flash lamps.

According to one example, the recycling device is a reflector element designed to reflect part of the light beam that is not absorbed by the substrate and to direct it onto the coating of the moving substrate in order to act as a preheating means.

This example advantageously makes it possible to have only one device for performing heating and preheating, making it possible to reduce costs as much as possible. This also makes it possible to have a simpler heat treatment apparatus, since only the heating device is parameterized.

According to one example, the reflector element is a mirror positioned facing a face of the substrate opposite to the coated face.

According to one example, the reflector element is a flat mirror extending parallel to the substrate plane.

According to one example, the reflector element is a curved mirror.

According to one example, the reflector element is movable in at least one degree of freedom.

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

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

According to one example, the reflector element is designed to reflect the light beam in two different directions, allowing the unabsorbed light beam to be directed on each side of the focus point.

According to one example, the reflector element is a mirror comprising two parts forming an angle between them, the outer angled face being reflective.

According to one example, the reflector element comprises a cylinder of triangular cross-section comprising two parallel edge faces and three side faces, two adjacent side faces being reflective.

According to one example, the reflector element is a reflective layer coated on a face of the substrate opposite to the coated face.

According to one example, the substrate extends in a first dimension and a second dimension orthogonal to the first dimension, the substrate is moved in a direction collinear with the larger of the two dimensions, and the laser beam extends in a direction orthogonal to the direction of movement.

According to one example, the preheating zone and the heating zone are separate.

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

Drawings

Further details and advantages will become apparent from the description given hereinafter by way of indicative, completely non-limiting manner, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a thermal processing apparatus according to the present invention;

fig. 2 is a schematic view of a heat treatment apparatus using a laser technique according to a first embodiment of the present invention;

figures 3 and 4 are schematic views of alternative forms of heat treatment apparatus according to a first embodiment of the invention;

FIG. 5 is a schematic view of a heat treatment apparatus according to a second embodiment of the present invention; and

fig. 6 is a schematic view of a thermal processing apparatus using a flash lamp technology according to a first embodiment of the present invention.

Detailed Description

Fig. 1 shows a heat treatment apparatus 1 for a substrate S according to the present invention. The treated substrate S is, for example, a very wide glass substrate, for example a flat glass sheet of "giant" size (6 m x 3.21 m) produced by the float glass process. Of course, the heat treatment apparatus 1 for the substrate S according to the present invention may be applicable to substrates of different sizes.

The heat treatment apparatus 1 comprises a transfer device 2, which transfer device 2 allows to transfer a substrate S, for example a glass substrate. Such a conveyor 2 may take the form of two parallel rails on which a chassis is arranged to provide support for the substrate S. It may also be provided that the transport means 2 take the form of two parallel rails on which wheels are mounted to allow the substrate to have mobility. Wheels are then attached to the motor to allow the substrate to move.

For a glass substrate in the form of a "giant" size (6 m x 3.21.21 m) sheet of flat glass, it will be specified that the conveyance be performed in a first direction extending along the longest of the two dimensions of the sheet. In the case of a sheet of "jumbo" size (6 m x 3.21 m), the sheet would be defined to have a length of 6 m and a width of 3.21 m, and the conveyor 2 would be defined to allow the glass sheet to move along its length, which means along its length.

The heat treatment apparatus 1 further comprises heating means 10. These heating means 10 can take various forms and are advantageously designed to provide energy E in order to raise the temperature of the coating within the heating zone within a time interval of at most 1 ms, the temperature increase being in the interval 300 ℃ to 700 ℃, in particular 500 ℃ to 650 ℃. These heating means 10 comprise a flash lamp system 10a, for example 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 providing said energy. The heating region extends over the entire width of the substrate.

In the case of the laser system 10b visible in fig. 2, each laser generator L may employ solid-state or diode laser or disc laser technology, which is known as a perfect combination of solid-state and diode lasers, enabling higher beam quality and higher performance. These heating means 10 allow the coating R or layer applied to the substrate S to be annealed. The substrate S comprises a first side and a second side, the first side being the side supporting the layer/coating R to be annealed. The second face is the face that contacts the conveyor. The substrate S is preferably a substrate transparent to the laser wavelength.

The laser generator L provides a light beam F through the optical element in order to obtain the light beam F in the form of a line having a length, for example, but not limited to, 10cm to 50cm and a width of less than 100 μm.

In the case of a plurality of laser generators L, these are arranged adjacent to each other, thereby having a cumulative effect in forming a single very long line. In this case, in order to be able to adjust the alignment of these different beams so as to obtain a laser line that is as uniform as possible, an alignment system (not shown) is provided.

In the case of the flash lamp system 10a shown in fig. 6, the system 10 comprises a plurality of discharge lamps LD providing broad-spectrum pulsed light to provide energy. Several tubes are placed side by side to form an area illuminated by a flash of several tens of centimeters. In order to guide the light to the area to be irradiated, reflective caps C are provided at the rear and side of the lamp tube to reflect the light forward. The reflective cap C is advantageously designed to concentrate the light rays without excessive divergence. The light pulse duration is less than 1 ms. This flash lamp technology allows for handling a larger area for a given lamp layout than for a laser system.

Skillfully, the present invention proposes to provide a preheating device 10' upstream of the heating device 10 for preheating the coating R. These preheating devices 10' are designed to raise the temperature of the coating R in the preheating zone by approximately 100 ℃ and at most by one third of the temperature reached by the heating device 10, in a time interval of 1 ms up to 50 ms. The preheating zone is distinct and separate from the heating zone, which means that there is a space between the two zones, which space is not heated or preheated. The pre-heating region extends over the entire width of the substrate.

These preheating devices 10 'can be, for example, laser lines or flash lines or resistive plates of lower power than the heating devices and are preferably arranged continuously upstream of the heating devices 10, which means that the spacing between the preheating devices 10' and the heating devices 10 is as small as possible to avoid heat losses.

Thus, for example and without limitation, it is possible to have a heat treatment apparatus 1, which heat treatment apparatus 1 comprises a resistance plate as preheating device 10 ' and a flash lamp system as heating device 10, or comprises a laser system as preheating device 10 ' and a flash lamp system as heating device 10, or comprises a flash lamp system as preheating device 10 ' and a laser system as heating device 10.

Skillfully, the present invention proposes to use the existing heating device 10 for preheating. In the case of the heat treatment using the laser, an additional step of heat-treating the substrate S with the laser beam F of the laser generator L is skillfully performed, as shown in fig. 2.

According to the first embodiment, the heat treatment apparatus 1 further includes a recycling apparatus RC to allow the glass substrate to be preheated. For this purpose, the heat treatment device 1 comprises a reflector element 20. In this case, the reflector element 20 is a mirror M. The mirror M is disposed below the substrate S. This first embodiment will employ an example of a heating device 10 comprising at least one laser generator L, which is non-limiting and applicable to a flash lamp or plasma torch or any other heating device 10. This arrangement allows the portion f of the laser beam that is not absorbed by the coating R and the substrate S to be acted upon, which substrate is transparent at the wavelength used by the heating device 10. This unabsorbed laser beam f is defocused because the focusing takes place at the level of the coating R to be annealed. Therefore, the mirror M is positioned so that the laser beam f that is not absorbed is reflected. This reflection is designed so that the reflected unabsorbed beam F' is reflected toward the glass substrate S upstream of the point where the laser beam F is focused. This configuration allows the coating applied to the glass substrate S to be heated before it moves past the localized laser beam. This preheating therefore allows a reduction of the laser power, since the power is better utilized, or the transfer speed can be increased.

In order to avoid damage to the laser generator L, the latter would be mounted in such a way that the laser beam F is not perpendicular to the glass substrate. This arrangement advantageously makes it possible to use a mirror M and to position it parallel to the plane of the glass substrate S. This arrangement more specifically makes it possible to use a simple plane mirror M to reflect the unabsorbed laser beam f.

However, the mirror M may be placed obliquely with respect to the plane of the glass substrate S. Further, the mirror M is not limited to a flat mirror, but may be curved, convex or concave in shape.

In order for the unabsorbed laser beam to be reflected toward the glass substrate S upstream of the focusing point, the laser generator L will be positioned at an angular offset from the perpendicular to the glass substrate. The angle of incidence of the laser light on the glass substrate S will be between 5 ° and 15 °, preferably between 7 ° and 10 °.

Preheating is effective because the reflected defocused beam F' has a significantly lower power per unit area than the focused beam F. This reduction in the power per unit area makes it impossible to anneal the coating R applied to the glass substrate S, but is sufficient to allow the coating of said substrate S to be preheated.

The power per unit area can be modified. In particular, the reflected beam f' is defocused, which means that the surface area of the beam is not constant. Therefore, by changing the distance D between the mirror M and the glass substrate S, the surface area of the reflected laser beam f' at the substrate level and the power per unit area are changed. By increasing the distance D between the mirror M and the second face of the glass substrate S, i.e., by translating the mirror M in a direction perpendicular to its plane, the width La of the reflected beam f' of the preheated glass substrate S is increased, and the distance D between the preheating region and the focus point is also increased. Also, the inclination of the plane of the mirror M can be changed, thereby changing the position of preheating. By changing the inclination of the mirror M, the distance between the mirror M and the pre-heat coat is changed so that the power can be varied.

In the case of a flash lamp system, the reflector element 20 may also be used to reflect light that is not used during processing and to perform preheating. In this case the reflector element 20, i.e. the mirror, is wider in order to accommodate a large illuminated area. Furthermore, the distance between the reflector element 20 and the glass substrate S coated with the coating is very small in order to limit the divergence as much as possible.

In an alternative form of this first embodiment, the means for achieving preheating also allow post-heating, so as to allow slow cooling of the treated coating. For this purpose, the reflector element 20 is designed to be able to reflect the unabsorbed light beam f in two different directions, as shown in fig. 3.

In the first embodiment, the reflector element 20 of this second embodiment is a curved mirror M'. This mirror M' comprises two portions M forming an angle between them. The outer corner face (the larger of the two angles) is reflective, while the inner corner face allows the presence of means for supporting the reflector element 20.

In a second embodiment shown in fig. 4, the reflector element 20 is a mirror M "in the form of a cylinder 200 of triangular cross-section. The mirror M "comprises two parallel edge faces 201 and three side faces 202. Two adjacent sides are reflective.

This positioning of the reflector element 20 advantageously allows the non-absorbed beam f to be split into two parts. The first divided portion is directed upstream of the focus point and the second divided portion is directed downstream of the focus point. The second divided portion directed downstream of the focusing point makes it possible to improve cooling if the first divided portion directed upstream allows the glass substrate S to be preheated. In fact, it causes the temperature to drop more slowly after heat treatment.

The reflector element 20 may be designed and positioned in such a way as to divide the non-absorbed beam f equally or to divide it unequally in order to favor either the upstream or downstream part of the focal spot. In order to change the ratio at which the non-absorbed beam f is divided by the reflector element 20, the position of the apex is changed. To control the power per unit area, the tilt angles of the two reflective portions are used and modified. The tilt angles may have different values and may be modified independently.

The thermal processing apparatus 1 further includes a beam shield BD. The beam mask BD is located in the path of the reflected unabsorbed beam f'. More specifically, the beam shield BD is disposed above the glass substrate S. This arrangement allows the beam shield BD to be an element that prevents the reflected unabsorbed beam f' from propagating. The shield BD is advantageously made of a heat-resistant material, such as ceramic or refractory metal, and/or can be cooled. In case the non-absorbed beam is split into two parts, there may be two beam shields BD.

In a second embodiment, visible in fig. 5, the reflector element 20 is a reflective layer 21. The reflective layer 21 is arranged on a second side of the glass substrate S, i.e. the side opposite to the side with the coating R. To be effective, the reflective layer 21 has a reflectivity of at least 70%, preferably at least 80%.

Therefore, the reflective layer 21 reflects the light beam f that is not absorbed. This reflection is similar to that of the mirror M described in the first embodiment, i.e., the light beam f that has not been absorbed is reflected upstream of the focusing point.

In a non-limiting example of the configuration, the glass substrate is 4 mm thick, the laser has a power of 433W and a width of 80 μm, the reflectivity of the reflective layer is 80%, and the incident angle 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 focus point, with a width of about 300 μm and a distance of about 350 μm from the focus point. This example of configuration makes it possible to increase the transfer speed by 15%, from about 6 m/min to 7 m/min, with the same processing performance.

Of course, the invention is not limited to the examples shown, but may be varied and modified in various ways apparent to those skilled in the art.

Claims

1. A heat treatment apparatus (1) for heat treating a coating (R) applied onto a substrate (S), comprising a heating device (10) through which the substrate can be moved, the heating device (10) being designed to heat a heating zone of the coating on a first side of the glass substrate, characterized in that the heat treatment apparatus further comprises a preheating device (10') designed to heat the coating of the moving substrate in the preheating zone upstream of the heating zone.

2. The heat treatment apparatus according to claim 1, characterized in that the heating device (10) is designed to raise the temperature of the coating from 300 ℃ to 700 ℃, in particular from 500 ℃ to 650 ℃, in a time interval of at most 1 ms, and the preheating device (10') is designed to raise the temperature of the coating (R) by at most one third of the temperature reached by the coating through the heating device in a time interval of at most 50 ms.

3. Heat treatment apparatus according to any one of the preceding claims, characterized in that it further comprises a recirculation apparatus (RC) making it possible to use the non-absorbed part of the energy supplied by the heating means (10) as preheating means.

4. Heat treatment apparatus according to any one of the preceding claims, wherein said heating device (10) comprises a laser system (10 b) comprising at least one laser generator (L).

5. The thermal processing apparatus according to claim 4, characterized in that the laser system (10 b) is positioned in an angularly offset manner with respect to the perpendicular to the glass substrate.

6. The thermal processing apparatus according to any of claims 1 to 3, characterized in that said heating means (10) comprise a plurality of flash Lamps (LD).

7. Heat treatment apparatus according to claim 4 or 6, characterized in that the recycling device (RC) is a reflector element (20) designed to reflect the part of the beam (f) not absorbed by the substrate and to direct it onto the coating of the moving substrate so as to act as a preheating means.

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

9. The thermal processing apparatus according to claim 8, characterized in that the reflector element (20) is a flat mirror (M) extending parallel to the plane of the substrate.

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

11. Heat treatment apparatus according to any one of claims 8 to 10, characterized in that the reflector element (20) is movable in at least one degree of freedom.

12. The thermal processing apparatus of claim 11, wherein the degree of freedom is translation in a plane perpendicular to a plane of the substrate.

13. The thermal processing apparatus of claim 11, wherein said degree of freedom is rotation with respect to an axis perpendicular to the direction of movement.

14. Heat treatment apparatus according to claim 7, characterized in that the reflector element (20) is designed to reflect the light beam in two different directions, allowing the non-absorbed light beam (f) to be directed on each side of the focus point.

15. Heat treatment apparatus according to claim 14, characterized in that the reflector element (20) is a mirror (M') comprising two parts forming an angle between each other, the faces of the outer corners being reflective.

16. Heat treatment apparatus according to claim 14, characterized in that the reflector element (20) comprises a cylinder (200) of triangular cross-section, which cylinder comprises two parallel edge faces (201) and three side faces (202), two adjacent side faces being reflective.

17. Heat treatment apparatus according to claim 7, characterized in that the reflector element (20) is a reflective layer (21) applied to the side of the substrate (S) opposite to the side with the coating (R).

18. Heat treatment apparatus according to any one of the preceding claims, wherein the substrate (S) extends in a first dimension and a second dimension orthogonal to the first dimension, the substrate being moved in a direction collinear with the larger of the two dimensions, and the heating means extend in a direction orthogonal to the direction of movement.

19. The thermal processing apparatus of any of the preceding claims, wherein said preheating zone and said heating zone are separate.

20. The thermal processing apparatus of any of the preceding claims, wherein the substrate extends in a first direction and a second direction, the first direction being its length, the second direction being its width and being orthogonal to the first direction, the substrate being moved in its length direction, the pre-heating region and the heating region extending over the entire width of the substrate.