Method to mold round polyurethane rollers free of injection gates, parting lines and bubbles

A method of manufacturing a electrophotographic developer roller in a cylindrical portion of a tube, comprising:

• defining a cylindrical cavity in the tube with a top end plug and a bottom end plug spaced by a shaft;
• injecting a pre-cured urethane mixture into the cylindrical cavity through an injection gate;
• before said urethane mixture is cured repositioning top and bottom end plugs to separate the cylindrical cavity from the injection gate;
• allowing the urethane mixture to cure;
• and
• removing the top and bottom end plugs and the roller comprised of the cured urethane mixture and shaft.

A method of manufacturing a electrophotographic developer roller in a cylindrical portion of a tube, comprising:

• vertically positioning the tube;
• defining a cylindrical cavity in the tube with a top end plug and a bottom end plug spaced by a shaft;
• providing an annular cavity between the top end plug and the tube;
• injecting a pre-cured urethane mixture into the cylindrical cavity of a predetermined amount to fill the cylindrical cavity and a portion of the annular cavity;
• allowing the urethane mixture to cure and to draw in urethane mixture from the annular cavity to compensate for shrinkage;
• and
• removing the top and bottom end plugs and the roller comprised of the cured urethane mixture and shaft.

A device for molding rollers, comprising:

• a tube having a cylindrical portion;
• a first end plug sized to slidingly seal a first section of the tube;
• a second end plug sized to slidingly seal a second section of the tube;
• an injection gate proximate the second end plug;
• and
• a roller shaft centered in the cylindrical portion and removably received on each end by the first and second end plugs;
• wherein the assembled first end plug, second end plug, and shaft are slidable between a first position and second position with the tube to selectably couple the injection gate to the cylindrical portion of the tube.