Injection assembly for injection moulding machines for plastics material

An injection assembly (1) for injection moulding machines for plastics materials, comprising:

• a fixed frame (10, 21),
• a plastication cylinder (2) integral with said fixed frame,
• a plastication screw (5) acting inside said plastication cylinder (2), said plastication screw making a translational forward movement during the stage of injection of the plastics material inside a mould cavity and a rotatory movement around its own axis and a rotatory-translational movement of rotation around its own axis and retraction during the plastication stage of the plastics material, and
• drive means able to confer said translational, rotatory and rotatory-translational movements upon said plastication screw (5),
• characterized in that said drive means comprise:
• a movable plate (23) integral in translation with said plastication screw (5) and slidably mounted on said fixed frame,
• drive means for translation of said movable plate (23) comprising at least two drive screws (30), integral with said fixed frame (21), and engaging respectively in at least two lead screws or nuts (40) rotatably mounted on said movable plate (23), and drive means for the lead screws able to give said lead screws (40) a rotatory movement and comprising a crown gear (50) having external toothing which meshes with the external toothing of said lead screws (40), so as to simultaneously drive all the lead screws (40);
• said drive means of the plastication screw comprising a main motor (Mp;
• Mp′) comprising a drive shaft (70, 70′) connected, through connection means, to said plastication screw (5) and said crown gear (50) so that rotation of the drive shaft in one direction causes rotation of the plastication screw (5) and rotation of the drive shaft in the opposite direction causes rotation of the crown gear (50).

An injection assembly (1) for injection moulding machines for plastics materials, comprising:

• a fixed frame (10, 21),
• a plastication cylinder (2) integral with said fixed frame,
• a plastication screw (5) acting inside said plastication cylinder (2), said plastication screw making a translational forward movement during the stage of injection of the plastics material inside a mould cavity and a rotatory movement around its own axis and a rotatory-translational movement of rotation around its own axis and retraction during the plastication stage of the plastics material, and
• drive means able to confer said translational, rotatory and rotatory-translational movements upon said plastication screw (5),
• characterized in that said drive means comprise:
• a movable plate (23) integral in translation with said plastication screw (5) and slidably mounted on said fixed frame,
• drive means for translation of said movable plate (23) comprising at least two drive screws (30), integral with said fixed frame (21), and engaging respectively in at least two lead screws or nuts (40) rotatably mounted on said movable plate (23), and drive means for the lead screws able to give said lead screws (40) a rotatory movement and comprising a crown gear (50) having external toothing which meshes with the external toothing of said lead screws (40), so as to simultaneously drive all the lead screws (40);
• drive means for rotation of said plastication screw (5) comprising two independent motorizations (M1, M2) acting respectively on the plastication screw to set it in rotation and on the crown gear (50) to allow translation of said movable plate (23);
• said fixed frame comprising a base (10) comprising linear guides (20) on which said movable plate (23) can slide, and a fixed plate (21) substantially transverse to said base (10) integrally supporting said plastication cylinder (2);
• and
• said fixed plate (21) and said movable plate (23) being substantially square and the drive means of said movable plate (23) comprising four drive screws (30) mounted integrally near the four corners of said fixed plate (21) and engaging in four respective lead screws (40) rotatably mounted near the four corners of said movable plate (23).