To better understand and know the roles of cooling/lubrication medium in the cutting process and expand their applicability,uncoated cemented carbide tools are used in high-speed turning Ti6Al4V.Dry,cold air,minimal q...To better understand and know the roles of cooling/lubrication medium in the cutting process and expand their applicability,uncoated cemented carbide tools are used in high-speed turning Ti6Al4V.Dry,cold air,minimal quantity lubrication（MQL）,cryogenic MQL,and ionized air as the cooling/lubrication conditions are studied.Experimental results show that at speed 120 m/min turning Ti6Al4V,the cutting force under ionized air is smallest under all lubricant conditions,and tool life is best,next is cryogenic MQL.MQL and cold air almost have the same effect,a little better than dry.Meanwhile the smallest surface roughness is also obtained under ionized air condition.Flank wear and crater wear are the dominant failure modes when high-speed turning Ti6Al4V by SEM analysis.Finally the conclusion is drawn that ionized air and cryogenic MQL have better cooling/lubrication effects and can effectively improve the tool life.展开更多
The transmission efficiency, bulk temperature, integrate temperature, and scuffing load of test gears were investigated by a modified FZG rig. These values were measured in four different oil immersion depths with one...The transmission efficiency, bulk temperature, integrate temperature, and scuffing load of test gears were investigated by a modified FZG rig. These values were measured in four different oil immersion depths with one kind of potential oil that may be used to replace the current synthetic oil in order to find the reasonable lubricant quantity that meets not only the need of transmission performance but also the need of scuffing resistance for high-speed train gears. For the purpose of evaluating the efficiency of the test gears, there were two sensors added to measure the output torque of testing gears and the compensation torque of motor. The minimum lubrication film thickness at the pitch point was gained through an EHL model. The ratio of the film thickness A was used to identify the friction status when scuffing occurred at different oil levels. The results demonstrated that no matter what kind of the immersion depth was, the minimum film thickness on the pitch point was about 0.1 ~m and the ratio of film thickness was about 1.5 when scuffing occurred. According to the relationship of contact pressure and ratio of film thickness at the pitch point, it was found that the immersion depth of pinion should not be less than one module of the gear when the contact pressure of high-speed train gear at pitch point was about 580 MPa, which was the actual pressure at start-up stage.展开更多
基金Supported by the National Natural Science Foundation of China(50975141,51005118)~~
文摘To better understand and know the roles of cooling/lubrication medium in the cutting process and expand their applicability,uncoated cemented carbide tools are used in high-speed turning Ti6Al4V.Dry,cold air,minimal quantity lubrication（MQL）,cryogenic MQL,and ionized air as the cooling/lubrication conditions are studied.Experimental results show that at speed 120 m/min turning Ti6Al4V,the cutting force under ionized air is smallest under all lubricant conditions,and tool life is best,next is cryogenic MQL.MQL and cold air almost have the same effect,a little better than dry.Meanwhile the smallest surface roughness is also obtained under ionized air condition.Flank wear and crater wear are the dominant failure modes when high-speed turning Ti6Al4V by SEM analysis.Finally the conclusion is drawn that ionized air and cryogenic MQL have better cooling/lubrication effects and can effectively improve the tool life.
基金supported by the National Science and Technology Support Plan (Grant No. 2009BAG12A02-B02-102)
文摘The transmission efficiency, bulk temperature, integrate temperature, and scuffing load of test gears were investigated by a modified FZG rig. These values were measured in four different oil immersion depths with one kind of potential oil that may be used to replace the current synthetic oil in order to find the reasonable lubricant quantity that meets not only the need of transmission performance but also the need of scuffing resistance for high-speed train gears. For the purpose of evaluating the efficiency of the test gears, there were two sensors added to measure the output torque of testing gears and the compensation torque of motor. The minimum lubrication film thickness at the pitch point was gained through an EHL model. The ratio of the film thickness A was used to identify the friction status when scuffing occurred at different oil levels. The results demonstrated that no matter what kind of the immersion depth was, the minimum film thickness on the pitch point was about 0.1 ~m and the ratio of film thickness was about 1.5 when scuffing occurred. According to the relationship of contact pressure and ratio of film thickness at the pitch point, it was found that the immersion depth of pinion should not be less than one module of the gear when the contact pressure of high-speed train gear at pitch point was about 580 MPa, which was the actual pressure at start-up stage.
