Drawing extrusion-torsion machining device and method for gradient structure bar

The invention discloses a gradient structure bar drawing extrusion-torsion machining device which comprises a bottom plate, a sliding base and a driving base are arranged on the upper surface of the bottom plate, the driving base is fixed to the bottom plate, the sliding base can slide towards the driving base, an anti-rotation base is arranged between the sliding base and the driving base, and the anti-rotation base is fixed to the driving base. The anti-rotation base can slide in the sliding direction of the sliding base, a torsion driving motor is fixed to the sliding base, a drawing driving cylinder is fixed to the driving base, a driving shaft and a driving rod are arranged at the opposite ends of the torsion driving motor and the drawing driving cylinder correspondingly, and bar fixing devices are arranged on the driving shaft and the anti-rotation base correspondingly. A drawing die is arranged between the two bar fixing devices, and the driving rod is fixedly connected with the drawing die through a t