Design And Optimization Of ROV-based Laser Cladding System End Cap

Laser cladding technology is a technology that can change the physical and chemical properties of materials.Its principle is to use the laser beam with high energy density to irradiate the material coated on the surface of the main body according to the designed scanning path under the protection of inert gas,so that the cladding material and the surface of the main body can melt and solidify quickly.Finally,it becomes a functional coating with metallurgical bonding characteristics,which can greatly improve the performance of the main surface.With the development of offshore platform and ship industry,the need for underwater additive is increasingly urgent,and underwater laser cladding technology has become another emerging field.In this paper,the end cap of the existing underwater laser cladding system depends on threaded connection,can only be used in one direction,high demand for gas cylinder,high material loss rate,the structure design,simulation,structure optimization and experimental testing are studied.According to the structural parameters of the existing cladding head,the structure of the end cover is designed.The structure is mainly composed of steel ball,valve seat,female end,sliding sleeve,liner,connector,limit ring,valve nut,cladding head,experimental bolt,spring regulator,clamp,check valve retaining ring,sliding sleeve spring,valve core,check valve spring,lining spring,O ring and so on.The structure of the check valve inside the end cover was simulated and analyzed by Fluent.Through the study of the dynamic characteristics of the check valve opening and closing process in the deep sea environment,it was found that with the increase of outlet pressure,the spool motion displacement and velocity fluctuation peaks decreased,the vibration range was smaller,the spool motion was more stable,and the dynamic characteristics showed an overall trend of attenuation oscillation.With the increase of spring stiffness,the spool displacement peak decreases and the fluctuation range decreases in the deep-sea environment,while the spool vibration period is shorter,which will lead to the increase of the peak speed.In the process of closing check valve in deep sea environment,with the increase of spring stiffness,the valve is completely closed for a shorter time,the maximum overdrive of spool displacement is decreasing,and the peak motion speed is increasing,that is,the impact force between valve core and valve seat is also increasing.In order to ensure the check valve has good sealing performance in deep sea environment,the spring stiffness is appropriate to choose 500N/m;Choose the spool cone Angle of 60° to 64°structure can effectively reduce the steady-state fluid power,improve the operability of the valve,increase its stability and reliability.According to ANSYS statics analysis,when the end cap is subjected to31.25 MPa external pressure and 12.5MPa internal pressure respectively,the maximum deformation occurs in the center of the internal cavity,which conforms to its stress law,and the maximum equivalent stress value is lower than the yield strength of 022Cr17Ni12Mo2 material,meeting the strength requirements.Through the nonlinear analysis of the O-ring at the cladding head,under the premise of meeting the requirements of working conditions,the compression rate of the precompressed O-ring is selected as 8%,and the compression rate is guaranteed according to the size of the gap between the inner wall of the cladding head and the parent end.When the leading Angle was 25° and the rounding Angle was 5°,the VonMises stress and contact pressure were the minimum.The maximum contact pressure of O-ring under internal and external pressure is 30.985 MPa and 42.894 MPa,which is higher than the pressure.Therefore,the designed structure and O-ring can meet the sealing requirements.Through the underwater experiment and the pressure barrel experiment,it is proved that the structure can be disassembled and assembled in the underwater axial direction,the sealing effect is good,the structural strength is high,the connection is reliable and can be used many times.Through the structural design and simulation optimization analysis of the end cap of the underwater laser cladding system,this paper provides the end cap structure with reliable connection,reusable,high strength,good tightness and simple operation for the underwater laser cladding system,reduces the requirements for gas cylinders and material loss,and provides quantitative reference for the research of the underwater laser cladding system.