The main load borne by the motor base during operation
(1) Gravity load, usually the self weight of the stator. In motors using end cap bearings, they also need to bear the weight of the rotor, while in suspended hydro generators, they need to bear the weight of the rotating parts of the unit, the upper frame, etc.
(2) Unilateral magnetic pulling force and radial force caused by thermal expansion of the iron core.
(3) In the case of internal pressing and round punching, certain parts of the machine base must withstand the axial rebound force of the iron core; For a suspended hydro generator, it must withstand axial water thrust.
(4) Torque. Including transient electromagnetic torque during sudden load changes and generator short circuits.
Among the above loads, torque is the most important. In addition, the base of a general motor will also be subjected to clamping force, cutting force, lifting force, etc. during processing, transportation, and installation; For motors that require sealing (such as hydrogen cooled steam turbine generators or explosion-proof motors), the machine base must also withstand the test pressure. When using end cap bearings and belt (or gear transmission mechanisms) for transmission, the machine base and its feet will also be subjected to the tension of the belt (or the force of the gear transmission mechanism). Therefore, when designing a machine base, the mechanical calculation of the machine base usually includes the calculation of its stiffness, strength, and natural vibration frequency. For a half machine base, the strength calculation of the joint plate bolts needs to be carried out, and for a welded machine base, the stress calculation of the bottom plate weld needs to be carried out, mainly the stiffness calculation of the machine base.
