The method for determining the profile of large diameter pipes and the optimal technological mode during calibration-bending in the weld zone

Abstract

The article presents the results of finite-element modeling of the local calibration-bending process of large-diameter pipes in the weld zone with control of the dynamics changes in the geometry of the inner and outer surfaces of the workpiece, the base diameter, the total deformation of the perimeter and ovalization of the contours. The author has developed the technique of determining the coordinates of surface grid nodes based on an algorithm implemented in a special LUA-program for the QForm complex. The developed modeling technique allows us to determine the optimal working stroke of the tool and other parameters of the local calibration of the tube billet to minimize its degree of ovalization. An example of the implementation of the local calibration method and the predicted change in the geometry of the contour of the pipe billet with diameter φ1420×40 made of K60 steel with the initial shape defects after welding is given. The technical implementation of the method of local correction and prediction of the tube billet profile is complemented by the possibility of editing it by expansion. Improving the accuracy of geometry in the end zones of pipes will directly increase the possibility of high quality butt-welding during installation of pipeline systems.

Modelling of the sheet forming while 3-roller bending process

“…Ovalization tolerance of LDT is within 3-5 mm range for underwater pipeline according to DNV standard [12]. Despite using expanders [13,14], specifications for welded tubes always have ovalization tolerances for the cross-section shape. Known solutions [15,16] which define regimes of tube billet forming when using 3-roller bending mills mostly consider deformation zone structure as symmetrical with application of load to bending roller in the middle of its contact surface and with bearing of billet on lower bearing rollers.…”

Calculation and experimental technique for evaluating the parameters of the contact interaction of a strip billet with a roll tool in the ERW mill lines

“…Thereby, the contact interaction between tubular billet and deformation tool should be examined. Interaction of a tubular billet with deformation tool is a decisive factor in determination of power and kinematic parameters of tubular billet forming process [20][21][22]. This interaction occurs along the contact surfaces, where controlled variation of tubular billet geometrical parameters and all technical parameters takes place.…”