## 2 Materials and Methods
### Key Component Parameter Design and Analysis  
#### 2.2.1 Primary Crushing Roll Design  
To ensure a qualified rate of HCME crushing and improve the crushing efficiency, it is necessary to clarify the structural parameters of the first-stage differential crushing roller. The same blade spacer is set between the two blades to allow the chopped corn to have better fluidity. To improve the crushing effect and crushing rate, the two pairs of roller blades are arranged in a staggered manner. The length of the ear fragmentation zone directly influences the final fragmentation effect, because maize ears generally fall with their axes aligned parallel to the axes of the crushing rollers. The corn ear crushing zone is defined as the area where the two primary crushing rolls overlap. The principle of the fragmentation process is illustrated in Figure 2. To ensure that the maize ears undergoing primary fragmentation are successfully transferred to the secondary roller crushing apparatus, the spacing (b) of the primary tooth-shaped rollers should be controlled at 60 mm. Figure 1: Three-dimensional diagram of HCME crushing device. Components: 1, feeding hopper; 2, primary crushing roller; 3, receiving hopper; 4, discharge hopper; 5, secondary crushing roller; 6, conveyor belt; 7, frame; 8, transmission components; 9, electrical control box; 10, motor. Figure 2: Diagram of the principle of corn ear shattering. The required productivity is 20 t/h, and the corn ear capacity is approximately equal to 500 g/L [21]; 20 t of high-moisture corn ear volume V ears must reach about 28 m\({}^{3}\) to achieve this productivity; the calculation formula for the first level of the toothed crushing or roller crushing area S\({}_{0}\) is as follows:  
\[S_{0}=nbl, \tag{1}\]  
where S\({}_{0}\) is the effective crushing area, m\({}^{2}\); b is the number of blades; and l is the effective crushing length, m.  
Bringing in the numerical value to derive the effective crushing area S\({}_{0}\) = 0.03 m\({}^{2}\) of the primary crushing roller leads to the maximum value of the primary crushing roller D\({}_{\text{max}}\), as follows:  
\[D_{\text{max}}=\frac{b+dc\infty\alpha_{1}}{2(1-\cos\alpha_{1}{}^{2})}, \tag{2}\]  
where D\({}_{\text{max}}\) is the maximum diameter of the primary crushing roller, m; \(\alpha_{1}\) is the corn ear contact angle with the knife teeth; d is the corn ear diameter, m; and b is the effective crushing width, m.  
To meet the strength requirements of the device, the blade material is selected as 65 Mn steel and the corn ear friction angle is 35.7\({}^{\circ}\), so \(\alpha\leq\) 35.7\({}^{\circ}\); to meet the productivity requirements, the above data will be analyzed to find D\({}_{\text{max}}\)\(\leq\) 420 mm. The primary crushing roller diameter D\({}_{\text{min}}\) value of the formula for calculating the diameter of the primary crushing roller D\({}_{\text{min}}\) is shown in Equations (3)-(5), to meet the crushing requirements of 20 t/h, based on the effective crushing area of the primary crushing mechanism obtained above, through the calculation of the falling speed of the crushed material (with the size of the crushing roller linear speed), and then we can obtain the minimum diameter of the primary crushing roller D\({}_{\text{min}}\). \[Q=S_{0}\times v \tag{3}\]  
\[v=\omega\times r=\pi\times D\times\frac{n}{60} \tag{4}\]  
\[D_{\text{min}}=60Q/S_{0}n\pi, \tag{5}\]  
where Q is the volumetric flow rate; v is the linear velocity, m/s; \(\omega\) is the angular velocity, rad/s; r is the corn ear radius, m; and D\({}_{\text{min}}\) is the minimum diameter of the primary crushing roller, m.  
We finally obtained a crushing blade diameter D \(\geq\) 170 mm. Summing up the above, it can be concluded that the diameter of the first crushing blade D is 170 to 420 mm.