Common Quality Defects in Cold Rolled Products and Their Corrective Measures (Part 2)

Shape Defects

1. Beveling

   • Process Stages: Pickling, rolling, finishing

   • Description: Angled edges on steel coils or strips after edge trimming

2. Sickle Bending

   • Process Stages: Cold rolling, smoothing, leveling

   • Causes: Unbalanced rolling force across strip width, delayed response in force adjustment, uneven roll gap settings, or inconsistent material density and hardness

3. Wave Patterns (including unilateral wave, bilateral wave, center wave, oblique wave)

   • Process Stages: Cold rolling, smoothing, leveling

   • Causes: Non-uniform material density/hardness, slow response in rolling force/bending force adjustments, excessive tension fluctuations, significant diameter difference between top and bottom rolls

4. Buckling

   • Process Stages: Hot rolling, cold rolling, smoothing, leveling

   • Causes: Uneven density or hardness through material thickness, resulting in differential plasticity between top and bottom surfaces

Coil Configuration Defects

1. Telescoping

   • Process Stage: Coiling operation

2. Bulging

   • Process Stage: Coiling operation

   • Cause: Excessive edge thinness leading to coil expansion during continuous winding

3. Drum Ears

   • Process Stage: Coiling operation

   • Cause: For galvanized coils, overly thick edges can cause end protrusions during coiling

Dimensional Defects

1. Thickness Deviation

   • Process Stage: Rolling process

   • Cause: Inaccurate rolling control parameters

2. Width Shortfall

   • Process Stage: Trimming operation

   • Causes: Improper trimming settings or pre-existing edge defects in raw material

3. Length Deviation

   • Process Stage: Slitting operation

   • Cause: Control system inaccuracy