Fastener for fastening plates together

A fastener, comprising:

• a female body to be inserted through aligned first and second holes formed within overlapped first and second plates to be fastened together;
• and
• a male body for causing flaring of said female body,
• said female body having a head portion for engaging a plate surface portion surrounding said first one of said holes defined within said first plate, a plurality of circumferentially spaced-apart leg portions depending from said head portion and each having an inner projection projecting from a lower free end portion and an axially central male body insertion hole penetrating said head portion and extending axially centrally between said leg portions,
• said male body having a pin-like portion having sufficient length so as to penetrate the entire length of said insertion hole, said pin-like portion having an axially intermediate large-diameter portion having a diameter not greater than the diameter of said insertion hole of said female body and first and second small-diameter portions separated by means of said large-diameter portion, said male body further having a plurality of elastic engagement pieces extending obliquely upwardly and outwardly from a lower end portion of said pin-like portion,
• said fastener being capable of changing its state between a first state in which said male body is temporarily coupled to said female body by inserting said male body into said insertion hole of said female body such that said inner projections of said leg portions of said female body abut said first small-diameter portion of said male body and said elastic engagement pieces project outwardly through gaps defined between adjacent leg portions of said female body, a second state in which said leg portions of said female body are flared outwardly as a result of abutment of said inner projections of said leg portions of said female body with said large-diameter portion of said male body, and a third state in which said leg portions of said female body are brought closer to one another as a result of said inner projections of said leg portions of said female body being brought into abutment with said second small-diameter portion of said male body,
• said female and male bodies being provided with respective stopper means which engage each other in said first state so as to prevent any change of said fastener from said first state to said second state,
• one of said female and male bodies being further provided with releasing means for releasing said engagement between said stopper means when said leg portions of said female body are inserted through said second one of said holes defined within said second plate to be fastened to said first plate.