Results of industrial research

As part of the ongoing project “R&D work on the development of a WPW sandwich panel and core manufacturing technology”, numerical studies using the finite element method were carried out for single-layer panels and simulation models corresponding to the designed three-layer panels were created, which revealed that the introduction of additional layers with improved mechanical parameters would significantly improve the behaviour of the panel under load. The results of the numerical studies carried out preliminarily confirmed the validity of implementing an innovative multi-layer panel with a PIR core with improved physical parameters.

In the next stage of the research, optimum foam formulations were tested in the laboratory using the Foamat device, which met the established requirements for mechanical properties. During foam growth, process times (i.e., growth, gelation and dry face times), the foam growth profile (i.e., growth rate over time, growth pressure) were determined. Based on an analysis of the results obtained and a visual assessment, formulations were selected that met the pre-defined criteria.

After selecting the formulations, suitable PIR foam samples were prepared using a high-pressure device, and then tested for density, compressive strength, Young’s modulus, tensile strength, heat transfer coefficient and adhesion to the cladding. The obtained test results indicated an improvement in the durability of the foams, which proved to be consistent with the results of the numerical studies carried out previously. In the next step, assumptions were made and the relevant operating parameters of the production line dosing threads for the individual layers of the three-layer panel were determined. Using 3D printing methods, a number of different mixing elements included in the mixing system were designed and tested. As a result, a prototype of the proprietary mixing system was created, taking into account the existing dependencies between the properties of the polyurethane foam and the cellular structure of the core.

Due to the challenges of dosing the three layers, prototypes of the nozzles were designed and manufactured separately for each layer using 3D printing technology. Using the completed prototype mixing and dosing system, samples were made and tested for mechanical properties and heat conductivity in the laboratory. The obtained polyurethane foams consisting of three layers showed an improvement in the mechanical parameters in relation to the reference values. As a result of industrial research, a completely new, proprietary mixing, dosing, and pouring section was developed and is currently in the implementation phase on one of our polyurethane-core panel production lines. In the near future, we will present the finished product – a sandwich panel with a three-layer core.