| 摘要 |
A method for manufacturing commutators for electric motors wherein a hollow cylindrical body is provided having longitudinal grooves and ridges on its inner surface. The circumferential widths of the inner grooves are initially larger than the desired ultimate widths. A plurality of longitudinal outer grooves are formed on the outer surface of the cylindrical body, the outer grooves each having a bottom wall radially spaced from the longitudinal axis a distance substantially equal to the radial spacing of the bottom walls of the inner groove from the longitudinal axis. The outer grooves are staggered circumferentially relative to the inner grooves and the spaces therebetween define a plurality of yieldable cross-pieces. Radially inwardly directed shrinking forces are applied uniformly to the outer surface of the cylindrical member to break the yieldable cross-pieces and thereby decrease the widths of the inner grooves, the decrease thereof being equal to the widths of the outer grooves. |
