Filling resin curing process for water-cooled transmission bus, high-voltage large-current transmission bus and preparation method of high-voltage large-current transmission bus

Abstract

The invention belongs to the technical field of resin curing processes and power transmission equipment, and particularly relates to a curing process of filling resin for a water-cooled transmission bus, a high-voltage large-current transmission bus and a preparation method of the high-voltage large-current transmission bus. According to the preparation method disclosed by the invention, firstly, mixed resin with a specific proportion is utilized, and a multi-stage heating curing treatment and a multi-stage cooling process are carried out based on autoclave molding, so that the cured resin and epoxy glass cloth composite material with good dielectric properties and mechanical properties is prepared. And secondly, in the process of preparing the high-voltage and high-current transmission bus, the filling resin for the water-cooled transmission bus is used for filling and coating the epoxy glass cloth prepreg, and the integrated high-voltage and high-current transmission bus which is accurate in bending, high-performance in filling resin and high-strength in insulation coating is prepared by perfecting technical details.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resin curing process and power transmission equipment, and particularly relates to a filling resin curing process for a water-cooled transmission bus, a high-voltage and large-current transmission bus and a preparation method thereof. BACKGROUND

[0002] The insulated bus is one of important components in a power transmission and distribution system, and is widely used in large enterprises such as power generation, power transmission and transformation. With the rapid increase of power load, the system operating current is getting larger and larger, the load is getting more and more concentrated, and the main transformer capacity of the transformer substation is also getting larger and larger. In the past engineering, the connection mode of multiple rectangular busbars or the direct use of cables is adopted, which cannot well adapt to the working mode of large current (above 3000A), and the heating phenomenon is obvious. The high-voltage and large-current insulated bus in foreign countries is generally made by resin integral casting, and the high-voltage insulated bus with special bending shape is generally made by vacuum casting method. The insulation layer of the bus is a composite of epoxy resin and inorganic material.

[0003] In the field of extra-high voltage AC and DC power transmission, the transmission bus as the core component of energy transmission needs to withstand rated current of thousands of amperes and insulation voltage of tens of kilovolts. The high-voltage and large-current transmission bus will generate a lot of heat, and a water channel must be designed for cooling. At the same time, the insulation layer must be able to withstand high temperature, and the insulation layer must be dense without air gap and low partial discharge.

[0004] In the current prior art, the filling resin used in the high-voltage transmission bus is mostly general epoxy, which has poor matching of dielectric properties and mechanical properties, and is prone to curing shrinkage and interface debonding, resulting in positive and negative gap discharge. In addition, during use, there are also technical problems such as insulation layer aging breakdown and uneven resin filling.

[0005] Therefore, it is necessary to start from a new angle to prepare a filling resin which has good dielectric properties and mechanical properties after curing.

[0006] Secondly, we also notice that the high-voltage transmission bus in the prior art also has many deficiencies in the details of the preparation process:

[0007] Firstly, the conductor bending is mostly directly bent, and the cooling water channel is prone to deformation, collapse and blockage. The cross-sectional deformation rate is usually more than 3%, which affects the heat dissipation efficiency.

[0008] Secondly, the insulation coating mostly uses a single material or a simple composite structure, or even uses a conventional hand lay-up process. The internal porosity of the cured product is large, the partial discharge is large, the high-voltage and heat aging resistance is insufficient, and the insulation fails easily during long-term operation.

[0009] Thirdly, the transmission bus is made of single pole, two buses are needed for DC transmission, and four buses are needed for AC transmission, which brings great workload to installation.

[0010] Therefore, developing an integrated high-voltage and large-current transmission bus considering precise bending, high-performance filling resin and high-strength insulation covering and a preparation method thereof has become a key technical breakthrough point in the field. SUMMARY

[0011] The present application provides a filling resin curing process for water-cooled transmission bus, a high-voltage and large-current transmission bus and a preparation method thereof, which is based on the above-mentioned problems in the prior art. The resin curing product and epoxy glass cloth composite material with good dielectric and mechanical properties are prepared by using a specific proportion of mixed resin, multi-stage temperature curing treatment and multi-stage cooling process based on hot press tank molding. In the process of preparing the high-voltage and large-current transmission bus, the filling resin for water-cooled transmission bus is used for filling and epoxy glass cloth prepreg coating, and through perfecting the technical details, the integrated high-voltage and large-current transmission bus considering precise bending, high-performance filling resin and high-strength insulation covering is prepared.

[0012] To achieve the above-mentioned purpose, the present application is realized by the following technical measures.

[0013] In one aspect, the present application provides a filling resin curing process for water-cooled transmission bus, comprising the following steps:

[0014] (1) The raw materials including the following components are mixed by mass fraction to obtain a mixture:

[0015] Hain epoxy resin 38-42 parts,

[0016] Benzoxazine resin 28-32 parts,

[0017] Modified methyl nadic anhydride MNA-10 28-32 parts,

[0018] Curing accelerator 0.3-0.5 parts;

[0019] (2) The mixture obtained in step (1) is placed in a vacuum bag, vacuumized to a relative vacuum degree of ≤-0.090 MPa, and then placed in a hot press tank for multi-stage temperature curing treatment;

[0020] The multi-stage temperature rising curing treatment is a four-stage temperature rising curing, the first stage temperature rising curing is to rise to 100°C at a temperature rising speed of 1.9-2.1 ℃ / min, and to pressurize to 0.5 MPa at a pressure rising speed of 0.04-0.06 MPa / min after the temperature reaches 80°C, when the temperature reaches 100°C and the pressure reaches 0.5 MPa, the temperature and pressure are maintained for 58-62 min; after the time reaches, the second stage temperature rising curing is to rise to 120°C at a temperature rising speed of 1.9-2.1 ℃ / min, and to pressurize to 0.7 MPa at a pressure rising speed of 0.04-0.06 MPa / min after the temperature reaches 110°C, when the temperature reaches 120°C and the pressure reaches 0.7 MPa, the temperature and pressure are maintained for 118-122 min; after the time reaches, the third stage temperature rising curing is to rise to 140°C at a temperature rising speed of 1.9-2.1 ℃ / min, and to pressurize to 1.2 MPa at a pressure rising speed of 0.04-0.06 MPa / min after the temperature reaches 130°C, when the temperature reaches 140°C and the pressure reaches 1.2 MPa, the temperature and pressure are maintained for 178-182 min; after the time reaches, the fourth stage temperature rising curing is to rise to 160°C at a temperature rising speed of 1.9-2.1 ℃ / min, when the temperature reaches 160°C, the temperature and pressure are maintained for 238-242 min;

[0021] (3) multi-stage temperature rising curing treatment is followed by multi-stage temperature falling treatment, and the resin cured product is obtained by taking out finally;

[0022] The multi-stage temperature falling treatment is a three-stage temperature falling, the first stage temperature falling is to fall to 100°C at a temperature falling speed of 0.9-1.1 ℃ / min under the condition of pressure maintaining, when the temperature reaches 100°C, the temperature and pressure are maintained for 118-122 min; after the time reaches, the second stage temperature falling is to fall to 50°C at a temperature falling speed of 0.9-1.1 ℃ / min under the condition of pressure maintaining, when the temperature reaches 50°C, the temperature and pressure are maintained for 118-122 min; the third stage temperature falling is to fall to normal temperature at a temperature falling speed of 0.9-1.1 ℃ / min, and to fall to normal pressure at a pressure falling speed of 0.04-0.06 MPa / min, and the resin cured product is obtained by taking out from the autoclave after the normal temperature and normal pressure are reached and the vacuum bag is removed.

[0023] In the present text, the hydantoin epoxy resin is a kind of commercially available conventional epoxy resin containing a hydantoin ring (five-membered diazole ring), and the cured product thereof usually has excellent heat resistance, weather resistance and high-temperature dielectric performance, and the person skilled in the art can select the hydantoin epoxy resin based on the conventional hydantoin epoxy resin used in the electrical field, and preferably the hydantoin epoxy resin suitable for being applied to the high-voltage transmission bus is recorded in the prior art.

[0024] In the present application, the benzoxazine resin is a kind of conventional thermosetting resin containing nitrogen and oxygen six-membered oxazine ring in the molecular structure, and the cured product thereof usually has the characteristics of heat resistance, flame retardance, low porosity, near-zero shrinkage, etc. Those skilled in the art can select the benzoxazine resin commonly used in the electrical field based on the benzoxazine resin commonly used in the electrical field, and preferably select the benzoxazine resin suitable for high-voltage transmission bus described in the prior art.

[0025] In the present application, the curing accelerator is a conventional functional chemical additive for accelerating the crosslinking reaction of the polymer material, and those skilled in the art can query the curing accelerator suitable for use based on the hydantoin epoxy resin and the benzoxazine resin specified in the present application, for example, including but not limited to 2-ethyl-4-methylimidazole (CAS: 931-36-2) and the like.

[0026] In one of the technical solutions, the mixture in step (1) can further include fillers or / and auxiliaries commonly used in epoxy resins or hybrid resins to achieve further functional expansion / process assistance / enhancement of the cured product. The specific selection of fillers or / and auxiliaries can be referred to the prior art or existing literature, such as antioxidants, flame retardants, coupling agents, etc. It should be noted that the raw materials can or can not include fillers or / and auxiliaries commonly used in epoxy resins or hybrid resins.

[0027] It should be noted that the mixture in step (2) is placed in a vacuum bag, so that the resin cured product obtained in step (3) has different forms. The mixture can be injected into the mold or the bare bus in the form of filling, and then the whole is placed in the vacuum bag. Alternatively, the epoxy glass cloth is impregnated in the mixture, and the obtained epoxy glass cloth prepreg is placed in the vacuum bag.

[0028] In one of the preferred technical solutions, the mixture in step (2) is placed in a heat press tank for multi-stage temperature rising curing treatment, and the multi-stage temperature rising curing treatment in step (3) is followed by multi-stage temperature dropping treatment. During the above treatment process, the vacuum bag is in communication with the vacuum device outside the heat press tank, and the vacuum degree is continuously maintained at ≤-0.090 MPa.

[0029] One of the points of the present application is that in order to make the cured product of the filling resin for water-cooled transmission bus have the advantages of hydantoin epoxy resin and benzoxazine resin, it has good dielectric properties, heat resistance and mechanical properties. Through comparative experiments, it is found that the mixed resin composed of hydantoin epoxy resin and benzoxazine resin in a certain proportion has different suitable curing temperature windows. Under the condition that the two have different suitable curing temperature windows, it is found that the synergistic multi-stage temperature rising curing treatment and multi-stage temperature dropping treatment have better dielectric loss and electrical strength performance compared with one-step temperature rising and one-step temperature dropping.

[0030] On the other hand, based on the practical application of the above-mentioned water-cooled transmission busbar filling resin curing process, the present invention also provides a method for preparing a high-voltage, high-current transmission busbar, which mainly includes the following steps:

[0031] (I) An initial busbar with cooling water channels is prepared by hot pressing and forming electrical conductor materials and opening holes;

[0032] (II) Fill the cooling water channel of the initial busbar obtained in step (I) with quartz sand and seal the outlets at both ends. Then bend it into shape and remove the quartz sand to obtain the shaped busbar.

[0033] (III) The surface of the molded busbar obtained in step (II) is sandblasted, and then modified epoxy adhesive is applied to the surface. After fixing, polyimide film and / or epoxy glass cloth prepreg are wrapped around it and then placed in a vacuum bag. The busbar is then subjected to multi-stage heating and curing treatment and multi-stage cooling treatment according to the above-mentioned water-cooled transmission busbar filling resin curing process. The busbar is then taken out and used as a wrapped busbar for later use.

[0034] (IV) The coated busbar obtained in step (III) is processed by the above-mentioned water-cooled transmission busbar with filling resin curing process, wherein the mixture is injected into the gap between the winding material and the formed busbar inside the coated busbar, and then put into a vacuum bag for multi-stage heating curing and multi-stage cooling treatment to prepare a bare busbar.

[0035] (V) The bare busbar obtained in step (IV) is covered with a shielding armor layer, and then treated according to the above-mentioned water-cooled transmission busbar filling resin curing process. The mixture is injected into the gap between the bare busbar and the shielding armor layer, and then put into a vacuum bag for multi-stage heating curing and multi-stage cooling treatment to prepare a high-voltage high-current transmission busbar.

[0036] In this document, the initial busbar with cooling water channels described in step (I) can refer to the specifications required for existing high-voltage transmission busbars in the art for its specific shape and size. In one technical solution, the cross-sectional shape of the initial busbar with cooling water channels includes, but is not limited to, rectangles, sectors, triangles, circles, ellipses, etc., with the short side or short radius of the cross-section ≥ 60 mm and the long side or long radius ≥ 100 mm; the cooling water channels are preferably through holes with a circular cross-section, a diameter of 20~30 mm, and 1~6 cooling water channels are provided.

[0037] In one of the technical solutions, the electrical conductor material described in step (I) is hot-pressed and has through holes. In the industrial process of this technical field, it is possible to directly purchase pre-opened semi-finished products and further prepare the initial busbar with cooling water channels of the target specifications through hot pressing.

[0038] In one preferred embodiment, when the initial busbar with cooling channels obtained in step (I) has sharp edges, the edges are further rounded with a radius of ≥2 mm to avoid charge concentration and reduce the impact on the insulation layer.

[0039] In this document, the specific shape and size of the formed busbar after bending in step (II) can refer to the specifications required for existing high-voltage transmission busbars in this field. In one technical solution, the shape of the formed busbar includes, but is not limited to, L-shaped, Ω-shaped, Z-shaped, U-shaped, etc.

[0040] One of the inventive points of this invention is that in step (II), quartz sand is filled to prevent the cooling water channel from deforming during the subsequent bending and forming process, thus solving the problem of cooling water channel deformation when bending a large cross-section busbar.

[0041] In one preferred embodiment, to reduce the deformation rate of the cooling water channel cross-section after bending, the quartz sand particle size is 20-100 mesh.

[0042] In this paper, the wrapped busbars obtained in step (III) can be further integrated and wrapped with epoxy glass cloth prepreg to finally prepare an integrated busbar. For example, when two wrapped busbars are used, the final high-voltage, high-current transmission busbar can be a two-stage busbar; when four wrapped busbars are used, the final high-voltage, high-current transmission busbar can be four integrated busbars for three-phase AC transmission.

[0043] In this paper, the winding process described in step (III) can refer to the existing high-voltage transmission bus manufacturing process, such as the constant tension winding process based on a constant tension control system.

[0044] In one technical solution, the winding of polyimide film and / or epoxy glass cloth prepreg in step (III) specifically involves first winding 1-2 layers of 0.025 mm thick polyimide film, followed by winding 0-2 layers of 2-16 mm thick epoxy glass cloth prepreg. Further, to prepare the integrated busbar, it is preferable to first wind 1-2 layers of 0.025 mm thick polyimide film around the molded busbar coated with modified epoxy adhesive, then wind 0-2 layers of 2-16 mm thick epoxy glass cloth prepreg, and after multi-stage heating and curing treatment and multi-stage cooling treatment, arrange and fix it before winding 1-2 layers of 2-16 mm thick epoxy glass cloth prepreg as a whole.

[0045] In one technical solution, it is preferable to use the polyimide film and / or epoxy glass cloth prepreg described in step (III), and after multi-stage heating and curing treatment and multi-stage cooling treatment, to perform a surface smoothing treatment on the coated busbar to reduce the porosity that may be generated in subsequent processes. Similarly, after the bare busbar is prepared in step (IV), its surface is also smoothed.

[0046] In one preferred embodiment, the epoxy glass cloth prepreg in step (III) contains a total content of hydantoin epoxy resin and benzoxazine resin of 45-55%.

[0047] In this paper, the injection method of the mixture described in steps (IV) and (V) can refer to the preparation process of high voltage transmission bus in the prior art, such as injection filling by vacuum suction, so as to minimize porosity.

[0048] In one technical solution, the injection of the mixture in steps (IV) and (V) is performed by vacuum suction, and the flow rate is controlled at 5~20 ml / min. More preferably, after the mixture is injected, the vacuum degree is maintained at ≤-0.090 MPa for at least 30 min.

[0049] In general, to ensure the product qualification rate throughout the entire preparation process, intermediate tests can be conducted on intermediate products in the preparation process of high-voltage transmission busbars, referring to the intermediate tests in the existing technology. For example, the voltage withstand test and porosity test can be conducted on the coated busbar obtained in step (III), and the voltage withstand test and porosity test can be conducted on the bare busbar obtained in step (IV).

[0050] The present invention has the following beneficial effects:

[0051] 1. This invention provides a resin curing process for water-cooled transmission busbars. By using a specific ratio of mixed resins, a multi-stage heating and curing process and a multi-stage cooling process are carried out based on autoclave molding, thereby obtaining resin cured products and epoxy glass cloth composite materials with good dielectric and mechanical properties.

[0052] 2. The present invention also provides a method for preparing a high-voltage, high-current transmission busbar. By introducing a quartz sand filling and shaping process, the cross-sectional area of ​​the busbar is reduced by ≤1% after bending, the water channel is unblocked, the inner wall is wrinkle-free, the heat dissipation efficiency is stable, and the bending forming accuracy is high.

[0053] 3. This invention combines the resin curing process for water-cooled transmission busbars with the synergistic effect of the winding insulation layer to prepare a high-voltage, high-current transmission busbar with a withstand voltage ≥65kV AC, a tracking index (PTI) ≥600, a long-term heat resistance temperature ≥155℃, and a service life ≥20 years. More advantageously, the entire production process utilizes vacuum technology and autoclave molding technology in multiple places, resulting in the following beneficial outcomes: a dense insulation layer without bubbles or cracks, and partial discharge of the insulation layer ≤50PC@26KVAC.

[0054] 4. By utilizing the water-cooled transmission busbar with a resin-filled curing process, the cured product exhibits excellent dielectric and mechanical properties, strong adhesion to conductors and insulation layers, and no cracking or peeling. Attached Figure Description

[0055] Figure 1 The bar chart shows the comparison of the dielectric loss performance of the cured products prepared in Example 1 and Comparative Examples 1-11 of this invention.

[0056] Figure 2 This is a bar chart comparing the electrical strength properties of the cured products prepared in Example 1 and Comparative Examples 1-11 of the present invention.

[0057] Figure 3 This is a schematic diagram of the overall preparation method process of Embodiment 2 of the present invention.

[0058] Figure 4 This is a schematic diagram of the disassembled structure of the two-pole bare busbar prepared in Example 2 of the present invention.

[0059] Figure 5 This is a schematic diagram of the cross-sectional structure of the high-voltage, high-current transmission bus prepared in Embodiment 3 of the present invention.

[0060] Figure 6 This is a photograph of the autoclave used in Embodiment 1 of the present invention.

[0061] In the diagram, 1 is the molding busbar, 2 is the polyimide film layer, 3 is the epoxy glass cloth prepreg layer, 4 is the cooling water channel, and 5 is the shielding armor layer. Detailed Implementation

[0062] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be construed as limiting the scope of this application. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all commercially available conventional products. This application should not be construed as being limited to the specific embodiments described.

[0063] Example 1

[0064] This embodiment describes a resin curing process for a water-cooled transmission bus, including the following steps:

[0065] (1) The following raw materials, by mass parts, are mixed together to form a mixture:

[0066] 40 parts of Hain epoxy resin MHR-070 (Hubei Longxin Chemical Co., Ltd.)

[0067] 30 parts of benzoxazine resin CB2900 (Chengdu Keyi Polymer Technology Co., Ltd.)

[0068] Modified methyl nadic anhydride MNA-10 (Jingjiang Yongtaifeng Chemical Co., Ltd.) 30 parts

[0069] 0.4 parts of 2-ethyl-4-methylimidazole;

[0070] (2) Place the mixture obtained in step (1) into a vacuum bag, evacuate it to a relative vacuum degree ≤ -0.090 MPa, and then place it in an autoclave (DN1500×4000, Zhucheng Antai Machinery Co., Ltd., such as...). Figure 6 (As shown) undergoes multi-stage heating and curing treatment;

[0071] The multi-stage temperature-curing process consists of four stages, as shown in Table 1 below:

[0072] Table 1: Parameters of the Four-Stage Temperature-Increasing Curing Process

[0073]

[0074] (3) After multi-stage heating and curing treatment, multi-stage cooling treatment is carried out, and finally the resin cured product is taken out as a sample.

[0075] The multi-stage cooling process consists of three stages, as shown in Table 2 below:

[0076] Table 2: Three-stage cooling process parameters

[0077]

[0078] Comparative Examples 1-11

[0079] Comparative Examples 1 to 11 are comparative experiments based on the process of Example 1. The variables are multi-stage heating curing treatment, multi-stage cooling treatment, and whether the relative vacuum degree is maintained at ≤-0.090 MPa during the above treatments. Resin cured products were prepared as comparative samples.

[0080] The cured resin obtained in Example 1 was designated as serial number 1, and the cured resins obtained in Comparative Examples 1 to 11 were designated as serial numbers 2 to 12, respectively. The dielectric loss (%) and electrical strength (MV / mm) of the cured resins obtained in Example 1 and Comparative Examples 1 to 11 were tested according to national standards GB / T1409-2006 and GB / T1408.1-2016, respectively. Specific variable parameters and test results are shown in Table 3 below. Figure 1 , Figure 2 As shown:

[0081] Table 3: Summary of process variable parameters and test results for serial numbers 1-12

[0082]

[0083] In the table, "-" indicates that the heating / curing or cooling treatment is not performed in that stage. For example, in item 11 (Comparative Example 10), the heating / curing process involves heating to 100°C at a rate of 2°C / min, and then pressurizing to 0.5 MPa at a rate of 0.05 MPa / min after reaching 80°C. Once the temperature reaches 100°C and the pressure reaches 0.5 MPa, the temperature and pressure are maintained for 180 min. After this time, the temperature is increased to 160°C at a rate of 2°C / min, and then pressurized to 1.2 MPa at a rate of 0.05 MPa / min after reaching 130°C. Once the temperature and pressure reach 160°C and 1.2 MPa, the temperature and pressure are maintained for 420 min. The cooling process involves cooling to 50°C at a rate of 1°C / min under pressure. Once the temperature reaches 50°C, the temperature and pressure are maintained for 240 min. After the set time is reached, cool down to room temperature at a rate of 1 °C / min, and then depressurize to atmospheric pressure at a rate of 0.05 MPa / min. Once room temperature and atmospheric pressure are reached, remove the product from the autoclave and remove the vacuum bag to obtain the cured resin. The other comparative examples should be performed in the same manner.

[0084] In the table, vacuum level is indicated by "-" to mean that the external vacuum equipment of the autoclave is not turned on, and the relative vacuum level is not maintained at ≤-0.090 MPa. For example, in serial number 4 (Comparative Example 3), the relative vacuum level is maintained at ≤-0.090 MPa throughout the heating and curing process, but during the cooling process, the vacuum equipment is turned off, and the relative vacuum level is not maintained at ≤-0.090 MPa. The other comparative examples are performed in the same manner.

[0085] Example 2

[0086] Example 2 provides a method for preparing a high-voltage, high-current transmission bus, which mainly includes the following steps:

[0087] (I) Select 6063 aluminum alloy ingots with a purity ≥99.7%, place them in a homogenizing furnace and keep them at 480 ℃ for 8 hours, then send them into a 2000-ton CNC extrusion press. Preheat the die to 380 ℃ and extrude a 200 mm × 100 mm rectangle at a speed of 1 m / min. After opening holes, stretching and straightening, cutting and rounding, the initial busbar with cooling water channels is prepared.

[0088] (II) Fill the cooling water channels of the initial busbar obtained in step (I) with 50-mesh quartz sand, tamp it down, and seal both ends with bolts. After preheating to 180 ℃, place it into a special arc bending die of a 3600T hydraulic press and bend it at a pressure speed of 0.8 mm / s with a bending radius of 220 mm. Remove the quartz sand with 0.8 MPa high-pressure air. The cross-sectional area of ​​the cooling water channel is reduced by no more than 0.8% by a laser 3D scanner. The roundness tolerance of the cooling water channel is 0.1 mm and it is unobstructed. The formed busbar is then obtained.

[0089] The reduction ratio of the cross-sectional area of ​​the cooling water channel is calculated as (1 - cross-sectional area of ​​the cooling water channel after bending ÷ cross-sectional area of ​​the cooling water channel before bending) × 100%;

[0090] (III) The surface of the molded busbar obtained in step (II) is sandblasted to control the roughness Ra=1.4 μm. Then, a modified epoxy adhesive is applied to the surface and fixed. After fixing, two layers of 0.025 mm thick polyimide film are wound using a constant tension winding machine with a tension of 1.5 N / cm. Then, epoxy glass cloth prepreg (resin content 50%) is wound to a thickness of 6 mm. During winding, far-infrared heating is maintained at 90 ℃ with a tension of 4 N / cm.

[0091] The tubes are placed in a vacuum bag and subjected to multi-stage heating and curing treatment and multi-stage cooling treatment according to Example 1 above. The tubes are then removed and used as the coated busbars.

[0092] Then, the surface of the wrapped busbar is smoothed. After passing the voltage withstand test and porosity test, the two wrapped busbars are fixed and positioned, and then the whole is wrapped with epoxy glass cloth prepreg to a thickness of 6 mm to serve as the two-pole wrapped busbars.

[0093] (IV) The bipolar coated busbar obtained in step (III) is processed according to Example 1, wherein the mixture is injected into the gap between the winding material and the formed busbar in the bipolar coated busbar by vacuum suction, and then put into a vacuum bag for multi-stage heating and curing treatment and multi-stage cooling treatment to prepare the bipolar bare busbar.

[0094] (V) After the two bare busbars obtained in step (IV) pass the surface smoothing treatment, voltage withstand test and porosity test, they are covered with a 1 mm thick shielding armor layer (SU304). Then they are processed according to Example 1, wherein the mixture is injected into the gap between the two bare busbars and the shielding armor layer by vacuum suction. Then they are put into a vacuum bag for multi-stage heating and curing treatment and multi-stage cooling treatment to prepare a high voltage and high current transmission busbar with two busbars.

[0095] like Figure 3 The diagram shows a schematic representation of the overall preparation method process in Example 2.

[0096] like Figure 4 The diagram shows a disassembled structure of the bare busbars prepared in Example 2. In the diagram, the molded busbar 1 is wrapped with a polyimide film layer 2 and an epoxy glass cloth prepreg layer 3. Then, the two wrapped busbars are wrapped with the epoxy glass cloth prepreg layer 3 as a whole.

[0097] Comparative Example 12

[0098] Comparative Example 12 is based on the preparation method of Example 2, but in step (II), quartz sand was not filled in the cooling water channel and the bending was performed directly. The maximum reduction in the cross-sectional area of ​​the cooling water channel was 12%, as detected by a laser three-dimensional scanner.

[0099] Example 3

[0100] Example 3 is based on the preparation method of Example 2, and a high-voltage, high-current transmission busbar with integrated four busbars for three-phase AC transmission is prepared. The difference from Example 2 is that after fixing in step (III), two layers of 0.025mm thick polyimide film are wound using a constant tension winding machine with a tension of 1.5 N / cm; then, after fixing and positioning the two busbars wound with polyimide film, epoxy glass cloth prepreg is wound around the whole body to a thickness of 6 mm, and then placed in a vacuum bag for multi-stage heating and curing treatment and multi-stage cooling treatment according to Example 1 above. The busbar is then taken out as the two-pole busbar after coating.

[0101] Then, the surfaces of the two coated busbars are smoothed. After passing the voltage withstand test and porosity test, the two coated busbars are fixed in position and then wrapped with epoxy glass cloth prepreg to a thickness of 6 mm to form an integrated coated busbar.

[0102] like Figure 5 As shown, a schematic diagram of the cross-sectional structure of the high-voltage, high-current transmission busbar prepared in this embodiment 3 is presented. In the figure, the molded busbar 1 has multiple cooling water channels 4, and two adjacent left and right molded busbars 1 are wrapped with a polyimide film layer and an epoxy glass cloth prepreg layer 3. All four molded busbars 1 are wrapped with an epoxy glass cloth prepreg layer 3 and a shielding armor layer 5.

[0103] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A resin curing process for water-cooled transmission busbars, characterized in that... Includes the following steps: (1) The following raw materials, by mass parts, are mixed together to form a mixture: 38-42 parts of Hein epoxy resin 28-32 parts of benzoxazine resin, 28-32 parts of modified methylnadic anhydride MNA-10 0.3-0.5 parts of curing accelerator; (2) Place the mixture obtained in step (1) into a vacuum bag, evacuate it to a relative vacuum degree ≤ -0.090 MPa, and then place it in a thermostatic precipitator for multi-stage heating and curing treatment; The multi-stage temperature-curing process consists of four stages. The first stage involves heating to 100°C at a rate of 1.9–2.1°C / min, and then pressurizing to 0.5 MPa at a rate of 0.04–0.06 MPa / min after reaching 80°C. Once both the temperature and pressure reach 100°C and 0.5 MPa, the pressure is maintained for 58–62 minutes. The second stage involves heating to 120°C at a rate of 1.9–2.1°C / min, and then pressurizing to 0.7 MPa at a rate of 0.04–0.06 MPa / min after reaching 110°C. This process is maintained for 118–122 minutes. Finally, the third stage involves heating to 140°C at a rate of 1.9–2.1°C / min, and then pressurizing to 130°C and 0.5 MPa. After reaching 140 ℃, the pressure is increased to 1.2 MPa at a rate of 0.04~0.06 MPa / min. When the temperature reaches 140 ℃ and the pressure reaches 1.2 MPa, the pressure is maintained for 178~182 min. After the time is up, the fourth stage of curing is carried out by increasing the temperature to 160 ℃ at a rate of 1.9~2.1 ℃ / min. When the temperature reaches 160 ℃, the pressure is maintained for 238~242 min. (3) After multi-stage heating and curing treatment, multi-stage cooling treatment is carried out, and finally the resin cured product is taken out. The multi-stage cooling process consists of three stages. The first stage involves cooling to 100°C at a rate of 0.9–1.1°C / min under pressure, and then holding the temperature and pressure for 118–122 minutes. After this time, the second stage involves cooling to 50°C at a rate of 0.9–1.1°C / min under pressure, and then holding the temperature and pressure for 118–122 minutes. The third stage involves cooling to room temperature at a rate of 0.9–1.1°C / min, and then depressurizing to atmospheric pressure at a rate of 0.04–0.06 MPa / min. Once room temperature and pressure are reached, the resin is removed from the autoclave, and the vacuum bag is removed to obtain the cured resin.

2. The resin curing process for water-cooled transmission busbars according to claim 1, characterized in that: The curing accelerator includes 2-ethyl-4-methylimidazole.

3. The resin curing process for water-cooled transmission busbars according to claim 1, characterized in that: In step (2), the vacuum bag is placed in the autoclave for multi-stage heating and curing treatment, and in step (3), the vacuum bag is placed in the autoclave for multi-stage cooling treatment. During the above treatment process, the vacuum bag is connected to the vacuum equipment outside the autoclave and the vacuum is continuously pumped to maintain a relative vacuum degree of ≤-0.090 MPa.

4. A method for manufacturing a high-voltage, high-current transmission busbar, characterized in that... The main steps include: (I) An initial busbar with cooling water channels is prepared by hot pressing and forming electrical conductor materials and opening holes; (II) Fill the cooling water channel of the initial busbar obtained in step (I) with quartz sand and seal the outlets at both ends. Then bend it into shape and remove the quartz sand to obtain the shaped busbar. (III) The surface of the molded busbar obtained in step (II) is sandblasted, and then a modified epoxy adhesive is applied to the surface. After fixing, polyimide film and / or epoxy glass cloth prepreg are wrapped around it and then placed in a vacuum bag. The water-cooled transmission busbar is cured with filling resin according to the process described in claim 1 and then subjected to multi-stage heating and curing treatment and multi-stage cooling treatment. The busbar is then taken out and used as a wrapped busbar for later use. (IV) The coated busbar obtained in step (III) is processed by the water-cooled transmission busbar described in claim 1 using a resin-filling curing process, wherein the mixture is injected into the gap between the winding material and the formed busbar inside the coated busbar, and then placed in a vacuum bag for multi-stage heating curing and multi-stage cooling treatment to prepare a bare busbar. (V) The bare busbar obtained in step (IV) is covered with a shielding armor layer, and then treated with a resin-filled curing process according to the water-cooled transmission busbar described in claim 1, wherein the mixture is injected into the gap between the bare busbar and the shielding armor layer, and then placed in a vacuum bag for multi-stage heating and curing treatment and multi-stage cooling treatment to prepare a high-voltage, high-current transmission busbar.

5. The preparation method according to claim 4, characterized in that: Step (I) also includes rounding the edges of the initial busbar, with a radius of ≥2 mm.

6. The preparation method according to claim 4, characterized in that: The quartz sand particle size mentioned in step (II) is 20~100 mesh.

7. The preparation method according to claim 4, characterized in that: The wrapped busbars obtained in step (III) can be further integrated and wrapped with epoxy glass cloth prepreg.

8. The preparation method according to claim 4, characterized in that: The winding of polyimide film and / or epoxy glass cloth prepreg in step (III) specifically involves first winding 1 to 2 layers of 0.025 mm thick polyimide film, followed by winding 0 to 2 layers of 2 to 16 mm thick epoxy glass cloth prepreg.

9. The preparation method according to claim 4, characterized in that: The epoxy glass cloth prepreg described in step (III) has a total content of hydantoin epoxy resin and benzoxazine resin of 45-55%.

10. The preparation method according to claim 4, characterized in that: The mixture described in steps (IV) and (V) is injected using a vacuum suction method, and the flow rate is controlled at 5~20 ml / min.

11. The high-voltage, high-current transmission bus prepared by the method for preparing a high-voltage, high-current transmission bus as described in claim 4.

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