The invention discloses a nodular
cast iron pipe die which comprises a supporting base, a first annular guide rail and a
cast iron pipe die body. The first annular guide rail is connected to the supporting base, the
cast iron pipe die is horizontally inserted into the first annular guide rail in a penetrating mode, and the rear end of the
cast iron pipe die is rotationally connected into the first annular guide rail. A rotating
speed reduction preventing mechanism is connected between the
cast iron pipe die and the supporting base. When the rotating speed of the
cast iron pipe die driven by the main driving motor is reduced, the
centrifugal force is reduced, so that the main
magnet block slides back under the action of resilience force of the first connecting spring, the adsorbed iron sliding block is pulled to be separated from the auxiliary
magnet block and extruded to the
pressure sensing switch, then the position of the auxiliary driving motor is fixed, and after the auxiliary driving motor is started, the
pressure sensing switch is pressed to the
pressure sensing switch. The auxiliary driving gear drives the cast iron pipe die to continuously rotate at a certain rotating speed, rotating speed
recovery and
centrifugal force recovery are achieved, and cast iron pipe manufacturing can be continuously carried out conveniently.