Experimental Study on Performance of Cotton Small Arch Shed Recovery Machine

Abstract

Most of the small-arch-shed-recycling machines in China use manual disassembly and manual recycling, with low recycling efficiency and low mechanization. Therefore, this paper designs a small recovery machine for arch sheds, greatly improving the efficiency of the recycling of arch sheds, which can realize the lifting and collection of the arch shed rod and orderly recycling of the shed film. By performing univariate experimental studies in the field, on the basis of field experiments, we carried out an experimental analysis with machine speed and different soil moisture contents as the influencing factors and took the removal rate of the shed rod, the removal rate of the shed film, and the damage rate of seedlings as the test indexes. The test results show that the optimal parameter combination is a travel speed of 1.1 m/s, at which the operation effect is the best. The results show that under the optimal operation effect, the removal rate of the shed rod was 95.72%, the removal rate of the shed film was 98.63%, the seedling injury rate was only 2.11%, and the removal rate of the shed rod was only 4.01%, which met the requirements of the recovery operation of the arch shed and means that this approach is conducive to the recycling of the arch shed materials and the realization of sustainable development. In actual operation, the parameters should be adjusted according to the actual situation in the field to meet the different recovery needs of arch sheds.

1. Introduction

Xinjiang is China’s largest cotton planting area. The whole planted cotton area of Xinjiang is more than 40 million mu. In order to achieve the green production of cotton in Xinjiang, the residual film pollution and other white pollution problems must be completely solved. This can be achieved via research and development regarding the cotton small-arch film-mechanized planting mode of the arch shed support and shed film with integrated recycling technology and equipment. The sustainable recycling of shed film must be realized. It is well known that the small arch shed covering cultivation technology of crops can improve the ground temperature, prevent the freezing damage of seedlings, resist drought and retain moisture, inhibit the growth of weeds, and so on, which can greatly improve crop quality and yield and has extremely important strategic significance for the sustainable development of dryland agriculture [1,2,3].

In Western countries, research on horticultural facility machinery has taken place, the research field is more extensive, and the facility machinery and equipment are more mature. As far as the current research situation of the arch-shed-recycling machine is concerned, it can be generally divided into three categories: the rod harvester, which only recycles the support of the arch shed during operation; the film-rolling machine, which only recycles the shed film during operation; and the film-collecting rod-integrated machine, which can complete multiple operations of the film-collecting rod in one operation. In France, in CM-REGERO INDUSTRIES’ production of the L ‘Arracheuse D ‘Arceaux arch-support-recovery machine, the machine-matched tractor power needs to be more than 30 kW. The machine’s mechanization automation level is high, but the machine-specific volume is large. It has poor mobility and is only suitable for field operations. The MKF-75B film-rolling machine developed by the Japanese Rattan Agricultural Machinery Manufacturing Institute can simultaneously peel and wind the film on the film-rolling roller and can achieve a speed of 50 m/min. The tension of the film driving the machine forward can better realize the synchronization of the film rolling. When turning, the front wheel floats in place, and the rear wheel drives the front wheel to achieve easy turning [4,5,6,7]. The wheel width can also be adjusted according to the actual span of the field arch shed, the width of the wheel base can be adjusted in the range of 90~175 cm, and the height of the shed film is better matched under the condition of 75 cm. The machine is light and flexible, and the fuselage size utilization rate is high. It is suitable for field, hill, or large arch shed internal operation, and its adaptable performance is good. However, the machine can only roll the film, it cannot close the rod, and it relies on manual operation. This is coupled with its repeated walking start and stop and motor reset operation control, poor reliability, and low durability [8,9,10,11,12].

Based on the above foreign research status and progress, most of the shed film used in developed countries is relatively thick, the shed film is stronger and not easy to break, the shed film is easy to recycle, and the shed rod material is mostly glass fiber or a steel frame structure. The mechanization of recycling shed rods is also relatively easy to realize. The material and structure of relevant facilities in China are very different, so it is difficult to directly copy and apply the techniques used elsewhere. The existing simple recycling machines in China generally have a low degree of integration of agricultural machinery research and agronomic requirements and different crop planting patterns and requirements for the use of arch sheds, and it is difficult to improve their mechanical parts, so the universality and adaptability are poor [13,14,15,16]. Finally, there are higher requirements for the operator’s proficiency, and there are more unreasonable matches between the manual film-rolling and rod-pulling devices. Therefore, it is imperative to develop specialized and efficient technology and equipment for small arch shed recycling [17].

In order to solve the above problems and provide a new green development technology for sustainable agriculture and methods for planting cotton in Xinjiang, a small-arch-shed-recycling machine is designed and manufactured in this study. The folding shed machine is based on market demand, and the inserted shed machine support, which is fully mechanized, can be used in late planting periods with machinery to remove the unused arch shed film and rod. This is a special research and development area of the machine, saving a lot of manual work. In the end, the effect of film and rod collection is verified through a field experiment, and the performance of the machine is evaluated.

2. Materials and Methods

2.1. Cotton Small Arch Shed Film-Recovery Machine: Whole Structure and Complete Machine Working Principle

2.1.1. Whole Structure

The whole machine can be suspended and pulled by a tractor, and the whole machine is composed of a frame, a mechanical transmission mechanism, a hydraulic transmission system, a film-receiving mechanism, and a rod-closing mechanism. The specific three-dimensional structure is shown in Figure 1, and a physical picture is shown in Figure 2. The whole arch shed is recovered in length, width, and height (2450 mm × 1700 mm × 1800 mm). The rubber ground wheel drive method is used in the roll film recovery link through the ratio of reduction gear, matching the appropriate tension to pull the film, not only to ensure that the film is fast in the process of rolling back, but also providing moderate tension, having a single layer of film in the roll back to maintain flatness, and ensuring the gap between the layers to prevent aging [7,8].

Combined with the characteristics of cotton planting in small arch sheds, the main technical parameters of the machine are shown in

Table 1. Technical parameter table of cotton small-arch-shed-recycling machine.

Project	Technique Parameters
Hang way	Tractor traction type
Supporting power (metric horsepower)	≥80
Suitable for recycling shed pole height distance (tunable, mm)	400–800
Array pitch; row pitch (mm)	1100
Suitable for recycling arch shed span (tunable, mm)	800–1200
Adapt to membrane width (cm)	900–1200
Machine dimension (L × W × H: mm)	2450 × 1700 × 1800
Complete machine quality (kg)	About 1250 kg
Number of operators	2
Clearance rate of shed pole (%)	≥98
Recovery rate of shed film (%)	≥95
Production efficiency (mu/hour)	6–10

.

2.1.2. Cotton Small-Arch Film-Recovery Machine Whole Structure and Working Principle

The small-arch film-recovery machine is connected with the tractor suspension used in the matching, and the main supply oil pipe and main return oil pipe of the hydraulic system are connected to the control valve [18,19,20]. The locomotive is driven to the field where the shed is to be lifted: first, the shed film is manually rolled onto the large roll of the mechanical film collection, the hydraulic handle is pushed to the hydraulic motor of the transmission mechanism of the upper and lower lifting rod, the synchronous toothed belt transmitting up and down begins to work, and the center is aimed at the shed rod to be lifted. The tractor is steered forward, and the ground wheel drives the transmission mechanism, so that the film-rolling stick runs at the same time, and the rod mechanism constantly pulls up the shed rod, which is transported to the collection trough at the back upper part through the conveyor toothed belt and slide. When the film roll and pole collection tank are full, the machine stops, cuts the membrane, removes the collected membrane and pole, and carries out the next cycle of operation. The process of film collection and pole collection is shown in Figure 3.

2.2. Planting Agronomic Requirements

The agronomic parameters of the small arch shed used to cultivate cotton are shown in Figure 2. The shed height is 700 mm, the shed width is 900 mm, and the shed pole array spacing and row spacing are both 1100 mm. A white covering with a width of 1200 mm and a thickness of 0.015 mm is used. The actual planting agronomy model and the field planting agronomy are shown in Figure 4.

2.3. Analysis Design of Key Mechanism

2.3.1. Closing Mechanism

The structure of the clamping and pulling device of the arch bar is shown in Figure 5, which is mainly composed of a clamping device, synchronous toothed belt, tension device, limit plate, and other parts. The function of the clamping device is as follows: when the closing mechanism travels at a certain speed on the arch, the arch pole is clamped and pulled up along the synchronous toothed belt and transported to a predetermined position for collection. The forward speed of the arch shed recovery machine must be equal to and opposite to the horizontal speed of the speed of the clamping synchronous toothed belt, so as to ensure that the arch shed rod is pulled up vertically, as shown in Figure 6. The clamping device is comprised of a double-row clamping chain, a double-row sprocket, and a clamping chain drive shaft.

The collecting mechanism realizes the pulling action of the lever by the active clamp constraint of the synchronous toothed belt (Figure 6). When the synchronous toothed belt holds the carrier rod, it actively restricts the movement attitude and trajectory of the shaft. In order to avoid the rebound force of the carrier rod after the end of the rod is reached, the middle line is located in the middle of the roller, and the roller wheel is installed at a 30 degree angle. The bottom of the roller toothed belt, the height of the recovery table, the forward speed of the machine, and the holding force of the roller are all closely related. To verify this relationship, it will be analyzed in subsequent studies.

2.3.2. Design of Film-Receiving Mechanism

The film-rolling mechanism is mainly composed of an outer film-rolling baffle, a film-rolling roller, an inner film-rolling baffle, a roller, and a film-rolling shaft, as shown in Figure 7. The film-rolling mechanism is axisymmetrically distributed with the roller as the axis of symmetry. The outer baffle plate of the rolling film has a sleeve, the inner baffle plate of the rolling film has a bulge, and the outer baffle plate of the rolling film is connected with the inner baffle plate through the film-rolling roller. A film-raising nail is installed on one side of each film-rolling roller near the outer baffle plate. Both ends of the film-rolling shaft extend to the outside of the outer baffle plate and are fixed with positioning pins. The overall structure is easy to disassemble, and the recovered side film can be removed by removing the external baffle.

2.3.3. Design of Rolling Mechanism Structure

During operation, the film-rolling mechanism relies on the hydraulic output force of the tractor to drive the film-rolling roller to rotate. With the rotation of the film-rolling mechanism, the edge film is wrapped around the film-rolling roller to complete the shed film recovery work. The film-rolling mechanism needs the roller to perform pure rolling during the working process. If the roller slides relative to the ground, it will directly cause the pull of the shed film and cannot effectively recover the side film. In order to avoid this phenomenon, teeth are added to the roller to increase the friction between the roller and the film, but the shed film will be deformed due to the force when the film-rolling mechanism recovers the shed film in the actual working state.

2.3.4. Checking Analysis of the Shaft on the Clamping Chain of the Synchronous Toothed Belt of the Closing Lever Mechanism

In the design of the small-arch-shed-recycling machine, the main working part of the closing rod mechanism is the double-row synchronous toothed belt clamping chain. The driving ends of these two parts are gear shaft parts, and the strength of the drive shaft of the double-row synchronous gear belt is checked here [21,22,23]. Due to the large load on the shaft, the mechanical manual was consulted, and the following parameters were selected: 45CrNi modulated steel, hardness HBS = 280, strength limit σ_B = 950 MPa, yield limit σ_C = 740 MPa, bending fatigue limit σ₋₁ = 450 MPa, allowable bending stress [σ₋₁] = 70 MPa.

According to the design requirements, the power consumed by the receiving rod mechanism is P = 2.55 kW, and the speed N-axis of the double-row clamping chain is calculated from the transmission ratio of the power output head and the transmission system. The input power is 108 r/min and the P input = 2.7 kW. The gear modulus m = 4 mm and the number of teeth z = 20, according to the torque formula:

T = 9,550,000 P/n

The torque T acting on the gear is calculated. The circumferential force Ft, radial force Fr, and axial force Fa acting on the gear are calculated from the known linear speed of the clamping sprocket. And the power consumption of the gripper pulling P is calculated with the following formula:

Fe = 1000 Pν     FP = k_FPFe(k_FP = 1.1)

The circumferential force on the clamping sprocket and the axial pressure acting on the shaft are calculated. The horizontal and vertical supporting forces of the bearing are calculated according to the force balance condition on the upper shaft of the double-row clamping chain.

The strength of the section of the shaft under the maximum bending moment and torque must be checked according to the following formula:

$${\sigma }_{\mathrm{ca}}={\displaystyle \frac{\sqrt{M^2+{(\alpha T)}^2}}{W}}$$

According to the previous calculated value, the calculated stress of the shaft is σ = 65.58 MPa, which meets the requirements. The calculation method of other working axes is the same. The strength and stiffness of all axes calculated by checking the table meet the requirements, and there will be no bending change or force fracture.

2.4. Field Testing

2.4.1. Test Place and Test Instrument

From 16 to 17 May 2024, the experimental demonstration of the cotton small arch shed film-recycling machine was carried out in Laowan Town, Shawan City, Tacheng District, Xinjiang Uygur Autonomous Region, China. An on-site cotton small-arch-film-recycling mechanized technology meeting was held, and the machine and tools were tested on-site. The test instruments include a steel tape ruler, an angle ruler, a stopwatch, and so on. According to the agronomic conditions of cotton arch shed planting, the working parameters of transplanter were set to match with the appropriate planting distance and planting row distance. In this test, the agronomic parameters of the arch shed were as follows: shed height 700 mm, shed width 900 mm, and shed pole array spacing and row spacing 1100 mm. The section diameter of the pole is 6 cm, the length of the pole is 170 cm, and the material is glass fiber. The arch film used is a white plastic film covering with a width of 1200 mm and a thickness of 0.015 mm. The working test of the small-arch-shed-recycling machine is shown in Figure 8, and the effect diagram after recycling the arch shed is shown in Figure 9.

2.4.2. Testing Methods

The small-arch-shed-recycling machine belongs to the planting technology and method of cotton arch shed sustainable dryland agriculture. Therefore, we referred to GB/T 25412-2021 “Residual mulch recycling machine” [24] and DB65/T4580-2022 “Cotton stalk harvesting machinery Operation Quality” [25] and adopted the relevant provisions of those test methods.

The experiment was carried out during the planting period of a cotton small arch shed, and the influence of the running speed of the recycling machine on the removal rate of the shed rod, the removal rate of the shed film, and the seedling injury rate was analyzed. The corresponding test methods are as follows.

There was 1 test area around and in the middle of the working block and a total of 5 test areas. Three random measurements were conducted in each test area. The total number of arch shed rods within a distance of 15 m, the number of arch shed culms pulled out, the number of arch shed culms missed, the quality of the successfully recovered arch shed film, and the total number of plants and seedlings damaged by machine harvesting in the test area before and after operation were counted, and the data were recorded.

(1)

The removal rate of the arch bar

The percentage of the number of pull-out arch bars to the total number of arch bars is the pull-out ratio of arch bars, calculated according to Formula (1):

U = z₁/z

(1)

The parts of the above formula are as follows:

• U—The vault rod removal rate, where unit is percentage (%);
• z₁—The number of arch culms pulled out, in units (units);
• z—The total number of vault poles, in units (units).

(2)

Shed rod leakage rate

The percentage of the number of missed and pulled vault poles to the total number of vault poles is the missed and pulled ratio of vault poles, calculated according to Formula (2):

U = z₂/z

(2)

The parts of the above formular are as follows:

• U—The vault rod removal rate, where the unit is percentage (%);
• Z₂—The number of missed and drawn arch shed poles, in units (each);
• z—The total number of vault poles, in units (units).

(3)

The net rate of shed film

Before the operation, the shed film in a continuous 5 m long piece in the test site was washed and dried, and its quality is called M₀. After the recovery operation of the small-arch-shed-recycling machine, a small area of film with a width and length of 5 m was randomly selected in the measurement area, all the recovered shed film was removed, and the film was dried after washing to analyze its quality. Then, the net rate of the shed film was calculated according to the following formula, where the test was repeated three times and the average was taken.

M = M₁/M₀

The parts of the above formula are as follows:

• M—The membrane net rate, where the unit is percentage (%);
• M₀—The average value of the film quality at each test point before operation, in (g);
• M₁—The average value of the film quality at each test point after operation, in (g).

(4)

Damaged seedling rate

The total number of plants in each test point in the test area after the operation and the number of injured seedlings caused by the recovery operation of the arch shed were measured, and the injured seedling rate of each test point was calculated according to the following formula. Then, the average of the injured seedling rate of the three test points was calculated, and the average was taken as the injured seedling rate of the test area.

S = T/T₀

The parts of the above formula are as follows:

• S—Seedling injury rate, where the unit is percentage (%);
• T—The number of injured seedlings after the operation, where the unit is (plant);
• T₀—The total number of plants before the operation, where the unit is (plant).

3. Results

Plots with different water contents were selected for the test (25.5%, 21.3%, 20.1%, and 18.2%). At the beginning of the test of the small arch shed recovery machine, the effects of the machine walking speed of 0.9 m/s, 1.1 m/s, 1.3 m/s, and 1.5 m/s on the removal rate of the shed rod, the removal rate of the shed film, and the damage rate of the seedlings were measured, and the reasons were analyzed. The specific test data table is shown in Figure 10a–d.

A single-factor analysis was performed based on the data from the field experiment. Figure 10a–d show the analysis results. In the dryland soil with a water content of 18.2~25.5%, the running speed and mechanical speed increased, the removal rate of the shed rod increased, the removal rate of the shed rod and the shed film net increased first and then decreased, and the seedling injury rate decreased first and then increased. When the machine speed is 1.1 m /s, the shed rod leakage rate and seedling injury rate are the lowest. At this time, the removal rate of the ceiling rod and the removal rate of the ceiling film are the highest, which are 95.72% and 98.63%, respectively.

Through the experimental analysis and verification of the design of the small-arch-shed-recycling machine, some suggestions for the key contents of further research and development are put forward. Although the net rate of the arch bar and the net rate of the shed film of the small-arch-shed-recycling machine have reached the national standard, there is still a lot of room for improvement, and the next step should be further improved. The lack of statistical analysis of the data is a shortcoming of this paper. In the optimization, the following problems should also be considered: (1) To solve the problem of soil when rolling back the shed film, the solution is to add a bow frame to prop up the film from the inside out to arch out the soil. (2) To solve the problem of flattening into the roll when the film is rolled back, the solution is to increase the upper and lower two jujube-shaped wheels to prop up the film so that it is not concentrated, then stretch the film and roll it back. (3) To solve the unidirectional toothed belt grab rod imbalance that makes it easy for the film to fall off the rod, the solution is to change to a double-sided toothed belt, and always push the rod into the slot and squeeze it so that is does not fall. (4) To solve the problem of inconvenient film loading and unloading in the field, the solution is to add a self-unloading device on the rack to provide about 150 kg of full film loading and unloading capacity.

4. Discussion

This paper designs a small arch shed recovery machine, which can complete the synchronous recovery and sustainable utilization of the shed film, but through the test, there are some points to be solved in the subsequent research: (1) how to solve the damage of the shed film caused by the soil on both sides of the film; (2) how to solve the one-way toothed belt grip rod imbalance that makes it easy to drop the rod; (3) how to solve the mismatch between the speed and the ground wheel chain transmission after the film thickening; (4) how to solve the inconvenience of loading and unloading the membrane roll in the field. In view of the above problems, the author proposes the following solutions, corresponding to the above problems: (1) increase the arch frame to support the film from the inside to the outside; (2) switch to a double-sided toothed belt to push the rod to design an electronic speed-regulating device or bevel gear variable speed-shifting device to increase the size of the membrane coil, to increase the time of changing the shaft, and to improve the efficiency; (4) increase the crane on the rack to provide a lifting capacity of about 150 kg.

5. Conclusions

In this study, a small arch shed recovery machine was designed and developed, and its structure and working principle were introduced. The extraction of the shed rod was realized by way of synchronous toothed belt clamping and pulling, and the technology of shed film effective rewinding was developed. The technical term for recycling the arches is in the category of sustainable agriculture.

On the basis of a single-factor test, with the machine speed and different soil moisture contents as the influencing factors and the removal rate of the shed rod, the removal rate of the shed film, and the damage rate of seedlings as the test indexes, the test analysis was carried out. The test results show that the optimal parameter combination is the premise of travel speed of 1.1 m/s, and the operation effect is the best. The results show that under the optimal operation effect, the removal rate of the shed rod was 95.72%, the removal rate of the shed film was 98.63%, the seedling injury rate was only 2.11%, and the removal rate of the shed rod was only 4.01%, which met the requirements of the recovery operation. The actual operation parameters should be adjusted according to the actual situation in the field to meet different needs.