Binder for panels

Claim 1

A binder for panels, comprising a main binder part and a wedge member, said main binder part being formed of a tubular shaft, a flange of a prescribed thickness disposed on the peripheral surface substantially in the middle of the longitudinal extent of said tubular shaft, four slits inserted perpendicularly into the upper and lower shafts on the opposite sides of said flange inwardly from the outer ends of said upper and lower shafts with the directions of said slits coinciding on the opposite sides of said flange, said slits dividing the upper and lower shafts each into four split portions in a manner producing a phase difference of 90° on the opposite sides of said flange, and raised portions formed one each on the inner wall surfaces of one of the two pairs of opposed split pieces on the upper and lower sides of said flange, said selected pairs of opposed split portions involving said phase differences, and said wedge member being formed of a shank portion having a cross section of the shape of an oblong rectangle and a head portion integrally disposed at the upper end of said shank portion, with the opposite narrower surfaces of the shank portion diverged upwardly in the upper portion of said shank portion bordering on the lower side of said head portion, whereby said wedge member is opposed to either of the end faces of the upper and lower shafts of said main binder part and then passed through the cavity enclosed with the four split portions and pushed into the four split portions on the opposite side so that the narrower surfaces at the leading end of the shank push outwardly the raised portions formed on the inner wall surfaces of one of the pairs of opposed split portions and expand the pair of split portions and, at the same time, the diverged portion at the upper end of the shank portion forces its way into and consequently expands the other pair of opposed split portions containing no raised portion.