The forming process of thin-wall welded steel pipe

1. Downhill forming method

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

2. Increase the intermediate extension of the billet

During the forming process, the reduction of the hole pattern is increased, so that the gap between the upper and lower rolls is slightly smaller than the thickness of the billet. The middle part of the billet is slightly calendered to make the middle part extend 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, and if the middle extension is less than the edge extension, then downward bending will occur.

The central extension part increases the deformer of the forming machine, increases the power consumption, causes serious wear of the roll, and easily damages the equipment. When the tube blank and the roller surface slide relatively, it is easy to produce roller marks and scratches.

3. Increase the length of the deformation zone

If possible, increase the number of frames involved in the deformation, that is, 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 roll diameter

Increasing the roll diameter means increasing the length of the deformation zone of the frame. The edge extension is inversely proportional to the length of the weld bead deformation zone. When possible, increase the roll diameter as much as possible to reduce edge extension.

5. Reduce the distance between the racks

When the distance between the 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. Frames can be compressed and absorbed at any time to improve the forming conditions. However, the distance between the frames cannot be too small, and there must be enough operating space.