Forming methods of LSAW steel pipe

LSAW (Longitudinal Submerged Arc Welded) steel pipes are produced using a specific forming method. Here are the main forming methods for LSAW steel pipes.

A comparative study of various forming methods reveals that the edge forming effects of the single-radius and double-radius methods are suboptimal, whereas the three-radius W-shape forming method produces significantly better results. Based on numerical simulation data, a new design approach for the forming process of medium-diameter welded pipes (Φ219x6) is proposed. The study includes the development of billet deformation and roll distribution diagrams, along with the detailed design of the structural dimensions of the first horizontal roll using the three-radius W-shape.

This research suggests a cost-effective design strategy that integrates empirical methods with numerical simulations. The proposed approach serves as a foundation for refining the design of welded pipe hole patterns, roll patterns, and forming processes. It also aims to enhance the overall quality of welded pipes and facilitates the shift from traditional empirical design techniques to a more efficient, simulation-driven methodology for welded pipe hole and roll pattern design.

In current engineering practice, the forming process and unit design of straight-seam welded pipes still largely rely on empirical design methods. A significant disadvantage of these empirical methods is that the rationality of the process and roll design can only be verified through production trials, leading to high costs and long lead times. This approach is becoming increasingly unsuitable in the fast-evolving market economy.

By utilizing elastic-plastic large deformation and contact nonlinear finite element methods, and employing advanced finite element software such as ANSYS, a more realistic three-dimensional model of the welded pipe forming process is developed. This model allows for the investigation of small-diameter welded pipe billets in both single-pass and multiple-pass forming processes. It provides insights into the changes in stress distribution, strain behavior, curvature, pressure variations, and leaning force throughout the molding process. Additionally, a three-dimensional stress and strain distribution map for half of the billet is created, offering detailed analysis of the deformation process.

The study also explores three different forming methods: the baseline constant single-radius forming method, downhill single-radius forming method, and downhill double-radius forming method. The effects of these methods, along with the billet wall thickness, on stress, strain, curvature, and pressure during the molding process are considered in detail.

LSAW pipe forming is inherently a complex process involving elastic-plastic large deformation and multiple nonlinear couplings. As a result, both theoretical and experimental research in this area have lagged behind engineering practice. Even with the application of finite element analysis, many challenges remain, and comprehensive numerical simulation research on LSAW pipe forming is still incomplete.