Research On The Mechanical Properties And Structure Optimization Of The 5-DOF-Hybrid Robot

In recent years,there is an increasing demand for exquisite carving,but the production process of carving is complex,traditional handmade and conventional machine tool processing are both not suitable for the surface processing and three-dimensional sculpture carving industry.Therefore,this paper proposes a hybrid robot composed of gantry and parallel work head as a new type of carving processing equipment.Based on the new type of the-5-DOF-hybrid robot as the research object,this paper carried on the thorough research on the mechanical properties and structure of the hybrid robot optimization problem.Based on the static analysis,the distribution regularity of stress,strain and displacement of the robot,are obtained,and the weak link of the organization is found;the inherent frequency of the robot is obtained by the modal analysis in order to avoid resonance;Finally,the optimization of the robot structure is researched.On the premise of guarantee the strength and stiffness,the quality is reduced,laying the foundation for subsequent robot design.The following several aspects has done:Firstly,this paper insights into the mechanical structure of the robot,does the stress analysis to the gantry and parallel work head and establishes the corresponding mechanical model.The mapping relationship between cutting force and driving force by the principle of the robot space coordinate transformation and static mechanics inverse equation.The distribution of driving force in the whole working space is obtained by the driving force simulation calculation,then biggest driving force of each pole and their position are fond.The frame of the gantry reaction and parallel work head of gantry of forces are solved by the theoretical mechanics equilibrium equation,and provide the basis for the subsequent strength and rigidity checking.Secondly,the robot statics characteristic is obtained by carrying out finite element static analysis on the robot using the finite element analysis software ANSYS Workbench.At first establishes a simplified model of the hybrid robot by3 d design software SolidWorks,then imports the simplified model to ANSYS Workbench software,and analysis the stress,strain and displacement distribution cloud.The maximum stress,strain and displacement and the corresponding position on the gantry and parallel work head can be fond,according to the results of the distribution of the cloud,and then the weak link of hybrid robot is fond.The strength,stiffness and stability of the robot can be checked next.Thirdly,with the modal analysis,whether hybrid robot produce resonance can be verified.The natural frequency and vibration mode of the hybrid robot when it works normally can be obtained by the modal analysis of finite element software modules.Comparing with the vibration frequency caused by servo motor and electric spindle,whether produce resonance can be verifide If there is a resonance produced,some measures should be taken to avoid the resonance.Finally,in order to reduce the weight of parallel work head and gantry,then reduce the big inertia force which will impact the machining accuracy,the structure optimization has been carried on to the hybrid robot.Using topology optimization method,and calculating in the topology optimization module of ANSYS Workbench software.On the premise of guarantee the strength and stiffness constant,in order to reduce weight as the goal,the loop optimization process repeatedly,at last a more reasonable structure appeared.Studies show that the mechanical model established in this paper and the statics characteristic analysis can better reflect the organization's actual situation.Hybrid robot under the effect of the biggest driving force can still meet the requirements of strength and stiffness.The second order natural frequency of the robot is closely to the external vibration,some measures should be taken to avoid the resonance.The weight of the hybrid robot has decreased by 20%to 40%by the structural optimization.