Influence of Processing Parameters on Coating Removal for High Pressure Water Jet Technology Based on Wall-Climbing Robot

Abstract

Featured Application: The study shown in this manuscript helps to guide the further application of a wall-climbing robot for the shipbuilding industry.Abstract: The shipbuilding industry is very important for many countries. As an essential process in the shipbuilding industry, surface preparation (or coating removal) is gaining more and more attention. The traditional process used for ship hull coating removal is a sand-blasting process, which is harmful to the environment and inefficient. Recently, high pressure water jet technology has been developed to replace the traditional sand-blasting process. However, there are still many technical problems to be solved. In this paper, one wall-climbing robot was developed to remove coating based on high pressure water jet technology. Coating removal experiments under various experimental conditions were carried out and the corresponding coating removal rate for each case was obtained and compared. In addition, numerical simulation based on Fluid software was conducted to observe the water jet process more visually. Results show that the processing parameters, including the water pressure, travelling speed, inclined angle, and stand-off distance, can greatly influence the coating removal effect. The optimal processing parameters are obtained to guide the application of the high pressure water jet technology based on the designed wall-climbing robot for the shipbuilding industry.Many cleaning methods have been proposed and applied for hull cleaning in the last several decades. The most widely used traditional ship surface cleaning method is called sand-blasting [2], which generates a profile in micrometer-range by accelerating a sand-basting media through a nozzle with compressed air. However, this sand-blasting method has an obvious disadvantage: the concentration of soluble substances on the treated surface after sand-blasting is very high, and thus an extra cleaning process should be added before recoating [3]. Besides the sand-blasting method, there are also other surface preparation methods, such as high temperature oxidation [4], electrochemical method [5] and laser coating removal method [6]. The former two methods are not environmental friendly, and they both require large energy consumption, while the latter can induce thermal and physical damage to the work-piece due to excessive heat produced by the laser. Recently, hybrid laser-water-jet technology was proposed to yield high material removal rate without thermal damage [7], the energy consumption was also reduced but the costs of applying the two technologies are quite expensive.According to the literature mentioned above, the challenges faced during ship hull cleaning can be addressed as: How to minimize the energy consumption? How to realize environmental protection? How to enhance the cleaning efficiency? For the first two requirements, high speed water jet technology has been introduced recently as a promising substitute method [8]. During the water jet process, the potential energy of the high pressure w...

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