Drying cylinder for a web material machine, particularly a paper machine

Drying cylinder for a machine producing material in webs, and in particular for the cross-direction moisture profile control of a papermaking machine, said cylinder comprising a tubular structure presenting a substantially cylindrical outer surface of circular cross-section having a central axis around which said tubular structure is rotatably mounted and which is subdivided in a plurality of axially contiguous peripheral cylindrical zones against which a web is to be applied, said cylinder further comprising a heating installation including, for each of said cylindrical zones, an individually controlld heating device provided with at least one heating member in radial correspondence with the respective cylindrical zone, with several heating members of said heating installation being axially spaced apart from one another, wherein each of said cylindrical zones is defined by an outer face of one of a plurality of cylindrical rims of a good heat-conducting material and of the same radius, which are coaxially placed side by side and axially spaced apart from one another so that two adjacent rims are separated by a small axial gap, each rim being integral in rotation, by means of at least three substantially radially extending spokes with at least one hub member fixed to at least one shaft rotating about said cylinder aixs, each heating member for each heating device being embedded under said outer face of the respective rim so that each said heating member is in conduction heat-exchange relationship with said respective rim, and each said heating device being further provided with one electrically operated control member for simultaneously actuating all said heating members of said respective heating device and which is fixed to at least one of said respective hub members and spokes connecting said respective rim to at least one respective hub member.