| Due to their high hardness,high temperature resistance,corrosion resistance,low density and other characteristics,carbon fiber reinforced plastic(CFRP)and its alloy laminated material are widely used in large components in aerospace,national defense and other fields.There is always some defects such as burr,tear,etc,which can reduce the machining quality of the hole and even cause parts scrapped seriously,when the hole of typical difficult to cut materials was processed by traditional drilling technology.Helical milling technology has the advantages of small cutting force,low cutting heat,easy chip-removal,etc,which can significantly improve the efficiency of making hole and quality of machining,and has become the key technology of high efficiency making hole for difficult-to-cut materials.Currently,the existing problem is its large volume and weight for the helical milling end-effector of the current mainstream,as requires higher power and stiffness of the multi joint industrial robot.It is not only consume power,but also effect the form and position accuracy of drilling the hole.In order to solve this problem,a kind of lightweight helical milling end-effector is presented.The main research contents as follows:(1)It is proposed that the overall design plan for the lightweight helical milling end effector includes the main parameters design,the overall design and working process of devices,which is got by the requirement analysis for the end-effector with the constraints of shape and size.The structure design for the end actuator is mainly composed of the structure design of the working device,the structure design and check of the eccentric adjustment device of planetary reducer,the structure design and check of the power source.The weight of this end actuator is reduced by about 3/5 that is compared with the existing end actuator of the double eccentric sleeve structure,which is obtained by the improvement and innovative design of structure,under the same processing capacity.It is showed that the motion law for end-effector that doesn't have the motion interference meets the requirements of the helical milling motion by the simulation analysis of the movement of helical milling end-effector.(2)The structure of the supporting sleeve and the base of the guide rail positioning system whose weight and volume are larger in the accessories for end-effector is designed to be more lightweight ones,using the topology optimization method.The finite element model of the optimal design is established in HyperMesh,with the optimization goal is to minimize the volume.Topology optimization is used to obtain the optimal layout of the material in the design area.And then the optimized geometric model of the supporting sleeve and the base is built by the analysis of topology optimization results.It is obtained that the weight of the optimized supporting sleeve and base is respectly reduced by 26.7% and 25%,and the weight of the overall system is reduction of 18%,by the evaluation of structural optimization.(3)It can be seen that the structural strength and deformation both meet the running requirements by the building of finite element model of overall system for helical milling end-effector and the static analyses for the key parts;Furthermore,it is concluded that the low order natural frequency is much higher than the frequency of rotation and revolution in the overall system,which can be used to attest that the resonance can't be occurred and the requirement of the vibration is satisfied in device by the modal analysis of the overall system;Besides,the resonance will be occurred in the overall system when the external exciting frequency and its low order natural frequency of one order and two order work near the resonance,the device should be avoided in the external excitation frequency of work. |
PDF Full Text Request