Brief description of the structure of enameled wire
The structure of enameled wire is divided into two parts: conductor and insulation. According to the conductor material, it can be divided into copper, aluminum, alloy, etc., and according to the shape of the conductor, it can also be divided into round wire, flat wire, hollow wire, etc. According to the insulating material, it is mainly divided into enameled wire, wrapping wire and inorganic insulated wire. Amidoimide paints, aromatic polyimide paints, polyamideimide paints (Figure 3), polyester-amide-imide paints, self-adhesive paints, direct solderable paints, composite paints (Figure 3) 4) etc.
The difference between enameled wire round wire and flat wire
1. Compared with round wire and flat wire, the slot full rate is higher (Figure 5). Under the same winding space conditions, the slot full rate of enamelled copper flat wire can reach more than 95%, which solves the problem that the coil is difficult to improve for a long time problem, so that the resistance is reduced and the capacitance is larger, which can better meet the requirements of high-capacity and high-load applications.
2. Under the same cross-sectional area, it has a larger surface area than the round enameled wire, and its heat dissipation area also increases accordingly.
3. Compared with round wire, flat enamelled copper wire takes up less space than the coil of enamelled copper round wire, which can meet the design requirements of electronic and motor products with smaller volume, lighter weight and higher power density.
4. The thickness of the corner paint film is similar to that of the top paint film (Figure 6), which is beneficial to maintain the insulation of the user's coil.
Enameled wire production process
The enamelling process is to coat the wire with one or more uniform paint films with a certain thickness. Different wires have different processes for the same paint film. Similarly, different paint liquids also have different processes for the same wire. The equipment, the size of the wire specification, and the method of "laying out and annealing" are also different. Taking polyester enamelled copper round wire as an example, its production process has the following processes:
In the enameled wire production process, in order to ensure the quality and performance of the enameled wire, experiments must be carried out. The types of experiments include type experiments, sampling experiments, and routine experiments. The type test is the test conducted by the manufacturer before providing a certain winding wire in the product standard. The characteristic of the test is that it will not be redone after it has been done once, but the test should be repeated when the material, structure and main process of the winding wire are changed and the performance of the winding wire is affected, or it should also be carried out in accordance with other regulations in the product. stipulated. The type test items of flat wire include size, elongation, springback angle, flexibility and adhesion, solvent resistance, transformer oil resistance, resistance, breakdown voltage, thermal shock, dielectric loss coefficient, and temperature index.
Sampling test is a test in which the manufacturer extracts winding wires into shafts according to the manufacturing batch and cuts samples from them. The sampling test items for flat wires include size, elongation, springback angle, flexibility and adhesion, and solvent resistance. , Breakdown voltage at room temperature, thermal shock.
The routine test is the test conducted by the manufacturer on all the finished winding wires. The test items of the flat wire include appearance and packaging.
Our common experimental items include size measurement, mechanical performance experiment, chemical performance experiment, electrical performance experiment, and thermal performance experiment. Dimensional measurement includes insulation thickness measurement, external dimension measurement, conductor out-of-roundness, flat wire fillet, etc.
Mechanical properties tests included elongation, resilience (instrument Figure 7), scratch resistance (instrument Figure 8) and thermal bonding, flexibility and adhesion. The elongation rate reflects the plastic denaturation of the material, which is used to assess the ductility of the enameled wire. The flexibility includes winding and stretching, that is, the allowable stretching deformation of the paint film with the stretching deformation of the conductor without breaking. The adhesion includes sharp pulling Breaking, peeling, mainly to assess the adhesion ability of the paint film to the conductor. Scratch resistance test reflects the strength of the paint film against mechanical scratches.
The chemical performance test items include solvent resistance, refrigerant resistance, direct solderability, hydrolysis resistance and transformer oil resistance. Solvent resistance refers to the impregnation process after the general enameled wire is wound into a coil. The solvent in the impregnation paint has an effect on the paint film. Different degrees of swelling are more severe at higher temperatures. Freezing resistance is expressed by the number of extracts and breakdown voltage of the enameled wire paint film placed in the refrigerant. Direct solderability is the removal of the tin film by immersing the sample in a solder tank And the time required to coat the tin layer, resistance to hydrolysis reaction, changes in appearance and adhesion of samples in water-containing transformer oil under high temperature and pressure, and resistance to transformer oil is the breakdown of samples in transformer oil under high temperature and pressure voltage and flexibility.
The electrical performance experiment includes resistance, breakdown voltage, dielectric loss factor, paint film continuity, and pinhole experiment (instrument Figure 9). The breakdown voltage refers to the ability of the enameled wire paint film to withstand the voltage load. The paint film continuity is used The number of pinholes in the paint film is detected by the winding wire per unit length through the electrical test circuit. The dielectric loss factor means that the sample is used as a capacitor, the paint film is used as a dielectric, the conductor is one electrode of the capacitor, and the conductive medium is used as the other electrode. The capacitor is connected to the circuit , the circuit measures the capacitive and resistive components at a specified frequency, and the pinhole experiment represents the number of defects observed in the insulation after salt water treatment.
Thermal performance experiments include thermal shock, softening breakdown, temperature index, weight loss, thermal shock test response to the ability of the sample to withstand temperature after being stretched or coiled or bent on a round rod, softening breakdown performance is a measure of enameled wire The ability of the paint film to withstand thermal deformation under the action of mechanical force, that is, the ability of the pressured paint film to plasticize and soften at high temperature, the weight loss test reflects the performance related to the curing degree of the enameled wire paint film.
Enameled wire production standards and national standard model identification method
In order to adapt to different national conditions in various countries, enameled wires have formulated different standards in different countries. In my country, enameled round wires are mainly applicable to GBT 6109-2008, enameled copper flat wires are applicable to GBT 7095-2008, and American standards mainly refer to MW 1000 -2003 electromagnetic wire, the Japanese standard refers to JIS C 3202-1994, and the International Electrotechnical Commission refers to IEC 60317.
National standard model identification method:
Product name: composed of "temperature index" + "thickness of insulating varnish layer" + "name of insulating varnish" + "enamelled/paper covered wire, etc.", such as: QZY/XY-2/200 means the primer in the national standard (GB) It is polyesterimide, the top coat is polyamide-imide paint, and the enamelled round wire with a grade 2 paint film thickness and temperature rating of 200.
Japanese standard model representation method:
For example: 1EI/AIW/A/200 means that the Japanese standard (JIS) primer is polyesterimide, and the topcoat is polyamideimide grade 1 paint film thickness and temperature grade aluminum wire of 200.
The US model representation method uses a specific specification number to indicate the type of paint film and the specific specification number of the heat level, and the specific specification number should refer to the MW 1000-2003 standard, such as MW 79-C, which means a direct-solderable polyurethane enamelled copper round wire with a heat level of 155 (thin paint film, thick paint film and thicker paint film).
