Research On LFT-D Compression-molding Process For Composite Building Formwork

The formwork is one of the basic components in the construction industry,and the vast consumption of wood formwork has led to the serious environmental problems.LFT-D thermoplastic composite has great potential to become a new advanced formwork due to its low weight,high strength and recyclability.The LFT-D composite formwork can be achieved by adding some reinforcing fibers with resin and will be cured in the mold with hot pressing.The final quality of composite will be ensured by proper molding parameters,especially the uniformity of the mold temperature.The structural design,the analysis of molding process,the optimization of mold inserts,and the control of molding temperature have been done,considering the characteristics of LFT-D composites manufacturing.The main tasks are as follows:1)A new composite building formwork is designed to satisfy the needs of the construction industry.Based on the structural requirements and calibration methods of building formwork,the influence law of different reinforcement structures on bearing deformation of the formwork is analyzed.Combined with the curve-type stiffener,the composite formwork structure with high strength characteristics is designed.Some key process parameters that influence the molding quality are clearly obtained,by analyzing the forming process of composite formwork.2)The inserts and cooling system of the mold are designed,based on the characteristics of LFT-D molding process.The insert structure of the composite template forming mold is designed with concept of combined design.The molding parameters of the molding process are analyzed,and a typical insert cooling system of the typical insert is designed by combining the structural features of the insert.The parameters of the mold cooling system are calculated,and a typical insert cooling runner structure is designed.Water blocking sheets are installed on the inserts with cooling water well structure,and on this basis,the influence of cooling medium on the temperature of the template and the insert is analyzed.3)Heat transfer characteristics of the template and the insert in forming are investigated,considering the effect of cooling medium and the internal flow channel.Aiming at the single border frame template and inserts in the form of flow channel,the effects of coolant flow velocity and temperature are analyzed.For the central reinforced templates and inserts,heat dissipation characteristics and preferred structures under different cooling structures are analyzed.Considering internal cooling wells of the insert,the influence of the structural parameters on the heat dissipation characteristics is analyzed.4)The molding process and product quality are analyzed to verify whether it meets the construction requirements,considering the structural design and cooling system analyses of the previous template and inserts.The mold inserts with random flow channels are designed with the concept of 3D printing.Considering the cooling structure for inserts based on conformal cooling runner,its impacts on the molding quality of products are analyzed.The innovation of this paper is to design a new type of LFT-D composite formwork.After the validation of the formwork structure,the temperature control and heat dissipation in the molding process are analyzed,and the typical mold inserts are designed and optimized for the nice temperature control.Therefore,the integrated process of LFT-D formwork is proposed.It can replace the wood formwork and promote the green economy and sustainable development for the construction formwork industry.