Experimental Study on the Cutting and Crushing Performance of Caragana Korshinskii Strips

Abstract

Due to their characteristics, Caragana Korshinskii bars are prone to be crushed by kneaded crushed material, and the kneaded crushed material is prone to clogging the sieve, thus affecting the crushing effect. In this paper, we use the Caragana Korshinskii special hammer crusher to carry out the Caragana Korshinskii cutting and crushing test to study the influence of Caragana Korshinskii diameter, cutting length, and moisture content on the crushing effect of Caragana Korshinskii, and obtain the best process parameters through the response surface method. The results were as follows: When the diameter of Caragana Korshinskii strips was in the range of 6–9 mm, the length of the cut section was in the range of 4–8 cm, and the moisture content of Caragana Korshinskii strips was in the range of 10–19%, the Caragana Korshinskii strips crushing effect was the best, and the kneading situation was the lowest. The optimal Caragana Korshinskii crushing effect was achieved when the diameter of the Caragana Korshinskiibar was 6.5 mm, the length of the cut section was 8.4 cm, the moisture content was 19%, the sieve rate of 2 mm was 46.15%, the sieve rate of 4 mm was 66.32%, and the length of the kneaded wire was 3.3 cm.

1. Introduction

In addition to its role as a windbreak and sand trap, the shrubby plant Caragana Korshinskii has been found to have high nutritional value, with a protein content of 22.9%, fiber content of 27.8%, and calcium content of 4.9%. The branches of the Karaganda Kolsinski tree are crushed and transformed into pellet feed through pelleting. This can be utilized as a feedstock for livestock, such as cattle and sheep, thereby optimizing the inherent value of the Karaganda Kolsinski tree [1]. However, the Caragana Korshinskii itself has long branch fibers and a high degree of lignification, and it is relatively simple to produce kneading and agglomeration after crushing into grass powder. This makes it more difficult for the material to pass through the sieve, making crushing and pelleting more challenging. Among them, Caragana Korshinskii, in the crushing work, is prone to kneading, crushing is incomplete, and the branch is easily stuck in the crushing chamber. The sieve mesh and other conditions affect the crushing effect. In the actual crushing test, it can be found that, with the increase in branch diameter, its hardness increases, and the crushing effect is different. The cut length of Caragana Korshinskii is different, and the crushing process is subject to different kneading forces, thus affecting the crushing effect [2]. Caragana Korshinskii sticks are harvested at different times of the year, with varying moisture content. Following harvesting, they are used for crushing, resulting in different effects [3,4,5,6,7] The primary focus of research conducted by domestic scholars is the investigation of the material crushing process, particularly about the mechanical structure of the crushing device. This encompasses aspects such as the dimensions of the screen aperture, the configuration of the hammers, and the structural composition of the body [8,9,10,11,12]. Additionally, scholars such as He Ren Cai have conducted empirical studies to elucidate the relationship between material parameters (moisture content) and comminution efficiency [13]. Mou Xiaobin et al. and Wang Bokai et al. found that the number of hammers, the amount of feed, the feeding speed, and the moisture content of raw materials have a more significant effect on the crushing effect of the hammer mill [14,15]. Wu Tao et al. used fluid dynamics Fluent software to simulate the different structures of the crushing device; the results showed that improving the spindle speed can improve the crushing length of the qualified rate [16]. Zheng Shuhe et al. enhanced the efficiency of the crusher by devising a novel configuration for the hammer blades and modifying the thickness of the hammer blades [17]. Zhang et al. employed the CFD method and discovered that the arrangement of the hammer frames and blades, screens, and impellers within the crushing chamber of the crushing device can markedly enhance the crushing quality and the material conveying efficiency [18]. In an experimental study on the cutting characteristics of Caragana Korshinskii, Luo Haifeng et al. proposed the use of a concentric curved-edge slide cutter as a means of reducing the cutting force during the cutting process [19]. In a study conducted by Ma Xue Ting and colleagues, the impact of diverse tool configurations on the pulverization of forage straw was investigated across a range of rotational speeds. The findings revealed that the hob-type crushing structure exhibited the most effective pulverization at 2400 r/min [20]. The research of foreign scholars on the comminution process focuses more on the level of microscopic particle motion, exploring the periodic motion law of ellipsoidal particles, as well as the orientation and motion tendency of kneaded articulated particles [21,22]. Furthermore, scholars have investigated the relationship between cutting parameters and energy consumption, as well as the reliability of the machine and the factors that influence the likelihood of failure [23,24]. In their study, Philip Pichler et al. investigated the impact of varying levels of primary cutting force on a chipping drum producing wood chips and the influence of different tool angles on test wood, employing experimental measurements [25]. Lorenzo Fiorineschi et al. developed a novel approach to wood shredding that is capable of effectively processing wood with high moisture content [26]. Moritz Eisenlauer et al. investigated the effect of process parameters such as moisture content and the sieve width of internal grading sieves on the comminution of wood in hammer and chipping mills and found that hammer mills produced a wider particle size distribution and a higher proportion of fines than chipping mills [27]. This paper presents a synthesis of the research findings of domestic and foreign scholars, focusing on the challenges encountered in the process of Caragana Korshinskii crushing. To this end, it employs the existing hammer blade, the Caragana Korshinskii crusher, to conduct a series of crushing tests to identify the optimal crushing parameters for Caragana Korshinskii cut-off crushing.

2. Materials and Methods

2.1. Test Materials

The test material of Caragana Korshinskii trees used in this experiment was collected from Helinger County, Hohhot City, Inner Mongolia Autonomous Region, and was cut at the root and neck using pruning shears, with 5 branches cut from each plant, and 12 plants were sampled at each site, with a total number of 60 plants and 300 branches collected. After collection, branches were proportionally intercepted into 3 segments (bottom, middle, and top stems) and grouped for labeling. As shown in Figure 1.

A sample of the raw material collection area was taken, and the morphological characteristics of Karaganda Kolins were selected for determination. Ten Karaganda Kolins were chosen randomly, and one branch of each plant was randomly assigned to provide the basic parameters for the subsequent experiments. The specific results are shown in

Table 1. Measurement of morphological characteristics of Caragana Korshinskii plants.

Sample Number	High Level	Bottom Diameter	Centre Diameter	Top Diameter
1	160	19.4	16.7	11.4
2	135	17.1	12.5	7.3
3	115	12.5	11.0	6.8
4	126	15.0	13.7	8.1
5	132	13.2	11.6	6.8
6	124	12.9	11.8	8.0
7	132	17.1	12.0	7.7
8	166	20.6	16.2	10.6
9	156	16.8	15.5	11.7
10	92	11.3	11.3	6.7
Average value	133.8	15.59	13.23	8.51

.

2.2. Caragana Korshinskii Crushing Mechanism

We used hammer-crusher Caragana Korshinskii crushing; the material in the crushing chamber; and the knife’s role in the form of the main form of percussion crushing, impact crushing, and rubbing crushing. The Caragana Korshinskii material is mainly subjected to impact crushing and rubbing after entering the crushing box [28].

Impact crushing: The Caragana Korshinskii strips that have been cut off will impact with the high-speed rotating hammer blades when they enter the crushing chamber. Neglecting the disturbance of the airflow in the crushing chamber, the momentum theorem shows the following:

$$P∆t=m(v_1-v_2)$$

(1)

$$P={\displaystyle \frac{m(v_1-v_2)}{∆t}}$$

(2)

where P is the force of the hammer blade on the material, kg⋅m/s; m is the average mass of the material, kg; v₁ is the linear velocity of the hammer blade, m/s; and v₂ is the speed of the material before impact with the hammer blade, m/s.

From the above formula can be seen that, when the average mass of the material is unchanged, the higher the speed of the hammer blade, the shorter the collision time, and the better its crushing effect. That is, when the force on the material is greater than the unit strength of the material itself, the material is crushed.

After crushing is completed, the material will be under the action of the impact force of the high-speed impact of the tooth plate and sieve plate secondary collision that occurs, according to the momentum theorem:

$$N={\displaystyle \frac{m^{\prime }}{∆t_1}}(1+\lambda )v_{n}cos\alpha$$

(3)

where m′ is the average mass of the material when it is further crushed, kg; N is the impact force of the material and the toothed plate sieve plate, N; V_n is the impact velocity of the material unit, m/s; Δt₁ is the impact time, s; λ is the elastic recovery coefficient of the material; and α is the angle of incidence of the material on the impact surface.

From the above formula, it can be seen that the size of the impact force mainly depends on the elastic recovery coefficient and the speed before impact, and the elastic recovery coefficient of the material is mainly related to the moisture content. When the impact occurs, part of the material is crushed, and part rebounds.

Rubbing crushing: when the material in the crushing chamber cannot pass the screen plate, the material will remain in the crushing chamber, and the hammer blade teeth plate screen to rub the role; this is the main principle of hammer crusher-crushed materials. The rubbing force can be expressed as follows:

$$f_1={\mu }_1{F}_n$$

(4)

$$f_2={\mu }_2(m{\displaystyle \frac{v^2}{D+\delta }}+F_n)$$

(5)

where f1 and f2 are the material and toothed plate sieve plate and the inner wall of the force; u1 and u2 are the material and the hammer blade squeeze pressure, respectively; Fn is the material and the hammer blade material and the toothed plate sieve plate friction coefficient; m is the mass of the material particles, kg; v for the speed of the material particles, m/s; and D for the diameter of the cutter, m; δ for the diameter of the sieve plate, m.

Most of the material crushing will not be completed by the impact of the hammer blade, but through the continuous friction between the material and the hammer blade and screen plate to achieve the purpose of complete crushing. When the Caragana Korshinskii branch is subjected to the kneading action of the sieve on the Caragana Korshinskii branch, the force is balanced in the vertical direction, but it is subjected to the friction between the Caragana Korshinskii branch and the sieve in the horizontal direction, leading to the further destruction of the internal structure of the Caragana Korshinskii branch and the tearing and kneading of the Caragana Korshinskii branch. The stresses generated within the material during the collision and crushing process can be expressed as follows:

$${\sigma }_{max}=0.098{\left({\displaystyle \frac{m_1{m}_2}{m_1+m_2}}\right)}^{{\displaystyle \frac{1}{5}}}{v}^{{\displaystyle \frac{2}{5}}}{({\displaystyle \frac{1}{r_1}}+{\displaystyle \frac{1}{r_2}})}^{{\displaystyle \frac{3}{5}}}{\left({\displaystyle \frac{1-{\mu }_1}{E_1}}+{\displaystyle \frac{1-{\mu }_2}{E_2}}\right)}^{{-}_5^4}$$

(6)

where m₁ and m₂, respectively, are the material and tool mass, kg; E₁ and E₂, respectively, are the material and tool modulus of elasticity, Pa; μ₁ and μ₂ are the Poisson’s ratio of the two; v is the crushing of the material relative motion speed, m/s; r₁ and r₂ for the collision point at the radius of curvature, m.

Based on the above theoretical analyses, the main influencing factors of the collision-crushing process of Caragana Korshinskii can be determined. From the above formula, it can be seen that, the greater the positive stress, the easier it is to break the material; and the smaller the particle size of the Caragana Korshinskii material particles, the smaller the radius of curvature of the collision and the greater the positive stress that can be generated within the particles, so the length of the cut section and the diameter of the Caragana Korshinskii on the Caragana Korshinskii crushed to a certain degree have an influence on the effect of the Caragana Korshinskii crushing. From the above formula, we can see that for the brittle material, the smaller μ₁ is, the larger E is, and the easier it is to break the material; and the moisture content of the material has a certain effect on the brittleness of the material itself.

Based on the above analysis, the diameter of the Caragana Korshinskii, the length of the cut section, and the moisture content of the Caragana Korshinskii have a more obvious effect on its crushing effect, so this paper selects the above three influencing factors to carry out the Caragana Korshinskii crushing characteristics of experimental research and strives to obtain the optimal process parameters suitable for crushing Caragana Korshinskii.

2.3. Test Instruments and Equipment

2.3.1. Testing Instruments

The main equipment of the test: AR224CN electronic balance, OHAUS Instrument Co., Ltd., Changzhou, China; 150 mm range vernier caliper, Wuxi Xi gong Measurement Co., Wuxi, China; and DHG-9140A Blast-Drying Oven (maximum working temperature, 300 °C), Shanghai Shanzhi Instrument Co., Shanghai, China.

2.3.2. Experimental Equipment

The equipment used for the test was a Caragana Korshinskii special hammer chip crusher (motor power of 4.4 KW, spindle speed of 2880 r/min, and sieve aperture of 6 mm, hammer sieve clearance of 10–13 mm) The Hammer Chip Caragana Korshinskii Crusher comprises several key components, including a frame, feeding device, crusher main machine, crushed material conveying device, and fan. The feeding device is located at the upper portion of the primary apparatus of the aforementioned crusher. The primary apparatus is situated at the apex of the supporting structure, the device for conveying the crushed material is positioned at the base of the primary apparatus, and the fan is located on the left side of the device for conveying the crushed material. The structural schematic diagram is illustrated in Figure 2.

2.3.3. Working Principle

After the cutting of the Caragana Korshinskii strips was completed, the Caragana Korshinskii strips entered the crushing chamber through the feeder. The structure of the crushing chamber is shown in Figure 3a below: 201—sieve bottom support plate; 202—sieve blades; 203—blades; 204—hammer blade spacer; 205—hammer blades; 206—stirring rod; and 207—stirring rod. Upon entering the crushing chamber, the Caragana Korshinskii is subjected to a series of mechanical actions. The motor drives the main shaft and blades to rotate, while the hammers, situated between the two blades, also rotate, thereby facilitating the crushing of the material. Additionally, the stirring bar rotates in conjunction with the main shaft, contributing to the flocculation of the broken material.

Upon entering the crushing chamber through the feeding port (see Figure 3b), the Caragana Korshinskii branch assumes the position depicted in the figure. In the illustration, item 1 is the hammer blade, item 2 is the hammer frame plate, item 3 is the Caragana Korshinskii branch, and item 4 is the sieve hole. The Caragana Korshinskii is subjected to the radial impact force, F1, of the hammer blade, and the hammer blade and the Caragana Korshinskii branch are regarded as a single system. The system is only subjected to the impact force, F1, of the hammer blade on the Caragana Korshinskii branch and the reaction force, F2, of the Caragana Korshinskii branch on the hammer blade, as these forces are equal in magnitude and opposite in direction [29].

$$F_1={\displaystyle \frac{m_1\pi D\left(n_1-n_2\right)}{60∆t}}$$

(7)

The radial impact force of the hammer blade on the Caragana Korshinskii branch (F₁) is expressed in newtons (N). The mass of the hammer blade (m₁) is given in kilograms (kg). The diameter of the rotor (D) is expressed in millimeters (mm). The rotational speed of the crusher (n₁) before the interaction between the hammer blade and the Caragana Korshinskii branch is given in revolutions per minute (r). The rotational speed of the crusher after the interaction between the hammer blade and the Caragana Korshinskii branch is represented by n₂, in revolutions per minute (r/min). The time of the impact, Δt, is the duration of the hammer blade’s impact on the Caragana Korshinskii branch.

3. Design of the Experiment

3.1. Single-Factor Test

Univariate tests were conducted on the three factors of Caragana Korshinskii diameter, cutting length, and moisture content, respectively. The total weight of Caragana Korshinskii was 1 kg for each test, which was repeated five times at different levels of each factor. The sieving rate and kneading length of the 2 mm and 4 mm sieves were determined, respectively, and the results were averaged. The sieve rate is calculated according to Equation (7). The results were subsequently averaged. It should be noted that the diameter of Caragana Korshinskii twigs varies due to differences in their growth sites and ages. In this test, the different levels of twig diameter were formulated as follows. The diameter of the twigs was measured and categorized into the following ranges: 0–6 mm, 6–9 mm, 9–12 mm, 12–15 mm, and 15 mm and above. This was based on the diameter of the Caragana Korshinskii sticks, as measured in the field and presented in Table 1. According to the existing literature, the length of Karaganda Korshinskii tree branches was trimmed to 8–10 cm before the commencement of the crushing process. It was observed that the crushed Karaganda Kosinski tree material did not undergo appreciable kneading following the crushing operation. In this paper, in conjunction with previous studies, it is proposed that the five grades of shearing length be selected as 0–4, 4–8, 8–12, 12–16, and 16–20 cm, according to the findings of the aforementioned studies. The moisture content of the freshly collected Karaganda Kolsinski strips was found to be within the range of 26–30%. The Karaganda Kolsinski strips were subjected to air drying for 7 days, 15 days, 30 days, and an additional period of complete air drying. The resulting moisture content was found to be 20–25%, 10–19%, 6–8%, and 0–1%, respectively. For purposes of reference, the three levels of each factor and a single factor are presented in

Table 2. The selected factors and levels for the Single-Factor Test.

Factor/Level	Diameter of Sandy Caragana Korshinskii (mm)	Cut Length (cm)	Water Content (%)
1	0–6	0–4	26–30
2	6–9	4–8	20–25
3	9–12	8–12	10–19
4	12–15	12–16	6–8
5	>15	16–20	0

.

$$C={\displaystyle \frac{\left(m-m_1\right)}{m}}$$

(8)

where C is the sieving rate, %; m₁ is the mass of the Korshinskii grass powder not sieved through the sieve after sieving, g; and m is the mass of the Korshinskii grass powder crushed out, g.

3.2. Multi-Factor Test

To optimize the interaction between the levels and the factors tested, namely three factors, the three-level test was designed based on a one-factor experiment, and the factors and corresponding levels of the multifactor test are listed in

Table 3. The selected factors and levels for the orthogonal tests.

Level	Factors
	(A) Caragana Korshinskii Diameter/mm	(B) Length of Caragana Korshinskii Cut/cm	(C) Water Content of Caragana Korshinskii/%
1	0–6	0–4	0–1
2	6–9	4–8	6–8
3	9–12	12–16	10–19

.

3.3. Response Surface Test Analysis

A response surface analysis was carried out on the orthogonal test results using Design-Expert 13 software to derive the quantitative significance of the effects of each test factor on the evaluation indexes, the multiple regression equations, and response surface plots between the test factors and the evaluation indexes, and ultimately to obtain the optimal combinations of crushing process parameters for Caragana Korshinskii bars. The diameter, cutting length, and moisture content of Caragana Korshinskii bars were selected as the three test factors, and the 2 mm sieving rate, 4 mm sieving rate, and kneading length were selected as the three evaluation indexes; and after combining these parameters and factors with the results of the orthogonal test, the response surface-analysis factor levels were designed (

Table 4. Orthogonal test factor-level table.

Level	Factors
	(A) Caragana Korshinskii Diameter/mm	(B) Length of Caragana Korshinskii Cut/cm	(C)Water content of Caragana Korshinskii/%
−1	0–6	0–4	0–1
0	6–9	4–8	6–8
1	9–12	12–16	10–19

).

4. Results and Discussion

4.1. Single-Factor Test Results

A one-way experiment was carried out on the selected materials to study the effect of Caragana Korshinskii bar diameter on the crushing effect; the length of the cut section was selected from a range from 16 to 20 cm, and the moisture content was from 26% to 30%. The results of the test are shown in

Table 5. Single-factor test factor-level table.

(a)
Test Number	Caragana Korshinskii Diameter (mm)	Cut Length (cm)	Water Content (%)	Sieving Rate (%)		Kneading Length (cm)
				2 mm Sieve	4 mm Sieve
1	0–6	16–20	26–30	32.98	54.07	3–11
2	6–9			41.32	62.80	4–13
3	9–12			48.44	64.72	6–12
4	12–15			44.78	61.70	6–13
5	>15			42.28	59.86	9–19
(b)
Test Number	Caragana Korshinskii Diameter (mm)	Cut Length (cm)	Water Content (%)	Sieving Rate (%)		Kneading Length (cm)
				2 mm Sieve	4 mm Sieve
1	6–9	0–4	26–30	49.15	66.59	0–3.7
2		4–8		48.82	65.65	3–6.9
3		8–12		42.54	59.21	5–11
4		12–16		46.42	66.51	5–15.5
5		16–20		44.66	66.47	7–17.5
(c)
Test Number	Caragana Korshinskii Diameter (mm)	Cut Length (cm)	Water Content (%)	Sieving Rate (%)		Kneading Length (cm)
				2 mm Sieve	4 mm Sieve
1	9–12	8–12	26–30	37.81	57.29	7–11.7
2			20–25	42.02	55.81	4–10.3
3			10–19	42.97	60.90	3.3–5.7
4			6–8	43.12	60.40	0
5			0–1	41.53	61.47	0

(a), and the trend graph of the effect of Caragana Korshinskii bar diameter is shown in Figure 4. The accumulation of material within the sieve following the crushing of Korshinskii bars of varying diameters, as well as the sieving process itself, is illustrated in Figure 5, Figure 6, Figure 7, Figure 8 and Figure 9 below. When studying the effect of the cutting length on the crushing effect, the diameter of the Caragana Korshinskii bars was chosen to be 6~9 mm, and the moisture content was 26~30%; the test results are shown in Table 5 (b), and the trend graph of the effect of cutting length is shown in Figure 10. The accumulation of debris within the sieves following the crushing of Korshinskii bars of varying cutting lengths, along with the sieving outcomes, is illustrated in Figure 11, Figure 12, Figure 13, Figure 14 and Figure 15 below. To study the effect of the moisture content on the crushing effect, the cut-off length was chosen to be 8~12 cm, and the diameter of the Caragana Korshinskii bars was chosen to be 9~12 mm. The test results are shown in Table 5 (c), and the trend graph of the effect of moisture content is shown in Figure 16. The sieve-clogging and -sieving results of crushed the Korshinskii bars with varying moisture contents are presented in Figure 17, Figure 18, Figure 19, Figure 20 and Figure 21 below.

As can be seen from the above charts, the analysis of the influence of the test factors on the crushing results according to the influence law yielded the following results: The Caragana Korshinskii strip diameter in the range of 9~12 mm had the best Caragana Korshinskii strip crushing effect is the best; its rate through the 2 mm and 4 mm sieves was higher, i.e., 48.44% and 64.72%, respectively; and the particles of the kneading length were shorter. The diameter of 0~9 mm crushed within the crushing effect was better. The crushing result for the particulate matter was less kneaded silk material, so pre-selected fixed Caragana Korshinskii bar diameters of 0~6 mm, 6~9 mm, and 9~12 mm were chosen for the orthogonal test of the three levels. The Caragana Korshinskii cutting length of 0~4 cm had the best crushing effect; its 2 mm and 4 mm sieve rates were higher, with the highest being 49.15 per cent and 66.59 per cent; and the particles of kneading length were shorter for 0~3.7 cm, 4~8 cm, and 12~16 cm, indicating that the crushing effect is better, and the crushing result is more particles and less kneaded silk, so the pre-selected lengths of the Caragana Korshinskii cut section are 0~4 cm, 4~8 cm, and 12~16 cm for the three levels of the orthogonal test. The best crushing effect was achieved when the moisture content of the Caragana Korshinskii strips was in the range from 10 to 19 per cent, with sieving rates of 40.97 per cent and 60.90 per cent for 2 mm and 4 mm, respectively, and kneading lengths from 3.3 to 9.7. In 0~10%, the crushing effect was better, and the crushing results were more needles and less kneading silk material, so we selected Caragana Korshinskii water contents of 0~1%, 6~8%, and 10~19% for the orthogonal three-level test.

4.2. Multi-Factor Test Results

To further investigate the optimum crushing process parameters for crushing Caragana Korshinskii bars, based on the optimum levels selected from the results of the mentioned one-way test, a table of factor levels is presented in Table 2. The specific experimental results are shown in

Table 6. Test scheme and test results.

Test Number	A	B	Blank Column	C	Sieving Rate (%)		Kneading Length (cm)
					2 mm Sieve	4 mm Sieve
1	1	1	1	1	39.18	65.80	0
2	1	2	2	2	36.89	60.23	0
3	1	3	3	3	40.09	65.26	13.5
4	2	1	2	3	49.15	66.59	3.8
5	2	2	3	1	43.72	68.18	0
6	2	3	1	2	38.46	59.90	15.5
7	3	1	3	2	40.78	63.58	3.8
8	3	2	1	3	40.99	59.83	7.1
9	3	3	2	1	45.64	71.17	0

. Following the completion of the orthogonal test, the results of the clogging of the sieves and the sieving of the Caragana Korshinskii grass powder discharged from the crusher are presented in Figure 22, Figure 23, Figure 24, Figure 25, Figure 26, Figure 27, Figure 28, Figure 29, Figure 30 and Figure 31 respectively.

According to the table of orthogonal tests used to conduct the orthogonal tests, it can be seen that when the diameter of Karaganda Kolsinski grass is kept in the lowest range, the length of the cut sections and moisture content increase appropriately, and after crushing, the Karaganda Kolsinski grass powder discharged from the crusher is mostly granular and acicular, which in this case is due to the fact that the length of the cut sections is too short and no kneaded particles have been formed; the crusher room is not clogged. When the diameter was kept in the lowest range and the cut length and moisture content were increased to the intermediate level, the increase in cut length and moisture content resulted in a large number of kneaded particles in the pulverized Caragana Korshinskii grass powder and a large number of kneaded particles clogged on the sieve. When the diameter is in the range of 6~9 mm, the length of the cut section and moisture content is at the lowest level, and the Caragana Korshinskii grass powder discharged after crushing is mostly needle-like crushed material, there is no blockage in the crushing chamber. At this time, although no kneading occurs, the needle-like crushed material cannot be used as the raw material for compression molding either. When the diameter is in the range of 6~9 mm, the kneading length and kneading efficiency of the kneaded crushed material will increase with the increase in the length of the cut section and the moisture content. The Caragana Korshinskii grass powder discharged after crushing passes through the sieve, but there is still a small portion of kneaded particulate matter. When the diameter is in the range of 9~12 mm, due to the diameter of the branch, the hardness is too large; at this time, the cut length and moisture content on its impact are weaker than the diameter of the effect, but when the moisture content is in the range of 0~1%, the crushed Caragana Korshinskii grass powder is still needle-like crushed material and does not appear to knead the silk of the situation, so it can be discharged smoothly from the crushing chamber.

The results of Table 6 were visually analyzed to derive the primary and optimal solutions for each experimental factor, and the experimental results are shown in

Table 7. Analysis of test results.

Targets		A	B	Blank Column	C
2 mm sieve ratio/%	K1	116.16	129.11	185.53	128.54
	K2	131.33	121.60	126.82	116.13
	K3	127.41	124.19	197.02	130.23
	k1	38.72	43.04	61.84	42.85
	k2	43.78	40.53	42.27	38.71
	k3	42.47	41.40	65.67	43.41
	Extreme difference, R	15.17	7.51	70.20	14.1
	Factor primary and secondary	ACB
	preferred solution	A2C3B1
4 mm sieve ratio/%	K1	191.29	195.97	185.53	205.15
	K2	194.67	188.24	197.99	183.71
	K3	194.58	196.33	197.02	191.68
	k1	63.76	65.32	61.84	68.38
	k2	64.89	62.75	66.00	61.24
	k3	64.86	65.44	65.67	63.89
	Extreme difference, R	3.38	8.09	12.46	21.44
	Factor primary and secondary	CBA
	preferred solution	C1B3A2
Kneading length/mm	K1	13.50	7.60	22.60	0.00
	K2	19.30	7.10	3.80	19.30
	K3	10.90	29.00	17.30	24.40
	k1	4.50	2.53	7.53	0.00
	k2	6.43	2.37	1.27	6.43
	k3	3.63	9.67	5.77	8.13
	Extreme difference, R	8.40	21.90	18.80	24.40
	Factor primary and secondary	CBA
	preferred solution	C3B3A2

.

From the results of Table 7, it can be seen that for different evaluation indicators, the degree of influence of different factors is not the same. Through the integrated balancing method to obtain the preferred program, the integrated balancing analysis is as follows:

Factor A (Caragana Korshinskii diameter) was at the optimal level of A2 for all three indicators, so A2 was selected as the superior solution for factor A (Caragana Korshinskii diameter). In addition, for these three indicators and the actual crushing results, factor A (Caragana Korshinskii bar diameter) had a significantly lower influence on whether or not kneading occurred than factor B (cut length) and factor C (moisture content). In regard to factor B (cut length) for the 2 mm sieve rate and the 4 mm sieve rate, B1 and B3 are basically the same, but when considering the kneading length, B3 is better. For the comprehensive analysis of the three indicators, we see that factor B (cut length), for the overall crushing results, has a significant impact, but also by the direct impact of the factor C (moisture content), When B1 is selected as the B factor, the short length of the factor results in the material obtained from crushing being mostly in the form of needles and flakes when the moisture content is too low, while the kneading of the material obtained from crushing is significantly greater than that in B2 when the moisture content is too high, so the B factor selected should be B2 in order to provide a better solution. Factor C (moisture content) for the 2 mm sieving rate and kneading length should be C3 for the optimal level, and for the 4 mm sieving rate, factor C should be C1 for the optimal level, and the reason for this is that the 4 mm sieve aperture is too large; when the moisture content of the C1 level of pulverized material is mostly needle-like pulverized material, and its C3 level of pulverized material is in the form of grass powder, the kneading pulverized material is dominated by the result that the 4 mm sieving rate is the more optimal solution in C1, combined with the eyes of the crushing results analysis. After a comprehensive review, it appears that C3 should be selected as the factor C (moisture content) for the best solution.

In summary, the preferred solution should be C3B2A2, i.e., from 10% to 19% water content for the Caragana Korshinskii, from 4 cm to 8 cm length of the Caragana Korshinskii cut section, and from 6 mm to 9 mm diameter of the Caragana Korshinskii branch.

4.3. Response Surface Test Results

4.3.1. Regression Modelling and ANOVA for the Three Factors

To further analyze the influence law of the experimental factors on the evaluation indexes and explore whether there is a better combination of crushing process parameters outside the orthogonal test level, a response surface test was conducted on the results of the orthogonal experiments, and the results are as follows:

The experimental results were processed and analyzed using Design-Expert 13 software, and the response surface analysis scheme and results are shown in

Table 8. Box–Behnken experimental design and results.

Serial Number	Diameter A (mm)	Cut Length B (cm)	Water Content C (%)	2 mm Sieve Pass Rate (%)	4 mm Sieve Pass Rate (%)	Kneading Length (cm)
1	0	−1	−1	43.02	63.29	0
2	0	0	0	40.03	56.21	6.3
3	−1	1	0	40.72	53.8	7
4	0	1	1	45.18	56.45	10.4
5	0	0	0	40.36	56.12	5.8
6	0	1	−1	41.1	62.19	0
7	−1	−1	0	41.93	58.77	3.3
8	0	0	0	39.98	56.31	6.3
9	0	−1	1	46.15	66.59	3.8
10	1	0	−1	41.67	61.58	0
11	1	−1	0	40.78	63.58	3.8
12	1	1	0	40.22	57.84	8
13	0	0	0	40.07	55.70	6.2
14	−1	0	1	45.19	55.27	5.4
15	1	0	1	40.99	59.83	7.1
16	0	0	0	40.19	56.04	5.9
17	−1	0	−1	37.74	56.02	0

.

Data processing of the results obtained from the orthogonal test leads to a quadratic multinomial regression equation, Equation (9), with the Caragana Korshinskii strip diameter, A; cut length, B; and moisture content, C, as variables and the 2 mm sieve rate (Y1) as the objective function.

Y1 = 40.13 − 0.24A − 0.5825B + 1.75C + 0.1625AB − 2.03AC + 0.2375BC − 0.8393A2 + 1.63B2 + 2.11C2

(9)

The results of the ANOVA for the 2 mm sieving rate are shown in

Table 9. Analysis of variance results for the 2 mm screening-rate response surface regression model.

Source	Sum of Squares	df	Mean Square	F-Value	p-Value	Significance
Model	77.65	9	8.63	118.05	<0.0001	**
A	0.4608	1	0.4608	6.31	0.0403	*
B	2.71	1	2.71	37.14	0.0005	**
C	24.43	1	24.43	334.29	<0.0001	**
AB	0.1056	1	0.1056	1.45	0.2684
AC	16.52	1	16.52	226.11	<0.0001	**
BC	0.2256	1	0.2256	3.09	0.1223
A2	2.97	1	2.97	40.58	0.0004	**
B2	11.13	1	11.13	152.28	<0.0001	**
C2	18.76	1	18.76	256.69	<0.0001	**
Residual	0.5116	7	0.0731
Lack of fit	0.4191	3	0.1397	6.04	0.0575	Not significance
Pure error	0.0925	4	0.0231
Cor total	78.16	16

Note: * indicates a significant difference (p < 0.05); ** indicates a highly significant difference (p < 0.01).

.

The results of ANOVA for the 2 mm sieve rate in

Table 10. Analysis of variance results for 4 mm screening-rate response surface regression model.

Source	Sum of Squares	df	Mean Square	F-Value	p-Value	Significance
Model	211.53	9	23.50	361.98	<0.0001	**
A	44.98	1	44.98	692.81	<0.0001	**
B	60.23	1	60.23	927.57	<0.0001	**
C	3.05	1	3.05	46.98	0.0002	**
AB	0.1482	1	0.1482	2.28	0.1746
AC	0.2500	1	0.2500	3.85	0.0905
BC	20.43	1	20.43	314.66	<0.0001	**
A2	2.48	1	2.48	38.13	0.0005
B2	42.80	1	42.80	659.19	<0.0001	**
C2	34.58	1	34.58	532.58	<0.0001	**
Residual	0.4545	7	0.0649
Lack of fit	0.2372	3	0.0791	1.46	0.3526	Not significance
Pure error	0.2173	4	0.0543
Cor total	211.98	16

Note: ** indicates a highly significant difference (p < 0.01).

are as follows: the F-values of the Caragana Korshinskii cut length and moisture content are <0.01, so their effects on the 2 mm sieve rate were highly significant, and the F-value of the Caragana Korshinskii diameter was <0.05, so their effects on 2 mm sieve rate were significant. In the two-by-two interaction effect test, the interaction between the Caragana Korshinskii diameter and moisture content F-value < 0.01 had a highly significant effect on the 2 mm sieve rate, and the interaction between the Caragana Korshinskii diameter and cut length and the Caragana Korshinskii cut length and moisture content F-value was >0.05, so its effect on the 2 mm sieve rate was not significant.

Data processing of the results obtained from the orthogonal tests resulted in a quadratic multinomial regression equation, Equation (10), with the Caragana Korshinskii bar diameter, A; cut length, B; and moisture content, C, as variables and the 4 mm sieve rate (Y2) as the objective function.

Y2 = 56.08 + 2.37A − 2.74B − 0.6157C − 0.1925AB − 0.25AC − 2.26BC − 0.7668A2 + 3.19B2 + 2.87C

(10)

The results of the ANOVA for the 4 mm sieving rate are shown in Table 10.

Table 10 shows that the Caragana Korshinskii bar diameter, cut length, and moisture content have an F-value < 0.01, so the effect on the 4 mm sieve rate was highly significant. In the two-by-two interaction effect test, the interaction between the length of the cut section of Caragana Korshinskii and the moisture content was an F-value < 0.01, so its effect on the sieve rate of 4 mm was highly significant. The interaction between the diameter of Caragana Korshinskii, the length of the cut section of Caragana Korshinskii, the diameter of Caragana Korshinskii, and the moisture content of Caragana Korshinskii was an F-value > 0.05, so its effect on the sieve rate of 4 mm was not significant.

Data processing of the results obtained from the orthogonal test resulted in a quadratic multinomial regression equation, Equation (11), with the Caragana Korshinskii bar diameter, A; cut length, B; and moisture content, C, as variables and the kneading length (Y3) as the objective function.

Y3 = 6.1 + 0.4A + 1.81B + 3.34C + 0.125AB + 0.425AC + 1.65BC − 0.5A2 − 0.075B2 − 2.48C

(11)

The results of the ANOVA for kneading length are shown in

Table 11. The results of variance analysis of response surface regression model of drawing length.

Source	Sum of Squares	df	Mean Square	F-Value	p-Value	Significance
Model	156.06	9	17.34	152.20	<0.0001	**
A	1.28	1	1.28	11.24	0.0122	*
B	26.28	1	26.28	230.68	<0.0001	**
C	89.11	1	89.11	782.17	<0.0001	**
AB	0.0625	1	0.0625	0.5486	0.4830
AC	0.7225	1	0.7225	6.34	0.0399	*
BC	10.89	1	10.89	95.59	<0.0001	**
A2	1.05	1	1.05	9.24	0.0189	*
B2	0.0237	1	0.0237	0.2079	0.6622
C2	25.79	1	25.79	226.39	<0.0001	**
Residual	0.7975	7	0.1139
Lack of fit	0.5775	3	0.1925	3.50	0.1288	Not significance
Pure error	0.2200	4	0.0550
Cor total	156.86	16

Note: * indicates a significant difference (p < 0.05); ** indicates a highly significant difference (p < 0.01).

.

4.3.2. Analysis of Primary and Secondary Influencing Factors for Each Test Indicator

According to the F-value in the results of the ANOVA of the regression model for each of the abovementioned test indicators, the magnitude of the influence of each factor on the test indicators can be obtained, as shown in

Table 12. Analysis of the influence degree of each factor on the test index.

Test Indicators	Degree of Influence of the Factors on the Test Indicators			Ranking of Impact
	A	B	C
Y1	6.31	692.81	11.24	B > C > A
Y2	37.14	927.57	230.68	B > C > A
Y3	334.29	46.98	782.17	C > A > B

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4.3.3. Analysis of the Effect Pattern of the Interaction of the Test Factors on the Evaluation Indicators

The interaction effects of the test factors on the 2 mm sieving rate were as follows (Figure 31): From Figure 31a, it can be seen that, when the moisture content of Caragana Korshinskii bars was controlled at a certain level, the 2 mm sieving rate showed a tendency to increase and then decrease with the increase in the diameter of the Caragana Korshinskii bars, A, and showed a tendency to decrease and then increase with the increase in the length of the cut section, B. The results were as follows: From Figure 31b, it can be concluded that by controlling the length of the cut section of Caragana Korshinskii bars at a certain level, the 2 mm sieving rate showed an increasing trend as the diameter of Caragana Korshinskii bars, A, increased, and the 2 mm sieving rate also showed an increasing trend as the moisture content, C, increased. From Figure 31c, it can be concluded that by controlling the diameter of Caragana Korshinskii bars at a certain level, the 2 mm sieve rate showed an increasing trend with the increase in moisture content, C, while the 2 mm sieve rate also showed an increasing trend with the increase in the length of the cut section, B, but the rate of increase was lower than that of the effect of moisture content on the 2 mm sieve rate.

The effect of the interaction of the test factors on the 4 mm sieve rate was as follows (Figure 32): From Figure 32a, it can be concluded that, by controlling the moisture content of the Caragana Korshinskii strips at a certain level, with the increase in the diameter of Caragana Korshinskii strips, A, the 4 mm sieve rate showed a slow increasing trend, and with the increase in the length of the cut section, B, the 4 mm sieve rate showed a decreasing trend, followed by an increasing trend. From Figure 32b, it can be concluded that by controlling the cutting length of Caragana Korshinskii strips at a certain level, with the increase in Caragana Korshinskii strip diameter, A, the 4 mm sieving rate showed a slowly increasing trend, and with the increase in moisture content, C, the 4 mm sieving rate showed a decreasing trend and then an increasing trend, and the interaction between the Caragana Korshinskii strip diameter and moisture content had a relatively gentle effect on the 4 mm sieving rate. From Figure 32c, it can be concluded that by controlling the diameter of Caragana Korshinskii bars at a certain level, the 4 mm sieve rate showed an increasing trend with the increase in moisture content, C, while with the increase in the length of cut section, B, the 4 mm sieve rate then showed a decreasing trend, followed by an increasing trend, but the rate of increase was lower than the effect of moisture content on the 4 mm sieve rate.

The interaction effects of the test factors on the kneading length were as follows (Figure 33): From Figure 33a, it can be concluded that by controlling the moisture content of the Caragana Korshinskii strips at a certain level, the kneading length showed an increasing trend as the diameter of the Caragana Korshinskii strips, A, increased, and the kneading length also showed an increasing trend as the length of the cut section, B, increased. From Figure 33b, it can be seen that by controlling the cut length of Caragana Korshinskii strips at a certain level, the kneading length showed a flat trend as the diameter of Caragana Korshinskii strips, A, increased, and the kneading length showed an incremental trend as the moisture content, C, increased. From Figure 33c, it can be concluded that by controlling the diameter of Caragana Korshinskii bars at a certain level, the kneading length showed an increasing trend with the increase in moisture content, C, while the kneading length also showed a slowly increasing trend with the increase in cutting length, B, but the growth rate was lower than that of the effect of moisture content on the kneading length.

In summary, using the Optimization module in the Design-Expert 13 software to optimize the parameters of the regression model of the test, factor A, the Caragana Korshinskii bar diameter, is set to be within the range of 0–12 mm; factor B, the cutting length, is set to be within the range of 0–16 cm; factor C, the moisture content, is set to be within the range of 6%-19%; the evaluation indexes of the 2 mm sieving rate and 4 mm sieving rate are set to the maximum value; and the kneading length is set to the minimum value. The rate is set as the maximum value, and the kneading length is set as the minimum value, creating a better parameter combination that can be obtained after solving. The optimal set of process parameters is highly consistent with the optimal process parameter scheme obtained by analyzing the results of the orthogonal test when the diameter of Caragana Korshinskii bars is 6.50 mm, the length of cut section is 8.4 cm, the moisture content is 19%, the sieve rate of 2 mm is 46.15%, the sieve rate of 4 mm is 66.32%, and the length of kneaded wire is 3.3 cm.

To resolve the issue of obtaining a lengthy shredded product when pulverizing the entire Caragana Korshinskii rind, this study proposes a method for cutting Caragana Korshinskii bars into segments and then crushing them. To assess the rationality and feasibility of this method, this study combines theoretical insights and experimental validation in a comprehensive analysis. In contrast to the papers of other experts and scholars who have analyzed the improvement of the mechanical structure, this paper analyzes the characteristics of the Caragana Korshinskii bars. It was found that controlling the cut length, diameter, and water content of the Caragana Korshinskii bars could lead to a reduction in the kneading that occurs during the crushing of Caragana Korshinskii bars. This theoretical basis provided the basis for subsequent experimental work. Through extensive crushing experiments, a series of crushing process parameters were identified that were effective in reducing the incidence of kneading and shortening the duration of kneading. This fills an important gap in problem-solving in the field of Caragana Korshinskii bar-crushing and -kneading research in favor of the Caragana Korshinskii bar industry. This is important for the industrial development of Caragana Korshinskii bars and the sustainable use of renewable energy.

5. Conclusions

(1)

Three factors, the Caragana Korshinskii diameter, cutting length, and moisture content, were selected to carry out a one-way test, and the results were as follows: when the diameter of Caragana Korshinskii was in the range of 9–12 mm, the cutting length of Caragana Korshinskii was in the range of 0–4 cm, and the moisture content of Caragana Korshinskii was in the range of 10–19%, the Caragana Korshinskii crushing effect was the best, and the kneading situation was the lowest.

(2)

The optimal levels of the three factors selected in the single-factor test were screened out, and a three-factor, three-level factorial orthogonal test was carried out, with the following results: the crushing effect was best when the diameter of the Caragana Korshinskii branches was within the range from 6 mm to 9 mm, the length of the cut section was within the range from 4 cm to 8 cm, and the moisture content was within the range from 10% to 19%, and the rubbing of the threads was effectively controlled.

(3)

Response surface analysis was carried out using Design-Expert 13 software, and the results were as follows: when the diameter of the Caragana Korshinskii bar was 6.5 mm, the length of the cut section was 8.4 cm, and the moisture content was 19%, the sieve rate of 2 mm was 46.15%, the sieve rate of 4 mm was 66.32%, and the kneaded length was 3.3 cm, which had the best crushing effect at this time.