A housing comprises a protection main body and protection covers, the protection main body and the protection covers define a protection cavity, and the protection covers can extend and retract. Multiple protection assemblies are arranged on the housing, each protection assembly is provided with a welding area communicated with the protection cavity, the welding area penetrates through the protection assembly, and the welding area is used for allowing a tip to pass through and perform welding. A driving assembly is arranged on the protection main body, the driving assembly is used for driving the protection assemblies and/or the protection main body to move so as to enable at least one protection assembly and a corresponding protection cover to move, and the direction of extension and retraction of each protection cover is arranged in the corresponding direction of movement of the protection assembly.