Design, Testing, and Optimization of a Filling-Type Silage Crushing, Shredding, and Baling Integrated Machine

Abstract

To address the limitations of large silage machines in hilly and small-scale farming regions and the inefficiencies of existing small-scale crushing and baling machines, in this study, we developed an integrated silage crushing, shredding, and baling machine. Using discrete element software (EDEM 2022.3), the baling process of shredded straw was simulated, achieving a baled grass density of 140.067 kg/m³, meeting practical requirements. A three-factor, three-level experiment was conducted to evaluate the effects of the hammer blade quantity, blade length, and hammer angle on machine productivity and straw shredding rate. Performance data were analyzed using Design-Expert 10.0.7 software to develop regression models and assess the significance of each factor. The results indicated that productivity was most influenced by hammer blade quantity, followed by blade length and hammer angle, while the shredding rate was primarily affected by blade length, then hammer blade quantity, and hammer angle. The optimal configuration was identified as 32 hammer blades, a blade length of 99 mm, and a hammer angle of 14°. Validation experiments demonstrated a productivity of 2815.29 kg/h, a straw shredding rate of 94.28%, and a baled grass density of 124.52 kg/m³, closely aligning with the predicted values and confirming the reliability of the optimization.

1. Introduction

China has extensive and abundant crop resources, with rice, wheat, and corn being the most widely distributed and cultivated crops, producing over 800 million tons of crop straw annually [1]. However, only about 33% of this straw is effectively utilized, such as for silage feed, while the rest is either burned or discarded in fields, leading to environmental pollution and resource waste [2].

As China’s animal husbandry sector grows rapidly, converting straw into feed offers an effective solution for the shortage of raw materials for livestock production. The crushing and shredding of straw are essential stages in the integrated utilization of these resources. This process transforms silage straw feed into soft, fluffy, filament-like fragments, which expose nutrients and increase the contact area with livestock digestive systems. The resulting feed is rich in nutrition and highly digestible and has a higher storage capability, making it a crucial dietary component for ruminants such as cattle and sheep [3,4].

Large farms and ranches are prevalent abroad, where large-scale silage processing machines are well developed and come in a wide variety of models. Self-propelled forage harvesters typically operate in conjunction with transport vehicles. Representative models include the 9000 series from John Deere (Moline, IL, USA) [5], the FR series from New Holland (New Holland, PA, USA) [6], the JAGUAR series from CLAAS (Harsewinkel, Germany), the BiG X series from KRONE (Duisburg, Germany) [7], and the RSM series from Rostselmash (Rostov-on-don, Russia) [8].

In China, recent research has focused on small-scale silage crushing, shredding, and baling machinery. Numerous new models have been introduced, such as the 9RS-3 straw shredder [9], the 9RC-200 household double-sided straw slicer [10], the 9FH-40 corn straw shredder [11], and the 9LRC-60 vertical straw rubbing machine [12]. The high moisture content of silage straw, which increases its toughness, makes existing baling machines exhibit low crushing efficiency and poor shredding quality [13]. Additionally, known small shredders are unable to perform integrated baling and filling operations [14,15,16,17,18].

To address challenges such as the unsuitability of large silage processing machines for small-scale farming, low crushing efficiency, poor shredding quality, labor-intensive manual filling, and inadequate sealing performance of small silage processing machines [19], this study focused on whole green maize as the processing target. A filling-type silage crushing, shredding, and baling integrated machine was designed. By coordinating the processes of crushing, shredding, and baling, along with the manual bagging and sealed storage of silage bags, the integrated filling of silage feed was achieved. This design improves production efficiency and provides technical support for advancing silage processing technologies in hilly and small-scale farming areas [20].

2. Materials and Methods

2.1. Overall Structure

Based on the requirements for silage feed processing and storage, the overall structure of the machine is shown in Figure 1. The machine primarily comprises a chain conveyor mechanism, a roller feeding mechanism, a crushing and shredding mechanism, a baling and bagging mechanism, a frame, a crushing motor, and a baling motor. The coordinated operation of these components ensures the functionality of the entire system.

2.2. Working Principle

During operation, whole green maize is manually transported to the chain conveyor mechanism and fed into the roller feeding mechanism. The flattening roller moves up and down based on the amount of straw being fed, automatically adjusting the feed opening to ensure continuous and uniform feeding. The wire-stripping roller and flattening roller clamp the silage straw, ensuring consistent lengths of material as it enters the crushing and shredding mechanism. At this stage, the material undergoes breaking, wire-stripping, and flattening.

The silage feed is then transported into the crushing and shredding chamber, where high-speed rotating serrated curved hammer blades, along with inner wall nails and jaw tooth plates, chop, collide with, tear, compress, and repeatedly rub the material, shredding it into a filamentous form. Filamentous material of the appropriate length is propelled into the baling and bagging mechanism via airflow and the centrifugal force generated by the high-speed rotor.

Within the baling mechanism, the material is further conveyed by a helical blade. The combined effects of the blade’s thrust, external forces at the cylinder’s end, friction from the inner wall, and counterforces from the cylinder wall compact the material, compressing it into cylindrical bales. The bales, with a diameter of 300 mm and a width of 500 mm, are discharged from the outlet. Finally, the bales are manually bagged and sealed in silage bags for storage, completing the integrated filling process.

2.3. Transmission System

The machine employs two independent power transmission systems, each driven by its own electric motor. The shredding motor drives the chain conveyor mechanism, roller feeding mechanism, and the crushing and shredding mechanism, while the baling motor powers the baling and bagging mechanism. The entire transmission consists of pulleys, gears, sprockets, shafts, and fasteners. The transmission modes include belt, gear, and chain transmissions, as shown in Figure 2. The shredding motor setup utilized a three-phase asynchronous motor (Model: YE132S-4, Manufacturer: Lanzhou Tezhong Electromechanical Equipment Co., Ltd., Lanzhou, China), which provided a rated power of 5.5 kW and a rotational speed of 1440 rpm. The baling motor is a three-phase asynchronous motor (Model: YE3-132M-6, Manufacturer: Fangli Holdings Co., Ltd., Shenzhen, China), which provided a rated power of 5.5 kW and a rotational speed of 964 rpm.

2.4. Main Mechanism Designs and Force Analyses

2.4.1. Straw Conveying Mechanism

The chain conveyor mechanism consists of a concave grate plate, a driving sprocket, a driving shaft, conveyor chains, positioning bolts, a driven shaft, and protective plates (as shown in Figure 3). The mechanism is based on two perforated side-plate conveyor chains, with the concave grate plate riveted onto the chains. Positioning bolts are used to limit the displacement of the driven shaft and achieve tensioning, ensuring uniform and orderly straw conveyance. To ensure safety in terms of conveying distance and feed volume, the transmission components employ a specially designed double-side-plate perforated 12A-1 roller chain. The conveying distance is designed to be 1000 mm, with a concave grate plate length of 260 mm and a spacing of 200 mm between the two conveyor chains [21].

Considering the designed production capacity and feed inlet of the machine, along with the physical characteristics and slip rate of the silage, the conveyor chain speed is set at 0.6 m/s. The main shaft speed of the conveyor chain is then calculated using the following formula [22]:

$$n_L={\displaystyle \frac{60\times 1000v_L}{\pi d_L}}$$

(1)

where $n_L$ is the rotational speed of the conveyor chain’s main shaft in rpm; v_L represents the conveyor chain speed in m/s; and d_L represents the revolving diameter of the conveyor chain in mm. The meanings of the symbols used in this article are provided in the Appendix A, and the same applies hereafter.

According to the assembly relationship, the rotation diameter of the conveyor chain should be larger than the pitch circle diameter of the driving sprocket, with a measured value of d_L = 140 mm. Substituting into the calculation, the main shaft rotational speed of the conveyor chain is 82 rpm.

2.4.2. Straw Roller Feeding Mechanism

The straw feeding process is a critical component of the straw crushing and kneading machine. Its stability and continuity directly affect the efficiency of subsequent operations, including crushing, kneading quality, and baling density. The roller feeding mechanism primarily consists of a guard plate, a flattening roller, a spring, a scribing roller, a pulley, the main shaft of the conveying mechanism, a driving gear, and a driven gear (see Figure 4). During operation, the flattening and scribing rollers rotate in opposite directions at different speeds. The linear speed of the flattening roller is 1.2 times that of the scribing roller, enabling the effective grabbing, flattening, and scribing of straw.

The flattening roller features a floating spring design, allowing it to automatically adjust the feeding port opening based on the amount of straw fed. This ensures continuous and uniform feeding, precise chopping lengths, and reduced feed blockages.

The roller feeding mechanism measures 300 mm in length, 350 mm in width, and 360 mm in height, with a feeding port measuring 260 mm wide and 140 mm high. Both the flattening and scribing rollers are 280 mm long, with diameters of 120 mm. The scribing roller rotates at 120 r/min, while the flattening roller rotates at 143 r/min.

The flattening roller is a smooth cylindrical roller modified to have a 5 mm diameter, with 280 mm long round steel rods evenly distributed along its tangential direction, creating a deep-groove roller with excellent gripping and flattening capabilities. Similarly, the scribing roller is a smooth cylindrical roller modified with 5 mm high and 5 mm wide saw teeth evenly distributed circumferentially, providing excellent scribing ability [23].

To ensure the smooth feeding of straw, the frictional force generated by the rotation of the flattening roller and the scribing roller on the corn straw must exceed the horizontal component of the normal force [24,25]. Both rollers are made of the same material, and the friction coefficient between the straw and the rollers is identical. Figure 5 illustrates the force and motion analysis of the feeding process, where the friction forces and normal forces are calculated with the following formulae:

$$\begin{array}{c}{F}_{f1}\mathit{cos}\alpha +F_{f2}-F_{N1}\mathit{sin}\alpha \ge 0\\ F_{N2}=F_{N1}\mathit{cos}\alpha +F_{f1}+mg\\ {F_{f1}={\mu }_{1}F}_{N1}\\ {F_{f2}={\mu }_{1}F}_{N2}\\ {\mu }_1=\mathit{tan}\beta \end{array}$$

(2)

In Equation (2), μ₁ represents the friction coefficient between the straw and the flattening roller and scoring roller; α represents the angle between the normal force and the vertical direction (degree); β represents the angle of friction for straw (degree); F_N1 represents the normal force exerted by the flattening roller on the straw (N); F_N2 represents the support force exerted by the scoring roller on the straw (N); F_f1 represents the friction force exerted by the flattening roller on the straw (N); F_f2 represents the friction force exerted by the scoring roller on the straw (N); m represents the mass of the straw (kg); and g represents gravitational acceleration (m/s²).

According to Equation (2), when 2tanβ ≥ tanα, the friction angle β of the straw generally ranges from 17° to 27°, the angle α ranges from 32° to 46°, ensuring that the flattening roller can smoothly complete the feeding process [26].

The radii of the flattening roller and scoring roller satisfy the following equations:

$$\begin{array}{c}L=2R_1+h=R_1\left(1+\mathit{cos}\alpha \right)+H\\ R_1\ge {\displaystyle \frac{H-h}{1-\mathit{cos}\alpha }}\end{array}$$

(3)

where R₁ represents the radius of the flattening roller and scoring roller (mm); H represents the thickness of the fed straw flow (mm); h represents the gap between the flattening roller and the scoring roller (mm); and L represents the center distance between the two rollers (mm).

2.4.3. Straw Crushing and Kneading Mechanism

The crushing and kneading mechanism is a key component of silage processing machinery, as the straw processing primarily occurs during this stage, directly affecting the processing quality [27,28]. This mechanism mainly consists of the upper crushing chamber, nail teeth, rotor, curved hammer blades, jaw plate, and lower crushing chamber (as shown in Figure 6). When straw enters the crushing chamber, it is acted upon by high-speed rotating curved hammer blades. Under the combined action of these blades, the jaw plate, and the nail teeth, the straw is repeatedly chopped, torn, compressed, and kneaded until it is crushed into fine material and ejected from the chamber [29].

The machine is designed with nail teeth and a jaw plate installed in the upper and lower kneading chambers, respectively. This arrangement alters the motion path of the straw within the kneading chamber, increasing its fluctuations and the number of impacts, thereby enhancing the fiberization effect.

The machine is equipped with serrated curved hammer blades made of 65Mn steel. These blades cover more crushing and kneading space during operation, increasing the contact area between the straw and the blades, which improves the kneading quality and striking density [30]. The hammer blades are arranged in a symmetrical, staggered pattern, with a total of 32 blades. Each blade has a thickness of 4 mm and a width of 50 mm.

The rotor of the machine has a diameter of 230 mm and a width of 290 mm, with a maximum rotational diameter of 470 mm. The nail teeth have a maximum height of 24 mm, while the jaw plate has a maximum height of 23 mm.

Figure 7 illustrates the force and motion analysis of the straw crushing and kneading process, based on the hammering and kneading forces observed during straw fiberization. At the moment of straw kneading and crushing, the following conditions are satisfied [31,32]:

$$\left\{\begin{array}{c}\sum F_x=F_{f3}+mg\mathit{sin}\gamma -F_{f4}=0\\ \sum F_y=F_1+F_{N3}+mg\mathit{cos}\gamma -F_{N4}=0\end{array}\right.$$

(4)

$$F_1=m{\omega }_5^2{R}_2$$

(5)

$$F_{f3}={\mu }_2{F}_{N3}$$

(6)

$$F_{f4}={\mu }_3{F}_{N4}$$

(7)

where ω₅ is the angular velocity of the hammer blade (rad/s); γ is the angle between the line connecting the straw section and the rotor spindle axis and the vertical direction (degree); F₁ represents the centrifugal force of the straw segment (N); F_N3 represents the support force of the hammer blade on the straw segment (N); F_N4 represents the support force of the lower kneading chamber on the straw segment (N); F_f3 represents the frictional force of the hammer blade on the straw segment (N); F_f4 represents the frictional force of the lower kneading chamber on the straw segment (N); R₂ represents the rotational radius of the straw segment (mm); μ₂ represents the friction coefficient between the straw segment and the hammer blade; and μ₃ represents the friction coefficient between the straw segment and the lower kneading chamber.

2.4.4. Straw Baling and Bagging Mechanism

The baling and bagging mechanism is based on a screw conveyor, designed with a compression chamber without spiral blades and a circular baling cylinder for manual bagging [33,34]. The mechanism mainly includes a screw shaft, spiral blades, pulleys, a baling cylinder, and a compression chamber (as shown in Figure 8). During operation, shredded straw material is fed into the screw conveyor, where the baling motor drives the spiral blades to rotate, moving the material slowly toward the outlet. As material accumulates between the blades, it starts to pile up, and when the material inside the wall reaches a certain weight, the friction force of the inner wall increases, causing the compression density to gradually increase from the outlet to the screw’s end. Simultaneously, as the screw shaft rotates, the phase angle of the spiral blades changes, causing the blades to grip the material and move it past the feed inlet into the baling cylinder. The material is compressed and transported by the pressure exerted by the blades, the main shaft, and the inner wall. As the spiral rotates, the material is conveyed into the compression chamber at the end of the spiral blades. In the compression chamber, the material accumulates and takes shape. When the accumulation reaches a certain quantity, it is subjected to the combined action of external force, thrust from the end of the spiral, and friction from the cylinder’s inner wall. The material is compressed into cylindrical bales [35], extruded from the molding outlet, and manually bagged, sealed, and packed into silage bags, completing the integrated bagging process for silage feed.

The force analysis of the infinitesimal volume of shredded straw material is shown in Figure 9, and it satisfies the following relationship [36]:

$$F_2=Pldh$$

(8)

$$F_3=\left(P+{\displaystyle \frac{\partial P}{\partial z}}dz\right)ldh$$

(9)

$$F_{f5}=f_1\left(Pldz+\rho dzldh{a}_n\right)$$

(10)

$$F_{f6}=f_{3}Pldz$$

(11)

$$F_{N5}=Pdhdz+F_4$$

(12)

$$F_{f1}=f_2\left(Pdhdz+F_4\right)$$

(13)

$$F_{N6}=Pdhdz$$

(14)

$$F_{f8}=f_{2}Pdhdz$$

(15)

$$F_{f9}=f_{3}Pldz$$

(16)

$$F_4=F_{N5}-F_{N6}$$

(17)

where F₂ represents the pushing force exerted on the infinitesimal volume by the following material (N); F₃ represents the resistance exerted on the infinitesimal unit by the material ahead (N); F_f5 represents the frictional force on the surface of the baling cylinder (N); F_f6 represents the frictional force of the material above the infinitesimal element (N); F_N5 represents the normal pressure on the pressure surface of the spiral blade (N); F_f7 represents the frictional force on the bearing surface of the spiral blade (N); F_N6 represents the normal pressure on the back surface of the spiral blade (N); F_f8 represents the frictional force on the reverse side of the spiral blade (N); F_f9 represents the frictional force of the material below the infinitesimal element (N); F₄ represents the normal pushing force exerted on the infinitesimal unit by the advancing face (N); P represents the pressure acting on the infinitesimal element (Pa); h represents the height of the material (mm); z represents the transportation length of the material (mm); $\rho$ represents the density of the material (kg/m³); a_n represents the acceleration of the material (m/s²); f₁ represents the friction coefficient between the material and the baling cylinder; f₂ represents the friction coefficient between the material and the spiral blade and spiral shaft; and f₃ represents the internal friction coefficient between the materials.

The baling drum of the machine is designed with an inner diameter of 300 mm, a compression chamber length of 600 mm, and a feeding port size of 310 mm in length and 220 mm in width. The conveying and compaction capabilities of the baling and bagging mechanism are primarily influenced by the rotational speed of the helical shaft, the pitch, and the diameter of the helical blade. The main parameter relationships satisfy the following [37]:

$$Q=47{D_x}^2\lambda l\gamma n_x\epsilon$$

(18)

$$D_x\ge \phi \sqrt[2.5]{{\displaystyle \frac{Q}{\lambda \epsilon {\rho }_d}}}$$

(19)

$$d_x=\left(0.2~0.35\right)D_x$$

(20)

$$n<n_{max}={\displaystyle \frac{k}{\sqrt{D_x}}}$$

(21)

$$l=\left(0.5~2.2\right)D_x$$

(22)

In the above equations, D_x represents the external diameter of the spiral blade (mm); d_x represents the diameter of the spiral shaft (mm); l represents the screw pitch (mm); Q represents the conveying capacity (kg/h); n_x represents the rotational speed of the spiral shaft (rpm); λ represents the filling coefficient, set to 0.4; $\gamma$ represents the material characteristic coefficient [38]; ${\rho }_d$ represents the bulk density of the material (kg/m³); ε represents the inclined conveying coefficient, with a value of 1 for horizontal conveying; k represents the comprehensive characteristic coefficient of the material; $\phi$ represents the comprehensive characteristic coefficient of the silk-like corn stalks.

Silage density is a critical factor affecting nutrient retention, with a higher compaction density significantly reducing losses in bagged storage [39]. To further determine the feasibility of the bale packaging mechanism and to verify the quality of the screw conveyor in transporting shredded straw material and compacting it into a bale, a simulation of the bale packaging process was carried out using the discrete element method (DEM), providing a theoretical basis for parameters such as the screw conveyor rotation speed and feeding rate.

The shredded corn stalks have complex and diverse shapes. To reduce the complexity of the simulation calculations, the shapes and sizes of shredded corn stalks were simplified as shown in Figure 10. In the discrete element software EDEM 2022.3 (Altair Engineering Inc., Troy, MI, USA), the actual material of 12.5 mm × 2.0 mm × 2.0 mm [40] with a moisture content of 60% was selected. The bale packaging unit was modeled using SolidWorks 2022 (Dassault Systèmes, Vélizy-Villacoublay, France), then it was simplified and converted to STEP format to be imported into EDEM software. The simulation time was set to 6 s, with the feeding rate of shredded material matching the machine’s production capacity of 2500 kg/h. The time step for the DEM simulations was set to 4.12 × 10⁻⁶ s, which is approximately 20% of the Rayleigh time step, ensuring numerical stability while maintaining computational efficiency. The particle generation rate was calculated as 0.694 kg/s, and the initial velocity of particles entering the bale packaging mechanism was set to 5 m/s. The rotational speed of the screw shaft was 228 r/min. The Hertz–Mindlin no-slip contact model was used for the simulation particles, and the material property and contact parameters are listed in

Table 1. Material property parameters.

Attribute	Poisson’s Ratio	Shear Modulus/(Pa)	Density/(kg/m3)
Stalk material	0.4	1.1 × 107	420
Baling and bagging device	0.3	7 × 1010	7800

and

Table 2. Material contact parameters.

Contact Form	Restitution Coefficient	Coefficient of Static Friction	Coefficient of Rolling Friction
Stalk material—stalk material	0.2	0.7	0.01
Stalk material—baling and bagging device	0.2	0.4	0.01

[40,41]. To accurately capture the behavior of granular materials, rolling friction was incorporated into the model using the Standard Rolling Friction model in EDEM. This model is based on a linear rolling resistance formulation, where the rolling friction torque $T_r$ is calculated as follows [42]:

$$T_r=-{\mu }_r{R}_r{F}_r{\omega }_r$$

(23)

where ${\mu }_r$ is the coefficient of rolling friction, $R_r$ is the particle radius (mm), $F_r$ is the normal force (N), and ${\omega }_r$ is the unit angular velocity vector of the object at the contact point.

The DEM simulations were carried out on a workstation equipped with 32 CPU cores and 32 GB of memory. The total simulation time reached approximately 96 h, underscoring the computationally intensive nature of DEM. To validate the accuracy of the discrete element simulation model for silk-like straw materials, this study conducted both simulation and physical experiments using the cylinder lifting method to measure the angle of repose. The experiments were repeated five times, with the average angle of repose from the simulation being 36.63° and from the physical test being 35.19°, resulting in a relative error of 4.09%. These results demonstrate that the discrete element model for filamentous straw materials is highly accurate and reliable, effectively simulating the mechanical behavior of the actual material.

2.5. Equipment Performance Test Design

To verify the working performance of the canning-type silage feed crushing, raking, and bundling integrated machine and determine the optimal working parameter combination, performance tests were conducted at the Engineering Training Center of Gansu Agricultural University. The test conditions are shown in Figure 11. The test material comprised whole maize stalks placed in their natural state for about 15 days after harvesting and bundling. The average length of the stalks was 2400 mm, with an average moisture content of 60%. The root diameter ranged from 15 to 36 mm, the middle diameter from 10 to 29 mm, and the top diameter from 5 to 12 mm. The maximum diameter of the maize ears was 60 mm. The test instruments included silage bags, tape measures, vernier calipers, stopwatches, and electronic scales.

Based on the “NY/T 509-2015 Technical Specifications for Quality Evaluation of Straw Raking Machines” and “DG/T 053-2019 Hay Shredding Machines” [43,44], productivity Y₁ and raking rate Y₂ were chosen as evaluation indices. A three-factor, three-level experiment was designed using Box–Behnken central composite design theory, with the number of hammer blades X₁, hammer blade length X₂, and hammer head tilt angle X₃ as the experimental factors. The factor coding is shown in

Table 3. Test factors and levels.

Factor Level	Test Factor
	Number of Hammers X1/(piece)	Hammer Blade Length X2/(mm)	Hammer Head Tilt Angle X3/(°)
−1	24	50	0
0	28	80	15
1	32	110	25

.

The calculation of productivity Y₁ is shown as follows:

$$Y_1={\displaystyle \frac{S}{T}}$$

(24)

where S represents the amount of material processes during the operation time (kg) and T represents the duration of the operation (h).

The filamentation rate Y₂ is calculated using the following formula:

$$Y_2={\displaystyle \frac{W_a}{W_b}}\times 100\%$$

(25)

where W_a represents the mass of filamented straw in the sample (g) and W_b represents the mass of the sample (g).

3. Results and Discussion

3.1. Simulation Process of Bale Packaging and Results Analysis

To evaluate the compaction and forming effect of the silaged material, the Setup Selections function in the post-processing module of EDEM software was utilized to create a Grid Bin Group monitoring area. The actual mass of the compacted silage material within the model was monitored, and the data were extracted and converted to density to determine the density of the formed bale. The test results were compared with the “DG/T 043-2024 Baler” standard [45].

The density of the bale is calculated as

$$\begin{array}{c}{m}_d={\displaystyle \frac{m_q\left(1-G\right)}{\left(1-0.2\right)}}\\ V_q={\displaystyle \frac{1}{4}}\pi d_q^2{h}_q\\ {\rho }_q={\displaystyle \frac{m_d}{V_q}}\end{array}$$

(26)

where m_d represents the equivalent mass of the bale (kg); m_q represents the actual measured mass of the bale (kg); G represents the moisture content of the straw (%); ρ_q represents the compaction density of the bale (kg/m³); V_q represents the volume of the bale (m³); d_q represents the diameter of the silage bag (mm); and h_q represents the height of the silage bag (mm).

The simulation process of baling and bagging filamentous straw materials is illustrated in Figure 12. Figure 12a shows the linear flow of particles at 2 s, where initial particle accumulation in the silage bag is observed. Figure 12b shows the bale formation at 6 s of the simulation. According to the DEM simulation, the actual mass of the bale in the monitoring area reaches 3.00242 kg. By substituting into Equation (26), the bale density is calculated as 140.067 kg/m³. The bale density meets operational requirements, demonstrating that the mechanism can compress filamentous straw into cylindrical bales, successfully completing the baling process.

3.2. Equipment Performance Test

3.2.1. Results and Analysis

The test results for straw productivity Y₁ and the filamentation rate Y₂ are presented in

Table 4. Test indicator results.

Test Number	X1	X2	X3	Y1/(kg/h)	Y2/%
1	−1	−1	0	2453.21	88.92
2	1	−1	0	2425.48	91.10
3	−1	1	0	2489.91	92.63
4	1	1	0	2796.34	92.98
5	−1	0	−1	2340.16	88.16
6	1	0	−1	2624.22	92.35
7	−1	0	1	2398.31	91.91
8	1	0	1	2604.45	91.67
9	0	−1	−1	2366.53	87.32
10	0	1	−1	2532.43	91.56
11	0	−1	1	2320.60	87.93
12	0	1	1	2558.74	91.65
13	0	0	0	2664.55	92.19
14	0	0	0	2695.94	91.28
15	0	0	0	2739.26	92.74
16	0	0	0	2711.82	93.28
17	0	0	0	2643.69	92.52

.

The data in Table 4 were analyzed using quadratic regression equations and linear fitting to obtain the quadratic polynomial regression model for productivity Y₁ and silking rate Y₂ concerning the hammer quantity X₁, hammer blade length X₂, and hammerhead inclination angle X₃. Significance tests and variance analysis were conducted on the test factors to further identify the key factors affecting performance. The variance analysis results for productivity Y₁ and silking rate Y₂ are shown in

Table 5. Variance analysis.

Indicator	Source of Variance	Sum of Squares	Degrees of Freedom	Mean Square	F	p
Y1	Model	345,000	9	38,311.65	22.85	0.0002 ***
	X1	74,821.22	1	74,821.22	44.62	0.0003 ***
	X2	73,443.29	1	73,443.29	43.8	0.0003 ***
	X3	17,632.69	1	17,632.69	10.52	0.0142 **
	X1X2	27,915.73	1	27,915.73	16.65	0.0047 ***
	X1X3	1517.88	1	1517.88	0.91	0.3731
	X2X3	1304.65	1	1304.65	0.78	0.407
	X12	11,082.31	1	11,082.31	6.61	0.037 **
	X22	40,862.78	1	40,862.78	24.37	0.0017 ***
	X32	92,181.88	1	92,181.88	54.97	0.0001 ***
	Residual	11,738.31	7	1676.90
	Lack of Fit	6013.58	3	2004.53	1.40	0.3651
	Pure Error	5724.73	4	1431.18
	Cor Total	357,000	16
Y2	Model	53.36	9	5.93	10.75	0.0025 ***
	X1	7.5	1	7.50	13.6	0.0078 ***
	X2	22.3	1	22.30	40.45	0.0004 ***
	X3	6.6	1	6.60	11.98	0.0105 **
	X1X2	0.84	1	0.84	1.52	0.2576
	X1X3	4.91	1	4.91	8.9	0.0204 **
	X2X3	0.068	1	0.068	0.12	0.7365
	X12	0.18	1	0.18	0.33	0.5861
	X22	6.07	1	6.07	11.02	0.0128 **
	X32	10.59	1	10.59	19.21	0.0032 ***
	Residual	3.86	7	0.55
	Lack of Fit	1.66	3	0.55	1	0.4781
	Pure Error	2.2	4	0.55
	Cor Total	57.21	16

Note: *** indicates extremely significant effect (p ≤ 0.01); ** indicates significant effect (0.01 < p ≤ 0.05).

.

As shown in Table 5, the regression model for productivity Y₁ is extremely significant. The coefficient of determination R² is 0.9247, indicating that the regression model can explain 92.47% of the response value variation. The lack-of-fit term is not significant, suggesting small experimental error and good fitting of the regression equation. X₁, X₂, X₁X₂, X₂², and X₃² have extremely significant effects on productivity Y₁. X₃, X₁X₃, and X₂X₃ have significant effects, while other factors have no significant effects. The order of influence of the test factors on productivity Y₁ is hammer quantity X₁, hammer blade length X₂, and hammerhead inclination angle X₃. After excluding insignificant terms without losing fit, the final multivariate quadratic regression equation for productivity Y₁ is obtained, as follows:

$$Y_1=2686.55+99.36X_1+98.44X_2+43.06X_3+83.54X_1{X}_2-51.30X_1^2-98.51X_2^2-102.75X_3^2$$

(27)

From Table 5, it can be concluded that the regression model for the fiberization rate Y₂ is highly significant; the R² value of the model is 0.8458, indicating that the regression model can account for 84.58% of the variation in the response variable. The lack of fit is not significant, indicating small experimental errors and a good fitting of the regression equation. X₂, X₁, and X₃² significantly affect Y₂, while X₃, X₂², and X₁X₃ have a significant effect. Other factors do not significantly influence the fiberization rate. The order of influence on Y₂ is hammer blade length X₂, hammer number X₁, and hammer head tilt angle X₃. After eliminating the insignificant terms, the final multiple quadratic regression equation for Y₂ is as follows:

$$Y_2=92.28+0.99X_1+1.72X_2+0.83X_3-0.92X_1{X}_3-1.20X_2^2-1.10X_3^2$$

(28)

3.2.2. Parameter Optimization and Experimental Verification

To achieve the optimal parameter combination for the best operational performance, the multi-objective optimization algorithm in Design-Expert 10 (Stat-Ease Inc., Minneapolis, MN, USA) was employed. The optimization objectives were to maximize machine throughput and the straw fiberization rate. A mathematical model for optimization was established through analysis, identifying the optimal working parameters for the canning-style silage feed crushing, fiberization, and bundling machine as follows: 31.45 hammer blades, a hammer blade length of 99.16 mm, and a hammer head tilt angle of 14.12°. With these parameters, the machine achieved a throughput of 2806.05 kg/h and a fiberization rate of 93.62%.

To verify the reliability of the optimization results, the hammer blade number was adjusted to 32, the hammer blade length was rounded to 99 mm, and the hammer head tilt angle was rounded to 14°. The optimization results were validated through tests repeated five times. The average value of the five test results was taken as the actual value for the evaluation indicators under these conditions.

The compacted density of the straw bundles is primarily influenced by the friction coefficient of the compression chamber’s inner wall and the compression chamber length. For testing, the machine was configured with an inner wall friction coefficient of 0.5 and a compression chamber length of 600 mm. Performance tests were conducted based on the straw density testing method, with the results presented in

Table 6. Performance comparison table.

Indicator	Test Mean	Technical Requirement
Straw Fiberization Rate/%	94.28	≥90
Hay Bale Compression Density/(kg/m3)	124.52	≥100
Total Machine Productivity/(kg/h)	2815.29	≥2500

.

The verification test results indicate that, under the optimized parameter combination, the test outcomes align closely with the optimization results, confirming the reliability of the optimization process. Both the productivity and fiberization rate meet practical work requirements, suggesting that the optimized parameters represent the best working conditions for the silage feed crushing, fiberization, and baling integrated machine. During testing, the machine operated smoothly without significant feed blockages or jamming, and the noise level complied with the required standards.

4. Conclusions

To address the issues of clogging, labor-intensive manual loading, and poor sealing in existing small-scale pulverizing and fiberizing machines and balers used in hilly areas and small-scale planting regions, a canned silage feed crushing, fiberizing, and baling integrated machine was developed. This machine combines the functions of crushing, fiberizing, and baling into a single system.

The process begins with silage feed being transported and broken down by a chain conveyor and roll feeding mechanism. The feed is then flattened and fiberized in a pulverizing and fiberizing chamber before being compressed and bagged into silage bags by the baling mechanism. This integration improves the filling efficiency and automates the entire process.

Key components of the machine were systematically designed. Force and motion analyses were conducted for the feeding, fiberizing, and compression processes, leading to the determination of the structure and working parameters for the chain conveyor, roll feeding mechanism, pulverizing and fiberizing mechanism, and baling mechanism. Simulation tests of straw material compression and bagging showed that after six seconds of operation, the bale density reached 140.067 kg/m³, meeting the requirements for integrated filling operations.

Experimental tests were conducted to evaluate factors such as the number of hammers, hammer blade length, and hammer head angle, using productivity and fiberization rate as performance indicators. Variance analysis revealed the following influences:

For productivity, the number of hammers had the greatest impact, followed by hammer blade length and hammer head angle.

For the fiberization rate, hammer blade length was the most influential, followed by the number of hammers and hammer head angle.

The optimal parameters were found to be 32 hammers, a hammer blade length of 99 mm, and a hammer head angle of 14°. Under these conditions, the machine achieved a productivity of 2815.29 kg/h, a fiberization rate of 94.28%, and a bale density of 124.52 kg/m³. The machine operated smoothly, delivering high fiberization quality with no feed blockages, successfully meeting practical operational requirements.