The invention relates to a
tower drum doorframe gradually varied in thickness. The
tower drum doorframe gradually varied in thickness is shaped through integrated
forging or
casting, of a ring structure, and formed by sequentially connecting the doorframe upper end, the doorframe lower end and the arc doorframe middle together, and a smooth transition is adopted among the doorframe upper end, the doorframe lower end and the doorframe middle. The outer side wall of the
tower drum doorframe gradually varied in thickness is connected with the side wall of a tower drum door opening. The outer wall of the tower drum doorframe gradually varied in thickness is of the same
radian as the outer wall of a tower drum, and another smooth transition is adopted between the inner wall of the tower drum doorframe gradually varied in thickness and the inner wall of the tower drum. The thickness of the inner side wall of the tower drum doorframe is larger than the thickness of the outer side wall of the tower drum doorframe, and the tower drum doorframe gradually varied in thickness and the walls of the tower drum are connected through full penetration
butt welding seams. Compared with annular reinforced doorframes usually used at present, the full penetration
butt welding seams are used to connect the tower drum doorframe gradually varied in thickness with the walls of tower drum,
stress concentration on the connecting
welding seams is reduced,
fatigue stress amplitude of the
welding seams is reduced,
fatigue resistance of the
welding seams after being ground flush is high, and simultaneously the tower drum doorframe gradually varied in thickness can prevent the walls of the tower drum at the bottom of the tower drum doorframe gradually varied in thickness from being thickened, reduces welding quantity and
welding deformation of the welding seams between the walls of the bottom tower drum, among the walls of the tower drum and the tower drum doorframe gradually varied in thickness, and among the walls of the tower drum and a
flange at the bottom of the tower drum, improves economical efficiency of the tower drum, and reduces transportation difficulty. The tower drum doorframe gradually varied in thickness nearly has no effect on low order self-vibration characteristics of a wind
turbine generator tower.