Design and Performance Testing of Seed Potato Cutting Machine with Posture Adjustment

Abstract

In China, potatoes are predominantly cultivated using the tuber piece planting method. During the cutting process, it is essential to divide seed potatoes into tuber pieces based on the distribution of their bud eyes, ensuring that each tuber piece contains one to two bud eyes. These tuber pieces are subsequently sown into the soil. Currently, the preparation of potato tuber pieces relies heavily on manual labor, which presents challenges such as inefficiency and high operational costs. To address these issues, a seed potato cutting machine capable of posture adjustment, cutting, and spraying was designed. Three types of seed potato cutters were developed based on the distribution patterns of bud eyes. The movement mechanism of the posture adjustment process was analyzed, and a mathematical model was established. The key factors influencing the posture adjustment effectiveness were identified through discrete element simulation analysis. Using the qualified rate of potato cutting and the blind eye rate as evaluation metrics, a three-factor, three-level, orthogonal experimental design was implemented. The experimental factors included the rotational speed of the conical roller, the number of conical rollers, and the cutting angle. For the straight-shaped cutter, the optimal combination was determined as follows: a conical roller speed of 12 r/min, 44 conical rollers, and a cutting angle of 0°, yielding a qualified rate of 90.3% and a blind eye rate of 1.86%. For the Y-shaped cutter, the optimal parameters were 14 r/min, 44 conical rollers, and a 5° cutting angle, achieving a qualified rate of 87.9% and a blind eye rate of 2.86%. The cross-shaped cutter performed best at 14 r/min, 44 conical rollers, and a 0° cutting angle, with a qualified rate of 87.1% and a blind eye rate of 3.80%. All optimal configurations met agronomic requirements, demonstrating the efficacy of the designed machine and cutters.

1. Introduction

Currently, there are notable differences in the agronomic requirements for seed potato planting between China and developed countries. In European and American countries, the predominant practice involves the utilization of whole seed potatoes for breeding and planting, with a relatively low proportion of cut pieces. The primary advantage of whole seed potato planting lies in its capacity to reduce the complexity of manual operations and decrease labor costs. However, this approach is associated with higher seed potato costs.

In China, potato cultivation primarily employs the seed cutting method rather than whole-seed planting. Compared to whole-seed planting, seed cutting reduces seed consumption while enhancing germination rates [1]. As a core process, the quality of seed-cutting directly influences the potato yield [2,3,4,5]. Currently, manual cutting remains the predominant method in China, characterized by a low efficiency and inconsistent cutting quality, which significantly hinders the development of the potato industry [6].

Developed countries, such as those in Europe and the United States, have led global research on potato seed cutting machinery. For example, Belgium’s DEWULF Company [7], Canada’s Double L Company [8,9], and the U.S.’s Milestone Company [10] have developed advanced multi-functional seed cutting machines capable of automated feeding, grading, orientation adjustment, cutting, and spraying. However, these machines are often associated with complex manufacturing processes, high maintenance costs, and designs tailored to the whole-seed planting systems prevalent in their regions. Consequently, they are not well suited to meet the specific seed cutting requirements of China’s cultivation practices [11,12,13,14,15].

Domestically, researchers have made significant progress in the development of seed potato cutting machinery. For instance, Lv Jinqing et al. [16] designed a collaborative transverse and longitudinal cutting device for seed potatoes, which incorporated a secondary cutting function to enhance the cutting efficiency and the qualified rate of potato cutting. Similarly, Wang Xiangyou et al. [17] developed an oriented-arrangement transverse–longitudinal cutting machine that integrated functions such as impurity removal, sorting, alignment, cutting, and disinfection. This innovation represented a breakthrough in China’s efforts to advance in large-scale mechanized potato cutting equipment.

In China, significant advancements have been made in the development of seed potato cutting machinery. However, testing has revealed that the fixed cutter interval of the disc knife, arranged in an oriented manner, presents challenges due to the variations in the size and shape of seed potatoes [18,19]. This traditional form of cutting often results in inconsistent cuts, with some potatoes being sliced into thin pieces, thus limiting the suitability of existing machinery for efficient seed potato cutting [20,21]. Additionally, the distribution pattern of potato bud eyes is not sufficiently taken into account, and the inability to adjust the posture of seed potatoes during the conveying process contributes to a high blind eye rate in the seed potato pieces. This issue limits the suitability of existing machinery for seed potato cutting.

To overcome these limitations, this study explores the distribution pattern of bud eyes on the surface of seed potatoes. A novel seed potato cutting machine has been designed, which incorporates improvements in the posture adjustment mechanisms during transportation and optimized cutting mechanisms. This design adapts to different shapes and sizes of potatoes, thereby enhancing the quality of the cut seed potato pieces and reducing the blind eye rate. Through this innovative approach, this study addresses the central cutting issues associated with traditional machinery, offering a tailored solution that caters to the diverse characteristics of seed potatoes.

2. Materials and Methods

2.1. Distribution Pattern of Seed Potato Bud Eyes

The distribution pattern of bud eyes on the surface of seed potatoes is a critical factor influencing the qualification rate of seed potato cutting machines [22]. To investigate this distribution pattern, this study randomly selected 1000 seed potatoes of the local Forret variety from Inner Mongolia. Based on the agronomic requirements, the seed potatoes were categorized into three groups according to their long-axis size: small (50–70 mm), medium (70–90 mm), and large (90–110 mm). Their sizes are shown in

Table 1. Measurement results of physical parameters of potatoes.

Potato Varieties
Parameters	Length (mm)	Width (mm)	Height (mm)	Mass (g)
Range of measurement results	50–110	35–66	34–66	76–320
Average	72	50	46	195

. The distribution pattern of bud eyes was systematically observed, as illustrated in Figure 1. Through the observation of seed potato samples, it was found that small-sized seed potatoes exhibited an approximately ellipsoidal shape, with bud eyes sparsely distributed across the central surface area and primarily concentrated on the upper and lower sides as well as the endpoints. Medium-sized seed tubers predominantly assumed a cylindrical shape, with bud eyes randomly distributed across the surface, but with relatively fewer in the central region. The distribution of bud eyes on large-sized seed potatoes was similar to that of medium-sized potatoes. A statistical analysis of 1000 randomly selected seed potato samples revealed that 123 potatoes contained 1 to 2 bud eyes in the central region. Therefore, selecting the central region of the seed potato for cutting can effectively minimize the risk of bud eye removal. It was found that when the cutting knife was positioned at the center of the potato, each seed potato could be ensured to contain 1–2 bud eyes, as illustrated in Figure 1.

2.2. Structure and Working Principle of the Machine

The overall structure of the seed potato cutting machine is illustrated in Figure 2. It primarily consists of a first-level roller posture adjustment mechanism, a second-level baffle conveying mechanism, a cutting mechanism, a spraying mechanism, and a collection device. During operation, two speed motors drive the rotation of the first-level roller posture adjustment mechanism and the second-level baffle conveying mechanism. Specifically, the rollers in the first-level adjustment mechanism are hinged on a chain mounted on one side. As the chain rotates, the rollers also turn, allowing for the dynamic adjustment of the seed potatoes’ orientations. Under the combined action of gravity and friction, the seed potatoes move forward with the rotating edge of the conical rollers. The long-axis direction of the seed potatoes is adjusted to a vertical orientation as they are transported to the secondary baffle conveying mechanism, where they move steadily toward the cutting mechanism. As the seed potatoes pass through the cutting mechanism, they are cut into tuber pieces. Simultaneously, the spraying mechanism disinfects both the cutting blades and the tuber pieces. Finally, the processed tuber pieces are collected and bagged for further use.

2.3. Design of Key Components

2.3.1. Structural Design of the Cone Table Roller

The cone table roller is the core component of the primary roller posture adjustment mechanism, responsible for adjusting the conveying posture of the seed potatoes. Based on the structural dimensions of the seed potatoes, the cone table roller is designed as shown in Figure 3. The two rollers are arranged in a mirrored configuration. Preliminary tests determine that when D₁ = 90 mm, L₁ = 155 mm, L₂ = 105 mm, D₂ = 20 mm, and α = 7°, the center distance between two adjacent cone rollers is 100 mm. During the conveying process, the posture of the seed potatoes is continuously adjusted until the long-axis direction of the seed potatoes is perpendicular to the conveying direction. The cone table roller is made of nylon rod, and its conical surface is embossed to increase the friction between the seed potatoes and the roller surface.

2.3.2. Cutter Design and Parameterization

The cutter, being a pivotal component in the potato cutting process, plays a decisive role in determining both the quality of the cut and the operational efficiency. Empirical tests measuring the shear force required for seed potatoes reveal a positive correlation between the shear force and the contact area of the potato. It is observed that an excessively large cutter increases the contact area during the cutting process, thereby augmenting resistance. To ensure the cutter’s strength and wear resistance while minimizing cutting resistance, it is imperative to reduce the cutter’s length as much as feasible, along with minimizing its thickness and surface roughness. Consequently, 65 Mn hardened steel is selected to manufacture the cutter. Furthermore, considering the dimensions of the seed potatoes, the cutter is categorized into three distinct types: ’straight-shaped’ (with a cutting edge length of 90 mm, width of 60 mm, and thickness of 1.5 mm), ’Y-shaped’ (featuring a cutting edge length of 60 mm, width of 50 mm, thickness of 1.5 mm, and angle of 120°), and ’cross-shaped’ (with a cutting edge length of 110 mm, longitudinal edge length of 90 mm, width of 50 mm, and thickness of 1.5 mm), as illustrated in Figure 4. As the seed potatoes pass through the cutting mechanism, they are cut into 2 to 4 tuber pieces, depending on the configuration of the cutting blade. Specifically, a straight blade cuts a potato into 2 pieces, a Y-shaped blade into 3 pieces, and a cross-shaped blade into 4 pieces. All three types of cutters are capable of processing potatoes of varying sizes. In this study, the seed potatoes input into the machine to be cut range from 55 to 320 g (potatoes weighing less than 55 g can be directly planted as seed tubers, while those exceeding 320 g are relatively uncommon). To analyze the cutting performance of the three cutter configurations, only a single cutter type is operational at any given time, with the potatoes being randomly selected for each cutting trial.

2.4. Mechanical Analysis and Simulation of the Posture Adjustment Process

2.4.1. Mechanical Analysis of the Seed Potato Posture Adjustment Process

The posture adjustment of seed potatoes is a critical step in the seed potato cutting process. To ensure the successful adjustment of seed potato posture, it is essential to analyze the mechanical properties of the adjustment process. The seed potato is assumed to be an ellipsoidal rigid body with a uniform mass distribution, and the transportation process is considered to be free from external interference. The external force is assumed to act on the centroid of the potato [23,24,25]. The plane rectangular coordinate system is established with the potato centroid as the coordinate origin o, the horizontal right as the positive direction of the x-axis, and the vertical upward as the positive direction of the y-axis, as shown in Figure 5.

In accordance with D’Alembert’s principle, the equilibrium equation is expressed as Equation (1):

$$\left\{\begin{array}{l}\sum F_{\mathrm{x}}=F_1\sin \alpha +N_2\cos \beta -F_2\sin \beta -N_1\cos \alpha =0\\ \sum F_{\mathrm{y}}=G-F_1\cos \alpha -F_2\cos \beta -N_1\sin \alpha -N_2\sin \beta =0\\ G=mg\\ F_1=N_1\mathrm{f}\\ F_2=N_2\mathrm{f}\end{array}\right.$$

(1)

G is the gravity of the seed potato itself, N; F₁ and F₂ are the friction between the seed potato and the conical table roller, N; N₁ and N₂ are the support force of the seed potato by the two conical table rollers, N; α is the angle between the friction force F₁ and the positive direction of the y-axis, °; and β is the angle between the friction force F₂ and the positive direction of the y-axis, °.

Equation (1) describes the mechanical balance acting on the seed potato, where F₁ and F₂ represent the frictional forces between the seed potato and each roller, reflecting the frictional characteristics at the contact surfaces. N₁ and N₂ are the normal forces perpendicular to the contact surface; these forces collectively work to overcome the downward force caused by gravity G by maintaining the stability of the seed potato between the rollers.

If the seed potato is capable of rotating between the two conical table rollers, it will neither move in the positive direction nor the negative direction of the x-axis. Consequently, the following condition must be satisfied:

$$\left\{\begin{array}{l}\sum M_{O1}=F_{2}a\sin [90°-(\alpha +\beta )]+N_{2}a\cos [90°-(\alpha +\beta )]\\ -Ga\cos \alpha \ge 0\\ \sum M_{O2}=F_{1}b\sin [90°-(\alpha +\beta )]+N_{1}b\cos [90°-(\alpha +\beta )]\\ -Gb\sin \alpha \le 0\end{array}\right.$$

(2)

a is the distance from the center of mass of the potato o to the contact point o₁, mm; b is the distance from the center of mass of the potato o to the contact point o₂, mm; m is the mass of the seed potato, kg; and f is the coefficient of friction between the roller and seed potato.

Equation (2) considers the dynamic conditions of the seed potato during rotation, specifically describing the conical angles of the rollers through angles a and β, which directly affect the direction and magnitude of the forces at the contact points. Optimizing these angles can reduce cutting errors due to the irregular shapes of seed potatoes, improving the uniformity and efficiency of cutting.

By simplifying Formula (2), the resulting expression is given as Equation (3):

$$\left\{\begin{array}{l}{N}_1\le {\displaystyle \frac{mg\cos \alpha }{f\cos (\alpha +\beta )+\sin (\alpha +\beta )}}\\ N_2\ge {\displaystyle \frac{mg\cos \beta }{f\cos (\alpha +\beta )+\sin (\alpha +\beta )}}\end{array}\right.$$

(3)

From Equation (3), it is evident that the posture adjustment effect on the seed potato is influenced by factors such as the mass of the seed potato, its shape, and the coefficient of friction between the seed potato and the material. When the friction between the material and the seed potato is greater, the posture adjustment effect becomes more pronounced.

2.4.2. Mechanical Analysis of the Seed Potato Conveying Process

During the movement of the seed potato with the conical roller, if the rotational speed of the conical roller is excessively high, the seed potato may bounce during the conveying process and be propelled toward the secondary baffle conveying mechanism. This can disrupt the posture of the seed potato and adversely affect the potato cutting process. To ensure the smooth operation of the conveying mechanism, it is essential to analyze the rotational speed of the conical roller. A rectangular coordinate system is established with the center of mass of the seed potato and the axis of rotation of the conical roller as the y-axis, and a 90° counterclockwise rotation from this axis as the x-axis, as illustrated in Figure 6.

To prevent the seed potato from being thrown upward during the conveying process, it is necessary to ensure that the resultant force in the y-axis direction is greater than or equal to zero. Therefore, the following condition must be satisfied:

$$\sum F_{\mathrm{y}}=F_4\cos \beta -F_3\sin \alpha -N_3\cos \alpha -N_4\sin \beta +mg\cos \alpha -F_5\ge 0$$

(4)

N₃ and N₄ are the supporting force of conical roller to the seed potato, N; F₃ and F₄ are the friction between the seed potato and the roller, N; F₅ is the centrifugal force in the process of seed potato movement, N; β is the angle between F₄ and the positive direction of the Y-axis, °; and α is the angle between the support force N₃ and the negative direction of the Y-axis, °.

Where

$$\left\{\begin{array}{l}{F}_5=m{\omega }^{2}R\\ G=mg\\ F_3=N_3\mathrm{f}\\ F_4=N_4\mathrm{f}\end{array}\right.$$

(5)

ω₂ is the angular velocity of the cone roller around the shaft, r/min; and R is the distance from the center of mass o to the center of rotation o₅, mm.

By combining Equations (4) and (5), the following expressions are derived:

$$m{\omega }^{2}D\le N_4(f\cos \beta -\sin \beta )-N_3(\cos \alpha +f\sin \alpha )+mg\cos \alpha$$

(6)

Simplifying these equations yields the maximum angular velocity of rotation required to ensure that the seed potato is not thrown during the conveying process, as given by:

$$\omega \le \sqrt{{\displaystyle \frac{m\mathrm{g}\cos \beta +N_4(f\cdot \cos \beta -\sin \beta )-N_3(\cos \alpha +f\cdot \sin \alpha )}{mR}}}$$

(7)

From Equation (7), it is evident that the maximum rotational speed has an upper limit; exceeding this limit will cause the seed potato to be thrown upward during the conveying process, thereby negatively impacting the posture adjustment effect. In this analysis, the static friction coefficient between the seed potato and the nylon roller is approximately 0.6. The mass of the seed potato is 100 g, and the measured average short-axis dimension of the seed potato ranges from 40 to 55 mm. The distance from the center of the roller to the center of the axle is 150 mm, and the diameter of the conical table roller is 90 mm. Additionally, the rotation of the seed potato between the conical rollers must be considered. Based on these parameters, it is determined that the rotational speed of the conical roller should not exceed 25 revolutions per minute (r/min).

2.5. Experimental Design

2.5.1. Simulation of Seed Potato Posture Adjustment

The discrete element simulation software EDEM2019.1 was employed to further analyze the working process of seed potato conveyance and posture adjustment. The seed potatoes were categorized into three types—small, medium, and large—based on their long-axis dimensions. The shape contours of the seed potatoes were obtained using a 3D scanner, and the discrete element simulation model of the potato was established by filling the scanned contours with 3 mm spherical particles [26], as illustrated in Figure 7.

The physical parameters and contact parameters between the seed potato and the roller were determined through measurement and by referencing the relevant literature, as summarized in

Table 2. Parameters in DEM simulation.

Parameter	Value
Poisson’s ratio of seed potato	0.46
Poisson’s ratio of nylon rod	0.28
Density of seed potato/(kg/m3)	1088
Density of nylon rod/(kg/m3)	1150
Shear modulus of seed potato/(Pa)	1.12 × 106
Shear modulus of nylon rod/(Pa)	1.01 × 107
Restitution coefficient of seed potato–nylon rod collision	0.53
Dynamic friction coefficient of seed potato–nylon rod	0.05
Static friction coefficient of seed potato–nylon rod	0.62

. The rotational speed of the conical table roller was set to 20 r/min, while the size parameters of the conical table remained unchanged. Simulations were conducted with the taper angles of the conical table roller bevel set to 4°, 7°, 10°, and 13°, to observe the time required for the seed potatoes to achieve posture adjustment on the conical table roller. The posture adjustment process is illustrated in Figure 8.

2.5.2. Simulation of Seed Potato Dropping

The process by which seed potatoes fall from the primary posture-adjusting conveyor mechanism into the secondary baffle conveyor mechanism is of critical importance, as it significantly impacts the subsequent tuber cutting process. Maintaining the posture of the potato seed tubers to be consistent with their adjusted posture after falling into the secondary baffle mechanism can substantially enhance the qualified rate of potato cutting. Therefore, SolidWorks2013 was utilized to model the conical roller and the secondary baffle conveyor mechanism. To improve simulation efficiency, the model was simplified during the modeling process and subsequently imported into the EDEM software. The simulation model employed the Hertz–Mindlin (no slip) contact model, with various physical and contact parameters configured according to Table 1. In the simulation, the Rayleigh Time Step was fixed at 20%, the simulation time was set to 6 s, the cell size was set to 3.0R min, and the particle generation method was dynamic random generation.

In the simulation, the transport speed of the seed potato was used as the variable, while the length and taper of the conical roller were kept constant. The potato seed tubers were generated in a fixed posture, and three trials were conducted for the small, medium, and large seed potatoes. The objective was to observe whether the seed potatoes maintained their posture after falling into the secondary baffle conveyor mechanism.

2.5.3. Bench Test

The experiment was conducted at the potato mechanization test base in Ordos City. Xisen No. 6 and Furuite seed potatoes were selected as the test varieties. The average moisture content of the seed potatoes was 77.51%, and the mass of the potatoes ranged from 55 to 320 g. The test was performed using a seed potato cutting machine, and the experimental setup is shown in Figure 9.

Currently, the national industry standards have not established specific regulations regarding the cutting performance of seed potato cutting machines. In this experiment, the qualified rate of potato cutting and the blind eye rate of potato cubes were selected as evaluation metrics, based on the relevant literature and agronomic requirements.

The formula for calculating the qualified rate of potato cutting is as follows:

$$J_1={\displaystyle \frac{Q}{P}}\times 100\%$$

(8)

where J₁ represents the qualified rate of potato cutting; Q denotes the number of nuggets with a mass within the range of 35–85 g; and P corresponds to the total number of cut seed potato nuggets.

The formula for calculating the blind eye rate of potato tubers is as follows:

$$J_2={\displaystyle \frac{W}{P}}\times 100\%$$

(9)

In the formula, J₂ represents the blind eye rate of potato tubers; and W denotes the number of seed tubers lacking bud eyes on the surface of the cut tubers.

3. Results and Discussion

3.1. Simulation Results of Seed Potato Posture Adjustment

The simulation results are presented in Figure 10. When the bevel taper of the conical roller is 4°, the taper is insufficient, preventing the seed potato from aligning with the central axis of the symmetrical roller during rotation, and thus failing to achieve proper positioning. At a bevel taper of 7°, the posture adjustment time for all types of seed potatoes is shorter, and the performance is more effective. When the bevel taper is increased to 10°, although all types of seed potatoes can complete their positioning and posture adjustment operations, the time required is excessively long. At a bevel taper of 13°, the gap between adjacent rollers becomes too large, causing small- and medium-sized seed potatoes to fall into the gap during rotation, which prevents successful posture adjustment. Therefore, a bevel taper of 7° is selected for the conical roller in the design, as it yields optimal experimental results.

There is little research in the literature on the posture adjustment of seed potatoes in cutting machines. Liu employed a conical roller as the conveying and posture adjusting device in their potato cutting machine [27]. By configuring the structural parameters of the conical roller, using D₁ = 124 mm, D₂ = 20 mm, L₁ = 30 mm, L₂ = 30 mm, and α = 12° (refer to Figure 3), they achieved the transportation and posture adjustment of potatoes weighing between 100 and 300 g. However, the study only qualitatively described the ability of the conical roller to adjust the posture of potatoes during transmission, without conducting any related simulation analysis.

Zhu developed a potato seed cutting machine that utilized a coordinated operation of longitudinal disc cutter sets and transverse cutter sets [28]. This machine employed conical rubber rollers to adjust the orientation of potatoes, which were then fed into the longitudinal disc cutter in a fixed orientation. After the initial longitudinal cutting, oversized potato pieces were directed by a deflector plate to the transverse cutter for secondary cutting. However, the indeterminate positioning of seed potatoes on the conical rubber rollers resulted in random orientations when entering the disc cutter, leading to irregular sizes and shapes of the cut seed potatoes. This randomness often caused the densely budded tops of the seed potatoes to be sliced, resulting in significant seed loss.

3.2. Simulation Results of Seed Potato Dropping

The simulation process of seed potato dropping is illustrated in Figure 11. The simulation results indicate that when the rotation speed ratio between the roller and the baffle is maintained at 5:8, the secondary baffle conveyor mechanism can smoothly receive the potato seed tubers. Specifically, when the rotating speed of the cone table roller is set to 20 r/min and the baffle’s rotating speed is set to 36 r/min, no bouncing or throwing phenomena of the seed potatoes are observed. However, when the rotating speed of the cone table roller exceeds 25 r/min, the initial velocity of the seed potatoes falling into the secondary baffle becomes too high, causing the potatoes to rebound and altering their posture. This prevents the potatoes from landing in the correct position, significantly affecting the qualified rate of potato cutting and the blind eye rate in the tuber pieces.

From the simulation of the seed potato conveying and posture adjustment process, it is evident that when the speed ratio is 5:8 and the rotating speed of cone table roller does not exceed 25 r/min, the initial positions of the roller and the baffle can be determined, to ensure that all three types of seed potatoes (small, medium, and large) fall smoothly into the secondary baffle mechanism without any change in posture.

3.3. Bench Test Results

To achieve the objectives of a high qualified rate of potato cutting and a low blind eye rate in the potato pieces, preliminary single-factor experiments were conducted. These experiments analyzed the influence of the conical roller speed, the number of cone rollers, and the cutting angle of the cutter on the qualified rate of potato cutting and the blind eye rate. The results indicated that within the ranges of 10–16 rpm for the conical roller speed, 36–44 for the number of cone rollers, and 0–10° for the cutting angle of the cutter, the qualified rate of potato cutting was higher, and the blind eye rate was lower.

In accordance with an L₉(3⁴) orthogonal table, a three-factor, three-level, orthogonal test was designed. Orthogonal tests were conducted using three types of cutters: straight-shaped, Y-shaped, and cross-shaped. The factors and levels for the orthogonal tests of the cutting performance of the seed potato cutting machine are presented in

Table 3. Factors and levels for the orthogonal tests of the performance of the seed potato cutting machine.

Level		Influencing Factor
		A Rotating Speed of Cone Table Roller (r/min)	B Number of Cone Table Rollers	C Cutting Angle of Cutter (°)
straight-shaped cutter	1	10	36	0
	2	12	40	5
	3	14	44	10
Y-shaped cutter	1	10	36	0
	2	12	40	5
	3	14	44	10
cross-shaped cutter	1	12	36	0
	2	14	40	5
	3	16	44	10

. The test results for the cutting performance of the three types of cutters are summarized in

Table 4. Results of the cutting performance tests.

Order	Test Level Value				Qualified Rate of Potato Cutting/%			Blind Rate of Potato Tubers/%
	A	B	C	Error	Straight-Shaped	Y-Shaped	Cross-Shaped	Straight-Shaped	Y-Shaped	Cross-Shaped
1	1	1	1	1	79.1	76.2	80.7	5.8	5.1	4.3
2	1	2	2	2	82.9	81.8	82.5	3.5	3.2	3.2
3	1	3	3	3	82.5	78.9	81.2	3.5	4.3	5.2
4	2	1	2	3	80.5	76.6	79.3	5.3	5.3	3.4
5	2	2	3	1	79.3	74.8	76.5	4.7	6.5	4.5
6	2	3	1	2	89.1	86.4	89.6	1.3	2.6	1.4
7	3	1	3	2	70.6	73.7	74.3	9.5	7.6	7.1
8	3	2	1	3	80.1	85.3	84.3	4.2	2.8	2.3
9	3	3	2	1	84.6	89.6	85.2	2.8	1.8	2.5

, while Figure 12 illustrates the potato tubers cut by the different cutter types.

As shown in

Table 5. Analysis of variance (ANOVA) and range analysis.

Indexes	Type	Straight-Shaped			Y-Shaped			Cross-Shaped
	Analysis Item	A	B	C	A	B	C	A	B	C
Qualified rate of potato cutting (%)	K1	244.5	230.2	248.3	236.9	226.5	247.9	246	234.9	255.2
	K2	248.9	242.3	248	237.8	241.9	248	248.4	247.3	246
	K3	235.3	256.2	232.4	248.6	254.9	227.4	241.8	254	235
	R	4.6	8.7	5.3	3.9	9.5	6.9	2.2	6.4	6.8
	mean square	16.1	56.4	27.6	14.1	67.4	46.9	3.7	31.3	34.1
	value F	688	2418	1181	86.5	412.5	287.3	3.5	29.7	32.4
	value p	0.0014 *	0.0004 **	0.0008 **	0.0114 *	0.0024 **	0.0034 **	0.2206	0.0325 *	0.0299 *
	prioritized factors	B > C > A			B > C > A			C > B > A
	optimal composition	B3C1A2			B3C2A3			C1B3A2
The blind eye rate of potato tubers (%)	K1	12.8	20.6	11.3	12.6	18.0	10.5	12.7	14.8	8.0
	K2	11.3	12.4	11.6	14.4	12.5	10.3	9.3	10.0	9.1
	K3	16.5	7.6	17.7	12.2	8.7	18.4	11.9	9.1	16.8
	R	1.7	4.3	1.8	0.7	3.1	2.7	1.1	1.9	2.9
	mean square	2.4	14.4	4.3	0.5	7.3	7.1	1.1	3.1	7.7
	value F	15.5	93.3	28.2	4.1	65.6	64	19.7	58.7	143.7
	value p	0.0607 *	0.0106 *	0.0343 *	0.1953	0.0150 *	0.0153 *	0.0481 *	0.0167 *	0.0069 **
	prioritized factors	B > C > A			B > C > A			C > B > A
	optimal composition	B3C1A2			B3C2A3			C1B3A2

“*” represents the degree of significance, and “**” represents a more significant degree.

, there is a significant relationship between the three factors (number of conical rollers, cutting angle, and rotational speed) and the two performance indicators (qualified rate of potato cutting and blind eye rate of potato tubers) in the straight-shaped cutter test. The optimal working combination for maximizing the qualified rate and minimizing the blind eye rate is B₃C₁A₂, which corresponds to 44 conical rollers, a cutting angle of 0°, and a rotational speed of 12 r/min. Under these conditions, the qualified rate of potato cutting reaches 89.1%, and the blind eye rate of the potato tubers is 1.3%. Similarly, in the Y-shaped cutter test, a significant relationship exists between the three factors and the two performance indicators. The optimal working combination is B₃C₂A₃, which includes 44 conical rollers, a cutting angle of 5°, and a rotational speed of 14 r/min. This configuration achieves a qualified rate of 89.6% and a blind eye rate of 1.8%. For the cross-shaped cutter test, the number of conical rollers and the cutting angle significantly affect the qualified rate of potato cutting, while the rotational speed of the conical rollers has no significant impact. However, the rotational speed exhibits a highly significant effect on the blind eye rate. The optimal working combination for this cutter type is C₁B₃A₂, which consists of a cutting angle of 0°, 44 conical rollers, and a rotational speed of 14 r/min. This setup yields a qualified rate of 89.6% and a blind eye rate of 1.4%.

Wang et al. developed a combined positioning and cutting device for segmenting potato seed tubers, utilizing the qualified cutting rate and blind eye rate as evaluation metrics. The experiment was designed as a three-factor, three-level response surface test, with the central distance of the conical roller set, the chain conveyor speed, and a V-shaped blade angle as the experimental factors [29]. The experimental results were analyzed using the Design-Expert 12.0.3 software for variance analysis and the interaction effects. The qualified cutting rate ranged from 87.52% to 98.35%, while the blind eye rate ranged from 1.17% to 3.08% under various factor combinations. The variance analysis revealed that the factors influencing the qualified cutting rate, in descending order of significance, were the V-shaped blade angle, the chain conveyor speed, and the central distance of the conical roller set. For the blind eye rate, the order of significance was the central distance of the conical roller set, the V-shaped blade angle, and the chain conveyor speed. The software optimization module identified the optimal parameter combination as a central distance of 100.83 mm for the conical roller set, a chain conveyor speed of 0.019 m/s, and a V-shaped blade angle of 49.50°.

In a separate study, Wang et al. designed and constructed a directional alignment and cross-cutting machine for potato seed tubers [17]. The experiment employed the intermediate motor speed, the central distance between the upper and lower rubber rollers, and the installation angle of the potato cutting comb as experimental factors, with the qualified tuber rate, blind eye rate, and seed tuber loss rate as evaluation metrics. A multi-factor response surface experiment revealed that the central distance between the upper and lower rubber rollers had a significant impact on the qualified tuber rate and blind eye rate, with the order of influence being the central distance, intermediate motor speed, and installation angle of the potato cutting comb. The intermediate motor speed significantly affected the seed tuber loss rate, with the order of influence being the intermediate motor speed, installation angle of the potato cutting comb, and central distance between the upper and lower rubber rollers. Using the Design-Expert 8.0.6 software to analyze the experimental data, the qualified cutting rate ranged from 71.23% to 95.25%, the blind eye rate ranged from 1.37% to 5.89%, and the seed tuber loss rate ranged from 9.25% to 15.02% under various factor combinations.

3.4. Verification Test

Based on the results of the orthogonal test, the optimal operating parameters for each type of cutter were determined, as presented in

Table 6. Optimal parameter combinations.

Optimal Composition	The Rotation Speed of The Cone Roller (r/min)	The Number of Cone Rollers	The Cutting Angle of The Cutter (°)
Straight-shaped cutter B3C1A2	12	44	0
Y-shaped cutter B3C2A3	14	44	5
Cross-shaped cutter C1B3A2	14	44	0

.

Under the optimal operating parameters, the performance of the seed potato cutting machine was validated. The results are presented in

Table 7. Verification test results of the optimal parameter combinations.

Test Indexes		Order Number			Average Value	Standard
		1	2	3
Straight-shaped cutter	Qualified rate of potato cutting (%)	91.3	89.6	90.0	90.3	≥80
	The blind eye rate of the potato tubers (%)	1.5	1.8	2.3	1.86	≤4
Y-shaped cutter	Qualified rate of potato cutting (%)	88.3	86.4	89.2	87.9	≥80
	The blind eye rate of the potato tubers (%)	2.8	3.5	2.3	2.86	≤4
Cross-shaped cutter	Qualified rate of potato cutting (%)	86.3	88.6	86.5	87.1	≥80
	The blind eye rate of the potato tubers (%)	3.5	3.4	4.5	3.80	≤4

. For the straight-shaped cutter, the qualified rate of potato cutting was 90.3% and the blind eye rate of the potato tubers was 1.86%. For the Y-shaped cutter, the qualified rate of potato cutting was 87.9% and the blind eye rate of the potato tubers was 2.86%. For the cross-shaped cutter, the qualified rate of potato cutting was 87.1% and the blind eye rate of the potato tubers was 3.80%. These results meet the agronomic requirements for seed potato processing.

Wang et al. conducted a series of experiments on the segmented cutting of potato seed tubers using a combined positioning and cutting mechanism. Based on variance analysis, the experimental validation demonstrated that when the central distance of the conical roller set was 101.60 mm, the chain conveyor speed was 0.019 m/s, and the V-shaped blade angle was 49.50°, the qualified cutting rate reached 90.56%, with a blind eye rate of 1.27%. The relative error compared to the optimized values was less than 5% [29].

In another study, Wang et al. performed experiments on a directional alignment and cross-cutting machine for potato seed tubers. The results indicated that under the optimal parameter combination, where the intermediate motor speed was 965.76 r/min, the central distance between the upper and lower rubber rollers was 315 mm, and the installation angle of the potato-cutting comb was 104.61°, the qualified tuber rate was 92.13%, the blind eye rate was 1.91%, and the seed tuber loss rate was 10.21%. Compared to the predicted values, the relative errors for the qualified tuber rate, blind eye rate, and seed tuber loss rate were 2.88%, 3.80%, and 5.04%, respectively [17].

4. Conclusions

(1)

A seed potato cutting machine was designed and fabricated, with key components such as the conical roller wheels, cutting blades, baffle plates, and collection devices being optimized. This machine was capable of adjusting the orientation of seed tubers and performing functions such as cutting, spraying, and collecting potato tubers.

(2)

The working process of the conical roller wheel orientation adjustment mechanism was simulated and analyzed using EDEM software to identify the critical factors affecting the orientation adjustment of potato seed tubers. When the bevel taper of the conical roller was 7°, the posture adjustment time was minimized, and the adjustment effectiveness was maximized. Additionally, the rotational speeds of the primary orientation adjustment conveyor mechanism and the secondary baffle conveyor mechanism were set at 20 r/min and 36 r/min, respectively, to ensure the smooth passage of seed tubers.

(3)

Using the rotational speed of the conical rollers, the number of conical rollers, and the cutting angle of the cutter as experimental factors, and the qualified rate of potato cutting and the blind eye rate of the potato tubers as evaluation indexes, an orthogonal test was conducted to evaluate the performance of different cutters. Through range analysis and variance analysis of the test results, the optimal parameter combinations for each cutter type were determined. For the straight-shaped cutter, the optimal combination was a conical roller speed of 12 r/min, 44 conical rollers, and a cutting angle of 0°. Under these conditions, the qualified rate of potato cutting reached 90.3%, and the blind eye rate of the potato tubers was 1.86%. For the Y-shaped cutter, the optimal combination was a conical roller speed of 14 r/min, 44 conical rollers, and a cutting angle of 5°. This configuration resulted in a qualified rate of 87.9% and a blind eye rate of 2.86%. For the cross-shaped cutter, the optimal combination was a conical roller speed of 14 r/min, 44 conical rollers, and a cutting angle of 0°. Under these parameters, the qualified rate of potato cutting was 87.1%, and the blind eye rate of the potato tubers was 3.80%.