With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned st...With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.展开更多
According to the revised Cailikefu＇s rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus success...According to the revised Cailikefu＇s rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus successfully established for 2 800 mm heavy shear of some iron and steel company. Shear and bar forces of steel plate, before and after the adoption of negative offset structure, were analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. It was found that the back-wall push force keeps large even at the time that the maximum rolling shear was obtained; meanwhile, back-wall push force is the most approximate to side forces when 60--100 mm of offset was adopted. Both theoretical results and onsite shear quality show that the negative offset plays an important role in ensuring the stability of pure rolling shear and keeping blade clearance constant.展开更多
With rollers as elastic bodies and workpieces as elastoplastic bodies,the rolling problem can be viewed as a friction elastic-plastic contact problem.With fewer assumptions in the simulation of strip-rolling process,a...With rollers as elastic bodies and workpieces as elastoplastic bodies,the rolling problem can be viewed as a friction elastic-plastic contact problem.With fewer assumptions in the simulation of strip-rolling process,a boundary element method（BEM）for two-dimensional elastoplastic finite strain and finite deformation analysis of contact problems with friction was presented.All the equations for contact problems,which include multi-nonlinearities,were obtained.Incremental and iterative procedures were used to find contact pressure and friction stress.Moreover,initial strain rate algorithm and work-hardening material behavior can be assumed in the plastic analysis.Several examples were presented,and the results of contact pressure and friction stress were in excellent agreement with those of analysis.展开更多
基金Item Sponsored by National Natural Science Foundation of China (50575155)
文摘With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.
基金Item Sponsored by National Natural Science Foundation of China (50575155)National Tenth-Five Key Technologies Research and Development Program(ZZ01-13A-03-03-04)Shanxi Provincial Key Technologies Research and Development Program of China (2006031174)
文摘According to the revised Cailikefu＇s rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus successfully established for 2 800 mm heavy shear of some iron and steel company. Shear and bar forces of steel plate, before and after the adoption of negative offset structure, were analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. It was found that the back-wall push force keeps large even at the time that the maximum rolling shear was obtained; meanwhile, back-wall push force is the most approximate to side forces when 60--100 mm of offset was adopted. Both theoretical results and onsite shear quality show that the negative offset plays an important role in ensuring the stability of pure rolling shear and keeping blade clearance constant.
基金Item Sponsored by National Natural Science Foundation of China(50575155)
文摘With rollers as elastic bodies and workpieces as elastoplastic bodies,the rolling problem can be viewed as a friction elastic-plastic contact problem.With fewer assumptions in the simulation of strip-rolling process,a boundary element method（BEM）for two-dimensional elastoplastic finite strain and finite deformation analysis of contact problems with friction was presented.All the equations for contact problems,which include multi-nonlinearities,were obtained.Incremental and iterative procedures were used to find contact pressure and friction stress.Moreover,initial strain rate algorithm and work-hardening material behavior can be assumed in the plastic analysis.Several examples were presented,and the results of contact pressure and friction stress were in excellent agreement with those of analysis.
