Method and apparatus for manufacturing curved pipe

A curved pipe manufacturing apparatus comprising:

• a fixed die having a curved cavity with an entrance opening an an exit opening;
• a mandrel formed into a shape capable of being inserted into the curved cavity of the fixed die through the exit opening thereof and form a curved space corresponding to the shape of a curved pipe to be formed in the curved cavity;
• a presser rod for pressing a straight pipe into the curved space to form a curved pipe;
• an ejecting rod formed in a shape capable of being inserted into and removed from the entrance opening of the curved cavity to eject a curved pipe from the fixed die;
• a movable block having the mandrel and the ejecting rod concentrically mounted on opposite sides thereof, said movable block being supported on a rotary shaft which inserts the mandrel into and removes the mandrel from the exit opening of the curved cavity and inserts the ejecting rod into and removes the ejecting rod from the entrance opening of the curved cavity;
• and
• a controller means for controlling driving mechanisms to temporarily interrupt the advancing motion of the presser rod after a sensor has detected that the presser rod has advanced a predetermined distance, to slightly remove the mandrel from a curved portion of the work, to restart the advancing motion of the presser rod to further press the work into the curved space and, after the curved pipe has been formed completely, to turn the movable block for removing the mandrel from the exit opening of the curved cavity and to insert the ejecting rod into the entrance opening of the curved cavity for ejecting the formed pipe from the fixed die.