Study On The Application Of The Mixing Tank For Second Generation Cataphoretic Coatings Of High Throwing Power For Cars

With the rapid development of automobile industry in China,more than 28 million cars have been produced in 2016.Automobile painting is the process of high energy consumption,high pollution and high material cost in automobile production,and it is urgent to solve these thorny problems with some material that is energy saving,environmental protection and low cost.Electrophoresis process is the key process of antisepsis,and the latest trend is reducing material cost of the vehicle production through the second generation cataphoretic coatings of high throwing power which can meet with silane,zirconium,such as phosphate as pretreatment and water from the new technology of energy conservation and environmental protection coating,etc in supporting demand.The resin system of the second generation high throwing power cataphoretic coatings is different from with the normal cataphoretic coatings,and the parameter control scope and solvent system is different.Therefore,the line using ordinary cataphoretic coatings that would switch the second generation cataphoretic coatings of high throwing power,usually abandons the old type cataphoretic coatings of full groove,and uses the new cataphoretic coatings.However,this method is expensive and requires a long production downtime.Therefore,how to adopt the low cost and no production switching mode to complete the switch of new old model cataphoretic coatings becomes the focus of the research.This paper focuses on the feasibility of switching from the PN310 of ordinary cataphoretic coatings to the PN1510 F of the second generation cataphoretic coatings of high throwing power through the way of mixing tank.A series tests are carried out carried out for the body plate,the pretreatment process and the surface paint technology that are being used in the current production line or may be used in the future.And the existing problems are improved and verified.By mixing the new and old electrophoresis with different ratios,the paper calibrates the parameters of the mixed bath,analyzes the change trend of the bath under different mixing ratio,and makes electrophoresis experiment board,and detects the key performance indexes of the electrophoresis coating and makes corresponding analysis.Based on the analysis of the experimental results,the feasibility of mixing groove switching is determined and the control scheme of the bath parameters under different mixing ratio is developed to ensure that the physical quality meets the product requirements during the switching process.Based on the experimental results,the switching is performed on the production line and the effect is tracked.The experimental results show that the performance of the second generation of cataphoretic coatings of high throwing power PN1510 F on the three kinds of plates(cold-rolled plate,galvanized plate,magnesium alloy plate),two kinds of pretreatment process(ternary zinc phosphating and no phosphorization)and two kinds of topcoat technology(traditional solvent type,water free coating)used for the production of car body in the supporting production line could meet the requirements.The formulation of the electrophoretic material needs to be improved when the pretreatment system of no phosphorization is used.In the switching process of mixing bath,the bath parameters need to adjust the range of control according to the replacement rate.When the 50% new type of electrophoretic paint is mixed,the change of the parameters has an inflection point.Therefore,the switching process under the replacement rate should be monitored and make adjustment in time according to the change of the parameters.The mixing tank experiment shows that in the construction performance,there is no risk of resolubilization of the car body within 10 minutes of line stoppage.But in the dry state,the production line could not stop more than 5 minutes,otherwise the body will have related defects.But this can be alleviated by increasing the temperature and humidity in the dry area of the production line.In addition,the body degreasing state should be strictly controlled in the process of mixing,so as to ensure the cleaning of the body oil pollution and avoid the production of the body shrinkage defects.The practical application results show that the quality of the whole car body is stable during and after the switching process of the new and old bath.The thickness of the vertical membrane of the outer panel is reduced by 5?m,the thickness of the horizontal mask decreases(2~4)?m,the thickness of the inner membrane decreases(2~3)?m,and the thickness of the inner cavity is basically unchanged.