# Design of Cotton Recovery Device and Operation Parameters Optimization

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

^{6}hm

^{2}, and the yield reached 5 × 10

^{6}tons. Approximately 1.5 × 10

^{5}tons of cotton are left in the cotton field after a 3% loss, and the amount of cotton that has fallen is ample. Consequently, one of the challenges of cotton resource exploitation is the effective recovery of cotton distributed over the ground.

## 2. Materials and Methods

#### 2.1. Structure and Operating Principle of the Cotton Recovery Device

#### 2.2. Design and Analysis of the Major Components

#### 2.2.1. Design of the Sawtooth Roll-Tie-Type Cotton-Picking Mechanism

#### 2.2.2. Analysis of the Motion Characteristics of the Serrated Disc

_{1}to point F after time t, while the sawtooth tooth endpoint E

_{1}rotates to point E. If the angle through which the sawtooth tooth end rotates α(α = ωt), then the sawtooth tooth end E point’s equation of motion is:

_{1}are the center of rotation of the serrated disk at different moments.

_{x}, and the backward horizontal component speed ensures the effect of the saw teeth hooking the cotton. When ωRcos(ωt) + v = 0, we can obtain:

_{1}to the device’s forward velocity v be:

#### 2.2.3. Analysis of the Conditions of Flooring Cotton without Missing Pickup

_{2}. The serrations arrive at the initial point E of tying into the cotton; at this time, the initial phase angle between L

_{OE}and Y-axis is θ. The time elapsed from the movement of the serrated disk axis O to O

_{1}is t

_{1}, and the time elapsed from the movement to O

_{2}is t

_{2}. According to the analysis presented in Figure 4,

_{2}and E

_{1}coincide, the criterion for continual collection of cotton fallen to the ground is satisfied, and the critical condition can be attained as:

_{1}= 2α/ω. When the number of saw teeth on the serrated disc is set to z, the adjacent serrated angle can be obtained as θ = 2π/z. Subsequently, the next saw teeth turn the angle after the serrated tooth end is located at point E; the required time is t

_{3}= 2π/zω, where t

_{3}= t

_{2}− t

_{1}. Thus, t

_{1}, t

_{2}appear in Equation (8), and finishing can be obtained as:

_{1}is the time required for the serrated tooth end to move from E to E

_{2}(s); t

_{2}is the required time for adjacent serrated tooth ends to hook the cotton individually (s); t

_{3}is the time required for the latter serrated tooth end to move to point E until the previous serrated tooth leaves point E

_{2}(s); and α is the initial phase angle of the serrated tooth end from immediately hooking the cotton (°).

#### 2.3. Design of the Cotton Unloading Mechanism

^{2}); n

_{1}is the rotational speed of the serrated disk (rpm); R is the instantaneous rotation radius of the serrated disk (mm).

_{f}of the saw teeth on the cotton was measured to be approximately 2.2 times the cotton’s specific gravity, or F

_{f}= 2.2 mg. In addition, R = 300 mm was chosen as the rotational radius of the serrated disk. When cosθ = 0, the minimum rotation speed of the cotton out of the serrated disc was n

_{1}= 80.96 rpm. If the speed is poor, the picking efficiency will be low, and the operating requirements will not be reached. Under centrifugal force, cotton is easily dislodged from the sawtooth disk if the speed is extremely high. Combining theoretical analysis with the actual operation, the initial serrated disk speed was set as 60 rpm. According to [22], the brush roll surface’s linear speed is typically 1.5–2 times that of the serrated tooth end. The spinning radius of the brush roller is 85 mm, and its computed speed range is 317.64~423.53 rpm. In conjunction with the preliminary test, the final brush roller speed determination is 400 rpm. Since the speed of the serrated disc cannot exceed 80.96 rpm, the speed ratio of the serrated disc to the brush roll exceeds 1:5, and the brush roll will brush over the serrated teeth many times without missing the cotton.

#### 2.4. Discrete Element Modeling of the Motion Process of the Cotton-Picking Mechanism

#### 2.4.1. Modeling and Parameter Setting of the Simulation Model

^{−6}, the simulation time is set to 2 s, and the grid cell size is three times the minimum soil particle size. The contact models were selected from soil–soil and soil–cotton-picking mechanisms. The main parameters included contact parameters (soil recovery coefficient, static friction coefficient, and dynamic friction coefficient) and intrinsic parameters (density, Poisson’s ratio, and shear modulus). The data of the main parameters of the discrete element method test model were obtained by the method of calibration and optimization of the discrete element parameters of clay loam soil from the stacking test [23,24,25], and the relevant parameters are shown in Table 2.

#### 2.4.2. Analysis of Simulation Results

#### 2.5. Test Materials

#### 2.6. Test Methods

_{1}. After the machine operation, the mass of the missed cotton at the test points was manually recovered and cleaned up as M

_{2}, and the picking rate was calculated using Equation (13).

_{1}is the picking rate of cotton (%); η

_{2}is the impurities rate of cotton (%); M

_{1}is the total mass of cotton in the testing points (g); M

_{2}is the mass of cotton left in each testing point (g); M

_{d}is the mass of impurities, such as stalks, broken leaves, and boll shells picked out manually (g); M

_{c}is the mass of impurities separated from the sample using the test gin (g); M

_{x}is the mass of impurities separated from the lint in the sample using the cotton impurity separator (g); M

_{y}is the mass of the sample (g).

_{1}and the impurity rate η

_{2}. Figure 10 illustrates the single-factor test’s results. When the operating speed of the machine increased, the picking rate showed a trend of first increasing and then decreasing, and the overall impurity rate showed an increasing trend; when the spacing of the serrated disc increased, the picking rate showed a continuous decreasing trend, and the impurity rate first decreased and then increased; when the speed of the serrated disc increased, the picking rate first increased and then decreased, and the overall impurity rate showed an increasing trend.

#### 2.7. Test Results

## 3. Results and Discussion

_{1}and η

_{2}on X

_{1}, X

_{2}, and X

_{3}was tested.

- (1)
- Establishment of the regression equation and significance analysis of the picking rate

_{1}, X

_{3}, X

_{1}

^{2}, and X

_{3}

^{2}had an extremely significant impact on the picking rate model. X

_{2}and X

_{2 × 3}had a more significant impact on the picking rate model. The significance of the influence of each variable on the pickup rate was in the following order, from more to less significant: the serrated disc speed, the machine operation speed, and the spacing between serrated discs. After eliminating the insignificant factors, the quadratic regression equation of each variable on the picking rate was obtained [29], as shown in Equation (15):

- (2)
- Establishment of the regression equation and significance analysis of the impurity rate

_{2}, X

_{1 × 2}, and X

_{1}

^{2}had an extremely significant impact on the impurity rate model. X

_{1}had a significant impact on the impurity rate model. The significance of the influence of each variable on the impurity rate was in the following order, from more to less significant: the spacing between serrated discs, the machine operation speed, and the serrated disc speed. After eliminating the insignificant factors, the quadratic regression equation of each variable on the impurity rate was obtained as shown in Equation (16):

#### 3.1. Response Surface Analysis

- (1)
- Analysis of the influence of the picking rate

_{3}is fixed at 60 rpm and X

_{1}is increased, the picking rate increases, then decreases, and the rate of decline becomes more gradual. When X

_{2}increases, the picking rate increases gradually, with a moderate degree of change. Figure 12b shows that when X

_{2}is fixed at 50 mm, X

_{1}and X

_{3}are increased, and the picking rate of cotton fallen on the ground increases initially and then decreases. Figure 12c indicates that when X

_{1}controls 0.9 m/s, the pickup rate gradually grows as X

_{2}increases, with a relatively flat amplitude of change; when X

_{3}increases, the pickup rate gradually climbs and drops slowly.

- (2)
- Analysis of the influence of the impurity rate

_{3}is held constant at 60 rpm and X

_{1}increases, the impurity rate drops and then increases with a significant trend. In addition, the rate of impurity gradually increases as X

_{2}rises. Figure 12e demonstrates that when X

_{2}is fixed at 50 mm, and X

_{1}and X

_{3}increase, the impurity rate increases and subsequently declines. Figure 12f demonstrates that when X

_{1}is regulated to 0.9 m/s, the impurity rate grows gradually, with only minor variations. In addition, as X

_{3}grows, the impurity rate reduces gradually and then rises gradually, with changes that are likewise relatively slow.

#### 3.2. Parameter Optimization and Test Validation

## 4. Conclusions

- For cotton machine harvesting in Xinjiang, there was no suitable mechanism to recover cotton fallen on the ground. In this study, a sawtooth-type recovery device was designed to recover cotton fallen on the ground and efficiently unload it. The device consists of a sawtooth roll-tie-type cotton-picking mechanism, cotton unloading mechanism, cotton collection box, and other parts. The primary design parameters were determined using the analysis of the motion of the serrated discs, the cotton non-missing picking condition, and the cotton unloading condition.
- EDEM simulated the process of the cotton-picking mechanism movement. The maximum force on the tooth end of the serrated teeth was obtained during the working process. Then, ANSYS analysis of strain and stress on the tooth end of the serrated teeth was carried out to verify that the structural strength of the serrated disc meets the design requirements.
- Considering the machine operating speed, spacing between serrated discs, and serrated disc speed as the experimental factors, the picking and impurity rates of the cotton fallen on the ground were used as the test indicators. Additionally, the response surface data were analyzed using Design Expert software, and multiple fittings obtained the regression equation of the picking and impurity rates. The influence of the interaction of various factors on the picking and impurity rates was determined.
- Experimental tests on the device proved that when the optimized machine operating speed was 0.96 m/s, the spacing between serrated discs was 40 mm, and the speed of the serrated disc was 68 rpm. In addition, the picking and impurity rates of the cotton fallen on the ground were 79.09 and 35.12%, respectively. The optimized operating parameters were verified experimentally. Relative errors between the experimental results and optimized theoretical values of the picking and impurity rates were 2.37 and 3.79%, respectively, relatively small. Thus, the model was highly reliable.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**Cotton recovery device: 1. frame; 2. hydraulic device; 3. hangers; 4. hydraulic motor; 5. sprockets; 6. straw shield; 7. sawtooth roll-tie cotton-picking mechanism; 8. cotton collection box; and 9. cotton unloading mechanism. (

**a**) Structure diagram of the cotton recovery device. (

**b**) Schematic diagram of the principle of the cotton recovery device.

**Figure 2.**Sawtooth roll-tie-type cotton-picking mechanism: 1. straw shield; 2. ground wheel; 3. serrated disc; 4. guard ring.

**Figure 4.**Adjacent serrated tooth end motion trajectory. v is the operating speed of the machine (m/s); ω is the angular speed of the serrated disc, (rad·s

^{−1}); O, O

_{1}, and O

_{2}are the centers of rotation of the serrated disc at different moments; E is the initial point of the serrated tooth end into the cotton; E

_{1}is the deepest point of the serrated tooth end into the cotton; E

_{2}is the point of the serrated tooth end out of the cotton; E′ is the point of the adjacent serrated tooth end into the cotton; vt

_{1}is the displacement of the rotary center of the previous serrated tooth in time t

_{1}(mm); vt

_{2}is the displacement of the rotary center of the latter saw tooth in time t

_{2}(mm).

**Figure 6.**Force analysis of cotton. ω

_{1}and ω

_{2}are the rotational angular speed of the serrated disk and brush roller, respectively (rad/s); F

_{f}is the force of the serrated teeth on the cotton (N); F is the force of the brush roller on the cotton (N); θ is the angle between the force of the brush roller on the cotton and its own gravity (°); F

_{1}is the centrifugal force on the cotton (N); F

_{N}is the support force of the serrated teeth on the cotton (N); and G is the gravity of the cotton (N).

**Figure 7.**Particle and geometric simulation model. (

**a**) Particle model of the soil; (

**b**) simulation model of the EDEM.

**Figure 9.**Analysis results. (

**a**) Serrated disc tooth strain model; (

**b**) Serrated disc tooth stress model.

**Figure 10.**Single factor test. (

**a**) The effect of machine operation speed on the operating effect. (

**b**) The effect of spacing between serrated discs on the operating effect. (

**c**) The effect of the serrated disc speed on the operating effect.

**Figure 12.**Effects of the interaction of various factors on the picking rate and trash content of cotton fallen on the ground. (

**a**). η

_{1}= (X

_{1}, X

_{2}, 60); (

**b**). η

_{1}= (X

_{1}, 50, X

_{3}); (

**c**). η

_{1}= (0.9, X

_{2}, X

_{3}); (

**d**). η

_{2}= (X

_{1}, X

_{2}, 60); (

**e**). η

_{2}= (X

_{1}, 50, X

_{3}); (

**f**). η

_{2}= (0.9, X

_{2}, X

_{3}).

Parameter | Value |
---|---|

Structure form | Traction type |

Overall dimension (length × width × height)/mm | 1670 × 1240 × 1550 |

Engine rated power/kW | 51.5 |

Effective working width/mm | 1000 |

Picking rate/% | ≥75 |

Impurity rate/% | 40≤ |

Item | Parameter | Value |
---|---|---|

Soil particles | Poisson’s ratio | 0.30 |

Shear modulus/Pa | 5 × 107 | |

Density/(kg·m^{−3}) | 2600.00 | |

Cotton-picking mechanism | Poisson’s ratio | 0.30 |

Shear modulus/Pa | 7.90 × 1010 | |

Density/(kg·m^{−3}) | 7850.00 | |

Particle−Particles | Recovery coefficient | 0.21 |

Static friction coefficient | 0.68 | |

Dynamic friction coefficient | 0.27 | |

Particle−Cotton-picking mechanism | Recovery coefficient | 0.54 |

Static friction coefficient | 0.53 | |

Dynamic friction coefficient | 0.13 |

Coded Value | Machine Operation Speed X_{1} (m·s^{−1}) | Spacing between Serrated Discs X_{2} (mm) | Serrated Disc Speed X_{3} (rpm) |
---|---|---|---|

−1 | 0.6 | 40 | 40 |

0 | 0.9 | 50 | 60 |

1 | 1.2 | 60 | 80 |

Test | X_{1} | X_{2} | X_{3} | η_{1} | η_{2} |
---|---|---|---|---|---|

1 | 0 | 1 | 1 | 78.1 | 40.1 |

2 | 0 | 0 | 0 | 81.4 | 36.5 |

3 | −1 | 1 | 0 | 78.1 | 60.3 |

4 | −1 | 0 | −1 | 71.1 | 48.3 |

5 | 1 | 0 | −1 | 74.7 | 57.4 |

6 | 0 | 0 | 0 | 80.6 | 37.6 |

7 | 0 | 0 | 0 | 79.9 | 34.7 |

8 | 1 | −1 | 0 | 79.3 | 53.6 |

9 | 0 | 0 | 0 | 81.3 | 33.8 |

10 | 1 | 1 | 0 | 81.2 | 54.3 |

11 | −1 | −1 | 0 | 76.3 | 39.7 |

12 | 0 | 1 | −1 | 78.3 | 39.4 |

13 | 1 | 0 | 1 | 77.5 | 59.6 |

14 | 0 | 0 | 0 | 81.2 | 35.7 |

15 | 0 | −1 | −1 | 74.4 | 36.4 |

16 | 0 | −1 | 1 | 79.3 | 33.8 |

17 | −1 | 0 | 1 | 76.3 | 53.1 |

Source of Variation | DOF | Picking Rate η_{1}/% | Impurity Rate η_{2}/% | ||||
---|---|---|---|---|---|---|---|

Sum of Squares | F | Significant Level p | Sum of Squares | F | Significant Level p | ||

Models | 9 | 130.47 | 30.89 | <0.0001 ** | 1514.95 | 26.68 | 0.0001 ** |

X_{1} | 1 | 14.85 | 31.64 | 0.0008 ** | 69.03 | 10.94 | 0.0130 * |

X_{2} | 1 | 5.12 | 10.91 | 0.0131 * | 117.05 | 18.55 | 0.0035 ** |

X_{3} | 1 | 20.16 | 42.96 | 0.0003 ** | 3.25 | 0.5153 | 0.4961 |

X_{1 × 2} | 1 | 0.0025 | 0.0053 | 0.9439 | 99.00 | 15.69 | 0.0055 ** |

X_{1 × 3} | 1 | 1.44 | 3.07 | 0.1233 | 1.69 | 0.2679 | 0.6207 |

X_{2 × 3} | 1 | 6.50 | 13.85 | 0.0074 * | 2.72 | 0.4315 | 0.5322 |

X_{1}^{2} | 1 | 24.05 | 51.24 | 0.0002 ** | 1180.61 | 187.12 | <0.0001 ** |

X_{2}^{2} | 1 | 0.2325 | 0.4954 | 0.5043 | 0.7785 | 0.1234 | 0.7357 |

X_{3}^{2} | 1 | 54.27 | 115.62 | <0.0001 ** | 20.29 | 3.22 | 0.1160 |

Residual | 7 | 3.29 | 44.16 | ||||

Lack of fit | 3 | 1.70 | 1.43 | 0.3954 | 35.31 | 5.32 | 0.0701 |

Pure error | 4 | 1.59 | 8.85 | ||||

Total | 16 | 133.75 | 1559.12 |

Parameter | Picking Rate η_{1}/% | Impurity Rate η_{2}/% |
---|---|---|

Theoretical optimization value | 81.01 | 33.79 |

Test average | 79.09 | 35.12 |

Relative error | 2.37 | 3.79 |

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## Share and Cite

**MDPI and ACS Style**

Wang, H.; Cao, S.; Liu, Y.; Yang, Y.; Meng, X.; Ji, P.
Design of Cotton Recovery Device and Operation Parameters Optimization. *Agriculture* **2022**, *12*, 1296.
https://doi.org/10.3390/agriculture12091296

**AMA Style**

Wang H, Cao S, Liu Y, Yang Y, Meng X, Ji P.
Design of Cotton Recovery Device and Operation Parameters Optimization. *Agriculture*. 2022; 12(9):1296.
https://doi.org/10.3390/agriculture12091296

**Chicago/Turabian Style**

Wang, Hezheng, Silin Cao, Yongrui Liu, Yuxin Yang, Xiangyu Meng, and Peng Ji.
2022. "Design of Cotton Recovery Device and Operation Parameters Optimization" *Agriculture* 12, no. 9: 1296.
https://doi.org/10.3390/agriculture12091296