## 5 Results and Discussion
### MSCL Control Method  
The above research is based on the analysis of the \"displacement-time control of uniform speed feeding\". Through the analysis of the deformation degree of the flanging lip and the process quality, it is shown that the feeding displacement and the staking load should be controlled. In practice, the \"displacement-time control of uniform speed feeding\" or \"force-time control of constant force feeding\" is often adopted [25; 26; 27; 28]. However, the above analysis shows that when the \"displacement-time control of uniform speed feeding\" is adopted, it causes bearing \"locking\" and material damage at a later stage of the roller staking process [10; 29]. For the \"force-time control of constant force feeding\", the contact position between the roller and the flanging lip is likely to be pressed out of a \"pit\" in the initial stage of the process, which will damage the material of the flanging lip [30; 31]. Therefore, a \"Multi-Stage Composite Loading (MSCL)\" control method is proposed in this study to realize the effective control of the staking load, feeding displacement, and deformation degree of the flanging lip. The schematic diagram of the speed-time and force-time curves of the three methods are shown in Figure 9. The solid line in the figure represents \"active monitoring\" and the dotted line represents \"passive control\". Figure 9a shows the control method of the \"displacement-time control of uniform speed feeding\", which is commonly used at present. During the roller staking process, the rotate speed of the roller tool and the feeding speed are constant, and the staking load is monitored. In the latter period of the roller staking process, the staking load increases sharply, and it is easy for staking to not be in place or be excessively squeezed, and even for there to be material damage of the flanging lip. Figure 9b shows the control method of the \"force-time control of constant force feeding\". During the roller staking process, the rotate speed of the roller tool and the staking load are constant, and the feeding displacement is monitored. In the early period of the roller staking process, the contact area between the roller and the flanging lip is small, which makes the feeding speed at the beginning of the roller staking too large. It is easy to press out a \"pit\" or defects such as large deformation of the flanging lip, resulting in material damage at the flanging lip tip. At the same time, the frictional contact between the roller tool and the flanging lip may be unstable, resulting in poor surface quality of the flanging lip. Based on the analysis of the above two process-loading control methods, a new process-loading control method is proposed in this paper to reduce staking quality defects. Figure 9c shows the MSCL control method, i.e., the rotate speed of the roller tool is constant  
Figure 9: Schematic diagram of the speed–time and force–time curves of the three process-loading control methods: (**a**) Displacement–time control; (**b**) Force–time control; (**c**) MSCL control. during the roller staking process, and multi-stage control is adopted. The control process is as follows: in the time period of 0-\(t_{1}\), displacement-time control is adopted, the feeding speed (\(v_{1}\)) remains constant, and the staking load is monitored. When the staking load reaches \(F_{1}\), the force-time control for the time period of \(t_{1}\)-\(t_{2}\) is entered. The staking load \(F_{1}\) remains constant, the feeding displacement is monitored to (0.5-0.6) \(k\), and rolling continues for a while to polish the surface of the flanging lip, and then the control process is completed.