Drill Pipe And Tube End Upsetting Forming The Numerical Simulation Of The Process

Oil drill pipe is the important part of mechanical equipment in petroleum drilling industries, so it is requested to have the high intensity, high anti-pull and anti-fatigue properties. Research shows that fatigue life of drill pipe was influenced by the geometric shape in intermediate belt formed during the end upsetting process. So that optimize the end upsetting process and improve the performance of the geometric shape in intermediate belt can release the stress concentration and increase the fatigue life of drill pipe. Because of the complexity of end upsetting process, it is necessary to adopt appropriate deformation temperature, speed, blank volume and shape of tools to obtain the high quality product. Parameters that influence the end upsetting process and working procedure were studied in this paper, and the thermal-mechanical coupled rigid-plastic FEM was put forward to simulate the process of end upsetting for oil drill pipe.Firstly, process for end upsetting of oil drill pipe was analyzed and factors that influence the forming process were investigated. Aimed at grade G105Φ127×9.19mm oil drill pipe, parameters of end upsetting process were calculated and tools and working procedure for end upsetting were designed.Based on the working procedure and parameters of end upsetting process, the flow stress behavior of grade G105 steel (API standard) for oil drill pipe during hot compression deformation was studied by isothermal compression tests using Gleeble-1500 thermal-mechanical simulator. After being confirmed the validity of the results of hot compression tests and corrected the temperature increase because of the deformation heating, the constitutive equation of the flow stress about G105 steel was obtained by means of regression analysis in Matlab. The correlation coefficient is 0.9272 and it indicates that the regression equation is noticeable and has high precision in certain temperature range and strain rate range.The constitutive relationship obtained from the above-mentioned studies was used as the material model in the FEM simulation. Aimed at the grade G105Φ127×9.19mm oil drill pipe, FE model was established in software MSC.Marc and the process for the original end upsetting of oil drill pipe was simulated. Through analyzing the development of stress, strain, and temperature distributes, the rules of metal flow are described during the end upsetting process. The studies are significant for determining the parameters of the process and tools design.Because of the imperfection occurred during the simulation process for the original end upsetting, tools and working procedure were optimized and the product with good geometric shape was obtained. Comparison between the curve of the intermediate belt formed in the simulation and the ideal line was adopted to evaluate the geometric shape in intermediate belt.