Study On The Key Technology Of Laser Cladding On Tri-eccentric Butterfly Valve Disc Sealing

Tri-eccentric butterfly valve has been widely used in water conservancy,petroleum,chemical industry,metallurgy and shipbuilding in recent years.It is a new butterfly valve with the advantages of zero seal friction,zero leakage,high temperature and high pressure resistance.In order to improve the the sealing surface abrasive resistance of the trieccentric butterfly valve and prolong its life,it is generally necessary to melt or weld a stainless steel or cobalt-based hard alloy strengthening coating on the valve sealing surface.This paper focuses on strengthening the WCB tri-eccentric butterfly valve sealing surface,proposing selfassembled iron-based self-fluxing alloy powder cladding coating and the trajectory planning algorithm for tri-eccentric butterfly valve sealing surface,which will replace the traditional surfacing welding fusion.It is expected to significantly enhance the the valve sealing surface wear resistance,save material costs and shorten processing time.The main achievements of this paper are as follows:(1)Based on the robotic fiber laser processing station equipment and a dedicated square spot laser cladding head,taking laser cladding test with self-assembled iron-based self-fluxing alloy powder.The experimental results show that the powder feeding rate,laser power,and scanning speed have a significant influence on the macroscopic morphology of the laser cladding iron-based alloy layer during single-pass laser cladding.The aspect ratio of the cladding increases with the scanning speed and laser power.The dilution rate of the cladding layer increases with the increase of the increase of the scanning speed,and decreases with the increase of the laser power.The effect of the laser power on the dilution rate is better than that of the scanning speed.(2)Aiming at the tri-eccentric butterfly valve shape,designing a universal plate fixture and finishing the trajectory planning algorithm for the laser cladding of the triple eccentric valve plate sealing surface under the conformal taper cone fixture and plate universal fixture.Comparison of trajectory planning algorithms to illustrate the versatility and accuracy of the flat-type universal fixture combining the six-axis robot + rotary table combined optical fiber laser processing station can simplify the trajectory planning of the sealing surface of the laser cladding triple eccentric valve plate(3)Analyzing the microstructure of the laser cladding layer.The test results show that the cladding layer is roughly divided into three parts: the cladding layer zone,the bonding zone and the matrix heat affected zone from the upper part to the lower part.The microstructure of the cladding layer includes equated crystals,dendritic crystals,columnar crystals,cell crystals and planar crystals from the surface of the cladding layer to the substrate.XRD diffraction analysis showed that the phase composition in the cladding layer was mainly ?-Fe,TiC,and Fe3 C.(4)Analyzing the effect of laser power,scanning speed and other process parameters on the hardness,wear resistance,and cladding residual stress of the cladding layer.The test results show that the micro hardness of the cladding layer under various parameters is relative to the matrix.Larger increase,the average micro hardness is 619.0HV0.2,and its micro hardness is about 3 times that of the substrate.Under the same conditions,the friction coefficient and wear amount of the cladding layer are far less than the friction coefficient of the substrate.And wear,and the amount of wear of the substrate is approximately 2 times that of the cladding layer;in the direction of the parallel laser scanning,the residual stress on the surface of the cladding layer is tensile stress,and the residual stress on the surface of the cladding layer is greater than that of the cladding layer.The residual stress in the middle of the surface is large,and the maximum residual stress is about 670 MPa.