Patent ID: 8928445
Filing Date: 2015-01-06
Classification: B21D,H01F,Y10T

Abstract:
1. An electromagnetic pipe expanding inductor comprising: a shaft portion; a center-side resin-impregnated layer different in strength characteristics from said shaft portion, said center-side resin-impregnated layer being formed by impregnating insulating resin into a resin-impregnatable fiber layer coated on a periphery of said shaft portion and then hardening said insulating resin, wherein said center-side resin-impregnated layer is wound spirally at least partly overlapping to a predetermined thickness, the predetermined thickness being based on a number of turns of the center-side resin-impregnated layer; a coil formed by winding a conductor around a peripheral surface of said center-side resin-impregnated layer, said conductor being completely coated with a resin-impregnatable fiber layer impregnated with insulating resin, said insulating resin being hardened after the impregnation, wherein the conductor has a hollow portion defined therein for circulating refrigerant therethrough; and an outer resin-impregnated layer formed by impregnating a resin-impregnatable fiber layer coated on an outer periphery of said coil with insulating resin and hardening said insulating resin; wherein a radius of the electromagnetic pipe expanding inductor is 35 mm or smaller, and when a modulus of longitudinal elasticity of said shaft portion and that of said center-side resin-impregnated layer are E1 and E2, respectively, said shaft portion is formed of a material having an E1/E2 ratio of 1.9 or more.