Buckle, injection molding die and injection molding method

A buckle, comprising:

• a plug;
• a socket, the plug and the socket being engaged in a predetermined engagement direction;
• and
• a lock mechanism for maintaining the plug and the socket in engagement in a releasable manner, wherein
• the plug and the socket have:
• a first direction intersecting the engagement direction;
• and a second direction intersecting both of the engagement direction and the first direction,
• the socket has:
• an insertion opening;
• and a cavity extending from the insertion opening toward inside of the socket,
• the plug has a lock arm,
• the lock mechanism has:
• an arm-side lock member formed on the lock arm;
• and a socket-side lock member formed on the socket,
• at least one of the arm-side lock member and the socket-side lock member is a slant surface contactable with the other,
• the slant surface has:
• a back side in the engagement direction continuous with an outer surface of the socket;
• and a front side in the engagement direction positioned inside the socket, the slant surface being slanted relative to any of the engagement direction, the first direction and the second direction.

A buckle, comprising:

• a plug;
• and
• a socket, the plug and the socket being engageable with and releasable from each other, wherein
• the plug has a guide bar to be inserted in the socket, and
• the guide bar has:
• an abutting section to be in slidable contact with the socket;
• and a non-abutting section not to be in slidable contact with the socket.

An injection molding die, comprising:

• a fixed die and a movable die that form a molding cavity when the fixed die and the movable die are closed;
• a slide core provided in the cavity in an advanceable and retractable manner, the slide core forming an undercut on a molding article molded in the cavity;
• and
• a displacement mechanism for displacing the slide core in a depth direction of the undercut.

An injection molding method, comprising the steps of:

• providing an injection molding die having a fixed die and a movable die that form a molding cavity when the fixed die and the movable die are closed;
• a slide core provided in the cavity in an advanceable and retractable manner, the slide core forming an undercut on a molding article molded in the cavity;
• and a displacement mechanism for displacing the slide core in a depth direction of the undercut;
• closing the fixed die and the movable die to form the molding cavity;
• injecting a molten resin into the molding cavity;
• opening the fixed die and the movable die after the molten resin is solidified;
• and
• ejecting the molding article by advancing the slide core and displacing the slide core in the depth direction of the undercut by the displacement mechanism.