Screw position adjustment device for injection molding machine

A screw position adjusting device for an injection molding machine that comprises a material supply cylinder having a first chamber, an injection cylinder having a second chamber, a connection part having a communicating passage that communicates the first chamber with the second chamber, a screw rotating in the material supply cylinder and plasticizing or mixing a material in a retracted position that is away from the communicating passage, an injection shaft injecting the material in the injection cylinder, a rotating device rotating the screw, and a reciprocating device reciprocating the screw in an axial direction between an advanced position where the screw contacts the connection part to close the communicating passage and the retracted position, the screw position adjusting device adjusting the retracted position in the injection molding machine and comprising:

• a thread having a through-hole that extends in the axial direction and being immovable with respect to the material supply cylinder;
• a position adjustment nut screwed to an outer peripheral surface of the thread for determining the retracted position;
• a fastener fixing a position of the position adjustment nut;
• and
• a casing having an opening for access to the position adjustment nut and the fastener and covering the position adjustment nut and the fastener.