Study On Application Of Welding Technology And Repair Material With Trailing Peening

At present,rolling mill mainly is used in continuous conveying roller to link two adjacent procedure.It is directly related to the entire production line of production continuity and stability,which governs the production capacity of the production plant.The conveying roller bears hot and cold alternating because the conveying roller transporting the screw-thread steel is mostly cooled by water which can lead to fatigue damage and crack.At the same time due to the gravity and high temperature of screw steel,round bar and other products,etc,It is easy to wear and deform the material surface and causes the material damage.So there are a large number of conveying rollers to repair every year,which has greatly increased the cost.Repairing the damage and material is the favorable measures for the enterprise production cost control to enhance the production efficiency.The service life of the roller repaired with welding method is prolonged and the service time is similar to the new roller,which greatly reduces the production cost.However,the residual stress reduces the roller material life,which causes the crack of roll materials.Trailing hammering can eliminate the residual welding stress of welding roller and improve the fatigue strength of roller,reduce the non-uniform material and micro defects of welding roller surface chill layer,which improves the welding roller service life.The hammering device are used in the on the welding repair area of material qt500.The effects of the hammer force(wind pressure),hammering strike duration,the start time after welding and the hammer strike frequency factors service life of the roller after being repaired.The change of stress tested using static resistance strain gauge.With optical microscopy,the changes of the internal crystal are compared before and after hammer restoration;it were processed in the orthogonal experimental method to obtain the optimal peening parameters;Calculating the optimal hammering parameter,repair conveying roller material.The conclusion of the study are as follows:(1)Hammering QT500 roller material after welding can prolong the service life.When the hammer intensity(wind pressure)0.55 MPa,frequency 90 Hz.When it started 20 seconds after being welded after to proceed,,the service life of the material repaired is the longest at time of 25 seconds.(2)All the hammering factors can affect the service life of the roller material in the hammering repair method.With the increased value of impact hammer numerical factors,the service life of the roller material repaired are obviously improved.When the temperature reaches 500 degrees or higher in the welding region,the effectiveness of hammering treatment will be better.This is because after being heated,the yield point the material in this region is decreased and has better ductility,so the plastic deformation of the roller material is less and welding residual stress is eliminated more.(3)Experimental result is calculated and analyzed in the method of orthogonal experiment.The experimental results to obtain the hammer process parameters of the best effectiveness of the repaired roller with prolonged service life.