Forming Process of Thin-walled Welded Steel Pipe

1. Downhill forming method

Downslope shaping of welded steel pipe equipment can significantly reduce edge extension.

2. Increase the middle extension of the billet

During the forming process, the reduction of the opening hole pattern increases, making the gap between the upper and lower rollers slightly smaller than the thickness of the billet. The middle part of the billet is micro-calendered to make the middle extension slightly larger to reduce the relative extension of the edges. If the middle extension is greater than the edge extension, the outlet will bend upward. If the middle extension is smaller than the edge extension, downward bending will occur.

The central extension increases the deformer of the forming machine, increases power consumption, causes serious wear of the rollers, and easily damages the equipment. When the tube blank and the roller surface slide relative to each other, roller marks and scratches are likely to occur.

3. Increase the length of the deformation belt

If possible, increase the number of frames involved in the deformation, i.e. increase the length of the deformation zone and reduce the deformation between two adjacent frames. Since the edge extension is proportional to the square of the frame height, the edge extension can be significantly reduced.

4. Increase the roller diameter

Increasing the roller diameter means increasing the length of the deformation zone of the frame. The edge extension is inversely proportional to the length of the deformation zone of the weld bead. Where possible, edge extension can be reduced by increasing the roll diameter as much as possible.

5. Reduce the distance between racks

When the distance between frames is large, the cumulative edge extension of each frame must be compressed and absorbed by the last few frames, which can easily cause expansion. Shortening the distance between frames essentially increases the number of frames, which can be compressed and absorbed at any time, thus improving the forming conditions. However, the distance between frames cannot be too small, and sufficient operating space must be left.