| Injection moulding has the advantages of high production speed,high efficiency,and operation flow.It is compatible with the development purpose of Industry 4.0,and it is also an easy-to-implement data production and intelligent production model.The high efficiency of injection molding also determines the high value of the cooling rate of the plastic melt.During the injection molding process,the melt plastic injected into the mold cavity is rapidly cooled from 200?~300 ?to 60?~80 ?in mould opening stage,it requires an excellent cooling system.However,the heat transfer efficiency of cooling systems at the current stage often fails to meet the heat release requirements of large-scale and complex plastic parts.Therefore,according to the enhanced heat transfer technology,this paper designs a variety of conformal cooling systems in order to obtain the optimal heat transfer cooling design method.This paper combines the characteristics of conformal cooling and enhanced heat transfer.A method for enhanced heat transfer of injection moulds with conformal cooling channels was proposed.Firstly,in order to obtain the cooling effect of the curved water channel with surface enhanced heat transfer,the theoretical analysis and calculation of the heat transfer of the conformal cooling channel are carried out.Then,the flow and heat transfer characteristics of water in curved watercourses with different geometric cross-sections were numerically simulated by using computational fluid dynamics(CFD).The effects of channel with different structures on heat transfer were studied by using temperature distribution,pressure drop,and flow velocity as evaluation indicators.Finally,the effect of heat transfer enhancement with conformal cooling channels on product quality was experimentally studied.The main conclusions obtained are as follows:1?The effects of three types of cross-section channels with different inlet-outlet diameter ratios(D/d=1.2,D/d=1.4,D/d=1.6)on heat transfer enhancement were studied.It was found that when the diameter ratio is 1.4,the effect of enhancing heat transfer is better;In addition,the effect of the adjacent channels in arrangement in the same direction(large diameter on the same side)and in the opposite direction is studied for heat transfer.It was found that the channels of arrangement in the opposite direction have better heat transfer effect and cooling uniformity.2?Nine corrugated conformal heat transfer structures have been established.Fluent software was used to simulate the cooling process separately.The results showed that the corrugated curve waterway had better heat transfer effect than that of the equal section channel.In addition,the structural parameters of the corrugated channel are different,and the effect on the heat transfer effect is also different.When D2/D1=1.5 and L2/L1=0.5,the heat transfer cooling effect is optimal.3?The converging-diverging conformal channel cooling channel with scaling ratios of 1:1 and 1:2 were designed,and the cooling performance of both was analyzed by Fluent.The influence of the ratio of expansion and contraction on heat transfer and flow is studied.The curves of the drag coefficient,Nusselt number,and integrated heat transfer evaluation factor with scaling ratio are given.It is found that the heat transfer factors of the two are not much different.4?The three-dimensional model of five transverse grooves was established and flow simulation analysis was performed.The distributions of temperature field,water velocity,and pressure drop field of the channel with different numbers of conformal transverse grooves are obtained.It is found that when the number of grooves is 6,the heat transfer coefficient increases most obviously.5?The products produced by the molds with variable cross-section conformal channel were experimentally studied.It was found that the product's warpage,deformation,mechanical properties and product quality were improved,and the correctness of the above conclusions was further verified. |
PDF Full Text Request