THREEEPHASE INSULATING SPACER

摘要

PURPOSE:To obtain a stable shape of spacer as well as prevent cracking by reducing resistance to shrinkage by providing a coupling portion relatively to cast form in a flat region surrounded with a boss portion having a great shrinkability and O- ring groove. CONSTITUTION:The flat portion 16 between the boss portion 15 and the O-ring groove-forming projection 14 is given the easy projection 17 by which a resistance to interrupt shrinkage toward radial direction is shared and also a resistance to burden the O-ring groove-forming projection 14 is relieved. Thus, it is possible to relieve the O-ring groove portion of its resistance to shrinkage during formation and thereby to prevent the development of cracks, assuring a high quality three-phase spacer of a stable shape.