The value of a drawing die＇s cone angle has great influence on wire drawing. In order to determine the optimum value of a drawing die＇ s cone angle, the plastic deformation power Wi, shear deformation power Wi and f...The value of a drawing die＇s cone angle has great influence on wire drawing. In order to determine the optimum value of a drawing die＇ s cone angle, the plastic deformation power Wi, shear deformation power Wi and friction power of contact surface Wf were calculated using the upper bound theory with a reasonable and movement permitted velocity field according to the related characteristics. Then the relation between half cone angle and unit drawing force was obtained and it was compared with the result with the spherical velocity field. The relative error of the two near the optimal value is only about 0. 26% through comparing with existing calculated results. Finally, in an ABAQUS environment the finite element modal of the wire rod with 12. 5 mm diameter in first drawing pass was established and the axial drawing force in different cone angles was obtained using the ABAQUS/Explicit explicit integration method. The finite element method （FEM） results verify the results using the upper bound theory and this indicated that the velocity field and the relation between half cone angle and unit drawing force reasonable.展开更多
Using the upper bound element technique (UBET), a numerical model was proposed for analyzing the metal deformation behavior in the extrusion process of ribbed thin wall pipes through a porthole die. Optimization param...Using the upper bound element technique (UBET), a numerical model was proposed for analyzing the metal deformation behavior in the extrusion process of ribbed thin wall pipes through a porthole die. Optimization parameters were contained in the numerical model and determined through minimizing the total work of metal deformation. Taking the extrusion process of thin wall pipe with one rib as an example, the calculated results using the proposed model are as follows: the extrusion pressure p is linearly related to the extrusion ratio R by p = a+bR 0.683 , where a = 14.13, b = 0.911. When the length of the billet remaining in container is shorter than a quarter of the container diameter, the plastic region extends over the whole of the remained billet and the extrusion process reaches the state of funnel deformation. There exists an optimum depth of welding chamber in respect of the extrusion pressure, and to the calculated example the optimum depth is about 10% of the circumscribed diameter of portholes. To obtain more equitable metal flow in welding chamber, it is required to make the dividing planes in container to be consistent with corresponding welding planes in the chamber ( θ max i = θ′ max i ) through choosing different entering area for each of the portholes.展开更多
The double-die ironing process is studied by means of UBM. The formulas of deformation load.contact stress on die surface, and tensile stress which acts on workpiece is obtained. Taking account of dirnensional accurac...The double-die ironing process is studied by means of UBM. The formulas of deformation load.contact stress on die surface, and tensile stress which acts on workpiece is obtained. Taking account of dirnensional accuracy, a new critical condition of limit reduction in cross section area is put forward for the flrst time. The test experiment indicats that results of theoretical analysis well accord with the actual conditions.[0]展开更多
基金supported by Foundation of Guizhou Science and Technology Department under Grant No.[2008]2210 and No.[2009]3009Foundation of Guizhou University under Grant No. [2007]25
文摘The value of a drawing die＇s cone angle has great influence on wire drawing. In order to determine the optimum value of a drawing die＇ s cone angle, the plastic deformation power Wi, shear deformation power Wi and friction power of contact surface Wf were calculated using the upper bound theory with a reasonable and movement permitted velocity field according to the related characteristics. Then the relation between half cone angle and unit drawing force was obtained and it was compared with the result with the spherical velocity field. The relative error of the two near the optimal value is only about 0. 26% through comparing with existing calculated results. Finally, in an ABAQUS environment the finite element modal of the wire rod with 12. 5 mm diameter in first drawing pass was established and the axial drawing force in different cone angles was obtained using the ABAQUS/Explicit explicit integration method. The finite element method （FEM） results verify the results using the upper bound theory and this indicated that the velocity field and the relation between half cone angle and unit drawing force reasonable.
文摘Using the upper bound element technique (UBET), a numerical model was proposed for analyzing the metal deformation behavior in the extrusion process of ribbed thin wall pipes through a porthole die. Optimization parameters were contained in the numerical model and determined through minimizing the total work of metal deformation. Taking the extrusion process of thin wall pipe with one rib as an example, the calculated results using the proposed model are as follows: the extrusion pressure p is linearly related to the extrusion ratio R by p = a+bR 0.683 , where a = 14.13, b = 0.911. When the length of the billet remaining in container is shorter than a quarter of the container diameter, the plastic region extends over the whole of the remained billet and the extrusion process reaches the state of funnel deformation. There exists an optimum depth of welding chamber in respect of the extrusion pressure, and to the calculated example the optimum depth is about 10% of the circumscribed diameter of portholes. To obtain more equitable metal flow in welding chamber, it is required to make the dividing planes in container to be consistent with corresponding welding planes in the chamber ( θ max i = θ′ max i ) through choosing different entering area for each of the portholes.
文摘The double-die ironing process is studied by means of UBM. The formulas of deformation load.contact stress on die surface, and tensile stress which acts on workpiece is obtained. Taking account of dirnensional accuracy, a new critical condition of limit reduction in cross section area is put forward for the flrst time. The test experiment indicats that results of theoretical analysis well accord with the actual conditions.[0]
