42CrMo steel has the characteristics of high strength,high wear resistance,high impact resistance,and fatigue resistance.Therefore,drilling 42CrMo steel has always been a challenging task.The indexable drill bit has t...42CrMo steel has the characteristics of high strength,high wear resistance,high impact resistance,and fatigue resistance.Therefore,drilling 42CrMo steel has always been a challenging task.The indexable drill bit has the advantages of high processing efficiency and low processing cost and has been widely used in the field of aerospace hole processing.To better understand the machining mechanism of the indexable drill bit,this paper uses the Coupled EulerianLagrangian method(CEL)to simulate the three-dimensional drilling model for the first time.The simulation results of the drilling force obtained by the CEL method and Lagrangian method are compared with the experimental results.It is verified that the CEL method is easy to converge and can avoid the problem of program interruption caused by mesh distortion,and the CEL simulation value is more consistent with the actual value.Secondly,the simulation results of cutting force and blade cutting edge node temperature under different process parameters are extracted.The variation of time domain cutting force,frequency domain cutting force and tool temperature with process parameters are obtained.This study provides a new method for the prediction of cutting performance and the optimization of process parameters of indexable drills.展开更多
The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions f...The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.展开更多
Currently,a non-geocentric geodetic coordinate system introduced in 1942(CS42),based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977,is used for geodetic works in the Republic of ...Currently,a non-geocentric geodetic coordinate system introduced in 1942(CS42),based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977,is used for geodetic works in the Republic of Uzbekistan.The development of the GNSS network proposes a task of transition to a new geocentric system based on the World Geodetic System 1984(WGS84)ellipsoid.Many software products adopt 3-or 7-parameter conversions,which can cause errors up to several meters and are not suitable for many applications.In this case,local transformations using a grid of differences between observation points with known coordinates in both datums would give the best accuracy.In this paper,we discuss various interpolation methods(Kriging,Minimum Curvature,Inverse Distance to a Power and Radial Basis Function)to solve the distortion modeling between CS42 and WGS84 systems for national datum improvement.The results show that the distortion models share a common tendency for all interpolation methods:the maximum horizontal displacements are concentrated along the West Tien Shan lineament,which is the boundary of the relief lowering.The discrepancies between the grid-based(calculated)and GPS-measured coordinates are evaluated.Statistical and spatial analysis has confirmed that for the co-ordinate transformation from CS42 to WGS84 and vice versa,grid-based transformation with Radial Basis Function interpolation has a high accuracy transformation.Analysis of the available data across the eastern part of the country shows that some positional distortions existed between the CS42 and WGS84 datums.For the best RBF method,the magnitude of these distortions is about 0.019-0.755 m with a standard deviation of 0.015 m.展开更多
基金supported by the Natural Science Foundation of Heilongjiang Province(No.TD2022E003)the National Natural Science Foundation of China(No.52175393)。
文摘42CrMo steel has the characteristics of high strength,high wear resistance,high impact resistance,and fatigue resistance.Therefore,drilling 42CrMo steel has always been a challenging task.The indexable drill bit has the advantages of high processing efficiency and low processing cost and has been widely used in the field of aerospace hole processing.To better understand the machining mechanism of the indexable drill bit,this paper uses the Coupled EulerianLagrangian method(CEL)to simulate the three-dimensional drilling model for the first time.The simulation results of the drilling force obtained by the CEL method and Lagrangian method are compared with the experimental results.It is verified that the CEL method is easy to converge and can avoid the problem of program interruption caused by mesh distortion,and the CEL simulation value is more consistent with the actual value.Secondly,the simulation results of cutting force and blade cutting edge node temperature under different process parameters are extracted.The variation of time domain cutting force,frequency domain cutting force and tool temperature with process parameters are obtained.This study provides a new method for the prediction of cutting performance and the optimization of process parameters of indexable drills.
文摘The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.
基金the scientific and applied project of the Astronomical Institute of Uzbekistan with the financial support of the Academy of Sciences of the Republic of Uzbekistan
文摘Currently,a non-geocentric geodetic coordinate system introduced in 1942(CS42),based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977,is used for geodetic works in the Republic of Uzbekistan.The development of the GNSS network proposes a task of transition to a new geocentric system based on the World Geodetic System 1984(WGS84)ellipsoid.Many software products adopt 3-or 7-parameter conversions,which can cause errors up to several meters and are not suitable for many applications.In this case,local transformations using a grid of differences between observation points with known coordinates in both datums would give the best accuracy.In this paper,we discuss various interpolation methods(Kriging,Minimum Curvature,Inverse Distance to a Power and Radial Basis Function)to solve the distortion modeling between CS42 and WGS84 systems for national datum improvement.The results show that the distortion models share a common tendency for all interpolation methods:the maximum horizontal displacements are concentrated along the West Tien Shan lineament,which is the boundary of the relief lowering.The discrepancies between the grid-based(calculated)and GPS-measured coordinates are evaluated.Statistical and spatial analysis has confirmed that for the co-ordinate transformation from CS42 to WGS84 and vice versa,grid-based transformation with Radial Basis Function interpolation has a high accuracy transformation.Analysis of the available data across the eastern part of the country shows that some positional distortions existed between the CS42 and WGS84 datums.For the best RBF method,the magnitude of these distortions is about 0.019-0.755 m with a standard deviation of 0.015 m.
