Abstract: The outside convex surface of the bent plate forming the trough of a rotating cylinder type ironing machine is carved with two grooves which run parallel to its bending axis and divide the trough into three equal curved sectors. Each of these grooves providing, by reduction of the thickness of the said plate, an axis of less resistance of the latter to bending, such that the adjustable supports of the trough against the outer lining wrapping the rotating cylinder of the machine by the slight bending of the trough occurring along each of the said grooves, regardless of the temperature and the expansion of the trough.