In order to confirm the early failure cause of a four-row cylindrical roller bearing at the backup roll position of a six-high cold sheet mill, its lubrication behavior under harsh operating conditions is investigated...In order to confirm the early failure cause of a four-row cylindrical roller bearing at the backup roll position of a six-high cold sheet mill, its lubrication behavior under harsh operating conditions is investigated. Through establishing and solving the Elastohydrodynamic Lubrication (EHL) model of the roller-inner raceway contact region, the minimum oil film thickness and the real lubrication performance are achieved. The results show the bearing failures come from the poor oil film thickness in the case of high temperature and low rotational speed, which leads to contact wear. So various approaches to improve bearing life via improving lubrication are compared. It has been proved decreasing surface roughness of both contact bodies is an effective way.展开更多
The effects of oil film on the rolled surface, including surface roughness and topography, were investigated during cold rolling of aluminum strips. Various mineral oils with viscosities from 0.10 to 1.6 Pa.s were use...The effects of oil film on the rolled surface, including surface roughness and topography, were investigated during cold rolling of aluminum strips. Various mineral oils with viscosities from 0.10 to 1.6 Pa.s were used to obtain different oil film thicknesses. Results from experiment and calculation show that the thicker oil film protects the initial roughening surface so that it leads to an increase in roughness of the rolled surface, in particular when the surface roughness has the character of direction. The rolled surface roughness was determined by 2, which is the ratio of oil film thickness to the combined surface roughness. When 2 〉 3, the rolled surface roughness increases rapidly with the increase in oil viscosity, whereas the surface roughening has already occurred when 2 〈 3, but the increase of the rolled surface roughness with increasing viscosity is not distinct.展开更多
The cooling and lubrication process is one of the key processes in cold rolling,as it not only determines surface quality and strip shape,but also reduces the rolling power consumption and extends the life of the roll...The cooling and lubrication process is one of the key processes in cold rolling,as it not only determines surface quality and strip shape,but also reduces the rolling power consumption and extends the life of the roll even during high-speed operation.In this study,an innovative method combining emulsion lubrication and neat oil lubrication was used to solve some problems associated with individual passes.Laboratory tests on stainless steel strips showed that this new lubrication method could improve the surface quality of the strip,control the rolling friction in the deformation zone,and has the potential of making lubrication systems simpler and easier to operate,all while reducing the negative environmental impact from emulsion processing.展开更多
The 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole(T561), benzotriazole(BTA), 1-N, N-bis(2-ethylhexyl) aminomethyl-4-methyl-1h-benzotriazole(IRGAMET39) and 1-[N, N-bis(2-ethylhexyl) aminomethyl] methyl benzotriazole(TTLX)...The 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole(T561), benzotriazole(BTA), 1-N, N-bis(2-ethylhexyl) aminomethyl-4-methyl-1h-benzotriazole(IRGAMET39) and 1-[N, N-bis(2-ethylhexyl) aminomethyl] methyl benzotriazole(TTLX) have been evaluated as corrosion inhibitors used in rolling oil for cold rolling of copper foil. The MRS-10A four-ball friction and wear tests have been carried out to compare their tribological properties, and the lubricating performance of rolling oils has been studied through rolling experiments. The oil sample containing IRGAMET 39 has the same PB value as that one containing T561, with the coefficient of friction increased by 35.6% and wear scar diameter decreased by 4%. The minimum rolling gauge has been studied after rolling lubrication, but the results show that inhibitors have no effect on it. Scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS) analyses have indicated that the inhibitor is adsorbed on the copper surface to prevent copper from being corroded easily. In addition, the LEXT OLS4000 laser confocal microscopy has been used to observe the foil surface which shows that the streaks of foil surface are clear, the scratches are shallow and the surface failure is improved effectively.展开更多
Various kinds of base oils were applied to cold rolling aluminum strips on a test mill for evaluationof the influences of these base oils,aromatics contents and viscosity of base oils on their lubricating performances...Various kinds of base oils were applied to cold rolling aluminum strips on a test mill for evaluationof the influences of these base oils,aromatics contents and viscosity of base oils on their lubricating performances and surface reflectivity of rolled strips at annealing. Results showed that low friction coefficient androlling force were obtained by using the normal paraffins,whereas their contaminations on the annealed stripsurface were the same as those of other saturated hydrocarbons. Aromatics in base oil affected the stir face reflectivity of annealed strips, but the decrease of aromatics in base oil was ineffective to improve rolled stripssurface quality when it is less than 1 %. Base oil viscosity has the great influences on the lubricating performances and surface reflectivity of annealed strips just in this condition.展开更多
Appropriate base oils and homologous additives such as extreme pressure and anti-wear agents,oiliness agents and antioxidants were selected,and experiments testing the compatibility performance between additive,base o...Appropriate base oils and homologous additives such as extreme pressure and anti-wear agents,oiliness agents and antioxidants were selected,and experiments testing the compatibility performance between additive,base oil and other components were carried out to develop the SK and SD series of rolling oils for cold rolling of stainless steel.The developed oils were used in the stainless steel cold rolling lubrication experiments,and were successfully applied in the actual cold rolling operation of stainless steel.Compared with a foreign product,the tribological properties,the thermal oxidation stability,and the rolling lubrication performance of the developed stainless steel cold rolling oils were studied.Test results showed that the tribological properties of the thereby developed rolling oils and the reference one were almost at the same level,and to some extent the performance of rolling was even better than the foreign product,at the same time the stainless steel sheet could retain its well annealed performance.Meanwhile,within a certain range,the lubrication of the rolling oil became better as its viscosity increased at the same level of saponification value,which could provide a lower friction coefficient,so that a higher maximum reduction ratio of the rolled piece through a constant roll gap and a minimum thickness could be secured.Also,similar phenomena appeared as the saponification value increased at a same viscosity level of the rolling oils.展开更多
The theory of failure of rolling contact bearings is based on fluctuating high level loading and material fatigue. This theory is unimodal, considering only the solid components of the bearing, and ignoring the liquid...The theory of failure of rolling contact bearings is based on fluctuating high level loading and material fatigue. This theory is unimodal, considering only the solid components of the bearing, and ignoring the liquid phase, which is the lubricant. Bearing life is rather dispersed, reaching a ratio of 20 between the extreme values. Since this theory was established, several exceptional phenomena were detected that could not be explained by it, such as: 1) Pitting damage beyond the contact path;2) Detrimental effect of a minute quantity of water in the lubricant on bearing life. 25 ppm of water in the lubricant brought about shorter bearing life by over than 30%. The bimodal failure theory considers both solid and liquid bearing components. The damaging process of the lubricant evolves from its cavitation. During this process vapor filled cavities are formed in low pressure zones. When these cavities reach high pressure zones they implode exothermally. These implosions cause local high pressure pulses reaching 30,000 at accompanied by a temperature rise of about 2000 degrees K [<a href="#ref1">1</a>]. This paper includes cavitation erosion test results on stainless steel samples by vibratory and water tunnel test rigs. Various methods of lubricant dehydration are presented and evaluated. The main conclusion from this analysis is the use of water-free lubricants, for long life of RC bearings and more uniform service life thereof.展开更多
An analytical model for metal rolling in the mixed lubrication regime was developed based on Wilson and Chang’s asperity flattening model and Von Mises homogenous deformation model. A more rigorous average Reynolds e...An analytical model for metal rolling in the mixed lubrication regime was developed based on Wilson and Chang’s asperity flattening model and Von Mises homogenous deformation model. A more rigorous average Reynolds equation was used to calculate the hydrodynamic pressure. The variations of the yield stress with strain were considered in the model. An efficient iteration procedure was developed to solve the contact area, film thickness and hydrodynamic pressure. The model is more practical with fewer assumption and converges quickly. It is applicable to a wider range of rolling regimes. The calculation results using the model agree well with the literature as well as with measured data from a rolling mill.展开更多
<span><span><span style="font-family:Verdana;">The prevailing cumulative failure curves of Rolling Contact Bearings (RCB) have two main drawbacks: they begin at the origin and have a large ...<span><span><span style="font-family:Verdana;">The prevailing cumulative failure curves of Rolling Contact Bearings (RCB) have two main drawbacks: they begin at the origin and have a large dispersion. The purpose of this study is to develop an ideal failure curve and overcome the present drawbacks. The ideal failure curve of RC bearings is obtained by applying a water-free lubricant to the tested bearings. This eliminates the cavitation erosion from the Bimodal failure mechanism and the synergistic effect with the mechanical failure mode</span><span style="font-family:Verdana;">.</span></span></span><span><span><span> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">This</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> new concept considers the fatigue process involved in the failure mechanism and suggests decreasing the dispersion of bearing life.</span></span></span>展开更多
Lubrication in cold rolling process is used not only to control friction,but also to control surface quality and thermal chamber.Successful cold rolling of strip at high speeds requires an optimum presence of lubrican...Lubrication in cold rolling process is used not only to control friction,but also to control surface quality and thermal chamber.Successful cold rolling of strip at high speeds requires an optimum presence of lubricant film thickness at the contact.In order to have a better control on rolling process the awareness for the prediction and maintenance of desired minimum film thickness.On the basis of learning and summarizing the theories early founded by experts around the world,this paper constructed the mixed lubrication model. This paper investigated the lubrication state variation caused by oil and rolling condition differences by cold rolling experiments.The experiments indicated that oil has a big influence to rolling process,and rolling speed directly influence the lubrication state.展开更多
The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unste...The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unsteady inlet film thickness lack unsteady disturbance factors and do not take surface topography into consideration. In this paper, based on the hydrodynamic analysis of inlet zone an unsteady rolling film model which concerns the direction of surface topography is built up. Considering the small fluctuation of inlet angle, absolute reduction, reduction ratio, inlet strip thickness and roll radius as the input variables and the fluctuation of inlet film thickness as the output variable, the non-linear relationship between the input and output is discussed. The discussion results show that there is 180° phase difference between the inlet film thickness and the input variables, such as the fluctuant absolute reduction, the fluctuant reduction ratio and non-uniform inlet strip thickness, but there is no phase difference between unsteady roll radius and the output. The inlet angle, the steady roll radius and the direction of surface topography have significant influence on the fluctuant amplitude of unsteady inlet film thickness. This study proposes an analysis method for unsteady inlet film thickness which takes surface topography and new disturbance factors into consideration.展开更多
Bearings are key components in rotating machinery,which is widely used in many fields,such as CNC machines,wind turbines and induction machines.The increasingly harsh operation environment can lead to wear and tear on...Bearings are key components in rotating machinery,which is widely used in many fields,such as CNC machines,wind turbines and induction machines.The increasingly harsh operation environment can lead to wear and tear on raceways and reduce the precision and reliability of bearing or even machinery.Lubrication could relieve the wear to some degree,which is benefit to prolong the bearing’s life.Thus,investigation on the vibration responses under the influence of oil film is of great significance.However,for mechanism analysis,how to include the oil film into the bearing dynamic model affects the result and efficiency of solution.To address this problem,this study proposed a fast algorithm through load distribution and interpolation when calculating oil film stiffness and thickness during the solution of bearing vibration model.Analysis of oil film on vibration is carried out and a bearing test rig is designed to verify the proposed model.Numerical simulation result shows that rotational speed and load have vital effect on oil film and vibration.The experimental result is consistent with the simulation,which shows that the proposed model has a better performance on modeling bearing vibration and the method of considering oil film is reasonable.展开更多
Sliding and spinning behaviors significantly affect the performance of rolling bearings,especially for dry-lubricated bearings,micro and macro sliding may lead to increased wear of the solid lubricating film.A unified...Sliding and spinning behaviors significantly affect the performance of rolling bearings,especially for dry-lubricated bearings,micro and macro sliding may lead to increased wear of the solid lubricating film.A unified rolling contact tribology analytical model is proposed for dry-lubricated angular contact ball bearings(ACBBs)considering the extreme conditions including high combined loads and rolling contact effects.A comprehensive solution framework is proposed to ensure the robustness of the model under different loading conditions.Equilibrium equations are solved to study the effects of friction coefficients,rotating speeds,and combined loads on the skidding and spinning characteristics of the ACBB.The results show that the rolling contact effects and combined loads significantly affect the skidding and spinning performance of the ACBB.Further analysis reveals that the skidding mechanism is related to the interaction between ball kinematical motion and traction forces.The developed analytical model is proved to more accurately predict the bearing kinematical and tribological behavior as it discards the raceway control hypothesis and considers the macro/micro-slipping,creepage,and self-spinning motions of the ball,which is validated using both the existing pure axial loading dry-lubricated ACBB model and the classical Jones–Harris model.The study would provide some guidance for the structure and lubrication design of dry-lubricated ACBBs.展开更多
基金This paper is supported by National Natural Science Fundation of China under Grant No.50405030.
文摘In order to confirm the early failure cause of a four-row cylindrical roller bearing at the backup roll position of a six-high cold sheet mill, its lubrication behavior under harsh operating conditions is investigated. Through establishing and solving the Elastohydrodynamic Lubrication (EHL) model of the roller-inner raceway contact region, the minimum oil film thickness and the real lubrication performance are achieved. The results show the bearing failures come from the poor oil film thickness in the case of high temperature and low rotational speed, which leads to contact wear. So various approaches to improve bearing life via improving lubrication are compared. It has been proved decreasing surface roughness of both contact bodies is an effective way.
文摘The effects of oil film on the rolled surface, including surface roughness and topography, were investigated during cold rolling of aluminum strips. Various mineral oils with viscosities from 0.10 to 1.6 Pa.s were used to obtain different oil film thicknesses. Results from experiment and calculation show that the thicker oil film protects the initial roughening surface so that it leads to an increase in roughness of the rolled surface, in particular when the surface roughness has the character of direction. The rolled surface roughness was determined by 2, which is the ratio of oil film thickness to the combined surface roughness. When 2 〉 3, the rolled surface roughness increases rapidly with the increase in oil viscosity, whereas the surface roughening has already occurred when 2 〈 3, but the increase of the rolled surface roughness with increasing viscosity is not distinct.
文摘The cooling and lubrication process is one of the key processes in cold rolling,as it not only determines surface quality and strip shape,but also reduces the rolling power consumption and extends the life of the roll even during high-speed operation.In this study,an innovative method combining emulsion lubrication and neat oil lubrication was used to solve some problems associated with individual passes.Laboratory tests on stainless steel strips showed that this new lubrication method could improve the surface quality of the strip,control the rolling friction in the deformation zone,and has the potential of making lubrication systems simpler and easier to operate,all while reducing the negative environmental impact from emulsion processing.
基金financially supported by the National Natural Science Foundation of China (No.51274037)the Key Science and Technology Project of China (No.2011BAE23B00)the Cooperation Program between USTB and SINOPEC (No.112116)
文摘The 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole(T561), benzotriazole(BTA), 1-N, N-bis(2-ethylhexyl) aminomethyl-4-methyl-1h-benzotriazole(IRGAMET39) and 1-[N, N-bis(2-ethylhexyl) aminomethyl] methyl benzotriazole(TTLX) have been evaluated as corrosion inhibitors used in rolling oil for cold rolling of copper foil. The MRS-10A four-ball friction and wear tests have been carried out to compare their tribological properties, and the lubricating performance of rolling oils has been studied through rolling experiments. The oil sample containing IRGAMET 39 has the same PB value as that one containing T561, with the coefficient of friction increased by 35.6% and wear scar diameter decreased by 4%. The minimum rolling gauge has been studied after rolling lubrication, but the results show that inhibitors have no effect on it. Scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS) analyses have indicated that the inhibitor is adsorbed on the copper surface to prevent copper from being corroded easily. In addition, the LEXT OLS4000 laser confocal microscopy has been used to observe the foil surface which shows that the streaks of foil surface are clear, the scratches are shallow and the surface failure is improved effectively.
文摘Various kinds of base oils were applied to cold rolling aluminum strips on a test mill for evaluationof the influences of these base oils,aromatics contents and viscosity of base oils on their lubricating performances and surface reflectivity of rolled strips at annealing. Results showed that low friction coefficient androlling force were obtained by using the normal paraffins,whereas their contaminations on the annealed stripsurface were the same as those of other saturated hydrocarbons. Aromatics in base oil affected the stir face reflectivity of annealed strips, but the decrease of aromatics in base oil was ineffective to improve rolled stripssurface quality when it is less than 1 %. Base oil viscosity has the great influences on the lubricating performances and surface reflectivity of annealed strips just in this condition.
文摘Appropriate base oils and homologous additives such as extreme pressure and anti-wear agents,oiliness agents and antioxidants were selected,and experiments testing the compatibility performance between additive,base oil and other components were carried out to develop the SK and SD series of rolling oils for cold rolling of stainless steel.The developed oils were used in the stainless steel cold rolling lubrication experiments,and were successfully applied in the actual cold rolling operation of stainless steel.Compared with a foreign product,the tribological properties,the thermal oxidation stability,and the rolling lubrication performance of the developed stainless steel cold rolling oils were studied.Test results showed that the tribological properties of the thereby developed rolling oils and the reference one were almost at the same level,and to some extent the performance of rolling was even better than the foreign product,at the same time the stainless steel sheet could retain its well annealed performance.Meanwhile,within a certain range,the lubrication of the rolling oil became better as its viscosity increased at the same level of saponification value,which could provide a lower friction coefficient,so that a higher maximum reduction ratio of the rolled piece through a constant roll gap and a minimum thickness could be secured.Also,similar phenomena appeared as the saponification value increased at a same viscosity level of the rolling oils.
文摘The theory of failure of rolling contact bearings is based on fluctuating high level loading and material fatigue. This theory is unimodal, considering only the solid components of the bearing, and ignoring the liquid phase, which is the lubricant. Bearing life is rather dispersed, reaching a ratio of 20 between the extreme values. Since this theory was established, several exceptional phenomena were detected that could not be explained by it, such as: 1) Pitting damage beyond the contact path;2) Detrimental effect of a minute quantity of water in the lubricant on bearing life. 25 ppm of water in the lubricant brought about shorter bearing life by over than 30%. The bimodal failure theory considers both solid and liquid bearing components. The damaging process of the lubricant evolves from its cavitation. During this process vapor filled cavities are formed in low pressure zones. When these cavities reach high pressure zones they implode exothermally. These implosions cause local high pressure pulses reaching 30,000 at accompanied by a temperature rise of about 2000 degrees K [<a href="#ref1">1</a>]. This paper includes cavitation erosion test results on stainless steel samples by vibratory and water tunnel test rigs. Various methods of lubricant dehydration are presented and evaluated. The main conclusion from this analysis is the use of water-free lubricants, for long life of RC bearings and more uniform service life thereof.
文摘An analytical model for metal rolling in the mixed lubrication regime was developed based on Wilson and Chang’s asperity flattening model and Von Mises homogenous deformation model. A more rigorous average Reynolds equation was used to calculate the hydrodynamic pressure. The variations of the yield stress with strain were considered in the model. An efficient iteration procedure was developed to solve the contact area, film thickness and hydrodynamic pressure. The model is more practical with fewer assumption and converges quickly. It is applicable to a wider range of rolling regimes. The calculation results using the model agree well with the literature as well as with measured data from a rolling mill.
文摘<span><span><span style="font-family:Verdana;">The prevailing cumulative failure curves of Rolling Contact Bearings (RCB) have two main drawbacks: they begin at the origin and have a large dispersion. The purpose of this study is to develop an ideal failure curve and overcome the present drawbacks. The ideal failure curve of RC bearings is obtained by applying a water-free lubricant to the tested bearings. This eliminates the cavitation erosion from the Bimodal failure mechanism and the synergistic effect with the mechanical failure mode</span><span style="font-family:Verdana;">.</span></span></span><span><span><span> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">This</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> new concept considers the fatigue process involved in the failure mechanism and suggests decreasing the dispersion of bearing life.</span></span></span>
文摘Lubrication in cold rolling process is used not only to control friction,but also to control surface quality and thermal chamber.Successful cold rolling of strip at high speeds requires an optimum presence of lubricant film thickness at the contact.In order to have a better control on rolling process the awareness for the prediction and maintenance of desired minimum film thickness.On the basis of learning and summarizing the theories early founded by experts around the world,this paper constructed the mixed lubrication model. This paper investigated the lubrication state variation caused by oil and rolling condition differences by cold rolling experiments.The experiments indicated that oil has a big influence to rolling process,and rolling speed directly influence the lubrication state.
基金Supported by National Natural Science Foundation of China(Grant No.51175035)PhD Program Foundation of Ministry of Education of China(Grant No.20100006110024)Beijing Higher Education Young Elite Teacher Project of China(Grant No.YETP0367)
文摘The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unsteady inlet film thickness lack unsteady disturbance factors and do not take surface topography into consideration. In this paper, based on the hydrodynamic analysis of inlet zone an unsteady rolling film model which concerns the direction of surface topography is built up. Considering the small fluctuation of inlet angle, absolute reduction, reduction ratio, inlet strip thickness and roll radius as the input variables and the fluctuation of inlet film thickness as the output variable, the non-linear relationship between the input and output is discussed. The discussion results show that there is 180° phase difference between the inlet film thickness and the input variables, such as the fluctuant absolute reduction, the fluctuant reduction ratio and non-uniform inlet strip thickness, but there is no phase difference between unsteady roll radius and the output. The inlet angle, the steady roll radius and the direction of surface topography have significant influence on the fluctuant amplitude of unsteady inlet film thickness. This study proposes an analysis method for unsteady inlet film thickness which takes surface topography and new disturbance factors into consideration.
基金supported by Key Program of National Natural Science Foundation of China (52035002)National Natural Science Foundation of China (51805353).
文摘Bearings are key components in rotating machinery,which is widely used in many fields,such as CNC machines,wind turbines and induction machines.The increasingly harsh operation environment can lead to wear and tear on raceways and reduce the precision and reliability of bearing or even machinery.Lubrication could relieve the wear to some degree,which is benefit to prolong the bearing’s life.Thus,investigation on the vibration responses under the influence of oil film is of great significance.However,for mechanism analysis,how to include the oil film into the bearing dynamic model affects the result and efficiency of solution.To address this problem,this study proposed a fast algorithm through load distribution and interpolation when calculating oil film stiffness and thickness during the solution of bearing vibration model.Analysis of oil film on vibration is carried out and a bearing test rig is designed to verify the proposed model.Numerical simulation result shows that rotational speed and load have vital effect on oil film and vibration.The experimental result is consistent with the simulation,which shows that the proposed model has a better performance on modeling bearing vibration and the method of considering oil film is reasonable.
基金This work was funded by the National Natural Science Foundation of China(Nos.52175119 and 61633001).The authors are also grateful for the support of Xi’an Aerospace Propulsion Institution(China Aerospace Science and Technology Corporation).
文摘Sliding and spinning behaviors significantly affect the performance of rolling bearings,especially for dry-lubricated bearings,micro and macro sliding may lead to increased wear of the solid lubricating film.A unified rolling contact tribology analytical model is proposed for dry-lubricated angular contact ball bearings(ACBBs)considering the extreme conditions including high combined loads and rolling contact effects.A comprehensive solution framework is proposed to ensure the robustness of the model under different loading conditions.Equilibrium equations are solved to study the effects of friction coefficients,rotating speeds,and combined loads on the skidding and spinning characteristics of the ACBB.The results show that the rolling contact effects and combined loads significantly affect the skidding and spinning performance of the ACBB.Further analysis reveals that the skidding mechanism is related to the interaction between ball kinematical motion and traction forces.The developed analytical model is proved to more accurately predict the bearing kinematical and tribological behavior as it discards the raceway control hypothesis and considers the macro/micro-slipping,creepage,and self-spinning motions of the ball,which is validated using both the existing pure axial loading dry-lubricated ACBB model and the classical Jones–Harris model.The study would provide some guidance for the structure and lubrication design of dry-lubricated ACBBs.