STRUCTURE AND METHOD FOR CONNECTING METAL PIPES TO EACH OTHER OR CONNECTING METAL PIPE TO METAL BAR

PROBLEM TO BE SOLVED: To improve the coaxial accuracy by leading a metal pipe or a metal bar into other metal pipe with a space between an outer peripheral part of a tip of the former metal pipe or metal bar and an inner peripheral part of the later metal pipe, and connecting them at a rear part as an interface with the plastic deforming pressure of the inner peripheral member of the first metal pipe. SOLUTION: A first metal pipe 1 is provided with a lead-in hole 11 at a central part of the inner periphery thereof, and provided with an interface part 12 continuously to a rear part of the lead-in hole 11. On the other hand, an outer peripheral part of a tip of a second metal pipe 2 is pressed into or smoothly fitted in the lead-in hole 11 of the first metal member 1 so as to maintain the coaxial accuracy. A rear pipe 22 continued to the peripheral part 21 of the tip is fitted in the interface part 12 in the matching condition, and the inner peripheral member of a rear end 13 of the first metal pipe 1 is connected to a previously formed connection groove 23 at a part or over the whole area or intermittently by the plastic deforming pressure of the plastic deformation by the cold forging.