Design And Structure Optimization Of Precision Casting Shell Manipulator

In order to solve the problems of low efficiency of manual shell making,harsh working environment and high labour intensity of workers in the production process of precision casting,this paper proposes an automated shell making production line solution,which can realize the automatic process of wax mould shell making from dipping,sand spreading and drying.The research object is the shell-making robot,and the general assembly model of the shell-making robot is established according to the working requirements of the shell-making robot,and kinematic simulation analysis,static simulation analysis,modal analysis and lightweight design are carried out to improve the overall comprehensive performance of the robot.The main contents include:1.Development of a general layout for the design of a precision casting shell-making production line programme,complete with modelling and analysis of the working principle of the manipulator.In order to complete the automated transformation of shell making in the precision casting process,a shell making production line scheme was developed,which can realize the automation process of wax mould shell making from dipping,spreading sand,drying and other multiple repetitive movements.The three-dimensional modelling of the manipulator was completed according to the technical requirements of shell making.2.Kinematic and static analysis of the manipulator.The kinetic analysis of the manipulator was completed by using Adams software to build the virtual prototype model of the manipulator,and the results of the displacement,velocity and acceleration curves at the centre of mass were obtained by adding constraints,driving,setting the simulation time and the number of simulation steps,and the results of the simulation post-processing showed that the manipulator was relatively smooth in the process of movement,which verified the rationality and reliability of the manipulator movement.At the same time,the static analysis of the key structure of the manipulator was completed using Ansys Workbench,and the simulation results on deformation and stress were obtained after the solution.The results show that the stiffness and strength of the shell-making manipulator meet the requirements under the most dangerous working conditions,but there is redundancy in the material and there is room for necessary improvement,which provides a basis for the optimal design of the manipulator.3.Lightweight design of the manipulator.According to the results of the static analysis,the topology of the gripper jaws and robot arm is optimized to reduce the mass of the robot,save material and reduce cost.The topology optimisation of the manipulator jaws and arm is completed using the optimisation module in Ansys Workbench.From the topology cloud diagram in the optimisation results,reasonable locations for material removal can be obtained,furthermore the relationship between the input dimensional parameters and output variables is obtained using response surface analysis of the dimensions,and the optimal dimensional parameters are finally obtained.Without affecting the strength and stiffness of the manipulator structure,the remove part of the manipulator jaw and the manipulator arm are reasonably removed after topology optimisation,comparing the mass of the jaw and the manipulator arm before and after optimisation,the jaw is reduced by40% of the mass before optimisation and the manipulator arm is reduced by 0.7202 kg,completing the lightweight design of the manipulator and improving the dynamic characteristics of the manipulator during operation The light weight design of the robot has been completed,improving the dynamic characteristics of the robot during operation.4.Modal analysis of the key structure of the manipulator.Comparing the 1st to 6th order inherent frequencies and vibration patterns of the key structure of the manipulator before and after optimisation,it was found that the first order inherent frequency of the clamping jaws was increased by 95 Hz through optimisation,and the first order inherent frequency of the optimised manipulator arm was increased by 15 Hz,which was as high as possible above the excitation frequency,thus avoiding the occurrence of resonance and greatly improving the positioning accuracy and service life of the manipulator.