A C-shaped frame for a cold-joining tool has two leg sections spaced apart from one another and a connection section. A punch unit and a die unit are provided opposite one another to define a tool axis. The C-shaped frame has a first surface side and a second surface side. An outer contour of the C-shaped frame is determined by an outer edge of the C-shaped frame in the transition between the two surface sides. The C-shaped frame includes a reinforcing section provided on the outer edge along the outer contour of the C-shaped frame. There are multiple portions of the reinforcing section, each with an associated thickness dimension of the portion, over a profile of the reinforcing section as seen along the outer edge. The extent of the respective portions along the outer edge and parallel to a surface side is in each case at least 30 millimetres.