The Development Of Gas Assisted Injection Molding Equipment Key Technology For Automobile Complex Plastics Parts

GAIM (Gas Assisted Injection Molding) is an innovative technology of moldingplastics since 1990s. It uses high pressure N2 to push polymer melt filling the mold.Then forces the gas channel inside the plastic part forming a hollow cross section bygas holding, eliminates the shrinkage on plastics surface. The strengthen ribs formingin the gas channel not only enhance the strength of plastic parts, but also supply anew molding method for the uneven thickness and complex shape plastic partmolding. Especially, it opens a new molding area for reducing the weight ofautomobile injection molding parts and electronic appliance injection molding parts.It is known as a technology revolution in the plastic industry. Extensive research andpractice on the GAIM technology were inverstigated in foreign countries. And gotobviously effects and results. But in home the application research of GAIMtechnique is just at beginning.With the rapidly developing of the automobile industry, electronic applianceindustry and the great application potentialities of new kinds of high polymer,engineers and scholars more and more concentrate on the injection molding problemsof the large complicated injection parts, precision injection molding parts andthinwall, high strength plastic parts. It is an effective measure for us to use GAIM tosolve the injection process problem. For these reasons, the main content and researchwork in this paper is founded with the national tenth-five years sceince technologydevelopment project etc. The main study results are summarized as follow:1. In the gas-melt two phases flowing, the theoretical study on the relationshipof part performance and chemical structure for the axial symmetrical part during gasassisted injection molding.It first analyze chemical structure transformation of gas assisted injectionmolding axial symmetrical part using polymer molecule chain dynamics and averagemolecule weight distribution, then indicate innovatively the gas infiltration weightformula with gas injection pressure, polymer melt molecule chain length and theradius of polymer melt molecule dynamics model, which can be useful to forecastgas assist injection molding;at the same time, the part inner surface finish qualitywill decrease if the gas injection pressure is higher or molecule chain length is tooshort.2. It innovatively proposed the integrated closed-loop control arithmetic of theGAIM equipment system.By the test and comparison method, the smith fuzzy control arithmetic fornon-linear pressure regulator and gas assist injection equipment is researched.Traditional PID control arithmetic has good stable response ability, but it has poordynamic response ability;So, the smith fuzzy control arithmetic is proposedinnovatively, it can enhance the suitable ability of the system. By the experiment, thisarithmetic can improve the steady ability of control system and perferably used togas assist injection equipment.3. Study on the gas assisted molding process of automobile complex injectionpartUsing automobile complex injection molding part such as car bumper, tidy,truck handle etc, the gas channel design and its layout is discussed, then the structuredesign step for automobile complex gas injection molding part is provided. And byrepresentative part gas assist molding numerical analysis, the reason andcountermeasure for gas assisted process defect is investigated. It can be guided forgas assist injection part design and process molding.4. Designed the physics simulation mold for automobile injection molding part.Using truck handle and Jieda car bumper, the physics simulation mold isdesigned. And by production test, the main process settings of truck handle and carbumper is: melt shot, gas injection pressure and gas delay time, these settings havehigh influence on part molding quality.5. Firstly developed gas assisted injection molding equipment dynamic monitorapparatus.By infrared sensor, light and high speed video camera, gas assisted moldingmultimedia data collected from Jieda car bumper physics simulation mold, andcorresponding data processing and identificatin method is proposed.