SQUIRRELLCAGE ROTOR CORE AND MANUFACTURE THEREOF

摘要

PURPOSE:To greatly reduce a stray-load loss and provide an efficient squirrel-cage rotor core, by making the thickness of a coated insulating film on the inside surface of a bar casting groove large on the upper portion of the groove but small on its lower portion. CONSTITUTION:A core 5 is dipped in a solution of a heat-resisting insulating paint such as silicon resin so that the paint is coated on the entire surface of each groove 1. After the core is picked out of the solution, the core is put on rollers 10, 11. The driving roller 10 is slowly rotated in a direction A by a stepless transmission or the like so that the core 5 is rotated in a direction B and the coated film 6 on the surface of the groove 1 is moved toward the peripheral surface of the core 5 by the centrifugal force. The coated film is then dried by heating so that the thickness of the coated film is large and uniform at 8 on the upper portion 1a of each groove 1 but small at 9 on the lower portion 1b of the groove. This results in greatly reducing a stray-load loss and providing an efficient squirrel-cage rotor core.