Method and device to control the geometrical parameters of a coated wire

Abstract

The present invention relates to an apparatus (100) for applying a layer of coating material (2) to a wire (1), said apparatus (100) comprising: - a coating chamber (110) for applying a coating material (2) to a wire (1) passing through the coating chamber (110), wherein the coating chamber (110) comprises an inlet opening (111) configured for receiving the wire (1) and an outlet opening (112) configured for releasing the wire (1), said inlet opening (111) and said outlet opening (112) being configured to allow the wire (1) to follow a plurality of trajectories across said coating chamber (110); - an elongate injection channel (120) comprising an opening (125) for receiving a predetermined quantity of coating material (2), said elongate injection channel (120) being configured to be in communication with the coating chamber (110); - at least one heating system (130) configured to raise the temperature of the coating material (2) as the coating material (2) flows through the injection channel (120); - a wire positioning device (150) configured to position the wire (1) according to a trajectory across the coating chamber (110), wherein said trajectory is comprised in said plurality of trajectories.

Description

[0001] METHOD AND DEVICE TO CONTROL THE GEOMETRICAL PARAMETERS OF A COATED WIRE

[0002] DESCRIPTION

[0003] The present invention relates to a coating apparatus of the type capable of applying a layer of coating material on a wire without using any type of solvent (also referred to as “solvent-free coating apparatus” in the rest of the present description). In particular, the present invention relates to a method and a device to allow precise control of the geometrical parameters of the coating layer applied on a wire by a solvent-free coating apparatus.

[0004] An example of a solvent-free coating apparatus for applying a coating material to a wire can be found in the document EP3192081.

[0005] As it will become apparent during the course of the present description, the innovative coating approach adopted by the solvent-free coating apparatus described in patent EP3192081 leverages on a coating principle (also referred to as hydrodynamic coating in the rest of the present description) which differs under many respects from known, more conventional coating techniques such as, for example, extrusion coating and enameling coating.

[0006] In wire extrusion coating (also referred to as extrusion, in the course of the present description), a layer of highly pressurized molten material is forced out from an extrusion die and laid around the surface of a moving wire; typically, the wire is pulled at a certain speed and guided through the extrusion die by means of a positioning die which is usually arranged concentrically with respect to the extrusion die. The compound comprising the extrusion die and the positioning die is usually referred to as extrusion crosshead. The extrusion die is usually configured to receive a certain quantity of highly pressurized coating material and to form a layer of coating material fitting on the surface of the wire exiting from the positioning die. Although the shape of the coating layer (i.e., the shape of the external contour of the coating layer), the thickness of the coating layer, and the concentricity of the coating layer applied on the surface of the wire can be directly controlled by properly designing said crosshead die (also called calibration die), extrusion coating inherently presents a number of overwhelming problems. First, as the coating layer is simply formed around the wire, the resulting extruded wires are usually characterized by poor mechanical properties such as, for example, a very low adhesion between the coating layer and the wire. In this regard, it is known in the art to improve adhesion by applying an intermediate layer comprising an adhesive agent between the wire and the coating layer; although feasible, such solution is often not desirable as it increases the complexity and the running cost of the extrusion apparatus. Secondly, as the shape, the thickness, and the concentricity of the extruded coating layer largely depend on the design of the extrusion crosshead, the geometrical properties of the resulting extruded wires cannot be modified nor adjusted dynamically. As a result, a traditional extruder does not allow to control dynamically, nor adjust the geometry of the coating layer extruded on the surface of a running wire during coating operations. Even further, the extrusion crosshead and, in particular, the positioning die is inevitably subjected to mechanical wear thus undermining, on the long run, the uniformity of the geometrical properties of the resulting coated wire while inevitably increasing the maintenance cost of the extrusion apparatus. US patent application US2008 / 0038392A1 discloses a device for extruding a coating material on the surface of a wire comprising two interchangeable extrusion dies characterized by different calibrating sections; in particular, document US2008 / 0038392A1 allows to vary the thickness of the coating layer extruded on a wire by interchanging said two extrusion dies. Beside increasing the complexity of the system, the device disclosed in document US2008 / 0038392A1 does not allow to vary the thickness of the coating layer in a continuous fashion (i.e., only two calibrating diameters can be interchanged); further, the device comprises a mechanical arrangement to guide the wire (i.e., positioning die), thus unavoidably rendering the system subjected to mechanical wear.

[0007] In enameling coating, a coating material is typically applied on a wire by directly dipping it into a certain quantity of coating enamel (e.g., a polymeric enamel, also referred to as varnish in the rest of the present description) contained, for example, into a dedicated enameling vessel. Coating enamels are typically prepared by diluting small quantities of solid-state coating material into one or more solvents; as a consequence, after applying the enamel on the wire, it is usually necessary to remove the excess of solvents from the applied coating layer by heating the wire through, for example, a dedicated furnace. Further, as the enamel or varnish is maintained at a very low density in the enameling vessel, the adhesion achieved between the coating material and the surface of the wire typically leverages exclusively on microscopic bondings. As a result, the maximum coating thickness achievable at each step of the enameling coating process is at least one order of magnitude lower than the thickness achievable by the “solvent-free” coating apparatus described in the aforementioned document EP3192081. More importantly, as the viscosity and the density of the coating material is maintained at very low values, it is often very challenging to uniformly retain the layer of coating material laid around the wire during the enameling process; for example, in order to minimize the gravity dripping of the liquid coating material applied on the surface of the wire, the enameling coating process along with the drying procedures are usually held in a vertical fashion thus increasing the complexity and the space requirements of the manufacturing plant. For at least the reasons explained above, the surface of the coating layer applied on the wire by means of enameling coating may comprise unwanted irregularities (e.g., drops, air bubbles, etc.); such imperfections are usually adjusted, at some point of the enameling process, by forcing the enameled wire into a shaping die which is configured to smooth the surface of the enameled wire by mechanically removing any excess of coating material. Further, in order to achieve a predetermined thickness of the coating layer applied around the wire, it is often necessary to deposit multiple layers of coating material on the wire by repeating the whole enameling process multiple times. Another problem related to enameling coating regards the fact that the thickness, the shape, the uniformity, the concentricity, and, in general, the geometry of the coating layer applied around the wire are hardly controllable with a given degree of precision.

[0008] As fully described in the aforementioned document EP3192081, the solvent-free coating apparatus allows to overcome most of the above-described problems in relation to extrusion and enameling coating; specifically, besides allowing to completely avoid the use of any solvent agent, a coated wire created by means of the solvent-free coating apparatus is characterized by optimal mechanical and structural properties (e.g., high adhesion, optimal uniformity of the coating layer, etc.). This is achieved by relying exclusively on the hydrodynamic forces created during the coating process by the coating material contained in a hydrodynamic coating chamber which is maintained at a predetermined temperature and pressure.

[0009] One of the remaining problems still affecting the solvent-free coating apparatus described in the aforementioned document EP3192081 relates to the precise control of the geometrical features of the coating layer laid on the surface of the wire by the solvent-free coating apparatus. In particular, most of the technology fields where coated wires are regularly employed (e.g., in the manufacturing of electric motors and high precision transformers, etc.) require an accurate control of the thickness of the coating layer in at least a plurality of predetermined points along the section of the core wire; more specifically, it is often necessary to have a precise control on the relative position of the core wire with respect to the external surface of the outer coating layer across the entire length of the wire. In general, the shape and the thickness of the coating layer and, consequently, the position of the wire relative to the external surface of the coating layer can be defined by a set of target geometrical parameters characterizing, for example, the thickness of the coating layer in a plurality of predefined points along the cross-section of the core wire. In this regard, although the coating apparatus described in the aforementioned document EP3192081 allows to precisely control the temperature and the viscosity of the coating material along with the pressure exerted on it, it is usually not trivial, if not sometimes impossible, to configure the apparatus in order to apply the coating layer around the wire according to a predetermined set of geometrical parameters defining the shape, the thickness, and the position of the core wire relative to the external surface of the coating layer. This is rendered particularly challenging by the fact that the geometrical parameters of the coating layer applied on the wire by means of a solvent-free coating apparatus are not directly controllable by a shaping die as instead done in traditional coating techniques (e.g., enameling coating, extrusion coating, etc.). In fact, the viscosity and the density of the coating material underlying the hydrodynamic coating process do not usually allow to control the geometrical properties of the coating layer applied on the wire by means of mechanical arrangements such as, for example, a shaping die; in fact, the use of any mechanical arrangement used, for example, to remove the excess of coating material from the surface of the wire would inevitably compromise the uniformity of the coating layer.

[0010] As better explained in the rest of the present description, the geometrical properties of the coating layer applied on a core wire by hydrodynamic coating largely depends on the trajectory followed by the wire across the hydrodynamic coating chamber; due to the chemical nature and the physical properties of most of the coating materials used in the coating industry, the trajectory of the wire across the hydrodynamic coating chamber does not have an easily predictable effect on the final geometrical properties of the coating layer of the wire leaving the hydrodynamic coating chamber. For example, in order to apply a concentric layer of coating material on a round wire (i.e., a layer of coating material characterized by uniform thickness around the surface of the wire) a traditional centering procedure (i.e., centering the wire with respect to an inlet and an outlet opening of the coating chamber and / or centering the wire with respect to the center of the coating chamber) does not always lead to acceptable results. That is, the same predetermined trajectory of the wire through the coating chamber under different operative conditions of the solvent free coating apparatus (i.e., type of coating material, density, viscosity, and pressure of the coating material in the hydrodynamic coating chamber, etc.) may lead to different results in terms of geometrical parameters of the final coating layer. For example, a wire following a trajectory aligned with respect to the center of the hydrodynamic coating chamber (or aligned with the center of an outlet opening of the coating chamber) may sometimes lead to a coated wire characterized by a non- uniform coating layer (i.e., a coating layer non-centered with respect to the core wire).

[0011] More specifically, the control of the geometrical features of the coating layer formed around the wire is rendered particularly challenging by the non-uniformity of the hydrodynamic forces generated by the coating material contained in the coating chamber. That is, despite the careful design of the coating chamber described in patent EP3192081, the hydrodynamic forces acting on the surface of the wire may vary along the length of the coating chamber thus causing, for example, a variable coating effect between the coating material and the surface of the wire; it is worth noting that such phenomenon is mainly due to the non-ideal behavior of the coating material generally used in the wire coating industry (i.e., fluids not following the Newton’s law on viscosity). As the geometrical properties of the coating layer laid on the surface of the wire strongly depends on the distribution of the hydrodynamic forces acting on the wire crossing the coating chamber, it is often extremely challenging to meet with a predetermined set of requirements defining the target geometrical properties of the wire exiting the coating chamber.

[0012] One of the objects of the present invention is to provide an apparatus and a method for coating a wire capable of applying a layer of coating material according to a predetermined set of requirements, whereas said set of requirements defines one or more target geometrical parameters (e.g., one or more thickness parameters in one or more points along the cross-section of the core wire) of said layer of coating material applied on the surface of a wire.

[0013] Another object of the present invention is to provide an apparatus and a method for coating a wire capable of dynamically adjusting the geometrical parameters of the coating layer of the wire exiting the coating apparatus.

[0014] Another object of the present invention is to provide an apparatus and a method for coating a wire capable of applying a layer of coating material characterized by uniform geometrical parameters over the entire length of the wire.

[0015] In view of achieving these objects, the present invention relates to an apparatus for applying a coating material to a wire having all the features indicated in the annexed claim 1. The present invention also relates to a method for applying a coating material to a wire by means of an apparatus according to the present invention. Further, the present invention relates to a method and a device for configuring and / or controlling one or more geometrical parameters of the coating layer applied on a wire by a solvent free coating apparatus. In addition, the present invention relates to a method and a device for configuring and / or controlling the quantity of coating material applied on a wire by a solvent free coating apparatus.

[0016] Further objects, features, and advantages of the present invention will become apparent from the following detailed description and from the annexed drawings, which are supplied by way of nonlimiting explanatory example, wherein:

[0017] Fig. 1 shows a cross-sectioned front view of a preferred embodiment of a coating apparatus according to the present invention;

[0018] Fig. 2 shows a block diagram of a method for controlling the quantity of coating material applied on a wire by a coating apparatus according to the present invention;

[0019] Fig. 3 shows a control unit for controlling one or more geometrical parameters of the coating layer of a coated wire;

[0020] Fig. 4a shows a cross-sectioned front view of a coating chamber of a coating apparatus according to the present invention;

[0021] Fig. 4b shows a cross-sectioned side view of a coating chamber of a coating apparatus according to the present invention;

[0022] Fig. 4c shows a cross-sectioned top view of the coating chamber of a coating apparatus according to the present invention;

[0023] Fig. 5a shows a tridimensional view of a wire positioning system according to an aspect of the present invention;

[0024] Fig. 5b shows a side view of a wire positioning system according to an aspect of the present invention;

[0025] Fig. 5c shows a top view of a wire positioning system according to an aspect of the present invention;

[0026] Fig. 6 shows a block diagram of a method for controlling one or more geometrical parameters of the coating layer applied on a wire by a coating apparatus according to the present invention;

[0027] Fig. 7a, 7b, 7c, and 7d show a cross-section view of a plurality of exemplary rectangular coated wires;

[0028] Fig. 8a and 8b show a cross-section view of exemplary round coated wires; Fig. 9 shows a block diagram of a method for applying a coating material to a wire by means of a coating apparatus according to the present invention.

[0029] In the following description, various specific details are illustrated aiming at a thorough understanding of examples of one or more embodiments of the present invention. The embodiments can be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. The reference to “an embodiment” in the context of this description indicates that a particular configuration, structure or characteristic described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as “in an embodiment”, possibly present in different places of this description do not necessarily refer to the same embodiment. Moreover, particular conformations, structures or characteristics can be combined in a suitable manner in one or more embodiments and / or associated with the embodiments in a different way from that illustrated here, for example, a characteristic here exemplified in relation to a figure may be applied to one or more embodiments exemplified in a different figure.

[0030] The references illustrated here are only for convenience and do not therefore delimit the field of protection or the scope of the embodiments.

[0031] In the rest of the present description, the expression “geometrical parameters” of the coating layer will refer to one or more numerical parameters defining the external shape (e.g., round shape, rectangular shape, etc.) and / or the thickness of the coating layer around the wire; consequently, the geometrical parameters can also define the position of the core wire relative to the external surface of the coating layer. For example, as fully described in the rest of the present invention, the geometrical parameters of the coating layer can comprise the thickness value of the coating layer in a plurality of target points located around the surface of an orthogonal cross-section of the core wire.

[0032] In the annexed Fig. 1, reference 100 generally designates a preferred embodiment of an apparatus for applying a coating material 2 to a wire 1 according to the present invention. The apparatus 100 may be used to apply a coating material 2 to any type of wire 1, avoiding the use of solvents as primary agent for applying a coating layer (designated with reference number 12 in figures from 7a to 8b) to a wire 1 while guaranteeing optimal mechanical and thermal properties of the resulting coated wire 1. The wire 1 may comprise any type of metal, such as copper, aluminum, or steel. Copper and aluminum wires 1 are typically used for electrical applications, such as, for example, windings of an electromagnet, an electric motor stator, etc. The wire 1 may be characterized by any kind of section geometry (e.g., rounded section, rectangular section, etc.). The coating material 2 can be any type of coating material 2; for example, the coating material 2 can comprise a polymeric coating material 2 such as a thermosetting or a thermoplastic polymer as well as a blend of two or more polymers.

[0033] The coating apparatus 100 according to the present invention comprises a coating chamber 110 configured for containing a certain quantity of coating material 2 and for applying said coating material 2 to the wire 1 passing through said coating chamber 110; to this end, the coating chamber 110 comprises an inlet opening 111 configured for receiving the wire 1 and an outlet opening 112 configured for releasing the wire 1. More specifically, the coating chamber 110 has an inlet opening 111 through which the wire 1 can pass and enter the coating chamber 110, and an outlet opening 112 through which the wire 1 can come out from the coating chamber 110 with an outer layer of coating material 2 applied on it. According to an aspect of the present invention, the inlet opening 111 and the outlet opening 112 are configured to allow the wire 1 to follow a plurality of trajectories across the coating chamber 110 (i.e., the path followed by the wire 1 in its motion through the coating chamber 110).

[0034] As better explained in the rest of the present description, when crossing the coating chamber 110, the wire 1 draws a certain quantity of coating material 2 towards the outlet opening 112 of the coating chamber 110 with the result of creating a field of hydrodynamic forces acting directly on the surface of the wire 1; the geometrical properties of the coating layer 12 laid on the wire 1 directly depends on the distribution and the intensity of such hydrodynamic forces along the coating chamber 110. In this regard, the design of the coating chamber 110 can be specifically laid out to improve the effect brought about by such hydrodynamic forces on the surface of the wire 1. For example, as shown in Fig. 1, the coating chamber 110 can comprise a cylindrical central section for receiving the wire 1 and a nozzle in correspondence of the outlet opening 112 characterized by a conical shape and designed to concentrate the hydrodynamic forces on the wire 1 before exiting the coating chamber 110.

[0035] As a result, when entering the coating chamber 110, the wire 1 is first dipped into the coating material 2 contained in the coating chamber 110 and then, after crossing the entire length of the coating chamber 110, the wire 1 is released through the outlet opening 112 with a layer of coating material 2 applied on it; by maintaining the coating material 2 at a predetermined viscosity and density, a surprising coating effect caused by a plurality of phenomena of different nature, both mechanical and chemical, take place between the surface of the moving wire 1 and the coating material 2 contained in the coating chamber 110. More specifically, as the wire 1 moves across the coating chamber 110, the liquid polymer adhering on the surface of the wire 1 is drawn towards the outlet opening 112 of the coating chamber 110 and then out of it with the result of forming a layer of coating material 2 around the exiting wire 1. The friction between the wire 1 and the coating material 2 contained in the coating chamber 110 creates an initial coating layer 12 on the surface of the wire 1 as soon as it enters the coating chamber 110; as the wire 1 proceeds through the coating chamber 110, the hydrodynamic forces generated by the movement of the wire 1 throughout the coating chamber 110 and by the coating material 2 contained in it, generate a mechanical coating effect capable of building up an additional layer of coating material 2 upon said initial layer.

[0036] According to an aspect of the present invention, the coating apparatus 100 is configured to exert a predetermined constant pressure on the coating material 2 contained in an injection channel 120, hereinafter described, and the coating chamber 110 by means, for example, of a dedicated pressurizer 180. Preferably, once a required pressure is reached, the pressurizer 180 does not pressurize the coating material 2 any further, but it can be configured to maintain a constant predetermined pressure on said coating material 2 within the injection channel 120 and the coating chamber 110. Alternatively, in order to exert a predetermined pressure on the coating material 2, the injection channel 120 may be sealed and connected to a pressurized gas bottle (e.g., a gas bottle filled with pressurized inert gas, e.g., argon) by means of a pressure line (not shown in the annexed figures).

[0037] As better explained in the rest of the present description, in order to allow such hydrodynamic forces to build up a uniform layer of coating material 2 on the surface of the wire 1 , it is important that the pressure exerted by the pressurizer 180 is not as such as to force the coating material 2 out of the outlet opening 112 during the coating operations (i.e., when the wire 1 moves through the coating chamber 110). On the contrary, said predetermined pressure must be determined so as to balance the load of the coating material 2 provided to the coating chamber 110; such load balance is achieved when the quantity of coating material 2 injected in the coating chamber 110 is equal to the quantity of coating material 2 drawn out the apparatus 100 by the exiting wire 1 (i.e., the coating material 2 adhering on the surface of the coated wire 1). In particular, in order to guarantee the uniformity of the external surface of the coating layer 12 laid on the wire 1, it is essential that the coating material 2 laid on the wire 1 is allowed to leave the coating chamber 110 without any obstruction; for example, according to an aspect of the present invention the outlet opening 112 can be configured to avoid any direct contact with the surface of the coating layer 12 laid on the wire 1 exiting the coating chamber 110. That is, in order to achieve optimal performances in terms of, for example, coating uniformity and flatness, the minimum diameter of the outlet opening 112 is configured to be larger than the section of the coated wire 1 exiting the coating chamber. In particular, as opposite to traditional coating techniques such as, for example, enameling and extrusion coating, the thickness and the shape of the coating layer 12 laid on the wire 1 are determined by the hydrodynamic forces acting on the surface of the wire 1 (i.e., the geometrical parameters of the coating layer 12 do not depend directly on the profile of the outlet opening 112). The applied coating can comprise any type of coating material 2 such as, for example, thermosetting or thermoplastic polymer materials as well as a blend of two or more polymers. Thermosetting materials enable, in general, higher quality coating and perform better at high temperatures than thermoplastic materials. The specific type of thermosetting or thermoplastic material that is used may depend on the type of metal of which the wire 1 is made and / or the required properties of the coating according to the final application for which the wire 1 is produced. The thermosetting polymers may comprise, for example, any of polyester, epoxypolyester mixture, polyurethane, polyethylenimine, polyamide, polyimide, polyamide-imide, a thermosetting polyvinyl formal compound, epoxy, polyesterimide, Polyvinyl fluoride (PVF), and other materials. The coating material 2 may be a mixture or a blend of any of these polymers as well as with other substances, in particular thermosetting additives. For example, a mixture comprising 60% polyvinyl formal and 40% thermosetting additive, or polyesterimide and amideimide mixture, may be used as coating material 2.

[0038] Thermoplastic polymers can comprise, for example, Perfluoroalkoxy (PFA), polyethylene, Polyether ether ketone (PEEK), Polyether ketone ketone (PEKK), Polyetherimide (PEI), Polyphenylene sulfide (PPS), Fluorinated ethylene propylene (FEP), Ethylene tetrafluoroethylene (ETFE), Polytetrafluoroethylene (PTFE), Polyaryletherketone (PAEK), Polyamide-imides (PAI), Polyvinyl fluoride (PVF).

[0039] With reference to Fig. 1, the apparatus 100 further comprises an elongated injection channel 120 comprising a bottom end 123 and an upper end 124; said elongated injection channel 120 is configured for receiving a predetermined quantity of solid-state coating material 2 at an opening 125 and for supplying the received coating material 2 to the coating chamber 110 which is arranged in communication with the bottom end 123 of the injection channel 120. The injection channel 120 may comprise an elongated hollow body (e.g., a hollow cylinder) made of thermal conductive material (e.g., steel, stainless steel, or Inconel).

[0040] The coating chamber 110 is configured to be in fluid communication with the bottom end 123 of the injection channel 120, for enabling the passage of the coating material 2 from the injection channel 120 to the coating chamber 110 and for allowing smooth propagation of the pressure from the injection channel 120 to the coating chamber 110.

[0041] Prior to being fed into the injection channel 120, the coating material 2 can be in solid-state such as, for example, powder, solid pellets, chips or cartridges or in other solid forms that are generally known for paints and enamels.

[0042] According to an aspect of the present invention, the coating material 2 can be inserted into the injection channel 120 by means of an automated feeding system (not shown in Fig. 1) configured for driving the coating material 2 within the injection channel 120 through an opening 125. Preferably, the opening 125 is provided at a side portion of the injection channel 120.

[0043] According to known technologies, the automated feeding system may comprise a hopper provided for inserting solid-state coating material 2, for example in the form of powder, and a duct connecting the hopper with the opening 125. A screw feeding element can be provided within said duct, for rotating within the duct and driving the coating material 2 through the duct, up to reach the opening 125, thus entering into the injection channel 120.

[0044] Preferably, the coating apparatus 100 may comprise a support casing comprising a plurality of casings (not shown in Fig. 1) rigidly connected to each other. Said support casing (i.e., each of said casings) can be preferably made of heat conductive material, such as metal, in order to ensure that uniform heating of the coating material 2 (in particular due to the heating system 130 hereinafter described) is maintained within the injection channel 120.

[0045] The injection channel 120 may comprise a hollow cylinder (in particular, a metal cylinder) that can be inserted, for example, within one or more of said casings of the apparatus 100.

[0046] According to an embodiment of the present invention, said injection channel 120 may have a substantially cylindrical shape, in particular with a substantially constant diameter along its entire length, thus avoiding bottleneck-like shape portions which could obstacle flowing of the coating material 2. This shape of the injection channel 120 enables achievement of an efficient fluid transmission of the coating material 2 towards the coating chamber 110, simple cleaning and maintenance operations of the injection channel 120.

[0047] In order to achieve a desired viscosity of the coating material 2 in the coating chamber 110, the coating apparatus 100 according to the present invention is configured to progressively heat the coating material 2 as it flows through the injection channel 120. More specifically, the coating apparatus 100 is configured to move the solid-state coating material 2 inserted in the injection channel 120 where the solid-state coating material 2 is progressively heated until reaching a desired viscosity and density.

[0048] To this end, the apparatus 100 according to the present invention further comprises at least one heating system 130 comprising, for example, one or more heating elements; said heating system 130 may be configured to progressively raise the temperature of the coating material 2 as the coating material 2 flows through the injection channel 120, in order to achieve a desired viscosity of the coating material 2 within the coating chamber 110. The heating system 130 can be configured to gradually increase the temperature of the injection channel 120 from the upper end 124 (i.e., lower temperatures) to the bottom end 123 (i.e., higher temperatures). This way, the coating material 2 flowing through the injection channel 120 is heated progressively until reaching a predetermined coating temperature in correspondence of the bottom end 123 of the injection channel 120.

[0049] The coating apparatus 100 according to the present invention may further comprise a system 140 for pre-heating the wire 1 before entering the coating chamber 110 (also referred to as “pre-heating system 140” in the rest of the present description). Regardless the specific coating technology employed, wire pre-heating may often yield some advantageous benefits to the coating process such as (for example) improved adhesion, reduced coating defects, and, in general, enhanced mechanical properties of the final coating.

[0050] The pre-heating system 140 can comprise any kind of heating means configured to heat, at a predetermined temperature (also referred to as “pre-heating temperature” in the rest of the present description), the wire 1 before entering the coating chamber 110. For example, the pre-heating system 140 can comprise one or more heaters capable of operating at variable power and configured to heat the wire 1 at variable pre-heating temperatures as it moves towards the coating chamber 110. Advantageously, the pre-heating system 140 can comprise one or more inline induction wire heaters comprising at least one work coil configured to accommodate and to heat the wire 1 as it moves towards the coating chamber 110; for example, the inline induction wire heaters can be configured to operate with a wire 1 of any section geometry with a diameter between

[0051] 1 and 40 mm, with a variable power supply operating from 1 to 500 kW (also referred to as “preheating power level”) capable of heating the wire 1 at a pre-heating temperature between 50 and 1000 °C.

[0052] The heating intensity of the pre-heating system 140 can be controlled by configuring one or more pre-heating operating parameters (e.g., pre-heating power level, pre-heating temperature, number of active operating heaters, etc.). For example, the heating intensity of the pre-heating system 140 can be varied by controlling the pre-heating power level (i.e., the amount of power supplied to the pre-heating system 140); in this case, increasing the value of the pre-heating power level leads to an increase in the pre-heating temperature of the wire 1, while reducing the pre-heating power level leads to a decrease in the pre-heating temperature of the wire 1. Alternatively, or in addition, the pre-heating system 140 may accept an input value representing the pre-heating temperature of the wire 1; in this case, the pre-heating system 140 can comprise, for example, a feedback loop system configured to automatically control and maintain the wire 1 at said target pre-heating temperature. For example, the pre-heating system 140 can comprise a temperature sensor unit (e.g., a thermocouple or an infrared sensor) placed in proximity of the wire 1 and configured to measure the temperature of the moving wire 1 when exiting the pre-heating system 140. The temperature measured by the temperature sensor unit can be compared to a target pre-heating temperature and employed to make appropriate adjustments in order to achieve and maintain said target pre-heating temperature (e.g., the pre-heating power level can be automatically adjusted based on such comparison).

[0053] According to an aspect of the present invention, the pre-heating system 140 comprised in the apparatus 100 can be configured to control the amount of coating material 2 applied on the wire 1. In particular, the temperature difference between the wire 1 entering the coating chamber 110 and the coating material 2 contained in it has a direct impact on the friction between the coating material 2 and the surface of the wire 1. More specifically, the friction between the coating material

[0054] 2 and the surface of the moving wire 1 facilitates the creation of an initial layer of coating material 2 on the surface of the wire 1 as soon as it enters the coating chamber 110. The final quantity of coating material 2 built upon said initial layer of coating material 2 by means of the hydrodynamic forces generated in the coating chamber 110 is typically proportional to the amount of said initial layer. Therefore, the quantity of coating material 2 finally laid on the wire 1 exiting the coating chamber 110 directly depends on the extent of said initial layer of coating material 2 and, indirectly, on the initial friction encountered by the wire 1 when entering the coating chamber 110. As the friction between the wire 1 and the coating material 2 can be directly managed by controlling the temperature difference between the wire 1 entering the coating chamber 110 and the molten coating material 2 contained in it, it is possible, according to an aspect of the present invention, to control the final quantity of coating material 2 applied on the wire 1 by properly operating the pre-heating system 140.

[0055] In particular, according to an aspect of the present invention, the pre-heating system 140 can be configured to heat the wire 1 at a pre-heating temperature, whereas said pre-heating temperature is based on at least one target geometrical parameter of the coating layer 12 of the wire 1. More specifically, said at least one target geometrical parameter can comprise at least one target thickness parameter of the coating layer 12. Said thickness parameter can be, for example, a numerical value directly representing the thickness of the coating layer 12 in at least one point along the section of the wire 1 ; alternatively or in addition, said thickness parameter can be, for example, a numerical value indirectly representing the average thickness of the coating layer 12 (e.g., the perimeter of the coating layer 12, the average thickness calculated over multiple points around the surface of the wire 1, etc.). As the pre-heating temperature of the wire 1 entering the coating chamber 110 is directly correlated with the amount of coating material 2 deposited on the wire 1, said thickness of the coating layer 12 can be precisely controlled by properly configuring one or more operating parameters of the pre-heating device 140 (e.g., the pre-heating temperature, the pre-heating power level, the number of active operating heaters, etc.)

[0056] For example, according to an aspect of the present invention, the pre-heating device 140 can be operated according to at least one pre-heating operating parameter wherein said pre-heating operating parameter is determined based on at least one target thickness parameter of the coating layer 12. To this end, a transfer function correlating said at least one pre-heating operating parameter with said at least one thickness parameter can be employed to determine the value of said pre-heating operating parameter on the basis of said target thickness parameter of the coating layer 12 of the wire 1. Said transfer function can be determined, for example, experimentally, by correlating a plurality of known pre-heating operating parameters to a plurality of thickness parameters directly measured on the wire 1 exiting the coating chamber 110; for example, while keeping all the operating settings of the apparatus 100 unchanged (e.g., type of coating material 2, temperature and pressure inside the coating chamber 110, speed of the wire 1, etc.), the thickness of the coating layer 12 can be continuously measured while the pre-heating operating parameter is varied according to a predetermined pattern. Measured data can then be used to determine the relationship between the pre-heating operating parameter and the thickness parameter of the coating layer 12. As already mentioned above, said pre-heating operating parameters can comprise the pre-heating power level and / or the pre-heating temperature. Accordingly, a first pre-heating transfer function correlating the pre-heating power level with said at least one value of thickness of the coating layer 12 can be employed to determine the value of said pre-heating power level on the basis of a target value of thickness of the coating layer 12 of the wire 1. Similarly, a second transfer function correlating the pre-heating temperature with said at least one value of thickness of the coating layer 12 can be employed to determine the value of said pre-heating temperature on the basis of a target thickness parameter of the coating layer 12 of the wire 1.

[0057] Alternatively, or in addition, the operating parameters of the pre-heating system 140 can be periodically adjusted on the basis of at least one target thickness parameter and at least one measured thickness parameter. More specifically, a thickness parameter of the coating layer 12 can be measured on the wire 1 as it exits the coating chamber 110 and then compared with at least one target thickness parameter; for example, said comparison may comprise the deviation between the measured thickness parameter of the coating layer 12 and said at least one target thickness parameter. Based on such a comparison, one or more operating parameters of the pre-heating system 140 such as, for example, the value of the pre-heating power level or the pre-heating temperature, can be configured accordingly.

[0058] To this end, according to an aspect of the present invention, the apparatus 100 for coating a wire 1 may comprise a measuring unit 160 configured to perform one or more measurements of one or more geometrical parameters of the coating layer 12 applied on the wire 1. For example, the measuring unit 160 may be configured to measure a thickness parameter of the coating layer 12 applied on the wire 1 in one or more predetermined points along the cross-section of the coated wire 1. The measuring unit 160 may comprise, for example, one or more coaxial laser displacement sensors configured for measuring the thickness of the coating layer 12 applied on the wire 1 in one or more predetermined points along the cross-section of the coated wire 1.

[0059] Figure 2 shows a method 200 for configuring and / or controlling the quantity of coating material 2 applied on the wire 1 by the apparatus 100 for coating a wire 1; more specifically, according to an aspect of the present invention, the method 200 allows to initialize and / or to continuously monitor and adjust said at least one thickness parameter of the coating layer 12 applied on the wire 1.

[0060] At step 201, the pre-heating system 140 can be initialized by configuring one or more pre-heating operating parameters of the pre-heating system 140 based on said at least one target geometrical (in particular, thickness) parameter of the coating layer 12. As explained above, said one or more pre-heating operating parameters can be determined as a function of said at least one target thickness parameter by means, for example, of said first transfer function or by means of said second transfer function. Although optional, said initialization step (i.e., step 201) may help stabilizing the apparatus 100 before starting the phase of continuously monitoring and adjusting the pre-heating operating parameters (i.e., steps 202-204). Conversely, when the apparatus 100 exhibits high level of stability and / or when said first or said second transfer functions are characterized by a high level of accuracy, the method 200 for controlling the quantity of coating material 2 applied on the wire 1 may stop at step 201. For example, when the apparatus 100 operates in a completely isolated environment, the phase of continuously adjusting and monitoring (i.e., steps 202-204) the apparatus 100 may result unnecessary as the operating conditions of the apparatus 100 are likely to remain stable over a long period of time.

[0061] Alternatively or in addition, the method 200 can proceed with step 202 wherein at least one measured geometrical (in particular, thickness) parameter of the coating layer 12 applied on the wire 1 exiting the coating chamber 110 is acquired; for example, said thickness parameter can be measured by means of the measuring unit 160.

[0062] At step 203, the measured geometrical (in particular, thickness) parameter is compared with at least one target geometrical (in particular, thickness) parameter; for example, at step 203, the deviation between the measured thickness parameter and the target thickness parameter can be calculated.

[0063] At step 204, at least one pre-heating operating parameter is adjusted based on the comparison carried out at step 203; for example, said at least one pre-heating operating parameter can be adjusted based on the deviation between the measured thickness parameter and the target thickness parameter. As explained above, if said deviation indicates a lack of coating material 2 on the wire 1 (i.e., the measured thickness is less than the target thickness), the pre-heating parameter (e.g., the pre-heating temperature or the pre-heating power level) can be determined in order to improve the friction between the wire 1 and the coating material 2 contained in the coating chamber 110 thereby augmenting the final quantity of coating material 2 laid on the wire 1. On the contrary, when said deviation indicates an abundance of coating material 2 on the wire 1 (i.e., the measured thickness is more than the target thickness), the pre-heating parameter can be determined in order to reduce the friction between the wire 1 and the coating material 2 contained in the coating chamber 110 thereby reducing the quantity of coating material 2 laid on the wire 1. In general, high pre-heating temperatures lead to low friction levels while low pre-heating temperatures lead to high levels of friction.

[0064] The pre-heating operating parameters can be adjusted, for example, by means of said first and second transfer function; alternatively, the adjustments of the pre-heating operating parameter can be determined through a Proportional Integral Derivative controller (PID). The method 200 can iterate through steps 202-204 in order to continuously monitor and adjust, when necessary, the pre-heating operating parameters.

[0065] According to an aspect of the present invention, the apparatus 100 for coating a wire 1 may further comprise a control unit 170 (shown in Fig. 3), operatively connected to a wire positioning device 150 (hereinafter described), to the measuring unit 160 and to the pre-heating system 140. The control unit 170 may comprise, for example, a memory unit 171 for storing one or more computer programs along with operating real-time data, a processor unit (CPU) 172 capable of executing one or more computer programs, a communication interface 173 configured to receive and send data from and to one or more external devices (for example, a measuring device), an input / output interface 174 configured to receive and send data from and to an external device (for example, a keyboard, a second control unit, etc.). The control unit 170 can also comprise a display 175 and one or more control devices 176 (e.g., an integrated keyboard, a plurality of control switches, etc.). The control unit 170 may comprise, for example, a programmable logic controller (PLC). The control unit 170 may be operatively connected to the measuring unit 160 and to the pre-heating system 140 by means, for example, of a dedicated communication bus in order to send and receive data to and from the measuring unit 160 and the pre-heating system 140. According to an aspect of the present invention, the control unit 170 may be configured to execute the method 200 as shown in Fig. 2. At step 201, the control unit 170 may initialize the pre-heating system 140 by configuring at least one pre-heating operating parameter based on at least one target thickness parameter of the coating layer 12; the target thickness parameter can be acquired by means of, for example, said input / output interface 174. At step 202, the control unit 170 can acquire at least one measured thickness parameter of the coating layer 12 applied on the wire 1 exiting the coating chamber 110; to this end, the measuring unit 160 can be configured to periodically or continuously provide one or more thickness measurements to the control unit 170 by means of said dedicated communication bus. The control unit 170 can be configured to compare, at step 203, said at least one measured thickness parameter with at least one target thickness parameter and to adjust, at step 204, said at least one pre-heating operating parameter of the pre-heating system 140.

[0066] The coating apparatus 100 according to the present invention may comprise a system 150 for positioning and / or guiding the moving wire 1 (also referred to as “wire positioning device 150” or “wire positioning system 150” in rest of the present description) according to a predetermined trajectory across the coating chamber 110 (i.e., the path followed by the wire 1 in its motion through the coating chamber 110); as already described above, the inlet opening 111 and the outlet opening 112 according to the present invention are configured to allow the wire 1 to follow a plurality of trajectories across the coating chamber 110. The trajectory of the wire 1 arranged by the wire positioning device 150 may be comprised in said plurality of trajectories. For example, the wire positioning device 150 can be configured to allow positioning the wire 1 according to any of the trajectories comprised in said plurality of trajectories; in particular, the wire positioning device 150 can be configured to dynamically vary the trajectory of the moving wire 1 during the wire coating process. In order to arrange the wire 1 according to a predetermined trajectory across the coating chamber 110, the wire positioning device 150 can be physically located before and / or after the coating chamber 110. In particular, the wire positioning device 150 can be configured to vary and / or control the position of the moving wire 1 before entering the coating chamber 110 or after exiting the coating chamber 110.

[0067] According to an aspect of the present invention, the wire positioning device 150 is configured to vary and / or control the entry position of the moving wire 1 into the coating chamber 110 through the inlet opening 111.

[0068] As already described above, according to an aspect of the present invention, the profile of the inlet opening 111 of the coating chamber 110 is configured to be larger than the section of the wire 1 so as to allow the wire 1 to enter the coating chamber 110 according to a plurality of entry positions; an entry position of the wire 1 can comprise an entry point 401, and optionally, an entry orientation. An entry point 401 is the point through which the wire 1 enters the coating chamber 110 through the inlet opening 111 ; it can be defined, for example, using a combination of coordinates indicating its location with respect to the inlet opening 111 (e.g., with respect to a two-dimensional Cartesian coordinates system laying on a plane orthogonally intersecting the coating chamber 110 in correspondence with the inlet opening 111). Correspondingly, an entry orientation of the wire 1 is the attitude according to which the wire 1 enters the coating chamber 110 through the inlet opening 111; it can be defined, for example, using a plurality of entry angles (e.g., a roll angle, a pitch angle, and a yaw angle) with respect to a system of coordinates.

[0069] Figure 4a shows a front cross-sectioned view of the inlet opening 111 of the coating chamber 110 where reference number 401 indicates an entry point of the wire 1; the entry point 401 can be defined by a combination of coordinates through a Cartesian coordinate system with the origin located at the center of the inlet opening 111. If the cross-section of the wire 1 is not rounded (e.g., a rectangular section), the entry orientation of the wire 1 may comprise an entry roll rotation 402 defined, for example, by a roll angle.

[0070] Figure 4b shows a side cross-sectioned view of the coating chamber 110 wherein the entry orientation of the wire 1 comprises an entry pitch rotation 403 defined, for example, by a pitch angle. Figure 4c shows a top cross-sectioned view of the coating chamber 110 wherein the entry orientation of the wire 1 comprises an entry yaw rotation 404 defined, for example, by a row angle. Figures 5a, 5b, and 5c depict a preferred embodiment of the wire positioning system 150 configured to vary and control the entry position of the wire 1 entering the coating chamber 110. The system 150 can comprise a wire straightener 151 configured to straighten the wire 1 and to maintain it in a predetermined entry position. The wire straightener 151 can comprise a plurality of rollers configured in a plurality of rows and arranged either in a single plane or in a plurality of straightening planes; for example, as shown in Figures from 5a to 5c, the system 150 can comprise two sets of rollers each configured into two rows and arranged in two orthogonal straightening planes. Preferably, rollers can be adjusted, either manually or through one or more motorized actuators, to allow accurate strengthening settings. The wire straightener 151 can be arranged in a fixed position on a mobile platform 152 configured to move horizontally and vertically and, optionally, to rotate around one or more axes. For example, the mobile platform 152 can comprise a multi-directional positioning system configured to enable movements of the mobile platform 152 in both vertical and horizontal directions; the multi-directional positioning system can be operated manually or by means of proper motorized actuators and can comprise a combination of two or more linear motion devices so as to enable the mobile platform 152 to be precisely positioned and maneuvered in multiple directions. For example, as shown in figure 5a, 5b, and 5c the multidirectional positioning system can comprise a lifting mechanism 153 and a horizontal motion system 154. In particular, the lifting mechanism 153 can comprise hydraulic or pneumatic cylinders, electric motors, gears, pulleys, or scissor mechanisms configured to elevate the mobile platform 152; similarly, the horizontal motion system 154 may comprise sliders or wheels that allow the mobile platform 152 to slide or roll horizontally. As the wire straightener 151 is arranged in a fixed position on the mobile platform 152, the entry point 401 of the wire 1 directly depends on the position of the mobile platform 152; therefore, the multi-directional positioning system comprised in the wire positioning system 150 is configured to vary in a controlled manner (or to control) the entry point 401 of the wire 1.

[0071] Further, the wire positioning system 150 can comprise a roll-axis rotation system 155 configured to attain controlled rotation of the mobile platform 152 along a rotational-longitudinal axis z’ (e.g., also referred to as roll-axis, i.e., an axis of rotation extending along the length of the mobile platform 152 and parallel to the line along which the wire 1 stretches).

[0072] Alternatively or in addition, the wire positioning system 150 can further comprise a pitch-axis rotation system (not depicted in the embodiment shown in Figures 5a, 5b, and 5c) configured to rotate the mobile platform 152 along a rotational-transverse axis x’ (e.g., also referred to as pitch axis, i.e., an axis extending in the direction of the width of the mobile platform 152 and orthogonal to the line along which the wire 1 stretches).

[0073] Alternatively, or in addition, the wire positioning system 150 can further comprise a yaw-axis rotation system (not depicted in the embodiment shown in Figures 5a, 5b, and 5c) configured to rotate the mobile platform 152 along a vertical axis y’ (e.g., also referred to as yaw axis, i.e., an axis perpendicular to the roll axis and the pitch axis).

[0074] The roll-axis rotation system 155 as well as the pitch-axis and the yaw-axis rotation systems may comprise a manual or motorized system of pulleys and belts (or any other suitable means) configured to produce torque and initiate the rotation of the mobile platform 152.

[0075] By controlling the rotation of the mobile platform 152 along at least one axis among the roll-axis, the pitch axis, and the yaw axis, the wire positioning system 150 allows to vary in a controlled manner the entry orientation of the wire 1 wherein the entry orientation of the wire 1 comprises at least one among the roll rotation 402, the pitch rotation 403, and the yaw rotation 404. Depending on the configuration of the apparatus 100 and, in particular, depending on the configuration of its coating chamber 110, it is sometimes unnecessary to fully control the entry orientation of the wire 1. For example, according to the embodiment of the wire positioning system 150 shown in Figure 5a, 5b, and 5c, the wire positioning system 150 may allow to control exclusively the roll rotation 402 of the wire 1. Alternatively, the wire positioning system 150 can be configured to vary and / or control at least two among the roll rotation 402, the pitch rotation 403, or the yaw rotation 404 of the wire 1.

[0076] According to an aspect of the present invention, the trajectory across the coating chamber 110 and / or the entry position of the wire 1 can be varied and / or controlled by properly configuring one or more operating parameters of the positioning system 150 (also referred to as “positioning parameters” in the rest of the present description). With reference to the embodiment depicted in Figure 5a, 5b, and 5 c said one or more positioning parameters can comprise, for example, the vertical and horizontal displacement of the mobile platform 152, the roll rotation 402, the pitch rotation 403, the yaw rotation 404, the settings of the wire straightener 151, etc. Independently from the specific embodiment of the positioning system 150, said one or more positioning parameters may refer to any setting of the wire positioning system 150 enabling the variation and the control of the trajectory and / or the entry position of the wire 1.

[0077] As already described above, according to an aspect of the present invention, the profile of the outlet opening 112 is configured to be larger than the section of the coated wire 1 exiting the coating chamber 110; this configuration allows the wire 1 to leave the coating chamber 110 according to a plurality of exit positions each comprising an exit point and an exit orientation. Therefore, according to an aspect of the present invention, the wire 1 can enter the coating chamber 110, navigate through it, and finally exit through the outlet opening 112 without getting in touch with any mechanical component of the apparatus 100. As a result, the coating layer 12 formed around the surface of the wire 1 is deposited and shaped exclusively by the hydrodynamic forces generated by the coating material 2 within the coating chamber 110.

[0078] Contrary to traditional coating techniques (such as, for example, extrusion and enameling coating), the coating apparatus 100 allows to avoid the use of mechanical arrangements for controlling the geometrical properties of the coating layer 12 deposited around the wire 1, such as, for example, a shaping die for determining the shape of the coating layer 12. Instead, the geometrical properties (e.g., the thickness, the shape, the cross-section outline, etc.) of the coating layer 12 deposited around the surface of the wire 1 by the apparatus 100 are exclusively determined by the intensity and the distribution of the hydrodynamic forces exerted on the surface of the wire 1 along its trajectory across the coating chamber 110; as a consequence, the geometrical features of the coated wire 1 exiting the coating chamber 110 depend directly on the trajectory followed by the wire 1 across the coating chamber 110 and are not correlated to the shape of the outlet opening 112.

[0079] Therefore, as the final geometrical parameters of the coating layer 12 deposited on the wire 1 heavily hinges on the intensity and the distribution of such hydrodynamic forces across the coating chamber 110, it becomes of paramount importance to allow the attainment of precise control over the trajectory followed by the wire 1 across the coating chamber 110. According to an aspect of the present invention, the wire positioning system 150 can be configured to control the trajectory of the wire 1 across the coating chamber 110, wherein said trajectory is determined on the basis of at least one or more target geometrical parameters of the coating layer 12 of the wire 1. As the trajectory of the wire 1 across the coting chamber 110 heavily relies on the entry position of the moving wire 1 into the coating chamber 110, the wire positioning system 150 can be configured to vary and / or control the entry position of the wire 1 into the coating chamber 110, wherein said entry position is determined on the basis of at least one or more target geometrical parameters of the coating layer 12 of the wire 1. Alternatively, or in addition, the wire positioning system 150 can be configured to operate according to one or more positioning parameters, wherein said one or more positioning parameters are determined on the basis of at least one or more target geometrical parameters of the coating layer 12 of the wire 1.

[0080] Due to the complexity of the distribution of the hydrodynamic forces within the coating chamber 110, neither the trajectory of the wire across the coating chamber 110 nor the entry position of the wire 1 have a straightforward and easily predictable relationship with the geometrical parameters of the coating layer 12 of the wire 1 leaving the coating chamber 110. For example, in order to apply a concentric layer of coating material 2 on the surface of the wire 1 (i.e., a layer of coating material 2 characterized by uniform thickness around the surface of the wire 1), traditional centering procedures (e.g., centering the wire with respect to the inlet opening 111 of the coating chamber 110) do not always lead to acceptable results.

[0081] According to an aspect of the present invention, the relationship between the positioning parameters of the wire positioning system 150 and the geometrical properties of the wire 1 exiting the coating chamber 110 can be expressed using, for example, a transfer function (also referred to as “positioning transfer function”). Said positioning transfer function can be determined, for example, experimentally, by correlating a plurality of positioning parameters to a plurality of geometrical parameters of the coating layer 12 directly measured on the wire 1 exiting the coating chamber 110; for example, while keeping all the operating settings of the apparatus 100 unchanged (e.g., type of coating material 2, temperature and pressure inside the coating chamber 110, speed of the wire 1, etc.), the geometrical parameters of the coating layer 12 can be continuously measured while varying the positioning parameters of the wire positioning system 150. Measured data can be then used to determine said positioning transfer function modelling the relationship between the target geometrical parameters of the coating layer 12 and the positioning parameters. Similarly, the positioning transfer function can be determined to model the relationship between the target geometrical parameters of the coating layer 12 and the entry position of the wire 1.

[0082] Alternatively, or in addition, one or more positioning parameters of the wire positioning system 150 can be continuously or periodically adjusted on the basis of one or more target geometrical parameters and one or more measured geometrical parameters. More specifically, one or more geometrical parameters of the coating layer 12 can be measured by the measuring unit 160 as the wire 1 exits the coating chamber 110 and then compared with said one or more target geometrical parameters; for example, said comparison may comprise the deviation between the one or more measured geometrical parameters of the coating layer 12 and said one or more target geometrical parameters. Based on such a comparison, one or more positioning parameters of the positioning system 150 can be configured accordingly.

[0083] Figure 6 shows a method 600 for controlling one or more geometrical parameters of the coating layer 12 applied on the wire 1 by the apparatus 100 for coating a wire 1; more specifically, according to an aspect of the present invention, the method 600 allows to initialize and / or to continuously adjust and monitor said one or more geometrical parameters of the coating layer 12 applied on the wire 1. At step 601 , the wire positioning device 150 can be initialized by configuring at least one operating parameter of the wire positioning system 150 on the basis of said one or more target geometrical parameters of the coating layer 12 of the wire 1. As explained above, said at least one positioning operating parameter can be determined as a function of said one or more target geometrical parameters by means, for example, of said positioning transfer function. Although optional, said initialization step (i.e., step 601) may help stabilizing the apparatus 100 before starting the phase of continuously adjusting and monitoring it (i.e., steps 602-604). Conversely, when the apparatus 100 exhibits a high level of stability and / or when said positioning transfer function is characterized by a high level of accuracy, the method 600 may stop at step 601. For example, when the apparatus 100 operates in a completely isolated environment, the phase of continuously adjusting and monitoring (i.e., step 202-204) the apparatus 100 may result unnecessary as the operating conditions of the apparatus 100 are likely to remain stable over a long period of time.

[0084] Alternatively or in addition, the method 600 can proceed with step 602 (also called “acquisition step 602”) wherein said one or more measured geometrical parameters of the coating layer 12 applied on the wire 1 exiting the coating chamber 110 are acquired; for example, said one or more geometrical parameters can be measured by means of the measuring unit 160.

[0085] At step 603 (also called “comparation step 603”), the one or more measured geometrical parameters are compared with one or more target parameters; for example, at step 603, the deviation between the one or more measured geometrical parameters and said one or more target geometrical parameter can be determined.

[0086] At step 604 (also called “adjusting step 604”), at least one positioning parameter is adjusted based on the comparison carried out at step 603; for example, said at least one positioning parameter can be adjusted based on the deviation between the one or more target geometrical parameters and the one or more measured geometrical parameters. Said at least one positioning parameter can be adjusted, for example, by means of said positioning transfer function; alternatively or in addition, the adjustments of the positioning parameter can be determined through a multivariate Proportional Integral Derivative controller (PID). The method 600 can iterate through steps 602- 604 in order to continuously monitor and adjust, when necessary, the at least one positioning parameter of the wire positioning system 150.

[0087] According to an aspect of the present invention, the control unit 170 can be operatively connected to the wire positioning device 150 and configured to execute the method 600 as shown in Fig. 6. At step 601, the control unit 170 may initialize the wire positioning system 150 by configuring at least one positioning operating parameter based on at least one target geometrical parameter of the coating layer 12; the geometrical parameter can be acquired by means of, for example, said input / output interface. At step 602, the control unit 170 can acquire one or more geometrical parameters of the coating layer 12 applied on the wire 1 exiting the coating chamber 110; to this end, the measuring unit 160 can be configured to periodically or continuously provide one or more measurements of the geometrical parameters to the control unit 170 by means of said dedicated communication bus. The control unit 170 can be configured to compare, at step 603, said one or more measured geometrical parameters with one or more target geometrical parameters and to adjust, at step 604, said at least one positioning parameters of the wire positioning system 150. Figures 7a, 7b, 7c, and 7d show a cross-section of a plurality of coated wires la, lb, 1c, and Id comprising at least one rectangular conductor 11 and at least one layer of coating material 2 characterised by one or more geometrical parameters 701-712. The distribution of the coating layer 12 around the conductor 11 can be expressed by means of said plurality geometrical parameters 701-712 of the coating layer 12. For example, the geometrical parameters 701-712 of the coating layer 12 can comprise one or more thickness parameters defining the value of the thickness of the coating layer 12 in one or more target points around the surface of the conductor 11.

[0088] Figure 7a shows a coated wire la comprising a rectangular conductor 11 and a coating layer 12 uniformly distributed around its surface. In this case, the value of the geometrical parameters 701- 712 of the coated wire la may be equal or similar in all the target points around the cross-section of the wire la.

[0089] Fig. 7b, 7c, and 7d show a coated wire lb, 1c, and Id wherein the coating layer 12 is characterized by a non-uniform distribution around the surface of the conductor 11 (i.e., the conductor 11 and the coating layer 12 are not co-cantered). In this case, the target geometrical parameters 701-712 define a pre-determined non-uniform distribution of the coating layer 12 around the conductor 11. For example, Fig. 7b show a coated wire lb comprising a rectangular conductor 11 wherein, although each side of the rectangular conductor 11 is characterized by a uniform coating layer 12, at least two sides of the coting layer 12 are characterized by different geometrical parameters (i.e., the coating layer 12 on two opposite sides of the rectangular conductor 11 is characterized by different thickness). Fig. 7c show a coated wire 1c comprising a rectangular conductor 11 wherein the coating layer 12 is uniform on each side of the conductor 11 but characterized by different geometrical parameters with respect to the other sides of the conductor. Fig. 7d shows a coated wire Id wherein the coating layer 12 is characterized by a non-uniform distribution on each side of the rectangular conductor 11.

[0090] Similarly, Fig. 8a and 8b show a cross-section of a first coated wire le and a second coated wire If comprising at least one round conductor 11 and at least one layer of coating material 12 characterised by one or more geometrical parameters 801, 802 (also referred to as target geometrical parameters). Figure 8a shows a coated wire le comprising a round conductor 11 and a coating layer 12 uniformly distributed around its surface (i.e., the conductor 11 is co-centred with respect to the coating layer 12); contrarily, Figure 8b shows a coated wire If whereas the coating layer 12 is characterized by a non-uniform distribution around the conductor 11.

[0091] According to an aspect of the present invention, the method 200 and / or the method 600 can be employed to configure the pre-heating system 140 and / or the wire positioning system 150 based on one or more target geometrical parameters (e.g., the geometrical parameters shown in Figs 7a to 8b). For example, the method 600 can be initially employed to configure and / or control the entry position and, consequently, the trajectory of the wire 1 in order to achieve a coating layer 12 compliant with the target geometrical parameters. For example, assuming to have a set of target geometrical requirements as shown in Fig. 7a, the entry position of the wire 1 can be configured by means of the method 600 in order to achieve a coated wire 1 wherein the conductor 11 is at least co-centred with respect to the coating layer 12. Note that, as explained above, due to the nonuniformity of the hydrodynamic forces within the coating chamber 110, the entry point 401 of the entering wire 1 achieving a co-centred coated wire 1 may not correspond to a trajectory of the wire 1 passing through the centre of the coating chamber 110. In general, according to an aspect of the present invention, the method 600 and the wire positioning system 150 can be employed to attain precise control on the relative position of the conductor 11 with respect to the external surface of the coating layer 12 as define by a set of target geometrical parameters.

[0092] In general, the method 600 can be employed to configure at least one positioning parameter of the wire positioning system 150 to create a coated wire 1 characterized by one or more measured geometrical parameters which are at least proportional to said one or more target geometrical parameters. For example, the target geometrical parameters and the geometrical parameters measured on the wire 1 exiting the coating chamber 110 can be mathematically represented by at least two n-dimensional vectors, GTand GM, respectively; the method 600 can be employed to achieve a coated wire 1 wherein the measured vector GMcan be expressed as a linear combination of the target vector GT, i.e., GM= a ■ GT, where a is a scalar factor. Subsequently, the method 200 can be employed in order to adjust the quantity of coating material 2 laid on the wire 1 exiting the coating chamber 110; for example, if the scalar factor a denotes a lack of coating material 2 (i.e., a < 1), the pre-heating operating parameter can be configured to increase the friction between the wire 1 entering the coating chamber 110 and the coating material 2 contained in it (e.g., the pre-heating power can be decreased accordingly); conversely, if the scalar factor a denotes an abundance of coating material 2 (i.e., a > 1), the pre-heating operating parameter can be configured to lower the friction between the wire 1 entering the coating chamber 110 and the coating material 2 contained in it (e.g., the pre-heating power can be increased accordingly). The method 200 and the method 600 can be carried out independently (e.g., simultaneously) or in combination as explained above.

[0093] In the following of the present description there will be described in detail a method 900 for applying a coating material 2 to a wire 1 by means of the apparatus 100 according to the present invention.

[0094] At step 901, the value of one or more operative parameters of the coating apparatus 100 are determined (for example, by said control unit 170) as a function of one or more properties of the coating material 2 to be applied to said wire 1. Said operative parameters can comprise, for example, the power of the heating system 130, the feeding speed of the wire 1, the pressure to be exerted on the coating material 2 by the pressurizer 180, etc.

[0095] For example, the power of the heating system 130 and / or the pressure to be exerted on the coating material 2 by the pressurizer 180 can be determined (for example, by said control unit 170) on the basis of the properties of the coating material 2 to be applied on the wire 106.

[0096] At step 902, the coating apparatus 100 is configured to operate according to the one or more operative parameters determined at step 901. For example, the power of the heating system 140 and / or the pressurizer 180 can be set according to the operative parameters determined at step 901. The method 900 according to the present invention further comprises a step 903 wherein the wire 1 is received at the inlet port 111 of the coating chamber 110 of said coating apparatus 100.

[0097] At step 904, the wire 1 passing through the coating chamber 110 is coated by the liquid coating material 2 contained in the coating chamber 110, carrying away from the chamber 110 an amount of coating material 2 which corresponds to the coating layer 12 applied on the outer surface of the wire 1 ; at step 904, a layer of coating material 2 is therefore applied to the wire 1.

[0098] At step 905, the method 900 further comprises one or more steps of the method 600 for configuring and / or controlling one or more geometrical parameters of the coating layer 12 applied on the wire 1 by means of the coating apparatus 100. Alternatively, or in addition, at step 906, the method 900 may further comprise one or more steps of the method 200 for configuring and / or controlling the quantity of coating material 2 applied on the wire 1 by the apparatus for coating a wire 100.

[0099] Finally, the method 900 further comprises a step 907 wherein the wire 1 is released through an outlet port 112 of the coating chamber 110.

[0100] Thanks to the above described structural and functional characteristics of the present invention, an apparatus 100 and a method 900 for coating a wire 1 with a layer of coating material 2 according to a predetermined set of geometrical requirements is achieved. The apparatus 100 according to the present invention allow to continuously monitor and dynamically adjusting the geometrical parameters of the coating layer 12 of the wire 1 exiting the coating apparatus 100.

[0101] Further, the apparatus 100 according to the present invention allows to apply a layer of coating material 2 characterized by uniform geometrical parameters over the entire length of the wire 1.

[0102] Further, the apparatus 100 according to the present invention is configured to allow the wire 1 to follow a plurality of trajectories across the coating chamber 110 and to dynamically vary the trajectory of the wire 1 during the coating operations.

[0103] Naturally, while the principle of the invention remains the same, the details of construction and the embodiments may widely vary with respect to what has been described and illustrated purely by way of example, without departing from the scope of the present invention.

Claims

CLAIMS1. An apparatus (100) for applying a layer of coating material (2) to a wire (1), said apparatus (100) comprising: a coating chamber (110) for applying a coating material (2) to a wire (1) passing through the coating chamber (110), wherein the coating chamber (110) comprises an inlet opening (111) configured for receiving the wire (1) and an outlet opening (112) configured for releasing the wire (1), said inlet opening (111) and said outlet opening (112) being configured to allow the wire (1) to follow a plurality of trajectories across said coating chamber (110); an elongate injection channel (120) comprising an opening (125) for receiving a predetermined quantity of coating material (2), said elongate injection channel (120) being configured to be in communication with the coating chamber (110); at least one heating system (130) configured to raise the temperature of the coating material (2) as the coating material (2) flows through the injection channel (120); a wire positioning device (150) configured to position the wire (1) according to a trajectory across the coating chamber (110), wherein said trajectory is comprised in said plurality of trajectories.

2. Apparatus (100) according to claim 1, wherein said wire positioning device (150) is configured to allow the positioning of the wire (1) according to any of the trajectories comprised in said plurality of trajectories.

3. Apparatus (100) according to one or more of the preceding claims, wherein said wire positioning device (150) allows to dynamically vary the trajectory of the wire (1) across the coating chamber (HO).

4. Apparatus (100) according to one or more of the preceding claims, wherein said trajectory is determined on the basis of one or more target geometrical parameters of the coating layer (12) of the wire (1).

5. Apparatus (100) according to one or more of the preceding claims, wherein said inlet opening ( 111 ) is configured to allow the wire ( 1 ) to enter the coating chamber (110) according to a plurality of entry positions and wherein said wire positioning device (150) is configured to arrange the wire (1) according to at least one entry position, said at least one entry position being determined based on one or more target geometrical parameters of said layer of coating material (2).

6. Apparatus (100) according to claim 5, wherein said entry position comprises an entry point(401) and / or an entry orientation.

7. Apparatus (100) according to claim 6, wherein said wire positioning device (150) comprises at least one of:- a multi-directional positioning system configured to control the entry point (401) of the wire (i);- a roll-axis rotation system (155) configured to control a roll rotation (402) of the wire (1);- a pitch-axis rotation system configured to control a pitch rotation (403) of the wire (1);- a yaw-axis rotation system configured to control a yaw rotation (404) of the wire (1).

8. Apparatus (100) according to one or more of the preceding claims, wherein the wire positioning device (150) comprises one or more positioning parameters and wherein the trajectory of the wire (1) and / or the entry position of the wire (1) depends on said one or more positioning parameters.

9. Apparatus (100) according to one or more of the preceding claims, further comprising a measuring unit (160) configured to obtain one or more measured geometrical parameters of the coating layer (12) applied on the wire (1).

10. Apparatus (100) according to claim 9, further comprising a control unit (170) operatively connected to the wire positioning device (150) and the measuring unit (160), said control unit (170) being configured to initialize and / or to continuously adjust one or more positioning parameters of the wire positioning device (150) based on one or more target geometrical parameters of said layer of coating material (2) and / or said one or more measured geometrical parameters.

11. Apparatus (100) according to one or more of the preceding claims, further comprising a preheating system (140) configured to heat the wire (1) before entering the coating chamber (110), said pre-heating system (140) being operated according to at least one pre-heating operating parameter, wherein said pre-heating operating parameter is determined based on at least one target geometrical parameter of said layer of coating material (2).

12. A wire positioning device (150) configured to operate with an apparatus (100) for applying a layer of coating material to a wire (1) comprising: a coating chamber (110) for applying a coating material to a wire (1) passing through the coating chamber (110), wherein the coating chamber (110) comprises an inlet opening (111) configured for receiving the wire (1) and an outlet opening (112) configured for releasing the wire (1), said inlet opening (111) and said outlet opening (112) being configured to allow the wire (1) to follow a plurality of trajectories across said coating chamber (110);an elongate injection channel (120) comprising an opening (125) for receiving a predetermined quantity of coating material, said elongate injection channel (120) being configured to be in communication with the coating chamber (110); at least one heating system (130) configured to raise the temperature of the coating material as the coating material flows through the injection channel (120); said wire positioning device (150) being configured to position the wire (1) according to a trajectory across the coating chamber (110), wherein said trajectory is comprised in said plurality of trajectories.

13. A method (900) for applying a coating material (2) to a wire (1) by means of an apparatus (100) according to one or more claims from 1 to 11, the method (900) comprising the following steps:901 determining one or more operative parameters of the coating apparatus (100);902 configuring the apparatus (100) according to said operative parameters;903 receiving the wire (1) at an inlet port (111) of a coating chamber (110) of said coating apparatus (100) for applying the coating material (2) to the wire (1);904 applying a layer of coating material (2) to the wire (1);905 configuring and / or controlling one or more geometrical parameters of the coating layer (12) applied on the wire (1) by means of one or more of the following steps:601 configuring at least one positioning parameter of a wire positioning device (150) based on one or more target geometrical parameters of the coating layer (12) of the wire (1);602 acquiring one or more measured geometrical parameters of the coating layer (12) applied on the wire (1) exiting the coating chamber (110);603 comparing said one of more measured geometrical parameters with said one or more target geometrical parameters;604 adjusting said at least one positioning parameter; wherein the method (900) further comprises a step (907) of releasing the wire (1) through an outlet port (112) of the coating chamber (110) of said coating apparatus (100).

14. Method (900) according to claim 13, further comprising a step (906) of configuring and / or controlling the quantity of coating material (2) applied on the wire (1) by the apparatus (100) for coating a wire (100) by means of one or more of the following steps:201 configuring at least one pre-heating operating parameter of the pre-heating system (140) based on at least one target geometrical parameter of the coating layer (12);202 acquiring at least one measured geometrical parameter of the coating layer (12) applied on the wire (1) exiting the coating chamber (110); 203 comparing said at least one measured geometrical parameter with at least one target geometrical parameter;204 adjusting said at least one pre-heating operating parameter.

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