Dimpling and riveting apparatus

Abstract

Dimpling and riveting a workpiece wherein the workpiece is clamped, the dimpling, drilling and riveting occur sequentially while the workpiece is clamped, and the workpiece is heated prior to dimpling. During clamping a pressure foot force is applied to one side of the workpiece, and during dimpling a force is applied to the opposite side causing slight movement of the workpiece against the pressure foot force. The dimpled recess in the workpiece is about the shape of a truncated cone and a rivet-receiving hole is drilled through the workpiece in the recess. To provide a fluid-tight seal, the minor diameter of the truncated cone is made slightly greater than the diameter of the rivet-receiving hole thereby providing an annular step between the hole and the outwardly diverging wall of the dimpled recess. During upsetting of the rivet the workpiece material is compressed radially around the annular step to provide a fluid-tight seal between rivet and workpiece. A pressure foot contacts one side of the workpiece, a biasing arrangement connected to the pressure foot and to the apparatus frame applies force to the pressure foot, a clamp member contacts the opposite side of the workpiece and a mechanism connected to the clamp member and to the frame moves the clamp member into contact with the workpiece and moves the workpiece into contact with the pressure foot and then moves the clamp and pressure foot with the workpiece therebetween against the pressure foot force during dimpling.