Abstract: A method of producing a polymer insulator and an end processing apparatus utilized for the method. The insulator has a core, an overcoat member arranged on the core, and a fitting member for securing the core at its both ends, wherein the core and the fitting member are secured under pressure at both ends of the core by contacting a ring-shaped protrusion portion arranged at both ends of the overcoat member to an open inner end of the fitting member. The method includes the steps of: forming the overcoat member on the core; forming the ring-shaped protrusion portion integrally with the overcoat member by processing an end portion of the overcoat member, and securing the fitting member.

Abstract: A method of producing a polymer insulator having a core, an overcoat member arranged on the core, and a fitting member for securing the core at its both ends, wherein the core and the fitting member are secured under pressure at both ends of the core by contacting a ring-shaped protrusion portion arranged at both ends of the overcoat member to an open inner end of the fitting member, includes the steps of: forming the overcoat member on the core; forming the ring-shaped protrusion portion integrally with the overcoat member by processing an end portion of the overcoat member; and securing the fitting member.

Abstract: A method of forming an overcoat member of a polymer insulator having a core member. The overcoat member is made of a sheath portion arranged around the core member and includes a plurality of sheds. The overcoat member is formed by using a metal mold, and during a forming operation, a spacer for maintaining a thickness of the sheath portion is arranged to a portion of the metal mold corresponding to the sheath portion.

Abstract: A process for producing, by compression molding, an insulator having a core and a housing consisting of a sheath portion and at least one shade portion around the sheath portion, including the steps of: (A) preliminarily forming a rubbery layer around an outer periphery of the core to obtain a preliminarily molded body by extrusion molding, (B) placing the preliminarily molded body between at least two mold units of a mold; (C) forming a compressed molding by compression molding said preliminarily molded body in a given shape inside a cavity defined by the at least two mold units; and (D) curing the resulting molding. An apparatus is also disclosed for producing such an insulator by compression molding, which apparatus includes (A) a preliminary molding unit, (B) a molding unit form forming a compressed molding from the preliminarily molded body in a given shape by using a mold, and (C) a heater for curing the rubber in the rubber layer.