印花镀锌彩钢板锌花不均解读
性能特点：印花彩钢板单面尺寸不均匀或上下表面锌片尺寸不一致。
原因：
影响
印花彩钢板均匀性的最根本原因是锌花形核和生长过程中外部环境的不一致性，通常表现为带钢表面应力、粗糙度或温度不均匀。
当带钢表面应力不均匀时，如气刀与带钢不平行，两气刀夹角差过大，板表面喷吹气压高的区域冷却速度快，锌片在长大前已凝固；当钢带表面应力不均匀时，气刀与钢带之间的夹角差过大，
印花彩钢板板面喷吹气体压力高的区域冷却速度快，锌片在长大前已经凝固低压区速度慢，温度高，锌片尺寸大。下沉辊和稳定辊磨损引起的振动和板形不良会导致带钢表面应力不均匀。
在镀铝锌制品生产中，带钢离开
印花彩钢板锌锅后的冷却速度和退火炉内带钢的温度波动，导致锌片在低温区形核迅速，尺寸较小，而在高温区，锌花成核速度慢，尺寸大。
原钢带表面粗糙度越高，形核越多，锌片越小；表面粗糙度越小，形核越少，锌片越大。粗糙度不均匀的主要原因如下：
1） 下沉辊、稳定辊磨损或下沉辊稳定辊转动不灵活引起带钢晃动，造成带钢表面划伤；
2） 当原钢带表面清洁度差或清洗段不干净时，钢板表面的油在退火炉中挥发前碳化，包裹在钢基铁粉表面，使还原过程难以进行，导致过度结晶钢带表面的点；
3） 由于炉辊表面结瘤、带钢在炉内划伤、原板表面氧化皮增加，涂层表面粗糙度不均匀；
4） 原材料的粗糙度参差不齐。
改进计划。
1） 调整气刀与带钢的距离和平行度，气刀角度一般在-4°～+1°之间；
2） 提高锌锅机械系统的稳定性，控制进料形状，避免钢带晃动；
3） 减少带钢表面裂纹；
4） 提高清洗设备的清洗能力；
5） 加强带钢锌锅温度控制，保证板表面温度均匀；
6） 提高原料粗糙度的均匀性。
Performance characteristics: the single side of galvanized steel sheet is uneven in size or the size of zinc flake on the upper and lower surfaces is inconsistent.
Causes:
The most fundamental reason for affecting the uniformity of zinc flake is the inconsistency of the external environment during the process of zinc flower nucleation and growth, which is usually manifested in the uneven stress, roughness
or temperature on the surface of strip steel.
When the stress on the surface of the strip steel is uneven, such as the air knife is not parallel to the strip steel, the angle difference between the two air knives is too large, the cooling speed
of the area with high injection gas pressure on the plate surface is fast, and the zinc flake has solidified before it grows; the cooling speed of the area with low pressure is slow, the temperature is high, and the zinc flake size is large. The vibration
and bad shape of strip caused by wear of sink roll and stabilizer roll will cause uneven stress on the surface of strip steel.
In the production of aluminized zinc products, the cooling rate of the strip after leaving the zinc pot and the temperature
fluctuation of the strip in the annealing furnace lead to the rapid nucleation and small size of the zinc flake in the low temperature region, while the zinc flower nucleation is slow and the size is large in the high temperature area.
The higher
the surface roughness of raw steel strip is, the more nucleation and the smaller the zinc flake; the smaller the surface roughness is, the less nucleation is and the larger the zinc flake is. The main reasons for uneven roughness are as follows:
1) Strip steel shaking caused by wear of sink roll and stabilizing roll or inflexible rotation of stabilizing roll of sink roll will cause Scratch on strip steel surface;
2) When the surface cleanliness of raw steel strip is poor or the cleaning
section is not clean, the oil on the steel plate surface is carbonized before volatilization in the annealing furnace, which is wrapped on the surface of steel-based iron particles, making the reduction process difficult to carry out, resulting in excessive
crystallization points on the surface of steel strip;
3) The surface roughness of the coating will be uneven due to the nodulation on the surface of the furnace roll, the scratch of the strip in the furnace and the increase of the oxide scale on
the surface of the original plate;
4) The roughness of raw materials is uneven.
Improvement plan.
1) Adjust the distance and parallelism between the air knife and the strip steel, and the air knife angle is generally between - 4 ° and
+ 1 °;
2) Improve the stability of the mechanical system of zinc pot, control the shape of the incoming material and avoid the steel strip shaking;
3) Reduce sratch on the surface of strip steel;
4) Improve the cleaning capacity of cleaning
equipment;
5) The temperature control of strip steel zinc pot should be strengthened to ensure the uniformity of plate surface temperature;
6) Improve the uniformity of raw material roughness.
