| The leakage of emulsion in hydraulic support not only reduces the reliability and efficiency of the system,but also causes serious pollution to the environment.The application of pure water medium hydraulic technology has advantages that emulsion does not have in cleaning,environmental protection,and renewable aspects.However,the low viscosity and strong corrosion of the pure water itself make the sealing performance and corrosion resistance of the pure water hydraulic cylinder far worse than that of the traditional oil medium hydraulic cylinder,which is more likely to cause the leakage and corrosion aging of the hydraulic cylinder.In this paper,the piston seal and anti-corrosion technology of pure water column hydraulic cylinder of hydraulic support were taken as the research objects.Through a series of work such as theoretical analysis,simulation design,sample preparation and experimental verification,the new drum structure seal and mountain structure seal for the piston of pure water column hydraulic cylinder were developed,and a set of feasible surface treatment process scheme of pure water column hydraulic cylinder was obtained.Specific work is as follows:(1)Based on the fluid gap flow theory,the equation of pure water viscosity varying with temperature and pressure was derived,and the pure water viscosity at different temperatures under hydraulic cylinder pressure was calculated.The formula of water film thickness and net leakage of internal and external stroke of hydraulic cylinder was derived by Reynolds equation.The contact pressure curve on the main sealing surface is obtained by ANSYS Workbench software,and the pressure gradient on the main sealing surface was calculated by taking the equal spacing point.Combined with the viscosity and pressure gradient data,the water film thickness and net leakage of each reciprocating hydraulic cylinder were calculated to analyze the factors affecting the sealing performance.(2)In view of the poor lubrication of pure water,the structure of seals suitable for pure water was studied.The structural optimization design of drum seal structure and mountain seal structure was carried out by orthogonal test optimization design method.The Von mises stress and contact stress of drum seal structure and mountain seal structure were evaluated and compared by ANSYS Workbench software,so as to obtain the structural parameters of drum seal structure and mountain seal with the most superior sealing performance.Then,the sealing performance of the new drum seal structure and the new mountain seal structure under different working conditions was compared,and finally it was shown that the mountain seal structure was more suitable for pure water hydraulic cylinder under low medium pressure,and the drum seal structure was more suitable for pure water hydraulic cylinder under high medium pressure.(3)The sample preparation and performance test experiments of the two new structure seals were carried out,and the experimental scheme was formulated according to the relevant standards of the coal industry.The performance test bench of the seals was built,and the performance tests of the two developed seals were carried out.Through a series of tests,the results showed that the two new seal rings can be effectively sealed when the pure water hydraulic cylinder works,and have qualified service life.(4)The advantages and disadvantages of common surface treatment processes for hydraulic cylinders were compared and analyzed.Laser cladding coating was selected as the anti-corrosion process of hydraulic cylinders in pure water medium,and the cladding coating material on the surface of hydraulic cylinders was selected combined with the use cost and corrosion resistance.Referring to the processing scheme of traditional oil medium hydraulic cylinder,the experimental samples under different processing schemes were produced.Then the samples were electrochemically tested,and the corrosion resistance of the samples under different process schemes was compared and analyzed.The sample with the best corrosion resistance was found,and the feasible scheme for surface processing of pure water hydraulic cylinder was proposed. |
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