Visualization Research On Polymer Filling Flow Characteristics Of Ultrasonic Assisted Injection Molding

Ultrasonic technology is recognized as a new technology combining with physics, vibration, acoustic and other disciplines. With the further investigation of scientists in ultrasonic technology, ultrasonic technology has been widely used in biomedicine, materials science and other fields. As a new kind of polymer molding method, ultrasonic-assisted injection molding successfully put ultrasonic in molding to play its benefits in reducing melts viscosity and improving products quality. But it is still not clear of how ultrasonic vibration affects melts flowing and the mechanical of ultrasonic vibration to melts flowing. Therefore, aiming at this question, visualized trace method was used in this paper to study the influence of ultrasonic vibration on polymer flowing.Choosing rectangular plate plastic parts as research object, an injection mold combining ultrasonic with visualization technology was designed, which realized multi-position ultrasonic excitation. Using this mold, injection molding experiments of different ultrasonic power and injection rate parameters were done. And the influence of ultrasonic vibration on PP melts flow traces, direction of plastics contraction and melts flow velocity were investigated with the method of trace notation and polynomial fitting. On the one hand, it was found that ultrasonic vibration made melts remain a longer straight flow distance in cavity. Besides, plastic shrinkage balance point was moved to the end of cavity. On the other hand, PP melts front flowing was promoted to a certain extent, with the biggest improvement of35.2%. Meanwhile, the tendency of melts front flow rate curves declined rapidly, then showed a tendency of shaip rise, lower again, rising again and finally dropped.A method of characterizing melts flow velocity field was proposed with the help of trace notation technique and Kringing interpolation method. On the one hand, the experimental data showed that the distribution of melts flow velocity tended to be high in the middle and near the entrance of the cavity, while low on both sides and the end of cavity. By the influence of ultrasonic vibration, melts flow velocity was promoted and the gradient of melts flow velocity was decreased along melts flow direction. On the other hand, from the size of melts flow velocity and the uniformity of viscosity distribution consideration, the enhancement of melts flow velocity was the most obvious when ultrasonic power was800W for lmm cavity with600W,400W and100W followed. But for3.5mm cavity, ultrasonic power of200W had the biggest influence to melts flow velocity,800W and100W followed.