| The rapid manufacturing technology of hard injection combines the rapidprototyping technology with the traditional mold reproduction technology, means usingthe material which is different from the final mold material as the transition material,and getting the final desired mold by different processes of reproduction. Thistechnology not only can shorten the manufacturing cycle, reduce the production cost,but also can simply, quickly get the conformal cooling channels, realize rapid coolingand uniform cooling, and improve the quality of the part. The manufacturing technologyof hard injection by spraying is manufacturing injection mold is one of the most widelyused technology.In this study, adopt the gypsum and the alumina ceramic as the basal mold materialof the spraying prototype, and conduct the hard injection reproduction test by theplasma spraying process, the test results show that, because of the low strength, thegypsum mold is prone to breakdown in the spraying processing, so it is different to getthe perfect spraying layer; and although the ceramics mold after sinter has sufficientstrength, the sinter leads to the uneven shrinkage of the different parts of the mold, sothe shape and the dimensional accuracy of the basal mold is hard to guarantee, and itresults in the dimensional accuracy of the final mold is difficult to meet therequirements. Meanwhile, because the spraying layer and the basal mold are hard to beseparated, these technologies are not conducive to the actual production.Based on the above test results, this study proposes that adopt graphite as thematerial of the basal mold, and combine with the plasma deposition forming technology,as the manufacturing technology of hard injection, the processing is that machining thecurved face as same as the parting face on the graphite block, and deposit a metal layeron the surface of the graphite mold by the plasma, then get the desired hard injection bydifferent processes of reproduction. In the reproduction processing, according to the bestcooling method simulated by the software Moldflow, embed the cooling copper tubingin the back lining layer, and get the final hard injection with conformal cooling channels.The main research results by the theoretical and experimental research can besummarized as follows:(1)Gypsum and alumina ceramic are not suitable for the material of the basal moldin the reproduction technology of hard injection by plasma spraying.(2)Because of the good machining property, high melting point and the goodelectrical conductivity, the graphite is suitable for the technology of hard injection by plasma deposition, and the tests show that the deposition layer and the graphite blockare easy to be separated.In order to avoid the warpage of the deposition layer caused in the plasmadeposition processing, it is need to machining a series of diameter-4mm and deep-5mmauxiliary holes on the surface of the graphite basal mold, so the molten metal will flowinto these holes to increase the binding on the deposition layer, thereby eliminating thewarpage.(4)Get the best parameters of the deposition forming process on the graphite basalmold.(5)Master the method of the best optimal design of the cooling channels and theimplementation of the conformal cooling channels in the mold reproduction processing. |
