| Wheel hubs are commonly used parts of automobiles.Forged wheels have a growing market demand due to their light weight and high strength.To improve the low production efficiency and poor safety of manual forging of wheel hub parts,it is of necessary significance to develop an automated production line for wheel hub forging.The key to improve the clamping stability and safety of hub forging robot is to break through the multi-degree of freedom and under-rank clamping of multi-type and multi-size hub forgings.Since the under-rank mechanism has the characteristics of simple control and strong adaptive stability,this thesis designs a wheel hub forging robot under-rank endpicker based on the under-rank principle,and the structure of the end pickup is analyzed,optimized and verified by experiments.Firstly,the structure design and kinematics analysis of the under-rank end picker of the hub forging robot were carried out.The whole structure scheme of the terminal is determined and the whole structure model is established according to the principle of under-rank.The kinematic model is established according to the motion principle of the endpicker.The validity of the motion of the under-rank enderpicker is preliminarily proved,and the theoretical basis for the motion simulation below is provided.Then,the static analysis and structural parameter optimization were carried out according to the under-rank endpicker model established.The contact force model of the end picker actuator was established based on the principle of virtual work in the adaptive clamping state;subsequently,the structural parameter optimization model was established with the requirement of the balance of the contact force,and a new adaptive small world algorithm(ASWA)and its optimization process were proposed;finally,the end picker was optimized based on the adaptive small world optimization algorithm,and the optimization results was compared with empirical method,Fmincon optimization function,genetic algorithm and basic small world algorithm.Numerical tests show that the optimization target value of the adaptive small-world algorithm in the article is the smallest,and it is reduced by 97.4%,62.9%,52.3%,and 42.2%.After showing the feasibility and superiority of ASWA in the optimization of under-rank endpicker,the structure optimization parameters of under-rank endpicker are obtained.Next,according to the high temperature environment where the wheel hub forging robot’s under-rank endpicker is located,the endpicker is thermodynamically analyzed and the thermal protection structure is optimized.Based on the finite element theory,the thermal load and static load of the under-rank endpicker are coupled.And the thermal stress distribution,stress and strain results of the key components of the end picker under the coupling force field were obtained.According to the thermal distribution nephogram,the thermal insulation optimization design and thermal structure coupling analysis of each finger joint of the end picker were carried out.The thermal insulation structure was analyzed according to the equivalent stress results of the thermal insulation structure Topology optimization of end picker.The numerical analysis shows that,compared with the structure before optimization,the temperature of the first,middle,and end knuckles of the heat insulation optimized rear end pickup at the reference node is reduced by 33.78%,50.42%,and 35.31% respectively.While the mass of the first,middle,and end knuckles of the topology optimized rear end pickup is reduced by 38.75%,18.63%,and 26.45%respectively,which meets the high temperature resistance and lightweight optimization objectives of the hub under-rank endpicker.Finally,the ADAMS virtual prototype simulation and experiment of wheel forging robot under-rank endpicker are completed.The simulation results show that the contact force of each knuckle of the under-rank endpicker is almost the same,which verifies the correctness of the force balance optimization design of each knuckle of the under-rank endpicker.The motion speed and angular velocity curve of each knuckle reflects the motion condition of each knuckle of the endpicker at different times and the contact condition with the forging,which is consistent with the previous motion analysis,and further proves the correctness of the motion analysis of the endpicker.The experimental results show that the under-rank endpicker is effective and has strong adaptive ability. |
