Study On Forming Without Flash In The Multidirectional Loading Theory And Technology For Thepart With Branch

Multidirectional active load is an ideal forming method for branch-type parts. Comparedto other forming processes, this technology can effectively improve the mechanical propertiesof products and material utilization by controlling the different loading paths, changed stressstate, metal fluidity and decreased forming load. The main advantage is complete themulti-pass operation simply by one step, through which achieve the whole forming of thecomplex parts. However, the main disadvantage is lots of flash appear on the parting surfacein multidirectional active load, which resulted in mold cannot close, follow-up actions cannotcontinue. This cause the promoting of process meets the bottleneck.The paper research theory and methods for realize no flash forming in the active loadingprocess. Study found: the flash occurred in the active loading forming process is attributing tothe unclosed space on the mold, through which the metal can free flow. Based on thecondition, creatively design an active loading mold structure with tooth profile parting, andestablish without flash control forming principle for multi-directional loading. The resultsshowed that: the new mold effective resolves the problem that the appearance of flash duringactive loading process. It provides an important reference for further research and promotionof active load forming process.Through deformation partitioning of the deformable body, tooth profile mold, obtains themetal flow rule in the conditions of active loading. Based on calculates and analysis velocitycomponent, the central compound experiment design has been used for the regression modelof flash quantity (objective function) and tooth profile length, tooth profile thickness andcavity area (design variables). Check for fitting accuracy of the model by the varianceanalysis, and revise the model. Through analysis P value in the analysis variance obtains theimportant order of main effect which influence flash produces. Finally, using the responsecurved surface demonstrated the interaction of each main effect.In view of typical aluminum branch parts, research the structure parameter ofmulti-directional active loaded die by response surface model and fractional factorial designscreening methods. Select the flash quality and active forming loading as load objectivefunction, tooth shaped surface die structure parameter as design variable, optimized design thedie structure parameter. By this, the regression model of the flash quality loading andparameters of mold structure were obtained. With the help of the model with half-normalprobability diagram, design variables and its interaction which significant affect the flashquality and loading were screened.On this basis, the process parameters during multidirectional loading process wereoptimized, study the effects of different process parameters to state variables during theforming process. Using Box-Behnken experimental design to design programme and optimize the formingprocess parameters, obtain the optimal parameters combination(forming speed, temperatureand friction coefficient) and objective function value.Finally, through experimental verification on self-development 12.5MN-3.15MN-3.15MN press,the result show that based on the optimized parameter combination,theflash are almost no produced in the forming process. The difference of crystal grain size ofmicrostructure is small,deformation is relatively uniform, has the better mechanicalproperties.The innovation is: (1) a tooth shaped die has been designed, through which achieve noflash forming.(2) Using response surface method optimized the die structure of parameters foractive load, obtained the regression model of objective function (Flash) and design variables(length b of tooth, tooth thickness and branch cavity area) .(3) The first application offractional factorial design in the multi-directional loading mold structure design, screening thesignificant factor from numbers of design variables, based on box-behnken experimentaldesign, optimized the significant effect factors and provide scientific basis to the die design ofactive load.