Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission.Many engine components involved with sliding contact are all susceptible to scuffing failure at some...Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission.Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period.Therefore,it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine.Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine.The frictional forces,wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester.The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin.Several coatings on the ring specimen were used,such as DLC,TiN,Cr-ceramic and TiAlN,in order to improve the tribological characteristics of the ring.The coefficients of friction were monitored during the tests,and the wear volumes of the piston ring surfaces with various coatings were compared.Test results show that the DLC coating exhibits better tribological properties than the other coatings.The graphite structure of this coating is responsible for the low friction and wear of the DLC film.The TiN and DLC coatings show better scuffing resistance than the other coatings.The TiN and Cr-ceramic coated rings show good wear resistance and high friction.展开更多
Cold ring rolling is an advanced but complex metal forming process under coupled effects with multi-factors, such as geometry sizes of rolls and ring blank, material, forming process parameters and friction, etc. Amon...Cold ring rolling is an advanced but complex metal forming process under coupled effects with multi-factors, such as geometry sizes of rolls and ring blank, material, forming process parameters and friction, etc. Among these factors, friction between rolls and ring blank plays an important role in keeping the stable forming of cold ring rolling. An analytical method was firstly presented for proximately determining the critical friction coefficient of stable forming and then a method was proposed to determine the critical friction coefficient by combining analytical method with numerical simulation. And the influence of friction coefficient on the quality of end-plane and side spread of ring,rolling force, rolling moment and metal flow characteristic in the cold ring rolling process have been explored using the three dimensional （3D） numerical simulation based on the elastic-plastic dynamic finite element method （FEM） under the ABAQUS software environment, and the results show that increasing the friction on the contact surfaces between rolls and ring blank is useful not only for improving the stability of cold ring rolling but also for improving the geometry and dimension precision of deformed ring.展开更多
The effect of magnetic field on the tribological process of sleeve-ring pair lubricated by WRL lubricants was investigated by means of a NG-x wear tester and a PS5013 video microscope. The friction coefficient(f) and ...The effect of magnetic field on the tribological process of sleeve-ring pair lubricated by WRL lubricants was investigated by means of a NG-x wear tester and a PS5013 video microscope. The friction coefficient(f) and the wear weight(W) in lubricating test with WRL lubricant were decreased with the increase in the magnetic field vertical to the rubbing surface, and an almost zero wear lubricating situation was gained in a magnetic field of 1000A/m. The captured wear micro particles on the rubbing surface were observed in the testing process, and the theoretical analysis of magnetic effects was completed. It is indicated that the magnetic field has not only a capturing action of wear micro particles on the worn surface, but also a inducing polarization of magnetic anisotropy of lubricant molecular. The actions promote the absorption of WRL lubricant into the wear surface as well as wear micro-particles, so that a good tribological effect is obtained when both magnetic field and WRL present.展开更多
Based on analysis of flow field of the rotary seal using sealing ring, mechanical models under the condition of full film friction and mixed film friction were established respectively. The influence of friction state...Based on analysis of flow field of the rotary seal using sealing ring, mechanical models under the condition of full film friction and mixed film friction were established respectively. The influence of friction state of the sealing ring on seal performance was also discussed. The relation between force characteristic and structural parameters of the sealing ring was analyzed. Analytical results indicate that friction state mainly depends on structural parameters of the sealing ring. The expression of calculating friction torque under the condition of mixed film friction was deduced. Experiment verification had been done. Experimental results agree with the deducing theoretical conclusions on the whole. It lays the foundation for design of new type of sealing ring used in composite transmission.展开更多
In this study a neural network approach is proposed to realize an automatic numerical prediction of the interfacial friction factor and the flow stress of materials. Decrease in the inner diameter and reduction in the...In this study a neural network approach is proposed to realize an automatic numerical prediction of the interfacial friction factor and the flow stress of materials. Decrease in the inner diameter and reduction in the height of the ring are taken as input展开更多
文摘Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission.Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period.Therefore,it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine.Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine.The frictional forces,wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester.The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin.Several coatings on the ring specimen were used,such as DLC,TiN,Cr-ceramic and TiAlN,in order to improve the tribological characteristics of the ring.The coefficients of friction were monitored during the tests,and the wear volumes of the piston ring surfaces with various coatings were compared.Test results show that the DLC coating exhibits better tribological properties than the other coatings.The graphite structure of this coating is responsible for the low friction and wear of the DLC film.The TiN and DLC coatings show better scuffing resistance than the other coatings.The TiN and Cr-ceramic coated rings show good wear resistance and high friction.
基金The authors thank the National Natural Science Foundation of China for Key Program of China(No．50335060)the National Science Found of China for Distinguished Young Scholars(No．50225518)for the support on this research．
文摘Cold ring rolling is an advanced but complex metal forming process under coupled effects with multi-factors, such as geometry sizes of rolls and ring blank, material, forming process parameters and friction, etc. Among these factors, friction between rolls and ring blank plays an important role in keeping the stable forming of cold ring rolling. An analytical method was firstly presented for proximately determining the critical friction coefficient of stable forming and then a method was proposed to determine the critical friction coefficient by combining analytical method with numerical simulation. And the influence of friction coefficient on the quality of end-plane and side spread of ring,rolling force, rolling moment and metal flow characteristic in the cold ring rolling process have been explored using the three dimensional （3D） numerical simulation based on the elastic-plastic dynamic finite element method （FEM） under the ABAQUS software environment, and the results show that increasing the friction on the contact surfaces between rolls and ring blank is useful not only for improving the stability of cold ring rolling but also for improving the geometry and dimension precision of deformed ring.
文摘The effect of magnetic field on the tribological process of sleeve-ring pair lubricated by WRL lubricants was investigated by means of a NG-x wear tester and a PS5013 video microscope. The friction coefficient(f) and the wear weight(W) in lubricating test with WRL lubricant were decreased with the increase in the magnetic field vertical to the rubbing surface, and an almost zero wear lubricating situation was gained in a magnetic field of 1000A/m. The captured wear micro particles on the rubbing surface were observed in the testing process, and the theoretical analysis of magnetic effects was completed. It is indicated that the magnetic field has not only a capturing action of wear micro particles on the worn surface, but also a inducing polarization of magnetic anisotropy of lubricant molecular. The actions promote the absorption of WRL lubricant into the wear surface as well as wear micro-particles, so that a good tribological effect is obtained when both magnetic field and WRL present.
基金Sponsored by the Ministerial Level Foundation (404020806)
文摘Based on analysis of flow field of the rotary seal using sealing ring, mechanical models under the condition of full film friction and mixed film friction were established respectively. The influence of friction state of the sealing ring on seal performance was also discussed. The relation between force characteristic and structural parameters of the sealing ring was analyzed. Analytical results indicate that friction state mainly depends on structural parameters of the sealing ring. The expression of calculating friction torque under the condition of mixed film friction was deduced. Experiment verification had been done. Experimental results agree with the deducing theoretical conclusions on the whole. It lays the foundation for design of new type of sealing ring used in composite transmission.
文摘In this study a neural network approach is proposed to realize an automatic numerical prediction of the interfacial friction factor and the flow stress of materials. Decrease in the inner diameter and reduction in the height of the ring are taken as input
