Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been ...Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is stili unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the vvorking angle, the axial feeding rate, and the acceptable vvorking course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the bail diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.展开更多
As a successive and local plastic deformation process, backward ball spinning was applied for the purpose of prodacing thin-walled tubular parts with longitudinal inner ribs. According to the local plastic deformation...As a successive and local plastic deformation process, backward ball spinning was applied for the purpose of prodacing thin-walled tubular parts with longitudinal inner ribs. According to the local plastic deformation theoo,, the application of yield criterion to the spinning process and the influence of the radial spinning force component on the formability of inner ribs were analyzed. Based on yield criterion and plastic mechanics, the stable flow rule of metal material and forming criteria of the inner ribs were obtained aad conformed to the experimental results so as to contribute greatly to improving the ball spinning process and optimizing the process variables, such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank, which have a significant influenee on the formability of the inner ribs. The knowledge of the influence of the process variables such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank on the spinning process is essential to preventing the quality defects of the spun parts and obtaining the desired spun parts.展开更多
Melt spinning （MS） and ball milling （BM） were employed to fabricate YMg11Ni alloy, and their structures and hydrogen storage performances were examined. The results reveal that the as-spun and as-milled alloys bot...Melt spinning （MS） and ball milling （BM） were employed to fabricate YMg11Ni alloy, and their structures and hydrogen storage performances were examined. The results reveal that the as-spun and as-milled alloys both exhibit the nanocrystalline and amorphous structure. The as-milled alloy shows a larger hydrogen absorption capacity as compared with the as-spun alloy. More than that, the as-milled alloy exhibits lower onset hydrogen desorption temperature than the as-spun one, which are 549.8 and 560.9 K, respectively. Additionally, the as-milled alloy shows a superior hydrogen desorption property to the as-spun one. On the basis of the time needed by desorbing hydrogen of 3 wt% H2, for the as- milled alloy, it needs 1106, 456, 343, and 180 s corresponding to hydrogen desorption temperatures of 593, 613, 633, and 653 K. However, for the as-spun alloy, the time needed is greater than 2928, 842, 356, and 197 s corresponding to the same temperatures. Hydrogen desorption activation energies of as-milled and as-spun alloys are 98.01 and 105.49 kJ/mol, respectively, which is responsible for that the as-milled alloy possesses a much faster dehydriding rate. By means of the measurement of pressure-composition-temperature （P-C-T） curves, the dehydrogenation enthalpy change of the alloys prepared by MS （△Hoe（MS）） and BM （△Hdc（BM）） is 81.84 and 79.46 kJ/mol, respectively, viz. △Hde（MS） 〉 △Hoc（BM）.展开更多
We consider the impact of drag force and the Magnus effect on the motion of a baseball. Quantitatively we show how the speed-dependent drag coefficient alters the trajectory of the ball. For the Magnus effect we envis...We consider the impact of drag force and the Magnus effect on the motion of a baseball. Quantitatively we show how the speed-dependent drag coefficient alters the trajectory of the ball. For the Magnus effect we envision a scenario where the rotation of the ball confines the Magnus force to the vertical plane;gravity, drag force and the Magnus force make a trio-planar system. We investigate the interplay of these forces on the trajectories.展开更多
As a special method of manufacturing thin wall tubes, the ball spinning process has been used for nearly 30 years because of its less investment of equipment, higher precision, and more perfect properties of products....As a special method of manufacturing thin wall tubes, the ball spinning process has been used for nearly 30 years because of its less investment of equipment, higher precision, and more perfect properties of products. However, the application is limited since the process parameters are determined based on empirical data and laboratory experiments for lack of a whole theoretical analysis. In this paper, some basic parameters such as the force and power parameters have been studied based on an analysis of geometry and mechanics of the process. The calculation of forming forces and the selection of the working angle are carried out. At the end, a perfect comparison between the results of the experiments and the theoretical analysis is made.展开更多
Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain proble...Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.展开更多
文摘Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is stili unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the vvorking angle, the axial feeding rate, and the acceptable vvorking course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the bail diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.
基金Funded by the Overseas Returnee Foundation of HeilongjiangProvince (lc01c13)
文摘As a successive and local plastic deformation process, backward ball spinning was applied for the purpose of prodacing thin-walled tubular parts with longitudinal inner ribs. According to the local plastic deformation theoo,, the application of yield criterion to the spinning process and the influence of the radial spinning force component on the formability of inner ribs were analyzed. Based on yield criterion and plastic mechanics, the stable flow rule of metal material and forming criteria of the inner ribs were obtained aad conformed to the experimental results so as to contribute greatly to improving the ball spinning process and optimizing the process variables, such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank, which have a significant influenee on the formability of the inner ribs. The knowledge of the influence of the process variables such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank on the spinning process is essential to preventing the quality defects of the spun parts and obtaining the desired spun parts.
基金financially supported by the National Natural Science Foundations of China(Nos.51371094 and 51471054)the Natural Science Foundation of Inner Mongolia,China(No.2015MS0558)
文摘Melt spinning （MS） and ball milling （BM） were employed to fabricate YMg11Ni alloy, and their structures and hydrogen storage performances were examined. The results reveal that the as-spun and as-milled alloys both exhibit the nanocrystalline and amorphous structure. The as-milled alloy shows a larger hydrogen absorption capacity as compared with the as-spun alloy. More than that, the as-milled alloy exhibits lower onset hydrogen desorption temperature than the as-spun one, which are 549.8 and 560.9 K, respectively. Additionally, the as-milled alloy shows a superior hydrogen desorption property to the as-spun one. On the basis of the time needed by desorbing hydrogen of 3 wt% H2, for the as- milled alloy, it needs 1106, 456, 343, and 180 s corresponding to hydrogen desorption temperatures of 593, 613, 633, and 653 K. However, for the as-spun alloy, the time needed is greater than 2928, 842, 356, and 197 s corresponding to the same temperatures. Hydrogen desorption activation energies of as-milled and as-spun alloys are 98.01 and 105.49 kJ/mol, respectively, which is responsible for that the as-milled alloy possesses a much faster dehydriding rate. By means of the measurement of pressure-composition-temperature （P-C-T） curves, the dehydrogenation enthalpy change of the alloys prepared by MS （△Hoe（MS）） and BM （△Hdc（BM）） is 81.84 and 79.46 kJ/mol, respectively, viz. △Hde（MS） 〉 △Hoc（BM）.
文摘We consider the impact of drag force and the Magnus effect on the motion of a baseball. Quantitatively we show how the speed-dependent drag coefficient alters the trajectory of the ball. For the Magnus effect we envision a scenario where the rotation of the ball confines the Magnus force to the vertical plane;gravity, drag force and the Magnus force make a trio-planar system. We investigate the interplay of these forces on the trajectories.
文摘As a special method of manufacturing thin wall tubes, the ball spinning process has been used for nearly 30 years because of its less investment of equipment, higher precision, and more perfect properties of products. However, the application is limited since the process parameters are determined based on empirical data and laboratory experiments for lack of a whole theoretical analysis. In this paper, some basic parameters such as the force and power parameters have been studied based on an analysis of geometry and mechanics of the process. The calculation of forming forces and the selection of the working angle are carried out. At the end, a perfect comparison between the results of the experiments and the theoretical analysis is made.
基金supported by Overseas Returnee Foundation of Heilongjiang Province, China (lc01c13).
文摘Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.
