Improved structure of double-wall drill rod

The improved structure of the double-wall drill rod comprises an outer drill rod, an inner drill rod and a wear-resistant sleeve, the outer drill rod comprises an outer rod body, the two ends of the outer rod body are connected with a male connector and a female connector through friction welding, and a welding seam is formed in the inner wall of the connecting position; the wear-resistant sleeve is embedded in the end, connected with the female connector, of the outer rod body, so that a thickened section is formed, one end of the wear-resistant sleeve is limited by a protruding step on the inner wall of the outer rod body, and the other end of the wear-resistant sleeve is limited by a welding seam. The inner drill rod penetrates through the outer rod body, and one end of the inner drill rod is limited by the wear-resistant sleeve in a matched mode. According to the improved structure of the double-wall drill rod, the wear-resistant sleeve is arranged at the position, needing to be thickened, of the outer dr