Forming Technology of Thin Wall Welded Steel Pipe

1. Downhill forming method: Downhill 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 pass pattern is increased, so that the gap between the upper and lower rollers is slightly smaller than the thickness of the billet. The middle part of the billet is micro-calendered, so that the extension of the middle part is slightly larger, to reduce the relative extension of the edge. If the middle extension is greater than the edge extension, the outlet bends upward, and if the middle extension is less than the edge extension, the outlet bends downward. The central extension increases the deformer of the forming machine, increases power consumption, causes serious wear of the rolls, and easily damages the equipment. When the tube is 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 side extension is proportional to the square of the frame height, the side extension can be significantly reduced.

4. Increase the diameter of the roll: increasing the diameter of the roll means increasing the length of the deformation zone of the frame. Edge extension is inversely proportional to the length of the bead deformation zone. Where possible, edge extension can be reduced by making the roll diameter as large 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 inter-frame distance essentially increases the number of frames, which can be compressed and absorbed at any time, thus improving the shaping conditions. However, the distance between the frames cannot be too small, and there must be enough room for manipulation.