Optimization Of ERW Welded Pipe Roll Groove Process And The Study Of Cracking Phenomenon

With the rapid development of welded pipe production technology,it is widely used in the national economy,the steel pipe used to transport the fluid is used as the link to connect the equipment,which is widely used in the construction water supply,drainage,chemical industry,petroleum and other fields.Although steel-plastic composite pipe has been widely used in domestic water supply pipe system,welded steel pipe is still widely used in fire water supply pipe system,among them,ERW welded pipe is the main one,in the field operation,the main joint mode of two welded pipes is clamp type,also known as groove type,compared with wire connection,flange connection and welding connection,clamp connection is more convenient and efficient to disassemble.The groove on the welded pipe is machined by a rolling groove machine,due to the great difference in microstructure and mechanical properties between the weld of the welded pipe and the base material,the end of the pipe is subjected to intense rolling in the grooving process,there will be weld cracking in serious cases,reworking not only increases production costs,but also to the construction application caused difficulties and inconvenience,in recent years,the phenomenon of weld cracking is common,therefore,it is also the top priority to study the solution of weld cracking.In this thesis,the ERW welded pipe of Q195 steel was taken as the research object,and on the basis of the original roll groove processing technology was optimized to explore the criterion of weld cracking and the process parameters affecting the criterion,and the following research was conducted by means of mutual verification between test and finite element simulation:To analyze the stress and plastic deformation in the rolling groove processing process according to the cracking problems in the actual production of enterprises,thus the process parameters of the rolling groove are optimized.According to the actual working conditions,the parameters that have great impact on the weld are respectively the pressure amount and speed of each turn and the initial position of the pressure,because the welding residual stress has direct influence on the weld strength,this factor is also analyzed as one of the parameters.A test scheme for optimization of rolling groove process parameters was developed,and the residual stress was measured and calculated on site.The finite element software Abaqus was used to simulate the welding and rolling process,and the accuracy and feasibility of the simulation results were verified by the test results.Through the stress analysis of rolling principle,it is concluded that the groove is the tangential stress at the weld after the compression decomposition,and the maximum tangential stress value is taken as the index as the cracking criterion,and then the relationship between the maximum tangential stress at the weld and the welding residual stress,the initial position of rolling,the number of rolling laps and the rolling feed is analyzed.Through orthogonal test and range of each factor,the optimal process combination and the main and secondary order of influencing factors were obtained,Is the initial rolling position,the rolling feed scheme and the number of rolling laps.