| With the advancement in science and technology,people demand is more and more high for quality of seamless steel pipe,which puts forward relatively high requirements for its production process and production equipment.The same production equipment and the different process can roll out widely different quality of the steel pipe.In order to save the cost of enterprises,we do our best to optimize the existing process parameters without changing the equipment,which can improve the quality of steel pipe.It has always been a problem that enterprises attach importance to.In this paper,I take the full floating mandrel rolling process in Baoshan Steel Co.,Ltd.(Baosteel)as the research object,mainly to reduce horizontal wall thickness uneven and"bamboo" phenomenon of the seamless steel pipe,which is two major quality problems.By utilizing ABAQUS finite element software to simulate its rolling deformation process,to explore technique of metal in horizontal and vertical flow of steel pipe in the rolling process The parameters of hole type and process are modified by orthogonal test,to change the flow of metal and reduce the problem caused by uneven metal flow.The main research results of the thesis include:(1)In order to facilitate the optimization of the parameters of hole type and process,ABAQUS need be secondary development by using python language,and a set of all-floating mandrel continuous rolling simulation system was established,which included the establishment of rolling rollers,rolling parts and the mandrel and the output of Mises stress,equivalent plastic strain and model column coordinates in the rolling process.By comparing calculated value of the simulation and the theoretical value respectively,the correctness of the simulation system is illustrated.(2)The results show that the reduction of diameter and wall thickness of the steel pipe are the largest in the first stand(especially top of the hole)and a large horizontal widespread is produced at the roll-gap in the continuous rolling process.The the temperature of part of contact with the rolling tool is lower than the other parts,and the temperature decrease of the steel pipe in the roll-gap position is the slowest(the first stand is the most obvious).The steel pipe in the continuous rolling process is found that the value of the equivalent plastic strain from the top of the hole to the roll-gap gradually decrease.The uneven distribution of the temperature and equivalent plastic strain of the steel pipe along its cross-sectional is one of the reasons for the uneven wall thickness.(3)Using post-processing plug-in of column coordinate output in the simulation system to obtain the steel pipe head,middle and tail wall thickness uneven rate is 10%、8.5%and 11.17%respectively.The maximum outer diameter error of the head,middle and tail comparing with design value of the steel pipe is 3.95%,3.59%and 2.96%respectively.(4)In order to reduce the phenonmenon of "bamboo joint" and the unevenness of the horizontal wall thickness of the steel pipe in the whole floating mandrel process,it regard uneven wall thickness and overall diameter error as the objective function and use the basic methods of orthogonal experimental design to optimize the hole parameters(eccentricity,departure angle,and transition radius)and process parameters(rolling friction coefficient).Analysis of range need to be performed for the first three stand,to select the optimal hole and the process parameters.the simulation It is concluded that wall thickness unaverage rate of the steel tube head,middle and tail steel tube are decresaed by 5.5%,1.33%and 7.42%respectively,and that the maximum error of the outer diameter of the head,middle and tail reduce 1.44%,0.98%,and 0.46%respectively. |
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