Font Size: a A A

Spraying Trajectory Planning And Coating Quality Research For Complex Surfaces

Posted on:2022-07-30Degree:MasterType:Thesis
Country:ChinaCandidate:P CaoFull Text:PDF
GTID:2511306494992959Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
The emergence and development of spraying robots and spraying technology provide more possibilities for the automated spraying of complex curved surfaces such as aircraft skins.At this stage,most spraying robots realize spraying trajectory planning through manual teaching programming.Although multiple teaching can eliminate uncertain factors in the teaching process,the programming efficiency is low,the trajectory accuracy is poor and only suitable for simple curved surfaces.With the rapid changes in product structure and market demand,in the face of various CAD models with unknown complex curved surfaces,under the premise of ensuring coating quality and spraying efficiency,this paper proposes a research based on the surface characteristics of the curved surface combined with the coating quality Realize an efficient,accurate and flexible spraying trajectory planning method.The main research contents are as follows:(1)Propose an implementation scheme for reconstruction of complex surfaces with unknown models.The point cloud data of the object is obtained by scanning with a three-dimensional photographic scanner.The point cloud data preprocessing algorithm is studied.The point cloud data after noise reduction,smoothing and simplification is further processed by triangulation,meshing and surface processing,and then the three-dimensional model of the object is obtained.The high-precision three-dimensional model obtained by surface reconstruction is the basis for subsequent trajectory planning.(2)Solving spray gun spray trajectory based on tool processing trajectory.Analyze the CNC machining process based on the known three-dimensional model,set the tool,cutting,and process parameters in sequence,program the multi-axis milling processing path,optimize,edit and simulate the three-dimensional processing dynamics,and use uniform arc division to divide the processing path points Perform boundary processing.Comparing the similarities and differences between tool cutting and spray gun spraying,using NURBS curve and surface theory,parameterized processing of node vectors,inverse calculation of control vertices and weight factors,and fitting the surface where the tool processing track points are located.Then determine the normal vector of the tangent plane of the processing trajectory point on the curved surface,and combine with the optimized spray gun height to obtain the spray gun spray trajectory point.The normal vector of the tangent plane of the trajectory point can determine the spray gun’s posture when it reaches the spray trajectory point.(3)Coating quality research for the optimization of spraying process parameters.According to the material characteristics of the aircraft skin and the complex environment of the working space,the coating system and spraying process flow of the aircraft skin surface are determined.Based on the elliptical double β model,a plane coating thickness deposition model was established,and the effect of spraying rate and overlap width on coating uniformity was studied.The optimal spraying rate and overlap width were solved by establishing a spraying process parameter optimization model.A free-form surface coating thickness deposition model was established,and the effects of spray gun height,sweep rate,and trajectory curvature on the uniformity of the coating were studied.Under the premise of the optimal overlap width,the spray gun height and the spray rate are jointly optimized based on the trajectory curvature,and the best spray gun height and spray rate corresponding to each spray trajectory point are obtained.(4)Research on offline programming and simulation experiment of robot spraying trajectory.According to the known spraying trajectory points and their corresponding spray gun posture,spraying rate and spray gun height,the offline programming system is used to program the spraying trajectory of the robot and simulate the spraying trajectory.Spraying experiments were carried out on plane components and aircraft skins respectively.The experimental results verified the feasibility and correctness of the spraying trajectory planning method combined with coating quality research proposed in this paper.
Keywords/Search Tags:Aircraft skin, Robot spraying, Surface reconstruction, Trajectory planning, Coating optimization
PDF Full Text Request
Related items