Preparation method of corona-resistant enameled copper round wire for scroll compressor and copper round wire

Abstract

The invention relates to the technical field of enameled wire preparation, and in particular to a method for preparing a corona-resistant enameled copper round wire specially used for a scroll compressor and a copper round wire. The invention comprises the following steps: annealing a round wire base material to obtain a primer wire to be coated; coating a primer on the surface of the primer wire to be coated to obtain the enameled copper round wire; judging whether the enameled copper round wire is bitten at the bottom according to a thermal infrared image of the primer; wrapping the enameled copper round wire outside and baking and sintering to obtain a wrapped enameled wire; coating a topcoat on the surface of the wrapped enameled wire and baking and curing to obtain a corona-resistant enameled copper round wire; and dividing curing into two steps of pre-low-temperature curing and high-temperature curing after the primer is coated and fixed, the problem of stratification and disconnection between paint films is solved, and not only can the paint film be formed quickly, but also the various properties of the paint film, such as electrical conductivity, corona resistance and voltage withstand, can be ultimately guaranteed, thereby greatly improving the accuracy of identifying the bitten at the bottom phenomenon, and avoiding the bitten at the bottom of the primer through the paint film wrapped with an intermediate layer.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wire preparation, and in particular to a method for preparing a corona-resistant enameled copper round wire specially used for a scroll compressor and the copper round wire. Background Art

[0002] At present, the variable frequency motors of scroll compressors are increasingly required to be small in size and high in power, so the cross-sectional area of ​​the cable also needs to be reduced accordingly. The winding in the scroll compressor needs to be very tight, which increases the stretching and bending of the enameled wire, causing the paint film to be easily damaged. In addition, the enameled wire in the motor is immersed in oil or water for cooling, so it needs to be resistant to oil immersion cold and heat shock. The existing motor enameled wire will carbonize and fail in a short time under the oil immersion cold and heat shock environment. Existing technologies, such as the Chinese invention patent with announcement number CN111627618B, a production and processing process for enameled wire for automotive oil-cooled drive motors, uses three different types of paint for combined coating, and the bottom layer is painted with high-adhesion polyamide-imide paint, the middle layer is painted with corona-resistant polyimide paint, and the top layer is painted with oil-resistant and hydrolysis-resistant polyamide-imide paint to allow each of them to play their respective advantages and make up for their shortcomings, and finally prepare an enameled wire with comprehensive winding resistance and strong resistance to oil immersion cold and heat shock. However, its process is complicated and has a three-layer paint structure. If In the process of applying any layer, the topcoat film is too thick, swelling the lower primer, causing the primer coating to wrinkle and bite the bottom (when applying the second topcoat, the newly applied paint bites the previous coating from the substrate. When this happens, the coating expands, shifts, shrinks, wrinkles, bulges, and even loses adhesion and falls off). Even the lower primer at any position of the enameled wire has a bite problem, especially the first layer of primer. The thin position on one side of the bite position will make the paint film have a certain air permeability, causing the copper conductor to oxidize and cause the surface of the enameled wire to become flowery. The thick position on one side of the bite position may make the cross-linking reaction insufficient and the adhesion of the paint film decrease, and the tip shrinks after being pulled off. The thin film of the subsequent topcoat is not conducive to the scratch resistance of the enameled wire; most enameled wires need to be fully baked every time the paint is applied to make the paint film well cured. If each coat of paint is fully cured during baking, the paint films of each coat will be delaminated and cannot form a solid whole. The strength of the paint film is very poor and the scratch resistance is unqualified. This is because the primer is fully cured into an infusible substance after baking, and its poor adhesion causes the paint film to delaminate. The more times the primer is applied, the more obvious this problem is. The number of coats of paint directly affects the appearance and properties such as pinholes. The scratch resistance, tensile and bending mechanical properties of the enameled wire are poor. Increasing the number of coats of paint will cause the cross-sectional area of ​​the enameled wire to be too large, making the prepared enameled wire unable to be used in the variable frequency motor of a miniaturized scroll compressor. Summary of the invention

[0003] The purpose of the present invention is to propose a method for preparing a corona-resistant enameled copper round wire specially used for a scroll compressor and a copper round wire, so as to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0004] In order to achieve the above object, according to one aspect of the present invention, a method for preparing corona-resistant enameled copper round wire for scroll compressor is provided, the method comprising the following steps:

[0005] S100, annealing the round wire base material to obtain a primer-coated wire;

[0006] S200, coating a primer on the surface of the primer-coated wire and curing at low temperature to obtain an enameled copper round wire, and after the total number of times of coating the primer and curing at low temperature is greater than or equal to two times, preheating the enameled copper round wire and obtaining a thermal infrared image of the enameled copper round wire;

[0007] S300, judging whether the enameled copper round wire is bitten according to the thermal infrared image, if yes, the enameled copper round wire is recorded as a wire to be coated with primer and the process goes to step S200; if no, the enameled copper round wire is cured at high temperature to form a paint film and the process goes to step S400;

[0008] S400, a corona-resistant polyimide film is wrapped around an enameled round copper wire and then baked and sintered to obtain a wrapped enameled wire;

[0009] S500, a topcoat is applied on the surface of the wound enameled wire and the wire is baked and cured to obtain a corona-resistant enameled round copper wire.

[0010] Furthermore, in S100, the method of annealing the round wire base material to obtain the primer wire to be coated is specifically: annealing the round wire base material in an annealing furnace at a speed of 30 to 60 m / min, the annealing temperature is 450 to 700°C, the tensile stress is removed by stewing in the annealing furnace, the round wire base material is softened, and the lubricant, oil stains, etc. remaining on the surface of the round wire base material during the stretching process are removed.

[0011] Further, in S100, during the annealing process, after the round wire base material passes through the annealing furnace, the round wire base material is introduced into an annealing water tank for cooling and annealing, and the annealing water tank includes deionized water.

[0012] Further, in S100, the round wire base material is a copper core conductor having a wire diameter of any one of 0.1 mm, 0.25 mm, 0.5 mm, 0.75 mm, 1.0 mm, 1.25 mm, 1.5 mm, 2.5 mm, 4 mm, 6 mm, and 10 mm.

[0013] Since the primer is generally made of polyamide-imide, if the paint films on the enameled wire are layered and cannot form a solid whole, the strength of the paint film is very poor and the scratch resistance is unqualified if the paint is directly layered. Therefore, since the molecular chain segments of polyamide-imide are short when it is cured below 200°C, it mainly relies on the hydrogen bonding between the chain segments to cure into a film, and the film is brittle and has poor thermal stability; see reference: Li Li, Qi Yuhong, Zhang Yan, et al. Effect of curing temperature on the structure and thermal stability of polyamide-imide coating [J]. Polymer Materials Science and Engineering, 2015, 31(8):5, using this characteristic, if there is a problem that the paint films of each painting are delaminated and cannot form a solid whole, the polyamide-imide paint films of each painting on the enameled wire at a temperature below 200°C are very likely to have a bottom biting problem that can be identified by infrared thermal imaging due to the high brittleness of the cured paint films; if the bottom biting problem does not occur after painting, the corresponding paint films will be delaminated to form a solid whole, and then high-temperature curing again can obtain an enameled wire with good performance and a solid whole; if the bottom biting problem occurs after painting, it is obvious that there are gaps between the paint films, which will not only affect the bending performance, but also have a significant impact on the performance such as corona resistance and withstand voltage. Therefore, the present application solves the problem of delamination and disconnection between the paint films by dividing the curing into two steps: pre-low temperature curing and high temperature curing after the primer is applied and set, which can not only quickly form a paint film, but also ultimately ensure the various properties of the paint film such as conductivity, corona resistance and withstand voltage. The specific method is as follows:

[0014] Further, in S200, the method of applying a primer on the surface of the primer-coated wire and curing at low temperature to obtain the enameled copper round wire is specifically as follows: performing the operation of applying a primer and curing at low temperature: uniformly applying the primer on the surface of the primer-coated wire, and after painting, performing low-temperature baking and curing on the enameled copper round wire to form a paint film;

[0015] If the total number of primer coating and low temperature curing operations is less than 2 times, it is performed twice. If the total number is greater than or equal to 2 times, the primer coating and low temperature baking curing operations are performed only once.

[0016] The low-temperature baking and curing temperature is 150-200° C., the baking speed is 3-300 m / min, and the primer is a high-adhesion polyamide-imide paint.

[0017] Furthermore, in S200, the thickness of each paint film is uniform, ranging from 0.010 to 0.015 mm.

[0018] Furthermore, the high-adhesion polyamide-imide paint is 200-grade polyamide-imide.

[0019] Furthermore, in S200, the method for obtaining the thermal infrared image of the enameled round copper wire is: obtaining the thermal infrared image of the primer on the surface of the enameled round copper wire by a high-precision infrared thermal imager.

[0020] Furthermore, the enameled round copper wire is preheated to heat the enameled round copper wire to 50-200° C. (generally set to be lower than the glass transition temperature of 250° C.).

[0021] Further, in S300, the method for judging whether the enameled round copper wire has bitten bottom according to the thermal infrared image includes:

[0022] The acquisition frequency is 1 to 2 images per second, and the length of the enameled round copper wire is 0.5m or 1m;

[0023] Mark the area of ​​the enameled copper round wire on the thermal infrared image as the area of ​​interest; perform edge detection on the area of ​​interest to obtain multiple edge lines, and use the edge lines to divide each area of ​​interest to obtain multiple enameled areas; the enameled area where the average temperature value of each point in the enameled area is less than the average temperature value of each point in the area of ​​interest is recorded as an abnormal enameled area; (Since the thinner the thickness and the larger the surface area, the faster the heat transfer speed. Since the bottom biting occurs from the second application of the primer, the coating at the bottom biting position will expand, shift, shrink, wrinkle, bulge, or even lose adhesion and fall off. The surface area of ​​the coating at the bottom biting position increases or the thickness becomes thinner, so the heat dissipation is faster than other areas. Mark these suspected bottom biting areas as abnormal enameled areas; Note: The abnormal enameled area does not necessarily have bottom biting. The area may also be thin in thickness but no bottom biting occurs, or the area is composed of some tiny but no negative micro-bubbles or expansion caused by paint materials, so it needs to be identified by subsequent methods);

[0024] The abnormal paint area with the highest average temperature value is marked as the heat-out area; the abnormal paint area with the lowest average temperature value is marked as the heat-in area; (If the paint layers are bitten, the newly applied paint near the bitten area is generally roughly the same. Since painting is a linear and continuous process, the bitten areas are separated by the first layer of paint bitten. Therefore, although the arrangement between the bitten areas is separated, it is generally consistent with or opposite to the direction of primer application; since heat is transferred from the high-temperature area to the low-temperature area, the heat transfer between the bitten areas is generally from the high-temperature area to the relatively low-temperature area); the point with the highest temperature value on the edge line of the heat-out area is UpPoint, and the point with the lowest temperature value on the edge line of the heat-in area is DoPoint; the direction from UpPoint to DoPoint is the heat transfer direction;

[0025] The abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-outlet area and the abnormal enameled area is recorded as the high heat transfer area HighA; the abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-inlet area and the abnormal enameled area is recorded as the low heat transfer area LowA;

[0026] The straight line passing through the point on the edge line of HighA closest to UpPoint and the point on the edge line of LowA closest to UpPoint is UpLine; the straight line passing through the point on the edge line of HighA closest to DoPoint and the point on the edge of LowA closest to DoPoint is DoLine; in the region of interest, the region between UpLine and DoLine is the heat transfer region ContinuA;

[0027] Starting from the position of the heat outlet area, each abnormal enameled area inside ContinuA is searched in sequence along the direction of heat transfer. When all abnormal enameled areas meet the heat transfer continuity condition, it is determined that the enameled copper round wire has bitten the bottom;

[0028] Among them, the heat transfer continuity condition is: HeatC(AbnA(i-1))≥HeatC(AbnA(i)) and HeatC(AbnA(i))≥HeatC(AbnA(i+1)), where AbnA(i) is the i-th abnormal enameled area inside ContinuA along the direction of heat transfer from the heat outlet area, and i is the sequence number; the HeatC() function takes the average temperature value of all points on the edge of the abnormal enameled area; (except that i is the first and last, all abnormal enameled areas are judged for heat transfer continuity conditions);

[0029] (The average temperature value of the above abnormal enameled area on the edge line of the adjacent area starts from the position of the heat outlet area along the direction of heat transfer. The i-th abnormal enameled area inside ContinuA sometimes cannot fully show the heat conduction trend, because sometimes the area may also be thin but without bottom biting, or the area is composed of some tiny bubbles but without negative effects, or the heat transfer of the abnormal enameled area caused by the expansion of the paint material is not from high to low in sequence due to the occurrence of local abnormal enameled areas, and there is a discontinuity in the middle. Therefore, the present application proposes the following calculation method of the thermal conductivity coefficient value to determine the heat transfer continuity in this case);

[0030] Alternatively, the heat transfer continuity condition is:

[0031] TH(AbnA(i-1))≥TH(AbnA(i))≥TH(AbnA(i+1));

[0032] Among them, the TH(AbnA(i)) function is to take the thermal conductivity value of the i-th abnormal enameled area AbnA(i). The calculation method of the thermal conductivity value TH(AbnA(i)) of AbnA(i) is: the thermal conductivity value is the average value of the temperature values ​​of all points on the edge from the 1st to the i-th abnormal enameled area,

[0033] Alternatively, the thermal conductivity value TH(AbnA(i)) is calculated as:

[0034] ;

[0035] Wherein, j is a variable, HG(HighA,AbnA(j)) is the difference between the average temperature value of the high heat transfer area HighA and the average temperature value of each point on the edge of AbnA(j); LG(AbnA(j),LowA) is the difference between the average temperature value of the low heat transfer area LowA and the average temperature value of each point on the edge of AbnA(j); AbnA(j) is the jth abnormal enamel area inside ContinuA along the direction of heat transfer starting from the position of the heat outlet area;

[0036] Among them, HG (HighA, AbnA (j)) and LG (AbnA (j), LowA) can accurately show the difference in temperature values ​​between all abnormal enameled areas along the direction of heat transfer of the jth abnormal enameled area and the jth abnormal enameled area, and can show that intermittent heat transfer inertia is generated in the middle of the heat transfer direction of all abnormal enameled areas.

[0037] The average temperature value of the abnormal enameled area is the average value of the temperature values ​​corresponding to the positions of all points in the abnormal enameled area.

[0038] When all abnormal enameled areas meet the heat transfer continuity condition, it is judged that the enameled copper round wire has bitten the bottom; if any abnormal enameled area does not meet the heat transfer continuity condition, it is judged that the enameled copper round wire has not bitten the bottom.

[0039] Based on the natural characteristics of heat conduction, it is possible to accurately identify whether continuous heat transfer occurs in all abnormal enameled areas, thereby accurately judging whether the primer has truly bitten the bottom or whether it is a false identification problem caused by abnormal enameled areas where no bitten bottom has occurred. This greatly improves the accuracy of identifying the bitten bottom phenomenon and can reduce the number of primer coating times while ensuring cable performance, making it more suitable for use in miniaturized scroll compressors.

[0040] Preferably, the method for marking the area of ​​the enameled copper round wire on the thermal infrared image as the area of ​​interest is: binarizing the thermal infrared image to obtain a binary image, performing Hough line detection on the binary image to obtain straight lines in the binary image; and taking the area between the two longest straight lines as the area of ​​interest.

[0041] Further, in S300, the method of high-temperature curing the enameled copper round wire to form a paint film is as follows: after painting, the enameled copper round wire is baked and cured to form a paint film, the baking temperature of the high-temperature curing is 230-800°C, the baking speed is 30m / min, and the paint film is naturally cooled after being formed.

[0042] Furthermore, in S400, the method for obtaining the wrapped enameled wire by wrapping the corona-resistant polyimide film around the enameled round copper wire and baking and sintering the film is as follows: the corona-resistant polyimide film is wrapped around the enameled round copper wire in an overlapping manner with an overlap width of 50% or 2 / 3 of the overlap width, and after wrapping, the wrapped enameled wire is heated, baked and sintered at a temperature of 200 to 280° C. for 15 to 20 minutes to obtain the wrapped enameled wire.

[0043] Preferably, the corona-resistant polyimide film is a corona-resistant polyimide film coated with 0.025 mm to 0.040 mm polyperfluoroethylene-propylene resin on the surface.

[0044] Preferably, in S400, the wrapping is performed by a multi-head wrapping machine using an Omron CJ1W-MCH71 motion controller.

[0045] Further, in S500, the method for obtaining corona-resistant enameled copper round wire by coating the surface of the wrapped enameled wire with a topcoat and baking and curing the surface is as follows: after evenly coating the surface of the wrapped enameled wire with the topcoat, baking and curing the surface, the baking temperature is 200 to 800°C, and the baking speed is 3 to 300 m / min to obtain the corona-resistant enameled copper round wire; the topcoat is oil-resistant polyamide-imide paint, and the thickness of each coating of the topcoat is 0.010 mm.

[0046] Preferably, in S500, coating the surface of the enameled wire with a topcoat and baking and curing to obtain the corona-resistant enameled round copper wire is repeated 2 to 5 times.

[0047] Furthermore, the oil-resistant polyamide-imide paint is 220 grade polyamide-imide.

[0048] Preferably, the method further comprises: naturally cooling the prepared corona resistant enameled copper round wire, and then lubricating the surface of the corona resistant enameled copper round wire through an oil box; thereby reducing mechanical damage to the corona resistant enameled copper round wire caused by impact and friction during the next winding step, and avoiding damage to the topcoat of the corona resistant enameled copper round wire, resulting in a decrease in the insulation performance of the paint film.

[0049] Preferably, the method further comprises: using a wire take-up machine to roll up the corona-resistant enameled copper round wire.

[0050] Among them: the paint film thickness of the primer and topcoat after treatment in S200 and S500 is 0.060~0.200mm.

[0051] The present invention also provides a round copper wire, which is a corona-resistant enameled round copper wire prepared by the method for preparing a corona-resistant enameled round copper wire specially used for a scroll compressor according to the present invention.

[0052] As described above, the method for preparing corona-resistant enameled copper round wire for scroll compressors and the copper round wire described in the present invention have the following beneficial effects: by dividing the curing into two steps, namely, preliminary low-temperature curing and high-temperature curing after the primer is applied and fixed, the problem of stratification and disconnection between the paint films is solved, and not only can the paint film be formed quickly, but also the various properties of the paint film, such as electrical conductivity, corona resistance, and voltage tolerance, can be ultimately guaranteed; the natural characteristics of heat conduction are accurately used to identify whether continuous heat transfer occurs in all abnormal enameled areas, so as to accurately judge whether the primer is actually bitten or due to the phenomenon of undercutting. There is no false identification problem caused by abnormal lacquer areas where biting occurs, which greatly improves the accuracy of identifying the biting phenomenon. The paint film wrapped around the middle layer avoids the biting of the primer and can reduce the number of primer coatings while ensuring the performance of the cable. Unlike the traditional three-layer structure, the above effects result in fewer primer coatings (only 2 times are required for locations without biting on the primer), and the middle layer between the primer and the topcoat is wrapped and fired with a thin film, so the final cable's external paint layer thickness is smaller and the cable wire diameter is smaller, making it more suitable for use in miniaturized scroll compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The above and other features of the present invention will become more obvious by describing in detail the embodiments shown in the accompanying drawings. The same reference numerals in the accompanying drawings of the present invention represent the same or similar elements. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work. In the accompanying drawings:

[0054] Figure 1 Shown is a flow chart of a method for preparing corona-resistant enameled round copper wire specifically for scroll compressors. DETAILED DESCRIPTION

[0055] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0056] Example 1

[0057] like Figure 1 The flowchart of the method for preparing the corona-resistant enameled copper round wire for scroll compressor according to the present invention is shown below. Figure 1 The following describes a method for preparing a corona-resistant enameled round copper wire specifically for a scroll compressor according to an embodiment of the present invention.

[0058] S100, annealing the round wire base material to obtain a primer-coated wire;

[0059] S200, coating a primer on the surface of the primer-coated wire and curing at low temperature to obtain an enameled copper round wire, and after the total number of times of coating the primer and curing at low temperature is greater than or equal to two times, preheating the enameled copper round wire and obtaining a thermal infrared image of the enameled copper round wire;

[0060] S300, judging whether the enameled copper round wire is bitten according to the thermal infrared image, if yes, the enameled copper round wire is recorded as a wire to be coated with primer and the process goes to step S200; if no, the enameled copper round wire is cured at high temperature to form a paint film and the process goes to step S400;

[0061] S400, a corona-resistant polyimide film is wrapped around an enameled round copper wire and then baked and sintered to obtain a wrapped enameled wire;

[0062] S500, a topcoat is applied on the surface of the wound enameled wire and the wire is baked and cured to obtain a corona-resistant enameled round copper wire.

[0063] Further, in S100, the method of annealing the round wire base material to obtain the primer wire to be coated is specifically: annealing the round wire base material in an annealing furnace at a speed of 30 m / min and the annealing temperature is 450°C.

[0064] Further, in S100, during the annealing process, after the round wire base material passes through the annealing furnace, the round wire base material is introduced into an annealing water tank for cooling and annealing, and the annealing water tank includes deionized water.

[0065] Furthermore, in S100, the round wire base material is a copper core conductor.

[0066] Further, in S200, the method of applying a primer on the surface of the primer-coated wire and baking and curing to obtain the enameled copper round wire is specifically as follows: performing a primer-coating and low-temperature curing operation: uniformly applying the primer on the surface of the primer-coated wire, and after painting, baking and curing the enameled copper round wire at a low temperature to form a paint film;

[0067] If the total number of primer coating and low temperature curing operations is less than 2 times, it is performed twice. If the total number is greater than or equal to 2 times, the primer coating and low temperature baking curing operations are performed only once.

[0068] The low-temperature baking curing temperature is 170° C., the baking speed is 30 m / min, and the primer is naturally cooled after forming a paint film. The primer is 200-grade polyamide-imide.

[0069] Furthermore, in S200, the thickness of each paint film is uniform, and the thickness is 0.010 mm.

[0070] Furthermore, in S200, the method for obtaining the thermal infrared image of the enameled round copper wire is: obtaining the thermal infrared image of the primer on the surface of the enameled round copper wire by a high-precision infrared thermal imager.

[0071] Furthermore, the enameled round copper wire is preheated to 50°C.

[0072] Further, in S300, the method for judging whether the enameled round copper wire has bitten bottom according to the thermal infrared image includes:

[0073] The acquisition frequency is 2 images per second, and the length of the enameled copper round wire is 0.5 meters;

[0074] Marking the region of the enameled copper round wire on the thermal infrared image as the region of interest; performing edge detection on the region of interest to obtain multiple edge lines, and dividing each region of interest by the edge lines to obtain multiple enameled regions; and recording the enameled region whose average temperature value of each point in the enameled region is less than the average temperature value of each point in the region of interest as an abnormal enameled region;

[0075] The abnormal enameled area with the highest average temperature value is marked as the heat-out area; the abnormal enameled area with the lowest average temperature value is marked as the heat-in area; the point with the highest temperature value on the edge line of the heat-out area is UpPoint, and the point with the lowest temperature value on the edge line of the heat-in area is DoPoint; the direction from UpPoint to DoPoint is the heat transfer direction;

[0076] The abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-outlet area and the abnormal enameled area is recorded as the high heat transfer area HighA; the abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-inlet area and the abnormal enameled area is recorded as the low heat transfer area LowA;

[0077] The straight line passing through the point on the edge line of HighA closest to UpPoint and the point on the edge line of LowA closest to UpPoint is UpLine; the straight line passing through the point on the edge line of HighA closest to DoPoint and the point on the edge of LowA closest to DoPoint is DoLine; in the region of interest, the region between UpLine and DoLine is the heat transfer region ContinuA;

[0078] Starting from the position of the heat outlet area, each abnormal enameled area inside ContinuA is searched in sequence along the direction of heat transfer. When all abnormal enameled areas meet the heat transfer continuity condition, it is determined that the enameled copper round wire has bitten the bottom;

[0079] Among them, the heat transfer continuity condition is: HeatC(AbnA(i-1))≥HeatC(AbnA(i)) and HeatC(AbnA(i))≥HeatC(AbnA(i+1)), where AbnA(i) is the i-th abnormal enameled area inside ContinuA along the direction of heat transfer starting from the position of the heat outlet area, and i is the serial number; the HeatC() function takes the average temperature value of each point on the edge of the abnormal enameled area; except for the first and last i, all abnormal enameled areas are subject to heat transfer continuity condition judgment.

[0080] The average temperature value of the abnormal enameled area is the average value of the temperature values ​​corresponding to all point positions in the abnormal enameled area.

[0081] Further, in S300, the method of high-temperature curing the enameled copper round wire to form a paint film is as follows: after painting, the enameled copper round wire is baked and cured to form a paint film, the baking temperature of the high-temperature curing is 270°C, the baking speed is 30m / min, and the paint film is naturally cooled after being formed.

[0082] Furthermore, in S400, the method for obtaining the wrapped enameled wire by wrapping the corona-resistant polyimide film around the enameled round copper wire and baking and sintering the film is as follows: the corona-resistant polyimide film is wrapped around the enameled round copper wire with an overlap width of 50% and an overlapping wrapping method, and after wrapping, the wrapped enameled wire is heated, baked and sintered at a temperature of 270°C for 15 minutes to obtain the wrapped enameled wire, and then cooled naturally.

[0083] Wherein, the corona-resistant polyimide film is a corona-resistant polyimide film with 0.025 mm polyperfluoroethylene-propylene resin coated on the surface.

[0084] Among them, in S400, the wrapping is performed by a multi-head wrapping machine using an Omron CJ1W-MCH71 motion controller.

[0085] Further, in S500, the method for preparing corona-resistant enameled copper round wire by coating the surface of the wrapped enameled wire with topcoat and baking and curing the surface of the wrapped enameled wire is as follows: after evenly coating the surface of the wrapped enameled wire with topcoat, baking and curing the surface of the wrapped enameled wire is performed, the baking temperature is 270°C, and the baking speed is 30m / min, to obtain the corona-resistant enameled copper round wire; the topcoat is oil-resistant polyamide-imide paint, and the thickness of each coating of the topcoat is 0.010mm.

[0086] Furthermore, the oil-resistant polyamide-imide paint is 220 grade polyamide-imide.

[0087] In S500, the surface of the wrapped enameled wire is coated with a topcoat and baked and cured to obtain a corona-resistant enameled copper round wire, which is repeated three times.

[0088] Among them: the paint film thickness of corona resistant enameled copper round wire is 0.075~0.095mm.

[0089] Note: The corona-resistant enameled copper round wire of this application is different from the traditional three-layer structure. The paint film thickness on the corona-resistant enameled copper round wire is not fixed. The position without biting on the primer only needs to be painted twice, while the existing technology has a fixed thickness, so the paint film thickness here is a range value.

[0090] Embodiment 2:

[0091] Example 2 is based on Example 1, and replaces the area marked on the enameled copper round wire on the thermal infrared image as the area of ​​interest with the following method: The method of marking the area marked on the thermal infrared image as the area of ​​interest is: binarizing the thermal infrared image to obtain a binary image, performing Hough line detection on the binary image to obtain straight lines in the binary image; and taking the area between the two longest straight lines as the area of ​​interest.

[0092] Based on Example 1, the heat transfer continuity condition is replaced by the following method:

[0093] TH(AbnA(i-1))≥TH(AbnA(i))≥TH(AbnA(i+1));

[0094] Among them, the TH(AbnA(i)) function is to take the thermal conductivity value of the i-th abnormal enameled area AbnA(i), and the calculation method of the thermal conductivity value TH(AbnA(i)) of AbnA(i) is:

[0095] ;

[0096] Wherein, j is a variable, HG(HighA,AbnA(j)) is the difference between the average temperature value of the high heat transfer area HighA and the average temperature value of each point on the edge of AbnA(j); LG(AbnA(j),LowA) is the difference between the average temperature value of the low heat transfer area LowA and the average temperature value of each point on the edge of AbnA(j); AbnA(j) is the jth abnormal enamel area inside ContinuA along the direction of heat transfer starting from the position of the heat outlet area;

[0097] Among them, HG (HighA, AbnA (j)) and LG (AbnA (j), LowA) can accurately show the difference in temperature values ​​between all abnormal enameled areas along the direction of heat transfer of the jth abnormal enameled area and the jth abnormal enameled area, and can show that intermittent heat transfer inertia is generated in the middle of the heat transfer direction of all abnormal enameled areas.

[0098] If any abnormal enameled area does not meet the heat transfer continuity condition, it is determined that the enameled round copper wire has not bitten the bottom.

[0099] Among them: the paint film thickness of corona resistant enameled copper round wire is 0.075~0.095mm.

[0100] Note: The corona-resistant enameled copper round wire of this application is different from the traditional three-layer structure. The paint film thickness on the corona-resistant enameled copper round wire is not fixed. The position without biting on the primer only needs to be painted twice, while the existing technology has a fixed thickness, so the paint film thickness here is a range value.

[0101] Comparative Example 1: The enameled copper round wire with a specification of 0.63 mm prepared in Example 1 of the Chinese invention patent of announcement number CN111627618B, a production and processing process of enameled wire for oil-cooled driving motor of automobile;

[0102] Comparative Example 2: 220-grade corona-resistant enameled wire with a specification of 0.63 mm produced by Jiangsu Datong Electromechanical Co., Ltd.

[0103] The product characteristics of the enameled copper round wires with a specification of 0.63 mm prepared by Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are compared. The data in the oil and water cold and heat shock resistance test of the Chinese invention patent with announcement number CN111627618B are as follows:

[0104] Among them, the comparison results under the oil-water cold and hot shock test conditions in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are as follows:

[0105] Paint film thickness: The paint film thickness of Example 1 and Example 2 is within the range of 0.075-0.095 mm; the paint film thickness of Comparative Example 1 and Comparative Example 2 is 0.115 mm. (The standard is: ≥ 0.075 mm. If the paint thickness is too small, the insulation performance of the coil will be insufficient; if the paint thickness is too large, the conductivity of the coil will be affected. Therefore, if the paint thickness is greater than the standard, the smaller the better when used in a scroll compressor);

[0106] Appearance (standard is no cracking, floating): Example 1 is qualified, Example 2 is qualified, Comparative Example 1 is qualified, Comparative Example 2 has cracks and floating, and is unqualified;

[0107] Corona resistance (3kv*10khz): 1.3H for Example 1, 1.5H for Example 2; 1.2H for Comparative Example 1, 35 minutes for Comparative Example 2 (Compared with Comparative Example 1, Examples 1 and 2 added anti-corona films, so this index is slightly better);

[0108] Wear resistance (average, unit N): Example 1 is 7.12, Example 2 is 7.87; Comparative Example 1 is 6.94, Comparative Example 2 is 1.67;

[0109] Wear resistance (minimum, unit N): 4.15 for Example 1, 5.19 for Example 2; 6.49 for Comparative Example 1, 1.37 for Comparative Example 2; (Compared with Comparative Example 1, the reason why Example 1 and Example 2 are slightly worse is that the paint film thickness is not fixed, and only two coats of paint are required at positions without primer biting, and the paint film thickness of the primer at some positions is inevitably thinner due to the reduction in the number of coats, so the minimum wear resistance is slightly worse than the data of Comparative Example 1 with a fixed paint film thickness, but there will be no significant wear due to repeated bending in the scroll compressor, so this indicator does not affect the performance of the corona-resistant enameled copper round wire in the case of a dedicated scroll compressor);

[0110] Bending test (standard is no cracking): Example 1 is qualified, Example 2 is qualified, Comparative Example 1 is qualified, and Comparative Example 2 has the paint film falling off after bending;

[0111] Destruction voltage (KV) (3 times): Example 1 is 3.94 / 3.51 / 2.77, Example 2 is 4.38 / 3.79 / 3.52; Comparative Example 1 is 3.76 / 2.50 / 2.61, Comparative Example 2 is 1.26 / 3.45 / 0.82;

[0112] Note: The data of Comparative Examples 1 and 2 are quoted from the Chinese invention patent with announcement number CN111627618B. Figure 1 .

[0113] According to the data results in the oil-water thermal shock resistance experiment, the products of Example 1 and Example 2 prepared by the method provided in the present invention can maintain good performance in the oil-water thermal shock resistance experiment even when the thickness is greatly reduced, especially when the products of Example 1 and Example 2 are used specifically in scroll compressors.

[0114] Among them, the steps of the oil-water thermal shock test (155℃*40H to -45℃*8H in the gearbox oil-immersed sealing environment, a total of 8 cycles) are as follows:

[0115] 1) Initial material performance test;

[0116] 2) 4 / 8 cycle oil-resistant high and low temperature cycle test: At the beginning of the experiment, the temperature was heated from 25℃ to 155℃, and the heating and cooling rate was about 2℃ / min. During the experiment, 155℃ and minus 45℃ were directly switched by temperature impulse, and the switching time was 5min, with high and low temperature cycles.

[0117] Preferably, the present invention further provides an embodiment of a round copper wire, wherein the round copper wire is a corona-resistant enameled round copper wire prepared by the method for preparing a corona-resistant enameled round copper wire specially used for a scroll compressor according to the present invention.

[0118] Although the description of the present invention has been quite detailed and has been described in particular with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, so as to effectively cover the intended scope of the present invention. In addition, the present invention is described above with the embodiments foreseeable by the inventors, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that are not currently foreseen may still represent equivalent changes of the present invention.

Claims

1. Preparation method of corona-resistant enameled copper round wire for scroll compressors. It is characterized in that The method comprises the following steps: S100, annealing the round wire base material to obtain a primer-coated wire; S200, coating a primer on the surface of the primer-coated wire and curing at low temperature to obtain an enameled copper round wire, and after the total number of times of coating the primer and curing at low temperature is greater than or equal to two times, preheating the enameled copper round wire and obtaining a thermal infrared image of the enameled copper round wire; S300, judging whether the enameled copper round wire is bitten according to the thermal infrared image, if yes, the enameled copper round wire is recorded as a wire to be coated with primer and the process goes to step S200; if no, the enameled copper round wire is cured at high temperature to form a paint film and the process goes to step S400; S400, a corona-resistant polyimide film is wrapped around an enameled round copper wire and then baked and sintered to obtain a wrapped enameled wire; S500, coating the surface of the wound enameled wire with topcoat and baking and curing to obtain the corona-resistant enameled copper round wire; In S300, the method for judging whether the enameled copper round wire has bitten the bottom according to the thermal infrared image includes: marking the area of ​​the enameled copper round wire on the thermal infrared image as the area of ​​interest; performing edge detection on the area of ​​interest to obtain multiple edge lines, and dividing each area of ​​interest by the edge lines to obtain multiple enameled areas; marking the enameled area where the average temperature value of each point in the enameled area is less than the average temperature value of each point in the area of ​​interest as an abnormal enameled area; marking the abnormal enameled area with the highest average temperature value as the heat-out area; marking the abnormal enameled area with the lowest average temperature value as the heat-in area; taking the point with the highest temperature value on the edge line of the heat-out area as UpPoint, and taking the point with the lowest temperature value on the edge line of the heat-in area as DoPoint; taking the direction from UpPoint to DoPoint as the heat transfer direction; The abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-outlet area and the abnormal enameled area is called the high heat transfer area HighA; the abnormal enameled area with the smallest absolute value of the difference between the average temperature of the heat-inlet area and the abnormal enameled area is called the low heat transfer area LowA; the straight line passing through the point closest to UpPoint on the edge line of HighA and the point closest to UpPoint on the edge line of LowA is called UpLine; the straight line passing through the point closest to DoPoint on the edge line of HighA and the point closest to DoPoint on the edge of LowA is called DoLine; in the area of ​​interest, the area between UpLine and DoLine is called the heat transfer area ContinuA; Starting from the position of the heat outlet area, each abnormal enameled area inside ContinuA is searched in sequence along the direction of heat transfer. When all abnormal enameled areas meet the heat transfer continuity condition, it is determined that the enameled copper round wire has bitten the bottom; Among them, the heat transfer continuity condition is: HeatC(AbnA(i-1))≥HeatC(AbnA(i)) and HeatC(AbnA(i))≥HeatC(AbnA(i+1)), where AbnA(i) is the i-th abnormal enameled area inside ContinuA along the direction of heat transfer starting from the position of the heat outlet area, and i is the sequence number; the HeatC() function is to take the average temperature value of all points on the edge of the abnormal enameled area; If any abnormal enameled area does not satisfy the heat transfer continuity condition, it is determined that the enameled round copper wire has not bitten the bottom.

2. According to the method for preparing corona-resistant enameled copper round wire for scroll compressors according to claim 1, in S100, the method of annealing the round wire base material to obtain the primer wire to be coated is specifically: annealing the round wire base material in an annealing furnace at a speed of 30 to 60 m / min, and the annealing temperature is 450 to 700°C.

3. The method for preparing corona-resistant enameled round copper wire for scroll compressor according to claim 1, in, The low-temperature curing temperature is 150-200° C., the low-temperature curing speed is 3-300 m / min, and the primer is a high-adhesion polyamide-imide paint.

4. The method for preparing corona-resistant enameled copper round wire for scroll compressor according to claim 1, wherein the heat transfer continuity condition is replaced by: TH(AbnA(i-1))≥TH(AbnA(i))≥TH(AbnA(i+1)); in, The TH(AbnA(i)) function is the thermal conductivity value of the i-th abnormal enameled area AbnA(i).

5. According to the method for preparing corona-resistant enameled copper round wire for scroll compressors described in claim 1, the method for marking the area of ​​the enameled copper round wire on the thermal infrared image as the area of ​​interest is: binarizing the thermal infrared image to obtain a binary image, performing Hough line detection on the binary image to obtain straight lines in the binary image; and taking the area between the two longest straight lines as the area of ​​interest.

6. The method for preparing corona-resistant enameled copper round wire for scroll compressor according to claim 1, wherein the corona-resistant polyimide film is wrapped around the enameled copper round wire and baked and sintered to obtain the wrapped enameled wire, comprising wrapping the corona-resistant polyimide film around the enameled copper round wire in an overlapping manner with an overlap width of 50% or 2 / 3 of the overlap width, and then heating and baking the wrapped enameled wire at a temperature of 200 to 280° C. for 15 to 20 minutes to obtain the wrapped enameled wire.

7. A round copper wire, It is characterized in that The round copper wire is a corona-resistant enameled round copper wire prepared by the method for preparing a corona-resistant enameled round copper wire specially used for a scroll compressor as described in any one of claims 1 to 6.

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