Method for injection-molding a propeller fan

A method for injection-molding a plastics propeller fan by using a fixed-side mold section and movable-side mold section, comprising the steps of:

• providing a movable core at an area corresponding to a thicker portion of a blade section of the propeller fan;
• after a predetermined amount of plastics material has been injected into a blade space of a mold cavity defined by the fixed-side mold section, movable-side mold section and movable core and conforming to the propeller fan, pushing out the movable core into the mold cavity;
• and
• thereafter, bringing the movable core back to a normal position conforming to a mold shape defining the blade space and forming a propeller fan;
• wherein the molding is performed by abutting the movable core only against a thicker portion corresponding to a central area of the blade without abutting the movable core against a blade peripheral edge portion and blade base portion of the propeller fan.

A method for projection molding a plastics propeller fan by using a fixed-side mold section and movable-side mold section, comprising the steps of:

• providing a movable core at an area corresponding to a thicker portion of a blade section of the propeller fan;
• after the movable core has been pushed out toward an inside of a blade space of a mold cavity defined by the fixed-side mold section, movable-side mold section and movable core and conforming to the propeller fan, pressure-injecting a plastics material into the mold cavity to allow the material to be filled in the mold cavity;
• and
• thereafter, bringing the movable core back to a normal position conforming to a mold shape defining the blade space and forming a propeller fan.

A method for projection molding a plastics propeller fan by using a fixed-side mold section and movable-side mold section, comprising the steps of:

• providing a movable core at an area corresponding to a thicker portion of a blade section of the propeller fan;
• after the movable core has been pushed out toward an inside of a blade space of a mold cavity defined by the fixed-side mold section, movable-side mold section and movable core and conforming to the propeller fan, pressure-injecting a plastics material into the mold cavity to allow the material to be filled in the mold cavity;
• and
• thereafter, bringing the movable core back to a normal position conforming to a mold shape defining the blade space and forming a propeller fan;
• wherein the molding is performed by abutting the movable core only against a thicker section corresponding to a central area of the blade core without abutting a blade peripheral edge portion and blade base portion of the propeller fan.