A polygonal coil having a substantially square shape is manufactured by winding a conductive wire in the diameter direction of the core on the core in an overlapping manner by the use of a winding jig in which a first collar portion and a second collar portion are disposed at both ends of a core so as...http://www.google.com/patents/US7475843?utm_source=gb-gplus-sharePatent US7475843 - Winding jig, polygonal coil, and method of manufacturing polygonal coil
