The utility model discloses a
welding forming device for a large-and-small-head
titanium pipe fitting. The large-and-small-head
titanium pipe fitting is provided with a middle section, a large-head section and a small-head section, wherein the diameters of the two ends of the middle section are different, and the large-head section and the small-head section are located at the two ends of the middle section and are of a straight cylinder structure. The large-head and small-head
titanium pipe fitting is of a split structure, and the
welding forming device enables a middle section, a large-head section and a small-head section to be coaxially and detachably connected through ports. The
welding forming device comprises flat attaching rings which are sequentially sleeved and attached to the outer surface, close to the two end openings, of the middle section, and the outer end of each flat attaching ring horizontally extends to form a positioning ring for positioning and penetrating the large-head section and the small-head section. According to the welding forming device, the large end section and the small end section which are split can be coaxially positioned with the middle section respectively, welding operation is carried out after positioning, the
welding defect caused by the fact that the middle section is difficult to place stably can be avoided, and therefore the coaxiality, namely the sealing performance after welding is improved, and the welding quality is improved. The problem that pipe body cracks are prone to being caused when a
reducer pipe fitting is integrally formed at present is solved, the yield is increased, and the
machining cost is reduced.