井架使用过程中,其结构要承受很大的载荷和遭受腐蚀,因而降低其强度并于焊接处产生疲劳损坏。井架零部件中井架天轮占有很重要位置,其中受载最大的零件是轴。在轴的台阶圆角处和天轮的边缘处可能产生裂纹并进而发展成疲劳裂纹。 During derrick use, its structure is subject to significant loads and corrosion, thereby reducing its strength and causing fatigue damage at the weld. Derrick parts in the derrick occupy a very important position, of which the largest load is the shaft parts. Cracks may develop at the fillet of the shaft steps and at the edges of the sheave and further develop into fatigue cracks.