A co-injection nozzle for an injection moulding device for producing multi-layered injection-moulded products. The nozzle includes: a central bore; a valve needle for opening and closing a nozzle opening; an annular inner melt channel for the first melt; an annular central melt channel for a second melt; and an annular outer melt channel for the first melt, the inner, central and outer melt channels being fluidically combined in the nozzle tip to form a concentrically-layered melt stream. The nozzle further includes a nozzle body and a melt runner insert having the central bore of the nozzle. The melt runner insert has a circular cylindrical section, by which the insert is held in a central bore of the nozzle body. At least one distribution channel for the first melt and at least one distribution channel for the second melt are formed in the outer surface of the circular cylindrical section, with the distribution channels running substantially in the axial direction.

A co-injection nozzle for an injection moulding device for producing multi-layered injection-moulded products. The nozzle includes: a central bore; a valve needle for opening and closing a nozzle opening; an annular inner melt channel for the first melt; an annular central melt channel for a second melt; and an annular outer melt channel for the first melt, the inner, central and outer melt channels being fluidically combined in the nozzle tip to form a concentrically-layered melt stream. The nozzle further includes a nozzle body and a melt runner insert having the central bore of the nozzle. The melt runner insert has a circular cylindrical section, by which the insert is held in a central bore of the nozzle body. At least one distribution channel for the first melt and at least one distribution channel for the second melt are formed in the outer surface of the circular cylindrical section, with the distribution channels running substantially in the axial direction.

A resin molding method includes a first molding step of molding a first molded part and a second molded part in a mold and a second molding step of joining the first molded part and the second molded part. In the first molding step, the second molded part is formed by injecting resin into an area where a first core movable in the first direction and a second core movable in a second direction are engaged. In the second molding step, the second molded part is joined to the first molded part by injecting the resin while the first core is in contact with the second molded part and the second core is removed from the second molded part. Areas where the first core and the second core are located in the first molding step become hollow areas connected to each other and part of ends of the first core in the first direction is not in contact with the second core.

A resin molding method includes a first molding step of molding a first molded part and a second molded part in a mold and a second molding step of joining the first molded part and the second molded part. In the first molding step, the second molded part is formed by injecting resin into an area where a first core movable in the first direction and a second core movable in a second direction are engaged. In the second molding step, the second molded part is joined to the first molded part by injecting the resin while the first core is in contact with the second molded part and the second core is removed from the second molded part. Areas where the first core and the second core are located in the first molding step become hollow areas connected to each other and part of ends of the first core in the first direction is not in contact with the second core.