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Characteristics and influence of unit pressure distribution of packaging steel strip
by：Hongmei
2021-03-15
Characteristics and influence of unit pressure distribution of packaging steel strip
The measured unit pressure curve under the condition of cold-rolled thin test piece. It can be seen that the distribution of unit pressure p along the connecting arc is extremely uneven, with obvious peaks and very close to the outlet section. If the connection curve of the unit pressure value of the inlet and outlet sections is approximated as the hardening curve of the pass metal, it can be The area under the unit pressure distribution curve is divided into two parts: the lower part is called the base part, which reflects the influence of the material properties itself, and the upper part is called the friction peak, which reflects the influence of external factors such as friction conditions. Obviously, in addition to the obvious influence of the work hardening of the material on the characteristics of the unit pressure distribution curve, the influence of the friction condition is more serious.
Because the unit pressure distribution curve has the above characteristics, the cold rolling process has a series of characteristics and has many adverse effects on the cold rolling process. First, compared with other rolling conditions, the average unit pressure p and rolling force p in the cold rolling process are very large, and can be doubled or even increased several times. Secondly, a large amount of friction energy will be converted into frictional heat, which makes cold rolling. The rolling process produces severe thermal effects, and the overflow of the rolls and rolled pieces can be increased to above 100-120℃, so they must be effectively cooled, otherwise, it will affect the service life, lubrication effect, and energy consumption of the rolls. The surface quality of the product has a serious impact. After pumping, if the section where the maximum unit pressure is located is approximately regarded as the neutral surface, the neutral angle γ is very small, resulting in a very small forward slip Sh, generally only (1-5)%. The actual measurement shows that in the 350mm three-frame cold On the finished product stand of the continuous rolling mill, in some cases, negative forward slip may even occur. Theoretical analysis shows that when the negative front slip exceeds a certain critical value, it will cause slipping, making the rolling process unstable, and scratching the surface of the strip and rolls.
The measured unit pressure curve under the condition of cold-rolled thin test piece. It can be seen that the distribution of unit pressure p along the connecting arc is extremely uneven, with obvious peaks and very close to the outlet section. If the connection curve of the unit pressure value of the inlet and outlet sections is approximated as the hardening curve of the pass metal, it can be The area under the unit pressure distribution curve is divided into two parts: the lower part is called the base part, which reflects the influence of the material properties itself, and the upper part is called the friction peak, which reflects the influence of external factors such as friction conditions. Obviously, in addition to the obvious influence of the work hardening of the material on the characteristics of the unit pressure distribution curve, the influence of the friction condition is more serious.
Because the unit pressure distribution curve has the above characteristics, the cold rolling process has a series of characteristics and has many adverse effects on the cold rolling process. First, compared with other rolling conditions, the average unit pressure p and rolling force p in the cold rolling process are very large, and can be doubled or even increased several times. Secondly, a large amount of friction energy will be converted into frictional heat, which makes cold rolling. The rolling process produces severe thermal effects, and the overflow of the rolls and rolled pieces can be increased to above 100-120℃, so they must be effectively cooled, otherwise, it will affect the service life, lubrication effect, and energy consumption of the rolls. The surface quality of the product has a serious impact. After pumping, if the section where the maximum unit pressure is located is approximately regarded as the neutral surface, the neutral angle γ is very small, resulting in a very small forward slip Sh, generally only (1-5)%. The actual measurement shows that in the 350mm three-frame cold On the finished product stand of the continuous rolling mill, in some cases, negative forward slip may even occur. Theoretical analysis shows that when the negative front slip exceeds a certain critical value, it will cause slipping, making the rolling process unstable, and scratching the surface of the strip and rolls.
