Research on Distribution Properties of Coating Film Thickness from Air Spraying Gun-Based on Numerical Simulation

Xiaopeng Xie,Yinan Wang

doi:10.3390/coatings9110721

Abstract

This work aims to study the influence of the spraying parameters on the spray flow field and coating thickness distribution during the air spraying process. The shaping air pressure and the target geometry have an important influence on the distribution of coating film thickness. This paper begins with a 3-D physical model of an air spray gun, in which unstructured grids were generated for control domain. A grid independency study was also carried out to determine the optimal number of cells for the simulations. Then the Euler–Lagrange method was used to describe the two-phase spray flow by establishing a paint deposition model. The numerical simulation based on the discrete phase model (DPM) and TAB model has been carried out. A reasonable assumption was proposed based on the analysis of the spraying process, so that the droplets were injected into the airflow at the position of the paint hole. The influence of the shaping air pressure on the air flow field and the coating thickness distribution was analyzed by changing the shaping air pressure. From the numerical simulation results, it can be concluded that the smaller the shaping air pressure, the more concentrated the coating. With increasing the shaping air pressure, the length of the coating film along z-axis gradually increases, the width along x-axis gradually decreases, and the spray area gradually increases. The paper ends with a numerical simulation and experimental study on planar vertical spraying, planar tilted spraying, and cylinder spraying. Comparisons and experiment results verify the validity and practicability of the model built in this paper.

Highlights

Thanks to the advantages of robot spraying, such as high efficiency, better service, and protecting workers from extreme working environments, spraying robots are widely used in industries, including automobile, furniture, and spaceflight industries
Demonstration and off-line programming are two common methods used in robot spraying
Demonstration is not flexible, and the spraying quality depends more on workers’ experience, while off-line programming can avoid such shortcomings. It goes like this: optimized objective function for best service quality is established according to the work-piece surface parameters and the model of coating thickness distribution and the spraying profile will be obtained through solving optimization problems [1]

Summary

Introduction

Thanks to the advantages of robot spraying, such as high efficiency, better service, and protecting workers from extreme working environments, spraying robots are widely used in industries, including automobile, furniture, and spaceflight industries. Demonstration is not flexible, and the spraying quality depends more on workers’ experience, while off-line programming can avoid such shortcomings. It goes like this: optimized objective function for best service quality is established according to the work-piece surface parameters and the model of coating thickness distribution and the spraying profile will be obtained through solving optimization problems [1]. Whether the model of coating thickness distribution can be calculated or not is vital for the planning of spraying profile and the improvement in spraying quality. Earlier researchers have adopted empirical formulas to simplify the spraying models, among which the infinite-range models include

Objectives

Results

Conclusion