Abstract: Process and apparatus for drilling holes in a shell of a paper machine cylinder, which is in its operating position. The process includes fixing a drilling apparatus to a cylinder adjacent to the cylinder to be drilled, and substantially eliminating influences of mechanical play due to structures of the adjacent cylinder prior to drilling, which includes coupling a support member to the adjacent cylinder to exert tangential forces on the adjacent cylinder, whereby the mechanical play is substantially eliminated.

Abstract: The invention relates to a method of drilling holes to the surface of a dryer cylinder in a paper machine. The main goal of the method is to open and or/widen the drilled holes already made on the dryer cylinder, thus improving the performance of the cylinder.

Abstract: Process and apparatus for operating an apparatus to drill holes in the shell of a paper machine cylinder. The apparatus includes a stationary framework supportable on the paper machine, a feed frame that is radially movable along the stationary framework relative to the shell, and a drive unit. A plurality of drilling modules are coupled to the feed frame, which are rotatable via the drive unit, and the drilling modules include a drive shaft, at least two spindle heads, and at least two intermediate shafts arranged between the drive shaft and the at least two spindle heads, in which at least one of the at least two spindle heads in each drilling module is rotatable about a respective intermediate shaft of the drilling modules.