To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a ...To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a case study of the cam contour optimization for an offset press open-close gripper mechanism.The acceleration curve and the residual vibration model of the follower were separately studied.A symmetric harmonic trapezoidal curve was designed to control the follower’s acceleration,and single-DOF lumped parameter torsional vibration model was proposed to describe the follower’s residual vibration.Accordingly,corresponding motion curve design software and Simulink vibration model of the follower were developed respectively,and they were integrated into an automatic optimization platform with iSIGHT.The multi-objective optimization with objectives of minimizing both the acceleration and the residual vibration of the follower was completed within the platform by using NSGA-II algorithm.An appropriate point with lower acceleration and residual vibration was chosen from Pareto front as an optimal solution of the follower’s motion curve.Based on the follower’s new motion curve,the actual cam contour was generated by inverse kinematic simulation in COSMOSMotion.The offset press that installed our new designed cam exhibited a lower vibration than the previous machine,and the maximum measured acceleration of the offset press at a printing speed of 15000 r/h is reduced by 7.7%.展开更多
Press hardened steel(PHS)plays a key role in the manufacture of anti-collision structural components.The formation of δ-ferrite is a suffering issue for the laser welding of Al-Si coated PHS.Oscillating laser was use...Press hardened steel(PHS)plays a key role in the manufacture of anti-collision structural components.The formation of δ-ferrite is a suffering issue for the laser welding of Al-Si coated PHS.Oscillating laser was used to weld Al-Si coated 1.5 GPa PHS and novel 2 GPa PHS,and the effect of laser offset on the microstructure and properties of the dissimilar welded joints was studied.The results showed that a perfect weld profile was achieved by laser offset welding(LOW),without any welding defects.The δ-ferrite formed in as-received welds of laser alignment welding(LAW)with high Al content(up to 2.9 wt.%),but it disappeared with the laser offset to 2 GPa PHS,and the maximum Al content in the segregation zone reduced to 1.2 wt.%.After post-welding heat treatment,the δ-ferrite was coarsened and theα-ferrite formed in the secondary Al-rich area for the high Ac3 temperature,but the α-ferrite was few and fine in LOW welds.The hardness in the LAW welds was lower than that in the LOW welds,due to the presence of δ-ferrite,as well as less carbon content and Ti and V alloying elements.The tensile strength(1561 MPa)and elongation(5.4%)with LOW were higher than those with LAW(1490 MPa,3.1%),and the fracture occurred in the Al-Si coated PHS.It is indicated that adjusting the laser offset is effective to prevent the formation of δ-ferrite and is potential to avoid the formation of α-ferrite.It also provides a wide heat treatment temperature window for the dissimilar welds of 1.5 GPa PHS and novel 2 GPa PHS.展开更多
Publisher Correction to:Journal of Science in Sport and Exercise https://doi.org/10.1007/s42978-022-00200-1 In this article,Charlie Ottinger,Raad Gheith,Matthew Ste-fan,Ryan Lowery,and Jacob Wilson at Research Divisio...Publisher Correction to:Journal of Science in Sport and Exercise https://doi.org/10.1007/s42978-022-00200-1 In this article,Charlie Ottinger,Raad Gheith,Matthew Ste-fan,Ryan Lowery,and Jacob Wilson at Research Division,Applied Science and Performance Institute;and Salvatore LoDuca at Offset Ventures LLC were missing from the author list.展开更多
基金the Foshan Science and Technology Innovation Team Project(No.FS0AA-KJ919-4402-0060)the National Natural Science Foundation of China(No.62263018)。
文摘To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a case study of the cam contour optimization for an offset press open-close gripper mechanism.The acceleration curve and the residual vibration model of the follower were separately studied.A symmetric harmonic trapezoidal curve was designed to control the follower’s acceleration,and single-DOF lumped parameter torsional vibration model was proposed to describe the follower’s residual vibration.Accordingly,corresponding motion curve design software and Simulink vibration model of the follower were developed respectively,and they were integrated into an automatic optimization platform with iSIGHT.The multi-objective optimization with objectives of minimizing both the acceleration and the residual vibration of the follower was completed within the platform by using NSGA-II algorithm.An appropriate point with lower acceleration and residual vibration was chosen from Pareto front as an optimal solution of the follower’s motion curve.Based on the follower’s new motion curve,the actual cam contour was generated by inverse kinematic simulation in COSMOSMotion.The offset press that installed our new designed cam exhibited a lower vibration than the previous machine,and the maximum measured acceleration of the offset press at a printing speed of 15000 r/h is reduced by 7.7%.
基金financially supported by the funds of the National Natural Science Foundation of China(Nos.52005357 and U1908224)the support of Postdoctoral Research Foundation of China(2022M712308)Liaoning Revitalization Talents Program(No.XLYC2007066).
文摘Press hardened steel(PHS)plays a key role in the manufacture of anti-collision structural components.The formation of δ-ferrite is a suffering issue for the laser welding of Al-Si coated PHS.Oscillating laser was used to weld Al-Si coated 1.5 GPa PHS and novel 2 GPa PHS,and the effect of laser offset on the microstructure and properties of the dissimilar welded joints was studied.The results showed that a perfect weld profile was achieved by laser offset welding(LOW),without any welding defects.The δ-ferrite formed in as-received welds of laser alignment welding(LAW)with high Al content(up to 2.9 wt.%),but it disappeared with the laser offset to 2 GPa PHS,and the maximum Al content in the segregation zone reduced to 1.2 wt.%.After post-welding heat treatment,the δ-ferrite was coarsened and theα-ferrite formed in the secondary Al-rich area for the high Ac3 temperature,but the α-ferrite was few and fine in LOW welds.The hardness in the LAW welds was lower than that in the LOW welds,due to the presence of δ-ferrite,as well as less carbon content and Ti and V alloying elements.The tensile strength(1561 MPa)and elongation(5.4%)with LOW were higher than those with LAW(1490 MPa,3.1%),and the fracture occurred in the Al-Si coated PHS.It is indicated that adjusting the laser offset is effective to prevent the formation of δ-ferrite and is potential to avoid the formation of α-ferrite.It also provides a wide heat treatment temperature window for the dissimilar welds of 1.5 GPa PHS and novel 2 GPa PHS.
文摘Publisher Correction to:Journal of Science in Sport and Exercise https://doi.org/10.1007/s42978-022-00200-1 In this article,Charlie Ottinger,Raad Gheith,Matthew Ste-fan,Ryan Lowery,and Jacob Wilson at Research Division,Applied Science and Performance Institute;and Salvatore LoDuca at Offset Ventures LLC were missing from the author list.
