Abstract: A method for manufacturing a beam (P1, P2) with closed section, the beam being produced by combining a first profile (P10, P20) and a second profile (P11, P21), including the following steps: producing the first profile by a first stamping of a first plate (5, 50) between a first punch (1, 10) having a first imprint and a second punch (2, 20) having a second imprint and incorporating a core (3, 30) modifying its second imprint; holding the first profile (P10, P20) on the first punch and positioning the core (3, 30) above the first profile (P10, P20); producing the second profile (P11, P21) by a second stamping of a second plate (6, 60) against the core (3, 30) between the first punch (2, 20) and the assembly formed by the superposition of the first punch (1, 10), the first profile (P10, P20) and the core.