The cylinders and the screw stems of the extruder are made of high quality alloy steel with optimum hardness and strong corrosion resistance after nitrogen treatment and precision finishing. The auxiliary machine has a platfrom working table for making operation easy and is equipped with bubble stabilizing ring. Doubgle-rolling and double-cutting coiling unit adopts torque motor to motor to keep proper resion and make even and roll-changing easy. It is used for blowing the various plastic film of low density polyethylene(LDPE), high density polyethylene(HDPE) and linear low density polyrhylene(LLDPE) etc. Which are widely used for packing liquid, industrial products. Garments and textile, ect. And printing lamination.