Device for texturing the surface of a moving strip

Abstract

The invention relates to a device for texturing the surface of a strip moving at a line speed V, the device comprising a strip path P1, a frame adjacent to the strip path P1, a plurality of inkjet print heads H1, H2… Hn distributed along and above the path P1, a plurality of radiation-curing modules M1, M2… Mn distributed along and above the path P1, each radiation-curing module Mi being positioned at a distance Li downstream of the inkjet print head Hi so that the radiation-curing modules and the inkjet print heads alternate, the plurality of inkjet print heads and the plurality of radiation-curing modules being connected to the frame so that a plurality of distances Li can be adjusted by linear translation, along the path P1, of the inkjet print head Hi and / or of the radiation-curing module Mi. The invention also relates to the processes thereof.

Description

[0001] Device for texturing the surface of a moving strip

[0002] The present invention relates to a device for texturing the surface of a moving strip. The present invention also relates to the method for texturing the surface of a moving strip and to a method for modifying on demand the surface texture of a moving strip.

[0003] Coil coating is a continuous, automated process for coating a strip before it is transformed into end products. The strip is delivered in coil form, preferably from a rolling mill. The coil is positioned at the beginning of the coil-coating line, and in one continuous process, the coil is unwound, attached to the tail of the previous strip, cleaned, pre-treated, primed, and painted before being recoiled on the other end and packaged for shipment.

[0004] The product obtained by this process is a prepainted strip, also referred to as coil-coated strip, prefinished strip or pre-coated strip. Prepainted metal is commonly used in construction applications as well as appliances.

[0005] The aspect of the prepainted strip is given by the aspect of the final paint applied on the strip. The aspect can notably be smooth. It is also known to use paints whose surface shrinks during curing, forming wrinkles that give a unique mat aspect and a texture pattern to the product. However, this wrinkled aspect is difficult to control and to reproduce as it depends on numerous process parameters, notably the line speed and the curing conditions, and as these process parameters have to be adjusted from time to time to adapt the process conditions to the product features. Moreover, the texture pattern is limited by the characteristics of the paint and cannot be customized.

[0006] The aim of the present invention is therefore to remedy the drawbacks of the prior art by providing a device, and a corresponding method, for generating on a moving strip a surface texture that can be modified on demand and whose aspect is independent of the process conditions of the coil-coating line. For this purpose, a first object of the present invention consists of a device for texturing the surface of a strip moving at a line speed V, the device comprising:

[0007] - A strip path Pi,

[0008] - A frame adjacent to the strip path Pi,

[0009] - A plurality of inkjet print heads Hi , H2... Hn distributed along and above the path Pi,

[0010] - A plurality of radiation-curing modules Mi, M2... Mn distributed along and above the path Pi, each radiation-curing module Mi being positioned at a distance Li downstream of the inkjet print head Hi so that the radiationcuring modules and the inkjet print heads alternate, the plurality of inkjet print heads and the plurality of radiation-curing modules being connected to the frame so that a plurality of distances Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi.

[0011] The device according to the invention may also have the optional features listed below, considered individually or in combination:

[0012] - each distance Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi,

[0013] - the device further comprises a servomechanism designed for, and capable of adjusting each adjustable distance Li on demand independently of the other adjustable distances,

[0014] - the device further comprises a servomechanism designed for, and capable of adjusting the plurality of adjustable distances Li simultaneously as a linear function of the line speed V,

[0015] - the radiation-curing modules Mi, M2... Mn are designed for, and capable of, pinning ink drops deposited on the strip by the inkjet print heads,

[0016] - the radiation-curing modules Mi, M2... Mn are LED light-curing devices,

[0017] - the device further comprises a final inkjet print head located adjacently downstream of the radiation-curing module Mn,

[0018] - the device further comprises a final radiation-curing device positioned at a distance Lf downstream of the last inkjet print head and connected to the frame so that the distance Lf can be modified by linear translation, along the path Pi, of the last inkjet print head and / or of the final radiation-curing device,

[0019] - the device further comprises a servomechanism designed for, and capable of adjusting the distance Lf on demand,

[0020] - at least some of the radiation-curing modules Mi are fixed to the inkjet print head Hi+i located adjacently downstream,

[0021] - the frame comprises two rails positioned parallel to, and on both longitudinal sides of, the strip path Pi,

[0022] - the device comprises a plurality of gantries, mobile in translation on the rails, each gantry bearing an inkjet print head Hi and / or a radiationcuring module Mi,

[0023] - all the radiation-curing modules Mi, M2... Mn of the plurality of radiationcuring modules and all the inkjet print heads Hi , H2... Hn of the plurality of inkjet print heads are positioned on gantries mobile in translation on the rails, except possibly the first inkjet print head Hi.

[0024] A second object of the invention consists of a process for texturing the surface of a strip moving at a line speed V with a device according to the invention, the process comprising:

[0025] - (i) selecting a plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable,

[0026] - (ii) setting initial values of the distances Li depending on a texture pattern and on a set line speed,

[0027] - (iii) collecting the line speed V,

[0028] - (iv) printing the texture pattern, the printing step comprising sequentially depositing, on the strip, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiation-curing module located adjacently downstream,

[0029] - (v) adjusting the distances Li simultaneously as a linear function of the line speed V. A third object of the invention consists of a process for modifying the texture of the surface of a moving strip moving with a device according to the invention, the process comprising:

[0030] - (i) selecting a plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable,

[0031] - (ii) setting initial values of the distances Li depending on a first texture pattern and on a set line speed,

[0032] - (iii) printing the first texture pattern, the printing step comprising sequentially depositing, on the strip moving at the set line speed, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiation-curing module located adjacently downstream,

[0033] - (v) modifying at least one adjustable distance Li independently of the other distances, depending on a second texture pattern.

[0034] As it is apparent, the invention is based on the alternation of inkjet print heads and radiation-curing modules along the strip path. This alternation allows to apply successive ink layers with the ink of each layer being pinned before the next layer is applied. Depending on the distance between the inkjet print head and the radiation-curing module, the ink drops can be pinned at different stages of progress of their spread on the strip. An early pinning provides a pronounced texture while a late pinning or no pinning at all provides a smooth texture. As each ink layer has its own pinning, the succession of ink layers gives a unique surface texture to the strip. Furthermore, as a plurality of head - module distances can be adjusted, the pinning of a plurality of ink layers can adjusted on the fly. Consequently, the surface texture can be modified on demand and / or can be maintained while process conditions of the coil-coating line are modified.

[0035] The invention will be better understood by reading the following description, which is provided purely for purposes of explanation and is in no way intended to be restrictive, with reference to Figure 1 , which is a schematic illustration of the device according to the invention. It should be noted that spatially relative terms such as “above”, “below”... as used in this application refer to the positions and orientations of the different constituent elements of the device when the latter is installed on a coil-coating line. Spatially relative terms “upstream” and “downstream” as used in this application refer to the position of a constituent element of the device in relation to another with respect to the moving direction of the strip or the orientation of the strip path.

[0036] The methods and the device according to the invention are intended for strips, such as metallic strips. Steel, either carbon steel or stainless steel, aluminium, copper are examples of metallic strips. In particular, steel strips can be bare or coated with a metallic coating, on either one or two sides of the strip. Examples of possible metallic coated steels are galvanized steel, steels coated with a zinc alloy comprising 5 wt.% of aluminum (Galfan®), steels coated with a zinc alloy comprising 55 wt.% of aluminum, about 1.5 wt.% of silicon, the remainder consisting of zinc and inevitable impurities due to the processing (Aluzinc®, Galvalume®), steels coated with an aluminum alloy comprising from 8 to 11 wt.% of silicon and from 2 to 4 wt.% of iron, the remainder consisting of aluminum and inevitable impurities due to the processing (Alusi®), steels coated with a layer of aluminum (Alupur®), steels coated with a zinc alloy comprising 0.5 to 20% of aluminium, 0.5 to 10% of magnesium, the remainder consisting of zinc and inevitable impurities due to the processing (Magnelis®, Optigal®), steels coated with an alloy comprising aluminium, magnesium, silicon, possible additional elements, the remainder consisting of zinc and inevitable impurities due to the processing.

[0037] The strips can also be coated with a paint film, on either one or two sides of the strip, possibly above a metallic coating, as described above. The paint film is generally polymer-based and comprise at least one layer of paint. The paints traditionally used in this domain are solvent-based paints. They usually comprise at least one polymer selected among melamine cross-linked polyesters, isocyanate cross-linked polyesters, polyurethanes, epoxy, halogenated derivatives of vinyl polymers and mixtures thereof. Radcure paints are also possible. Radcure paints are solvent-free paints whose curing process is triggered by exposure to a high-energy UV light (UV curing), possibly in conjunction with suitable photoinitiators, or / and exposure to accelerated electrons (Electron Beam curing). Photoinitiators absorb UV light and generate free radicals. The latters react with double bonds of monomers causing chain reaction and polymerization. For IIV-C and electron beam (EB) curing, initiators are not required. The high radiant energy produces sufficient reactive species (radicals) for polymerization to proceed spontaneously. The monomers can be selected among acrylate or methacrylate.

[0038] The paint film can be formed, for example, by two successive layers of paints, namely a primer layer and a finish layer, which is generally the case in creating the film applied to the top face of the strip, or a single layer of paint, which is generally the case in creating the film applied to the bottom face of the strip. Other numbers of layers can be used in certain variants.

[0039] The texturing device, and the methods, according to the invention are designed for being installed, and implemented, on a production line. The latter can be, for example, a coil-coating line. A coil-coating line mainly comprises, sequentially along the path P of the moving strip, a first paint applicator and a first curing device. Preferably, it furthers comprises a second paint applicator and a second curing device.

[0040] The strip path P is the path followed by the strip S in the production line, in particular from its entry in the coil-coating line to its exit. The strip path P has a width and a length. Pieces of equipment are positioned along this path to perform operations on the strip. Such pieces of equipment thus each comprise a portion of strip path P and elements of the piece of equipment can be positioned along this portion of the strip path.

[0041] A paint applicator is a device that apply a wet film of paint on one or both sides of a strip with a preset thickness of paint. In the context of the invention, the technology of the paint applicator is not limited.

[0042] According to a variant, the paint applicator is a paint roll-coater. It is an automated machine that coat one or both sides of a strip with rotating rolls. It is designed so that the strip passes through the machine that applies a layer of paint to one or both sides of the strip. There are numerous designs of paint roll-coaters depending on the configuration of the coil-coating line, the types of paints being used, and the types of strips being coated. The person skilled in the art will know which design is best adapted to each case. Generally speaking, the paint rollcoater comprises a paint pan, a steel or ceramic pick up roll, and a rubber covered coating roll. The purpose of the paint pan is to contain, circulate and preferably heat the paint. The pick up roll can be partially immersed in the paint and can rotate in either a clockwise or a counter clockwise direction to pick the paint up and transfer it to the coating roll. The latter transfers the paint to the strip.

[0043] According to another variant, the paint applicator is a curtain coater. In that case, a curtain of paint is applied to the horizontal strip normally transverse to the curtain. The paint falls from a height under gravity from a curtain die or cascade while the strip is supported on a backing roller. This method is capable of achieving high line speeds and multilayer coatings.

[0044] Examples of other paint applicators are knife coater, dip or meniscus coater, slot coater, meter rod coater, slide coater.

[0045] The curing device cures the wet film of paint. In the context of the invention, the technology of the curing device is not limited. It can be a convection oven, an induction oven, an Ultra-Violet (UV) curing device, an Electron-Beam (EB) curing device.

[0046] The texturing device is preferably positioned on the coil-coating line downstream of the last curing device, i.e. the curing device which cures the final paint layer of the paint film, and upstream of the recoiler, which recoils the strip at the end of the line. In the case of a paint film formed by only one layer of paint, which is applied on the first paint applicator, the texturing device can be positioned between the first curing device and the second paint applicator.

[0047] With reference to Figure 1 , the texturing device 1 according to the invention first comprises a strip path Pi. The strip path Pi is the path to be followed by the strip S in the texturing device, in particular from its entry in the texturing device to its exit. The strip path Pi has a width and a length, the length being parallel to the moving direction of the strip. It also has an orientation which corresponds to the moving direction of the strip. It can be materialized by one guide roll or a plurality of guide rolls and / or it can be delimited by a surface on which the strip slides. Preferably, the strip path Pi is substantially flat and horizontal. When the texturing device is installed on the production line, the strip path Pi of the texturing device coincides with a portion of the strip path P of the production line.

[0048] Elements of the texturing device can be positioned along the strip path Pi to perform operations on the strip. For the sake of clarity, “along the strip path” means along the length of the strip path, i.e. along the moving direction of the strip. It does not mean across the strip path. From that perspective, the texturing device further comprises a plurality of inkjet print heads Hi, H2... Hn distributed along and above the strip path Pi. Each inkjet print head is designed for, and capable of, spraying droplets of ink on the moving strip according to a preset inkjet pattern. An inkjet pattern can be defined as the distribution, on the strip, of the ink drops deposited by the inkjet print head(s). An inkjet pattern can be repetitive or not. Each inkjet print head can have its own preset inkjet pattern. The inkjet pattern of a given inkjet print head can be selected independently of the others depending on the texture to be formed on the moving strip. The combination of the inkjet patterns of the selected inkjet print heads makes the general inkjet pattern of the moving strip.

[0049] An inkjet print head is a component of a printer through which the printer expels ink on demand. It can jet one or a plurality of colors or a clear ink. It can be, for example, a piezoelectric print head, a thermal print head or a valve jet print head. The inkjet print head can comprise built-in heaters to be capable of jetting high viscosity inks. It can have a variable drop volume capability to allow the creation of a range of drop sizes. The inkjet print head can be one single component spanning the width of the strip path, or it can be an assembly of components, the assembly spanning the width of the strip path. Alternatively, it can be one single component, or an assembly of components, mobile in linear translation along the width of the strip path. In addition to the inkjet print heads, the texturing device can comprise the remaining parts of the printer(s), e.g. ink tank(s), sensors, electronic board, positioning camera, air supply, translation frame...

[0050] Preferably, all inkjet print heads of the plurality use the same ink color or the same clear ink. A clear ink is favored to create a texture without hiding the color and / or the pattern of the paint film on which the ink is jetted.

[0051] The texturing device further comprises a plurality of radiation-curing modules Mi, M2... Mn distributed along and above the strip path Pi. Each radiation-curing module Mi is designed for, and capable of, pinning ink drops deposited on the strip by an inkjet print head. By “pinning”, it is meant that the radiation-curing module gels or cures at least the surface of the ink drops so that the drops stop spreading on the surface of the strip.

[0052] Each radiation-curing module Mi is positioned at a distance Li downstream of the inkjet print head Hi so that the radiation-curing modules and the inkjet print heads alternate. For the sake of clarity, it is meant by alternation that, along the strip path, the inkjet print heads and the radiation-curing modules succeed by turns. In other words, along the strip path, the inkjet print heads and the radiationcuring modules are positioned as follows: Pi, Mi, P2, M2... Pn, Mn. For the sake of clarity, the distance Li is defined as the distance between the vertical projection on the strip path Pi of the inkjet print head Hi and the vertical projection on the strip path Pi of the radiation-curing module Mi. Thanks to this alternation of inkjet print heads and radiation-curing modules, ink drops deposited by a given inkjet print head can be pinned by the radiation-curing module positioned downstream of the given print head, before additional ink is deposited by the next inkjet print head. Depending on the distance Li, and thus depending on the time elapsed since the ink deposit, the ink drops can be pinned at different stages of progress of their spread on the strip. An early pinning would provide a pronounced texture while a late pinning or no pinning at all would provide a smooth texture. Each radiationcuring module can have its own preset pinning pattern. The pinning pattern can be defined as a degree of spreading of the ink drops. The pinning pattern can be a constant or can vary over time. The pinning pattern of a given radiation-curing module can be selected independently of the others depending on the texture to be formed on the moving strip. The combination of the pinning patterns of the selected radiation-curing modules makes the general pinning pattern of the moving strip.

[0053] The combination of the inkjet patterns of the selected inkjet print heads and of the pinning patterns of the corresponding radiation-curing modules makes the texture pattern of the moving strip. In other words, the combination of the general inkjet pattern and the general pinning pattern makes the texture pattern of the moving strip. Preferably, the radiation-curing modules are LED light-curing devices. A LED light-curing device can be composed of LED modules which are subassemblies incorporating tens or hundreds of roughly millimeter square LEDs arranged in a matrix of rows and columns. Multiple LED modules are arranged in various configurations within the LED light-curing device to span the desired emitting length and width. LEDs can be UV / visible LEDs, with wavelengths typically of 365, 385, 395 or 405nm.

[0054] With reference to Figure 1 , the texturing device 1 according to the invention further comprises a frame 2. Overall, the frame is the rigid structure supporting other parts of the device so that the device can be positioned along the strip path P of the production line and attached to the production line. In the context of the invention, the way the frame is attached to the production line is not limited.

[0055] The frame is adjacent to the strip path Pi. Depending on the design of the frame, it can, for example, flank the strip path Pi, envelop it or surround it. In one variant of the invention, the frame comprises two rails 3 positioned parallel to, and on both longitudinal sides of, the strip path Pi. The two rails can be substantially in the plane of the strip path or they can be positioned above or below this plane. Alternatively, the frame can comprise stepper actuators.

[0056] The texturing device can further comprise a plurality of gantries 4 positioned on the frame and mobile in translation along the strip path Pi. Preferably, the gantries are mobile in translation on the rails of the frame. Alternatively, there are mobile in translation on the stepper actuators. Preferably, a portion of the gantry is positioned above the strip path Pi. The purpose of each gantry is to bear an inkjet print head Hi and / or a radiation-curing module Mi, as it will be detailed below.

[0057] The plurality of inkjet print heads and the plurality of radiation-curing modules are connected to the frame 2. In particular, they are connected so that a plurality of distances Li between an inkjet print head Hi and the radiation-curing module Mi positioned downstream can be adjusted by linear translation, along the strip path Pi, of the inkjet print head Hi and / or by linear translation, along the strip path Pi, of the radiation-curing module Mi. Consequently, the time elapsed between the ink deposit by the inkjet print head Hi and the pinning by the radiationcuring module Mi positioned downstream can be adjusted on demand. In particular, the time elapsed between the ink deposit by the inkjet print head Hi and the pinning by the radiation-curing module Mi positioned downstream can be maintained constant while the line speed is modified. Alternatively, for a given line speed, the time elapsed between the ink deposit by an inkjet print head Hi and the pinning by the radiation-curing module Mi positioned downstream can be modified to correct or modify the texture pattern of the moving strip. By “linear translation along the strip path” it is meant that the translation is linear and parallel to the length of the strip path, i.e. parallel to the moving direction of the strip.

[0058] Each distance Li between an inkjet print head Hi and the radiation-curing module Mi positioned downstream that can be adjusted by linear translation along the strip path Pi is referred to as an “adjustable distance”.

[0059] Practically speaking, having a plurality of adjustable distances means that a plurality of inkjet print heads and / or of radiation-curing modules are movable by linear translation, along the strip path Pi. In particular, these inkjet print heads and / or radiation-curing modules can be borne by the gantries 4.

[0060] According to a first variant of the invention, a plurality of distances Li can be adjusted by linear translation, along the strip path Pi, of some radiation-curing modules. These radiation-curing modules are referred to as “movable radiationcuring modules”. In particular, the movable radiation-curing modules are borne by gantries 4, as defined above, mobile in translation along the strip path Pi. Preferably, each gantry bears only one radiation-curing module. In this variant, the radiation-curing modules that are not movable and the inkjet print heads can be borne by the frame at fixed positions. More preferably, all the radiation-curing modules of the plurality of radiation-curing modules Mi, M2... Mn are movable by linear translation, along the strip path Pi, while all the inkjet print heads of the plurality of inkjet print heads Hi, H2... Hn are in a fixed position. Accordingly, each distance Li can be adjusted by linear translation, along the path Pi, of the radiation-curing module Mi. In other words, all distances Li can be adjusted by linear translation, along the path Pi, of the radiation-curing module Mi.

[0061] According to a second variant of the invention, a plurality of distances Li can be adjusted by linear translation, along the strip path Pi, of some inkjet print heads. These inkjet print heads are referred to as “movable inkjet print heads”. In particular, the movable inkjet print heads are borne by gantries 4, as defined above, mobile in translation along the strip path Pi. Preferably, each gantry bears only one inkjet print head. In this variant, the inkjet print heads that are not movable and the radiation-curing modules can be borne by the frame at fixed positions. More preferably, all the inkjet print heads of the plurality of inkjet print heads Hi, H2... Hn are movable by linear translation, along the strip path Pi, while all the radiation-curing modules of the plurality of radiation-curing modules Mi, M2... Mn are in a fixed position. Accordingly, each distance Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi. In other words, all distances Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi.

[0062] According to a third variant of the invention, a plurality of distances Li can be adjusted by linear translation, along the strip path Pi, of some inkjet print heads and some radiation-curing modules. In particular, the movable inkjet print heads and the movable radiation-curing modules are borne by gantries 4, as defined above, mobile in translation along the strip path Pi. The movable inkjet print heads and the movable radiation-curing modules can be borne by separate gantries. Alternatively, a given gantry can borne one radiation-curing module Mi and one inkjet print head Hi+1 positioned adjacently downstream. In this variant, the inkjet print heads that are not movable and the radiation-curing modules that are not movable can be borne by the frame at fixed positions.

[0063] In a preferred configuration of this variant, the first inkjet print head Hi is possibly stationary with respect to the frame and all the other inkjet print heads and the radiation-curing modules are borne by individual gantries positioned on the frame and mobile in translation along and above the strip path Pi. By “individual gantry”, it is meant that a gantry that bears either one single inkjet print head or one single radiation-curing module. Accordingly, each distance Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi. This configuration gives a maximum of flexibility in the respective positioning of the inkjet print heads and of the radiation-curing modules, thus giving a maximum of flexibility in the texture pattern of the moving strip and a maximum of flexibility in the management of the texture pattern.

[0064] In another configuration of this variant, the first inkjet print head Hi is possibly stationary with respect to the frame, all the other inkjet print heads and the radiation-curing modules are borne by individual or double gantries positioned on the frame and mobile in translation along and above the strip path Pi. By “double gantry”, it is meant a gantry that bears a radiation-curing module Mi and the inkjet print heads Hi+i located adjacently downstream. Accordingly, each distance Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi. The use of double gantries makes the texturing device more compact and simpler. More preferably, all the other inkjet print heads except the first inkjet print head Hi and all the radiationcuring modules except possibly the last radiation-curing module Mn are borne by double gantries.

[0065] As discussed above, adjusting the distances Li between the inkjet print heads Hi and the radiation-curing modules Mi positioned adjacently downstream is important to control and adjust the texture pattern. On the other hand, the distances between the radiation-curing modules Mi and the inkjet print head Hi+i positioned adjacently downstream is usually not a parameter for controlling and adjusting the texture pattern. Accordingly, at least some, if not all, of the radiationcuring modules Mi can be at a fixed position relative to the inkjet print head Hi+i located adjacently downstream. Preferably, at least some, if not all, of the radiation-curing modules Mi can be attached to the inkjet print head Hi+i located adjacently downstream.

[0066] In addition to the n inkjet print heads and the n radiation-curing modules, the texturing device can further comprise a final radiation-curing device 6 positioned at a distance Lf downstream of the last inkjet print head and connected to the frame so that the distance Lf can be modified by linear translation, along the path Pi, of the last inkjet print head and / or of the final radiation-curing device. The last inkjet print head referred to here can be the inkjet print head Hn or the final inkjet print head 5 described below. The final radiation-curing device 6 can fully cure the ink applied on the strip if it has not been fully cured by the n radiationcuring devices. The final radiation-curing device can be at a fixed position or mobile, according to the variants described above with regard to the n radiationcuring devices. As for the radiation-curing modules, the final radiation-curing device can be a LED light-curing device, as described above.

[0067] The texturing device can further comprise a final inkjet print head 5 located adjacently downstream of the last radiation-curing module Mn. This final inkjet print head is unrelated to a corresponding radiation-curing module that would pin the ink applied on the strip with the final inkjet print head. This final print head is useful to apply a last inkjet pattern before all the ink applied on the strip is fully cured in the final radiation-curing device. The final print head can be at a fixed position or mobile, according to the variants described above with regard to the n inkjet print heads.

[0068] To control and adjust the adjustable distances Li, and Lf if applicable, the texturing device can further comprise a control system.

[0069] In a first variant, the control system is designed for, and capable of adjusting each adjustable distance Li, and Lf if applicable, on demand independently of the other adjustable distances.

[0070] In a second variant, the control system is designed for, and capable of adjusting the plurality of adjustable distances Li, and Lf if applicable, simultaneously as a linear function of the line speed V.

[0071] In a third variant, the control system is designed for, and capable of both:

[0072] - adjusting each adjustable distance Li, and Lf if applicable, on demand independently of the other adjustable distances and

[0073] - adjusting the plurality of adjustable distances Li, and Lf if applicable, simultaneously as a linear function of the line speed V.

[0074] The control system can comprise a plurality of servomechanisms, preferably of servomotors. Preferably, each movable inkjet print head is connected to a servomechanism, preferably a servomotor. Preferably, each movable radiation-curing module is connected to a servomechanism, preferably a servomotor. Preferably, each gantry 4 is equipped with a servomechanism, preferably a servomotor, that allows for the linear movement of the gantry and adjust the distance Li, or Lf if applicable, depending on the position and movement of the other gantries.

[0075] The control system can be fed by a pattern module that breaks down the preset texture pattern into a combination of inkjet patterns and pinning patterns. As the pinning pattern of a given radiation-curing module is directly related to the line speed and to the distance between this radiation-curing module and the inkjet print head located adjacently upstream, the control system can easily adjust the distance between the module and the print head based on the pinning pattern and the line speed.

[0076] From a process perspective, the texturing device is used to texture the surface of a moving strip, in particular to apply a texture pattern on the strip surface.

[0077] In a first step, a texture pattern is preferably selected. In particular, a general inkjet pattern and a general pinning pattern are selected. More preferably, the inkjet patterns of all the inkjet print heads and the pinning patterns of all the radiation-curing modules are selected. A inkjet pattern, respectively a pinning pattern, can be void if the corresponding print head, respectively the corresponding radiation-curing module is not needed to form the texture pattern.

[0078] The different patterns can be manually designed. Alternatively, the different patterns can be automatically generated by analysis of a picture or drawing to be reproduced. The analysis can comprise converting the picture I drawing into a digital 2D grayscale representation and converting the digital 2D grayscale representation into a plurality of inkjet patterns and a plurality of pinning patterns. In particular, the gray scale can be divided into gray ranges and all the points of the texture having a gray value in a given gray range are assigned to the same inkjet pattern. In particular, the gray value variations can be analyzed to give to each point a slope value. The slope scale can be divided into slope ranges. All the points of the texture having a gray value in a given gray range and a slope value in a given slope range can be assigned to the same inkjet pattern and the same pinning pattern. The different patterns can also be automatically generated by analysis of a pre-existing texture to be reproduced. In that case, the analysis as described above can further comprise performing optical interferometry on the preexisting texture to obtain a digital 3D representation of the texture and converting the digital 3D representation into a digital 2D grayscale representation.

[0079] In a second step, the inkjet print heads Hi and the radiation-curing modules Mi that are needed to form the texture pattern are preferably identified. In particular, it is identified:

[0080] - which inkjet print heads Hi, for which the corresponding distance Li is adjustable, have to be used and, - which inkjet print heads Hi, for which the corresponding distance Li is fixed, have to be used, if any,

[0081] - which inkjet print heads are not needed, if any, and can be possibly turned off,

[0082] - which radiation-curing modules Mi, for which the corresponding distance Li is adjustable, have to be used,

[0083] - which radiation-curing modules Mi, for which the corresponding distance Li is fixed, have to be used, if any,

[0084] - which radiation-curing modules are not needed, if any, and can be possibly turned off,

[0085] Consequently, it is possible to identify pairs of inkjet print heads Hi and corresponding radiation-curing modules Mi for which the distance Li has to be adjusted to obtain the texture pattern, in particular to obtain the general pinning pattern, more particularly to obtain the pinning pattern of the corresponding radiation-curing module Mi.

[0086] In a third step, a plurality of inkjet print heads Hi, for which the corresponding distance Li is adjustable, are selected. This plurality preferably corresponds to the inkjet print heads Hi of the pairs of inkjet print heads Hi and corresponding radiation-curing modules Mi for which the distance Li has to be adjusted to obtain the texture pattern, which have been identified in the previous step. In the rest of the description, for easy reading, it will only be referred to this selected plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable. Indeed, only this selection needs to be considered to control and / or adjust the texture pattern according to the invention. Nevertheless, as explained above, the process can be implemented with additional inkjet print heads and possibly additional radiation-curing modules, for which the corresponding distances Li do not have to be adjusted.

[0087] The selection of the plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable leads de facto to the selection of the corresponding radiation-curing modules, since the ink applied by these inkjet print heads needs to be pinned in precise conditions.

[0088] In a fourth step, for each selected inkjet print head Hi for which the corresponding distance Li is adjustable, an initial value of the adjustable distance Li is set, depending on a texture pattern and on a set line speed Vo. Preferably, the initial value is set depending on the general pinning pattern. More preferably, the initial value is set depending on the pinning pattern of the corresponding radiationcuring module. As the pinning pattern is related to the time elapsed between the ink deposit by the inkjet print head Hi and the pinning by the radiation-curing module Mi positioned downstream, the initial value of the distance Li can easily be calculated for the set line speed. The set line speed can be the actual line speed at the time the process is implemented or a line speed selected by an operator before implementing the process.

[0089] In a fifth step, the texture pattern is printed. This step comprises sequentially depositing, on the strip moving at the set line speed, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiation-curing module located adjacently downstream. As explained above, this step can comprise sequentially depositing, on the strip moving at the set line speed, ink drops with other inkjet print heads and possibly pinning the inkjet drops with the corresponding radiation-curing modules located adjacently downstream.

[0090] During this printing process, some distances Li of the selected plurality of inkjet print heads can be adjusted for two different reasons: either to modify the texture pattern or to maintain the texture pattern when the line speed V is modified. The two types of adjustment are detailed below.

[0091] In a first variant of the invention, at any time during the printing process, the operator can decide to switch from a first texture pattern to a second texture pattern. Accordingly, the texture pattern is modified by adjusting at least one adjustable distance Li independently of the other distances. This adjustment is done by translating linearly, along the path Pi, the inkjet print head Hi and / or the radiation-curing module Mi. Other inkjet print heads and / or radiation-curing modules may have to be translated linearly to keep the adjustable distances other than Li unchanged, notably when double gantries are used. The adjustment can be done manually or automatically. Preferably, the adjusted value of the adjustable distance Li depends on a second texture pattern and on the set line speed. Preferably, the adjusted value depends on the general pinning pattern and on the set line speed. More preferably, the adjusted value depends on the pinning pattern of the corresponding radiation-curing module and on the set line speed. The adjusted value can be selected after:

[0092] - selecting the second texture pattern (as described in the first step),

[0093] - identifying the inkjet print heads Hi of the pairs of inkjet print heads Hi and corresponding radiation-curing modules Mi for which the distance Li has to be adjusted to obtain the second texture pattern (as described in the third step),

[0094] - identifying the initial values of the distances Li depending on the second texture pattern and on the set line speed

[0095] - comparing the initial values of the distances Li for the second texture pattern to the values of the distances Li for the first texture pattern.

[0096] The adjusted value is the value of the distance Li for the second texture pattern which differs from the value of the distance Li for the first texture pattern.

[0097] The numbers of adjustable distances Li to be adjusted depends on the differences between the first and second texture pattern. In particular, it depends on the number of initial values of the distances Li for the second texture pattern that differ from the values of the distances Li for the first texture pattern.

[0098] Once the at least one adjustable distance Li has been modified, the second texture pattern can be printed. This printing step comprises sequentially depositing, on the strip moving at the set line speed, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiationcuring module located adjacently downstream. As explained above, this step can comprise sequentially depositing, on the strip moving at the set line speed, ink drops with other inkjet print heads and possibly pinning the inkjet drops with the corresponding radiation-curing modules located adjacently downstream.

[0099] In a second variant, the line speed V is collected, i.e. it is made available on the basis of a measurement done otherwise. Preferably, the line speed is collected from a measurement device. It can be collected directly from a measurement device or through the management system of the coil-coating line. Preferably, it is collected by the control system. Preferably, the collection is done continuously. Preferably, the collection step and the printing step are done simultaneously. In case of line speed variation, all the distances Li are simultaneously adjusted as a linear function of the line speed V, so that the texture pattern is maintained despite the line speed variation. In particular, the adjusted values of the distances Li are recalculated, as in the step of setting their initial values, depending on the texture pattern and the new line speed.

[0100] In a third variant, the first and second variants are combined so that, at any line speed, the texture pattern can be maintained or modified.

Claims

CLAIMS1 ) Device (1 ) for texturing the surface of a strip moving at a line speed V, the device comprising:- A strip path Pi,- A frame (2) adjacent to the strip path Pi,- A plurality of inkjet print heads Hi , H2... Hn distributed along and above the path Pi,- A plurality of radiation-curing modules Mi, M2... Mn distributed along and above the path Pi, each radiation-curing module Mi being positioned at a distance Li downstream of the inkjet print head Hi so that the radiationcuring modules and the inkjet print heads alternate, the plurality of inkjet print heads and the plurality of radiation-curing modules being connected to the frame so that a plurality of distances Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi.2) Device according to claim 1 wherein each distance Li can be adjusted by linear translation, along the path Pi, of the inkjet print head Hi and / or of the radiation-curing module Mi.3) Device according to any one of claims 1 or 2 further comprising a servomechanism designed for, and capable of adjusting each adjustable distance Li on demand independently of the other adjustable distances.4) Device according to any one of the preceding claims further comprising a servomechanism designed for, and capable of adjusting the plurality of adjustable distances Li simultaneously as a linear function of the line speed V.5) Device according to any one of the preceding claims wherein the radiationcuring modules Mi, M2... Mn are designed for, and capable of, pinning ink drops deposited on the strip by the inkjet print heads.6) Device according to claim 5 wherein the radiation-curing modules Mi, M2... Mn are LED light-curing devices.7) Device according to any one of the preceding claims further comprising a final inkjet print head (5) located adjacently downstream of the radiationcuring module Mn.8) Device according to any one of the preceding claims further comprising a final radiation-curing device (6) positioned at a distance Lf downstream of the last inkjet print head (5) and connected to the frame (2) so that the distance Lf can be modified by linear translation, along the path Pi, of the last inkjet print head and / or of the final radiation-curing device.9) Device according to claim 8 further comprising a servomechanism designed for, and capable of adjusting the distance Lf on demand.10)Device according to any one of the preceding claims wherein at least some of the radiation-curing modules Mi are fixed to the inkjet print head Hi+1 located adjacently downstream.11 )Device according to any one of the preceding claims wherein the frame (2) comprises two rails (3) positioned parallel to, and on both longitudinal sides of, the strip path Pi and the device comprises a plurality of gantries (4), mobile in translation on the rails, each gantry bearing an inkjet print head Hi and / or a radiation-curing module Mi.12)Device according to claim 11 wherein all the radiation-curing modules Mi, M2... Mn of the plurality of radiation-curing modules and all the inkjet print heads Hi, H2... Hn of the plurality of inkjet print heads are positioned on gantries mobile in translation on the rails, except possibly the first inkjet print head Hi.13)Process for texturing the surface of a strip moving at a line speed V with a device according to any one of claims 1 to 12, the process comprising:- (i) selecting a plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable,- (ii) setting initial values of the distances Li depending on a texture pattern and on a set line speed,- (iii) collecting the line speed V,- (iv) printing the texture pattern, the printing step comprising sequentially depositing, on the strip, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiation-curing module located adjacently downstream,- (v) adjusting the distances Li simultaneously as a linear function of the line speed V.14) Process for modifying the texture of the surface of a moving strip moving with a device according to any one of claims 1 to 12, the process comprising:- (i) selecting a plurality of inkjet print heads Hi for which the corresponding distance Li is adjustable,- (ii) setting initial values of the distances Li depending on a first texture pattern and on a set line speed,- (iii) printing the first texture pattern, the printing step comprising sequentially depositing, on the strip moving at the set line speed, ink drops with each selected inkjet print head and pinning the inkjet drops with the corresponding radiation-curing module located adjacently downstream,- (v) modifying at least one adjustable distance Li independently of the other distances, depending on a second texture pattern.

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