Avdel Systems Limited

Avdel Systems Limited, a British Company

Advel Limited

Michael Woodrow

Raymond D Lacey

William D Bradley

Albert C Francis

A blind rivet able to be anchored in material such as softwood, without the need to break through the blind face of the material, comprises a tubular shell and a stem which extends through the shell. The shell has a preformed heat at one end of a shank. An end portion of the shank remote from the head has a thinner wall than the main, next adjacent, portion of the shank, and is thus weakened and made more easily expandible. The stem has a plugging portion having an expander head adjacent the thin-walled end portion of the shell, a breakneck, and a pulling portion which projects from the head end of the shell. The expander head increases in diameter away from the pulling portion, and presents a plurality of longitudinal cutting elements generally towards the weakened end portion of the shell. On gripping the pulling portion and pulling the stem, the cutting elements split the end portion of the shell into a plurality of legs, while the expander head enters into the end portion and forces the legs outwardly. The main part of the shank has a smaller diameter bore than the weakened end portion, and resists entry of the expander head.

Blind rivet

A blind rivet, for anchoring in relatively soft material such as softwood, comprises a tubular shell (14) with a weakened portion (19) at the end remote from the head (18), and a stem (15) with an enlarged head (29) having a smooth underhead curve (32). The weakened portion (19) of the shell has four longitudinal V-section grooves (24) on its inner wall. In addition, the weakened portion (19) has a wall thickness which is less than that of the remainder (22) of the shell, the junction between the two parts presenting an internal annular shoulder (23). When tension is applied to the pulling portion (26) of the stem, the stem head (29) enters the weakened portion (19) and splits it apart along the grooves (24) to form legs which anchor in the soft material. The higher strength of the remainder part (22) of the shell prevents the stem head passing beyond the shoulder (23) before the stem fractures at the breakneck (27).

A bush for installation in easily crushed or marred work material such as apertured honeycomb sheet or fibre reinforced plastics material, enables the work material to be secured to a support, by means of a nut and bolt, without damage. The bush has a cylindrical body longer than the thickness of the work, and a flange for abutting a face of the work at one end of the body. The other end of the body has an annular boss which projects beyond the other face of the work, and, peripherally of the boss an annular skirt which during installation can be deformed to provide a retaining flange for engaging the other face of the work. A bolt can then be passed through the bush and a support, and secured with a nut. Only the bush directly engages the work.

Bush having a radially enlarged flange

A blind, self-plugging rivet assembly for securing together two members (42, 43) is of the type comprising a tubular shell (13) with an enlarged head (14) at one end, and a stem (12) which extends through the bore (15) of the shell, the stem having an enlarged head (38) beyond the tail end (18) of the shell. The shell has a weakened zone (19) formed by three slits (22) extending along part of the shell shank and spaced apart equiangularly around it. The stem head (38) lies beyond the shell tail end, and has an underhead surface (39) which is slightly convex and is bounded by a sharp edge (40). The stem has a pulling portion (32) connected by a breakneck to a plugging portion (31) which is an interference fit in the shell bore. Adjacent the breakneck the plugging portion has a cylindrical skirt which, when the rivet has been installed, can be deformed outwardly to lock the plugging portion to the shell. A bead on the stem guides the tool for deforming the skirt.

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Welwyn Garden City, United Kingdom

Michael Woodrow