Ring-shaped insert molded article

Abstract

A molded article 1 is configured such that an insert 2 is made of a steel plate and includes a cylindrical part 2 A and an annular part 2 B, a plastic 4 is annular in shape so as to be joined to the annular part 2 B, inner diameter D 1 of the plastic 4 is larger than inner diameter D 2 of the annular part 2 B so that no burrs at a gate mark E protrude to the inner diameter side of the molded article 1 , the injection molding is conducted with a disc gate arranged on an inner peripheral surface F of the plastic 4 at a position separated from a surface of the annular part 2 B, and the gate mark E resides on the inner peripheral surface F of the plastic 4 at a position separated from the surface of the annular part 2 B.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . A ring-shaped insert molded article manufactured by injection molding in a state where a thermoset adhesive is applied to a joining surface of a ring-shaped insert to a plastic and then the insert and the plastic are placed in a metal mold, wherein
 the insert is made of a steel plate and includes a cylindrical part and an annular part extended radially inward from one end edge of the cylindrical part,   the plastic is cylindrical in shape so as to be joined to an outer peripheral surface of the cylindrical part of the insert and has a curve part over the annular part,   the injection molding is conducted with a disc gate arranged on an inner peripheral surface of the plastic at a position separated from a surface of the annular part, and   in the gate-cut state, a gate mark resides on the inner peripheral surface of the plastic at a position separated from the surface of the annular part so that no foreign matter resulting from gate cutting sticks to the surface and no shearing load is applied by gate cutting to the joining surface to prevent degradation of adhesive performance.   
     
     
         4 . The ring-shaped insert molded article according to  claim 3 , wherein
 the ring-shaped insert molded article is a radial magnetic encoder in which the ring-shaped insert is a support member and the plastic is a plastic magnet, and   the gate mark resides at a position separated 0.1 mm or more from the surface of the annular part.