*3.3. Regression Model Optimization*

In order to optimize the working parameters of the reciprocating cutting system, the maximum cutting stress of the upper cutter and the bottom cutter were set as the optimal object, and the optimization model was established as follows:

$$ \begin{cases} \begin{array}{l} f = \min Y\_1 \\ f = \min Y\_2 \end{array} \\ \begin{cases} 20^\circ \le X\_1 \le 30^\circ \\ 35^\circ \le X\_2 \le 45^\circ \\ 300 \text{ mm/s} \le X\_3 \le 500 \text{ mm/s} \end{cases} \end{cases} \tag{6} $$

The model was optimized by using Design-Expert 10.0.7 software's data optimization module, Optimization and the optimal cutting parameter combination for the reciprocating cutting system of greens was obtained: sliding–cutting angle was 29◦, oblique angle was 38◦, and average cutting speed was 500 mm/s. The maximum equivalent stress in cutting of the upper cutter and the bottom cutter is the minimum value, and their predicted values are 0.95 and 0.77 Mpa, respectively.

#### *3.4. Analysis of Cutting Performance Test Results*

The root moisture calculated by Equation (3) was 88.7% ± 2.1%, and the difference in moisture content between samples was small, indicating that the root moisture content had little effect on the test results. In order to verify the accuracy of the numerical simulation results and the actual cutting effect, the cutting performance test was carried out according to the equipment and methods described in Section 2.4.

The resistance strain gauge collected normal stress of both blades and obtained four sets of data. Figure 13 shows the maximum normal cutting stress results when the sliding–cutting angle is 29◦, the oblique angle is 38◦, and the average cutting speed is 300, 400, and 500 mm/s. In three sets of physical tests, the maximum cutting stress in the *X* direction of each group is less than the maximum cutting stress in the Y direction, which is consistent with the numerical simulation results. As the average cutting speed decreases, the maximum cutting stress shows an increasing trend, and the test index is the minimum when the average cutting speed is 500 mm/s. The physical test verifies the reliability of the test platform. The parameters of the Chinese little greens cutting device were optimized.

**Figure 13.** Maximum normal cutting stress at different average cutting speeds used in the physical tests.
