TWO-STAGE INSERT-MOLDED PRODUCT AND MANUFACTURE THEREOF

PURPOSE:To prevent local separation and poor weld from developing on the weld surface between a primary molding part and a secondary molding parts and consequently make it possible to bring the two molding parts into strong and close contact with each other by a method wherein at least either one of an inversed tapered notch and a fine groove is formed on the contact surface between the primary molding part and the secondary molding part and also splines are formed on the contact surface. CONSTITUTION:A continuous annular notch 8 is provided at the outer periphery of the out side end face 6a of a primary molding part 6 and a continuous annular fine groove 9 is provided inside the notch 8. The faces along the axis line of the notch 8 and of the fine groove 8 are formed in the inversed tapered shapes at an angle of 2-3 deg. toward an shaft hole 5. Further, a plurality of notches 10 are provided on the inner periphery of the out side end face be in the peripheral direction at fixed space intervals. A gap 11 is provided nearly along the total length of the shaft hole 5 so as to form a secondary molding part 7 between the primary molding part 6 and the shaft hole 5. A plurality of splines 12, which are parallel to the shaft center line, are provided on the inner peripheral surface of the primary molding part 6 in the peripheral direction at predetermined space intervals. Furthermore, a continuous annular kerf groove 13 is provided on a peripheral surface contacting the shaft hole 5 at the other end side end face 6d of the primary molding part 6. After the molding of the primary molding part 6, resin is injected in a cavity part for the second stage insert molding so as to form the secondary molding part 7 by filling the cavity part with resin.