Research On High Efficient Cooling Technology Of Injection Mold Based On Nanofluids

With the application of PET bottles to expand, its demand will significantly increase.Correspondingly, how to adapt to the market demand for the production of bottle preform mould, to ensure the high efficiency and high quality production is the development direction of the bottle preform mould in the future.Actually, injection molding process is a heat exchange process, and the heat exchange efficiency of the cooling medium is the main influence factor of the efficiency of bottle preform mould production.Nano fluid, as a new type of high efficient heat transfer fluids, after about 20 years domestic and foreign research,has been made a series of achievements.But as a medium of injection mould cooling application, it is still in a blank state.In this paper,it is of importance scientific value and engineering significance to apply the nano fluid to the cooling of the injection mold and carry out the related research.Firstly, according to the several stages of Injection molding cycle, and the structural characteristics of the injection molding cycle, the main influencing factors of injection mold cooling system on plastic parts were analyzed,and the cooling circuit of bottle preform mould cavity was improved.Subsquently, the mechanism of enhanced heat transfer characteristics of nano fluid was analysed.Some important research results of mathematical model in recent years the domestic and foreign scholars on the nano fluid thermal properties was summarized.A suitable model for the heat exchange of the cooling medium in the bottle preform mould was selected.Cuwater nanofluid thermal properties, particle size of 50 nm,were calculated including density,specific heat capacity, viscosity coefficient and thermal conductivity.In the following,A mathematical model for the cooling of PET bottle preform mould was established.Through of flow state analysis of water and nano fluid.The effect of the use of ordinary water and nano fluid as the coolant on the production efficiency was analyzed with Moldflow software.It is proved that the cooling time of the mould is shortened by using the nano fluid, the temperature difference of the mould is reduced, and the thermal stress of the mould is reduced.At last, the experiment was carried out.Through the cooling experiments of copper tube, the efficient cooling characteristics of the nano fluid were verified visually.Then the experiment was carried out by using the 25 g bottle preform one mold two cavity mould as the cooling experiment object, with the water and the mass fraction of 0.2%, 0.6% and 1%,respectively.In order to facilitate the cooling effect of contrast, set the cooling time of themold is different, 14.5s, 14 s, 13.5s, 15 s, 8s;Each ten as a set of detection, then take its average;The cooling effect of the cooling liquid is judged according to the different parameters such as the weight of the bottle preform, the eccentricity and the distribution of the stress line.The experimental results show that the nano fluid can significantly improve the distribution of the stress line of the bottle preform, reduce the eccentricity of the bottle preform and shorten the cooling time, which can effectively improve the cooling effect of the PET bottle preform mould.