Processing and manufacturing method of high-temperature self-adhesive enameled flat aluminum wire for high-strength CTC

Abstract

The invention belongs to the technical field of enameled flat aluminum wires, and particularly relates to a processing and manufacturing method of a high-temperature self-adhesive enameled flat aluminum wire for high-strength CTC. The bare aluminum flat wire is paid off and straightened; hardening treatment; painting is conducted; traction and take-up are carried out; and performance testing. According to the method, the extruded flat aluminum wire is hardened by adopting an overall section compression process (the compression ratio is 40-50%), so that the problems that the yield strength of an aluminum conductor can only reach 75Mpa and lattice fracture and surface defects are easy to occur in a traditional hardening mode are effectively solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enameled aluminum flat wire, and particularly relates to a processing and manufacturing method of high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC. BACKGROUND

[0002] At present, the winding design of domestic oil-immersed power transformers mainly uses copper materials as the main material, which is mainly due to the excellent electrical conductivity and high mechanical strength of copper materials. The mechanical strength of the winding is directly related to the short-circuit resistance of the transformer, and is one of the key factors to ensure the stable operation of the transformer.

[0003] However, copper materials have significant limitations in application: China is relatively short of copper resources, and the price of copper materials is more than 3 times that of aluminum materials, which leads to high design and manufacturing costs of transformers, which is not conducive to the low-cost development of the industry.

[0004] If aluminum materials are used to replace copper materials, although the cost pressure can be alleviated, aluminum materials have obvious performance deficiencies: the electrical conductivity of aluminum materials is only about 61.5% of that of copper materials, and the mechanical strength is significantly different - the yield strength of normal copper wire is 80-100Mpa, while the yield strength of normal aluminum material is only 30-50Mpa, about 1 / 2 of that of copper material, which is difficult to meet the design requirements of existing transformers.

[0005] Under this background, there is a specific market demand: customers propose that the winding of oil-immersed transformers should use 1.70x4.25mmx25 root CTC high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC, and require that the conductor yield strength of the aluminum flat wire should be more than 90Mpa, and the adhesion strength should meet the requirements of more than 8Mpa at room temperature and more than 5Mpa at 120 DEG C. However, in terms of current technology, the conventional yield strength of aluminum conductor is only 30-50Mpa, and there is no mature standard and process experience for realizing high-temperature self-adhesion of aluminum enameled wire and meeting the above adhesion strength standard. The existing technology cannot meet the design requirements.

[0006] Therefore, it is an urgent problem to be solved in the industry to develop a high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC for oil-immersed power transformers that meets the above performance requirements. SUMMARY

[0007] The purpose of the present application is to provide a processing and manufacturing method of high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC to solve the problems in the prior art.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a processing and manufacturing method of high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC, comprising the following steps: Preparation: the semi-finished product is produced by extrusion process; Bare aluminum flat wire unwinding and straightening; Hardening treatment: the first hardening treatment is performed on the wire by using the whole section compression process, and the section compression rate is controlled to be 40%-50%; the second hardening treatment is performed on the wire by using the whole section compression process, and the section compression rate is controlled to be 40%-50%; and the thickness direction size difference is controlled to be ≤0.01mm; Painting: the insulating paint adopts the structure of acetal paint + high-temperature epoxy self-adhesive paint; the baking temperature of the acetal paint is controlled to be 380℃-400℃, the baking temperature of the high-temperature epoxy self-adhesive paint is controlled to be 360℃-380℃, and the single baking time is controlled to be 0.7-0.8 minutes; Traction and take-up: the painted wire is wound on the take-up reel by traction and take-up to form the finished product; Performance test: the adhesion, flexibility, yield strength, tensile strength, elongation, adhesion strength and resistivity performance of each batch of wire are tested, and the test indexes need to meet: the adhesion is that after the sample is cut and stretched by 15%, the paint film of the raised part is ≤0.4b; the flexibility is that after the enameled aluminum flat wire sample is bent by 180° on the rod diameter of 1a and 1.5b respectively, the paint film should not crack; the yield strength is ≥90Mpa; the tensile strength is ≥90Mpa; the elongation is ≤6.0%; the adhesion strength is ≥8Mpa at room temperature and ≥5Mpa at 120℃; the resistivity at 20℃ is ≤0.02801Ω・mm² / m, and meets the requirements of IEC standard 60317-0-9.

[0009] Preferably, the whole section compression process is to compress the whole size of the wire in the width and thickness directions.

[0010] Preferably, in the hardening treatment, the section compression rates of the first and second whole section compression processes are both in the range of 40%-50%.

[0011] Preferably, in the painting step, the acetal paint and the high-temperature epoxy self-adhesive paint use different baking temperatures, the baking temperature of the acetal paint is 380℃-400℃, and the baking temperature of the high-temperature epoxy self-adhesive paint is 360℃-380℃.

[0012] Preferably, in the painting step, the single baking time is strictly controlled to be 0.7-0.8 minutes.

[0013] Preferably, in the performance test, the adhesion strength needs to meet ≥8Mpa at room temperature and ≥5Mpa at 120℃ at the same time.

[0014] Preferably, in the performance test, the resistivity at 20℃ needs to be ≤0.02801Ω・mm² / m.

[0015] The beneficial effects of the present application are: the present application adopts the overall cross-section compression process (compression rate 40%-50%) to harden the extruded aluminum flat wire, effectively solves the problem that the yield strength of the aluminum conductor can only reach 75Mpa and is prone to lattice fracture and surface defects under the traditional hardening mode, and the yield strength of the aluminum conductor is increased to 90Mpa or more, while the surface quality and resistivity performance of the aluminum material are ensured to meet the design requirements of the oil-immersed power transformer for the high strength of the winding wire.

[0016] In the painting process, the baking temperature of the acetal paint (380-400 DEG C) and the high-temperature epoxy self-adhesive paint (360-380 DEG C) is controlled differently, and the single baking time is limited to 0.7-0.8 minutes, which not only avoids the yield strength decrease caused by the painting process, but also ensures that the adhesive strength reaches the standard of 8Mpa at room temperature and 5Mpa at 120 DEG C. The method realizes the replacement of copper with aluminum, reduces the manufacturing cost of the transformer, improves the short-circuit resistance of the winding, and fills the related process gap. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic diagram of the mold in the present application; Figure 2 is a structural schematic diagram of the product of the present application. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0019] In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0020] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing", "fixed" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] The specific embodiments of the present application will be described in detail below in conjunction with the preferred embodiments and the accompanying drawings.

[0022] A processing and manufacturing method of high-strength high-temperature self-adhesive enameled aluminum flat wire for CTC, the specific implementation steps are as follows: Preparation: The semi-finished product bare aluminum flat wire blank is produced by extrusion process. Aluminum material with required purity is selected, and the aluminum blank is extruded into a preliminarily formed bare aluminum flat wire by an extrusion equipment, so as to ensure that the cross-sectional size of the blank meets the subsequent processing allowance requirement and provides a basis for subsequent hardening treatment.

[0023] Bare aluminum flat wire unwinding and straightening: the extruded bare aluminum flat wire blank is placed on a wire unwinding frame, and the wire is released stably by a wire unwinding device; at the same time, the bare aluminum flat wire is straightened by a straightening machine, and through the synergistic effect of multiple straightening rollers, the defects such as bending and warping of the wire are eliminated, so that the straightness of the wire meets the subsequent processing requirement and ensures the stability of the subsequent hardening treatment and painting process.

[0024] Hardening treatment: the straightened bare aluminum flat wire is subjected to twice hardening treatment by using the whole cross-section compression process.

[0025] First hardening treatment: the whole cross-section of the wire is compressed by using a special drawing die (the die structure is shown in FIG. 1, including a matching drawing die round corner), and the width and thickness of the wire are compressed at the same time during the compression process, and the cross-section compression rate is controlled to be 40%-50% (for example, if the original cross-sectional area is S, the compressed cross-sectional area is 0.5S-0.6S); Second hardening treatment: on the basis of the first compression, the whole cross-section compression process is used again, and the cross-section compression rate is also controlled to be 40%-50%, and the thickness direction size of the wire is monitored by using a precision measuring tool (such as a micrometer), so as to ensure that the thickness direction size difference is ≤0.01mm, so as to ensure the size precision and uniformity of the wire.

[0026] Painting: the bare aluminum flat wire after hardening treatment is subjected to painting treatment, and the insulating paint adopts a composite structure of "acetal paint + high-temperature epoxy self-adhesive paint".

[0027] First, the surface of the conductor is evenly coated with acetal paint, then the conductor coated with acetal paint is introduced into a baking furnace, the baking temperature is controlled at 380-400℃, the single baking time is 0.7-0.8 minutes (the baking time is ensured by adjusting the conductor pulling speed, for example, the pulling speed is 1.2-1.4 m / min), so that the acetal paint is cured to form a bottom insulating film; After the bottom insulating film is cured, high-temperature epoxy self-adhesive paint is continuously and evenly coated on the surface thereof, then the conductor is introduced into another baking furnace, the baking temperature is controlled at 360-380℃, and the single baking time is also 0.7-0.8 minutes, so that the high-temperature epoxy self-adhesive paint is cured to form a self-adhesive layer, and the paint coating process is completed.

[0028] Traction and take-up: the coated conductor is subjected to stable tension by a traction machine, and is pulled to a take-up device, and is taken up by a take-up reel according to the set winding tension and arrangement mode, and finally forms a finished product of the uniformly wound enameled aluminum flat conductor.

[0029] Performance test: each batch of finished product conductor needs to be subjected to comprehensive performance test, and the test method and index are as follows: Adhesion: after the sample is cut and stretched by 15%, the paint film lifting part is observed, and the lifting part is required to be ≤0.4b (b is the size of the narrow surface of the flat conductor); Flexibility: the wide surface of the enameled aluminum flat conductor sample is bent by 180° on a rod with a diameter of 1a (a is the size of the wide surface of the flat conductor), and the narrow surface is bent by 180° on a rod with a diameter of 1.5b, and the paint film is required to have no cracking; Yield strength and tensile strength: tested by a tensile testing machine, the yield strength is required to be ≥90Mpa, and the tensile strength is required to be ≥90Mpa; Elongation: tested by a tensile testing machine, the elongation is required to be ≤6.0%; Adhesion strength: tested at room temperature and at 120℃ environment respectively, the adhesion strength is required to be ≥8Mpa at room temperature and ≥5Mpa at 120℃; Resistivity: tested by a resistivity meter at 20℃ environment, the resistivity is required to be ≤0.02801Ω・mm² / m.

[0030] All test results need to meet the requirements of IEC standard 60317-0-9 at the same time, so as to be determined as qualified products.

[0031] At present, the yield strength of the aluminum conductor produced by extrusion is 30-50 MPa, and after the traditional hardening treatment, the yield strength can reach 70 MPa; if further hardening treatment is carried out, the yield strength reaches 75 MPa, and at the same time, the lattice of the aluminum material surface will be broken to cause defects; it cannot meet the design requirements of the customer. The whole section compression process is adopted to compress the extruded aluminum flat wire, and the compression rate is controlled at 40%-50%; the yield strength and resistivity performance of the bare aluminum flat wire produced by the whole section compression process can meet the design requirements of the customer. When the bare aluminum flat wire is painted, the insulating paint needs to be baked and solidified into an insulating paint film through a certain temperature and time; if the existing coating process is adopted, on the one hand, the yield strength will decrease by about 20%; on the other hand, the baking temperature and time of different insulating paints are different, and the adhesion strength performance cannot meet the requirements; it cannot meet the requirements of the customer. The different baking temperatures of different insulating paint materials are controlled, the baking temperature of the acetal paint is controlled at 380-400 DEG C, the baking temperature of the high-temperature epoxy self-adhesive paint is controlled at 360-380 DEG C, and the single baking time is controlled at 0.7-0.8 minutes; the yield strength requirements are met, and the adhesion strength requirements of the aluminum flat wire are met. Thus, the customer's requirements for the high-strength CTC high-temperature self-adhesive enameled aluminum flat wire for oil-immersed power transformer are met, the yield strength and adhesion strength of the aluminum conductor meet the requirements of normal copper conductor; the short-circuit resistance of the transformer winding is improved, and the design and manufacturing cost of the oil-immersed transformer is reduced. There is no publication of using the whole section compression process to control the compression rate at 40%-50% and using different baking temperatures for different insulating paints.

[0032] The whole section compression process adopted by the application, the compression rate is controlled at 40%-50%, and different baking temperatures are adopted for different insulating paints, which is developed after repeated research and is creative.

[0033] The yield strength of the aluminum conductor produced by extrusion is 30-50 MPa, and after the traditional hardening treatment, the yield strength can reach 70 MPa; if further hardening treatment is carried out, the yield strength reaches 75 MPa, and at the same time, the lattice of the aluminum material surface will be broken to cause defects; it cannot meet the design requirements of the customer. The whole section compression process is adopted to compress the extruded aluminum flat wire, and the compression rate is controlled at 40%-50%; the yield strength and resistivity performance of the bare aluminum flat wire produced by the whole section compression process can meet the design requirements of the customer.

[0034] In summary, the main distinguishing technical features of the present application are that the aluminum conductor yield strength is ≥ 90Mpa, the enameled aluminum flat wire adhesion strength at room temperature is ≥ 8Mpa, and the adhesion strength at 120℃ is ≥ 5Mpa. The production method, i.e. process and parameters, of the high-temperature self-adhesive enameled aluminum flat wire for high-strength CTC has not been implemented by the same process, and there is no related publication. It provides a new production method for the high-temperature self-adhesive enameled aluminum flat wire for high-strength CTC with yield strength ≥ 90Mpa, adhesion strength at room temperature ≥ 8Mpa, and adhesion strength at 120℃ ≥ 5Mpa, and produces a new type of enameled aluminum flat wire product. The production of the high-temperature self-adhesive enameled aluminum flat wire for high-strength CTC fills the production process blank of enameled aluminum flat wire with yield strength ≥ 90Mpa, adhesion strength at room temperature ≥ 8Mpa, and adhesion strength at 120℃ ≥ 5Mpa.

[0035] In summary, the method is reasonable in design, simple in operation, stable and reliable in performance, can effectively improve the quality and yield of production, and has very significant application effect.

[0036] It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for processing and manufacturing high-strength, high-temperature self-adhesive enameled aluminum rectangular wire for CTC, characterized in that: The following steps are involved: Material preparation: semi-finished products are produced using extrusion technology; Paying off and straightening of bare aluminum flat wire; Hardening treatment: First, the conductor is hardened using the overall cross-section compression process, with the cross-section compression rate controlled at 40% to 50%. Then, the conductor is hardened using the overall cross-section compression process for the second time, with the cross-section compression rate controlled at 40% to 50%. The thickness dimension difference is controlled to be ≤0.01mm. Painting: The insulating paint adopts acetal paint + high-temperature epoxy self-adhesive paint structure; the baking temperature of acetal paint is controlled at 380℃-400℃, and the baking temperature of high-temperature epoxy self-adhesive paint is controlled at 360℃-380℃, and the single baking time is controlled at 0.7-0.8 minutes; Pulling and winding: The painted wire is pulled and wound onto a winding reel to form a finished product; Performance testing: Each batch of wires is tested for adhesion, flexibility, yield strength, tensile strength, elongation, bonding strength, and resistivity. Test indicators must meet the following requirements: Adhesion: After the specimen is cut and stretched 15%, the lift of the paint film should be ≤0.4b; Flexibility: After the wide and narrow sides of the enameled aluminum flat wire specimen are bent 180° on rods with diameters of 1a and 1.5b, respectively, the paint film should not crack; Yield strength ≥90Mpa; Tensile strength ≥90Mpa; Elongation ≤6.0%; Bond strength ≥8Mpa at room temperature and ≥5Mpa at 120°C; Resistivity ≤0.02801Ω・mm² / m at 20°C, and compliance with the requirements of IEC standard 60317-0-9.

2. The processing and manufacturing method according to claim 1, characterized in that: The overall cross-section compression process is to compress the overall dimensions of the wire in the width and thickness directions.

3. The processing and manufacturing method according to claim 1, characterized in that: In the hardening treatment, the cross-sectional compression rates of the first and second overall cross-sectional compression processes are both within the range of 40% to 50%.

4. The processing and manufacturing method according to claim 1, characterized in that: In the painting step, the acetal paint and the high-temperature epoxy self-adhesive paint adopt different baking temperatures, the baking temperature of the acetal paint is 380°C-400°C, and the baking temperature of the high-temperature epoxy self-adhesive paint is 360°C-380°C.

5. The processing and manufacturing method according to claim 1, characterized in that: In the painting step, the single baking time is strictly controlled within 0.7-0.8 minutes.

6. The processing and manufacturing method according to claim 1, characterized in that: In the performance test, the bonding strength must meet the requirements of ≥8 MPa at room temperature and ≥5 MPa at 120°C.

7. The processing and manufacturing method according to claim 1, characterized in that: In the performance test, the resistivity at 20°C must be ≤0.02801Ω・mm² / m.

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