Bending boom, boom device, and work machine

A bending boom, comprising:

• a middle portion configured to connect an external component;
• and
• two extending portions, each of the two extending portions having a first side wall and a second side wall opposite to the first side wall, wherein the first side wall is flush with the middle portion, and the second side wall is at least partially bent from the middle portion towards a direction near the first side wall;
• wherein the two extending portions are connected to two opposite ends of the middle portion, the first side walls of the two extending portions are connected to two different side walls of the middle portion, and the second side walls of the two extending portions are connected to two different side walls of the middle portion;
• the second side wall comprises a bending section, one end of the bending section is connected to the middle portion, and the bending section is bent from the middle portion towards a direction near the first side wall;
• and
• the bending section is arc-shaped, and a curvature in a middle of the bending section is greater than a curvature on two end portions of the bending section.