The winding assembly process for small motors has long relied on manual operation, resulting in high labor intensity, low production efficiency, and incompatibility with other motor manufacturing processes, making it unsuitable for mass production. Therefore, the mechanization and automation of loose winding assembly is the main trend in the current development of small motor winding manufacturing processes. In recent years, my country has made some progress in the mechanization and automation of loose winding assembly for small motors, and automated assembly equipment has been gradually introduced into some motor manufacturing enterprises.
The mechanical assembly of small motor windings is divided into two methods: direct method and indirect method. Ms. Can will share some information about this with you today.
1. Direct embedding method
The direct winding method, also known as the direct winding method, involves directly winding the conductor into the slots of the iron core. It is often used for embedding AC rotors or DC armature windings. In practical applications, rotor or armature winding unwinding machines are generally equipped with automatic turn counting, automatic slot skipping, and automatic workpiece clamping devices, resulting in a relatively complex structure.
2. Indirect embedding method
The indirect method involves winding the conductor into a coil and then spreading it into the slots of the iron core. This method is often used for stator windings that are laid out in a loose configuration. Common methods include the pull-in method and the electromagnetic impact method.
The pull-in method is commonly used for single-layer concentric windings. It can be used in one go or in stages, achieving a slot fill factor of approximately 75%. The working principle of the wire unwinding machine is as follows: Guide fingers extend into the inner circle of the iron core, effectively extending the core slot opening axially. Each guide finger is positioned directly opposite a tooth, and the number of guide fingers equals the number of teeth. The coil is pre-attached to the guide fingers. As the pusher advances, the coil edge is pulled into the slot along the guide finger's groove edge, while simultaneously, the teeth on the pusher press all the remaining wire near the slot opening into the slot. The gap between the guide finger's groove edge should be a multiple of the wire diameter to prevent the wire from getting stuck when entering the slot. The slot die is pushed into the slot following the coil edge, pressing the wire already in the slot opening tightly. The coil end slides out of the guide fingers when the pusher advances to its stroke, maintaining a neat alignment of the ends.
The electromagnetic impact method utilizes the discharge of a capacitor to generate an electrical pulse, which in turn produces a strong current and electromagnetic impact force within the coil, pushing the coil into the stator or rotor slot. The flared end of the coil is formed by inertia. Due to the large electromagnetic force, the wire deforms under pressure after entering the slot, and the coil edges are tightly compressed within the slot, achieving a slot fill factor of over 80%.
In the electromagnetic impact method for coil embedding, the coil to be embedded is first placed into the groove of the coil pusher. The pusher is positioned inside the stator core, with the groove aligned with the stator slot opening to form a channel guiding the wire into the slot. A non-magnetic short-circuit device (i.e., a short-circuit ring, made of copper or aluminum) is fixed to the lower end of the pusher. When the capacitor bank discharges and a pulse current is applied to the coil to be embedded, magnetic flux is generated in the pusher core. The short-circuit device induces strong eddy currents and magnetic flux. The two magnetic fluxes repel each other and generate a repulsive force, pushing the coil into the stator core slot.
Enterprises will experience varying degrees of break-in period during the implementation of mechanized assembly. If the initial handling is not done properly, the failure rate will be relatively high after it is put into use. Compared with purely manual operation, human factors are eliminated, and the equipment cannot objectively perceive some unsuitability of the process. It should be noted that mechanized production is more suitable for mass production and is not suitable for production with relatively varied specifications.
