Abstract: The present invention is concerned with a method of and a machine for the production by injection welding of articles of large size and/or complex structures having, at least locally, composite portions formed by the introduction of one of at least two materials of different compositions inside the other, said method comprising the steps of: injecting a first material into at least two different zones of a mould and then injecting a second material into the first material at said zones, the second material pushing the first material against the walls of the mould; and creating in the junction plane of the masses of the first material, a leakage of a pre-determined quantity of said first material, so as to permit the joining and mixing of the two masses of the second material at the level of the junction of the masses of the first material.

Abstract: The invention relates to a method for the manufacture by injection molding of articles composed of a plurality of layers of at least three distinct materials coated one over the other, the method comprising the steps of successive injection of a measured quantity of a first material adapted to form the skin of the article, a measured quantity of a second material to form the intermediate layer, and a measured quantity of a third material to form the body of the article, the materials being introduced into the mold coaxially so as to give a uniform distribution. The invention is especially applicable to the production of articles in which the external and internal materials are joined together by an intermediate material.

Abstract: The present invention is concerned with a machine for the production by injection welding of articles of large size and/or complex structures having, at least locally, composite portions formed by the introduction of one of at least two materials of different compositions inside the other, the apparatus including a mould having fixed and movable portions, at least two separate systems for supplying materials to be injected into the said mould, and at least two distribution valves for these materials, one of the valves being of the multi-way type so as to cause a common discharge channel for material into the mould to communicate with either or both of the separate material-supply systems.

Abstract: The invention relates to a method of and apparatus for the manufacture of articles, for example of imitation tortoise-shell, by injection moulding, in which local masses of at least one material are embedded from place to place in at least one other material, said materials being respectively each delivered by a separate plastification unit and terminating at an injection mould through a single common discharge channel, said method comprising the steps of delivering said materials in continuous and simultaneous streams by means of said plastification units; breaking-up each continuous stream of material into a series of measured quantities of said material, the quantities of one of the streams being intercalated with the quantities of the other stream; and successively injecting each measured quantity into said mould while causing them to penetrate into each other. The injection of the materials into the mould is preferably effected transversely to the plane of movement of the materials.

Abstract: The invention relates to apparatus for the manufacture by injection molding of articles composed of a plurality of layers of at least three distinct materials coated one over the other, in which there is injected a measured quantity of a first material adapted to form the skin of the article, a measured quantity of a second material to form the intermediate layer, and a measured quantity of a third material to form the body of the article, the materials being introduced into the mold coaxially so as to give a uniform distribution. The injection-molding apparatus includes an injection nozzle having a single discharge channel opening on the side of the mold and at least three coaxial chambers each connected to a separate supply circuit for each material to be injected. The invention is especially applicable to the production of articles in which the external and internal materials are joined together by an intermediate material.