US Patent 7725994 Buckle, injection molding die and injection molding method

A plug (20) has a guide bar (24) to be inserter in a socket (30). The guide bar (24) has a to-be-held section (241) at a tip end thereof, a dent (244) at a middle portion thereof, and a sub to-be-held section (242) at a base end thereof. When making an engagement, the plug (20) is slanted relative to the socket (30), so that the guide bar (24) contacts contact points (P1), P2). When the plug has been inserted into a depth end of the socket, the to-be-held section (241) and the sub to-be-held section (242) are held by a holding section (342) and a sub holding section (343) of the socket (30), thereby stabilizing engagement posture.