Papers by Author: Hong Ping An

Abstract: The hot hole flanging process of a connection tube in a thick-wall head was researched by finite element analysis and experiment in this paper. The deforming mechanism, main influencing factor and defects in hole flanging were analyzed. According to the stress state and the flow mode of deforming metal, the hole flanging process can be divided into two stages, that is, blending and hole flanging. Processing parameters, such as diameter of pre-holes, space ratio of die cavity, punch shape and size and their effect on forming were researched. The 1:3 scaled experiment was done in 30MN hydraulic press using A508-Ⅲ steel. The formed connection tube had a good quality and its end face was smooth without any crack. The measuring result showed that the error between simulation data and test data was less than 5%, which verified the feasibility of hot hole flanging process and provided an important reference for virtual production. Keywords: Connection Tube Thermal Hole Flanging Thick-wall Head Pro-hole Diameter Space Ratio Scaled Experiment

Abstract: As-cast 30Cr2Ni4MoV steel was researched quantificationally to obtain the distribution and pattern of the microcosmic defect. By means of finite element simulation and experiment research, porosity consolidating and relative density evolution of as-cast 30Cr2Ni4MoV steel were investigated for a FM stretching process at a constant strain rate 0.001s-1. The studied parameters included three temperatures (800°C, 1000°C, 1250°C) and three deforming passes(1,2,3) and three friction factors(0.3,0.5,0.7), which bracketed the parameters that were used during most primary break-down processes. Temperature had an obvious effect on the porosity consolidating, but friction factor had no effect on the ultimate soundness nearly. When beginning temperature was 1250°C and heat exchanged considered, initial porosity can be eliminated after the accumulated effective strain reached 1.0 at least. The residual defect of the wrought material at different strain lever was compared to the initial defect of as-cast material and found to be somewhat reduced. The impact toughness of the wrought material at different strain lever was also compared to the as-cast material and found to be obvious improved. The difference in these behaviors between as-cast and wrought material could be attributed to the healing of the porosity defect and the enhancement of the soundness at a certain extent.

Abstract: Three-dimension rigid-plastic finite element software, DEFORM-3D, was used to simulate the integral forming processing of a lager thick-wall semi-sphere head with supporting tables. Influencing factors of integral forming, such as initial blank shape, radius of corner at the bottom of the protrusions and the preforming mode etc, were researched quantitatively. A double layer frustum cone blank was determined, which can reduce the variable amplitude of the wall thickness and cause a uniform wall thickness distribution. When radius of corner at the bottom of the protrusions of the machined blank was in 100~130mm, no crack occurred at the bottom of the any supporting tables and a rational size can be obtained after forming. Using mode C (two banding protrusions) to forging the blank for machining can prevent the center metal from thinning and reduce additional tensile stress. Based on the simulation research, the 1:3 scale experiment was done in 31.5MN hydraulic press and the test piece was measured. The result shows that the error between simulation data and test data is less than 5%, which verified the feasibility of integral forming and provided an important reference for virtual production.