In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertic...In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertical cross-section. According to the latest developing theory and potential of cold pressure forming： combination of pressure and cold forging, a new flow control forming of sheet metal（FCF） is excogitated based on blanking process of general stamping and combined with cold forging processes such as extrusion and coining, etc, which is aiming at the above-mentioned new type of sheet metal part. With utilization of this new process, the new type of sheet metal parts can be manufactured. In order to shorten the testing period, the numerical simulation was carried out by using DEFORM-3D software, and both deformation and mechanics rules were analyzed. Based on the simulation, both punching part and blanked parts of this new type were successfully developed. Then a new conception of optimal distance between the step walls of inner hole and outside edge was proposed and the design principle for its numerical value was inferred. Furthermore, a mold set for combination of stamping ＆ cold forging was designed and manufactured, by which the technologic experiments were taken for validation with Aluminum plate of thickness 2.35 mm for power battery cover board, which verified the principle of the distance between the step walls. The research of cold pressure forming of thin sheet metal with step cross-section is significant, not only to the development of modem mechanical manufacture, but also to metal plastic forming science.展开更多
For the section coupled system of multilayer dynamics of fluids in porous media, a parallel scheme modified by the characteristic finite difference fractional steps is proposed for a complete point set consisting of c...For the section coupled system of multilayer dynamics of fluids in porous media, a parallel scheme modified by the characteristic finite difference fractional steps is proposed for a complete point set consisting of coarse and fine partitions. Some tech- niques, such as calculus of variations, energy method, twofold-quadratic interpolation of product type, multiplicative commutation law of difference operators, decomposition of high order difference operators, and prior estimates, are used in theoretical analysis. Optimal order estimates in 12 norm are derived to show accuracy of the second order approximation solutions. These methods have been used to simulate the problems of migration-accumulation of oil resources.展开更多
Ⅰ.根据句意、首字母提示完成单词。1.Listen!The b________are singing in the tree.2.Students usually c________their classroom after school.3.In the park,many people use(用)their C_________to take photos.
Objective To evaluate the value of MRI diffusion weighted imaging in localization of prostate cancer with whole-mount step section pathology. Methods We treated 36 patients using laparoscopic radical prostatectomy fro...Objective To evaluate the value of MRI diffusion weighted imaging in localization of prostate cancer with whole-mount step section pathology. Methods We treated 36 patients using laparoscopic radical prostatectomy from Oct. 2009 to Jun. 2010. Patients who did not have an MRL /DWI examination or a surgical history of pros-展开更多
Ⅰ.根据句意和首字母完成句子中的单词。1.There are some newspapers and m_______ on the desk in the library.2.Please don’t t_______about the new TV play.We are having class now.3.Mr.Black is a d_______.He works in a
A stepped-section ring consists of two rectangular section rings,a big ring and a small ring,joined together.This kind of ring is difficult to process by the ring rolling technique because of its complex cross-section...A stepped-section ring consists of two rectangular section rings,a big ring and a small ring,joined together.This kind of ring is difficult to process by the ring rolling technique because of its complex cross-sectional shape.Thus a reasonable blank design is necessary.In this paper,four blank designs,one is a rectangular cross-section and the other three are stepped-sections with different step volumes,are proposed and compared with each other using theoretical analysis,FE simulation and experiments.It is shown that three of the designs can lead to volume flow from small ring into big ring during rolling,which is disadvantageous for shape formation and dimensional precision;however,the other design may result in good ring shape and high dimensional precision.Therefore,the optimal blank design is determined to be the one in which the volumes of the big and small rings of the initial blank are equal to those of the final rings,respectively.展开更多
文摘In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertical cross-section. According to the latest developing theory and potential of cold pressure forming： combination of pressure and cold forging, a new flow control forming of sheet metal（FCF） is excogitated based on blanking process of general stamping and combined with cold forging processes such as extrusion and coining, etc, which is aiming at the above-mentioned new type of sheet metal part. With utilization of this new process, the new type of sheet metal parts can be manufactured. In order to shorten the testing period, the numerical simulation was carried out by using DEFORM-3D software, and both deformation and mechanics rules were analyzed. Based on the simulation, both punching part and blanked parts of this new type were successfully developed. Then a new conception of optimal distance between the step walls of inner hole and outside edge was proposed and the design principle for its numerical value was inferred. Furthermore, a mold set for combination of stamping ＆ cold forging was designed and manufactured, by which the technologic experiments were taken for validation with Aluminum plate of thickness 2.35 mm for power battery cover board, which verified the principle of the distance between the step walls. The research of cold pressure forming of thin sheet metal with step cross-section is significant, not only to the development of modem mechanical manufacture, but also to metal plastic forming science.
基金supported by the Major State Basic Research Program of China(No.19990328)the National Tackling Key Program(No.20050200069)+1 种基金the National Natural Science Foundation of China(Nos.10372052,10771124,11101244,and 11271231)the Doctorate Foundation of the State Education Commission(No.20030422047)
文摘For the section coupled system of multilayer dynamics of fluids in porous media, a parallel scheme modified by the characteristic finite difference fractional steps is proposed for a complete point set consisting of coarse and fine partitions. Some tech- niques, such as calculus of variations, energy method, twofold-quadratic interpolation of product type, multiplicative commutation law of difference operators, decomposition of high order difference operators, and prior estimates, are used in theoretical analysis. Optimal order estimates in 12 norm are derived to show accuracy of the second order approximation solutions. These methods have been used to simulate the problems of migration-accumulation of oil resources.
文摘Ⅰ.根据句意、首字母提示完成单词。1.Listen!The b________are singing in the tree.2.Students usually c________their classroom after school.3.In the park,many people use(用)their C_________to take photos.
文摘Objective To evaluate the value of MRI diffusion weighted imaging in localization of prostate cancer with whole-mount step section pathology. Methods We treated 36 patients using laparoscopic radical prostatectomy from Oct. 2009 to Jun. 2010. Patients who did not have an MRL /DWI examination or a surgical history of pros-
文摘Ⅰ.根据句意和首字母完成句子中的单词。1.There are some newspapers and m_______ on the desk in the library.2.Please don’t t_______about the new TV play.We are having class now.3.Mr.Black is a d_______.He works in a
基金Supported by the Project of National Natural Science Foundation of China (Grant No.50675164)the Natural Science Foundation of China for Distinguished Young Scholars (Grant No.50725517)
文摘A stepped-section ring consists of two rectangular section rings,a big ring and a small ring,joined together.This kind of ring is difficult to process by the ring rolling technique because of its complex cross-sectional shape.Thus a reasonable blank design is necessary.In this paper,four blank designs,one is a rectangular cross-section and the other three are stepped-sections with different step volumes,are proposed and compared with each other using theoretical analysis,FE simulation and experiments.It is shown that three of the designs can lead to volume flow from small ring into big ring during rolling,which is disadvantageous for shape formation and dimensional precision;however,the other design may result in good ring shape and high dimensional precision.Therefore,the optimal blank design is determined to be the one in which the volumes of the big and small rings of the initial blank are equal to those of the final rings,respectively.
