Retractable undercut core pull

A mold for creating a double wall blow molded article, the mold having a cavity side and a core side, the core side of said mold comprising:

• a mold surface against which the article bears during molding;
• at least one core pull disposed within the core side of said mold, said at least one core pull comprising a piston having a protuberance, the piston being moveable, at least partially in response to fluid pressure, between an extended position in which the protuberance protrudes beyond the mold surface, and a retracted position in which the protuberance does not substantially protrude beyond the mold surface, the piston being moveable generally perpendicular to a mold open-close plane of said mold;
• at least one ejector pin disposed within the core side of said mold, said at least one ejector pin comprising an end moveable between an extended position in which the end protrudes beyond the mold surface, and a retracted position in which the end does not substantially protrude beyond the mold surface, the end being moveable generally parallel to the mold open-close plane of said mold;
• wherein the protuberance of said at least one core pull is in the extended position thereof and the end of said at least one ejector pin is in the retracted position thereof during a part retaining portion of a mold cycle;
• and
• wherein the protuberance of said at least one core pull is in the retracted position thereof and the end of said at least one ejector pin is in the extended position thereof during a part ejecting portion of the mold cycle.

A mold for creating a double wall blow molded article, the mold having a cavity side and a core side, the core side of said mold comprising:

• a mold surface against which the article bears during molding;
• at least one core pull disposed within the core side of said mold, said at least one core pull comprising a piston having a protuberance, the piston being moveable, at least partially in response to fluid pressure, between an extended position in which the protuberance protrudes beyond the mold surface, and a retracted position in which the protuberance does not substantially protrude beyond the mold surface, the piston being moveable generally perpendicular to a mold open-close plane of said mold;
• wherein the protuberance of said at least one core pull is in the extended position thereof during a part retaining portion of a mold cycle;
• and
• wherein the protuberance of said at least one core pull is in the retracted position thereof during a part ejecting portion of the mold cycle.

A method of creating an article comprising the steps of:

• providing a mold having a cavity side and a core side, the core side having a mold surface against which the article bears during molding;
• causing a protuberance of at least one core pull to protrude beyond the mold surface;
• causing an end of at least one ejector pin to be retracted such that it does not substantially protrude beyond the mold surface;
• molding the article within the mold;
• opening the mold;
• retracting the protuberance of the at least one core pull such that it does not substantially protrude beyond the mold surface;
• and
• ejecting the article from the core side of the mold by causing the end of the at least one ejector pin to protrude beyond the mold surface.