| The mold temperature of rapid heating cycle molding(RHCM) is changing during all the production period. During the filling stage, the mold temperature is maintained at a relatively high temperature. After the filling stage, the mold is cooled rapidly in order to shorten the molding cycle. Using this technology, high quality plastic parts with excellent appearance and no weld marks can be produced, and fiber exposure on the part surface can be avoided as well. Especially, the subsequent processing processes,such as spraying can be eliminated, which can realize green production. Compared with conventional injection molding(CIM), the processing technique of RHCM will be more complex and demanding high requirement of process parameter, so it is easier to happen quality problem with product, such as shrinkage, war-page and sink marks. Numerical simulation technique can be powerful means to solve complex problem in engineering.The mold temperature of CIM technology is constant. However, it is transient in RHCM process. For this reason, the CIM process simulation methods can not be applied to simulation in RHCM process. Therefore, the numerical simulation method of RHCM process is studied. And combined with the optimization design theory, quality control of product with RHCM process is researched. The main research work and achievements include:① The numerical simulation of Water-assisted RHCM process is studied. The hot water of 180℃ and 1MPa was used as heating medium to realize the rapid change of the mold temperature, the W-RHCM finite element model is constructed based on Moldflow, the filling +packing +cooling +warping of W-RHCM process is simulated.Finally, some results were obtained, such as pressure, temperature, time and cooling result, etc.② The influence of process parameters on product quality with RHCM is investigated. An air-conditioning panel plastics was taken as an example in the research of RHCM. The sink marks, volumetric shrinkage and war-page of the product are considered as quality evaluation indexes. On the basis of the numerical simulation of Water-assisted RHCM process, the Taguchi Experimental Design and single-factor experiments were applied to study the effect of the mold temperature on product quality,and the effect of other process parameter on product quality under different mold temperature was also studied, such as melt temperature, packing pressure, packing timeand cooling time. The influence law of process parameter on sink marks and war-page as well as volumetric shrinkage was obtained, and the reason for the defects was also analyzed.③ The W-RHCM process optimization technology is researched. An multiobjective optimization strategy based on Computer Aided Engineering(CAE) analysis,experimental design, Kriging meta-model and genetic algorithm was proposed. The optimization strategy was used to optimize the processing parameters of an air-conditioning panel plastics with RHCM, finally, the optimal process parameters were heating time of 36.9s, melt temperature of 182.9℃, packing pressure of 88.5MPa,cooling time of 51.3s, injection time of 2.2s, packing time of 8s, and CAE analysis achieved good results, showing that the optimization process parameters were reasonable.④ Production trial. The optimization design of process parameters was applied to trial production. As a result, the actual production achieves good result and the product quality can meet the requirement, which shows that the optimization strategy is feasible and reasonable. At the same time, the research work can provides feasible plan and guidance for the process development of RHCM technology. |
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