A process parameter optimization method for mold wear during die forging process is proposed and a mold life prediction method based on polynomial fitting is presented,by combining the variance analysis method in the ...A process parameter optimization method for mold wear during die forging process is proposed and a mold life prediction method based on polynomial fitting is presented,by combining the variance analysis method in the orthogonal test with the finite element simulation test in the forging process.The process parameters with the greatest influence on the mold wear during the die forging process and the optimal solution of the process parameters to minimize the wear depth of the mold are derived.The hot die forging process is taken as an example,and a mold wear correction model for hot forging processes is derived based on the Archard wear model.Finite element simulation analysis of die wear process in hot die forging based on deform software is performed to study the relationship between the wear depth of the mold working surface and the die forging process parameters during hot forging process.The optimized process parameters suitable for hot forging are derived by orthogonal experimental design and analysis of variance.The average wear amount of the mold during the die forging process is derived by calculating the wear depth of a plurality of key nodes on the mold surface.Mold life for the entire production process is predicted based on average mold wear depth and polynomial fitting.展开更多
Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular p...Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular porthole die to produce hollow rectangle sections which are widely used in construction. The upper die was mainly studied. Because it is symmetrical, a quarter of the die was analyzed. The upper die was divided into 2199 elements with 3018 nodes. Elements were produced by four steps and the geometric shape of the die could be well simulated. The boundary condition was given according to the shape of the welding chamber and an empirical average extrusion stress was adopted, which was 210N/mm 2. Three-dimensional equivalent stresses were received. The original porthole die studied had obvious stress concentration and the stress distribution was very inhomogeneous, which would heavily affect the die life. A new design was proposed in which the portholes were rearranged and their shape and dimension were changed. According to the finite element analysis, the stress distribution of the improved die was quite homogeneous and the stress concentration was lessened.展开更多
Fatigue failure is a main failure mode for magnesium and other alloys. It is beneficial for fatigue design and fatigue life improvement to investigate the low cycle fatigue behavior of magnesium alloys. In order to in...Fatigue failure is a main failure mode for magnesium and other alloys. It is beneficial for fatigue design and fatigue life improvement to investigate the low cycle fatigue behavior of magnesium alloys. In order to investigate the low cycle fatigue behavior of die cast Mg-AI-Mn-Ce magnesium alloy, the strain controlled fatigue experiments were performed at room temperature and fatigue fracture surfaces of specimens were observed with scanning election microscopy for the alloys under die-cast and aged states. Cyclic stress response curves, strain amplitude versus reversals to failure curve, total strain amplitude versus fatigue life curves and cyclic stress-strain curves of Mg-AI-Mn-Ce alloys were analyzed. The results show that the Mg-AI-Mn-Ce alloys under die-cast （F） and aged （T5） states exhibit cyclic strain hardening under the applied total strain amplitudes, and aging treatment could greatly increase the cyclic stress amplitudes of die cast Mg-AI-Mn-Ce alloys. The relationships between the plastic strain amplitude, the elastic strain amplitude and reversals to failure of Mg-AI-Mn-Ce magnesium alloy under different treatment states could be described by Coffin-Manson and Basquin equations, respectively. Observations on the fatigue fracture surface of specimens reveal that the fatigue cracks initiate on the surface of specimens and propagate transgranularly.展开更多
Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg ...Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg alloys at room temperature was investigated. The experimental results show that both permanent mold cast and die-cast AI-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening. At the same total strain amplitude, the diecast AI-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast AI-Si-Cu-Mg alloy. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively.展开更多
基金This work was supported in part by the National Natural Science Foundation of China(No.51575008).
文摘A process parameter optimization method for mold wear during die forging process is proposed and a mold life prediction method based on polynomial fitting is presented,by combining the variance analysis method in the orthogonal test with the finite element simulation test in the forging process.The process parameters with the greatest influence on the mold wear during the die forging process and the optimal solution of the process parameters to minimize the wear depth of the mold are derived.The hot die forging process is taken as an example,and a mold wear correction model for hot forging processes is derived based on the Archard wear model.Finite element simulation analysis of die wear process in hot die forging based on deform software is performed to study the relationship between the wear depth of the mold working surface and the die forging process parameters during hot forging process.The optimized process parameters suitable for hot forging are derived by orthogonal experimental design and analysis of variance.The average wear amount of the mold during the die forging process is derived by calculating the wear depth of a plurality of key nodes on the mold surface.Mold life for the entire production process is predicted based on average mold wear depth and polynomial fitting.
文摘Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular porthole die to produce hollow rectangle sections which are widely used in construction. The upper die was mainly studied. Because it is symmetrical, a quarter of the die was analyzed. The upper die was divided into 2199 elements with 3018 nodes. Elements were produced by four steps and the geometric shape of the die could be well simulated. The boundary condition was given according to the shape of the welding chamber and an empirical average extrusion stress was adopted, which was 210N/mm 2. Three-dimensional equivalent stresses were received. The original porthole die studied had obvious stress concentration and the stress distribution was very inhomogeneous, which would heavily affect the die life. A new design was proposed in which the portholes were rearranged and their shape and dimension were changed. According to the finite element analysis, the stress distribution of the improved die was quite homogeneous and the stress concentration was lessened.
基金financially supported by the Science and Technology Research Project of Liaoning Province Education Department(L2012038)
文摘Fatigue failure is a main failure mode for magnesium and other alloys. It is beneficial for fatigue design and fatigue life improvement to investigate the low cycle fatigue behavior of magnesium alloys. In order to investigate the low cycle fatigue behavior of die cast Mg-AI-Mn-Ce magnesium alloy, the strain controlled fatigue experiments were performed at room temperature and fatigue fracture surfaces of specimens were observed with scanning election microscopy for the alloys under die-cast and aged states. Cyclic stress response curves, strain amplitude versus reversals to failure curve, total strain amplitude versus fatigue life curves and cyclic stress-strain curves of Mg-AI-Mn-Ce alloys were analyzed. The results show that the Mg-AI-Mn-Ce alloys under die-cast （F） and aged （T5） states exhibit cyclic strain hardening under the applied total strain amplitudes, and aging treatment could greatly increase the cyclic stress amplitudes of die cast Mg-AI-Mn-Ce alloys. The relationships between the plastic strain amplitude, the elastic strain amplitude and reversals to failure of Mg-AI-Mn-Ce magnesium alloy under different treatment states could be described by Coffin-Manson and Basquin equations, respectively. Observations on the fatigue fracture surface of specimens reveal that the fatigue cracks initiate on the surface of specimens and propagate transgranularly.
文摘Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg alloys at room temperature was investigated. The experimental results show that both permanent mold cast and die-cast AI-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening. At the same total strain amplitude, the diecast AI-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast AI-Si-Cu-Mg alloy. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively.
