# Design and Operating Parameters Optimization of the Hook-and-Tooth Chain Rail Type Residual Film Picking Device

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Structure and Working Principle of Residual Film Recycling Machine

#### 2.1.1. The Main Components and Working Principle of The Picking Device

#### 2.1.2. Hook Tooth Assembly

_{a}is the effective length of the deflection chute, (mm); R

_{a}is the distance from the center of the hook tooth mounting shaft to the center of the short shaft, (mm); φ is the rotation angle of the hook tooth assembly, (°).

_{a}= 29 mm can be obtained from an equation based on the characteristics of the guiding hook tooth assembly (1). If the total number of guiding hook teeth designed to rotate in the de-filming area is greater than two, the total number of guiding hook teeth for variable rotation in the de-filming area is 2.5 groups, and the distance between two adjacent rake teeth installation axis of rotation is 190 mm, then the effective length of the directional slide is 475 mm.

#### 2.1.3. Pick-Up Film Hook Teeth

_{f}after a certain twist, the angle of the twist is φ

_{1}, and in order to ensure the efficiency of the residual film pick-up, at this time the hook tooth operation should meet the conditions of

_{1}is the angle of twist of the hook teeth into the soil (°); L is the distance from the center of rotation of the hook teeth to the tip of the teeth (mm); D is the diameter of the torsion spring (mm); n is the effective number of turns of the torsion spring; F

_{f}is the resistance of the hook teeth into the soil (N); P is the number of hook teeth per row.

_{1}is the distance between hook teeth in the same row (mm); S is the distance between wide rows of cotton stalks (mm); Z is the distance between narrow rows of cotton stalks (mm).

_{1}is 200 mm, and the number of hook teeth in each row P is 9.1 by substituting the above formula; then, 9 hook teeth or 9 half hook teeth are arranged on each of the hook tooth mounting shafts.

#### 2.1.4. Hook Tooth Arrangement

#### 2.2. Analysis of Picking Process of Hook-Tooth Chain Rail Film Picking Device

#### 2.2.1. Determination of Inclination Angle of Hook Teeth

_{OA}and the vertical direction is:

_{s}is the distance between rake axis and tooth tip, (mm); D is the chain rake driven shaft sprocket indexing circle diameter, (mm); E is the distance from the center of the crochet assembly to the center of the chain rake chain roller (mm); L

_{OA}is the distance from the center of chain rake driven shaft to the tip of hook tooth (mm).

_{OA}= 359 mm. The maximum embedded depth h of the hook tooth is 60 mm, and the embedded angle α of the hook tooth is 56.4°.

#### 2.2.2. Motion Analysis of Film-Picking Hook Teeth

_{OA}is the rotation radius of the hook (mm).

_{x}and v

_{y}are the speed of the hook tip in the x and y directions (m/s).

_{x}> 0 does the picking film hook tooth have a horizontal forward speed to complete the picking film operation. At this time, the motion trajectory of the hook tooth is a trochoidal line. When ${v}_{x}=v-{L}_{OA}w\mathit{sin}wt=0$:

_{1}is the linear velocity of the hook tip (m/s).

_{1}of the pick-up hook tooth to the forward speed v of the machine be λ. According to the Formulae (7) and (10), it can be seen that when λ > 1, the pick-up hook tooth has a horizontal forward speed, and the pick-up chain rake rotation will pick up the residual film upward transport. If λ is too small, it is easy to make the residual film leak too much and reduce the work efficiency. If λ is too large, it is easy for the phenomenon of residual film return to appear. According to the preliminary experiment, when λ is 2.8~3.4, the test effect is better. At this time, the chain rake shaft speed can be preliminarily determined to be 210~258 r/min.

#### 2.2.3. Reliable Conditions for Residual Film Pickup

_{0}, and the A′ point is unearthed at time t

_{1}. The adjacent latter picking film hook tooth is buried at point B at time t

_{2}, and the B′ point is unearthed at time t

_{3}. In this process, the distance of the lower shaft axis of the chain rake is S

_{0}. In order to realize that the residual film does not leak during the picking process, the following conditions need to be met:

_{a}is the distance from the previous pickup hook tooth to the lower shaft of the unearthed chain rake (mm); S

_{b}is the distance between the adjacent rear pick-up film hook teeth and the lower shaft of the unearthed chain rake (mm).

_{OA}are substituted into Formula (23). The condition where the residual film is not missed in the picking process is $n\ge 118.7\mathrm{r}/\mathrm{min}$.

#### 2.2.4. Force Analysis of Residual Film in Conveying Process

_{n}is the support force of residual film (N); m is the mass of residual film (kg); R is the instantaneous radius of the center of gravity of the residual film (mm); G is the acceleration of gravity (m/s

^{2}); f is the friction coefficient of the pickup hook tooth and residual film; P is the centrifugal force (N); ω is the chain rake shaft rotation angle (rad/s); θ is the residual film in the direction of the gravity angle (°); β is the angle between the support force and centrifugal force (°).

#### 2.3. Analysis of the De-Filming Process

_{b}tends to 0. In the process of film removal, when the film removal device and the hook tooth assembly move relative to each other, the condition that the residual film is separated from the hook tooth at this time is

_{1}= mω

_{2}

^{2}r

_{t}and G = mg.

_{1}is the force of the stripping device on the hook tooth (N); F

_{n}is the support force of the hook tooth on the residual film (N); m is the mass of the residual film carried by the hook tooth (g); G is the gravity of the residual film (N); r

_{t}is the rotation radius of the stripping device m. g is the acceleration of gravity, m/s

^{2}; ω

_{2}is the angular velocity of rotation of the de-filming axis rad/s; f is the friction force between the residual film and the hook tooth (N); F

_{b}is the centripetal force generated by the motion of the residual film (N); β is the angle between the center of the de-filming axis and the line connecting the contact point and the horizontal direction (°); γ is the angle between the hook tooth rod and the vertical direction during the de-filming operation (°).

#### 2.4. Field Tests

#### 2.4.1. Test Materials

#### 2.4.2. Test Methods

_{1}and the residual film impurity rate μ

_{2}were determined as test indicators in conjunction with the actual operation. Use Formula (28) to calculate the residual film pick-up rate and Formula (29) to calculate the residual film impurity rate. Before the test, the total mass G

_{1}, of the film laid at the test site was calculated by measuring the film mass of one square meter by electronic balance. After the test, the residual film left at each detection point was collected, and the total mass of the residual film G

_{2}, was measured by electronic balance. The total mass of residual film impurities G

_{3}, was measured by electronic scale. The impurities in the residual film of the cleaning machine were manually picked up, and the mass G

_{4}, of the impurities was measured by an electronic balance.

_{1}is the residual film pick-up rate %; μ

_{2}is the residual film impurity rate %; G

_{1}is the total mass of film laid at the test points in the test plot g; G

_{2}is the mass of residual film left at each test point g; G

_{3}is the total mass of film impurities g; G

_{4}is the mass of impurities in the film impurities g.

#### 2.4.3. Test Results

## 3. Results and Discussion

_{1}and μ

_{2}on X

_{1}, X

_{2}, and X

_{3}was tested.

- (1)
- Establishment of the regression equation and significance analysis of the residual film pick-up rate

_{1}> X

_{3}> X

_{2}. The p-value of 0.0763 for the lack of fit of the residue picking rate was not significant, indicating that the regression model was valid and accurate, and that it could be used to analyze and predict the residue picking rate [19]. After removing the non-significant term, the regression equation for each factor’s effect on the residual film pick-up rate μ

_{1}was as follows:

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

_{1}> X

_{3}> X

_{2}. The p-value of 0.1549, for the lack of fit of the residual film impurity rate, was not significant, indicating that the regression model was valid and accurate, and that it could be used to analyze and predict the residual film impurity rate. After removing the non-significant term, the regression equation for each factor’s effect on the residual film impurity rate μ

_{2}was as follows:

#### 3.1. Response Surface Analysis

- (1)
- Analysis of the influence of the residual film pick-up rate

_{1}and X

_{2}on the residual film pick-up rate when X

_{3}is at the central level (234 rpm). As shown in the graph, the residual film pick-up rate in X

_{1}and X

_{2}of interaction increases first and then decreases, with X

_{1}increasing first and then decreasing, and X

_{2}increasing first and then decreasing. On the residual film pick-up rate response surface, Figure 13b for X

_{2}is located in the center level (40 mm) of the X

_{1}and X

_{3}interaction. As shown in the graph, the residual film pick-up rate increases and then decreases due to the interaction between X

_{1}and X

_{3}, and increases and then decreases as X

_{1}increases, and increases and then decreases as X

_{3}increases; Figure 13c depicts the response of X

_{1}at the center level (1.5 m/s), as well as the interaction between X

_{2}and X

_{3}. The graph depicts the effect of X

_{2}and X

_{3}interaction on the film pick-up rate. As shown in the graph, the residual film pick-up rate in X

_{2}and X

_{3}interactions increases first and then decreases, with X

_{2}increasing first and then decreasing, and X

_{3}increasing first and then decreasing [20,21].

_{1}, the poorer the ability of the hook teeth to pick up film continuously per unit length, and the subsequent hook teeth cannot pick up residual film sufficiently, resulting in a lower rate of picking up residual film. The faster X

_{1}, the easier it is for the hook teeth to tear the residual film per unit length, which will also cause the residual film pick-up rate to decrease; X

_{2}has no significant effect on the residual film pick-up rate, which is due to the fact that the residual film in the field is mainly concentrated in the surface layer of the soil, so it is difficult to increase X

_{2}to improve the residual film pick-up rate; when X

_{3}is slower, the hook teeth are subject to soil resistance for a longer period of time and are easily de-formed and damaged, resulting in the pick-up residual film performance decline. When X

_{3}is faster, the hook teeth will cause a large impact on the residual film, which is not conducive to pick-up of the residual film.

- (2)
- Effect of factor interaction of the residual film impurity rate

_{1}and X

_{2}on the residual film rate when X

_{3}is at the central level (234 rpm). As shown in the figure, the residual film impurity rate in X

_{1}and X

_{2}of interaction under the influence of the first decrease and then increase, with X

_{1}increasing first decrease and then increasing, and X

_{2}increasing first decrease and then increasing; Figure 13e shows an interaction of X

_{1}and X

_{3}on the residual film impurity rate of response surface diagram with X

_{2}located in the center of the level (40 mm). The residual film impurity rate in X

_{1}and X

_{3}interactions can be seen in the figure, with X

_{1}increases first decreasing and then increasing, and X

_{3}increases first decreasing and then increasing. In Figure 13f, X

_{1}is located in the center of the level (1.5 m/s), and X

_{2}and X

_{3}interact on the residual film impurity rate response surface plot. The graph depicts the effect of the interaction between X

_{2}and X

_{3}on the residual film impurity rate. As shown in the graph, the residual film impurity rate in X

_{2}and X

_{3}interactions is first reduced and then increased, with X

_{2}increases first reduced and then increased, and X

_{3}increases first reduced and then increased.

_{1}, the faster the hook teeth disturb the soil per unit length, resulting in an increase in the proportion of impurities picked up. The faster X

_{1}, the lower the residual film picking capacity of the hook teeth, but the picking of impurities on the film surface remains at a high level, resulting in a higher rate of residual film impurity. If X

_{2}is too shallow, the amount of residual film picked up decreases, but the rate of picking up impurities on the film surface increases. If X

_{2}is too deep, the impurities in the tillage layer will be picked up, resulting in a higher residual film impurity rate. When X

_{3}is too slow, the hook teeth are subject to greater resistance from the soil and are easily deformed and damaged, which is not conducive to the picking up of the residual film, but the effect of picking up the impurities on the residual film surface is not significant and can also cause the residual film impurity rate to be higher. When X

_{3}is too fast, the cleaning device’s duration of time for cleaning impurities is shorter, and the impurities cannot be separated in time, resulting in a higher residual film impurity rate.

#### 3.2. Parameter Optimization and Test Validation

#### 3.3. Discrete Element Modeling of Hook Tooth Motion Process

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

^{−6}, the simulation time is one second, and the grid cell size is 3 times the minimum soil particle size. The contact model is chosen from soil particles and a hook tooth, and the main parameters are contact parameters and intrinsic parameters, with the contact parameters being soil recovery coefficient, static friction coefficient, and dynamic friction coefficient, and the intrinsic parameters being density, Poisson’s ratio, and shear modulus. The data for the main parameters of the discrete element method test model were obtained using the method of calibration and optimization of the stacking test discrete element parameters [25,26,27], in which the soil parameters were obtained from the gray desert soil, which itself is the most widely distributed soil type in Shihezi, Xinjiang. The relevant parameters are shown in Table 6.

#### 3.3.2. Analysis of Simulation Results

_{b}] = 1230 MPa, and while this time the safety factor under the established working conditions is 5.71, the stress value is much less than the allowable stress, so the hook tooth design meets the requirements.

## 4. Conclusions

- 1.
- In response to the problems of high residual film pick-up rate and poor reliability of the existing film recovery machine, a Hook-and-Tooth Chain Rail Type Residual Film Picking Device was designed, introducing the structure and working principle of the main components. By analyzing the main working components of the picking device, the main design parameters of its components were determined.
- 2.
- Field tests were carried out with the machine advancing velocity, depth of hook tooth, and chain rake input speed as influencing factors and the residual film pick-up rate and residual film impurity rate as test indicators. Additionally, the response surface data were analyzed using Design Expert software, and multiple fittings obtained the regression equation of the residual film pick-up rate and the residual film impurity rate. The influence of the interaction of various factors on the residual film pick-up rate and the residual film impurity rate was determined.
- 3.
- Experimental tests on the device proved that when the machine advancing velocity was 1.6 m/s, the depth of the hook tooth was 38 mm, and the chain rake input speed was 241 rpm. With these working parameters, field trials yielded a residual film pick-up rate of 87.52% and a residual film impurity rate of 10.21%. The optimized operating parameters were verified experimentally. Relative errors between the experimental results and optimized theoretical values of the residual film pick-up rate and residual film impurity rate were 0.85% and 2.51%, respectively, which is relatively low. Thus, the model was highly reliable.
- 4.
- EDEM simulated the motion process of the hook tooth and obtained the maximum force on the hook tooth during the working process. Then, ANSYS software was used to analyze the stress and deformation of the hook tooth under the state of maximum force, and the structural strength of the hook tooth was verified to meet the design requirements.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

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**Figure 1.**The residual film recycling machine: 1. Traction frame; 2. Power transmission system; 3. Straw crushing device; 4. Mulch storage and pushing out device; 5. Machine frame; 6. Wheels; 7. Hook-and-tooth chain rail type residual film picking device.

**Figure 2.**Hook-and-tooth chain rail type film picking device: 1. Chained rake frame upper shaft assembly; 2. Hook tooth assembly; 3. Guide beam; 4. Curved edge conveyor chain; 5. Chain rake frame lower shaft assembly; 6. Flap for discharging debris; 7. Chain rake frame; 8. Mounting plate; 9. De-filming shaft; 10. Prevention of mulch sucking back parts; 11. Articulated short shaft. (

**a**) the main components of the picking device, (

**b**) Pick up film chain rake structure schematic diagram.

**Figure 3.**A schematic diagram of the hook and tooth assembly structure: 1. Limit short shaft; 2. Guide side plate; 3. Roller; 4. Hook tooth mounting shaft; 5. Hook tooth; 6. Threaded fastener.

**Figure 4.**A schematic diagram of the rotation of the decapping area of the hook tooth assembly: 1. Hook tooth mounting shaft; 2. Hook tooth; 3. Short shaft; 4. Side guide plate; 5. Roller.

**Figure 5.**A schematic diagram of the hook tooth structure: (

**a**) Diagram of the influence of resistance of hook teeth into the soil; (

**b**) Axonometric drawing.

**Figure 7.**Working process of the film pickup device. (

**a**) Picking film process diagram, (

**b**) Motion diagram of the pick-up hook tooth.

**Figure 12.**A field test of the experimental device. (

**a**) Before the test; (

**b**) The test process; (

**c**) After the test.

**Figure 13.**The effects of the interaction of various factors on the picking rate and trash content of cotton fallen on the ground. (

**a**). μ

_{1}= (X

_{1}, X

_{2}, 234); (

**b**). μ

_{1}= (X

_{1},40, X

_{3}); (

**c**). μ

_{1}= (1.5, X

_{2}, X

_{3}); (

**d**). μ

_{2}= (X

_{1}, X

_{2}, 234); (

**e**). μ

_{2}= (X

_{1}, 40, X

_{3}); (

**f**). μ

_{2}= (1.5, X

_{2}, X

_{3}).

**Figure 14.**A particle and geometric simulation model. (

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

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

Main Parameters of the Picking Device | Value |
---|---|

Structure form | Traction type |

Dimension (length × width × height)/mm | 2240 × 880 × 3170 |

Matched power/kW | 88.20 |

Operating speed/(km·h^{−1}) | 4–8 |

Effective operating width/mm | 1875 |

Residual film pick-up rate/% | ≥85 |

Residual film impurity rate/% | ≤12 |

Coded Value | Machine Advancing Velocity X _{1} (m·s^{−1}) | Depth of Hook Tooth X _{2} (mm) | Chain Rake Input Speed X_{3} (rpm) |
---|---|---|---|

−1 | 1.0 | 20 | 210 |

0 | 1.5 | 40 | 234 |

1 | 2.0 | 60 | 258 |

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

1 | 0 | −1 | −1 | 84.1 | 13.4 |

2 | 1 | 1 | 0 | 83.8 | 13.2 |

3 | 1 | 0 | 1 | 85.2 | 11.6 |

4 | 0 | 0 | 0 | 87.6 | 10.5 |

5 | 0 | 0 | 0 | 88.5 | 9.8 |

6 | 1 | −1 | 0 | 82.8 | 13.6 |

7 | 0 | 0 | 0 | 88.1 | 10.2 |

8 | 1 | 0 | −1 | 80.7 | 15.3 |

9 | 0 | 1 | −1 | 82.3 | 14.1 |

10 | −1 | 0 | −1 | 82.4 | 14.2 |

11 | 0 | 1 | 1 | 84.8 | 12.6 |

12 | 0 | 0 | 0 | 88.2 | 10.3 |

13 | 0 | 0 | 0 | 87.9 | 10.3 |

14 | 0 | −1 | 1 | 85.3 | 11.4 |

15 | −1 | 0 | 1 | 78.2 | 16.4 |

16 | −1 | −1 | 0 | 81.3 | 14.7 |

17 | −1 | 1 | 0 | 79.2 | 16.1 |

Source of Variation | DOF | Residua Film Pick-Up Rate μ_{1}/% | Residua Film Impurity Rate μ_{2}/% | ||||
---|---|---|---|---|---|---|---|

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

Models | 9 | 165.94 | 4.46 | <0.0001 ** | 74.63 | 65.92 | <0.0001 ** |

X_{1} | 1 | 16.24 | 19.22 | 0.0001 ** | 7.41 | 58.92 | 0.0001 ** |

X_{2} | 1 | 1.44 | 3.01 | 0.0671 | 1.05 | 8.36 | 0.0233 * |

X_{3} | 1 | 2.00 | 1.61 | 0.0382 * | 3.13 | 24.84 | 0.0016 ** |

X_{1} X_{2} | 1 | 2.4025 | 9.68 | 0.0268 * | 0.8100 | 6.44 | 0.0388 * |

X_{1} X_{3} | 1 | 18.92 | 3.58 | <0.0001 ** | 8.70 | 69.19 | <0.0001 ** |

X_{2} X_{3} | 1 | 0.4225 | 0.70 | 0.2799 | 0.0625 | 0.4969 | 0.5036 |

X_{1}^{2} | 1 | 81.24 | 0.23 | <0.0001 ** | 33.96 | 269.99 | <0.0001 ** |

X_{2}^{2} | 1 | 15.08 | 1.89 | 0.0002 ** | 7.56 | 60.11 | 0.0001 ** |

X_{3}^{2} | 1 | 17.57 | 0.25 | 0.0001 ** | 7.28 | 57.88 | 0.0001 ** |

Residual | 7 | 2.16 | 0.8805 | ||||

Lack of fit | 3 | 1.70 | 1.96 | 0.0763 | 0.6125 | 3.05 | 0.1549 |

Pure error | 4 | 0.4520 | 0.2680 | ||||

Total | 16 | 168.10 | 75.51 |

Parameter | Residua Film Pick-Up Rate μ _{1}/% | Residua Film Impurity Rate μ _{2}/% |
---|---|---|

Theoretical optimization value | 88.27 | 9.96 |

Test average | 87.52 | 10.12 |

Relative error | 0.85 | 2.51 |

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

Soil particles | Poisson’s ratio | 0.30 |

Shear modulus/Pa | 5 × 10^{7} | |

Density/(kg·m^{−3}) | 2600.00 | |

Hook teeth | Poisson’s ratio | 0.35 |

Shear modulus/Pa | 7.27 × 10^{10} | |

Density/(kg·m^{−3}) | 7890.00 | |

Soil particles-Soil particles | Recovery coefficient | 0.21 |

Static friction coefficient | 0.68 | |

Dynamic friction coefficient | 0.27 | |

Soil particles-Hook teeth | Recovery coefficient | 0.32 |

Static friction coefficient | 0.54 | |

Dynamic friction coefficient | 0.13 |

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## Share and Cite

**MDPI and ACS Style**

Cao, S.; Xie, J.; Wang, H.; Yang, Y.; Zhang, Y.; Zhou, J.; Wu, S.
Design and Operating Parameters Optimization of the Hook-and-Tooth Chain Rail Type Residual Film Picking Device. *Agriculture* **2022**, *12*, 1717.
https://doi.org/10.3390/agriculture12101717

**AMA Style**

Cao S, Xie J, Wang H, Yang Y, Zhang Y, Zhou J, Wu S.
Design and Operating Parameters Optimization of the Hook-and-Tooth Chain Rail Type Residual Film Picking Device. *Agriculture*. 2022; 12(10):1717.
https://doi.org/10.3390/agriculture12101717

**Chicago/Turabian Style**

Cao, Silin, Jianhua Xie, Hezheng Wang, Yuxin Yang, Yanhong Zhang, Jinbao Zhou, and Shihua Wu.
2022. "Design and Operating Parameters Optimization of the Hook-and-Tooth Chain Rail Type Residual Film Picking Device" *Agriculture* 12, no. 10: 1717.
https://doi.org/10.3390/agriculture12101717