## 3 Thickness Control and Static Comprehensive Analysis of Rolling Process  
### Mechanism Analysis of Aluminum Alloy Strip Rolling Process  
Strip production is a complex industrial process with multi-process cooperation. In this process, melting, casting, rolling and other processes are concentrated in one production line as shown in Figure 2. The strip rolling stage is composed of multiple stand units, and the rolling at this stage requires the coordination of multiple stands. The process unit of each working procedure in the production process is complex. The strip quality is inherited among the working procedures. In this paper, the rolling process is taken as the research object, and the quality monitoring model is established to achieve the goal of strip thickness monitoring. In the rolling stage, the metals undergo elastic-plastic deformation under the action of the force between the rolls. As a result of elastic deformation, the actual reduction of the roll is reduced, and the exit thickness of the rolled piece is greater than the value of the no-load roll gap as shown in Figure 3. Therefore, strip thickness and elastic flattening constitute the basis of strip thickness control. Figure 2: Production process of aluminum alloy plate and strip. In order to optimize the mechanism of the strip thickness quality monitoring data model, this part analyzes the strip thickness control mechanism. Based on the change principle of the elastic-plastic curve, the related control factors of strip thickness are analyzed. Under the actual rolling conditions, the roll gap is closely related to the thickness. In order to describe the relationship between the total elastic deformation of the rolling mill and rolling pressure, the spring equation of the rolling mill is established [34]. According to the elastic curve, the thickness of the rolled exit strip is shown in the following formula. \[h=s_{0}+\Delta s=s_{0}+\frac{P}{K} \tag{24}\]  
\[K=P/(h-s_{0}) \tag{25}\]  
where \(s_{0}\) is the empty roll gap, \(\Delta s\) is the deformation of stand under rolling force, \(P\) is the rolling pressure, and \(K\) is the stiffness coefficient of the rolling mill. For the longitudinal thickness of the strip, the longitudinal stiffness of the rolling mill is mainly considered. In addition to the influence of the state of the incoming rolled piece, the longitudinal thickness of the strip will change as long as the rolling pressure fluctuation is involved in the rolling process. In order to eliminate the thickness deviation caused by disturbance factors, the intersection point of two characteristic curves is returned to the preset point. This section briefly introduces the corresponding plate thickness control means [35]. When the thickness of incoming material fluctuates greatly, the original rolling conditions cannot meet the requirement of rolling out thickness. At this time, changing the size of the reduction offsets the rolling factor or the thickness deviation caused by rolling pressure fluctuation due to the interference of the rolling mill system. As shown in Figure 4 the expected rolling thickness is \(h_{0}\). Other conditions of the rolled piece remain unchanged; thus the slope of the plastic curve \(B\) remains the same. However, the increase in blank thickness makes the curve shift to \(B^{\prime}\) to the right, intersects with the original rolling mill elastic curve \(A\) to \(h_{1}\), which leads to the corresponding thickness deviation of \((h_{1}-h_{0})\). At this time, the thickness control system of the rolling mill reacts by increasing the reduction and reducing the roll gap, and thus the elastic curve of the rolling  
Figure 3: Schematic diagram of elastic deformation of rolling gap. mill shifts to the position \(A^{\prime}\). The abscissa of the intersection point comes to \(h_{0}\) again so as to eliminate the thickness deviation. On the other hand, when the thickness of the incoming material is normal, there are some problems such as uneven temperature and fluctuation of hardness or microstructure.