The utility model relates to the technical field of inner step
forge piece forming, in particular to a mandrel for
forging an inner step hole, which comprises a first carrier and a second carrier which are respectively positioned on two sides of a mandrel, the outer diameters of the first carrier and the second carrier are smaller than or equal to the inner
diameter of the mandrel, and the two carriers are connected with the mandrel in a
welding manner and are provided with guide inclined surfaces and transition cambered surfaces; a detachable
forging die
assembly is arranged on the mandrel and is of a split structure, and
forging grooves are formed after the forging die
assembly is installed at the two ends of the mandrel. The forging die
assembly is composed of two coaxially-arranged
saddle sleeves, working cavities are formed in the
saddle sleeves, and arc-shaped buckles are arranged at the bottoms of the
saddle sleeves. According to the forging die, the stability during forging of an inner stepped hole can be improved, the forging grooves formed by replacing the forging die assemblies of different specifications can adapt to forgings of different specifications, tool cost is reduced, resource waste is reduced, when the forgings are clamped, the forgings can be taken out quickly only by lowering the forging die assembly on one side, and destructive taking out and secondary
machining are avoided.