Structure Improvement and Optimization of Gantry Milling System for Complex Boring and Milling Machining Center

To enhance the efficiency and machining precision of the TX1600G complex boring and milling machining center,a study was conducted on the structure of its gantry milling system.This study aimed to mitigate the influence of factors such as structural quality,natural frequency,and stiffness.The approach employed for this investigation involved mechanism topology optimization.To initiate this process,a finite element model of the gantry milling system structure was established.Subsequently,an objective function,comprising strain energy and modal eigenvalues,was synthesized.This objective function was optimized through multi-objective topology optimization,taking into account certain mass fraction constraints and considering various factors,including processing technology.The ultimate goal of this optimization was to create a gantry milling structure that exhibited high levels of dynamic and static stiffness,a superior natural frequency,and reduced mass.To validate the effectiveness of these topology optimization results,a comparison was made between the new and previous structures.The findings of this study serve as a valuable reference for optimizing the structure of other components within the machining center.

MAINTAINABLE MECHANISM OF MESO-β SCALE CONVECTIVE SYSTEM

By means of the Penn State-NCAR Mesoscale Model Version 5(MM5)with a horizontal resolution of 20 km.the maintainable mechanism of Meso-β scale Convective System(Mβ CS)has been investigated on the basis of simulation of the temporal and spatial thermodynamics structure of the MβCS which occurred in Wuhan and its surroundings on 21 July 1998.The occurrence of the significant warm-core in the center of the MβCS happened in Changjiang River Basin between the Mufu Mountain and the Dabie Mountain.To the southern side of the MβCS,there exist the southwest low-level jet(LLJ)and the vertical secondary circulation in the low and middle troposphere respectively.In respect to the northern of the MβCS,the northwest jet emerges in the upper troposphere,accompanied with cold and dry atmosphere downdrafts,resulting in another secondary circulation.The foregoing mentioned vertical wind shear provides a favorable dynamical environment for the intensification and maintenance of the MβCS.Equally important,the latent heat release associated with the MβCS produces the warm center in the middle troposphere and the pressure falls.The pressure drop then accelerates air parcels toward the low leading to strong convergence as well as the intensified convection,establishing a positive feedback between the convection and the latent heat release,which is the thermodynamic mechanism of the development and maintenance of the MβCS.