Electromagnetic pipe expanding inductor and method for manufacturing the same

Abstract

Provided is an electromagnetic pipe expanding inductor in which the formation of voids during resin impregnation is suppressed, and electromagnetic reaction forces acting on the conductor periphery and on the interface between the shaft portion and the center-side fiber layer is diminished, and thereby durability is improved and the life of the inductor is prolonged. A glass cloth tape () capable of being impregnated with resin is wound around the peripheral surface of a shaft portion of a bobbin () to a predetermined thickness, further, a conductor strand () coated with a glass cloth tape () is wound spirally in the axial direction of the bobbin () to form a coil. Further, a glass cloth () is wound around the outside of the glass cloth tape () to a predetermined thickness and thereafter the glass cloth tapes () and the glass cloth () are impregnated with resin to unite them. A center-side resin-impregnated layer formed by the glass cloth tape 3 impregnated with resin is lower in the modulus of longitudinal elasticity than the shaft portion. Given that the inductor radius is r, the thickness, t, of the center-side resin-impregnated layer is 0.025r to 0.25r.