*3.2. Simulation Analysis of the Profiling Mechanism of the Lower Cutterbar*

The changes in the upper and lower cutterbars, as well as the varying *LBA* while the DCH descended, are displayed in Figure 12. At the beginning of the simulation, under the effect of gravity, the height-limiting block and the swing block make contact with each other; no relative sliding occurs between the height-limiting connecting rod and the swing block; and the lower and upper cutterbars descend simultaneously. The simulation time is 0.185 s. In the profiling mechanism, the ground wheel makes contact with the ground, the height of the lower cutterbars no longer shows a large range of change, and the header continues to descend. Meanwhile, due to the supporting effect of the ground surface on the ground wheel, the height-limiting connecting rod begins to move upwards along the swing block, and the height of the lower cutterbars slowly drops, accompanied by a decrease in *LBA*; the simulation ends when the height of the upper cutterbars reaches 400 mm. In this case, the upper and lower cutterbars no longer change positions. The height of the lower cutterbars is 100 mm, and *LBA* is decreased from 328.6 mm to 280.2 mm.

**Figure 12.** Motions of the components with the DCH descending. (**a**) Height change of the upper and lower cutterbars; (**b**) Length change of the *L*BA.

In the simulation of the motion of components with the change in ground heights during harvesting, the changes in upper cutterbars and lower cutterbars, as well as varying *L*BA, are displayed in Figure 13. The height of the upper cutterbars is kept unchanged, while the height of the lower cutterbars, when a hump is encountered on the ground wheel, increases and decreases in the case of a concave ground profile, finally realizing the function of the profiling mechanism. According to Figure 13b, in this process, *LBA* is shown to change within the range of 254.7 mm to 322.1 mm. By combining the change in *LBA* during the descent of the header with the dimensions of the swing block and height-limiting block, the length of the height-limiting connecting rod of the profiling mechanism is found to be 365 mm.

**Figure 13.** Motions of the components during harvesting. (**a**) Height change of the upper and lower cutterbars; (**b**) Length change of the *L*BA.
