Research On Micro-removal For Aluminum Clad Of Aircraft Skin By Robotic Grinding

In recent years,the civil aviation industry develops rapidly.The number of civil aircraft is increasing day by day,and the demand market for civil aircraft continues to rise.Aircraft,as a fast and convenient long-distance means of transportation,has gradually come into the public’s view from the past high-end and expensive consumption,and the safety of flight has attracted wide attention.Aircraft skin is a component that forms the shape of the aircraft,maintains the good aerodynamic performance of the aircraft and bears and transfers the load,which is directly related to the flight performance and life of the aircraft.There are certain particularity and complexity in the working environment of aircraft skin,which makes aircraft skin easy to shrink and deform,accelerate aging,and poor airworthiness.Therefore,there are stricter requirements on the performance of aircraft skin.Aluminum alloy is often used in civil aircraft skin,which is usually corroded in the process of transportation and storage.It is generally coated with a layer of pure aluminum with a thickness of about 65-75μm on the surface of aluminum alloy plate(usually called aluminum clad).The aluminum clad has the effect of corrosion resistance on the aluminum alloy inside,but the mechanical strength is low,so it is necessary to realize the micro removal of aluminum clad in the manufacture of aircraft skin.At present,aircraft aluminum coating grinding mainly depends on manual grinding.It is difficult to accurately control the removal allowance and grinding position,the workpiece surface consistency is poor,and the grinding efficiency is low and the working environment is harsh.Therefore,more mature equipment and technological means are urgently needed to replace manual grinding.The robot has the advantages of strong versatility,stable performance,flexibility and high intelligence.Combined with grinding process,precision grinding can be realized.Based on the background of the horizontal topic "Design and process verification of the end actuator for intelligent grinding of civil aircraft skin",this paper carried out the research on the process of robot grinding microremoval of aircraft skin aluminum.The main research contents of this paper are as follows:(1)According to the processing characteristics of industrial robots,the processing characteristics of materials and the process requirements of the workpiece,the robot grinding platform system was established.The system realizes the functions of constant force grinding,automatic generation of grinding trajectory,real-time collection of grinding force and motion position data,dust collection,anti-bonding and so on.(2)The shape of abrasive particles was simplified reasonably,and the material removal mechanism was analyzed by using elastic-plastic mechanics and grinding theory.The material removal function model was established based on Preston equation,and the main grinding process parameters affecting the material removal depth were determined.Using ABAQUS software,the finite element simulation of grinding process was carried out,and the simulation results of the influence of single factor process parameters on the machining process were analyzed.The influence law of grinding pressure,feed speed,tool speed and abrasive particle size on the material removal depth was revealed.(3)Based on the self-built robot grinding system platform,a single factor experiment was designed and carried out to study the influence law of main process parameters on the material removal depth,and to verify the reliability of the model.The correlation between the main process parameters and the material removal depth was determined by range analysis method.(4)The orthogonal test was designed and carried out.The range analysis method and variance analysis method were used to study the influence degree of the main process parameters on the material removal depth,and the optimal combination of process parameters was determined.Based on the orthogonal test data,multiple linear regression method was used to establish the prediction model of the relationship between grinding pressure,feed speed,tool speed,abrasive size and material removal depth,and the significance test was carried out.Finally,the optimum process parameters were selected to carry out the grinding test on civil aircraft aluminum coating to verify the consistency and stability of the processing quality,and the processing of aluminum coating was completed.