A curing method for wire and bar insulating paint coatings

Abstract

The application discloses a curing method suitable for wire bar insulating paint coating, the thickness and frequency of the insulating paint coating on the surface of the wire bar of the generator stator are controlled, and the insulating paint coating is dried in an infrared light-temperature gradient cooperative curing mode, so that the rapid curing and drying of the insulating paint film are realized; the infrared light wavelength band matched with the paint absorption wavelength is selected, and the temperature range matched with the paint curing is cooperatively controlled, so that the paint film is rapidly cured and the curing effect of the paint film surface is uniform; the application solves the problems of the uneven curing degree of the coating, the long curing time, the strict curing condition requirement and the restriction by the heterogeneous member in the existing method, avoids the problems of the poor paint film curing quality caused by overheating or overcooling, and ensures that the insulating paint coating is free of bubbles, bulges and peeling.

Description

Technical Field

[0001] This invention belongs to the field of stator bar coating technology, specifically relating to a curing method suitable for insulating varnish coatings on stator bars. Background Technology

[0002] Currently, my country's manufacturing capabilities for large high-voltage generators are among the world's leading levels. Stator bars, as one of the core components of a generator, bear the crucial responsibility of energy conversion. Currently, the stator bar voltage level of large high-voltage generators connected to the grid in my country has reached 27kV, and the insulation performance of the stator bars directly affects the reliability and service life of the generator.

[0003] The stator bar insulation primarily employs an epoxy mica insulation system. During long-term operation, it is subjected to the combined effects of electrical, thermal, mechanical vibration, and environmental stress factors, leading to a gradual deterioration of its mechanical and dielectric properties, a reduction in electrical strength, and ultimately, insulation breakdown. Therefore, applying insulating varnish to the stator bar surface for secondary insulation treatment is an effective solution, with anti-corrosion varnish and red enamel being the most commonly used.

[0004] Typically, the curing of insulating varnishes occurs at room temperature through a chemical reaction between the resin and the curing agent. The curing process is affected by factors such as the type of curing agent, external ventilation, humidity, and temperature. This process can easily lead to problems such as prolonged curing time, difficulty in effectively controlling the degree of curing, limited curing performance, and low production efficiency. Besides room temperature curing, convection heating is another common heating method. It involves circulating a heating medium (usually air) between the object's surface and the heating source to transfer heat to the surface. However, this process is prone to problems such as low heating efficiency, slow heating speed, and uneven heating.

[0005] Infrared radiation curing relies on infrared radiation to heat the workpiece and cure the coating. Heat transfer is primarily through infrared radiation, with electromagnetic waves contributing to the energy transfer. However, infrared curing technology prioritizes rapid curing. Since the insulating coating and stator bars have different absorption rates for infrared radiation (the stator bars have relatively low absorption in the infrared band), and the insulating coating absorbs light energy and converts it into heat during infrared heating, excessively rapid curing may result in surface curing while the interior remains incompletely cured, affecting coating quality and insulation performance. Therefore, finding an appropriate curing speed is crucial to ensure overall coating curing. Simultaneously, controlling the surface temperature of the stator bar substrate during infrared curing is essential for effective coating curing and quality. Excessively high temperatures may cause coating burn-off or discoloration, while excessively low temperatures may lead to incomplete curing. Therefore, finding a synergistic curing speed and temperature that allows for rapid heat absorption and uniform heating of all parts of the stator bar insulating coating, achieving rapid and uniform curing of the coating film while avoiding wrinkling or orange peel effects caused by air convection, is critical.

[0006] Chinese patent publication number CN109107858A, filed on August 31, 2018, discloses a method for curing a coating. This method involves forming a curing agent layer on the substrate surface, then forming a base liquid layer within the curing agent layer, followed by curing to obtain a cured coating. This eliminates the need to mix the curing agent into the base liquid, effectively improving the long-term storage and use of the base liquid and increasing its utilization rate. However, this method requires the use of a curing agent and necessitates placing the prepared curing liquid on the substrate surface to form a curing liquid layer. The curing process is relatively complex, and the base liquid needs to be cured after the curing liquid layer dries, resulting in a long overall time requirement.

[0007] Chinese patent CN104827613A, filed on May 13, 2015, discloses a low-cost, rapid curing method for composite materials. This method uses a medium-frequency electromagnetic induction coil to directly heat and cure the composite material in a metal mold. Medium-frequency heating offers rapid temperature rise, good temperature field uniformity, precise control, and minimal temperature overshoot, significantly improving production efficiency while ensuring product quality. However, medium-frequency electromagnetic induction heating only heats the metal mold itself, while generator stator bars are wrapped with insulating tape, mica tape, etc. Therefore, the curing effect using the method described in this invention may be affected. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a curing method for insulating varnish coatings on bar wires. By selecting an infrared light band that matches the absorption wavelength of the coating and coordinating the temperature range suitable for coating curing, the method achieves rapid curing of the varnish film and ensures uniform curing effect on the varnish film surface.

[0009] The technical solution of the present invention is as follows:

[0010] The purpose of this invention is to provide a curing method for insulating varnish coatings on stator bars. The curing method controls the thickness and number of times the insulating varnish coating is applied to the surface of the generator stator bars, and uses infrared light-temperature gradient synergistic curing to uniformly dry the coating, thereby achieving rapid curing and drying of the insulating varnish coating.

[0011] Furthermore, the insulating varnish coating comprises low-resistivity varnish, high-resistivity varnish, and red ceramic varnish applied sequentially.

[0012] Furthermore, the thickness of the paint film applied each time for the low-resistivity paint, high-resistivity paint, and red porcelain paint is 50 μm.

[0013] Furthermore, the low-resistivity paint is applied once; the high-resistivity paint is applied three times; and the red porcelain paint is applied twice.

[0014] Furthermore, the low-resistivity paint infrared light-temperature gradient synergistic curing method is characterized by:

[0015] Curing time was 60 seconds in the 6.8 μm infrared band at 150 °C for 30 seconds; curing time was 15 seconds in the 6.5 μm infrared band at 170 °C for 15 seconds; and curing time was 15 seconds in the 6.2 μm infrared band at 190 °C for 15 seconds, for a total curing time of 60 seconds.

[0016] Furthermore, the high-resistivity paint infrared light-temperature gradient synergistic curing method is characterized by:

[0017] Curing time was 30 seconds at 140°C in the 7.0μm infrared band; 15 seconds at 160°C in the 6.7μm infrared band; and 15 seconds at 190°C in the 6.2μm infrared band, for a total curing time of 60 seconds.

[0018] Furthermore, the infrared light-temperature gradient synergistic curing method of the red porcelain paint is characterized by:

[0019] Curing time was 60 seconds in the 6.8 μm infrared band at 150 °C for 30 seconds; curing time was 15 seconds in the 6.5 μm infrared band at 170 °C for 15 seconds; and curing time was 15 seconds in the 6.2 μm infrared band at 190 °C for 15 seconds, for a total curing time of 60 seconds.

[0020] Furthermore, curing is performed using an infrared heating curing oven, which includes:

[0021] The furnace body has an clearance slit on its top along its length.

[0022] An infrared radiation source, wherein the infrared radiation source is installed on the inner side wall of the furnace body;

[0023] A translation component is used to move a steel cable along the trajectory of the avoidance joint. The lower end of the steel cable passes through the avoidance joint and extends into the furnace body. The lower end of the steel cable is used to install a wire rod.

[0024] Furthermore, an insulation layer is provided on the outside of the furnace body.

[0025] Furthermore, the infrared radiation source comprises multiple silicon carbide heating plates connected in parallel, which are then connected in sequence to a temperature control box and an electrical meter box; the silicon carbide heating plates maintain a constant distance of 50mm from the surface of the wire rod during the curing process.

[0026] Furthermore, the silicon carbide heating plate has dimensions of 200mm in length, 300mm in width, and 20mm in thickness.

[0027] Furthermore, the silicon carbide heating plate maintains a constant distance of 50 mm from the surface of the stator bar during the curing process.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. This invention addresses the surface structure and materials of generator stator bars, and for the first time discloses a novel curing method for insulating varnish coatings on the surface of generator stator bars. By selecting appropriate curing speed, infrared radiation wavelength, and curing temperature, an innovative infrared light-temperature gradient synergistic curing method is proposed. After drying through various gradients, the generator stator bars coated with insulating varnish can achieve both rapid curing and uniform curing effects, without the need for a curing agent, effectively avoiding the problem of poor varnish film curing quality caused by overheating or overcooling.

[0030] 2. This invention is the first to design an infrared light-temperature gradient synergistic curing method comprising three stages. In the first stage, the main solvent evaporates, causing the solvent in the coating to gradually evaporate, the fluidity of the coating to gradually decrease, and the surface of the coating to gradually dry, forming a solid film, but still containing a certain amount of solvent. In the second stage, the interior of the coating gradually dries, and the polymer in the coating undergoes cross-linking or chain elongation reactions, making the intermolecular bonding of the coating more compact. At the same time, the fillers, additives, and other components in the coating will gradually arrange and combine during the drying process to form a denser structure. In the third stage, the polymer reaction is completed, and the physical and chemical properties of the coating reach their optimal state, making the coating strong, durable, and possessing the required insulation properties.

[0031] 3. This invention utilizes a silicon carbide infrared heating plate to emit extremely strong infrared radiation to directly irradiate the generator stator bars. Simultaneously, it achieves synergistic curing of the curing conditions within each gradient using infrared light and temperature gradients. This allows for rapid heating and curing of the stator bar surface, avoiding the drawbacks of uneven coating curing, long curing time, strict curing conditions, and constraints imposed by irregularly shaped components during room temperature curing and convection heating curing. This is beneficial for improving the electrical and mechanical properties of the insulating varnish film and reducing the impact of stator bar insulation performance on generator reliability and service life.

[0032] Figure Labels

[0033] Figure 1 This is a front view of the infrared heating curing oven in Example 2;

[0034] Figure 2 This is a side cross-sectional view of the infrared heating curing oven in Example 2.

[0035] The reference numerals in the figure are as follows:

[0036] 1. Furnace body; 11. Circumvention joint; 12. Insulation layer; 13. Furnace door; 2. Translation component; 3. Wire rod; 4. Steel cable; 5. Infrared radiation source. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0039] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0040] In the quantitative experiments in the following examples, three replicate experiments were set up, and the average value of the results was taken.

[0041] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0042] Example 1

[0043] This embodiment provides a curing method for insulating varnish coatings on wire rods, the specific steps of which are as follows:

[0044] The stator bars are the stator bars of the generator.

[0045] S1. A low-resistivity paint coating is uniformly applied to the stator bars of the generator, with a coating thickness of 50μm. An industrial heating device is used as an infrared radiation source 5 to perform infrared light-temperature gradient synergistic curing on the low-resistivity paint coating. Specifically, it is cured for 30s at 150℃ in the 6.8μm infrared band; cured for 15s at 170℃ in the 6.5μm infrared band; and cured for 15s at 190℃ in the 6.2μm infrared band, for a total curing time of 60s.

[0046] S2. Three coats of high-resistivity varnish are applied to the stator bars coated with low-resistivity varnish, each coat having a film thickness of 50 μm. After each coat is applied, an industrial heating device is used as an infrared radiation source 5 to perform infrared light-temperature gradient synergistic curing on the high-resistivity varnish coating. Specifically, the curing is performed as follows: 30 s at 140℃ in the 7.0 μm infrared band; 15 s at 160℃ in the 6.7 μm infrared band; and 15 s at 190℃ in the 6.2 μm infrared band, for a total curing time of 60 s.

[0047] S3. Two coats of red enamel coating are applied to the stator bars coated with low-resistivity and high-resistivity enamel, with each coat having a film thickness of 50 μm. After each coat is applied, an industrial heating device is used as an infrared radiation source 5 to perform infrared light-temperature gradient synergistic curing on the red enamel coating. Specifically, the curing is performed as follows: 30 s at 150°C in the 6.8 μm infrared band; 15 s at 170°C in the 6.5 μm infrared band; and 15 s at 190°C in the 6.2 μm infrared band, for a total curing time of 60 s.

[0048] S4. Let the above-mentioned gradient-cured stator bar stand for 20 minutes to obtain a stator bar with a uniform insulating varnish coating.

[0049] The stator wire rod varnish film prepared by the curing method described in Example 1 dries rapidly as a whole, and the surface of the varnish film is free of bubbles, bulges, and peeling.

[0050] Comparative Example 1

[0051] This embodiment provides a method for curing the insulating varnish coating on generator stator bars, the specific steps of which are as follows:

[0052] S1. A low-resistivity paint coating is uniformly applied to the stator bars of the generator. The coating film thickness is 50μm. The silicon carbide heating plate is used as the infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity paint coating. Specifically, it is cured for 5 minutes at 170℃ in the 6.5μm infrared band.

[0053] S2. Three high-resistivity paint coatings are applied to the stator bar coated with low-resistivity paint, with a paint film thickness of 50μm. The silicon carbide heating plate is used as the infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity paint coating. Specifically, it is cured for 6 minutes at 170℃ in the 6.5μm infrared band.

[0054] S3. Apply two coats of red porcelain enamel coating to the stator bar coated with low-resistivity enamel and high-resistivity enamel, with a coating thickness of 50μm. Use a silicon carbide heating plate as an infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity enamel coating. Specifically, cure for 5 minutes at 170℃ in the 6.5μm infrared band.

[0055] S4. Let the cured stator bar stand for 20 minutes to obtain a stator bar with an insulating varnish coating.

[0056] Compared with Example 1, the insulating varnish coating on the stator bar surface failed to reach surface dryness, and the varnish film was damaged. With continued extension of time, the surface of the high-resistivity varnish film was relatively dry, but it was still sticky.

[0057] Comparative Example 2

[0058] This embodiment provides a method for curing the insulating varnish coating on generator stator bars, the specific steps of which are as follows:

[0059] S1. A low-resistivity paint coating is uniformly applied to the stator bars of the generator. The coating film thickness is 50μm. The silicon carbide heating plate is used as the infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity paint coating. Specifically, it is cured for 4 minutes at 190℃ in the 6.2μm infrared band.

[0060] S2. Three high-resistivity paint coatings are applied to the stator bar coated with low-resistivity paint, with a paint film thickness of 50μm. The silicon carbide heating plate is used as the infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity paint coating. Specifically, it is cured for 5 minutes at 190℃ in the 6.2μm infrared band.

[0061] S3. Apply two coats of red porcelain enamel to the stator bar coated with low-resistivity enamel and high-resistivity enamel, with a coating thickness of 50μm. Use a silicon carbide heating plate as an infrared radiation source 5 to perform infrared light-temperature synergistic curing on the low-resistivity enamel coating. Specifically, it is cured for 4 minutes at 190℃ in the 6.2μm infrared band.

[0062] S4. Let the cured stator bar stand for 20 minutes to obtain a stator bar with an insulating varnish coating.

[0063] Compared with Example 2, the surface of the insulating varnish coating on the stator bar has wrinkling and orange peel phenomena.

[0064] Performance testing

[0065] 1. Adhesion test

[0066] The stator bars with surface-cured insulating varnish coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to adhesion tests according to GB-T 9286-1998 "Cross-cut Test for Paint and Varnish Films". Specific requirements are as follows: A cross-cut tester with a multi-blade cutter having six cutting faces was prepared as the testing tool, with cutter gaps of 1mm, 2mm, and 3mm (the cutter heads can be replaced). The sample was coated onto a template, and after drying, the cross-cut tester was pulled parallel to the substrate for 3-4cm (cutting through the varnish film to the substrate). Then, the same method was used perpendicularly to the previous step to form many small squares.

[0067] Table 1 Adhesion test results

[0068] type Adhesion Example 1 Level 1 Comparative Example 1 Level 3 Comparative Example 2 Level 3

[0069] As shown in Table 1, the small squares of the stator bar with the surface cured with insulating varnish coating prepared in Example 1 only had a small amount of coating peeling off at the intersection of the cuts, and the adhesion was grade 1, which was significantly better than the grade 3 adhesion shown by the stator bars prepared in Comparative Example 1 and Comparative Example 2. This indicates that the curing method provided by the present invention enables the insulating varnish coating of the stator bar to have good adhesion performance and can better meet specific usage requirements.

[0070] 2. Surface resistivity test

[0071] The stator bars with surface-cured insulating varnish coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to surface resistivity tests. According to GB / T 1401-2006, Test Method for Surface Resistivity of Solid Insulating Materials, the uniformly stirred anti-corrosion varnish was applied to the insulating board, and after complete infrared curing, it was cooled to room temperature. Surface resistance was measured using a multimeter, with three points measured for each sample, and the average value was taken as the surface resistance.

[0072] Table 2 Surface resistivity test results

[0073] type Surface resistivity (Ω) Example 1 <![CDATA[6.50×10 10 ]]> Comparative Example 1 <![CDATA[4.55×10 10 ]]> Comparative Example 2 <![CDATA[4.85×10 10 ]]>

[0074] As shown in Table 2, the average surface resistivity of the stator bar with the insulating varnish coating cured on the surface obtained in Example 1 is significantly improved compared with the stator bars obtained in Comparative Example 1 and Comparative Example 2, which proves that the curing method provided by the present invention can enable the insulating varnish coating of the stator bar to better perform its insulating properties.

[0075] 3. Volume resistivity test

[0076] The stator bars with surface-cured insulating varnish coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to volume resistivity tests. According to GB / T 1401-2006 Test Method for Volume Resistivity of Solid Insulating Materials, a conductive adhesive was prepared in a certain proportion. A circular aluminum foil sample with a diameter of 20 mm was used as an electrode. The electrode and the sample to be tested were bonded together with the conductive adhesive under a stable pressure. The volume resistivity of the varnish film with different thicknesses was tested using a three-electrode system insulating megohmmeter.

[0077] Table 3. Volume resistivity test results

[0078] type Volume resistivity (Ω·m) Example 1 <![CDATA[4.12×10 16 ]]> Comparative Example 1 <![CDATA[2.12×10 16 ]]> Comparative Example 2 <![CDATA[1.86×10 16 ]]>

[0079] As shown in Table 3, the volume resistivity of the stator bar with the surface cured with insulating varnish coating obtained in Example 1 is significantly improved compared with the stator bars obtained in Comparative Example 1 and Comparative Example 2, which proves that the curing method provided by the present invention can enable the insulating varnish coating of the stator bar to better perform its insulating properties.

[0080] 4. Heat resistance test

[0081] The stator bars with surface-cured insulating varnish coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to heat resistance tests according to standard GB / T 11026.1-2016, and the methods are as follows:

[0082] a) Prepare an appropriate amount of sample for performance measurement;

[0083] b) Group the samples and age them at the high temperature levels shown in Table 4, i.e., continuously for one corresponding cycle. Between the cycle tests, restore the samples to room temperature or another standard temperature.

[0084] c) Conduct diagnostic tests on the samples to reveal the degree of aging;

[0085] d) Extend the continuous heat exposure until the specified endpoint and calculate the mass loss rate for each group.

[0086] Table 4 Results of Heat Resistance Test

[0087]

[0088] As shown in Table 4, the stator bar with an insulating varnish coating cured on the surface prepared in Example 1 had a low mass loss rate in the three cycles of 280℃-24h, 260℃-72h, and 240℃-168h. Compared with the stator bars prepared in Comparative Example 1 and Comparative Example 2, the heat resistance performance was significantly improved.

[0089] Example 2:

[0090] like Figure 1-2 As shown:

[0091] The furnace body 1 is 10-200m long, with a square or rectangular cross-section and a side length of 0.5-5m. The furnace body 1 is made of iron, steel or stainless steel sheets and has a hollow cuboid structure. The furnace body 1 has openings at both ends and is equipped with furnace doors 13 with heat insulation layers to maintain the furnace temperature. A clearance joint 11 with a width of 1-10cm is provided between the left and right ends of the top of the furnace body 1 to allow the steel cable 4 of the hoisting rod 3 to move. The two ends of the clearance joint 11 are connected to the openings at the left and right ends of the furnace body 1 to facilitate the entry and exit of the steel cable 4.

[0092] Infrared radiation sources 5 are installed on each inner surface of the furnace body 1. Each infrared radiation source 5 comprises multiple parallel silicon carbide heating plates, which are then connected in sequence to a temperature control box and an electrical meter box. During the curing process, the silicon carbide heating plates maintain a constant distance of 50mm from the surface of the wire rod 3, allowing infrared radiation to reach all locations within the furnace body 1. The infrared radiation sources 5 are composed of plate-shaped infrared devices, preferably silicon carbide heating ceramic plates, with a power of 0.3–5 kW per plate. Infrared heating does not require a heat transfer medium (such as air, water, or oil) but directly heats the material through electromagnetic radiation, thus reducing heat absorption and waste by the medium. Molecules absorb infrared radiation and vibrate to generate heat, allowing materials of various shapes to be uniformly heated within seconds, rather than through conduction from the outside in via a medium.

[0093] A heat insulation layer 12 with a thickness of 2-10cm is provided on the outside of the furnace body 1;

[0094] A translation component 2 is installed directly above the clearance joint 11 of the furnace body 1. The translation component 2 includes a guide rail and a movable trolley that can move on the guide rail. The movable trolley has its own power system to move on the guide rail, or a power system is installed on the guide rail to drive the movable trolley to move. This is existing technology and will not be described in detail. The guide rail is 0.2 to 3 meters away from the upper surface of the furnace body. Two or more steel cables 4 are installed at the bottom of the movable trolley. The steel cables 4 hang freely so that their lower ends pass through the clearance joint 11 and extend into the interior of the furnace body 1.

[0095] A PLC panel is installed on the outer side of the furnace body 1, which integrates the control of infrared radiation source 5, moving trolley, etc. It can adjust the infrared band, temperature and moving trolley speed according to the process requirements of low-resistivity paint, high-resistivity paint and red porcelain paint.

[0096] To facilitate the movement of the wire rod 3, the length of the guide rail is 2 to 10 meters longer than the length of the furnace body 1.

[0097] The wire rod 3 is suspended from the lower end of the steel cable 4 by an external clamp. The external clamp is an existing product and is not a key design feature of this solution, so it will not be described in detail. The wire rod 3 enters and exits the furnace body 1 through openings at both ends of the furnace body 1.

[0098] The workpiece can be moved by the translation component, which is conducive to continuous production and can also solve the problem of large footprint during the curing process.

[0099] Working principle:

[0100] 1) Suspend the wire rod 3 from the lower end of the steel cable 4 outside the furnace body 1, preferably with the wire rod 3 located in the center of the cross section of the furnace body 1.

[0101] 2) Set parameters such as infrared radiation source 5 and the moving speed of the moving trolley on the PLC panel.

[0102] 3) Open the feed door (furnace door 13) on the right side of furnace body 1, and close furnace door 13 after the wire rod 3 enters.

[0103] 4) The workpiece moves within furnace body 1 and gradually completes the curing process.

[0104] 5) Open the discharge door (furnace door 13) on the left side of furnace body 1 and remove the wire rod 3.

[0105] 6) Turn off the computer after completion.

[0106] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A curing method for insulating varnish coatings on wire rods, characterized in that, By controlling the thickness and number of times the insulating varnish coating is applied to the surface of the bar, and by uniformly drying the coating using an infrared light-temperature gradient synergistic curing method, the rapid curing and drying of the insulating varnish coating is achieved. The insulating varnish coating is composed of low-resistivity varnish, high-resistivity varnish, and red ceramic varnish applied sequentially. The low-resistivity paint infrared light-temperature gradient synergistic curing method is characterized by: Curing was performed at 150°C for 30 seconds in the 6.8μm infrared band; at 170°C for 15 seconds in the 6.5μm infrared band; and at 190°C for 15 seconds in the 6.2μm infrared band, for a total curing time of 60 seconds. The infrared light-temperature gradient synergistic curing method of the high-resistivity paint is characterized by: Curing was performed at 7.0 μm infrared band and 140 °C for 30 s; at 6.7 μm infrared band and 160 °C for 15 s; and at 6.2 μm infrared band and 190 °C for 15 s, for a total curing time of 60 s. The infrared light-temperature gradient synergistic curing method of the red porcelain paint is as follows: Curing time was 60 seconds in the 6.8 μm infrared band at 150 °C for 30 seconds; curing time was 15 seconds in the 6.5 μm infrared band at 170 °C for 15 seconds; and curing time was 15 seconds in the 6.2 μm infrared band at 190 °C for 15 seconds, for a total curing time of 60 seconds.

2. The curing method for insulating varnish coatings on wire rods as described in claim 1, characterized in that, The thickness of the paint film applied each time for the low-resistivity paint, high-resistivity paint, and red porcelain paint is 50μm.

3. The curing method for insulating varnish coatings on wire rods as described in claim 1, characterized in that, The low-resistivity paint is applied once; the high-resistivity paint is applied three times; and the red porcelain paint is applied twice.

4. The curing method for insulating varnish coatings on wire rods as described in claim 1, characterized in that, Heating and curing are performed using an infrared heating curing oven, the infrared heating curing oven comprising: Furnace body (1), the top of the furnace body (1) is provided with a clearance slit (11) along its length direction; Infrared radiation source (5), the infrared radiation source (5) is installed on the inner side wall of the furnace body (1); Translation component (2), the translation component (2) is used to drive the steel cable (4) to move along the trajectory of the avoidance joint (11), the lower end of the steel cable (4) passes through the avoidance joint (11) and extends into the furnace body (1), the lower end of the steel cable (4) is used to install the wire rod.

5. The curing method for insulating varnish coatings on wire rods as described in claim 4, characterized in that: The furnace body (1) is provided with an insulation layer (12) on the outside.

6. The curing method for insulating varnish coatings on wire rods as described in claim 4, characterized in that, The infrared radiation source (5) includes multiple silicon carbide heating plates connected in parallel; the silicon carbide heating plates maintain a constant distance of 50 mm from the surface of the wire rod during the curing process.

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