| 摘要 |
A core main body comprises fi rst core segments havi ng a small circumferential width and having both circumferential end surfaces as first butting surfaces, and second core segments having a large circumferential width and having both circumferential end surfaces as second butting surfaces, the core main body is formed into an annular shape by butting the circumferentially adjacent first and second butting surfaces against each other. The first butting surface comprises a parallel surface portion being parallel with a center pl ane in the ci rcumferenti al width of the fi rst core segment connected to radially outside of an outwardly inclined surface portion inclined so that the ci rcumferenti al width increases toward the inside in a radial direction. |
