To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators suc...To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.展开更多
Being the largest comprehensive urban development project in the city of Harbin, theremolding of the north outer ring road not only improved the city’s road condition, but al-so brought along the initiatives to redev...Being the largest comprehensive urban development project in the city of Harbin, theremolding of the north outer ring road not only improved the city’s road condition, but al-so brought along the initiatives to redevelop the large number of dilapidated sheds alongthe road, transform industrial technoloqy and advance environment quality.展开更多
In this article. the programme of Nanjing’s Outer ring road planning. and the investiga-tion. analysis and forecast of the volume of this section’s traffic are discussed; the corre-sponding construction and technica...In this article. the programme of Nanjing’s Outer ring road planning. and the investiga-tion. analysis and forecast of the volume of this section’s traffic are discussed; the corre-sponding construction and technical indices put forward; and the economic analysis ofthe implementation of the mentioned programme carried out.展开更多
Semi-floating ring bearing（SFRB） is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the d...Semi-floating ring bearing（SFRB） is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the design of turbocharger. In order to explore the effects of outer clearance, a transient finite element analysis program for rotor and oil film bearing is built and validated by a published experimental case. The nonlinear dynamic behaviors ofrotor-SFRB system are simulated. According to the simulation results, two representative subsynchronous oscillations excited by the two hearings respectively are discovered. As the outer clearance of SFRB increases from 24 ~tm to 60 pro, the low-frequency subsynchronous oscillation experiences three steps, including a strong start, a gradual recession and a combination with the other one. At the same time, the high-frequency subsynchronous oscillation starts to appear gradually, then strengthens, and finally combines. If gravity and unbalance are neglected, the combination will start starts from high rotor speed and extents to low rotor speed, just like a ＂zipper＂. It is found from the quantitative analysis that when the outer clearance increases, the vibration amplitude experiences large value firstly, then reduction, and suddenly increasing after combination. A useful design principle of SFRB outer clearance for minimum vibration amplitude is proposed： the outer clearance value should be chosen to keep the frequency of two subsynchronous oscillations clearly separated and their amplitudes close.展开更多
基金supported by the China Postdoctoral Science Foundation(Grant No.2022M721395)the National Natural Science Foundation of China(Grant No.72072089).
文摘To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.
文摘Being the largest comprehensive urban development project in the city of Harbin, theremolding of the north outer ring road not only improved the city’s road condition, but al-so brought along the initiatives to redevelop the large number of dilapidated sheds alongthe road, transform industrial technoloqy and advance environment quality.
文摘In this article. the programme of Nanjing’s Outer ring road planning. and the investiga-tion. analysis and forecast of the volume of this section’s traffic are discussed; the corre-sponding construction and technical indices put forward; and the economic analysis ofthe implementation of the mentioned programme carried out.
基金Supported by National Natural Science Foundation of China(Grant No51506108)
文摘Semi-floating ring bearing（SFRB） is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the design of turbocharger. In order to explore the effects of outer clearance, a transient finite element analysis program for rotor and oil film bearing is built and validated by a published experimental case. The nonlinear dynamic behaviors ofrotor-SFRB system are simulated. According to the simulation results, two representative subsynchronous oscillations excited by the two hearings respectively are discovered. As the outer clearance of SFRB increases from 24 ~tm to 60 pro, the low-frequency subsynchronous oscillation experiences three steps, including a strong start, a gradual recession and a combination with the other one. At the same time, the high-frequency subsynchronous oscillation starts to appear gradually, then strengthens, and finally combines. If gravity and unbalance are neglected, the combination will start starts from high rotor speed and extents to low rotor speed, just like a ＂zipper＂. It is found from the quantitative analysis that when the outer clearance increases, the vibration amplitude experiences large value firstly, then reduction, and suddenly increasing after combination. A useful design principle of SFRB outer clearance for minimum vibration amplitude is proposed： the outer clearance value should be chosen to keep the frequency of two subsynchronous oscillations clearly separated and their amplitudes close.
