The Deformation And Vibration Simulations Of Drilling Robot When Suffering Drilling Forces

Robotic drilling has been widely applied in aviation manufacturing field, but being limited to the series structure, the stiffness of system is relatively insufficient, when suffering drilling forces, the end of robot will vibrate easily, even chatter occur, which will affect holing accuracy and quality. Here the research of robotic drilling process, turns to the analysis of robotic linkage dynamics, which takes drilling forces as external load, builds related mathematical and simulation models, analyzes the holing effects, and conducts the following 4 aspects:Firstly, extracts some parameters, including the length, mass, center of mass of robotic arms; builds 3D models of robot system, defines robotic link coordinate system using the prepositive D-H method model, deduces robotic Jacobian matrix by vector integration method.Secondly, considering the flexibility of robotic joints, simplifies one joint as a torsion spring with stiffness and damp, deduces robotic system dynamics equation with joint flexibility considered using Lagrangian method, and analyzes the system stiffness in different postures.Thirdly, analyzes the structure of general twist drill, combines the experimental results, builds the mathematic model of drilling forces. Considering the end of robot will vibrate spatially when suffering external force, improves the drilling force model with the influence of twist drill throb spatially on drilling forces considered.Finally, combines the robot dynamics model and drilling force model, builds integral feedback simulation model in Matlab/Simulink. In simulation, sets several postures, keeps the same height of twist drill and feed direction; analyzes the dynamic changes of robotic system, analyzes the holing effects in different postures from the runout of axes; conducts simulations in one posture with different combinations of rotation speed and feed speed, according to the fluctuation characteristics of thrust force, analyzes stability of drilling process, and calculates vibration frequency of the system.According to the simulation results, if keeps the same height of twist drill and feed direction, the holing effect in different postures with the same drilling parameters, and when the deviation of holing are too large to suit to drilling; distinguishes the system stability when drilling in same posture by different parameters, and when the rotation speed higher, stability better.The system stability affects the hole effect, when robotic drilling, selecting appropriate posture, rotation speed and feed speed is important to improve the holing quality and efficiency.