# Research on Springback Compensation Method of Roll Forming Based on Improved Fuzzy PID Control
## 4 Experimental Verification  
The equipment utilized in the experiment is a prototype of a horizontal upward-adjusting three-roll plate bending machine (Wuhan, China). In order to verify the universality of the kinematic model for circular rolling springback compensation, the horizontal upward-adjusting three-roll plate bending machine was used to carry out roll bending experiments on aluminum alloy plates, Q235 steel plates, and 20 steel plates. The desired radius was set at 40 mm. The results are presented in Table 6, and the forming effects are shown in Figures 11-13. When the springback compensation strategy was not applied, the errors between the circular roll forming radii and the desired radius for the aluminum alloy plate, Q235 steel plate, and 20 steel plate were 5.40%, 5.32%, and 5.52%, respectively. After the implementation of the springback compensation strategy, the errors between the circular roll forming radii and the desired radius for the aluminum alloy plate, Q235 steel plate, and 20 steel plate were reduced to 1.60%, 1.55%, and 1.72%, respectively. This demonstrates that the kinematic model for circular rolling springback compensation can effectively predict the circular roll forming radius.  
Figure 11a shows the effect of the circular roll forming of the aluminum alloy sheet metal. In the figure, for the cylinder on the left during the rolling process, the springback compensation strategy was not applied, while for the cylinder on the right during the rolling process, the springback compensation strategy was applied. In Figure 11b,c, \"Not Applied\" indicates that the springback compensation strategy was not applied, and \"Application\" indicates that the springback compensation strategy was applied.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Expected Radius** & \
\begin{tabular}{c} **Not Applying the Springback** \\ **Compensation Strategy to Roll Radius** \\ \end{tabular} &
\begin{tabular}{c} **Applying the Springback** \\ **Compensation Strategy to Roll Radius** \\ \end{tabular} \\ \hline Aluminum alloy & 40 mm & 42.16 mm & 40.64 mm \\ Q235 Steel & 40 mm & 42.13 mm & 40.62 mm \\
20 Steel & 40 mm & 42.21 mm & 40.69 mm \\ \hline \hline \end{tabular}
\end{table}
Table 6: Roll forming results.  
Figure 11: Circular roll forming of aluminum alloy sheet metals. (**a**) Aluminum alloy sheet roll forming effect. (**b**) The relationship between the distance from the sensor to the midline and time during the circular roll forming of aluminum alloy sheet metals. (**c**) The relationship between the horizontal displacement of the slide block and time during the circular roll forming of aluminum alloy sheet metals.  
Figure 12: Circular roll forming of Q235 sheet metal. (**a**) The forming effect of circular rolling for Q235 sheet metal. (**b**) The relationship between the distance from the sensor to the midline and time during the circular roll forming of Q235 sheet metal. (**c**) The relationship between the distance from the sensor to the midline and time during the circular roll forming of Q235 sheet metal.  
Figure 13: Circular roll forming of 20 steel sheet metal. (**a**) The forming effect of circular rolling for 20 steel sheet metal. (**b**) The relationship between the distance from the sensor to the midline and time during the circular roll forming of 20 steel sheet metal. (**c**) The relationship between the horizontal displacement of the slide block and time during the circular roll forming of 20 steel sheet metal.