Zip-fastener

Claim 1

A slide fastener comprising pieces of fabric having attached thereto engageable and disengageable interlocking fastener elements, a slider for engaging and disengaging said fastener elements, comprising upper and lower cover plates in substantially parallel relation, said cover plates having opposed recesses in the adjacent surfaces for receiving said fastener elements slidably, said recesses having curvilinear sides diverging outwardly to form two guide channels at one end of said slider which longitudinally converge to a single guide channel at the opposite end of said slider, said cover plates having two sets of generally rectilinear sides each set extending outwardly from the longitudinal axis of said cover plate beyond the curvilinear sides of said recesses thereby forming flanges having enlarged opposing faces, with the generally rectilinear sides in each set converging towards each other ending in a curvilinear apex which joins the converging sides, a side of each pair substantially at a forward apex at said one end of said slider and said sides of each pair forming an angle between 30* and 60* to the longitudinal axis of the slider, said curvilinear apexes which join the two sets of rectilinear sides being disposed approximately midway between the longitudinal ends of said cover plates with the width of said cover plates from apex to apex being greater than the longitudinal length of said slider, the outer faces of said slider tapering toward said apexes.