Integrated system for design and products quality control based on additive technologies for high-tech industries
The article describes the functional structure of an integrated computer system that allows choosing the equipment for 3D printing on the basis of information and mathematical models to study the quality of printed high-tech polymeric and ceramic materials, as well as the necessary mode of its functioning. The integrated system includes the modules for selecting 3D printing technologies (extrusion, sintering) and 3D printers, a module for searching for the parameters of equipment for obtaining products of a given quality, a visualization module for simulation results, and a module for generating a product passport. The integrated system can be used as a training and educational system for training specialists in the field of additive technologies, taking into account the study of the complete life cycle of the synthesis of complex products (from studying the properties of composite materials and designing prototypes of products to assessing the quality of printed products). Testing of the computer system, which confirmed its operability, was carried out on the basis of the Engineering Center of SPbSIT (TU), the corporation Klöckner Pentaplast and Virial Ltd. (St. Petersburg). The use of an integrated system at enterprises of high-tech industries allows us to solve the problem of designing and managing the quality of complex products, saving raw materials and materials, which reduce the cost and time of production of high technology products.
METHODS AND TECHNOLOGIES FOR SYNTHESIS OF MATHEMATICAL MODELS FOR EXTRUSION PROCESSES IN FLEXIBLE PRODUCTIONS OF POLYMERIC MATERIALS
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Analysis of the performance of cooling extruders in thermoplastic foam extrusion
The performance of cooling extruders widely used in thermoplastic foam extrusion was analyzed, by numerically solving the equations of motion and heat transfer. Analysis of cooling extruders does not require a consideration of the melting behavior of polymers, thus simplifying the system equations considerably. The flow geometry analyzed was an unwound screw channel of a single-screw extruder, i.e., a rectangular channel of uniform height followed by diverging and converging sections. Due to the cooling of both the extruder barrel and the screw, the heat transfer equation considered includes the terms describing the convective heat transfer in the down-channel direction and the conductive heat transfer in the cross-channel direction, in addition to the terms describing the viscous shear heating. For the analysis, a power-law model was used as the constitutive rheologlcal equation, describing the viscosities of a mixture of a fluorocarbon blowing agent and a low-density polyethylene melt (or polystyrene melt). The parameters in the Theological model were determined using the data of Han and Ma (13). In obtaining numerical solutions of the equations of motion, an integration method was employed to overcome the problem of numerical instabilities. The present analysis predicts the profiles of developing temperature and velocity in the down-channel direction, and the profiles of temperature, velocity, shear rate, and viscosity in the cross-channel direction. In presenting the results of computer simulation, emphasis is placed on the effects of cooling the extruder barrel and screw on the performance of cooling extruders, in terms of the pressure drops along the extruder axis and the mechanical power consumption. This study provides a rational basis for the design of cooling extruders widely used in thermoplastic foam extrusion and for the selection of optimum extrusion conditions in producing thermoplastic foams.