Injection co-molding and assembling method and apparatus for articles made of plastic material having parts connectable by hinging during a demolding step

An injection molding apparatus adapted for co-molding and assembling a first part and a second part of a molded article in plastic material inside a mold, in which the first and second parts of the molded article are hingedly connected by hinge pins and annular hinge elements, the molding apparatus comprising:

• first and second mold members defining, between them, first and second molding cavities for said first and second parts of the molding apparatus comprising:
• the first mold member having a central core axially extending and conforming to said first molding cavity;
• a demolding device for the molded article, comprising a demolding ring coaxially and movably arranged in respect to the central core of the first mold member;
• in which the mold is provided with auxiliary molding assemblies each comprising coaxially arranged rod and tubular pin members slidably supported in a radial direction by the demolding ring;
• said rod and tubular pin assemblies being conformed to provide axially aligned molding cavities for the hinge pins and the annular hinge elements of the auxiliary molding assemblies;
• and
• cam control means on the first mold member, operatively connected to the rod and tubular pin members of the auxiliary molding assemblies, the cam control means being conformed and arranged to selectively control forward and backward movements of the rod and tubular pin members during the assembling of the first and second parts of the molded article, to engage the annular hinge member and the hinge pin by the movement of the demolding ring at the opening of the mold.