DEVICE AND METHOD FOR SURFACE TREATMENT OF AN elongated product FOR THE PURPOSE OF WIRE DRAWING

Description

[0001] The present invention relates to an installation and a method for treating the surface of a long product for wire drawing, after it has been exposed to an oxidizing atmosphere for some of its chemical elements, for example during a stay in a heat treatment furnace.

[0002] In the following text, the primary example of application of the invention will be the field of stainless steel wires and ribbons of all categories (austenitic, ferritic, austenitic-ferritic, etc.). However, it should be understood that this is not a limiting factor, and that the invention may be applied to other metals for which technical problems arise that are similar to those encountered with stainless steel wires and ribbons, in particular to the various classes of carbon steels and special alloys, especially ferrous ones.

[0003] Such long products are generally produced by a series of treatments including the heating of a semi-product (in particular a billet), hot rolling to produce the long product, winding of the long product into a ring which is then subjected to annealing, in a furnace under a reducing atmosphere or in a gas furnace under an oxidizing atmosphere.

[0004] The long product thus obtained is intended to undergo wire drawing treatment using a wire drawing die in order to improve the dimensional accuracy and mechanical properties of the long product.

[0005] The series of treatments carried out before wire drawing, particularly hot rolling and annealing if not performed under a completely reducing or inert atmosphere, leads to the formation of an oxide layer on the surface of the long product. The composition of these oxides varies considerably depending on the composition of the base metal and the conditions of their formation. Most commonly, oxides of the elements Fe, Cr, Mn, and Si are predominant in the case of stainless steels, but also of the elements Ni, Nb, and Cu if the grade contains these elements.

[0006] These undesirable oxides must be removed before wire drawing begins, in particular to prevent them from becoming embedded in the surface of the long product during wire drawing and leading to a poor surface finish.

[0007] It must be understood that the undesirable oxide layer referred to here is not the thin chromium oxide layer (known as the "passive layer") that forms spontaneously in air at room temperature on the surface of stainless steels, protecting them from oxidation. The problematic oxide layer, which we want to eliminate, is the one that forms when the product is exposed to high temperatures in an oxidizing atmosphere. Once this layer is removed, the surface of the stainless steel is exposed, and the protective passive layer of chromium oxides can quickly and spontaneously reform, restoring the steel to its stainless state under normal operating conditions.

[0008] Furthermore, long products require a surface preparation step before wire drawing to adjust their surface roughness. Adjusting the roughness ensures good adhesion of the soaps applied to the surface of the long product just before drawing, thus facilitating the drawing process.

[0009] Traditionally, the unwanted oxide layer is removed by means of a chemical or electrolytic pickling process, or a succession of such pickling processes.

[0010] Chemical pickling is carried out in one or more baths of hydrofluoric, hydrochloric, sulfuric, or nitric acid. Electrolytic pickling is typically carried out in a sodium sulfate bath or an acid bath (nitric or sulfuric).

[0011] Chemical pickling is the most effective process for removing unwanted oxides. This pickling is carried out on long products in the form of coils or in continuous lengths. Chemical pickling is also used to modify the surface roughness of long products to improve their suitability for wire drawing.

[0012] But it has many drawbacks.

[0013] In particular, chemical stripping consumes high quantities of acids, with, at best, very little possibility of recovering some of them for later reuse.

[0014] The infrastructure required for its execution, namely the successive pickling baths and their annexes, is expensive and cumbersome.

[0015] These facilities use hazardous products, particularly hydrofluoric acid. Their polluting liquid and solid waste (sludge containing oxides mixed with pickling liquids) must be stored and treated according to strict regulations, the stringency of which will only increase in the future, which is costly. The heated acid baths also release acidic vapors that must be neutralized. Nitric acid is also a source of NOx emissions that must be captured and treated.

[0016] The presence of hexavalent chromium in solution in pickling liquids also represents a significant risk to the health of personnel and to the environment: its levels in the liquids and personnel exposure are measured and monitored.

[0017] Furthermore, pickling times can be very long, on the order of several tens of minutes for grades of steel with high corrosion resistance.

[0018] Pickling long products in coil form reduces the footprint of pickling equipment, but it can lead to uneven product stripping. This is because the overlapping of the coils and the ties holding the coil together can prevent pickling agents from reaching certain areas of the product, and the innermost coils are less exposed to pickling agents than the outer coils.

[0019] We therefore examined possibilities of replacing, at least in some cases, the chemical or electrolytic pickling of long products with processes using a laser.

[0020] We know from document EP 3 544 760 A1, which forms the basis of the preamble to claim 1, a laser stripping installation.

[0021] We also know from US document 4 087 898 A, which forms the basis of the preamble to claim 13, of a long product whose roughness is controlled.

[0022] Documents CN 210816759 U, CN 210647767 U, CN 108405652 A and KR 101735006 B1 are known to describe installations for stripping metal wires using a plurality of lasers distributed around the wire. The lasers are arranged regularly around the circumference of a circle whose center is occupied by the wire to be treated.

[0023] This solution is not entirely satisfactory. Indeed, this solution alone does not guarantee complete removal of the oxide layer. Furthermore, replacing chemical pickling with laser treatment does not resolve the issue of wire roughness, and the pickling solution proposed in these documents produces a wire with a roughness that is not necessarily suitable for drawing. The roughness could then be adjusted by chemical pickling, but in such a case, the problems associated with chemical pickling, as mentioned above, would not be resolved.

[0024] One aim of the invention is therefore to propose an installation and process for treating a long metallic product which provides a long product suitable for wire drawing without additional operation, and which makes it possible to overcome the disadvantages of chemical pickling mentioned above.

[0025] To this end, the invention relates to an installation for processing a long, flowing metallic product for a wire-drawing step, the long product having at least one surface covered with a layer of oxides, characterized in that it comprises: a stripping assembly comprising at least one group of a plurality of lasers distributed around the moving long product, each laser being configured to emit beams onto the surface of the moving long product to strip it, each laser being intended for the treatment of an associated portion of the surface of the long product, a control unit suitable for acquiring information relating to the moving long product, the information including a speed of movement of the long product and at least one characteristic dimension of the long product in a plane orthogonal to an axis of movement of the long product, the control unit being configured for: determine operating parameters to be imposed on the stripping assembly to obtain the stripping of the oxide layer on the surface of the long product and to ablate a layer of metal of predetermined thickness on the surface of the long product, and in such a way as to obtain on the surface of the long product periodic roughness patterns, the width of the periodic patterns being between 5 µm and 1 mm, by comparison with experimental results pre-recorded in the control unit, and impose said operating parameters on said stripping assembly.

[0026] According to one embodiment, the lasers of the laser group or groups are distributed evenly around the long product in motion.

[0027] According to one embodiment, the operating parameters include an emission power of the lasers of the or each group and / or a laser / matter interaction time at each point on the surface of the long product.

[0028] Preferably, the stripping assembly includes a distribution system configured to shape the laser beams or to move the laser beams over the surface of the long product in such a way that the laser beams emitted by the plurality of lasers in the or each group cover the entire surface of the long product as it is moved.

[0029] According to one embodiment, the distribution system includes, for each laser of at least one group, an optical device configured to transform each beam emitted by the associated laser into a band impacting a portion of the surface of the long product.

[0030] Alternatively, the distribution system includes, for each laser in at least one group, a scanning device configured to move the beams generated by the associated laser over the surface of the long product, according to a determined scanning speed and scanning step, such that the beams emitted by each laser impact a portion of the surface of the long product.

[0031] Preferably, the operating parameters include the scanning speed and the scanning step of the scanning device.

[0032] According to one embodiment, the surface portion of the long product is delimited by two lines on the surface of the long product parallel to the scrolling axis.

[0033] Preferably, the stripping assembly comprises a first group of a plurality of first lasers distributed around the long product in motion and a second group of a plurality of second lasers distributed around the long product in motion, each second laser being downstream of each first laser of the first group with respect to the motion axis.

[0034] Generally, the first lasers are configured to strip the oxide layer from the surface of the long product and ablate a layer of metal of predetermined thickness from the surface of the long product, and the second lasers are configured to impart the predetermined roughness to the surface of the long product.

[0035] Preferably, the first lasers are continuous emission lasers, and the second lasers are either continuous emission lasers or lasers configured to emit pulsed beams, including nanosecond lasers.

[0036] The invention also relates to a method for treating, by a treatment installation according to the invention, a long metallic product in motion for a wire drawing step, the long product having at least one surface covered with a layer of oxides, comprising the following steps: acquisition by the control unit of information relating to the moving long product, the information including a speed of movement of the long product and at least one characteristic dimension of the long product in a plane transverse to an axis of movement of the long product, determination by the control unit, based on the information relating to the moving long product, of operating parameters to be imposed on the stripping assembly in order to obtain the stripping of the oxide layer on the surface of the long product and to ablate a layer of metal of predetermined thickness on the surface of the long product, and in such a way as to obtain on the surface of the long product periodic roughness patterns, the width of the periodic patterns being between 5 µm and 1 mm, by comparison with experimental results pre-recorded in the control unit,The stripping assembly is controlled by the control unit to impose the aforementioned operating parameters on the stripping assembly; the stripping assembly then emits laser beams onto the surface of the moving long product using lasers, according to the operating parameters determined by the control unit.

[0037] According to one embodiment, during the emission step, the laser beams are emitted by lasers distributed uniformly around the long product in motion.

[0038] Preferably, during the emission stage, the laser beams are shaped or moved over the surface of the long product by a distribution system of the stripping assembly, controlled by the control unit, such that the laser beams emitted by the plurality of lasers of the or each group cover the entire surface of the long product as it moves.

[0039] According to one embodiment, the distribution system includes, for each laser of at least one group, an optical device, the optical device transforms each beam emitted by the associated laser into a band impacting a portion of the surface of the long product.

[0040] Alternatively, the distribution system includes, for each laser in at least one group, a scanning device; this scanning device moves the beams generated by the associated laser onto the surface of the long product, according to a scanning speed and a scanning step determined and controlled by the control unit, so that the beams emitted by each laser impact a portion of the surface of the long product.

[0041] For example, the scanning device moves the beams in a first direction forming an angle between 0° and 90°, for example 45°, with the scroll axis, and in a second direction orthogonal to the first direction. The two directions are, for example, respectively orthogonal and parallel to the scroll axis, or each forms a non-zero angle with the scroll axis.

[0042] According to one embodiment, the surface portion of the long product is delimited by two lines on the surface of the long product parallel to each other, in particular parallel to the scrolling axis.

[0043] Preferably, the stripping assembly comprises a first group of a plurality of first lasers distributed around the moving long product and a second group of a plurality of second lasers distributed around the moving long product, each second laser being downstream of each first laser of the first group with respect to the moving axis, the emission step comprises the emission of laser beams by the lasers of the first group and the lasers of the second group onto the surface of the moving long product.

[0044] Generally, the first lasers remove the oxide layer from the surface of the long product and ablate a layer of metal of predetermined thickness from the surface of the long product, then the second lasers impart the predetermined roughness to the surface of the long product.

[0045] The invention also relates to a long metallic product intended to be drawn, the long product having on its surface periodic roughness patterns, the width of the periodic patterns being between 5 µm and 200 µm.

[0046] According to one embodiment, the periodic patterns consist of periodic striations, comprising a regular alternation of raised lines and furrows, or of patterns comprising a regular alternation of peaks and troughs in a first and second distinct directions.

[0047] Generally, the average height between crests and furrows, or the average height between peaks and troughs, is between 0.2 µm and 500 µm.

[0048] The long product is, in particular, a thread or a ribbon.

[0049] The long product is suitable for wire drawing without undergoing surface preparation treatment by chemical or mechanical pickling.

[0050] The invention will be better understood upon reading the following description, given with reference to the attached figures, among which: There Figure 1 schematically illustrates, in profile, a laser stripping installation according to one embodiment of the invention; The Figure 2 illustrates an example of laser arrangement around a moving product, according to one embodiment.

[0051] The processing facilities that will be described in detail and illustrated with examples will be essentially in reference to the processing of a stainless steel wire in scroll form, which has just undergone annealing in the form of a ring.

[0052] The treatment installation according to the invention which will be described can also be integrated into a continuous treatment line comprising more or less equipment than that which will be described, or be the subject of a separate installation specially dedicated to this treatment.

[0053] Also not shown are the devices typically found on such lines that do not play a major metallurgical role and, in any case, do not directly contribute to the processing carried out according to the invention. These include, in particular, wire guides and straighteners for feeding the long product, and accumulators that act as buffers between certain devices, each of which may require a different product feed speed.

[0054] The continuous line shown includes firstly a winding installation 1 of a coil 2 of a long product 3 of hot-rolled stainless steel.

[0055] The long product 3 is, for example, a ribbon or a thread.

[0056] For example, a ribbon has a width between 1 and 8 mm and a thickness between 0.1 and 3 mm.

[0057] For example, a wire has a diameter between 1 and 14 mm.

[0058] The long product 3, in particular wire or ribbon, has for example a mass between 10 kg and 1000 kg.

[0059] The long product 3 has on its surface a layer of oxides with a thickness generally between 0.2 and 30 µm.

[0060] The long product 3 is scrolled at a speed typically up to 15 m / s.

[0061] Depending on the method of implementation of the Figure 1 The processing unit 5 is located on the line downstream of the unwinding unit 1, and upstream of a wire drawing unit 6. In this embodiment, the unwinding unit 1, the processing unit 5, and the wire drawing unit 6 are arranged on a continuous line.

[0062] The treatment installation 5 includes a stripping unit 7 and a control unit 9.

[0063] The stripping assembly 7 is intended to treat the surface of the long product 3 in order to strip the oxide layer on the surface of the long product 3, to ablate a layer of metal of predetermined thickness on the surface of the long product 3, and so as to obtain a predetermined roughness on the surface of the long product 3. The stripping assembly 7 is in particular configured to treat the surface of the long product 3 homogeneously, so that the surface condition of the long product 3 is homogeneous over the entire surface.

[0064] Stripping set 7 is designed to strip the oxide layer by ablation, sublimation or vaporization of the oxides.

[0065] The metal layer to be ablated is located beneath the oxide layer. Ablation of a predetermined thickness of metal layer on the surface of the long product 3 results in a higher quality surface after processing. Indeed, the metal beneath the oxide layer generally contains surface defects, internal oxides, inclusions, and / or areas with a chemical composition different from that of the core metal, which should be removed.

[0066] The thickness of the metal layer to be ablated is typically between 5 µm and 50 µm. For example, for a long product made of nickel 625 alloy, this thickness is between 10 µm and 15 µm.

[0067] Obtaining a predetermined roughness on the surface of the long product 3 optimizes the adhesion of soaps used for wire drawing, and thus provides improved wire drawing performance.

[0068] The desired roughness depends on the metal composition, its dimensions, and the desired wire drawing performance.

[0069] Roughness is assessed by measurement across the long product using a contact probe, according to standard NF EN ISO 4287:1998.

[0070] For example, for low roughness grades (especially type 625), the roughness Ra with a cutoff frequency λc=0.8 mm (or Ra 0.8 ) is less than 1.4 µm.

[0071] For grades with more pronounced topography or relief (notably grade 286), the roughness Ra with a cutoff frequency λc=2.5 mm (or Ra 2.5 ) is less than 6 µm, and generally greater than 1.4 µm.

[0072] The stripping assembly 7 comprises at least one group 11 of a plurality of lasers 13 intended to be distributed around the long product 3 during its movement. The lasers are, for example, centered around an axis, hereinafter referred to as the movement axis A d, intended to correspond to a central axis of the long product during its movement.

[0073] Each laser 13 is intended to treat a portion of the surface of the long product 3. In particular, each portion thus assigned to a given laser 13 is delimited by two straight lines on the surface of the long product parallel to the direction of travel.

[0074] Each portion generally extends along the entire length of the product (3 long).

[0075] In particular, when the long product 3 is a ribbon, the portion allocated to each laser 13 is a predetermined width strip of the product surface (the width then being equal to the distance between the two lines delimiting the portion).

[0076] When the long product 3 is a wire, the portion allocated to each laser 13 is a portion of the surface of the wire 3 delimited by two lines parallel to the direction of scrolling, these two lines forming with the scrolling axis A d a given angle denoted βi.

[0077] The set of portions allocated to the lasers 13 of the same group 11 covers the entire surface of the product. Thus, in the case of a wire, the sum of the angles βi is greater than or equal to 360°.

[0078] Preferably, the sum of the areas of the portions allocated to the lasers 13 of the same group 11 is greater than the surface area of ​​the long product. In this case, each portion allocated to one laser 13 partially overlaps the portion allocated to two other lasers 13. This avoids or minimizes differences in surface finish that might exist between the central area of ​​a portion and the areas located at its periphery, which are likely to receive less laser power than the central area of ​​a portion. The overlap of one portion by another allows the overlapping areas of the two portions concerned, each located at the periphery of its respective portion, to be treated by two lasers 13.

[0079] Preferably, the portions allocated to the lasers 13 are of equal dimensions. For example, when the long product 3 is a wire, the angles βi associated with the lasers of group 11 are equal to each other. For example, with the lasers 13 of group 11 distributed regularly around the wire 3, the angles βi associated with the lasers 13 of group 11 are equal to each other.

[0080] In the illustrated example, the stripping set 7 comprises two groups: a first group 11a of a plurality of first lasers 13 distributed around the long product 3 in motion, and a second group 11b of a plurality of second lasers also distributed around the long product 3 in motion.

[0081] The second lasers of the second group 11b are downstream of the first lasers of the first group 11a with respect to the direction of travel. In particular, each second laser is positioned downstream of all the first lasers with respect to the direction of travel.

[0082] Each group of 11 lasers is intended to treat the surface of the long product.

[0083] According to one embodiment, each group 11 of lasers is intended to treat the entire surface of the long product. In this embodiment, the entire surface of the long product is intended to be treated successively by the lasers of the first group 11a, then by the lasers of the second group 11b, and where applicable, by the lasers of each additional group.

[0084] Alternatively, at least one group 11 of lasers is intended to treat only a portion of the surface of the long product. In this alternative, the groups 11 of lasers, taken together, are intended to treat the entire surface of the long product.

[0085] Each group 11, 11a, 11b of lasers comprises at least three lasers 13. In one embodiment, the laser groups comprise the same number of lasers. Alternatively, the number of lasers 13 varies from one group to another.

[0086] Each laser 13 is intended to emit laser beams along a principal emission direction denoted D 1 ,...D i ...D n , where n is the number of lasers 13 in a group 11, 11a, 11b.

[0087] If the long product 3 is a wire, the principal emission directions D 1 ,...D i ...D n are all oriented towards the center of the wire, i.e. the winding axis A d .

[0088] Preferably, within each group 11, 11a, 11b, the lasers 13 are equidistant from the scroll axis A d of the wire 3.

[0089] For example, the group or each group 11, 11a, 11b of lasers consists of lasers 13 distributed around the circumference of the same circle whose center lies on the scroll axis A d . The principal emission directions D 1 ,...D i ...D n are then concurrent and intersect on the scroll axis A d .

[0090] Alternatively, the lasers 13 of the same group 11, 11a, 11b are not distributed around the circumference of a circle, but around the circumference of at least two circles centered on the scroll axis A d or around the circumference of a circular helix, whose helix axis is the scroll axis A d.

[0091] Preferably, the areas of the surface portions intended to be treated by the different lasers 13 of a group 11, 11a, 11b are identical.

[0092] In one embodiment, the areas of the surface portions intended to be treated by each laser 13 of a group are equal from one group to another. Alternatively, the areas of the surface portions intended to be treated by each laser 13 of a group vary from one group to another.

[0093] The 13 lasers are preferably evenly distributed around the long product.

[0094] For example, the lasers are distributed in such a way that the principal emission direction of each laser in group 11, 11a, 11b forms a non-zero angle, called the separation angle α, with the principal emission directions of two other lasers in group 11, 11a, 11b, this angle α being the same regardless of the laser considered within a group 11.

[0095] In this case, and in the case of a wire, the angle α is less than or equal to the angle β formed by the two lines delimiting the portion allocated to each laser 13 with the scroll axis A d . When the angle α is less than the angle β, the portions partially overlap each other.

[0096] Specifically, if the number of lasers in group 11, 11a, 11b is equal to three, this angle α is equal to 120°. If the number of lasers in group 11, 11a, 11b is equal to six, this angle α is equal to 60°.

[0097] According to one embodiment, the spacing angles α are equal from one group to another.

[0098] Alternatively, the separation angle α of the lasers in one group 11a, 11b is different from the separation angle α of the lasers in at least one other group 11b, 11a.

[0099] Furthermore, according to one embodiment, the lasers 13 of the different groups 11a, 11b are not aligned with each other along a direction parallel to the scroll axis A d. For example, in the case of two groups 11a, 11b, the lasers of the first group 11a are not aligned with the lasers 13 of the second group 11b along a direction parallel to the scroll axis A d. Thus, the principal emission direction of each laser 13 of the first group 11a forms a non-zero angle, called the phase angle, with the principal emission direction of a laser of the second group 11a 11b, this phase angle being less than the separation angle α of the lasers of the first and second groups.

[0100] For example, if the separation angles of the lasers in the first and second groups 11a, 11b are identical, the phase angle is equal to half the separation angle.

[0101] Such a phase shift makes it possible to avoid a given area of ​​the surface of the long product 3 being located in the central area of ​​the portion attributed to a laser 13 of the first group 11a and in the central area of ​​the portion attributed to a laser 13 of the second group 11b, or conversely in a peripheral area of ​​these two portions, and thus to obtain a more homogeneous quality surface.

[0102] In the example shown on the Figure 2 , the group 11 of lasers comprises six lasers, distributed uniformly around a wire 3, and are distributed around the same circle whose center is the scroll axis A d . The principal emission direction D i of each laser 13 then forms with the principal emission directions D i-1 , D i+1 of two other lasers 13 of this group 11 a fixed angle of 60°.

[0103] The lasers 13 of the same group 11, 11a, 11b are preferably identical. The lasers 13 are preferably lasers operating in the near-infrared, that is to say with a wavelength between 1000 and 1100 nm.

[0104] Lasers 13, for example, are fiber lasers.

[0105] Lasers 13 are preferably suited to selectively emit continuous or pulsed beams. Pulsed beams, for example, have a pulse duration on the order of nanoseconds, microseconds, or milliseconds.

[0106] Lasers 13 include, for example, Nd:YAG lasers and / or YLS lasers.

[0107] When the stripping assembly 7 includes two groups 11a, 11b of lasers, the first group 11a of lasers is for example intended to strip the oxide layer on the surface of the long product 3 by ablation at least part of a metal layer of predetermined thickness on the surface of the long product 3, and the second group 11b of lasers is intended to finalize the ablation of the metal layer of predetermined thickness while giving the surface of the long product 3 the predetermined roughness.

[0108] In this case, the lasers of the first group 11a preferably operate in a different mode from the mode of the lasers of the second group 11b. Indeed, the lasers of the first group 11a are then configured so as to efficiently remove the oxide layer, and optionally partially adjust the roughness on the surface of the cleaned wire, and the lasers of the second group 11b are configured so as to adjust the roughness on the surface of the cleaned wire, while possibly finishing the cleaning.

[0109] For example, the lasers in the first group 11a are YLS lasers configured to operate in continuous mode, while the lasers in the second group 11b are Nd:YAG lasers configured to operate in pulsed mode, notably with a pulse duration on the order of nanoseconds.

[0110] Alternatively, the lasers in groups 11a and 11b are identical. For example, the lasers in groups 11a and 11b are pulsed lasers, such as Nd:YAG lasers, or continuous-wave lasers, such as YLS lasers. In this case, the lasers in group 1 are preferably configured with different operating parameters, for example, in terms of intensity or frequency, than the lasers in group 2.

[0111] The stripping assembly 7 preferably includes a mechanical or optical distribution system enabling each laser 13 to cover the portion of the surface of the long product allocated to that laser.

[0112] In particular, the distribution system is intended to shape the laser beams emitted by the lasers 13 of each group and / or to move these laser beams over the surface of the long product 3, so that the laser beams emitted by the lasers of each group cover the entire surface of the long product 3 as it moves.

[0113] For example, in the case of a wire, the distribution system is configured so that the angles β i associated with the different lasers 13 of a group 11, 11a and 11b are such that the whole surface of the wire 3 is covered by the lasers, which implies that the sum of the angles β i is greater than or equal to 360°.

[0114] In particular, the distribution system is intended to shape the laser beams emitted by the lasers of each group 11, 11a, 11b, and / or to generate a scan of the surface of the long product 3 by the laser beams, such that the laser beams emitted by each laser cover the portion allocated to that laser.

[0115] The distribution system is for example an optical system 15, configured to shape the beams from each laser 13 in such a way that these beams, once shaped, cover the portion allocated to that laser 13.

[0116] Such a system includes, for example, for each laser 13, an optical device 15 ( Figure 2) configured to transform the spots of the beams emitted by the laser 13 into bands orthogonal to the direction of scrolling of the long product 3. The bands are then of equal length to the width of the portion allocated to each laser (i.e. the distance between the two lines of the surface of the long product which delimit the portion).

[0117] The width of each band, in the direction of travel, varies depending on the speed of the wire. It is between 20 µm and 200 µm, and typically around 50 µm.

[0118] In this way, the entire surface of the long product 3 can be treated by a limited number of lasers 13.

[0119] Each optical device includes, for example, lenses, spherical mirrors and / or cylindrical mirrors designed to adjust the shape and dimensions of the laser beam.

[0120] In this embodiment, the lasers 13 are preferably high average power or high pulse power lasers, so as to maintain a sufficiently high energy density over the entire portion associated with each laser.

[0121] Alternatively, the distribution system is an optical and mechanical scanning system.

[0122] Such a scanning system includes, for example, for each laser 13, an optical and mechanical device designed to shape the beams generated by the laser 13 in order to concentrate its power, and to move the beams thus shaped over the surface of the long product 3 in motion so that the beams impact the entire portion allocated to the laser 13.

[0123] In particular, the optical and mechanical device is designed to move the beams generated by the laser 13 onto the surface of the long product 3, so that each laser can impact the portion of the surface allocated to the laser.

[0124] For example, the optical and mechanical device is configured to move the beams along first and second scanning directions orthogonal to each other, specifically along several successive parallel lines. The scanning is thus performed, for each line, along the first direction, and to move from one line to the next along the second direction.

[0125] The first and second scanning directions form an angle between 0° and 90° with the scroll axis. For example, these directions are respectively parallel and orthogonal to the scroll axis, or respectively orthogonal and parallel to the scroll axis, or each form a non-zero angle, for example of approximately 45°, with the scroll axis.

[0126] The optical and mechanical device is configured to generate such a scan at a scan speed and scan step adapted according to the desired processing, as described below.

[0127] For example, the beams from each laser 13 scan the portion associated with that laser along lines parallel to the first scanning direction, the lines being offset from each other according to the chosen scanning step.

[0128] Such an optical and mechanical system includes, for example, at least one galvanometric mirror and may also contain a polygonal wheel.

[0129] This embodiment does not require the use of lasers with such high power as in the case of optical system 15, since the size of the impact of each beam generated by the laser is small.

[0130] Preferably, the stripping assembly 7 comprises an enclosure 17, inside which are housed the group(s) 11, 11a, 11b of lasers 13 and the distribution system. The enclosure 17 naturally includes two openings on two opposite walls to allow the long product 3 to pass through the enclosure 17. The enclosure 17 is, for example, made of stainless steel.

[0131] The use of such an enclosure 17 makes it possible to protect external elements as well as operators from laser radiation.

[0132] Preferably, the walls of enclosure 17 are equipped with active and / or passive safety systems that shut down the lasers in case of problems (for example, in case of overheating or perforation of the enclosure). For example, the enclosure has a double wall containing a fluid whose pressure or level is continuously measured.

[0133] In addition, cameras are preferably installed inside the enclosure to monitor the proper progress of the treatment.

[0134] The control unit 9 is intended to control the stripping assembly 7 to impose operating parameters enabling the stripping of the entire oxide layer over the entire surface of the long product 3, the removal of a layer of metal on the surface of the long product 3, this layer of metal being of predetermined thickness, and to obtain a predetermined roughness on the surface of the long product 3 at the end of the treatment.

[0135] The control unit 9 includes, in particular, a memory, a computer and a human / machine interface.

[0136] The piloting unit 9 is specifically designed to acquire information relating to the long product 3 in scrolling.

[0137] This information includes, in particular, the speed at which the long product 3 travels through the processing unit 5. Knowing this speed is essential for adjusting the operating parameters of the stripping unit 7 so that each point on the wire surface is exposed to laser radiation for the appropriate duration.

[0138] This information also includes at least one characteristic dimension of the long product 3 in a plane transverse to the direction of travel of the long product 3. This dimension is, for example, if it is a wire, the diameter of that wire. If the long product is a ribbon, the characteristic dimensions are, for example, the width and thickness of the ribbon. This dimension, or these dimensions, make it possible to determine the extent of the surface to be treated and to focus the laser beams emitted by the stripping assembly 7 precisely onto the surface to be treated.

[0139] This information preferably includes the position of the scroll axis Ad in a plane orthogonal to that axis. Indeed, it may happen that the scroll axis Ad changes position in a plane orthogonal to this axis Ad, which may require, in order to guarantee the desired surface finish, modifying the focusing of the lasers 13 and / or the distribution of the laser beams.

[0140] Information acquired by the control unit 9 is, for example, entered by an operator via the control unit 9 interface and recorded in memory.

[0141] Alternatively or in addition, the processing installation 5 is equipped with a determination system, in particular for measuring the speed of movement of the long product 3 and / or a system for determining or measuring the position of the long product 3 within the stripping assembly 7, in particular the position of the movement axis A d . In this case, the information relating to the moving long product is provided to the control unit in real time by the determination system(s).

[0142] The pilot unit 9 is also configured to acquire desired processing parameters for the long product 3 to be processed.

[0143] These processing parameters include, in particular, a desired roughness for the long product 3 at the end of the treatment.

[0144] These processing parameters preferably include parameters relating to the oxide layer to be ablated and / or a thickness of the metal layer that one wishes to ablate on the surface of the long product 3.

[0145] The processing parameters are, for example, entered by an operator via the interface of the control unit 9, and recorded on the memory of the control unit 9, or entered automatically depending on the product to be processed.

[0146] Alternatively, or in addition, at least some of these processing parameters, in particular the desired roughness for the long product 3 at the end of the processing, are provided by the installation 6 ensuring the wire drawing, which allows the surface condition of the wire to be adjusted in real time to facilitate wire drawing.

[0147] The control unit 9 is configured to determine operating parameters to be imposed on the stripping assembly 7, in particular on the lasers of group(s) 11, 11a, 11b of lasers to obtain the stripping of the oxide layer on the surface of the long product 3, to ablate the metal layer of predetermined thickness on the surface of the long product, and to obtain the predetermined roughness on the surface of the long product 3. The predetermined metal layer thickness and roughness are parameters previously acquired by the control unit 9, as described above.

[0148] To this end, the control unit 9 is designed to record reference experimental data in memory, enabling the computer to determine, based on the desired processing parameters and information relating to the long product in motion, the operating parameters to be imposed on the stripping assembly 7.

[0149] These operating parameters include, for example, the emission power of the lasers 13, the operating mode of the lasers 13 (continuous or pulsed beams), and the laser / matter interaction time (corresponding to the duration for which a laser beam impacts the surface of the product).

[0150] Indeed, regardless of the scanning speed, each portion of the surface must have been treated and must have received the required energy density, as determined by the control unit 9. This energy density will depend on the laser / matter interaction time and the power density of the laser beam.

[0151] For a laser in continuous mode, the laser / matter interaction time, which depends on the scanning speed, depends on the settings of the distribution system. For example, if the distribution system includes, at least for some lasers 13, an optical device 15, the laser / matter interaction time is adjusted by varying the width of the bands formed by the optical device 15 from the laser spots.

[0152] If the distribution system includes, at least for some lasers 13, a scanning system, the laser / matter interaction time is set by varying the scanning speed and the scanning step.

[0153] For a laser in pulsed mode, as for a laser in continuous mode, the laser / matter interaction time, which depends on the scan speed, is determined by the settings of the distribution system. For example, if the distribution system includes, at least for some lasers 13, an optical device 15, the laser / matter interaction time is adjusted by varying the width of the bands formed by the optical device 15 from the laser spots. If the distribution system includes, at least for some lasers 13, a scanning system, the laser / matter interaction time is adjusted by varying the scanning speed and the scanning pitch.

[0154] For a laser in pulsed mode, the laser / matter interaction time is further adjusted by varying the duration and pulse frequency of the pulsed beams.

[0155] Thus, the operating parameters include, depending on the case, the width of the bands formed by the optical device 15, the speed and the scan step, and / or the duration and pulse frequency of the pulsed beams.

[0156] For example, the emission power of the lasers 13 is chosen to be greater the higher the speed of the long product 3 is and / or the greater the thickness of the layer of metal to be ablated.

[0157] Furthermore, the higher the scroll speed, the higher the pulse frequency must be, to ensure that a given portion is adequately processed by the laser 13 that concerns it.

[0158] Furthermore, the scanning speed is chosen to be higher the higher the scrolling speed of the long product.

[0159] In general, if the thickness of the metal layer to be ablated is small, a high scroll speed will be chosen, thus using a high scanning speed.

[0160] The operating parameters are also, as described above, selected to obtain a predetermined surface roughness.

[0161] The desired roughness is obtained for example by adapting the operating mode of the lasers 13, for example by selecting the pulsed mode, and by adapting the duration of laser / matter interaction on the surface of the long product so that the laser impacts generate on the surface of the long product 3 craters of dimensions and spacing or overlap giving the surface the desired roughness.

[0162] When the distribution system is an optical and mechanical scanning system, the roughness is adjusted, for example, by selecting the scanning pitch according to the width of the laser beam.

[0163] For example, if the beam width is 75 µm, the beams from each laser scan the area along lines also 75 µm wide, forming grooves of that width. If the scan spacing is chosen to be less than or equal to 75 µm, for example 25 µm, the scanning of the area will generate a surface with very low roughness. Conversely, if the scan spacing is chosen to be greater than the beam width, for example 100 µm, ridges will remain between each groove, giving the product surface a higher roughness.

[0164] The operating parameters of lasers in the same group 11, 11a, 11b are generally identical to each other. This is particularly the case if the surface portions treated by these lasers 13 are of identical dimensions, the lasers being located at the same distance from the portion to be treated.

[0165] On the other hand, when the stripping set 7 includes two or more groups, the operating parameters generally differ from one group to another.

[0166] In particular, the stripping set 7 comprising two groups, the operating parameters of the lasers of the first group 11a are preferably selected so as to efficiently strip the oxide layer, while the operating parameters of the lasers of the second group 11b are selected so as to give the surface of the stripped long product the desired roughness.

[0167] For example, the lasers in the first group 11a are configured to operate in continuous mode, with the laser power selected to strip the entire oxide layer, and the lasers in the second group 11b are configured in pulsed mode, with the pulse duration and, where appropriate, the scan step chosen so that the impacts of these pulses generate the desired roughness on the surface of the long product 3.

[0168] The control unit 9 is capable of controlling the stripping assembly 7 according to the operating parameters thus determined.

[0169] The control unit 9 is configured to determine the operating parameters before any stripping, and preferably during processing, particularly following the detection of a change in one or more parameters relating to the long product in motion or the desired processing parameters.

[0170] For example, if the scroll speed is determined continuously or at certain times by a scroll speed determination system and provided to the control unit 9, the control unit 9 is configured to determine new operating parameters in case of a change in scroll speed, and to apply these new operating parameters to the stripping assembly 7.

[0171] Furthermore, if the position of the scroll axis A d is determined continuously or at certain times, by a system for determining this position, and provided to the control unit 9, the control unit 9 is configured to determine new operating parameters in case of a change in this position, and to apply these new operating parameters to the stripping assembly 7.

[0172] In another example, if the long product is drawn directly from the outlet of the pickling assembly 7, and its drawability proves insufficient, the desired roughness can be modified to increase the drawability. The control unit 9 is configured to receive the new desired roughness, to determine new operating parameters adapted to obtain the new roughness, and to apply these new operating parameters to the pickling assembly 7.

[0173] We will now describe a process for treating a long product 3 according to one embodiment. The treatment process is preferably implemented using a treatment plant 5 as described above.

[0174] In this example, we will consider an installation 5 in which the stripping assembly 7 comprises two groups of lasers one after the other in the direction of product movement.

[0175] We will also consider that the long product 3 is a wire, and that each group 11a, 11b of lasers comprises six lasers 13 uniformly distributed around the wire 3, and located on the circumference of a circle whose center is occupied by the center of the wire 3.

[0176] Each laser 13 of each group 11a, 11b is thus intended to treat a portion of the surface of the wire extending between two straight lines parallel to the scroll axis A d of the wire 3 and defining with this axis an angle β of at least 60°.

[0177] This treatment process is implemented for example after an annealing treatment carried out on the long product 3 in the form of a crown.

[0178] The treatment process is carried out on the long product 3 in scrolling, following its unwinding.

[0179] The process includes an acquisition step, by the control unit 9, of parameters or information relating to the long product in scroll and desired processing parameters.

[0180] As described above, the parameters relating to the long product in motion include the nature of the long product 3 (e.g. wire or ribbon), the speed of motion of the long product 3 in the processing installation 5 and / or a characteristic dimension of the long product 3 in a plane transverse to the direction of motion of the long product 3. This information is entered for example by an operator via the interface of the control unit 9, or entered automatically when the long product 3 is loaded into the installation, and stored in memory.

[0181] Alternatively or in addition, information relating to the long product in motion is determined by a system for detecting the speed of motion of the long product 3 and / or a system for detecting the position of the long product 3 within the stripping assembly.

[0182] The desired processing parameters for long product 3 include the desired roughness for long product 3 after processing, and preferably parameters relating to the oxide layer to be ablated and / or the thickness of the metal layer to be ablated on the surface of long product 3.

[0183] The processing parameters are, for example, entered by an operator via the interface of the control unit 9, and recorded in the memory of the control unit 9.

[0184] The process then includes a step of determining, by the control unit 9, operating parameters to be imposed on the lasers of the group(s) 11, 11a, 11b of lasers to obtain the removal of the oxide layer on the surface of the long product 3, to ablate the metal layer of predetermined thickness on the surface of the long product, and to obtain the predetermined roughness on the surface of the long product 3.

[0185] These operating parameters are determined from reference experimental data recorded in the memory of the control unit 9.

[0186] These operating parameters include, for example, the emission power of the lasers 13, the operating mode of the lasers 13 (continuous or pulsed beams), and, where applicable, the duration and pulse frequency of the pulsed beams.

[0187] If the distribution system is an optical and mechanical scanning system, the operating parameters include, for each laser 13, scanning parameters of the portion allocated to the laser 13 by that laser, including the scanning speed and the scanning step.

[0188] The control unit 9 then transmits the operating parameters thus determined to the stripping assembly 7.

[0189] The stripping assembly 7 then treats the surface of the long product 3 according to these operating parameters.

[0190] In particular, each laser 13 emits laser beams in the chosen operating mode, and with the power controlled by the control unit 9.

[0191] If the operating mode of the lasers 13 of at least one group 11, 11a, 11b is pulsed mode, each laser 13 emits laser pulses whose duration and frequency are those controlled by the control unit 9.

[0192] Furthermore, if the laser distribution system 13 of at least one of the groups 11, 11a, 11b is a scanning system, this scanning system generates a scan of the laser beams emitted by each laser according to the scanning speed and the scanning step controlled by the control unit 9.

[0193] During the passage of the long product 3 in the stripping assembly 7, each laser 13 of each group 11, 11a, 11b emits laser beams to treat the portion of the product surface allocated to it, according to the operating parameters imposed by the control unit 9.

[0194] Since the long product 3 is in motion, the portion treated by each laser 13 at the end of the treatment extends over the entire length of the long product 3 in the direction of motion (different successive sections of each portion moving past the stripping assembly).

[0195] If the stripping assembly includes a first group of first lasers and a second group of second lasers, the surface is treated successively by the lasers of the first group and then by the lasers of the second group.

[0196] According to one embodiment, each group 11 of lasers treats the entire surface of the long product. In this embodiment, the entire surface of the long product is treated successively by the lasers of the first group 11a, then by the lasers of the second group 11b, and where applicable, by the lasers of each additional group.

[0197] Alternatively, at least one group 11 of lasers treats only a portion of the surface of the long product. In this variant, the groups 11 of lasers, taken together, treat the entire surface of the long product.

[0198] At the end of the treatment, the long product 3 is free of oxides on its surface. In particular, the long product 3 is free of oxides resulting from the product's exposure to high temperature in an oxidizing atmosphere (especially during annealing).

[0199] In addition, the long product 3 has a characteristic roughness profile, different from that obtained by chemical pickling.

[0200] By roughness profile, we mean the profile derived from the primary profile by removing the long wavelength components, by applying a profile filter λc to remove the components with wavelengths greater than λc (in particular the waviness components), as described in the standard NF EN ISO 4287:1998. In the present case, we will consider the components with wavelengths less than λc=2.5 mm.

[0201] In particular, following pickling in a bath, the long product has a granular surface, and exhibits irregular and non-periodic patterns on its surface.

[0202] On the contrary, the surface of the long product 3 treated according to the invention has a periodic roughness profile, i.e. presents periodic roughness patterns on its surface.

[0203] These roughness patterns form profile elements on the roughness profile (as defined in standard NF EN ISO 4287:1998).

[0204] As specified in the standard NF EN ISO 4287:1998, the roughness profile is determined from a surface profile resulting from the intersection of the actual surface with a given cutting plane, one of whose normals is parallel to the actual surface and of appropriate direction.

[0205] The width of the periodic patterns is between 5 µm and 1 mm, and for example between 5 µm and 200 µm.

[0206] For example, the patterns are periodic striations, comprising a regular alternation of raised lines (or ridges) and furrows.

[0207] The grooves correspond to the areas of the surface of the long product 3 which received the highest energy density from the lasers 13, while the raised lines are the areas of the surface of the long product 3 which received the lowest energy density from the lasers 13.

[0208] The furrows and lines extend for example in a direction parallel to the central axis of the long product 3, in a direction orthogonal to the central axis of the long product 3, or in a direction oblique to the central axis of the long product (in particular forming an angle of 45° with the central axis).

[0209] For example, if the distribution system is an optical and mechanical scanning system, the orientation direction of the lines and grooves corresponds to the scanning direction of the laser beams (i.e., the first scanning direction defined above). The distance between grooves (i.e., along the second scanning direction) is then equal to the scanning pitch.

[0210] Referring to the example above, if the beam width is 75 µm and the scan pitch is 100 µm, the grooves will have a width of approximately 75 µm while the raised lines (or ridges) will have a width of approximately 25 µm.

[0211] In general, the intergroove distance (corresponding to the width of the periodic patterns) is between 5 µm and 1 mm, and for example between 5 µm and 200 µm. By intergroove distance we mean of course the distance between each groove and an adjacent groove.

[0212] Alternatively, the periodic patterns are formed by a regular alternation of peaks and troughs along a first and second distinct directions.

[0213] The first and second directions are, for example, orthogonal to each other, in particular respectively parallel to the central axis of the long product 3 and orthogonal to the central axis.

[0214] According to another example, at least one of the first and second directions is neither parallel nor orthogonal to the central axis of the long product 3. In all cases, the periodic patterns will be visualized, on the roughness profile, as periodic profile elements each consisting of a peak and a trough.

[0215] The height of profile features, for example the average height between crests and furrows, or the average height between peaks and troughs, is generally between 0.2 µm and 500 µm.

[0216] To measure the distance between the profile elements and their height, as explained above, an appropriate cutting plane will be chosen, for example by visualizing the surface of the product beforehand by imaging, in particular by optical microscopy, scanning electron microscopy, or by means of a roughness tester.

[0217] For example, if the periodic patterns are grooves and raised lines parallel to the central axis of the long product 3, a cutting plane orthogonal to the central axis will be chosen. Conversely, if the lines and grooves are orthogonal to the central axis of the long product 3, a cutting plane parallel to the central axis will be chosen.

[0218] If the periodic patterns are alternating peaks and troughs along a first and a second direction, preferably two planes of section parallel to the first and second directions respectively will be chosen, and the average width and height will be evaluated in each of these directions.

[0219] Preferably, the waste generated by the oxide stripping and metal removal by stripping assembly 7 is recovered by dust and fume extraction systems.

[0220] Preferably, during processing, the operating parameters are recalculated by the control unit 9 in case of modification of parameters relating to the long scrolling product, or of the desired processing parameters.

[0221] For example, if the scroll speed is determined continuously or at certain times by a scroll speed determination system and provided to the control unit 9, a change in the scroll speed results in the calculation of new operating parameters, adapted to the new scroll speed, and these new operating parameters are applied to the stripping assembly 7.

[0222] Furthermore, if the position of the scroll axis A d is determined continuously or at certain times, by a system for determining this position, and provided to the control unit 9, the control unit 9 will determine new operating parameters in case of a change in this position, and apply these new operating parameters to the stripping assembly 7.

[0223] In another example, if the long product is drawn directly from the outlet of the pickling unit 7, and its drawability proves insufficient, the desired roughness can be modified to increase the drawability. This new roughness is provided to the control unit 9, triggering the calculation of new operating parameters adapted to achieve the new roughness, and these new operating parameters are then applied to the pickling unit 7.

[0224] In yet another example, if a laser or lasers in a group malfunction, the operating parameters can be recalculated to take this malfunction into account.

[0225] The installation and process according to the invention thus makes it possible to treat efficiently, quickly and without the use of harmful products, ensuring both the removal of the oxide layer present on the long product, the removal of surface defects, internal oxides, inclusions and / or areas of chemical composition different from that of the core of the metal on the surface of the metal under the oxide layer, and giving the surface of the long product a roughness making it suitable for wire drawing without additional operation.

[0226] Although the installation and process have been described more specifically with reference to a wire, the installation and process are also suitable for processing other types of long products such as ribbons.

[0227] For example, to process a ribbon comprising two main surfaces and two surfaces extending along the thickness of the ribbon, one or more laser groups can be used, comprising at least one laser positioned opposite each main surface, and at least one laser positioned opposite each of the surfaces extending along the thickness of the ribbon.

Claims

1. A facility (5) for the treatment of a metal long product (3) in movement, in preparation for a wire drawing step, the long product (3) having at least one surface covered with a layer of oxides, said facility comprising: - a stripping assembly (7) comprising at least one group (11, 11a, 11b) of a plurality of lasers (13) distributed around the moving long product (3), each laser (13) being configured to emit beams onto the surface of the moving long product (3) for stripping the surface, each laser (13) being intended for the treatment of an associated portion of the surface of the long product (3), - a control unit (9) configured to acquire information relating to the long product (3) in movement, the information comprising a speed of movement of the long product (3) and at least one characteristic dimension of the long product (3) in a plane orthogonal to an axis of movement (Ad) of the long product, characterized in that the control unit (9) is configured to: - determine the operating parameters to be imposed on the stripping assembly (7) for obtaining the stripping of the layer of oxide on the surface of the long product (3) and to ablate a layer of metal of predetermined thickness on the surface of the long product (3), and so as to obtain on the surface of the long product periodic roughness patterns, the width of the periodic patterns being comprised between 5 µm and 1 mm, compared with experimental results pre-recorded in the control unit (9), and - impose said operating parameters to said stripping assembly (7).

2. The treatment facility (5) according to claim 1, characterized in that the lasers (13) of the or each laser group (11, 11a, 11b) are uniformly distributed around the moving long product (3).

3. The treatment facility (5) according to any of claims 1 or 2, wherein the operating parameters include an emission power of the lasers (13) of the or each group (11, 11a, 11b) and / or a laser / material interaction time at each point on the surface of the long product (3).

4. The treatment facility (5) according to any of claims 1 to 3, wherein the stripping assembly (7) comprises a distribution system configured to shape the laser beams or to move the laser beams across the surface of the long product (3) such that the laser beams emitted by the plurality of lasers (13) in the or each group (11, 11a, 11b) cover the entire surface of the long product (3) during the movement thereof.

5. The treatment facility (5) according to claim 4, wherein the distribution system comprises, for each laser (13) of at least one group (11, 11a, 11b), an optical device (15) configured to transform each beam emitted by the associated laser (13) into a band affecting a portion of the surface of the long product (3).

6. The treatment facility (5) according to claim 4 or 5, wherein the distribution system comprises, for each laser (13) in at least one group (11, 11a, 11b), a scanning device configured to move the beams generated by the associated laser (13) across the surface of the long product (3), according to a predetermined scan speed and scan pitch, so that the beams emitted by each laser (13) affect a portion of surface of the long product (3).

7. The treatment facility (5) according to claim 6, wherein the operating parameters comprise the scan speed and the scan pitch of the scanning device.

8. A treatment facility (5) according to any of claims 5 to 7, wherein the portion of surface of the long product (3) is defined by two straight lines, parallel to each other, of the surface of the long product (3).

9. The treatment facility (5) according to any of claims 1 to 8, wherein the stripping assembly (7) comprises a first group (11a) of a plurality of first lasers distributed around the moving long product (3) and a second group (11b) of a plurality of second lasers distributed around the moving long product (3), each second laser being downstream of each first laser of the first group (11a) with respect to the axis of movement (Ad).

10. The treatment facility (5) according to claim 9, wherein the first lasers are configured to strip the layer of oxide on the surface of the long product (3) by ablating a layer of metal of predetermined thickness on the surface of the long product (3), and the second lasers are configured to impart the predetermined roughness to the surface of the long product (3).

11. The treatment facility (5) according to any of claims 9 or 10, wherein the first lasers are continuous emission lasers, and the second lasers are continuous emission lasers or lasers configured to emit pulsed beams, in particular nanosecond lasers.

12. A treatment method, by means of a facility (5) according to any of claims 1 to 11, for a moving metal long product (3), in preparation for a wire drawing step, the long product (3) having at least one surface covered with a layer of oxides, comprising the following steps: - acquisition by the control unit (9) of information relating to the long product (3) in movement, the information comprising a speed of movement of the long product (3) and at least one characteristic dimension of the long product (3) in a plane transverse to an axis of movement (Ad) of the long product (3), - determination by the control unit (9), according to the information relating to the long product (3) in movement, of the operating parameters to be imposed on the stripping assembly (7) for obtaining the stripping of the layer of oxide on the surface of the long product (3) and to ablate a layer of metal of predetermined thickness on the surface of the long product (3), and so as to obtain a on the surface of the long product (3) periodic roughness patterns, the width of the periodic patterns being comprised between 5 µm and 1 mm, by comparison with experimental results pre-recorded in the control unit (9), - control by the control unit (9) of the stripping assembly (7) to impose said operating parameters on the stripping assembly (7), - emission by the stripping assembly (7), by means of lasers (13), of laser beams on the surface of the moving long product (3) according to the operating parameters determined by the control unit (9).

13. A metal long product (3) for wire drawing, characterized in that the long product (3) having periodic roughness patterns on the surface thereof, the width of the periodic patterns being comprised between 5 µm and 200 µm.

14. A metal long product (3) according to claim 13, wherein the periodic patterns consist of periodic striations, comprising a regular alternation of protruding lines and grooves, or in patterns comprising a regular alternation of peaks and recesses along a first and a second distinct directions.

15. The metal long product (3) according to claim 14, wherein the average height between the ridges and grooves, or the average height between the peaks and recesses, is comprised between 0.2 µm and 500 µm.

16. The long product (3) according to any of claims 13 to 15, characterized in that the long product (3) is a wire or a ribbon.