Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function ...Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function of the longitudinal section of the beaver tooth rake face is extracted,and its variable curvature characteristics are analyzed.Based on this,a turning tool with variable curvature directrix configuration rake face is designed.The cutting force experiment and machining surface quality analysis experiment were carried out with the designed tool and the linear directrix configuration rake face tool respectively.The measured data of the variable curvature directrix configuration rake face tool is better than the linear directrix configuration rake face tool and its drag reduction performance of the tool is verified by experiments.Through the analysis of the working rake angle and shear angle of the tool with variable curvature directrix configuration rake face,the relationship between the parameters of the variable curvature directrix function and the working rake angle,and shear angle has been obtained.By the method of finite element simulation analysis,the stress field in the cutting zone of two different configuration tools has been analyzed.It has been found that the tool with variable curvature directrix rake face has a‘bending moment'effect on the tool-chip interface due to its curved surface configuration,and a‘prying'effect at the tool tip.These two effects promote the separation of chips from the workpiece and make the cutting process more forcesaving.The research of this paper will have reference significance for the design and application of the curved surface configuration rake face tool.展开更多
Large torque can be output by the single gimbal control momentum gyroscope (SGCMG) based on the principle of the gyroscopic precession. However, the singularity is a major obstacle to successfully implement the task o...Large torque can be output by the single gimbal control momentum gyroscope (SGCMG) based on the principle of the gyroscopic precession. However, the singularity is a major obstacle to successfully implement the task of the attitude control. The singularity can be avoided by the additional variable flywheel speed of variable speed control moment gyroscopes (VSCMG). Unfortunately, some kind of singularity cannot be effectively avoided. Consequently, the output toque can be only supported by the reaction torque of the flywheel when the singularity is encountered, and the consume power that is determined by the flywheel speed and reaction torque can be greatly increased when the flywheel spin rate over one thousand revolutions per minute. In this paper, the pyramid configuration with variable skew angle of the VSCMG is considered. A new steering law for the VSCMG with variable skew angle is proposed. The singularity that cannot be avoided by the varying flywheel speed can be effectively avoided with assisting of varying the skew angle. Consequently, the requirement of flywheel torque can be reduced. At last, the optimizing VSCMG with variable skew angle can be cast as a multi-objective function with multi-constraints. The particle swarm optimization method is used to solve the optimizing problem. In summary, the VSCMG with variable skew angle can be redesigned with considering of the singularity avoidance and minimizing system power.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51975003)。
文摘Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function of the longitudinal section of the beaver tooth rake face is extracted,and its variable curvature characteristics are analyzed.Based on this,a turning tool with variable curvature directrix configuration rake face is designed.The cutting force experiment and machining surface quality analysis experiment were carried out with the designed tool and the linear directrix configuration rake face tool respectively.The measured data of the variable curvature directrix configuration rake face tool is better than the linear directrix configuration rake face tool and its drag reduction performance of the tool is verified by experiments.Through the analysis of the working rake angle and shear angle of the tool with variable curvature directrix configuration rake face,the relationship between the parameters of the variable curvature directrix function and the working rake angle,and shear angle has been obtained.By the method of finite element simulation analysis,the stress field in the cutting zone of two different configuration tools has been analyzed.It has been found that the tool with variable curvature directrix rake face has a‘bending moment'effect on the tool-chip interface due to its curved surface configuration,and a‘prying'effect at the tool tip.These two effects promote the separation of chips from the workpiece and make the cutting process more forcesaving.The research of this paper will have reference significance for the design and application of the curved surface configuration rake face tool.
文摘Large torque can be output by the single gimbal control momentum gyroscope (SGCMG) based on the principle of the gyroscopic precession. However, the singularity is a major obstacle to successfully implement the task of the attitude control. The singularity can be avoided by the additional variable flywheel speed of variable speed control moment gyroscopes (VSCMG). Unfortunately, some kind of singularity cannot be effectively avoided. Consequently, the output toque can be only supported by the reaction torque of the flywheel when the singularity is encountered, and the consume power that is determined by the flywheel speed and reaction torque can be greatly increased when the flywheel spin rate over one thousand revolutions per minute. In this paper, the pyramid configuration with variable skew angle of the VSCMG is considered. A new steering law for the VSCMG with variable skew angle is proposed. The singularity that cannot be avoided by the varying flywheel speed can be effectively avoided with assisting of varying the skew angle. Consequently, the requirement of flywheel torque can be reduced. At last, the optimizing VSCMG with variable skew angle can be cast as a multi-objective function with multi-constraints. The particle swarm optimization method is used to solve the optimizing problem. In summary, the VSCMG with variable skew angle can be redesigned with considering of the singularity avoidance and minimizing system power.
