Forming Process Research For Combined Fine-Blanking And Extrusion On Sheet Metal Parts With Boss

Fine-blanking technology has many advantages,such as high dimensional accuracy,good quality of blanking surface and low cost(under a certain batch).It is widely used in the processing of three-dimensional fine-blanking parts with boss(plate type).In recent years,the combination of fine-blanking and extrusion forming has been used to manufacture three-dimensional fine-blanking parts with boss.At present,there is still a lack of systematic and further research in terms of combined fine-blanking and extrusion process,mainly in sheet metal extrusion,in order to lay the foundation for practical application of combined fine-blanking and extrusion process,this paper intends to study the mechanism,process and defect problems of combined fine-blanking and extrusion forming on sheet metal parts with boss.This paper started with the characteristic of combined fine-blanking and extrusion forming process,classified the combined process of fine-blanking on sheet metal with extruded boss;The finite element model of combined fine-blanking and extrusion forming on sheet metal parts with boss was established,and this model was used to simulate the forming process by using the finite element software DEFORM-3D.Through the analysis of equivalent stress and strain distribution and metal flow state in the forming process,proved that it is feasible to replace research on extrusion forming on sheet metal with extrusion forming region in combined fine-blanking and extrusion forming,stress and strain distribution and material flow law of extrusion forming region in combined fine-blanking and extrusion forming were obtained by simulating the process of extrusion forming on sheet metal.The forming die of sheet metal with extruded boss was designed,and the experimental scheme was formulated,physical experiments on the 315 T fine-blanking hydraulic press were carried out,the experimental work pieces can be used to directly analyze the forming defects of the extrusion on sheet metal with boss,and the data of load-stroke can verify the accuracy of forming force formula of extrusion on sheet metal with boss.The process of extrusion on sheet metal with cylindrical boss was analyzed,and the forming force formula of extrusion on sheet metal with boss was established by principal stress method,and the theoretical formula was verified through the the data of load-strokeobtained from physical experiments.The possible forming defects in the sheet metal with extruded boss were analyzed.The causes of various defects were analyzed by numerical simulation,and corresponding control measures were put forward for all kinds of defects.Finally,with the combination of finite element simulation and orthogonal test method,the influence factors of process parameters on the forming limit of the boss were analyzed,the selection of the optimal combination of parameters in the orthogonal experiment was obtained;The relationship diagrams between the relative height of the boss at different extrusion ratio and extrusion depth of three typical plastic fine-blanking materials,including 10 hot rolled steel,Q235 B and annealed 45 steel were obtained,which provided the basis for the selection of the forming limit of boss when combined fine-blanking and extrusion forming was designed.Three kinds of sheet metal extrusion die structure were put forward to get greater boss height.All the research results for the combined process of fine-blanking on sheet metal with boss have practical reference and guiding value for fine-blanking production of three-dimensional precision contour parts.