Apparatus and method for applying a coating material to a wire

Abstract

The 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), where the coating chamber (102) comprises an inlet port (120) configured to receive the wire (106) and an outlet port (121) configured to release the wire (106); -an elongated injection channel (103) comprising a first portion (131) comprising an opening (130) for receiving a predetermined amount of solid coating material and a second portion (132) in communication with the coating chamber; -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, during which the pressurizer (105) exerts a predetermined pressure on the coating material in the first portion (131) of the injection channel (103), and a second operating phase, during which the pressurizer (105) exerts a predetermined pressure on the coating material in the first portion (131) of the injection channel (103), the pressurizer (105) exerts a predetermined pressure on the coating material in the second portion (131) of the injection channel (103); the pressurizer (105) is in a position allowing the injection channel (3) to receive the predetermined amount of solid coating material; -a cooling system (119) configured to cool at least a portion of said first portion (131) of the injection channel (103).

Description

[0001] The present invention relates to the field of equipment for coating wire with a layer of coating material. More specifically, the present invention relates to the type of coating equipment (also referred to as solventless coating equipment in the remainder of this specification) capable of applying a layer of coating material onto a wire without using any type of solvent. Examples of solventless coating equipment can be found in the document EP3192081 on behalf of the same assignee.

[0002] The solventless coating equipment according to the present invention comprises: a coating chamber for coating a traveling wire with the coating material; an elongated injection channel for receiving, heating the coating material and supplying it to the coating chamber; and a pressurizer configured to press the coating material within the injection channel.

[0003] As fully described in the aforementioned document, one of the key aspects of solventless coating equipment relies on the ability to precisely hold the coating material in the coating chamber at a predetermined constant pressure and temperature. To this end, it is of utmost importance to precisely control the amount of coating material supplied to the coating chamber and the pressure applied to the coating material.

[0004] According to known coating techniques (e.g., based on extrusion coating), the coating material is typically delivered to the coating equipment and simultaneously pressurized by means of a single device (e.g., a pump or a screw feeder); although effective in terms of cost and space, such a device does not allow precise control of the amount of coating material injected into the system and simultaneously precise control of the pressure applied to the coating material; thus, the coating layers of wires processed by known coating techniques typically feature poor mechanical and thermal properties. For example, the geometry and thickness of the coating layer laid on a wire by known coating techniques are generally not adjustable and not fine-tunable. Another typical problem of known coating equipment is its limited operating range, which prevents the use of particularly challenging coating materials. Examples of such known coating equipment can be found in US Patent 4,252,755.

[0005] Contrary to known coating devices, the solventless coating device according to the present invention includes a dedicated feeding system configured to precisely calibrate the amount of solid coating material (such as powder, pellets, granules, cartridges, etc.) delivered to the injection channels of the coating device. The solventless coating device according to the present invention further includes a dedicated pressurizer configured to pressurize the solid coating material after it enters the injection channels. By employing two dedicated devices (i.e., a feeder and a pressurizer), the solventless coating device according to the present invention allows for precise control of the amount of coating material (also referred to as the volume in the remainder of this specification) delivered to the injection channels and simultaneously precise control of the pressure applied to the coating material. Additionally, the precise control of both the volume and the pressure allows for the indirect control of the residence time of the coating material within the coating device (i.e., the time interval occurring from the moment the coating material is introduced into the injection channels until the coating material exits the solventless coating device). This is particularly valuable when using a challenging coating material (such as a thermosetting polymer) that begins to degrade and solidify (e.g., form a network) upon exposure to high temperatures.

[0006] As better explained in the remainder of this specification, the pressurizer according to the present invention is configured such that the coating material flows through the injection channels towards the coating chamber; simultaneously, the injection channels are configured to gradually heat the coating material as it flows towards the coating chamber to reach a predetermined viscosity and temperature.

[0007] To prevent the chemical and physical deterioration of the coating material, it is necessary to avoid the stagnation and overheating of the coating material along the injection channels. In particular, inaccurate temperature management of the coating material within the injection channels may lead to premature melting and recirculation of the coating material around the working area of the pressurizer, thereby increasing its chance of degradation. For example, prematurely melted coating material coming into direct contact with the pressurizer may trigger partial or complete blockage of the pressurizer and cause stagnation and subsequent deterioration of the coating material remaining on the surface of the pressurizer. Therefore, inaccurate temperature management may result in inefficiency or even failure of the pressurizer, thus preventing the solventless coating device from achieving optimal performance. In this regard, it is worth noting that using a sealed pressurizer would be highly undesirable as it would increase the complexity and cost of the device and, more importantly, it would require high maintenance. Additionally, as will become apparent in the remainder of this specification, during the operation for loading the solid coating material into the device, a sealed pressurizer would cause significant changes in the pressure within the coating chamber.

[0008] Therefore, in order to solve these and other problems, it is necessary to ensure precise temperature management of the coating material in the injection channel to prevent, for example, uncontrolled and premature melting of the coating material. Additionally, for the reasons stated above, it is desirable to prevent any direct contact between the molten coating material and the pressure applicator; for example, it is advantageous to ensure that the layer of coating material on which the pressure applicator exerts pressure remains in a solid state (i.e., powder, pellets, granules, etc.).

[0009] The present invention stems from the desire to overcome the above-mentioned problems that may arise during the operation of the solvent-free coating device described in the above-mentioned patent EP3192081, and thus provides a coating device that is improved in many aspects.

[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 easy to maintain and improved from the perspective of temperature management during operation.

[0011] Another object of the present invention is to provide a coating device that allows avoiding stagnation and overheating of the coating material along the injection channel.

[0012] Another object of the present invention is to provide a coating device that allows simple cleaning and maintenance operations.

[0013] Another object of the present invention is to provide a coating device that prevents pressure applicator failures and inefficiencies.

[0014] Another object of the present invention is to provide a coating device that can precisely control the volume and pressure in the coating chamber.

[0015] Another object of the present invention is to provide a coating device of the type indicated at the beginning of this specification, which increases the range of operating parameters (such parameters as pressure, temperature, wire speed, and wire coating thickness) in order to obtain a wire with a coating layer made of a polymer material that is difficult to process with known techniques.

[0016] In view of achieving these objects, the present invention relates to a device for coating a wire, which has all the features indicated in claim 1 appended hereto. The present invention also relates to a method of applying a coating material to a wire.

[0017] Other objects, features, and advantages of the present invention will become apparent from the following detailed description with reference to the appended features, which are given purely by way of non-limiting examples, wherein:

[0018] Figure 1a A cross-sectional front view during a first operating stage of a first preferred embodiment of a device for coating a wire according to the present invention is shown;

[0019] Figure 1bShows a cross-sectional front view of a first preferred embodiment of the device according to the present invention during a second operating phase;

[0020] Figure 2 Shows an enlarged perspective view of a second embodiment of the device according to the present invention;

[0021] Figure 3 Shows a schematic view of a method according to the present invention for applying a coating material to a wire;

[0022] In the following description, various specific details are shown in order to fully understand examples of one or more embodiments. An embodiment can be implemented without one or more specific details, or without 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. References to "embodiments" in the context of this specification indicate that a particular configuration, structure, or feature described with respect to the embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment" (which may occur at different places in this specification) do not necessarily refer to the same embodiment. Moreover, a particular configuration, structure, or feature can be combined in a suitable manner in one or more embodiments and / or associated with the embodiments in a manner different from that shown here. For example, features illustrated with respect to the figures here can be applied to one or more embodiments illustrated in different figures.

[0023] The reference numerals shown here are for convenience only and thus do not limit the scope of the protection or the embodiments.

[0024] In the drawings, reference numeral 100 generally denotes a first preferred embodiment of a device according to the present invention for applying a coating material to a wire 106. The device 100 can be used to apply a coating material to any type of wire 106, avoiding the use of solvents as the main reagent for applying the coating to the wire 106 while ensuring the best mechanical and thermal properties of the resulting coated wire 106. The wire 106 can include any type of metal, such as copper, aluminum, or steel. Copper and aluminum wires 106 are commonly used in electrical applications, such as the windings of electromagnets. The coating material can be any type of coating material; for example, the coating material can include plastic coating materials, such as thermosetting or thermoplastic polymers.

[0025] Reference Figure 1a and Figure 1b, the coating device 100 according to the present invention includes a coating chamber 102 for coating a wire 106 passing through the coating chamber 102; to this end, the coating chamber 102 includes an inlet port 120 configured to receive the wire 106 and an outlet port 121 configured to release the wire 106. More specifically, the coating chamber 102 has an inlet port 120 and an outlet port 121 through which the wire 106 can enter the coating chamber 102, and the wire 106 can exit the coating chamber 102 together with the outer layer of the coating material through the outlet port 121.

[0026] The applied coating can include any type of coating material, such as a thermosetting or thermoplastic polymer material. Generally, thermosetting materials can achieve higher quality coatings and perform better at high temperatures than thermoplastic materials. The specific type of thermosetting or thermoplastic material used can depend on the type of metal used to manufacture the wire 106 and / or the properties of the coating required for the final application (for which the wire 106 is manufactured). Thermosetting polymers can include any one of polyester, epoxy-polyester mixture, polyethylene, polyurethane, polyethyleneimine, polyamide, polyimide, polyamide-imide, thermosetting polyvinyl formal compound, epoxy resin, polyesterimide, polyvinyl fluoride (PVF), and other materials. The coating material can be any one of these polymers and a mixture with other substances (especially thermosetting additives). For example, a mixture containing 60% polyvinyl formal and 40% thermosetting additive or a mixture of polyesterimide and amideimide can be used as the coating material.

[0027] For example, thermoplastic polymers can include perfluoroalkoxy (PFA), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyphenylene sulfide (PPS), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), polyaryletherketone (PAEK), polyamide-imide (PAI), polyvinyl fluoride (PVF).

[0028] Reference Figure 1a , Figure 1b and Figure 2 , the device 100 further includes an elongated injection channel 103 for receiving a predetermined amount of solid coating material at an opening 130 and for supplying the received coating material to the coating chamber 102, and the coating chamber 102 is arranged to communicate with an end 133 of the injection channel 103. More specifically, the injection channel 103 includes a first part 131 and a second part 132, the first part 131 includes an opening 130 for receiving the solid coating material, and the second part 132 is configured to communicate with the coating chamber 102.

[0029] The coating chamber 102 is configured to be in fluid communication with the end 133 of the injection channel 103 for enabling the coating material to pass from the injection channel 103 to the coating chamber 102 and for allowing the smooth propagation of pressure from the injection channel 103 to the coating chamber 102.

[0030] Before being supplied into the injection channel 103, the coating material is in a solid state, such as powder, solid particles, fragments or cartridges, or other solid forms commonly known for paints and enamels.

[0031] As Figure 1a and Figure 1b shown, according to one aspect of the present invention, the coating material can be inserted into the injection channel 103 by means of an automatic feeding system 200, which is configured to drive the coating material through the opening 130 and into the injection channel 103. Preferably, the opening 130 is provided on the side of the injection channel 103.

[0032] According to known techniques, the automatic feeding system 200 includes: a hopper 201, which is provided for inserting a solid coating material in the form of, for example, powder; and a pipe 202 connecting the hopper 201 to the opening 130. A screw feeding element 203 can be provided within the pipe 202 for rotating within the pipe 202 and driving the coating material through the pipe 202 until it reaches the opening 130 and thus enters the injection channel 103.

[0033] As Figure 1a 、 Figure 1b and Figure 2 shown, the coating device 1 can include a support housing, which includes a plurality of housings 109, 110, 111 rigidly connected to each other. The support housing (i.e., each of the housings 109, 110, 111) can preferably be made of a heat-conductive material such as metal to ensure uniform heating of the coating material in each heat zone of the device 100 (especially due to the heating element 104 described below).

[0034] The first part 131 of the injection channel 103 can be located, for example, within the upper housing 111, and the second part 132 can be located, for example, within the intermediate housing 110. In addition, the injection channel 103 can include a cylinder (especially a metal cylinder), which includes both the first part 131 and the second part 132 of the injection channel 103, and the first part 131 and the second part 13 can be inserted into one or more of the housings 110, 111 of the device 100, for example.

[0035] According to an embodiment of the present invention, the injection channel 103 may have a cylindrical shape with a constant diameter along its entire length, thereby avoiding bottleneck-shaped portions that may impede the flow of the coating material. This shape of the injection channel 103 enables efficient fluid transfer of the coating material towards the coating chamber 102, as well as simple cleaning and maintenance operations of the injection channel 103.

[0036] Furthermore, since the geometry of the injection channel 103 does not provide any narrowing, a wide opening can be provided for the coating material towards the coating chamber 102, thus maximizing the flow of the coating material within the coating chamber 102 while facilitating cleaning and maintenance operations.

[0037] As will be described in detail in the remainder of this specification, in order to achieve the desired viscosity of the coating material in the coating chamber 102, the coating device 100 according to the present invention is configured to gradually heat the coating material as it flows through the injection channel 103. More specifically, the coating device 100 is configured to move the solid coating material inserted into the first portion 131 of the injection channel 103 to the second portion 132 of the injection channel 103, where the solid coating material gradually melts until the desired viscosity and density are reached.

[0038] To this end, the coating device 100 according to the present invention further includes a pressure applicator 105, which is configured to press the coating material within the injection channel 103 so as to cause the coating material to flow through the injection channel 103.

[0039] The device 100 according to the present invention further includes at least one heating element 104, which can be controlled to gradually increase the temperature of the coating material as it flows through the injection channel 103, in order to achieve the desired viscosity of the coating material within the coating chamber 102. By precisely controlling the temperature of the entire injection channel 103 of the coating device 100, the molten coating material is directly applied to the wire 106 passing through the coating chamber 102.

[0040] As will be described in more detail in the remainder of this specification, once the required pressure is reached, the pressure applicator 105 no longer pressurizes the coating material, but it can be configured to maintain a constant predetermined pressure within the injection channel 103 and the coating chamber 102.

[0041] As Figure 1a and Figure 1b shown, according to an embodiment of the present invention, the pressure applicator 105 may include a rod 155, which is axially driven along the length of the injection channel 103 by an actuator 118 (e.g., an electrically operated actuator).

[0042] The pressurizer 105 may further include a cylinder rigidly connected to the rod 155 and driven by the actuator 118, and the actuator 118 is configured to effectively adjust the pressure within the coating chamber 102 by dynamically adjusting the movement of the cylinder and the rod 155 as the coating material travels through the injection channel 103.

[0043] In addition, the rod 155 driven by, for example, the actuator 118 ensures a fast response time for controlling the pressure according to the high operating speed required by the device 100. Details of the actuator 118 are not shown in the drawings because they may be provided according to any known configuration and because removing these details from the drawings would make the drawings easier to understand.

[0044] 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 cyclic operating mode, and each cycle of (the cyclic operating mode) includes a first operating phase for pressing the coating material contained in the first portion 131 of the injection channel 103 (also referred to as the "pressing phase" in the remainder of this specification; see Figure 1a ) and a second operating phase for allowing the injection channel 103 to receive a predetermined amount of solid coating material (also referred to as the "loading phase" in the remainder of this specification; see Figure 1b ).

[0045] More specifically, the pressurizer 105 according to the present invention is configured to operate according to the first operating phase and the second operating phase. During the first operating phase, the pressurizer 105 applies a predetermined pressure to the coating material contained in the first portion 131 of the injection channel 103. During the second operating phase, the pressurizer 105 releases the pressure from the coating material to allow the injection channel 103 to receive a predetermined amount of solid coating material. More specifically, during the second operating phase, the pressurizer 105 is in a position that allows the injection channel 103 to receive a predetermined amount of solid coating material.

[0046] During the pressing phase, the pressurizer 105 applies only a predetermined pressure to the solid coating material contained in the first portion 131 of the injection channel 103.

[0047] For the sake of clarity, it is worth noting that, at least during the pressing phase, the amount of coating material contained in the injection channel 103 gradually decreases as the wire 106 passing through the coating chamber 102 gradually carries away a part of the coating material. Therefore, in order to maintain a constant pressure on the coating material in the coating chamber 102, the pressurizer 105 must adjust its position within the injection channel 103. More specifically, according to an embodiment of the present invention, as the amount of coating material in the injection channel 103 decreases, the rod 155 of the pressurizer 105 can gradually move downward along the injection channel 103. According to another aspect of the present invention, in order to avoid any contact between the liquid coating material and the pressurizer 105, the pressing phase can be terminated before the rod 155 reaches the following part of the injection channel 103, in which the coating material is in a liquid state. For example, the pressing phase can be terminated before the pressurizer 105 (e.g., the rod 155) reaches the second part 132 of the injection channel 103. To this end, the pressurizer 105 includes a stroke length, and the stroke length of the pressurizer 105 is limited to the first part 131 of the injection channel 103; that is, the stroke length can be configured to limit the pressurizer 105 from traveling to the first part 131 of the injection channel 103, especially during the pressing phase. In this way, the possibility of the pressurizer 105 coming into direct contact with the liquid coating material contained in the second part 132 of the injection channel 103 can be minimized.

[0048] As Figure 1a shown, according to another aspect of the present invention, during the pressing phase, the pressurizer 105 (e.g., the rod 155) can preferably be configured to engage with the opening 130 of the injection channel 103 to avoid any pressure leakage. Therefore, the pressure applied to the solid coating material contained in the first part 131 of the injection channel 103 can be completely transmitted to the second part 132 of the injection channel 103, and thus to the coating material contained in the coating chamber 102. According to a specific embodiment of the present invention, the rod 155 can be configured to engage and cover the opening 130 before contacting the solid coating material contained in the first part 131 of the injection channel 103. For example, as Figure 1a shown, during the pressing phase, the rod 155 can be configured to completely lock the opening 130 of the injection channel 103 to prevent the coating material from leaking back into the pipeline 202 during the pressing phase. Therefore, the pressure applied to the solid coating material in the first part 131 of the injection channel 103 can be completely transmitted to the coating material contained in the second part 132 of the injection channel 103, and thus completely transmitted to the coating material within the coating chamber 102. It is worth noting that due to the above features, the complexity and maintenance of the coating device 100 are improved.

[0049] In addition, as Figure 1bAs shown, at the beginning of the loading phase, the pressurizer 105 can be configured to release pressure from the solid coating material and move to a position that allows the injection channel 103 to receive a predetermined amount of the solid coating material. According to an embodiment of the present invention, after the termination of the pressing phase (or at the beginning of the loading phase), the rod 155 can release pressure from the coating material by moving upward along the injection channel 103. In particular, as Figure 1b shown, to allow the injection channel 103 to receive the solid coating material, the rod 155 can be configured to be completely disengaged from the opening 130 (e.g., unlock the opening 130) so as to connect the pipe 202 to the injection channel 103.

[0050] In addition, the amount of the solid coating material to be loaded into the injection channel 103 during the loading phase can be determined to achieve various advantageous effects. For example, the amount of the solid coating material to be loaded into the injection channel 103 can be determined according to the rate at which the coating material leaves the coating device 100 (i.e., the amount of the coating material carried away by the traveling wire 106 from the coating chamber 102 per unit time). In addition, according to a preferred embodiment of the present invention, the amount of the solid coating material to be loaded into the injection channel 103 during each loading phase can be determined to allow the pressurizer 105 to be completely engaged with the opening 130 of the injection channel 103 during the pressing phase. More specifically, at the beginning of each pressing phase, the rod 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 allow proper locking of the opening 130 during the pressing phase, the upper surface of the solid coating material loaded in the injection channel 103 must be between the opening 130 and the end 133 of the injection channel 103. Therefore, when moving downward, the pressurizer 105 must engage the opening 130 before reaching the surface of the solid coating material.

[0051] The amount of the coating material leaving the device 100 can be calculated or estimated according to known techniques. For example, the amount of the coating material leaving the device 100 in each working cycle can be determined experimentally before the start of production.

[0052] Alternatively or additionally, the injection channel 103 may include measuring means for measuring the amount of coating material remaining in the injection channel 103 at the end of each pressing phase. For example, the injection channel 103 may include at least one sensor located in a first portion 131 of the injection channel 103 for measuring the amount of solid coating material contained in the first portion 131 of the injection channel 103. The at least one sensor is operatively connected to the feed system 200 to enable the feed system 200 to precisely control the amount of coating material to be inserted into the injection channel 103 based on the readings of the at least one sensor. Generally, the amount of coating material to be 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.

[0053] Furthermore, while ensuring full locking of the opening 130 during the pressing phase, the amount of coating material inserted into the injection channel 103 can be determined so as to maximize the duration of the pressing phase; as a result, the time ratio between the pressing phase and the duration of the entire working cycle (i.e., also referred to as the duty cycle of the device 100) can be maximized, thereby minimizing pressure variations within the coating chamber 102.

[0054] As previously mentioned, the coating device 100 according to the present invention has a support housing that includes, for example, a plurality of housings 109, 110, 111 that are rigidly connected to each other. Preferably, the support housing may be made of a heat-conductive material such as metal to ensure uniform heating of the coating material in each heat zone of the device 100 due to the heating element 104.

[0055] In the preferred embodiment shown in the drawings, the support housing of the coating device 100 includes a lower housing 109 that includes the coating chamber 102 and an end 133 of the injection channel 103.

[0056] Still referring to the preferred embodiment, the support housing includes an intermediate housing 110 that includes a plurality of the heating elements 104 and a second portion 132 of the injection channel 103.

[0057] Still referring to the preferred embodiment, the support housing further includes an upper housing 111 that includes a first portion 131 of the injection channel 103 and an opening 130 for receiving the coating material.

[0058] As previously mentioned, the at least one heating element 104 must be configured to heat different parts of the device so as to gradually raise the temperature of the coating material as it flows through the injection channel 103, in order to achieve the desired viscosity of the coating material within the coating chamber 102. Due to the precise temperature control and material flow throughout the device 100, challenging coating materials, such as thermosetting materials, can be used, thereby preventing material degradation and solidification within the device 100.

[0059] According to an embodiment of the present invention, the at least one heating element 104 includes a first series of heating elements 104 located within the lower housing 109 and a second series of heating elements 104 located within the intermediate housing 110.

[0060] To this end, the lower housing 109 may include a plurality of holes for enabling the heating elements 104 to pass through. Preferably, the first series of heating elements 104 includes two rows of three heating elements 104, each row being positioned along a respective side of the coating chamber 102.

[0061] The intermediate housing 110 may include a second series of heating elements 104 positioned perpendicular to the injection channel 103. The second series of heating elements 104 may be formed by pairs of heating elements 104, each pair of heating elements 104 being spaced apart from each other at a constant spacing along the outer surface of the intermediate housing 110 so as to provide uniform heating of a second portion 132 of the injection channel 103.

[0062] Due to the above-described arrangement of the heating elements 104, the device 100 allows for better uniformity of heat exchange between the heating elements 104 and the coating material contained within the injection channel 103 and within the coating chamber 102.

[0063] According to the embodiment shown in the drawings (which provides a support housing having three housings 109, 110, 111), the coating device 100 has three main temperature zones according to each of the three housings 109, 110, 111. This is a particularly preferred number of temperature zones and housings for efficient operation. However, embodiments including two temperature zones and housings or more than three housings and temperature zones may be provided without departing from the purpose of the present invention.

[0064] In this regard, at the second part 132 of the injection channel 103 (e.g., corresponding to the intermediate housing 110), the coating material is heated to a temperature higher than the temperature of the first part 131 (i.e., the region of the upper housing 111); thus, the viscosity of the coating material contained in the second part 132 of the injection channel 103 is reduced relative to the viscosity of the solid coating material present in the first part 131 of the injection channel 103 provided at the upper housing 111. The coating material can be in a liquid state in the second part 132 of the injection channel 103 and in the region of the lower housing 109. Preferably, when using a thermosetting polymer, the maximum temperature at the coating chamber 102 is high enough to completely liquefy the coating material, but is controlled to be lower than the temperature at which curing of the thermosetting material occurs.

[0065] According to one aspect of the present invention, the coating apparatus 100 includes a cooling system 119 to cool at least a portion of the first part 131 of the injection channel 103. According to an embodiment of the present invention, the cooling system 119 is configured to convey a liquid coolant flow within at least one pipe located within the support housing of the apparatus 100 so as to cool at least a portion of the injection channel 103 (i.e., the first part 131 of the injection channel 103), and to convey a precise and steep temperature profile to the coating material together with the heating element 104 as the coating material flows towards the coating chamber 102.

[0066] Preferably, the cooling system 119 includes at least one pipe, which particularly has a spiral shape, and the at least one pipe is located within the upper housing 111 (i.e., the first part 131 of the injection channel 103) and extends around the first part 131 of the injection channel 103.

[0067] The circulation of the coolant within the cooling system 119 is particularly useful when performing an effective coating cycle with a very high operating temperature (i.e., a work cycle including at least a loading phase and a pressing phase), because under these operating conditions, it is extremely difficult to maintain the operating temperature at the desired value due to the heat conduction from the lower housing 109 to the intermediate housing 110 and the upper housing 111, and in the upper housing 111, the operating temperature is lower than the temperature provided at the lower housing 109.

[0068] Therefore, the combination of heating provided by the heating element 104 and cooling provided by the cooling system 119 enables a more precise and steep temperature profile and control of the viscosity of the coating material as the coating material flows through different parts of the injection channel 103.

[0069] In addition, the precise temperature control of the coating material achieved by means of both the heating element 104 and the cooling system 119, in combination with the control of the above-described pressurizer 105, prevents the stagnation and overheating of the coating material within the injection channel 103. As described above, when using a thermosetting material, preventing stagnation is of utmost importance.

[0070] According to one aspect of the present invention, in order to achieve such a technical effect (i.e., preventing the stagnation and overheating of the coating material), the cooling system 119 must operate in cooperation with the pressurizer 105. In particular, the cooling system 119 must be configured to keep the coating material in a solid state when the coating material comes into contact with the pressurizer 105; at the same time, the cooling system 119 must be configured to avoid any interference with the heating element 104. Therefore, the cooling system 119 is configured to cool only the following part of the injection channel 103 (i.e., the first part 131), in which the pressurizer 105 comes into contact with the solid coating material.

[0071] According to one aspect of the present invention, the cooling system 119 can be configured to provide a variable cooling capacity (i.e., the heat removed by the cooling system 119), wherein the variable cooling capacity is 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 correctly controlling the flow of the liquid coolant circulating in the cooling system 119. According to the present invention, the cooling capacity achieved by the cooling system 119 can be determined and controlled, for example, by a control unit included in the device 100 (or by a control unit associated with the device 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 part 132 of the injection channel 103. To this end, the injection channel 103 can include one or more temperature sensors, which are operatively connected to the cooling system 119 and the control unit; the cooling capacity of the cooling system 119 can be determined and controlled (e.g., by the control unit) based on one or more readings provided by the one or more temperature sensors.

[0072] This is particularly advantageous when multiple coating materials with different physical and chemical properties (e.g., melting temperature, density, viscosity, etc.) are employed during different coating stages of the same coating device 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) based on the coating material employed in each specific coating stage, so as to minimize the energy consumption of the cooling system 119.

[0073] With reference to temperature management during operation, preferably, the support housing is shaped such that in the installed configuration of the device 100, a plurality of gaps are provided between at least two of the housings 109, 110, 111 to allow air to flow between the housings 109, 110, 111 and to prevent the device 100 from overheating due to heat conduction caused by contact between the housings 109, 110, 111.

[0074] Due to these gaps, heat transfer through the housings 109, 110, 111 of the coating device 100 is significantly reduced, enabling easy management of the different temperatures in the first part 131 and the second part 132 of the injection channel 103.

[0075] According to another advantageous feature of the present invention, the device 100 may include an outer housing (not shown in the drawings) made of a heat-insulating material for at least covering the lower housing 119.

[0076] For example, an outer housing made of a heat-insulating material may cover both the lower housing 109 and the intermediate housing 110, such that the coating chamber 102 can reach a very high temperature (e.g., higher than 450 °C) to allow proper melting of a wide range of polymers.

[0077] In the following of this specification, a method 300 for applying a coating material to a wire 106 by means of the device 100 according to the present invention will be described in detail.

[0078] In step 301, (e.g., by the control unit) the values of one or more operating parameters of the coating device 100 are determined based on one or more properties of the wire 106 (e.g., according to the material of the wire 106 and / or according to the geometry of the wire 106) and / or based on one or more properties of the coating material to be applied to the wire 106. The operating parameters may include, for example, the power of 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 applied to the coating material by the pressure applicator 105, etc.

[0079] For example, the power of the heating element 104 and / or the required cooling capacity of the cooling system 119 and / or the pressure applied to the coating material by the pressure applicator 105 may be determined (e.g., by the control unit) based on the properties of the coating material to be applied to the wire 106.

[0080] In step 302, the coating device 100 is configured to operate according to the 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 may be set according to the operating parameters determined in step 301.

[0081] Method 300 according to the present invention further includes step 303, wherein the pressure applicator 105 is operated according to the loading phase (i.e., the pressure applicator 105 is set at a position allowing the injection channel 103 to receive the predetermined amount of solid coating material); in particular, according to an embodiment of the present invention, the rod 155 of the pressure applicator 105 is driven to an elevated position so that the coating material can be input into the injection channel 103 by means of, for example, the screw feed element 203 of the automatic feeding system 200.

[0082] Method 300 further includes step 304, wherein the pressure applicator 105 is operated according to the pressing phase (i.e., a predetermined pressure is applied to the coating material in the injection channel 103). For example, according to an embodiment of the present invention, the actuator 118 of the pressure applicator 105 moves the rod 155 from the elevated position and applies a desired pressure to the coating material within the injection channel 103 of the coating device 100.

[0083] The coating material is pressurized by the rod 155 to the pressure required to apply the coating material to the wire 106. Once this pressure is reached, the rod 155 no longer further pressurizes the coating material, but is controlled to keep the pressure within the injection channel 103 and the coating chamber 102 almost stable at the desired value for applying the coating material to the wire 106.

[0084] As the coating material travels through the injection channel 103, the temperature of the coating material gradually increases. Specifically, at the second part 132 of the injection channel 103, the coating material is gradually heated until it reaches a predetermined temperature, thereby becoming liquid and filling the coating chamber 102.

[0085] Method 300 according to the present invention further includes step 305, wherein the wire 106 is received at the inlet port 120 of the coating chamber 102 of the coating device 100 for applying the coating material 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.

[0086] In step 306, the wire 106 is coated with the liquid coating material, thereby removing a portion of the coating material from the coating chamber 102, and the portion of the coating material corresponds to the coating applied to the outer surface of the wire 106; thus, in step 306, a coating material layer is applied to the wire 106.

[0087] Method 300 further includes step 307, wherein the wire 106 is released through the outlet port 121 of the coating chamber 102.

[0088] After step 307, the press 105 is configured to release pressure from the coating material; then, the method 300 according to the present invention loops back to step 303 (if the properties of the wire 106 and / or the coating material are the same as in the previous cycle), otherwise the method 300 loops back to step 301 (if the properties of the wire 106 and / or the coating material are different from those in the previous cycle).

[0089] The wire 106 obtainable 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 is capable of obtaining a wire 106 characterized by an optimal adhesion between the wire and the coating. While ensuring optimal adhesion, the apparatus 100 is also capable of applying a much thicker layer of coating material in one step (i.e., a single pass of the wire 106 through the apparatus 100) than is achievable by known coating techniques; in this case, the thickness of the coating is actually strongly limited by the presence of solvent in the coating material, which evaporates after the coating process. For this reason, according to known coating techniques, in order to achieve a predetermined thickness of the coating, it is often necessary to apply multiple layers of coating material to the wire, thereby compromising the uniformity of the resulting coating. In contrast, the apparatus 100 according to the present invention is capable of applying a much thicker layer of coating material to the wire 106 than is achievable by known techniques, thereby minimizing the number of coating material layers. Thus, the wire 106 according to the present invention is characterized by optimal properties in terms of, for example, adhesion, uniformity, smoothness, etc.

[0090] Due to the above-described structural and functional features of the coating apparatus 100, an easily maintainable coating apparatus 100 for coating a coating material onto the wire 106 is realized, which enables effective temperature management during operation, thereby increasing the range of operating parameters such as pressure, temperature, wire 106 speed, and wire 106 coating thickness, so as to coat a wire 106 with a polymer that is extremely difficult to process with known techniques.

[0091] In addition, as the coating process flows through different parts of the injection channel, the coating apparatus 100 according to the present invention provides an accurate and steep temperature profile and control over the viscosity of the coating material.

[0092] In addition, the coating apparatus 100 according to the present invention is capable of avoiding degradation of the coating material by avoiding stagnation.

[0093] Of course, while the principles of the present invention remain the same, details of the structure and embodiments can vary greatly from those described and shown by way of example only without departing from the scope of the present invention.

Claims

1. An apparatus (100) for applying a coating material to a wire (106), the apparatus (100) comprising: - A coating chamber (102) for applying the coating material to the wire (106) passing through the coating chamber (102), wherein the coating chamber (102) includes an inlet port (120) configured to receive the wire (106) and an outlet port (121) configured to release the wire (106); - An elongate injection channel (103) including a first portion (131) and a second portion (132), the first portion (131) including an opening (130) for receiving a predetermined amount of solid coating material, and the second portion (132) communicating with the coating chamber (102); - At least one heating element (104) configured to raise the temperature of the coating material as the coating material flows through the injection channel (103), wherein the coating apparatus (100) further comprises: - A pressurizer (105) configured to operate according to a first operating phase and a second operating phase, during the first operating phase, the pressurizer (105) applies a predetermined pressure to the coating material in the first portion (131) of the injection channel (103), and during the second operating phase, the pressurizer (105) is in a position allowing the injection channel (103) to receive the predetermined amount of solid coating material; - A cooling system (119) configured to cool at least a portion of the first portion (131) of the injection channel (103).

2. The device (100) according to claim 1, wherein, The coating apparatus (100) further comprises a support housing, the support housing including: - An upper housing (111) including the first portion (131) of the injection channel (103) and at least one duct, the at least one duct having in particular a spiral shape and extending around the first portion (131) of the injection channel (103); - An intermediate housing (110) including the plurality of heating elements (104) and the second portion (132) of the injection channel (103), wherein the cooling system (119) is configured to convey a liquid coolant flow within the at least one duct.

3. The device (100) according to one or more of the preceding claims, wherein, The cooling system (119) is configured to provide a variable cooling capacity, wherein the variable cooling capacity is determined based on the heat generated by the heating element (104).

4. The device (100) according to claim 3, wherein, The injection channel (103) includes one or more temperature sensors operatively connected to the cooling system (119), wherein the variable cooling capacity is determined and controlled based on one or more readings provided by the one or more temperature sensors.

5. The device (100) according to one or more of the preceding claims, characterized in that, The pressurizer (105) includes a stroke length that is limited to the first portion (131) of the injection channel (103).

6. The device (100) according to one or more of the preceding claims, characterized in that, The pressurizer (105) is configured to engage the opening (130) of the injection channel (103) during the first operating phase.

7. The device (100) according to one or more of the preceding claims, characterized in that, The pressurizer (105) includes a rod (155) that is axially driven along the length of the first portion (131) of the injection channel (103) by an actuator (118) so as to effectively regulate the pressure within the coating chamber (102) by dynamically regulating the movement of the rod (155) as the coating material travels through the injection channel (103).

8. The device (100) according to one or more of the preceding claims, characterized in that, The device (100) further includes a feeding system (200) for driving the coating material within the injection channel (103) through the opening (130), wherein the feeding system (200) includes: - a hopper (201) that is arranged for inserting the coating material; - a pipe (202) that connects the hopper (201) to the opening (130); - a screw feeding element (203) that is provided within the pipe (202) for rotating within the pipe (202) and driving the coating material through the pipe (202) until it reaches the opening (130) and enters the injection channel (103).

9. A method (300) of applying a coating material to a wire (106) by means of a device (100) according to any one of claims 1 to 8, the method comprising the steps of: - determining (301) one or more operating parameters of the coating device (100) based on one or more properties of the wire (106) and / or based on one or more properties of the coating material, in particular, the one or more operating parameters at least include the cooling capacity of the cooling system (119); - configuring (302) the coating device (100) to operate according to the one or more operating parameters; - setting (303) the pressurizer (105) in a position that allows the injection channel (103) to receive a predetermined amount of solid coating material; - operating (304) the pressurizer (105) to obtain a pressing phase for applying a predetermined pressure to the coating material within the injection channel (103); - receiving (305) the wire (106) at the inlet port (120) of the coating chamber (102) of the coating device (100); - applying (306) a layer of coating material to the wire (106); - releasing (307) the wire (106) through the outlet port (121) of the coating chamber (102) of the coating device (100).

10. A coated wire (106) that can be obtained by means of the device (100) according to one or more of claims 1 to 8 and by means of the method (300) according to claim 9.

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