Numerical Simulation Research On The Process Of Polymer Micro-machine In-mold Assembly Molding

Micro-parts assembly processing is the main technical problems of micro-mechanical manufacturing and processing, In-mold assembly molding is an advanced polymer molding technique in which component injection molding process and in-mold assembly process are integrated together and the future important problems of polymer micro-machine molding technique will be resolved. Polymer micro-mechanical manufacturing technical key is to ensure the precision of the size, shape and assembly of motion pair, micro-part is small scale which resulting in very low bending stiffness,and making thermal-fluid-solid coupling interaction between the secondary stage molding high viscosity melt filling flow and the surface of first stage solid micro parts become an the key control parameters of influencing the the polymer micro-mechanical in mold assembly molding products precision. Therefore, the formation mechanism of thermal-fluid-solid coupling interaction in polymer micro-mechanical in mold assembly molding process was systematically studied, and based on gas assisted back pressure, the multi-field collaborative control technology of thermal-fluid-solid coupling deformation was put forward which has laid a scientific theoretical basis and provided technical support for the research and development of Innovative polymer micro-mechanical processing technology. This research has the following innovative results.(1) For the polymer micro-mechanical in mold assembly molding characteristics, With polymer rheology theory, and after reasonable assumptions, theoretical models describing its flow-forming process has been established, the influencing rules of the second stage polymer melt rheological parameters and process parameters on the thermal-fluid-solid coupling interaction effect and deformation in polymer micro-mechanical in mold assembly molding process were systemically studied by means of the one-way coupled method between computational fluid dynamics and computational solid finite element, and its formation mechanism was revealed.(2) The results show that the thermal-fluid-solid coupling deformation increases with increasing of the mold temperature, melt injection temperature, as well as the secondary injection melt zero shear viscosity and rheological index.(3) Based on gas assisted back pressure, the multi-field collaborative control technology of thermal-fluid-solid coupling deformation was put forward. When the gas-assisted back pressure in exit exceeds critical values, gas assisted back pressure not only can effectively reduce the fluid-structure coupling interaction pressure field, but also effectively reduce the coupling temperature field of first stage molding solid micro shaft which can achieve multi-field collaborative Control of thermal-fluid-solid coupling deformation, can effectively control the in mold assembly molding thermal-fluid-solid coupling deformation, and can implement the precise In-mold assembly molding of polymer micro-machine.