Full circular tube type door frame and manufacturing method thereof

The invention provides a full circular tube type door frame and a manufacturing method thereof, and relates to the technical field of cranes. The manufacturing method of the full circular tube type door frame comprises the steps that the lower cross beam assembly is manufactured; the lower cross beam assembly comprises a lower cross beam and lower subsections fixedly connected to the two ends of the lower cross beam. Manufacturing a connecting cross beam assembly; the connecting cross beam assembly comprises a connecting cross beam, a door frame inclined supporting pipe and upper sections fixedly connected to the two ends of the connecting cross beam, and the door frame inclined supporting pipe is installed between the two upper sections. Fixedly connecting the lower end of the upper section with the upper end of the lower section so as to assemble a lower cross beam assembly and a connecting cross beam assembly; wherein the two upper subsections in the same connection cross beam assembly are fixedly connecte