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Piercing quality and control of seamless steel tube
- Jul 31, 2018 -

The quality of piercing rough seamless pipe has a great influence on the quality of seamless steel tube.The poor quality of piercing rough seamless pipe is mainly manifested in the defects of uneven wallthickness of pipes, internal dismantling and external folding. 

1 The main causes of uneven wallthickness are uneven heating, top bar bending, rolling line is not right, centering roller adjustment improper, centering hole and improper import sleeve selection. 

2 The inner fold causes of the perforation of the inner folding piercing are more, which can be divided into two kinds: the steel inner folding and the operation inner folding. 

(1) Steel internal folding. 

is mainly caused by poor quality, such as continuous casting billet (residual shrinkage, internal cracks, non-metallic inclusions, etc.), casting billet internal serious loose, columnar crystals over developed and difficult to deformation of alloy steel perforation is also easy to produce inner fold. 

(2) operating within the fold. The main reasons are improper adjustment (such as too large or too small, the roller speed is too high, the angle is too small, the ellipse is too large) and the heating temperature of the tube is not equal, the head wear too large or rupture, sticky steel and so on. 

An inner fold is also caused by the insertion of a broken tail at the end of a stick. 

3 The main reasons for the external folding are steel external folding and operation of the folding. 

(1) Steel external folding, such as crack of tube billet, serious scratches of cc billet, Rzi, Scar of ingot, Hippi and bubble of subcutaneous. 

(2) operation of the external fold. 

Tool (Roll, guide or guide plate) stick steel scratches, serious spiral road, roller groove or surfacing improper.