A square enameled wire and its preparation method

Abstract

The present invention discloses a square enameled wire and a preparation method thereof, which are mainly used for motors of new energy electric vehicles; the square enameled wire includes an electromagnetic wire conductor, a first insulating layer, a nylon layer, a second insulating layer and a third insulating layer, the cross-section of the electromagnetic wire conductor is a square with rounded corners, the first insulating layer is a polyesterimide coating, the second insulating layer is a corona-resistant polyamideimide coating, and the third insulating layer is a polyamideimide coating. The square enameled wire disclosed by the present invention adopts a square conductor with rounded corners and is produced by a process of a composite coating with a certain proportional relationship, so that different enamel layers complement each other. The produced product has low dielectric loss, excellent thermal shock performance, high softening breakdown temperature, excellent wear resistance, scratch resistance, etc. The coil made of the wire has a very high power density characteristic.

Description

Technical Field

[0001] The invention relates to an enameled wire and a preparation method thereof, in particular to a square enameled wire and a preparation method thereof. Background Art

[0002] As people's awareness of environmental protection increases, electric vehicles have entered daily life, the demand for them is growing, and the requirements for variety and performance are getting higher and higher, which puts higher requirements on the supporting raw materials, components, etc. This has brought both opportunities and challenges to the development of basic industries such as raw materials and components.

[0003] At present, most of the enameled wires used in electric vehicle drive motors have the following problems: due to the simple process, single paint film, and the conductor structure is generally round wire or flat wire, the products produced have poor corona resistance, poor thermal shock resistance, and the power density of the motor is not strong.

[0004] CN101958158B discloses a method for preparing a corona-resistant enameled wire and a product thereof, wherein the corona-resistant enameled wire is formed of three insulating layers of polyester corona-resistant paint, polyester imide corona-resistant paint and polyamide-imide paint, and the enameled wire can have a maximum corona-resistant life of 55 hours. However, since it uses two layers of corona-resistant paint, the cost is relatively high and it is not suitable for large-scale production by enterprises.

[0005] CN104804503B also discloses an anti-corona enameled wire that can be used in new energy vehicles and a method for manufacturing the same. The enameled wire uses polyesterimide as an inner layer coating, a corona-resistant coating as an intermediate layer, and a polyamideimide-based coating as an outer layer. The enameled wire can have a corona resistance life of up to 50 hours. However, during the production process, the process involves 20 steps, the production steps are complicated, and the cost is high.

[0006] CN207199331U discloses a 200-grade corona-resistant enameled wire for new energy vehicle drive motors, which uses a tin layer, polyester imide paint, nylon paint, polyester amide imide paint and polyamide imide paint to form a composite insulating layer enameled wire. Although this enameled wire can initially meet the needs of the motor, its production process uses 22-28 steps, and the process is complicated and cumbersome. Summary of the invention

[0007] The object of the present invention is to provide a square enameled wire with high heat resistance and corona resistance and a preparation method thereof. The square enameled wire obtained by the present invention has strong thermal shock resistance and can meet the high-frequency pulse voltage time requirements of new energy drive motors, while simplifying the production process and reducing production costs.

[0008] The technical solution adopted by the present invention to solve the above technical problems is to provide a square enameled wire, including an electromagnetic wire conductor, the cross-section of the electromagnetic wire conductor is square, and the electromagnetic wire conductor is sequentially wrapped with a first insulating layer, a nylon layer, a second insulating layer, and a third insulating layer; the first insulating layer is a polyesterimide coating, the second insulating layer is a corona-resistant polyamideimide coating, and the third insulating layer is a polyamideimide coating; the thickness of the first insulating layer is 0.015 - 0.04 mm, the thickness of the nylon layer is 0.003 - 0.008 mm, the thickness of the second insulating layer is 0.03 - 0.08 mm, and the thickness of the third insulating layer is 0.01 - 0.03 mm.

[0009] Further, the thickness ratio of the first insulating layer, the nylon layer, the second insulating layer, and the third insulating layer is 5:1:10:4.

[0010] Further, arc corners are formed around the electromagnetic wire conductor.

[0011] Further, the side length of the electromagnetic wire conductor is 1.5 - 4 mm, and the radius of the rounded corner is 0.18 - 0.5 mm.

[0012] The present invention also provides a method for preparing a square enameled wire, including the following steps:

[0013] S1: Extruding the electromagnetic wire conductor on an extrusion device to form a square wire;

[0014] S2: Annealing the square wire at a speed of 4 - 20 meters per minute through an annealing furnace;

[0015] S3: Placing the square wire in a cooling water tank for cooling, cleaning, and air drying;

[0016] S4: Coating polyesterimide paint on the surface of the square wire and baking and curing it as the first insulating layer, then coating nylon paint on the surface of the first insulating layer and baking and curing it as the nylon layer, then coating corona-resistant polyamideimide paint on the nylon layer and baking and curing it as the second insulating layer, and finally coating polyamideimide paint on the second insulating layer and baking and curing it as the third insulating layer to obtain a square enameled wire;

[0017] Further, the step S4 includes:

[0018] When the temperature of the square wire is 35 - 40 °C, coating polyesterimide paint in 2 - 3 passes to form the first insulating layer, coating according to a paint film thickness mold with an increase of 0.005 - 0.013 in the wire diameter, and baking and curing in multiple passes to control the total thickness of this layer to be 0.015 - 0.04 mm;

[0019] When the temperature of the square wire is 35 - 40 °C, apply a layer of nylon paint on the surface of the first insulating layer to form a nylon layer, and then bake and cure it, controlling the thickness of this layer to be 0.003 - 0.008 mm;

[0020] When the temperature of the square wire is 40 - 45 °C, apply corona-resistant polyamide-imide paint on the surface of the nylon layer in 4 - 6 coats to form a second insulating layer. Coat according to the paint film thickness mold with an increase of 0.048 - 0.128 mm in wire aperture, and bake and cure in separate coats, controlling the total thickness of this layer to be 0.03 - 0.08 mm;

[0021] When the temperature of the square wire is 45 - 50 °C, apply polyamide-imide paint on the surface of the second insulating layer in 2 - 3 coats to form a third insulating layer. Coat according to the paint film thickness mold with an increase of 0.058 - 0.158 mm in wire aperture, and bake and cure in separate coats, controlling the total thickness of this layer to be 0.01 - 0.03 mm to obtain a square enameled wire.

[0022] The baking process is that the square wire passes through the evaporation zone and the curing zone of the baking furnace at a speed of 5 - 20 meters per minute.

[0023] Furthermore, the annealing furnace is divided into an inlet zone and an outlet zone. The temperature of the inlet zone is 580 - 600 °C, and the temperature of the outlet zone is 540 - 560 °C.

[0024] Furthermore, the baking furnace is divided into an evaporation zone and a curing zone. The temperature of the evaporation zone is 200 - 230 °C, and the temperature of the curing zone is 350 - 500 °C.

[0025] Furthermore, the baking furnace includes a main circulation fan, an exhaust fan, and a lower furnace mouth fan. The rotational speed of the main circulation fan is 1000 - 1600 revolutions per minute, the rotational speed of the exhaust fan is 500 - 1200 revolutions per minute, and the rotational speed of the lower furnace mouth fan is 800 - 1600 revolutions per minute.

[0026] The present invention has the following beneficial effects compared with the prior art: The square enameled wire provided by the present invention uses a square electromagnetic wire conductor with rounded corners and is produced by a process of a composite coating with a certain proportional relationship, enabling different paint layers to interact and coordinate with each other. And there are only 13 coats of the applied paint layer. The produced product has a low dielectric loss, while maintaining excellent thermal shock performance and a high softening breakdown temperature, and can further enhance wear resistance and scratch resistance, etc., enabling the coil made of the wire to further improve the power density characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the square enameled wire of the present invention.

[0028] In the figure:

[0029] 1 - Electromagnetic wire conductor; 2 - First insulating layer; 3 - Nylon layer; 4 - Second insulating layer; 5 - Third insulating layer Detailed implementation mode

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Please refer to Figure 1 The square enameled wire provided by the present invention includes an electromagnetic wire conductor 1, a first insulating layer 2, a nylon layer 3, a second insulating layer 4, and a third insulating layer 5. The material of the electromagnetic wire conductor 1 is copper, and its cross-section is a square with rounded corners, the side length is 1.5 - 4 mm, and the radius of the rounded corners is 0.18 - 0.5 mm. The first insulating layer 2 is a polyesterimide coating with a thickness of 0.015 - 0.035 mm, the thickness of the nylon layer 3 is 0.003 - 0.008 mm, the second insulating layer 4 is a corona-resistant polyamideimide coating with a thickness of 0.03 - 0.07 mm, and the third insulating layer 5 is a polyamideimide coating with a thickness of 0.01 - 0.03 mm. The polyesterimide coating has good adhesion to the copper wire, but its hydrolysis resistance, oil resistance, and chemical resistance are poor. The corona-resistant polyamideimide coating has good corona resistance under high-voltage and high-frequency conditions, but its adhesion is poor, the cost is high, and the leveling property and surface quality are poor. The polyamideimide coating has good heat resistance, hydrolysis resistance, and chemical resistance and is suitable as an outer coating. A nylon layer is coated between the first insulating layer and the second insulating layer to increase the mechanical strength of the enameled wire.

[0032] In the following embodiments, the first insulating layer uses the MT533 type 180-grade polyesterimide coating produced by Allnex Electrical Insulation Materials (Tongling) Co., Ltd., the second insulating layer uses the 38SAS type 200-grade corona-resistant polyamideimide coating produced by Formosa Chemical & Fibre Co., Ltd. in Taiwan, and the third insulating layer uses the PAI602 type 220-grade polyamideimide coating produced by Allnex Electrical Insulation Materials (Tongling) Co., Ltd.

[0033] Embodiment 1

[0034] The low-oxygen copper rod is extruded on an extrusion device into a square bare wire 1 with a side length of 1.6 mm, and the square bare wire 1 has 4 rounded corners with a radius of 0.2 mm. The square bare wire 1 is sequentially passed through the annealing tube inlet area and the annealing tube outlet area of the annealing furnace at a speed of 12 m / min for finished annealing. The temperature in the annealing tube inlet area is controlled at 580 °C, and the temperature in the annealing tube outlet area is controlled at 540 °C. Then, the square bare wire 1 is passed into a cooling water tank for cooling and cleaning. The cooling water tank contains deionized water at 80 - 90 °C, and then it is dried with a blower and the temperature of the square bare wire 1 is controlled at 35 - 50 °C.

[0035] Apply 2 - 3 coats of polyesterimide paint on the surface of the square bare wire 1 as the first insulating layer 2, with the paint film thickness being: 0.020 mm; then apply 1 coat of high mechanical strength nylon layer 3 on the surface of the first insulating layer 2, with the paint film thickness being: 0.004 mm; then apply 6 coats of corona - resistant polyamideimide paint on the surface of the high mechanical strength nylon layer 3 as the second insulating layer 4, with the paint film thickness being: 0.040 mm; then apply 2 coats of polyamideimide paint on the surface of the second insulating layer 4 as the third insulating layer 5 for improving thermal performance, high mechanical strength and chemical resistance, with the paint film thickness being: 0.016 mm; thus obtaining a square enameled wire.

[0036] Pass the square enameled wire through the evaporation zone and curing zone of the baking oven at a speed of 12 meters per minute for baking. The temperature of the oven inlet zone is 220 °C, the temperature of the evaporation zone of the baking oven is controlled at 300 °C, the temperature of the middle zone of the baking oven is 380 °C, the temperature of the curing zone of the baking oven is controlled at 400 °C, the temperature before the first - stage catalysis of the baking oven is controlled at 480 °C, the rotational speed of the main circulation fan of the baking oven is controlled at 1300 r / min, the rotational speed of the waste - discharging fan of the baking oven is controlled at 800 r / min, and the rotational speed of the lower furnace - mouth fan of the baking oven is controlled at 1100 r / min.

[0037] Apply wiring oil on the surface of the square enameled wire and arrange it precisely on the take - up reel.

[0038] Conduct a high - frequency pulse voltage resistance test on the obtained square enameled wire. The normal high - frequency pulse voltage resistance time reaches more than 60 hours, and the high - frequency pulse voltage resistance time after stretching reaches more than 40 hours.

[0039] Example 2

[0040] The square bare wire 1 used in Example 2 is the same as that in Example 1, and the temperature and wind speed of the baking oven are also the same. The difference lies in that 3 coats of polyesterimide paint are applied on the surface of the square bare wire 1 as the first insulating layer, with the paint film thickness being 0.024 mm; then 6 coats of corona - resistant polyamideimide paint are applied on the surface of the first insulating layer as the corona - resistant layer, with the paint film thickness being 0.040 mm; then 2 coats of polyamideimide paint are applied on the surface of the corona - resistant polyamideimide paint as the insulating layer for improving thermal performance, high mechanical strength and chemical resistance, with the paint film thickness being 0.016 mm.

[0041] Conduct a high - frequency pulse voltage resistance test on the obtained square enameled wire. The normal high - frequency pulse voltage resistance time reaches more than 58 hours, and the high - frequency pulse voltage resistance time after stretching reaches more than 35 hours.

[0042] Example 3

[0043] Example 3 uses the same square bare wire 1 as Example 1, and the temperature and wind speed of the baking oven are also the same. The difference is that 2 coats of polyesterimide paint are applied on the surface of the square bare wire 1 as the first insulating layer, and the film thickness is 0.020 mm; then 1 coat of high mechanical strength nylon layer is applied on the surface of the first insulating layer, and the film thickness is 0.004 mm. Then, 8 coats of polyamideimide paint are applied on the surface of the high mechanical strength nylon layer, and the film thickness is 0.056 mm.

[0044] The obtained square enameled wire is tested for its resistance to high-frequency pulse voltage. The normal high-frequency pulse voltage resistance time reaches more than 33 hours, and the high-frequency pulse voltage resistance time after stretching reaches more than 20 hours.

[0045] Example 4

[0046] The difference between Example 4 and Example 3 is that the polyamideimide paint is replaced with corona-resistant polyamideimide paint, and the film thickness is the same.

[0047] The obtained square enameled wire is tested for its resistance to high-frequency pulse voltage. The normal high-frequency pulse voltage resistance time reaches more than 60 hours, and the high-frequency pulse voltage resistance time after stretching reaches more than 40 hours.

[0048]

[0049]

[0050] Example 5

[0051] The low-oxygen copper rod is extruded into a square bare wire 1 with a side length of 2.25 mm on an extrusion device, and the square bare wire 1 has 4 rounded corners with a radius of 0.28 mm. The square bare wire 1 is sequentially passed through the annealing tube inlet area and the annealing tube outlet area of the annealing furnace at a speed of 8 m / min for finished annealing. The annealing tube inlet area is controlled at a temperature of 580 °C, and the annealing tube outlet area temperature is controlled at 550 °C. Then, the square bare wire 1 is passed into a cooling water tank for cooling and cleaning. The cooling water tank contains deionized water at 80 - 90 °C, and then it is dried with a blower and the temperature of the square bare wire 1 is controlled at 35 - 50 °C.

[0052] On the surface of the square bare wire 1, 2 to 3 coats of polyesterimide paint are applied as the first insulating layer 2, and the film thickness is: 0.022 - 0.03 mm; then, 1 coat of the above high mechanical strength nylon layer 3 is applied on the surface of the first insulating layer 2, and the film thickness is: 0.004 - 0.006 mm; then, 4 to 6 coats of corona-resistant polyamideimide paint are applied on the surface of the high mechanical strength nylon layer 3 as the second insulating layer 4, and the film thickness is: 0.045 - 0.055 mm; then, 2 to 3 coats of polyamideimide paint are applied on the second insulating layer 4 as the third insulating layer 5 to improve thermal performance, high mechanical strength, and chemical resistance, and the film thickness is: 0.018 - 0.022 mm; thus, a square enameled wire is obtained.

[0053] The square enameled wire is passed through the evaporation zone and the curing zone of the baking oven in sequence at a speed of 8 meters per minute for baking. The temperature of the evaporation zone of the baking oven is controlled at 200 °C, the temperature of the curing zone of the baking oven is controlled at 420 °C, the temperature before the first catalysis of the baking oven is controlled at 480 °C, the rotational speed of the main circulation fan of the baking oven is controlled at 1500 r / min, the rotational speed of the waste exhaust fan of the baking oven is controlled at 800 r / min, and the rotational speed of the lower furnace mouth fan of the baking oven is controlled at 1100 r / min.

[0054] The surface of the square enameled wire is coated with row wire oil and precisely arranged on the take-up reel.

[0055] The obtained square enameled wire is subjected to a high-frequency pulse voltage resistance test for 40 hours.

[0056] Example Six

[0057] The low-oxygen copper rod is extruded into a square bare wire 1 with a side length of 3.35 mm on an extrusion device, and the square bare wire 1 has 4 rounded corners with a radius of 0.42 mm. The square bare wire 1 is passed through the annealing tube inlet area and the annealing tube outlet area of the annealing furnace in sequence at a speed of 5 meters per minute for finished product annealing. The annealing tube inlet area is controlled at a temperature of 600 °C, and the annealing tube outlet area temperature is controlled at 550 °C. Then, the square bare wire 1 is passed into a cooling water tank for cooling and cleaning. The cooling water tank contains deionized water at 80 - 90 °C, and then it is dried with a blower and the temperature of the square bare wire 1 is controlled at 35 - 50 °C.

[0058] Apply 2 - 3 coats of polyesterimide paint on the surface of the square bare wire 1 as the first insulating layer 2, and control the total thickness of the paint film of this layer to be 0.03 mm; then apply one layer of high mechanical strength nylon layer 3 on the surface of the first insulating layer, with the paint film thickness of 0.006 mm; then apply 4 - 6 coats of corona - resistant polyamideimide paint on the surface of the high mechanical strength nylon layer 3 as the second insulating layer 4, and control the total thickness of the paint film of this layer to be 0.06 mm; then apply 2 - 3 coats of polyamideimide paint on the second insulating layer 4 as the third insulating layer 5 to improve thermal performance, high mechanical strength and chemical resistance, and control the paint film thickness of this layer to be 0.024 mm; thus obtaining a square enameled wire.

[0059] Pass the square enameled wire through the evaporation zone and the curing zone of the baking oven at a speed of 5 meters per minute for baking. The temperature of the evaporation zone of the baking oven is controlled at 200 °C, the temperature of the curing zone of the baking oven is controlled at 480 °C, the temperature before the first catalysis of the baking oven is controlled at 480 °C, the rotational speed of the main circulation fan of the baking oven is controlled at 1500 r / min, the rotational speed of the waste - discharging fan of the baking oven is controlled at 800 r / min, and the rotational speed of the lower furnace - mouth fan of the baking oven is controlled at 1100 r / min.

[0060] Coat the surface of the square enameled wire with arranging oil and precisely arrange it on the take - up reel.

[0061] Conduct a high - frequency pulse voltage resistance test on the obtained square enameled wire for 45 hours.

[0062] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the claims.

Claims

1. A preparation method of a square enameled wire, characterized in that The square enameled wire includes an electromagnetic wire conductor with a square cross-section. The electromagnetic wire conductor is successively wrapped with a first insulating layer, a nylon layer, a second insulating layer, and a third insulating layer; the first insulating layer is a polyesterimide coating, the second insulating layer is a corona-resistant polyamideimide coating, and the third insulating layer is a polyamideimide coating; the thickness of the first insulating layer is 0.015 - 0.04 mm, the thickness of the nylon layer is 0.003 - 0.008 mm, the thickness of the second insulating layer is 0.03 - 0.08 mm, and the thickness of the third insulating layer is 0.01 - 0.03 mm; The preparation method includes the following steps: S1: Extrude the electromagnetic wire conductor on an extrusion device to form a square wire; S2: Anneal the square wire at a speed of 4 - 20 meters per minute through an annealing furnace; S3: Place the square wire in a cooling water tank for cooling, cleaning, and air drying; S4: Coat the surface of the square wire with polyesterimide paint and bake and cure it to form the first insulating layer. Then coat the surface of the first insulating layer with nylon paint and bake and cure it to form the nylon layer. Then coat the nylon layer with corona-resistant polyamideimide paint and bake and cure it to form the second insulating layer. Finally, coat the second insulating layer with polyamideimide paint and bake and cure it to form the third insulating layer to obtain the square enameled wire; When the temperature of the square wire is 35 - 40 °C, coat the polyesterimide paint in 2 - 3 passes to form the first insulating layer. Coat it according to a paint film thickness mold with an increase in wire diameter of 0.005 - 0.013, and bake and cure it in passes, controlling the total thickness of this layer to be 0.015 - 0.04 mm; When the temperature of the square wire is 35 - 40 °C, coat 1 pass of nylon paint on the surface of the first insulating layer to form the nylon layer, and bake and cure it, controlling the thickness of this layer to be 0.003 - 0.008 mm; When the temperature of the square wire is 40 - 45 °C, coat the corona-resistant polyamideimide paint on the surface of the nylon layer in 4 - 6 passes to form the second insulating layer. Coat it according to a paint film thickness mold with an increase in wire diameter of 0.048 - 0.128 mm, and bake and cure it in passes, controlling the total thickness of this layer to be 0.03 - 0.08 mm; When the temperature of the square wire is 45 - 50 °C, coat the polyamideimide paint on the surface of the second insulating layer in 2 - 3 passes to form the third insulating layer. Coat it according to a paint film thickness mold with an increase in wire diameter of 0.058 - 0.158 mm, and bake and cure it in passes, controlling the total thickness of this layer to be 0.01 - 0.03 mm to obtain the square enameled wire; The baking is that the square wire passes through the evaporation zone and the curing zone of the baking furnace at a speed of 5 - 20 meters per minute.

2. The preparation method of the square enameled wire according to claim 1, characterized in that, The thickness ratio of the first insulating layer, the nylon layer, the second insulating layer, and the third insulating layer is 5:1:10:

4.

3. The preparation method of the square enameled wire according to claim 1, characterized in that, Arc corners are formed around the electromagnetic wire conductor.

4. The preparation method of the square enameled wire according to claim 3, characterized in that, The side length of the electromagnetic wire conductor is 1.5 - 4 mm, and the radius of the arc corner is 0.18 - 0.5 mm.

5. The preparation method of the square enameled wire according to claim 1, characterized in that The annealing furnace is divided into an inlet area and an outlet area. The temperature of the inlet area is 580 - 600 °C, and the temperature of the outlet area is 540 - 560 °C.

6. The preparation method of the square enameled wire according to claim 1, characterized in that, The drying oven is divided into an evaporation area and a curing area. The temperature of the evaporation area is 200 - 230 °C, and the temperature of the curing area is 350 - 500 °C.

7. The method for preparing the square enameled wire according to claim 6, wherein The drying oven includes a main circulation fan, an exhaust fan, and a lower furnace mouth fan. The rotation speed of the main circulation fan is 1000 - 1600 revolutions per minute, the rotation speed of the exhaust fan is 500 - 1200 revolutions per minute, and the rotation speed of the lower furnace mouth fan is 800 - 1600 revolutions per minute.

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