The automatic film thickness control simulation for multi-layer co-extrusion blown film machine

The multi-layer co-extrusion blown film machine is capable of producing composite films with multiple advantages by integrating materials with distinct properties, thereby endowing the film material with excellent barrier performance and high strength. The automatic air ring can dynamically adjust the cooling rate of the film bubble at various angles in real time via its air temperature and air volume regulation control system, which enhances the uniformity and precision of film thickness and consequently ensures the quality of the multi-layer co-extrusion composite film. Based on an investigation into the working principle of the automatic air ring and considering the airflow characteristics within it, a turbulent model for the automatic air ring flow field for the multi-layer co-extrusion blown film machine has been established using the Realizable k-ε flow field model. This study analyzes and investigates the automatic air ring flow field of the multi-layer co-extrusion blown film machine from perspectives such as air ring structural parameters and blown film process parameters. Furthermore, the coupling mechanism of multiple physical quantities during film bubble shaping is explored, and the control parameters of the automatic air ring flow field are optimized. By regulating the flow state of the cooling air within the automatic air ring, the film bubble stability is ensured. A multi-physical field coupling experimental study of the multi-layer co-extrusion blown film machine elucidates the regulatory mechanism of process parameters on film thickness distribution: increasing the inlet air temperature by 20 K accelerates the film thickness thinning rate; an asymmetric air door layout reduces the film thickness fluctuation range while minimizing the temperature difference to 0.53 K. Through collaborative optimization of temperature and air volume, both the film thickness uniformity and the bubble stability are significantly improved.