Joint for modular frame construction

Claim 1

A releasable joint for modular frame construction comprising a first and a second elongated frame member and a connector member for releasably securing said two frame members together, each frame member having a T-shaped slot extending longitudinally of the same and defined by a channel opening at an external face of said frame member and by an inner chamber wider than said channel and defining internal face portions of each side of said channel, said first frame member having a transverse and flat end face, and further including a central tubular portion defining a cylindrical bore extending longitudinally of said first frame member and opening at said end face, said connector member made of a harder material than that of said frame members, and having a cylindrical portion which has longitudinal serrations and which slidably engages within said bore of said frame member, said connector member further having at one end of said cylindrical portion an outwardly-projecting enlarged head engaging into the T-shaped slot of said second frame member, said head having an inner contact face which has radial serrations and which faces said internal face portions of said second frame member, said cylindrical portion having a groove circumferentially formed around the same intermediate the ends thereof and defining opposite said head a camming surface which is radially inwardly inclined towards said head, and a screw threaded transversely in said tubular portion of said first frame member, having an outer end accessible through said T-shaped slot and having an inner end engaging said camming surface; tightening of said screw both axially and laterally displacing said cylindrical portion within said bore to cause the radial serrations of said head to dig into said internal face portion and press said second frame member laterally against the flat end face of said first member and to cause those longitudinal serrations of said cylindrical portion which are opposite to said screw to dig into said tubular portion, whereby relative rotation of said two frame members about the axis of the bore of said first frame member is prevented and said radial serrations also prevent movement of said head along the T-shaped slot of said second frame member.