Research on oversized load packaging

Modern packaging is rapidly developing in all industries. The development of packaging in agriculture, processing, and construction industries is intensive due to a significant share of large-sized cargo (styrofoam plates, rolls of mineral wool, fuel briquettes from agricultural and forest biomass, etc.). Therefore, the urgent task is to create equipment for high-quality packaging of large cargoes. During the large-size packaging process, the stretched film is welded. One of the problems is the need to tighten the package with a film, to ensure the density and strength of the welds, which will withstand the stretching of the film after sealing the formed package. The design of such machines is specific because it includes both the mechanisms of forming the package and the mechanisms of wrapping it with a film followed by welding. A model of the process of welding polymer films with a thickness of 25–200 μm was built, which describes the dependence of the quality indicators of the packaging on the technological modes — the temperature of the heater, the duration of welding, and the pressure during welding. The welding contact pressure depends on the viscosity of the packaging material and its softening temperature, and it is greater for a higher viscosity of the material. It should be noted that pressure affects the strength of welds at low heater temperatures and short heating durations. At the heater temperatures of 250–290 °С, the pressure practically does not affect the strength of the welds. Analysis of the deformation properties of the films shows that the amount of tensile stress for these films in packaging equipment should not exceed 10–12 MPa. Deformation of 5–7% for polyethylene films is completely reversible, if this threshold is exceeded, the film package will lose its shape. A new roller mechanism for welding and cooling the film is described. An experimental setup has been developed for researching the process of packing large cargoes. The dependence of the quality of the welding seam of the packaging film on the temperature and force of its welding, as well as on the duration of heating and cooling of the seam, was determined experimentally.