Material extrusion mechanism and molding machine

A material extrusion mechanism comprising:

• a cylinder including a supply port to which a material is supplied, the cylinder being provided in a vertical direction;
• a screw including a spiral flight section and configured to rotate centering on a rotation axis extending in the vertical direction on an inside of the cylinder;
• a first cooling section provided to surround a part of the screw;
• a heating section provided to surround a part of the screw below the first cooling section;
• and
• at least one nozzle configured to discharge the material plasticized on the inside of the cylinder, wherein
• at least a part of the supply port overlaps the first cooling section in a horizontal direction,
• the screw includes:
• a first portion in which an outer diameter of the flight section is a first diameter;
• and
• a second portion in which the outer diameter of the flight section is a second diameter smaller than the first diameter,
• the first portion overlaps the heating section in the horizontal direction, and
• the second portion overlaps the first cooling section in the horizontal direction.