Screw linkage structure for use in an injection molding machine

A screw linkage structure in an injection molding machine, comprising:

• a screw having at its base a spline portion;
• a spline bush receiving said spline portion of said screw;
• a screw sleeve having a front surface to which said spline bush is fixed and at least one side;
• and
• a retainer serving to prevent said screw from being disengaged from said spline bush, said retainer having a leading edge;
• wherein
• said spline portion formed on said screw based includes an annular groove,
• said spline bush includes a through-hole at a position corresponding to said annular groove of said screw base,
• said retainer is inserted into said through-hole of said spline bush until the leading edge of said retainer reaches said annular groove of said screw base,
• said retainer is provided with a fastener means for fastening said retainer, whose leading edge is engaged with said annular groove, to one of the at least one side of said screw sleeve,
• said fastener means attached to said retainer comprises a plunger, a pin, and a spring for biasing said pin toward the direction in which said pin protrudes from said plunger, and
• said screw sleeve includes at the front surface, an engagement holder for receiving said pin at a position corresponding to that when the leading edge of said retainer has reached said annular groove of said screw base.