Process for manufacturing a metal part

A process, comprising:

• supplying a metal blank defining a rectangular cross-section, extending in a first direction (Y) from one first direction end to the other first direction end, extending a second length in a second direction (Z), perpendicular to the first direction, from one second direction end to the other second direction end, and extending a third length in a third direction (X), perpendicular to the first and second direction, from one third direction end to the other third direction end;
• at least one step of removing material from the metal blank so as to form an intermediate part including a central member extending in the first direction, a junction zone at one end of the central member, and at least first and second intermediate side members, which define first and second intermediate side member lengths, extending in parallel in the first direction from said junction zone away from the central member with a space between the first and second intermediate side members that extends the entire first length in the first direction, that extends a distance that is less than the entire second length in the second direction to the junction zone, that extends a distance that is less than the entire third length in the third direction, and that occupies the entire volume defined by the entire first length, the distance that is less than the entire second length and the distance that is less than the entire third length;
• at least a first hot forming of the intermediate part by heating the intermediate part in a furnace, followed by clamping the central member of the heated intermediate part between two mobile elements of a die to block movement of the heated intermediate part in the first direction and in a transverse direction perpendicular to the first direction and with the junction zone and the first and second intermediate side members located above the mobile elements, and then spreading the first and second intermediate side members by inserting a first punch between said first and second intermediate side members, so as to obtain a metal part including the central member and first and second side members that extend in different directions and that define first and second side member lengths that are equal to the first and second intermediate side member lengths.