Injection Molding Technology And Mechanism Of Synchronous Plasticizing And Mold Filling By Eccentric Rotor Based On Volume Elongation Flow

As one of the most important processing methods in production of plastic products,injection molding has the advantage of production speed,high efficiency,precise dimension,etc.And it is widely used in food packaging containers,medical equipment,household appliances accessories,auto parts,aircraft transparent parts,etc.However,the traditional injection molding is a kind of intermittent molding method which means that plasticizing and mold filling process are carried out step by step,that is to say,it is only able to complete an specific injection molding process in a period of time.Thus it greatly reduces the working efficiency,increases the injection cycle time and energy consumption of the injection molding machine.In addition,the backing of screw in the process of material plasticizing shortens the screw effective length so that the material plasticizing effect is poorer and it is difficult to achieve polymer blending modification and in-line long fiber reinforced plastic.Moreover,the friction resistance and energy consumption increase because a lot of un-plasticized materials in the barrel participate in the linear motion of injection process.The injection speed and position is difficult to accurately control,which affect the quality and mechanical properties and limit the further application of products.This work innovatively combines volume elongation deformation plasticizing transport technology,energy-saving injection compression molding technology and cavity hot runner injection molding technology,and put forward the injection molding method of synchronous plasticizing and mold filling based on eccentric rotor volume elongation deformation for the first time.Based on reasonable assumptions,the mathematical and physical model of synchronous plasticizing and mold filling injection molding process has been created.The influence of melt temperature,rotor speed,compression stroke,and compression speed of injection molding process on the measurement precision of plasticizing,energy consumption of the before-plasticizing stage,the synchronization plasticizing and injection stage,and the compression-filling stage have been revealed for the first time,which can provide a theoretical basis and guidance for practical production.The eccentric rotor synchronous plasticizing and mold filling injection molding machine has been successful developed for the first time,and the experimental research of plasticizing measuring accuracy and the energy consumption of the before-plasticizing stage,the synchronization plasticizing and injection stage,and the compression-filling stage has been carried on to verify the correctness of the theoretical model.The results show that the experiment and theory has good consistency.The continuous injection molding of LDPE thin-walled products are successfully realized by adopting the eccentric rotor synchronous plasticizing and mold filling injection molding machine.And the effect of forming process on quality uniformity,thickness distribution,and tensile properties has been explored to verify the feasibility of synchronous plasticizing and mold filling injection molding technology.The results show that the thin-walled products have smooth surface and good appearance quality,no obvious buckling deformation,flow mark,bubble and burr.The thin-walled products prepared in the same molding process parameters has small quality deviation and good quality repeatability.When the rotor speed is 15 r/min,the average quality of product is 15.05 g,which has good consistency compared with the standard quality of 15.04 g.Different processing parameters only changes the thickness value of the products,but not changes the overall thickness distribution trend.When the compression rate is 15 mm/s,the average thickness deviation of thin-walled products is 0.017 mm which is close to the standard values.Moreover,this work successfully verifies the feasibility of using extrusion grade HDPE to prepared products by eccentric rotor synchronous plasticizing and mold filling injection molding machine,and explore the effects of melt temperature on the properties of products.In addition,the LDPE/PLA blend and its OMMT nanocomposites products are successfully prepared by the eccentric rotor synchronous plasticizing and mold filling injection molding machine and the effect of different process parameters on the microstructure,mechanical properties and crystallization behavior is studied.The experimental results show that the dispersed phase PLA is evenly dispersed in the LDPE matrix and has good mixing dispersion effect.The PLA disperses more evenly and has a better compatibility with the decrease of the melt temperature and the increase of rotor speed.The layer spacing of OMMT in the nanocomposites is more increased obviously than that of pure OMMT nanoparticle,and a better dispersion and stripping effect can be obtained under high rotor speed.The successful development of eccentric rotor synchronous plasticizing and mold filling injection molding machine based on volume elongation deformation changes the traditional injection molding method with asynchronous plasticizing and mold filling,and the injection molding method with synchronous plasticizing and mold filling is successfully implemented.Non-enclosed products of single system and blending system with good appearance quality,dimensional accuracy and mixed dispersion effect are prepared.This will promote the development and application of injection molding technology and equipment,and has a great economic value and practical significance.