In the
stainless steel production process, the shape control is mainly to ensure that the horizontal thickness is uniform and the shape is straight. The two concepts of transverse thickness difference and strip flatness are not the same.
The transverse thickness difference refers to the relevant index of the uneven thickness distribution on the cross section of the stainless steel strip; the flatness of the steel strip is an index representing the defects such as wave shape and warpage of the stainless steel strip. The direct cause is the rolling The steel strip is deformed unevenly in the width direction. The two have little influence on each other, but both are affected by the roll shape of the work roll during rolling.
Therefore, the shape control process is to adjust the shape of the loaded roll gap under the condition that the incoming hot-rolled stainless steel plate is in good shape, so that it is consistent with the cross-sectional shape of the incoming steel strip, thereby reducing the lateral uneven deformation and making the rolling The plate shape is more straight. Adjusting the shape of the loaded roll gap is relatively easy for many types of twenty-high mills. Because the 20-high rolling mill has a variety of flatness adjustment methods, there are usually radial roll shape adjustment mechanisms and axial roll shape adjustment mechanisms; the split type rolling mill also has the function of roll tilt adjustment; some directly pressed 20 rolls The rolling mill will also be equipped with a hydraulic roll bending mechanism, etc. For a four-high rolling mill, the most basic method for shape control is to determine the appropriate roll crown, that is, considering the pressure distribution characteristics in the width direction of the stainless steel strip, grinding the roll into the middle part Slightly convex shape.
In addition, the quality of stainless steel plate shape is also affected by other operating factors, such as the appropriateness of tension and rolling pressure. Usually the quality of the plate shape is reflected by the tension of each part along the width direction of the stainless steel strip during the rolling process, and in this regard, the actual operator needs to judge and make corresponding adjustments based on experience.
In addition, the thickness of qualified cold-rolled stainless steel strips should be kept uniform and the deviation is low, which is also an important indicator for comparing the quality of stainless steel plates. To control the thickness of the stainless steel strip, to a large extent, it is necessary to do a good job in the rolling precision control of cold rolling. It is necessary to reduce and eliminate the uneven thickness as much as possible, and to reduce the range of thickness deviation as much as possible.
There are two reasons for the uneven thickness of stainless steel strips. One is that the cold-rolled raw materials are not up to standard, such as the uneven thickness of hot-rolled stainless steel coils or the poor annealing of the billets, which makes the deformation resistance of the stainless steel strips in the length direction uneven; One is caused by the cold rolling process, such as changes in tension and speed, roll eccentricity, and changes in the thickness of the oil film of the roll bearings. If it is the former reason, it is necessary to improve the previous process and try to eliminate the influence in the cold rolling process. For the second reason, some experience is required to improve process operations.
