Spiral submerged arc welded pipe coil forming pipe diameter overrun causes

In the spiral submerged arc welded pipe coil molding production process, one of the common molding process defects have pipe diameter overrun. What is the cause of this defect?

Strip steel “crescent bend” is the main factor causing the wrong side. In the production process, in the case of the molding angle remains unchanged, in order to ensure that the pipe diameter is appropriate, can only be eliminated through the wrong side of the “crescent bend”.

Process parameters are not appropriate, resulting in uneven deformation of the delivery edge and free edge, the difference is too large will lead to wrong edge.

Forming seam bite too tight. Such as the strip run, will make the strip in the molding machine inlet angle increases, prompting the rear bridge angle is large, so that the molding seam bite is too tight and caused by the wrong edge.

Welding pad roller position is not correct. Welding pad roller is generally biased toward 1 # molding roller 10 ~ 15mm, eccentric distance is too small is easy to cause the wrong side, eccentric distance is too large is easy to cause the wrong side.

Welding bias is also a factor that causes wrong edge. Serious welding deviation over a long distance will lead to wrong edge or open seam, so it is necessary to control welding deviation.

Poor delivery of the strip will cause the strip to run off, so that the edge of the strip extrusion thick, resulting in wrong edge.

Uneven width of strip or bad condition of strip edge will easily cause wrong edge.

Strip steel surface is not flat, there are large waves or hard bending are very easy to cause wrong edge, so try to improve the leveling effect.

Pre-bending roller roller type is not suitable or the strip ends of the pre-bending amount is not appropriate, are easy to cause wrong edge, so to effectively adjust the pre-bending amount.

Therefore, in order to effectively control the pipe diameter and wrong edge in the appropriate range, we must minimize the “crescent bend” of the strip, strictly control the quality of the strip to the head, carefully control the delivery of the strip, to avoid artificially caused by the “crescent bend”.