In the process of winding and embedding the motor coil, […]
In the process of winding and embedding the motor coil, the mechanical force acts on the enameled wire, such as tensile force, friction force and bending force during winding. There is friction in the embedding process. There is inter-turn friction caused by vibration during motor operation. If the core wire or paint film of the Copper Winding Wire cannot meet the requirements, the above-mentioned mechanical forces will bring different degrees of damage. Therefore, it is important to establish various mechanical performance tests on the basis of simulating the use requirements.
Elongation rate is established by simulating the winding process of enameled wire. Its purpose is to control the adaptability of wire to winding coil and ensure smooth operation. After the enameled wire is stretched, its adhesion, scratch resistance, elasticity, thermal shock and solvent resistance will all decline to vary degrees.
Rebound angle test:
The softness of copper winding wire is an important index in use. The coil wound on the wire mould, such as enameled wire, will rebound and deform due to poor flexibility, which will directly affect the processing quality and labour productivity of the coil winding.
Flexibility and adhesion:
Flexibility and adhesion tests include winding, stretching, rapid breaking and peeling twisting tests. Enameled wires are subjected to two external forces when winding coils. (1) Tensile force. If the elasticity of the paint film is insufficient, the elongation of the paint film after being stressed cannot keep up with the elongation of the conductor, and the paint film will crack. (2) Bending force: the paint film on the outer edge is elongated after bending, and the paint film on the inner edge is compressed. If the elasticity is not good, the paint film will also crack. Fine lines are easy to be stretched and tested by elongation method. Thick lines are greatly affected by bending and are tested by the winding method.
Pressure or friction force will act on the enameled wire during winding and moulding of coils, the embedding of wires and operation of electrical products. The scratch-resistance of the paint film is expressed by the number of times the paint film resists scratching or the scratch force under the action of external force.
Heat resistance test:
Heat resistance is an important index, which is of great significance to motors and components or windings with severe temperature rise requirements. It directly affects the design and use of electrical equipment. The temperature rise of electrical equipment is limited by enameled wires and other insulating materials used. If enameled wires with high heat resistance and matching materials can be used, good stability can be obtained under the condition of unchanged structure, or the energy-saving effects of reducing external dimensions, weight, non-ferrous metals and other material consumption can be achieved under the condition of keeping power unchanged.
Thermal ageing test:
It takes six months to one year (UL test) to measure the thermal performance of enameled wire by thermal life assessment method. The ageing test lacks application simulation, but it is still significant to control the quality of paint and the baking degree of the paint film in the production process of copper winding wires.
Thermal shock test:
Heat shock resistance test is to study the tolerance of enameled wire film to heat under mechanical stress.
Heat-resistant softening breakdown test:
In the coil, the lower enameled wire is subjected to the pressure caused by the tension of the upper enameled wire. If the enameled wire is heated and softened during the pre-drying or drying process of impregnation or during operation at high temperature, the paint film will gradually be squeezed thin under the pressure, which may result in turn-to-turn short circuit of the coil.