Study On Ultrasonic-assisted Injection Molding Of Glass Fiber Reinforced PC

With the application of plastic products becoming more and more common in industry and our daily life, injection molding technology, as a main forming method of plastic molding, is showing its great superiority and development potential increasingly. High polymer materials is playing an increasingly important role in all walks of life for the characteristics like light quality,high specific strength, low processing cost, convenience for mass production.Glass fiber-reinforced PC has good mechanical properties. It is widely used in agricultural machinery equipment. However, it ’ s more likely to appear short shot, warping and stress cracking because of its high melt viscosity, poor liquidity and filling difficult.Ultrasonic field effecting on the melt is proposed in this paper based on the analysis of the mold technology research status for researching if ultrasonic is beneficial to improve the liquidity, tensile strength, glass fiber oriented and if ultrasound will reduce the plastic’s glass transition temperature for its cavitation effect.Based on characteristics of injection molding process and analysis of the theory of ultrasonic vibration, the umbrella hook molded part who has thin flat shape and large pressure lose on the melt flow direction is regarded as the research object. Combining with CAE simulation, the mold gating system, cooling system and exhaust system are designed and finishing the design and processing of the ultrasonic-assisted mold structure. The best injection molding process parameters except injection pressure are achieved by means of a combination of orthogonal experiment, single factor experiment and mold flow analysis. The plastic injection molding is conducted in both no exerting and exerting ultrasound, then sampling. By comparing the masses of molding plastic parts with no exerting and exerting different power ultrasound, that the masses of plastic parts molded with ultrasonic is greater than those molded without ultrasonic is found and the higher the ultrasonic power output, the greater the mass.Thus phenomenon indicate that ultrasound is helpful to improve the cavity fill rates of glass fiber reinforced PC. Tested the tensile strength of plastic forming parts with no exerting and applying ultrasonic by the universal material testing machine, the parts molding with ultrasound have greater tensile strength than those without ultrasound. It is guessed that the mechanics performances improved because of ultrasound’s helpful to the glass fiber orientation of forming parts. Observed and shot three positions’ nanostructures of plastic core layer by a 3D laserscanning microscope, the parts molding with ultrasound have better glass fiber orientation of core layer than those without ultrasound,this suggests that the ultrasound is helpful to improve the melt glass fiber orientation. So the above guess that ultrasound is helpful to forming parts’ mechanics performance by improving their glass fiber orientation is verified. Conducted thermal analysis in differential scanning calorimetry, the glass transition temperature of plastic molding with ultrasound is lower than those molding without ultrasound. But the range is small.