The barrel is the same as the extruder and is an important part of the extruder. The barrel cooperates with the screw, the barrel contains the screw, and the screw rotates inside the barrel. When the screw rotates to push the plastic to move forward in the barrel, the external heat is transferred from the outside of the barrel to the plastic in the barrel, and the thread volume on the screw is gradually reduced, so that the plastic in the thread groove is squeezed, flipped and cut. After being cut into a variety of forces, it is uniformly mixed and masticated. As it moves toward the front of the barrel, it gradually melts into a viscous flow state, completing the plasticization of the plastic. The normal cooperation of the barrel and the screw ensures the continuous extrusion molding of the extruder.