Abstract: The bending machine for the production of rectangular sheet metal panels includes a vertically traversing blank holder which is formed of a plurality of blank-holding elements, two end elements and two spacers, a fixed counterblade, two opposing blades fixed to a vertically traversing C support and structure for positioning the metal sheet to be bent on the counterblade. There are provided on the machine programming elements traversing along the blankholder to vary the side extension of said blankholder according to the dimensions of the metal sheet to be bent. There is also provided the possibility of expanding and contracting the blankholder sidewise at the beginning and at the end respectively of the bending operation of a long side of the metal sheet.