New solutions in the maintenance of the asynchronous motors with integrated gear and single demountable bearing shield: Devices to extract and insert the ferromagnetic cores of the stator (case study)

Generally, asynchronous motors used in actuator systems (whether they are three-phase or single-phase motors) have two demountable bearing shields. This design allows easy access to the winding, on both sides of the stator, making the maintenance a relatively simple process. Another type of motor, with a special design, also exists. It has a single removable bearing shield, the other being made integral with the stator housing. Such a construction has a series of advantages: it allows for better alignment of the rotor shaft with the first gear of the reducer and the electrical brake, provides better sealing, increasing resistance to heavy operating conditions such as humidity, dust, gas, vibration etc. As a disadvantage, in case of winding failure, because the design doesn't allow for access to the winding at both ends of the stator as in normal motors, the replacement of the defective winding is not possible. The problem is, therefore, to find a method to extract the ferromagnetic stator core with its windings and, after a new winding is installed and after coating, to insert the stator back into the housing. This paper presents two novel constructive solutions: the first solution presents a device for extracting the ferromagnetic core from the housing, and the second describes a device for pressing the ferromagnetic core in its housing. These two devices have been designed to allow the repair of small power electric motors that have a single removable bearing shield (the other being made integral with the stator housing). Both devices are manually operated and are a specific element of the central screw driven by a handle. Extracting stator ferromagnetic core device is inserted in place of the rotor of motor to be repaired, stator core sitting on the bottom and extracting it from the housing. The device for pressing the ferromagnetic core in the housing exerts a force on the stator core at the top, while the housing is fixed. Both devices are subject to OSIM patents.