Installation for forming at least one corner region (1.0) in a rectangular metal plate, the corner region (1.0) being formed in the intersection between a first section (1.1) and a second section (1.2) of the metal plate, the installation comprising - a die longitudinally extending in a longitudinal direction, and comprising a flat upper surface (2.0) extending in the longitudinal direction and on which there can be arranged the metal plate, two opposite side walls (2.21, 2.22), and a front actuation contour (2.1), - a holding device for holding the metal plate against the flat surface (2.0) of the die, - a bending mechanism adapted to perform the bending of both sections (1.1, 1.2) of said metal plate and comprising at least one bending tool extending in the longitudinal direction and comprising a longitudinal central axis (4.0) extending in said longitudinal direction, the bending tool being adapted to bend the section (1.1, 1.2) of the metal plate protruding from the die frontally, pushing said section (1.1, 1.2) against the actuation contour (2.1) of said die with a contact surface, and - actuation means for causing the actuation of the bending tool to perform said bending, characterised in that the installation further comprises at least one holding element which is attached to the bending tool and associated with the contact surface, and which is configured for being arranged facing one of the side walls (2.21, 2.22) of the die while at the same time the bending tool is acting on the metal plate to perform the corresponding bending of a section (1.1, 1.2) of the metal plate, the already bent other section (1.1, 1.2) of said metal plate being kept in place between said side wall (2.21, 2.22) and said holding element during said actuation of the bending tool, the corner region (1.0) being the intersection between said two bent sections (1.1, 1.2). - a die longitudinally extending in a longitudinal direction, and comprising a flat upper surface (2.0) extending in the longitudinal direction and on which there can be arranged the metal plate, two opposite side walls (2.21, 2.22), and a front actuation contour (2.1), - a holding device for holding the metal plate against the flat surface (2.0) of the die, - a bending mechanism adapted to perform the bending of both sections (1.1, 1.2) of said metal plate and comprising at least one bending tool extending in the longitudinal direction and comprising a longitudinal central axis (4.0) extending in said longitudinal direction, the bending tool being adapted to bend the section (1.1, 1.2) of the metal plate protruding from the die frontally, pushing said section (1.1, 1.2) against the actuation contour (2.1) of said die with a contact surface, and - actuation means for causing the actuation of the bending tool to perform said bending, characterised in that the installation further comprises at least one holding element which is attached to the bending tool and associated with the contact surface, and which is configured for being arranged facing one of the side walls (2.21, 2.22) of the die while at the same time the bending tool is acting on the metal plate to perform the corresponding bending of a section (1.1, 1.2) of the metal plate, the already bent other section (1.1, 1.2) of said metal plate being kept in place between said side wall (2.21, 2.22) and said holding element during said actuation of the bending tool, the corner region (1.0) being the intersection between said two bent sections (1.1, 1.2).