Convex key type mechanical expansion shaft

The utility model discloses a convex key type mechanical expansion shaft which comprises a slitting pipe core, and a positioning sliding key is connected into the slitting pipe core in a sleeved mode.Locking nuts are installed at the two ends of the slitting pipe core, and mechanical expansion shafts are arranged at the two top ends of the slitting pipe core. A supporting block is arranged in theslitting pipe core, and a convex key base is arranged on the side of the supporting block. A convex key is arranged in the convex key seat; the mechanical expansion shaft is sleeved with an expansionshaft core, and an expansion pipe core rotating bearing is arranged on the outer edge side of the expansion shaft core. According to the utility model, the technical problems of coil collapse and rolling slip caused by the use of a small-inner-diameter paper tube core by a heavy steel coil are solved, the paper tube core is adopted to replace a steel tube core, the cost is saved, the use range ofthe paper tube core is enla