The five-layer co-extrusion internal-external cooling automatic roll-changing blown film machine is applicable to all kinds of high-end packing applications like food, medicine, hygienic materials, and electronics. Featured with high efficiency, the machine produces films with high transparency, little crystallization, little thickness errors, and good evenness free of wrinkles, etc. The five-layer co-extrusion internal-external cooling automatic roll-changing blown film machine is made with exquisite design, with all the critical parts analyzed with CAE to guarantee the strength and rigidity. Dies are designed with 3D simulation and go through hot fluid analysis to guarantee smooth runner and reasonable gap. Dies are processed with top-quality forged die steel, and later go through tempering, aging, preliminary working, and finish machining, so that to eliminate to the max. extent the deformation from high temperature. Both die steel and dies are multi-axis NC machined, while the inte