Fastening structure

A fastener for detachably fastening first and second workpieces together, said first workpiece having a through aperture of predetermined shape, said second workpiece having a through aperture of predetermined shape including a first small diameter portion having first opposed edges spaced apart a first predetermined distance and a second annularly displaced portion having second opposed edges spaced apart a second relatively larger predetermined distance, said fastener comprising:

• a base, a first catch portion integral with and extending outwardly from a first side of said base, said first catch portion being insertable into and engageable within said first workpiece aperture for securing the fastener with respect to the first workpiece;
• a second catch portion integral with and extending outwardly from said base oppositely from said first catch portion, said second catch portion including an axially twistable resilient stem twistable in rotation relative to and independently of the base and the first catch portion remaining in engagement with the first workpiece from a normal relaxed position to a twisted rotated position reactively urged to return to the normal position and a pair of resilient catch members on the stem in distal relation to the base and normally assuming an outward position, said catch members including workpiece engageable surfaces normally spaced apart a distance greater than said first predetermined distance and less than said second predetermined distance, said catch members being resiliently collapsible upon axial insertion between said first opposed edges defining the first predetermined distance for enabling said surfaces to be snapped through said second workpiece aperture for engaging said first opposed edges and securing the second workpiece with respect to the fastener;
• and means integral with an outer end of said stem for enabling the stem to be twisted from its normal position relative to the base to its rotated position with bodily similar rotation of the catch members with the outer end of the stem relative to the base for angularly spacing said catch members in their normal outward positions for disengagement from said first opposed edges by registry thereof between the second opposed edges and for withdrawal from the second workpiece aperture between said second opposed edges whereby, upon disengagement of the fastener, the stem with the catch members is reactively rotated to the normal positions thereof in readiness for repeated snap reengagement of the catch members with the first opposed edges to assemble the fastener with the disengaged workpiece.