Abstract: A plasticizing and injecting device for a plastics injection molding machine includes an axially fixed and rotationally driven plasticizing screw, and an injection plunger movable forwards and backwards inside the plasticizing screw by a linear drive and including, at its front end, a non-return valve. An injection cylinder is provided anteriorly of the plasticizing cylinder. The non-return valve can be moved by the injection cylinder forwards and backwards inside the injection cylinder between a rear position at the beginning of the injection process and a front position after completion of the injection process. In addition, a melt chamber is formed between the front end of the plasticizing screw and the non-return valve, and forms, during the injection process and during the holding pressure phase, an annular gap between the injection plunger and the injection cylinder for receiving plastic melt as the plasticizing screw continues to rotate during injection.

Abstract: The invention relates to a hydraulic device for the back and forth movement and locking of a machine part, in particular for the opening, closing and locking of an injection molding tool. The hydraulic device comprises a cylinder (1), in which a first pressure space (6) is provided, a primary piston (2) with one or several piston rods (11) which may float in a pressure medium within the first pressure space (6) and furthermore an secondary piston (7) which may be axially displaced within the cylinder (1). The invention is characterized in that the auxiliary piston (7) comprises recesses (12), into which the piston rods (11) of the primary piston (2) can be moved and the opposing sides of the primary piston (2) and secondary piston (7) have surfaces (40, 41) which may be brought into contact. In a first movement phase (opening and closing) only the primary piston (2) is moved.

Abstract: The invention relates to a hydraulic device for the back and forth movement and locking of a machine part, in particular for the opening, closing and locking of an injection molding tool. The hydraulic device comprises a cylinder (1), in which a first pressure space (6) is provided, a primary piston (2) with one or several piston rods (11) which may float in a pressure medium within the first pressure space (6) and furthermore an secondary piston (7) which may be axially displaced within the cylinder (1). The invention is characterized in that the auxiliary piston (7) comprises recesses (12), into which the piston rods (11) of the primary piston (2) can be moved and the opposing sides of the primary piston (2) and secondary piston (7) have surfaces (40, 41) which may be brought into contact. In a first movement phase (opening and closing) only the primary piston (2) is moved.

Abstract: This clamping device (5) is of the type comprising a peg (6) which projects from the half-mold (2) and which is received in a recess (17) in the platen, and a clamping mechanism (5) including a transverse cylinder (9) and a wedge (8) deigned to interact with the peg in order to ensure the removable clamping of the half-mold. The clamping mechanism (5) comprises a bearing block (7) designed to be fixed at the entrance of the recess (17) and including, on the one hand, a passage (25) for the peg (6), and, on the other hand, an incline (24) for the bearing of the wedge (8), this incline being provided on that face of the block which points towards the recess in the platen. The peg (6) is axisymmetric with a widened head (14). The clamping device finds applicability in the injection-molding of plastics.

Abstract: A generally planar object 22 subject to dimensional variations is centrally held in a mold by a deformable suction ring 20, and inflatable seals 8, 9 are urged against its opposite peripheral surfaces to define a cavity 17 for the injection molding of a precisely dimensioned edge frame 23. The dimensions of the rigid mold halves 2, 3 and the elasticity of the ring and seals are such that a wide range of dimensional variations may be tolerated in the object, which may be a curved automobile glass panel, a printed circuit board, etc.

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 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.