A METHOD OF MANUFACTURING A YANKEE DRYING CYLINDER

摘要

The invention relates to a method of manufacturing a Yankee drying cylinder 1 for drying wet fibrous webs W by heat. The manufacturing method comprising the steps of: providing a shell 2 which is a circular cylindrical steel shell 2 with two axial ends 3, 4 and the shell 2 having a diameter in the range of 2 m - 8 m. Circumferential grooves 6 are formed on an internal surface 5 of the shell during some part of the manufacturing process. An end cover 7, 8 of steel is provided for each axial end 3, 4 of the shell 2 and each end cover 7, 8 has a circular circumference. The method comprises welding each end cover 7, 8 to an axial end of 3, 4 the shell 2. According to the invention, each end cover 7, 8 is welded to its respective axial end 3, 4 of the shell 2 at 16 - 32 separate welding points 12a, 12b, 12c, 12d.....12x that are made in a sequence, one after the other, and separated from each other along the circumference of the end cover 7, 8. For at least the first 8 welding points 12a, 12b, 12c, 12d.....12x, the welding points 12a, 12b, 12c, 12d.....12x are made in pairs of two in which the second welding point 12a, 12b, 12c, 12d.....12x in a pair is made directly after the first welding point 12a, 12b, 12c, 12d.....12x of that pair and the second welding point 12a, 12b, 12c, 12d.....12x in each pair is placed at an angular distance along the circumference of the end cover 7, 8 which lies in the range of 175°- 185° from the first welding point of that pair.