The liner of a CNG pressure vessel is manufactured by a DDI(deep drawing and ironing)process for the cylinder part,which is a continuous process that includes a drawing process to reduce the diameter of the billet and...The liner of a CNG pressure vessel is manufactured by a DDI(deep drawing and ironing)process for the cylinder part,which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet.A tractrix die used in the 1^(st) deep drawing allows the blank to flow smoothly by decreasing the punch load and radial tensile stress occurring in the workpiece.It also increases the draw ratio compared to conventional dies,but it causes forming defects.In this study,a shape coefficient(S_(c))is proposed for the tractrix die using the blank diameter(D_(0)),inflow diameter of the workpiece(d_(i)),and inflow angle of the workpiece(θ)for design of the tractrix die.The effects of the thickness and inflow angle of the workpiece on wrinkling and folding were investigated through FEA.Also,a discriminant is proposed for the relative radial stress(σ)generated during the deep drawing process using the tractirx die and used to predict fracture.Based on the results,the blank thickness,the draw ratio,and the inflow of the workpiece angle in the 1^(st) deep drawing process are suggested,and the number of operations in the DDI process was reduced from 6 to 4.This improves the productivity and reduces the manufacturing cost.展开更多
The strips U deep drawing experiments were carried out to study the effect of die cavity dimension with an extension machine manufactured by SANS company. The effects of parameters were analyzed in deep drawing proces...The strips U deep drawing experiments were carried out to study the effect of die cavity dimension with an extension machine manufactured by SANS company. The effects of parameters were analyzed in deep drawing process under different experimental conditions, such as punch load, reduction of thickness, angle of U part and surface quality. The experiment results show that the punch load increases with the decrease of female radius, and larger blank holder force enlarges the range of increasing. With the increasing of blank holder force, the angle of U part increases, and the reduction of foil thickness at the corner becomes larger. Obvious scratch and accumulation at the die cavity corner were observed by SEM. The investigation results indicate that micro U deep drawing of foil is affected by micro die cavity dimension.展开更多
This paper covers the role of anisotropy,temperature,and strain rate on the flow behavior of the material when a conical die is used instead of conventional blank holder.The effect of anisotropy was investigated using...This paper covers the role of anisotropy,temperature,and strain rate on the flow behavior of the material when a conical die is used instead of conventional blank holder.The effect of anisotropy was investigated using Lankford’s coefficient(r)in three directions(0°,45°,and 90°).The effect of working temperatures(Room temperature,100°C-300°C)on drawing stress and strain rate sensitivity on punch pressure were also investigated in detail.ANSYS APDL was used to investigate the effects of temperature,strain rate and anisotropy.The simulation results have confirmed that the strain variation in the direction of r0 and r45 are more than the variation of r90.展开更多
基金Supported by a 2-Year Research Grant of Pusan National University,Korea。
文摘The liner of a CNG pressure vessel is manufactured by a DDI(deep drawing and ironing)process for the cylinder part,which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet.A tractrix die used in the 1^(st) deep drawing allows the blank to flow smoothly by decreasing the punch load and radial tensile stress occurring in the workpiece.It also increases the draw ratio compared to conventional dies,but it causes forming defects.In this study,a shape coefficient(S_(c))is proposed for the tractrix die using the blank diameter(D_(0)),inflow diameter of the workpiece(d_(i)),and inflow angle of the workpiece(θ)for design of the tractrix die.The effects of the thickness and inflow angle of the workpiece on wrinkling and folding were investigated through FEA.Also,a discriminant is proposed for the relative radial stress(σ)generated during the deep drawing process using the tractirx die and used to predict fracture.Based on the results,the blank thickness,the draw ratio,and the inflow of the workpiece angle in the 1^(st) deep drawing process are suggested,and the number of operations in the DDI process was reduced from 6 to 4.This improves the productivity and reduces the manufacturing cost.
基金Projects(50835002 50805035) supported by the National Natural Science Foundation of ChinaProject(2008RFQXG041) supported by the Foundation for Innovation Scholars of Harbin, China
文摘The strips U deep drawing experiments were carried out to study the effect of die cavity dimension with an extension machine manufactured by SANS company. The effects of parameters were analyzed in deep drawing process under different experimental conditions, such as punch load, reduction of thickness, angle of U part and surface quality. The experiment results show that the punch load increases with the decrease of female radius, and larger blank holder force enlarges the range of increasing. With the increasing of blank holder force, the angle of U part increases, and the reduction of foil thickness at the corner becomes larger. Obvious scratch and accumulation at the die cavity corner were observed by SEM. The investigation results indicate that micro U deep drawing of foil is affected by micro die cavity dimension.
文摘This paper covers the role of anisotropy,temperature,and strain rate on the flow behavior of the material when a conical die is used instead of conventional blank holder.The effect of anisotropy was investigated using Lankford’s coefficient(r)in three directions(0°,45°,and 90°).The effect of working temperatures(Room temperature,100°C-300°C)on drawing stress and strain rate sensitivity on punch pressure were also investigated in detail.ANSYS APDL was used to investigate the effects of temperature,strain rate and anisotropy.The simulation results have confirmed that the strain variation in the direction of r0 and r45 are more than the variation of r90.
