Apparatus and method for applying a coating material to a wire

Abstract

The present invention relates to an apparatus (100) for applying a coating material to a wire (106), the apparatus (100) comprising: a coating chamber (102) for applying a coating material to a wire (106) passing through the coating chamber (102), the coating chamber (102) having an inlet port (120) configured to receive the wire (106) and an outlet port (121) configured to discharge the wire (106); an elongated injection channel (103) having a first portion (131) and a second portion (132), the first portion (131) including an opening (130) for receiving a predetermined amount of coating material in a solid state, the second portion (132) being in communication with the coating chamber (102); and at least one heating element (104) configured to increase the temperature of the coating material as it flows through the injection channel (103). According to the invention, the coating device (100) further comprises: a pressurizer (105) configured to operate according to a first operating phase, in which the pressurizer (105) applies a predetermined pressure to the coating material in the first portion (131) of the injection channel (103), and a second operating phase, in which the pressurizer (105) is in a position in which the injection channel (103) can receive a predetermined amount of solid coating material; and a cooling system (119) configured to cool at least a portion of the first portion (131) of the injection channel (103).

Description

[Technical Field]

[0001] The present invention relates to the field of apparatus for coating wires with a layer of coating material. More particularly, the present invention relates to a type of coating apparatus capable of applying a layer of coating material onto a wire without using any kind of solvent (also referred to elsewhere in this specification as a solventless coating apparatus). An example of a solventless coating apparatus can be found in document EP 3192081, which is assigned to the same assignee.

[0002] A solventless coating apparatus according to the present invention comprises a coating chamber for applying a coating material to a traveling wire; an elongated injection channel for receiving, heating and supplying the coating material to the coating chamber; and a pressurizer configured to pressurize the coating material within the injection channel.

[0003] As is well documented in the aforementioned publications, one of the key aspects of a solventless coating apparatus relies on the ability to accurately maintain the coating material in the coating chamber at a predetermined constant pressure and temperature. For this reason, it is of utmost importance to accurately control both the amount of coating material delivered to the coating chamber and the pressure applied thereto.

[0004] According to known coating techniques (e.g., based on extrusion coating), the coating material is typically delivered to the coating apparatus by a single device (e.g., a pump or screw feeder) and simultaneously pressurized. While such devices are cost- and space-efficient, they do not allow for precise control of the amount of coating material injected into the system and the pressure simultaneously applied thereto. As a result, the coating layer on wires processed by known coating techniques is typically characterized by poor mechanical and thermal properties. For example, the shape and thickness of the coating layer deposited on the wire by known coating techniques are usually not adjustable or fine-tuneable. Another typical problem with known coating apparatuses is their limited operating range, which prevents the use of particularly difficult coating materials. An example of such a known coating device can be found in U.S. Pat. No. 4,252,755.

[0005] In contrast to known coating devices, the solventless coating apparatus of the present invention includes a dedicated supply system configured to precisely calibrate the amount of solid coating material (e.g., powder, pellets, particles, cartridges, etc.) delivered to the inlet channel of the coating apparatus. The solventless coating apparatus of the present invention further includes a dedicated pressurizer configured to pressurize the solid coating material after it enters the inlet channel. By employing two dedicated devices (i.e., the supply system and the pressurizer), the solventless coating apparatus of the present invention can precisely control both the amount of coating material delivered to the inlet channel (also referred to elsewhere herein as volume) and the pressure simultaneously applied thereto. Furthermore, precise control of both volume and pressure can indirectly control the residence time of the coating material within the coating apparatus (i.e., the time interval occurring from when the coating material is introduced into the inlet channel to when the coating material exits the solventless coating apparatus). This is particularly true when employing difficult coating materials (e.g., thermosetting polymers) that quickly begin to degrade and harden (e.g., reticulate) when exposed to high temperatures.

[0006] As described in more detail elsewhere herein, a pressurizer according to the present invention is configured to cause a coating material to flow through an injection channel toward a coating chamber; and at the same time, the injection channel is configured to gradually heat the coating material as it flows toward the coating chamber so that it reaches a predetermined viscosity and temperature.

[0007] To prevent chemical and physical degradation of the coating material, it is essential to avoid stagnation and overheating of the coating material along the injection channel. In particular, imprecise temperature control of the coating material in the injection channel can lead to premature melting of the coating material and recirculation around the working area of ​​the pressurizer, thereby increasing the probability of its degradation. For example, if prematurely melted coating material comes into direct contact with the pressurizer, it can cause partial or total clogging of the pressurizer, leading to stagnation and subsequent degradation of the coating material left behind on the pressurizer surface. As a result, imprecise temperature control can lead to pressurizer inefficiency and even failure, thus preventing the solventless coating apparatus from achieving optimal performance. In this regard, it is worth noting that the use of a closed pressurizer is highly undesirable because it increases the complexity and cost of the apparatus and, more importantly, requires high maintenance. Furthermore, as will become clear elsewhere in this specification, a closed pressurizer would result in significant pressure changes within the coating chamber during the operation of loading solid coating material into the apparatus.

[0008] Therefore, to solve these and other problems, it is essential to ensure precise temperature control of the coating material within the injection channel, for example, to prevent the coating material from prematurely melting in an uncontrolled manner. Furthermore, for the reasons explained above, it is desirable to prevent any direct contact between the molten coating material and the pressurizer; for example, it is advantageous to ensure that the layer of coating material to which the pressurizer applies pressure remains in a solid state (i.e., powder, pellets, particles, etc.).

[0009] The present invention arose from the desire to overcome the above-mentioned problems that may arise during the operation of the solventless coating apparatus described in the aforementioned patent EP 3192081, and therefore to provide a coating apparatus that is improved in many respects.

[0010] The object of the present invention is to provide a coating device of the type indicated at the beginning of this specification, which is therefore easier to maintain and which is improved in terms of temperature control during operation.

[0011] It is a further object of the present invention to provide a coating apparatus that can avoid stagnation and overheating of the coating material along the injection channel.

[0012] It is a further object of the present invention to provide a coating apparatus that allows for simple cleaning and maintenance operations.

[0013] It is a further object of the present invention to provide a coating apparatus which prevents pressurizer failure and inefficiency.

[0014] It is a further object of the present invention to provide a coating apparatus that allows for precise control of both the volume and pressure within the coating chamber.

[0015] A further object of the present invention is to provide a coating apparatus of the type indicated at the beginning of this specification, which extends the range of operating parameters such as pressure, temperature, wire speed and wire coating thickness, thereby achieving wires with coating layers made of polymeric materials that are extremely difficult to process with known techniques.

[0016] To achieve these objects, the present invention relates to an apparatus for coating a wire having all the features set out in the appended claim 1. The present invention also relates to a method for applying a coating material to a wire.

[0017] Further objects, features and advantages of the present invention will become apparent from the following detailed description and with reference to the accompanying characteristics, given solely as non-limiting examples. [Brief explanation of the drawings]

[0018] [Figure 1a]1 shows a cross-sectional front view of a first preferred embodiment of an apparatus for coating wires according to the present invention during a first operation phase; [Figure 1b] 1 shows a cross-sectional front view of a first preferred embodiment of a device according to the present invention during a second operation phase; [Figure 2] 1 shows an enlarged perspective view of a second embodiment of the device according to the invention; [Figure 3] 1 shows a diagram of a method for applying a coating material to a wire according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] In the following description, various specific details are set forth for the purpose of providing a thorough understanding of one or more example embodiments. An embodiment may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. References to "one embodiment" in the context of this specification indicate that a particular configuration, structure, or feature described in connection with that embodiment is included in at least one embodiment. Thus, phrases such as "in one embodiment" that may appear in various places in this specification do not necessarily refer to the same embodiment. Moreover, particular features, structures, or features may be combined in any suitable manner in one or more embodiments and / or may be associated with embodiments in different ways than shown herein; for example, features illustrated herein in connection with one drawing may apply to one or more embodiments illustrated in a different figure.

[0020] The references exemplified herein are for convenience only and therefore do not limit the field of protection or the scope of the embodiments.

[0021] In the accompanying drawings, reference numeral 100 generally designates a first preferred embodiment of an apparatus for applying a coating material to a wire 106 according to the present invention. The apparatus 100 can be used to apply a coating material to any type of wire 106, avoiding the use of solvents as a primary agent for applying the coating to the wire 106 while ensuring optimal mechanical and thermal properties of the resulting coated wire 106. The wire 106 can comprise any type of metal, such as copper, aluminum, or steel. Copper and aluminum wires 106 are typically used in electrical applications, such as electromagnet windings. The coating material can be any type of coating material; for example, the coating material can include a plastic coating material, such as a thermosetting polymer or a thermoplastic polymer.

[0022] 1a and 1b, a coating apparatus 100 according to the present invention comprises a coating chamber 102 for applying a coating material to a wire 106 passing through the coating chamber 102; for this purpose, the coating chamber 102 has an inlet port 120 configured to receive the wire 106 and an outlet port 121 configured to discharge the wire 106. More specifically, the coating chamber 102 has the inlet port 120 through which the wire 106 can pass and enter the coating chamber 102, and the outlet port 121 through which the wire 106 can emerge from the coating chamber 102 together with an outer layer of coating material.

[0023] The applied coating may include any type of coating material, such as, for example, a thermosetting or thermoplastic polymer material. Thermosetting materials generally allow for higher quality coatings than thermoplastic materials and perform better at higher temperatures. The specific type of thermosetting or thermoplastic material used may vary depending on the type of metal from which the wire 106 is made and / or the properties required for the coating, depending on the end use for which the wire 106 is manufactured. Thermosetting polymers may include any of polyester, epoxy-polyester blends, polyethylene, polyurethane, polyethyleneimine, polyamide, polyimide, polyamideimide, thermosetting polyvinyl formal compounds, epoxies, polyesterimides, polyvinyl fluoride (PVF), and other materials. The coating material may be a mixture of any of these polymers, as well as other substances, particularly thermosetting additives. For example, a mixture containing 60% polyvinyl formal and 40% thermosetting additive, or a mixture of polyesterimide and amideimide, may be used as the coating material.

[0024] The thermoplastic polymer may include, for example, perfluoroalkoxy (PFA), 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), and polyvinyl fluoride (PVF).

[0025] 1a, 1b, and 2, the apparatus 100 further comprises an injection channel 103 for receiving a predetermined amount of solid coating material at the opening 130 and supplying the received coating material to a coating chamber 102 disposed in communication with an end 133 of the elongated injection channel 103. More specifically, the injection channel 103 has a first portion 131 including the opening 130 for receiving the solid coating material, and a second portion 132 configured to communicate with the coating chamber 102.

[0026] The coating chamber 102 is configured to be in fluid communication with the end 133 of the injection channel 103, allowing the passage of coating material from the injection channel 103 to the coating chamber 102 and allowing smooth propagation of pressure from the injection channel 103 to the coating chamber 102.

[0027] Prior to being delivered to the injection channel 103, the coating material is in a solid state, for example, as a powder, solid pellet, chip or cartridge, or other solid form commonly known for paints and enamels.

[0028] 1a and 1b, according to one aspect of the present invention, the coating material can be inserted into the injection channel 103 by an automated feeding system 200 configured to feed the coating material into the injection channel 103 through an opening 130. Preferably, the opening 130 is provided in a side of the injection channel 103.

[0029] According to known techniques, the automatic feeding system 200 comprises a hopper 201 provided for inserting the solid coating material, for example in powder form, and a duct 202 connecting the hopper 201 with the opening 130. A screw feeding element 203 may be provided in said duct 202, which rotates in the duct 202 and feeds the coating material through the duct 202 until it reaches the opening 130 and thus into the injection channel 103.

[0030] 1a, 1b, and 2, the coating apparatus 1 may include a support casing having a plurality of casings 109, 110, 111 rigidly connected to one another. The support casings (i.e., each of the casings 109, 110, 111) may preferably be made of a thermally conductive material, such as metal, to ensure that uniform heating of the coating material is maintained within each thermal zone of the apparatus 100 (particularly by the heating element 104, described below).

[0031] The first portion 131 of the injection channel 103 may be located, for example, in the upper casing 111, and the second portion 132 may be located, for example, in the intermediate casing 110. Furthermore, the injection channel 103 may have a cylinder (in particular a metal cylinder) containing both the first portion 131 and the second portion 132 of the injection channel 103, which may be inserted, for example, inside one or more of the aforementioned casings 110, 111 of the device 100.

[0032] According to one embodiment of the present invention, the aforementioned injection channel 103 has a cylindrical shape with a constant diameter over its entire length, thus avoiding bottleneck-like shapes that may hinder the flow of the coating material. This shape of the injection channel 103 allows for efficient fluid transfer of the coating material towards the coating chamber 102 and easy cleaning and maintenance operations of the injection channel 103.

[0033] Furthermore, the shape of the injection channel 103, which does not provide any narrowing, can provide a wide opening for the coating material to flow into the coating chamber 102, thus maximizing the flow of the coating material within the coating chamber 102 and facilitating cleaning and maintenance operations.

[0034] As described in detail elsewhere herein, to achieve a desired viscosity of the coating material in the coating chamber 102, the coating apparatus 100 according to the present invention is configured to gradually heat the coating material as it flows through the inlet channel 103. More specifically, the coating apparatus 100 is configured to move solid coating material inserted into a first portion 131 of the inlet channel 103 to a second portion 132 of the inlet channel 103, where the solid coating material is gradually melted until it reaches a desired viscosity and density.

[0035] To this end, the coating apparatus 100 according to the present invention further comprises a pressurizer 105 configured to pressurize the coating material in the injection channel 103 and thereby force the coating material to flow through the injection channel 103 .

[0036] The apparatus 100 according to the present invention also includes at least one heating element 104 that is controllable to gradually increase the temperature of the coating material as it flows through the inlet channel 103, thereby achieving a desired viscosity of the coating material in the coating chamber 102. By precisely controlling the temperature across the inlet channel 103 of the coating apparatus 100, the molten coating material is applied directly to the wire 106 passing through the coating chamber 102.

[0037] As described in more detail elsewhere in this specification, once the required pressure is reached, the pressurizer 105 does not pressurize the coating material any further, but it can be configured to maintain a predetermined constant pressure within the injection channel 103 and the coating chamber 102.

[0038] As shown in Figures 1a and 1b, according to one embodiment of the present invention, the pressurizer 105 may have a stem 155 that is driven axially along the length of the injection channel 103 by an actuator 118 (e.g., an electrically operated actuator).

[0039] The pressurizer 105 may further include a cylinder rigidly connected to the stem 155 and driven by an actuator 118 configured to effectively regulate the pressure within the coating chamber 102 by dynamically adjusting the movement of the cylinder and stem 155 as the coating material advances through the injection channel 103.

[0040] Furthermore, stem 155, driven by actuator 118 for example, ensures a fast response time for controlling the pressure according to the required high operating speed of device 100. Details of actuator 118 are not shown in the accompanying drawings because they can be provided according to any known configuration and omitting such details from the drawings makes the drawings easier to understand.

[0041] In order to avoid direct contact between the pressurizer 105 and the liquid coating material contained in the second portion 132 of the injection channel 103, the pressurizer 105 is configured to follow a cyclical operating mode, with each cycle (of said cyclical operating mode) having a first operating phase (also referred to elsewhere in this specification as the "pressurizing phase"; see FIG. 1A) for pressurizing the coating material contained in the first portion 131 of the injection channel 103, and a second operating phase (also referred to elsewhere in this specification as the "loading phase"; see FIG. 1B) for allowing said injection channel 103 to receive a predetermined amount of solid coating material.

[0042] More specifically, the pressurizer 105 according to the present invention is configured to operate according to a first operating phase, in which the pressurizer 105 applies a predetermined pressure to the coating material contained in said first portion 131 of said injection channel 103, and a second operating phase, in which the pressurizer 105 releases the pressure from the coating material to allow said injection channel 103 to receive a predetermined amount of solid coating material. More specifically, during said second operating phase, the pressurizer 105 is in a position that allows said injection channel 103 to receive a predetermined amount of solid coating material.

[0043] During the pressurization phase, a predetermined pressure is exerted by the pressurizer 105 only on the solid coating material contained in said first portion 131 of the injection channel 103 .

[0044] For clarity, it is worth noting that, at least during the pressurization phase, the amount of coating material contained in the inlet channel 103 gradually decreases as the wire 106 passing through the coating chamber 102 gradually carries away some of the coating material. As a result, to maintain a constant pressure on the coating material in the coating chamber 102, the pressurizer 105 needs to adapt its position within the inlet channel 103. More specifically, according to one embodiment of the present invention, the stem 155 of the pressurizer 105 can gradually move downward in the inlet channel 103 as the amount of coating material in the inlet channel 103 decreases. According to a further aspect of the present invention, to avoid any contact between the coating material in a liquid state and the pressurizer 105, the pressurization phase can be terminated before the stem 155 reaches the portion of the inlet channel 103 where the coating material is in a liquid state. For example, the pressurization phase can be terminated before the pressurizer 105 (e.g., the stem 155) reaches the second portion 132 of the inlet channel 103. To this end, the aforementioned pressurizer 105 has a stroke length, the stroke length of the pressurizer 105 being limited to the aforementioned first portion 131 of the injection channel 103; i.e., the aforementioned stroke length can be configured to limit the movement of the pressurizer 105 into the first portion 131 of the injection channel 103, particularly during the pressurization phase. In this way, the possibility of the pressurizer 105 coming into direct contact with the coating material in a liquid state contained in the second portion 132 of the injection channel 103 can be minimized.

[0045] As shown in FIG. 1a, according to a further aspect of the present invention, during the pressurization phase, the pressurizer 105 (e.g., stem 155) can preferably be configured to engage with the opening 130 of the injection channel 103 to avoid any pressure leakage. As a result, the pressure exerted on the solid coating material contained in the first portion 131 of the injection channel 103 can be fully transmitted to the second portion 132 of the injection channel 103 and, consequently, to the coating material contained in the coating chamber 102. According to a specific embodiment of the present invention, the stem 155 can be configured to engage with and cover the opening 130 before contacting the solid coating material contained in the first portion 131 of the injection channel 103. For example, as shown in FIG. 1a, during the pressurization phase, the stem 155 can be configured to fully lock the opening 130 of the injection channel 103 to prevent the coating material from leaking back into the duct 202 during the pressurization phase. As a result, the pressure exerted on the solid coating material in the first portion 131 of the injection channel 103 can be completely transmitted to the coating material contained in the second portion 132 of the injection channel 103 and, consequently, to the coating material in the coating chamber 102. It is noteworthy that, thanks to the aforementioned features, the complexity and maintenance of the coating apparatus 100 are improved.

[0046] Furthermore, as shown in FIG. 1b, at the start of the loading phase, the pressurizer 105 can be configured to release pressure from the solid coating material and move to a position where the aforementioned injection channel 103 can receive a predetermined amount of solid coating material. According to one embodiment of the present invention, after the end of the pressurization phase (or at the start of the loading phase), the stem 155 can release the pressure of the coating material by moving upward along the injection channel 103. In particular, as shown in FIG. 1b, the stem 155 can be configured to fully disengage from the opening 130 (e.g., unlock the opening 130) to connect the duct 202 with the injection channel 103 so as to allow the injection channel 103 to receive the solid coating material.

[0047] Furthermore, the amount of solid coating material loaded into the injection channel 103 during the loading phase can be determined to achieve multiple advantageous effects. For example, the amount of solid coating material loaded into the injection channel 103 can be determined as a function of the speed at which the coating material exits the coating apparatus 100 (i.e., the amount of coating material carried away from the coating chamber 102 by the traveling wire 106 per unit time). Furthermore, according to a preferred embodiment of the present invention, the amount of solid coating material loaded into the injection channel 103 during each loading phase can be determined so that the pressurizer 105 can fully engage the opening 130 of the injection channel 103 during the pressurization phase. More specifically, at the start of each pressurization phase, the stem 155 moves downward along the injection channel 103 until it reaches the surface of the solid coating material inserted into the injection channel 103 during the loading phase. To properly lock the opening 130 during the pressurization phase, the upper surface of the solid coating material loaded into the injection channel 103 needs to be between the opening 130 and the end 133 of the injection channel 103. As a result, as the pressurizer 105 moves downward, it always engages the opening 130 before reaching the surface of the solid coating material.

[0048] The amount of coating material exiting the apparatus 100 can be calculated or estimated according to known techniques. For example, the amount of coating material exiting the apparatus 100 in each operating cycle can be determined experimentally prior to production.

[0049] Alternatively or additionally, the injection channel 103 may have a measuring means for measuring the amount of coating material remaining in the injection channel 103 at the end of each pressurization phase. For example, the injection channel 103 may have at least one sensor located in the first portion 131 of the injection channel 103 for measuring the amount of solid coating material contained in said first portion 131 of the injection channel 103. The said at least one sensor may be operatively connected to the supply system 200, thereby enabling the supply system 200 to accurately control the amount of coating material inserted into the injection channel 103 based on the readings of the said at least one sensor. Generally, the amount of coating material inserted into the injection channel 103 in each loading phase may be determined based on the amount of coating material contained in the injection channel 103 at the start of the loading phase.

[0050] Furthermore, while ensuring that the opening 130 is completely locked during the pressurization phase, the amount of coating material inserted into the injection channel 103 can be determined to maximize the duration of the pressurization phase; as a result, the time ratio between the pressurization phase and the duration of the overall working cycle (i.e., also referred to as the duty cycle of the apparatus 100) can be maximized, with the result that pressure fluctuations in the coating chamber 102 are minimized.

[0051] As previously indicated, the coating apparatus 100 according to the present invention comprises a support casing, for example comprising a plurality of casings 109, 110, 111 rigidly connected to one another. The support casing may preferably be made of a thermally conductive material, such as metal, to ensure that uniform heating of the coating material by the heating elements 104 is maintained within each thermal zone of the apparatus 100.

[0052] In the preferred embodiment shown in the drawings, the support casing of the coating apparatus 100 comprises a lower casing 109 containing the coating chamber 102 and the end 133 of the injection channel 103 .

[0053] However, with reference to the preferred embodiment, the support casing comprises an intermediate casing 110 containing a plurality of the aforementioned heating elements 104 and the aforementioned second portion 132 of the injection channel 103 .

[0054] However, with reference to the preferred embodiment, the support casing further comprises an upper casing 111 which includes a first portion 131 of the injection channel 103 and an opening 130 for receiving the coating material.

[0055] As previously indicated, the at least one heating element 104 can be configured to heat various portions of the apparatus to gradually increase the temperature of the coating material as it flows through the injection channel 103 to achieve a desired viscosity of the coating material in the coating chamber 102. Precise temperature control and material flow throughout the apparatus 100 allows for the use of difficult coating materials, such as thermosetting materials, and prevents degradation and hardening of the material within the apparatus 100.

[0056] According to one embodiment of the present invention, the at least one heating element 104 includes a first series of heating elements 104 located in the lower casing 109 and a second series of heating elements 104 located in the intermediate casing 110.

[0057] To this end, the lower casing 109 may have a number of holes to allow the heating elements 104 to pass through. Preferably, the first series of heating elements 104 comprises two rows of three heating elements 104, one row located along each side of said coating chamber 102.

[0058] The intermediate casing 110 may have a second series of heating elements 104 positioned perpendicular to the aforementioned inlet channel 103. The second series of heating elements 104 may be formed by pairs of heating elements 104, each pair spaced apart from one another at a regular pitch along the outer surface of the intermediate casing 110 to provide uniform heating of the second portion 132 of the inlet channel 103.

[0059] Thanks to the above-described arrangement of the heating elements 104, the apparatus 100 is able to achieve excellent uniformity of heat exchange between the heating elements 104 and the coating material contained in the injection channel 103 and the coating chamber 102.

[0060] According to the embodiment shown in the drawings, which provides a support casing having three casings 109, 110, 111, the coating apparatus 100 has three main temperature zones, one for each of the three casings 109, 110, 111. This is a particularly preferred number of temperature zones and casings for efficient operation. However, it is possible to provide embodiments including two temperature zones and casings, or more than three casings and temperature zones, without departing from the scope of the present invention.

[0061] In this regard, in the second portion 132 of the injection channel 103 (e.g., corresponding to the intermediate casing 110), the coating material is heated to a temperature higher than that of the first portion 131 (i.e., the zone of the upper casing 111); therefore, the viscosity of the coating material contained in the second portion 132 of the injection channel 103 is reduced relative to the viscosity of the solid-state coating material present in the first portion 131 of the injection channel 103 provided in the upper casing 111. The coating material may be in a liquid state in the second portion 132 of the injection channel 103 and in the zone of the lower casing 109. Preferably, when a thermosetting polymer is employed, the maximum temperature of the coating chamber 102 is controlled to be high enough to completely liquefy the coating material, but lower than the temperature at which the thermosetting material hardens.

[0062] According to one aspect of the invention, the coating apparatus 100 comprises a cooling system 119 for cooling at least a portion of the aforementioned first portion 131 of the inlet channel 103. According to one embodiment of the invention, the cooling system 119 is configured to provide a flow of liquid coolant into at least one duct located in the aforementioned support casing of the apparatus 100, thereby cooling at least a portion of the inlet channel 103 (i.e., the first portion 131 of the inlet channel 103) and, together with the heating element 104, providing the coating material with a precise and sharp temperature field as it flows towards the coating chamber 102.

[0063] Preferably, the cooling system 119 has at least one duct, in particular having a spiral shape, said at least one duct being located within said upper casing 111 (i.e., the first portion 131 of the injection channel 103) and extending around said first portion 131 of the injection channel 103.

[0064] The circulation of coolant within the cooling system 119 is particularly useful when performing operating coating cycles with very high operating temperatures (i.e., operating cycles that include at least a loading phase and a pressurization phase), because under these operating conditions it is extremely difficult to maintain the operating temperature at the required value due to heat conduction from the lower casing 109 to the intermediate and upper casings 110, 111, whose operating temperatures are lower than those provided by the lower casing 109.

[0065] Thus, the combination of heating provided by heating element 104 and cooling provided by cooling system 119 can provide much more precise and sharper temperature regimes and control of the viscosity of the coating material as it flows through various portions of injection channel 103.

[0066] Furthermore, the precise temperature control of the coating material achieved by both the heating element 104 and the cooling system 119, combined with the above control of the pressurizer 105, prevents stagnation and overheating of the coating material within the injection channel 103. As previously mentioned, preventing stagnation is of utmost importance when employing thermosetting materials.

[0067] According to one aspect of the present invention, to achieve such technical effect (i.e., preventing stagnation and overheating of the coating material), the cooling system 119 should operate synergistically with the pressurizer 105. In particular, the cooling system 119 should be configured to keep the coating material in a solid state when in contact with the pressurizer 105; at the same time, the cooling system 119 should be configured to avoid any interference with the heating element 104. Therefore, the cooling system 119 is configured to cool only the portion of the injection channel 103 where the pressurizer 105 comes into contact with the solid coating material (i.e., the first portion 131).

[0068] According to one aspect of the present invention, the cooling system 119 can be configured to provide a variable cooling capacity (i.e., the amount of heat removed by the cooling system 119), the variable cooling capacity being determined based on the heat generated by the heating element 104; for example, according to known techniques, a predetermined cooling capacity can be achieved by appropriately controlling the flow of liquid coolant circulating through the cooling system 119. According to the present invention, the cooling capacity provided by the cooling system 119 can be determined and controlled, for example, by a control unit included in the apparatus 100 (or a control unit associated with the apparatus 100), based on the heat generated by the heating element 104; alternatively, the cooling capacity of the cooling system 119 can be predetermined and controlled (e.g., by the control unit) based on, for example, the temperature of the coating material contained in the second portion 132 of the injection channel 103. For this purpose, the injection channel 103 may have one or more temperature sensors operably connected to the cooling system 119 and the aforementioned control unit; the cooling capacity of the cooling system 119 can be determined and controlled (e.g., by the aforementioned control unit) based on one or more readings provided by the aforementioned one or more temperature sensors.

[0069] This is particularly advantageous when multiple coating materials having different physical and chemical properties (e.g., melting temperature, density, viscosity, etc.) are employed in different coating sessions of the same coating apparatus 100. According to one aspect of the present invention, the cooling capacity of the cooling system 119 can be determined (e.g., by the control unit described above) based on the coating material employed in each particular coating session to minimize energy consumption of the cooling system 119.

[0070] With regard to temperature management during operation, preferably the support casing is shaped such that in the configuration in which the device 100 is mounted there are gaps between at least two of the casings 109, 110, 111, thereby allowing air to flow between the casings 109, 110, 111 and preventing the device 100 from overheating due to heat conduction through contact between the casings 109, 110, 111.

[0071] Thanks to these gaps, heat transfer through the casings 109 , 110 , 111 of the coating apparatus 100 is significantly reduced, allowing for easy management of different temperatures in the first portion 131 and the second portion 132 of the injection channel 103 .

[0072] According to another advantageous feature of the invention, the device 100 may comprise an outer casing (not shown in the accompanying drawings) made of insulating material for covering at least the aforementioned lower casing 119 .

[0073] For example, an outer casing of insulating material may cover both the lower casing 109 and the intermediate casing 110, allowing the coating chamber 102 to reach very high temperatures (e.g., greater than 450°C) to adequately melt a wide range of polymers.

[0074] Hereinafter, a method 300 for applying a coating material to a wire 106 by means of an apparatus 100 according to the present invention will be described in detail.

[0075] In step 301, values ​​of one or more operating parameters of the coating apparatus 100 are determined (e.g., by said control unit) as a function of one or more characteristics of the wire 106 (e.g., with respect to the material of the wire 106 and / or with respect to the shape of the wire 106) and / or as a function of one or more characteristics of the coating material applied to said wire 106. Such operating parameters may include, for example, the power of the at least one heating element 104 and the required cooling capacity of the cooling system 119, the feed rate of the wire 106, the pressure exerted on the coating material by the pressurizer 105, etc.

[0076] For example, the power of the heating element 104 and / or the required cooling capacity of the cooling system 119 and / or the pressure exerted on the coating material by the pressurizer 105 can be determined (e.g., by the aforementioned control unit) based on the properties of the coating material applied to the wire 106.

[0077] In step 302, the coating apparatus 100 is configured to operate according to one or more operating parameters determined in step 301. For example, the power of the heating element 104 and / or the cooling capacity of the cooling system 119 can be set according to the operating parameters determined in step 301.

[0078] The method 300 according to the present invention further comprises a stage 303 in which the pressurizer 105 is operated according to the aforementioned loading phase (i.e., the pressurizer 105 is set to a position in which the aforementioned injection channel 103 can receive the aforementioned predetermined amount of solid coating material); in particular, according to one embodiment of the present invention, the stem 155 of the pressurizer 105 is driven to an elevated position, allowing the introduction of the coating material into the injection channel 103, for example by means of the screw feeding element 203 of the automatic feeding system 200.

[0079] Method 300 further comprises step 304, in which pressurizer 105 is operated according to the aforementioned pressurization phase (i.e., applying a predetermined pressure to the coating material in injection channel 103). For example, according to one embodiment of the present invention, actuator 118 of pressurizer 105 moves stem 155 from a raised position to apply a desired pressure to the coating material in injection channel 103 of coating apparatus 100.

[0080] The coating material is pressurized by stem 155 to the pressure required to apply the coating material to wire 106. Once this pressure is reached, stem 155 does not pressurize the coating material any further, but is controlled to maintain the pressure in injection channel 103 and coating chamber 102 approximately constant at the desired value to apply the coating material to wire 106.

[0081] A gradual increase in the temperature of the coating material occurs as the coating material advances through the inlet channel 103. Specifically, in the second portion 132 of the inlet channel 103, the coating material is gradually heated until it reaches a predetermined temperature, thus changing into a liquid state and filling the coating chamber 102.

[0082] The method 300 according to the present invention further comprises a step 305 in which the wire 106 is received at the inlet port 120 of the coating chamber 102 of the coating apparatus 100 and the coating material is applied to the wire 106. Thus, the wire 106 passing through the coating chamber 102 is coated with the liquid coating material located within the coating chamber 102.

[0083] In step 306, the wire 106 is coated with a liquid coating material, and an amount of coating material corresponding to the coating layer applied to the outer surface of the wire 106 is carried away from the chamber 102; thus, in step 306, a layer of coating material is applied to the wire 106.

[0084] The method 300 further comprises a step 307 in which the wire 106 is discharged from the exit port 121 of the coating chamber 102 .

[0085] After step 307, the pressurizer 105 is configured to release pressure from the coating material; then the method 300 according to the present invention cycles back to step 303 (if the properties of the wire 106 and / or coating material are the same as in the previous cycle), otherwise the method 300 cycles back to step 301 (if the properties of the wire 106 and / or coating material are different from those in the previous cycle).

[0086] The wire 106 obtained by the method 300 according to the present invention is characterized by unique thermal and mechanical properties that cannot be achieved by known coating techniques; for example, the method 300 can obtain a wire 106 characterized by optimal adhesion between the wire and the coating layer. The apparatus 100 can also apply a much thicker layer of coating material in one step (i.e., by passing the wire 106 through the apparatus 100 once) than can be achieved by known coating techniques, while ensuring optimal adhesion; in this case, the thickness of the coating layer is actually significantly limited by the presence of solvent in the coating material, which evaporates after the coating procedure. Therefore, with known coating techniques, it is often necessary to apply multiple layers of coating material onto the wire to achieve a given coating layer thickness, thereby compromising the uniformity of the resulting coating layer. In contrast, the apparatus 100 according to the present invention can apply a much thicker layer of coating material onto the wire 106 than can be achieved by known techniques, thereby minimizing the number of layers of coating material. Therefore, the wire 106 according to the present invention is characterized by optimal properties, for example, with respect to adhesion, uniformity, smoothness, etc.

[0087] The above structural and functional characteristics of the coating apparatus 100 result in an easily maintainable coating apparatus 100 for applying coating materials to the wire 106, allow for effective temperature control during operation, and expand the range of operating parameters such as pressure, temperature, wire 106 speed, and wire 106 coating thickness, thereby achieving polymer-coated wires 106 that are extremely difficult to process using known techniques.

[0088] Additionally, the coating apparatus 100 according to the present invention provides precise and sharp temperature regimes and control of the viscosity of the coating material as it flows through various portions of the injection channel.

[0089] Furthermore, the coating apparatus 100 according to the present invention can avoid stagnation and thereby avoid degradation of the coating material.

[0090] It will be understood that the principles of the invention will remain the same and that the details of the construction and embodiments may be varied widely from those which have been described and shown solely by way of example, without departing from the scope of the invention.

Claims

1. 1. An apparatus for applying a coating material to a wire, said apparatus comprising: a coating chamber for applying a coating material to the wire passing through the coating chamber, the coating chamber having an inlet port configured to receive the wire and an outlet port configured to discharge the wire; an elongated injection channel having a first portion and a second portion, said first portion comprising an opening for receiving a quantity of coating material in solid state, said second portion communicating with said coating chamber; at least one heating element configured to increase the temperature of said coating material as it flows through said injection channel; and the device further comprises: a pressurizer configured to operate according to a first operating phase in which the pressurizer applies a predetermined pressure to the coating material in the first portion of the injection channel, and a second operating phase in which the pressurizer is in a position in which the injection channel can receive the predetermined amount of solid coating material; a cooling system configured to cool at least part of said first portion of said injection channel; An apparatus comprising:

2. The apparatus further comprising: an upper casing containing said first portion of said injection channel and at least one duct having, in particular, a helical shape, said at least one duct extending around the periphery of said first portion of said injection channel; an intermediate casing containing a plurality of said heating elements and said second portion of said injection channel; a support casing having The apparatus of claim 1 , wherein the cooling system is configured to provide a flow of liquid coolant within the at least one duct.

3. 3. The apparatus of claim 1 or 2, wherein the cooling system is configured to provide a variable cooling capacity, the variable cooling capacity being determined based on the heat generated by the heating element.

4. 4. The apparatus of claim 3, wherein the injection channel has one or more temperature sensors operatively connected to the cooling system, and the variable cooling capacity is determined and controlled based on one or more readings provided by the one or more temperature sensors.

5. 3. The apparatus of claim 1, wherein the pressurizer has a stroke length, the stroke length being restricted to the first portion of the injection channel.

6. 3. The device of claim 1 or 2, wherein the pressurizer is configured to engage the opening of the infusion channel during the first phase of operation.

7. 3. The apparatus of claim 1, wherein the pressurizer has a stem that is driven axially along the length of the first portion of the injection channel by an actuator, thereby effectively regulating the pressure in the coating chamber by dynamically adjusting the movement of the stem as the coating material advances through the injection channel.

8. The apparatus further comprises a supply system for feeding the coating material in the injection channel through the opening, the supply system comprising: a hopper provided for inserting said coating material; a duct connecting said hopper with said opening, a screw feed element located in said duct, rotating therein and forcing said coating material through said duct until it reaches said opening and enters said injection channel; 3. The device according to claim 1 or 2, comprising:

9. 3. A method for applying a coating material to a wire by means of an apparatus according to claim 1 or 2, said method comprising the steps of: determining one or more operating parameters of the device as a function of one or more properties of the wire and / or as a function of one or more properties of the coating material, in particular the one or more operating parameters comprising at least the cooling capacity of the cooling system; - configuring said device to operate in accordance with said one or more operating parameters; - setting the pressurizer in a position where the injection channel can receive the predetermined amount of solid coating material; - operating the pressurizer to obtain a pressurization phase for applying a predetermined pressure to the coating material in the injection channel; - receiving said wire at an inlet port of a coating chamber of said apparatus; - applying a layer of coating material to said wire; - discharging said wire through an outlet port of said coating chamber of said device; A method comprising:

10. Coated wire obtainable by the device according to claim 1 or 2 and the method according to claim 9.

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