Adaptive Gas Injector And Research On Micro-Foaming Gas Injection Process

Micro-foam injection molded products are used in many industries in industrial production,mainly because they can not only ensure mechanical properties,but also reduce the consumption of raw materials.A very important equipment in the process of micro foam injection molding is the gas injector.The domestic market has been dependent on imports for this equipment.The adaptive gas injector studied in this paper is cheap and adaptable,overcoming foreign monopoly,and can be used for micro foam injection molding through research.And the micro foamed products will appear large bubbles and other defects affecting the quality of products,this paper through the improvement of gas injection process,improve the quality of micro foamed products.Developed an adaptive gas injector and tested it through the microfoaming experiment,shows that this gas injector will continue to inject gas into the barrel when the quick-break valve is closed.The principle of gas injection of the adaptive gas injector is to open the air outlet through the pressure difference between the air outlet and the outside of the gas injector,and there is a certain space in the gas injector.When the quick break valve is closed,the pressure inside the gas injector is still higher than the pressure outside the gas outlet of the gas injector,resulting in the phenomenon of gas injection.The problem of subsequent gas injection of the adaptive gas injector was proved through the combination of high-speed video of the visualization experiment and pressure curve.However,it was also found through the visualization experiment that the gas was dispersed after coming out of the outlet of the adaptive gas injector.If it was used in the micro-foaming experiment,it would be more conducive to the diffusion of gas in the melt.The influencing factors of gas injection process were studied in order to provide guidance for the experiment of microfoam injection molding.By adding an exhaust branch to the gas injection system,the problem of subsequent gas injection during the self-adaptive gas injector gas injection process is solved,and the gas injection process is stabilized.The DOE experiment was designed,and the short-time gas injection process was used to carry out the micro-foaming experiment,and the influence of the experimental parameters on the performance of the micro-foamed product and the amount of gas injection was analyzed.The products produced by the short-time gas injection process have a higher probability of having large bubbles.This phenomenon is due to the fact that in the gas injection process,in order to ensure the required gas injection volume for foaming,the short-time gas injection method must be at the expense of increasing the gas injection pressure difference.If the pressure difference is too high,the result is that the gas is too concentrated per unit time,and the screw is not uniformly mixed,resulting in large bubbles.By adopting the method of long-term gas injection after the pressure of the preformed melt is stabilized,the probability of large bubbles in the micro-foamed product is effectively reduced.