Design and Test of Automatic Feeding Device for Shed Pole of Small-Arched Insertion Machine

Abstract

China’s small-arched shed-building machinery mostly adopts manual pole casting and mechanical planting, which have low building efficiency and mechanization. Therefore, we designed an automatic feeding device for shed poles to realize automatic single separation, orderly conveyance and timely dropping of poles. Considering shed pole-pitching pass rate as the evaluation index for the regression model, we adopted a three-factor, three-level experimental design and established the speed of the reclaiming ring, height of the falling shed poles and reclaiming ring spacing as the main influencing factors, obtaining 23.94 r/min, 408.799 mm and 1350 mm, respectively in experiments with a trellis qualification rate of 95.36%. Design-Expert 13 was used to perform analysis of variance and determine the optimal parameter combinations. The average measured trellis qualification rate in tests with the bench adjusted and the optimal parameter combination was 94.23%, with 1.13% relative error between test and theoretical optimization values. This confirmed the optimal parameter combination’s dependability. In field verification test results, pick-up card ring speed was 24 r/min; height of trellis pole drop, 410 mm; pick-up card ring spacing, 1350 mm; and pitching rate, 95.37%, obtaining 0.01% error compared with theoretically optimized values. The prototype operational performance was stable and satisfied design requirements.

1. Introduction

China’s facility horticulture technology, after years of development, has undergone a comprehensive breakthrough and gradually become a system. Greenhouse arches are becoming increasingly widely used in vegetable cultivation, melon and fruit cultivation, and heat-preservation nurseries, with the advances in facility horticulture technology. China’s facility vegetables occupy 2.32 million hm² of sowing land, and the total area of China’s facility vegetables is 4.17 million hm², of which small- and medium-arch greenhouses comprise 29% [1,2]. Compared with open field cultivation, facility cultivation may overcome the constraints imposed by the external climate and environment, enabling the production of crops that are seasonal or anti-seasonal, thereby effectively resolving the issue of problematic planting during non-seasonal periods [3,4,5,6]. The simplest and least expensive small greenhouse structures are made of plastic film, bamboo, steel or glass fiber, among other materials. A trellis pole [7,8,9] is built into an arch-shaped shed and is insulated; the warming effect is not as severe as that in a large-scale greenhouse, and the land-use rate is higher, making it one of the highest yielding industries with the highest rate of return in agricultural facilities [10,11,12,13,14]. Consequently, adjusting the structure of the agricultural industry is crucial to increasing farmers’ incomes. Currently, the majority of small-arched greenhouse constructions are artificial, with flexible bamboo or wood strips used as the framework for the arched greenhouse. The arched greenhouse features double-handed bending with the two ends inserted into the earth to form an arch and are further covered with a plastic film for moisture retention and thermal insulation to prevent wind and freezing calamities [15,16,17,18].

At present, scholars or enterprises at home and abroad have conducted relevant research on small-arched greenhouse erection machinery. The Hoops Planting Machine model developed by CM-Regero Industries of France can realize the insertion operation, and the Mechanical Transplanter Wire Hoop and Tunnel Layer developed by Dubois Agrinovation of the United States can realize the traction. The Model 95 small-arched greenhouse insertion frame mulching compound operation machinery can be completed in one go shed pole bending, planting and mulching operations. The United States ANDROS company developed a support for single-row, double-row and three rows of simultaneous insertion frame mulching operations, greatly improving the operational efficiency. The Liu Ping team from the Shandong Agricultural University, developed an arch greenhouse automatic insertion device for the needs of domestic vegetable-planting users. The single-row double insertion of the integrated machine mulching can automatically complete the bending of pole-planting operations [19,20]. The Gong Yan team of the Nanjing Agricultural Mechanization Research Institute of the Ministry of Agriculture and Rural Development used a small-arched greenhouse mulching machine, to achieve small-arched greenhouse pole planting, covering the greenhouse membrane, membrane edge mulching and mechanized compound operation, thereby greatly improving the efficiency of the small-arched greenhouse erection [21]; however, the machine needs to be used in advance of the bending of the metal poles. The material and processing costs are also high. Jianling et al. designed rotary insertion of the racking mechanism using double-armed slewing, which greatly improves insertion efficiency [22]. Compared with the traditional manual work, the above models greatly reduce the labor intensity of farmers, who still need to bend down frequently to pick up the pole. The operation is cumbersome, and requires coordinating the speed of putting and speed of machine travel. In addition, because of manual casting, pole insertion can be easily missed, leading to uneven pole spacing phenomenon, which affects the small-arched trellis of the overall wind resistance [23,24]. The automatic feeding device is the key to ensuring the continuous operation of the automatic insertion machine for hanging small-arched trellis. At present, the existing insertion machine on the market is not equipped with an automatic feeding device; therefore, it cannot guarantee automatic insertion [25]. Liu Ping from the Shandong Agricultural University used the toggle wheel rod feeding mechanism. The device can realize a separate rod, but the trough cannot be placed in too many trellis rods. With troughs lacking and easy hollow phenomenon of the trellis rod, the rod cannot be directly placed into the elongated material groove, generating the separation effect [26].

In this study, an automatic feeding device was designed for a small-arch greenhouse insertion machine, to ensure single separation, orderly transportation and timely placement of greenhouse poles through the coordinated control of pole-separation, pole-transmission and pole-casting components and discharging ramps. The device has an independent modular design, in that it is complete, can realize the automatic feeding operation separately and can be upgraded to the traditional insertion frame model. By establishing a regression model with the qualified rate of pole casting as the evaluation index and adopting a three-factor three-level experimental design, the optimal parameter combinations were obtained. The structure and working parameters were optimized to verify operational performance, thereby providing a reference for the realization of the automatic feeding of small-arched greenhouses.

2. Materials and Methods

2.1. Design of Automatic Feeding Device

The crucial component that keeps the automatic trellis-insertion machine for tiny arches running continuously is the automatic feeding device for the trellis poles. The apparatus comprises pole feeding, pole separation, pole transfer, discharge ramps and a control system, among other components. In Figure 1, the trellis pole is placed in the storage hopper; the trellis pole separating component separates the stacked trellis poles; the trellis pole slides down to the trellis pole-transfer component; the synchronous belt lifts the trellis poles to the row of poles on the inclined plate; the casting pole component rotates 180°; and the trellis poles are thrown from the row of poles on the inclined plate into the insertion device to be picked up at the material position. Concurrently, another groove hole is moved to the lower part of the trellis poles to be cast, thus completing the process of separating and casting a trellis pole.

2.2. Shed Pole-Separation Mechanism Design

As shown in Figure 2, the shed rod-separation mechanism is an essential part of the automatic feeding system that enables single separation of shed rods. It consists of a seated slide bearing, revolving long shaft, separating rod and an ordinary DC motor. The trellis pole extrudes the distributed round bar under the influence of gravity as the round bar rotates under the motor’s drive. Each time the distributed round bar rotates, one trellis pole is removed from the feeding groove, allowing separation of the trellis poles by a single pole.

The motor drives the material-separating rod, and its efficiency directly affects operation of the shed rod-separation mechanism. To guarantee that the material-separating rod can be turned on quickly and continues to spin steadily and strongly, the torque of the DC motor must fulfill the following specifications:

$$\beta ={\displaystyle \frac{\Delta \omega }{\Delta t}}$$

(1)

$$J={\displaystyle \frac{1}{2}}m{r}^2$$

(2)

$$M=J\beta ={\displaystyle \frac{m{r}^2\omega }{2t}}$$

(3)

where β is the angular acceleration (rad/s²); J denotes the moment of inertia (kg·m²); M is the torque (N·m); ω is the angular speed (rad/s); t denotes the time of change of angular velocity (s); m is the split round bar weight (kg); and r is the split round bar radius (m).

The separating round bar was constructed of nylon, had 80 mm diameter and weighed 4.9 kg overall, to minimize the weight of the separating bar and friction between the separating bar and shed rod. When the separating bar’s initial rotational speed is 60 rpm, the torque required by the DC motor is 23.8 N-m when Formulas (1)–(3) are combined. As a result, a DC motor with a 50 K speed reduction ratio and a speed reducer was chosen.

2.3. Shed Pole-Conveyor Design

As shown in Figure 3, the trellis pole-conveying mechanism comprises bearings, an active shaft, a driven shaft, a synchronous wheel and a synchronous belt with block. To guarantee a timely supply of trellis pole materials, the synchronous belt with block was utilized to transfer the trellis poles separated by the trellis pole-separating mechanism to the discharging inclined plate.

A synchronous belt transmission was selected because of its consistent transmission ratio, smoothness and resistance to slipping, to increase the smoothness and efficiency of shed pole transmission [27]. To minimize pole damage during transmission, the synchronous belt was fitted with blocks based on the intended distances.

The following equation should be satisfied by the synchronous belt power.

$$P_d=K_{A}P$$

(4)

$$p={\displaystyle \frac{F_{\mathrm{t}}v}{\eta }}$$

(5)

$$F_{\mathrm{t}}=m_{\mathrm{t}}\mathrm{a}$$

(6)

where P_d represents the power of the synchronous belt (kW), and K_A denotes the operating condition factor. Operational stability is ensured by setting K_A to 1.3; P is the power transfer via the synchronous belt (kW); F_t denotes the maximum synchronous belt traction (N); ν denotes the synchronous belt speed (m/s); m_t is the weight with everything loaded (kg); and a is the acceleration of the synchronous belt (m/s²).

Based on the relative positions of the shed pole-separating part and the discharging inclined plate, the shed pole’s stroke on the synchronous belt is 460 mm; upward lifting time is 3 s; acceleration time is 0.5 s; synchronous belt running speed is 0.15 m/s; and its acceleration is 0.3 m/s².

Based on Equations (4)–(6), P_d is 105 × 10⁻³ kW. As a result, a tooth synchronous belt of type T10, trapezoidal, with 32 teeth and a 43 mm bandwidth, was chosen.

2.4. Pitching Rod Mechanism Design

As shown in Figure 4, the pitching mechanism primarily consists of a stepping motor, fixed support, pitching rod long shaft, fixed ring and pick-up ring. When the stepper driver is operating, it receives the signal from the control system, rotates the pickup ring, steps the stepping motor to a specific angle, removes the pole from the pickup ramps and throws it into a position where it needs to be bent and inserted into the frame.

The shed rods create a collision force throughout the conveying and separating operations, which is mostly influenced by height and speed during separation [28,29]. When the ring is rotated to a predetermined position, the shed poles fall onto the trellis pole support plate under the force of gravity and wait for the rotary device to continue rotating to carry out the insertion operation. This process of rotating and conveying involves the pitching ring conveying the trellis poles to obtain the initial speed. The speed is along the direction of rotation of the pitching ring, and the magnitude of the speed is the same as the linear speed of the ring. The natural falling trajectory may be affected if the speed is too high, because it will result in a larger collision force with the shed pole-blocking member ahead. A mass point in the conveying process, as the shed pole approaches separation from the pitching rod ring, is considered as the subject of kinematic analysis, as illustrated in Figure 5.

The plane right-angle coordinate system is established by the shed rod and pitching rod mechanism-planting point for the origin; the tangential direction is the positive x-axis direction and pointing to the pitching rod snap center in the positive y-axis direction. The linear velocity of the shed rod is equal to the absolute velocity of the pitching rod snap ring at point O, assuming that the shed rod is detached from the pitching rod snap ring at origin O for parabolic motion and disconnected from point O at that instant. Without considering the energy loss, the collision stress between the trellis pole and trellis pole-blocking member is:

$$F=m\left({\displaystyle \frac{1}{2}}{V}^2+gh\right)$$

(7)

where F is the collision stress between the trellis pole and the trellis pole-blocking member (N); m is the average quality of a single pole (kg); V is the instantaneous velocity of the shed pole at point E(m/s); g is the gravitational acceleration (m/s²); h denotes the vertical distance between the drop point of the trellis pole and origin O (mm).

Based on Equation (7), V and h play a major role in determining the collision stress between the trellis pole and obstructing plate. Because the falling pole height of the trellis pole is limited by the overall design height of the machine, the conveying speed has a greater effect on the collision stress of the trellis pole.

The automatic feeding device frame was parallel to the ground, and the rotational speed of the rod-throwing mechanism was divided into three levels of rod-throwing tests, and each group test was repeated three times, obtaining the average value to investigate the effect of the rotational speed of the rod-throwing mechanism on the qualified rate of rod throwing. The effect of the pitching rod mechanism on the pitching rod pass rate curve at various speeds is shown in Figure 6.

According to Figure 6, the qualified rate of the pitching rod increases as the speed of the pitching rod mechanism increases and then gradually decreases after reaching its peak. This is because an excessively low speed cannot ensure a timely supply of materials, affecting the subsequent insertion of the normal operation of the frame mechanism. Moreover, a larger speed increases the collision force, making it more likely that the shed rod is not a normal fall rod, which affects the subsequent insertion action of the frame mechanism. The pitching rod mechanism is 19 r/min when the qualified rate of pitching rod is high.

2.5. Automatic Feeding Device Control System Design

The design consisted of proximity sensors, photoelectric sensors (Siemens S7-200CPU224, manufactured by Siemens AG, headquartered in Munich, Germany), the feeding system and the control system of the automatic feeding device for small-arch functions. In Figure 7, the overall control flow is displayed.

2.6. Test Material

The tests were conducted at the Nanjing Agricultural Mechanization Research Institute of the Ministry of Agriculture and Rural Affairs, Nanjing, China. Trellis poles (6 mm in diameter and 1600 mm in length) comprised the test materials. Among the measurement tools were a 5 m tape measure, 300 mm steel ruler and tachometer (HT-5500, manufactured by Ono Sokki Co., Ltd., headquartered in Yokohama, Japan. Maximum pressure: 1 kN; measuring range: 6–600 r/min; precision: ±0.02%). The test stand was constructed, as shown in Figure 8.

2.7. Assessment Metrics and Quantification Techniques for Automated Feeding Apparatuses

The evaluation indices of the automatic feeding device comprised qualified rate of rod casting and rate of rod leakage, which ran parallel to the ground. Each test group was run three times to calculate the average value.

$$Y_1={\displaystyle \frac{N_1}{N}}\times 100\%$$

(8)

$$Y_2={\displaystyle \frac{N_2}{N}}\times 100\%$$

(9)

where Y₁ denotes the pitch pass rate; N₁ is the number of shed poles that are successfully pitched; N₂ denotes the number of shedless pole drops; N is the total number of poles; and Y₂ denotes the leakage rate.

3. Results

3.1. Box–Behnken Center Combination Test and Analysis

In actual operations, the device is installed on the top of the hanging small-arched greenhouse insertion machine along with the planting mechanism to complete the planting operation of the poles. Hence, the device is an important indicator of the normal operation of the entire machine for planting poles at the right time, with the placement of poles exceding the rate of the evaluation of the device being an indicator. Due to the nonlinear effects of pickup snap ring speed (A), shed pole drop height (B) and pickup snap ring spacing (C) on the passing rate of pole casting. A three-factor three-level Box–Behnken response surface method was used to investigate the influence of these factors on the qualification rate. The experimental design was performed using Design-Expert 13 software [30]. Seventeen groups of tests were conducted. The coded levels of the test factors are listed in

Table 1. Coding table of test factor levels.

Code Value	Reclaiming Ring’s Spinning Speed (A) (r/min)	Trellis Pole’s Falling Pole Height (B) (mm)	Reclaiming Ring’s Spacing (C) (mm)
−1	15	400	1250
0	20	450	1350
1	25	500	1450

. Through the single-factor analysis of the rod-throwing mechanism speed on the qualified rate of rod throwing, we obtained a speed of 19 r/min, the highest qualified rate of rod throwing. Thus, the speed of the reclaiming ring was set at 15–25 r/min. According to the overall dimensions of the machine, the height of the storage hopper was 450 mm; the discharging device was located in the hopper in front of the discharge device, and the height of the shed rod with the height of the storage hopper was approximately the same as that of the entire machine and was compact. Therefore, the shed rod height was determined to be 400–500 mm. As the length of the pole is 1600 mm, the spacing between the pick-up rings is too large or too small, leading to interference with the stability of the pole gripping. Considering the installation of the machine, the pick-up ring spacing was positioned at 1250–1450 mm.

A bench prototype was used to conduct the automatic pole-dropping test, and the passing rates of the pitching of the sheds were recorded. The stepping motor controls the speed of the card ring recovery; the test stand height completes the height of the shed pole drop; and the position of the card ring may be adjusted to modify the distance in-between.

Table 2. Test program and results.

Test No.	Reclaiming Ring’s Spinning Speed (r/min)	Trellis Pole’s Falling Pole Height (mm)	Reclaiming Ring’s Spacing (mm)	Pitching Pass Rate (%)
1	25	400	1350	93
2	20	500	1450	87
3	20	450	1350	96
4	15	500	1350	85
5	15	450	1450	86
6	20	500	1250	82
7	25	450	1450	82
8	20	450	1350	92
9	20	450	1350	95
10	15	400	1350	84
11	25	500	1350	85
12	20	400	1250	91
13	25	450	1250	92
14	20	400	1450	84
15	20	450	1350	92
16	15	450	1250	82
17	20	450	1350	91

presents the test results.

Using Design-Expert 13 software, a regression equation was fitted to the experimental results in Table 2 to produce a quadratic polynomial equation for the shed pass rate, as shown in Equation (10). The p < 0.05 and the coefficient of determination, R2 = 0.9398, for the pitching pass rate model indicates a high correlation between measured and predicted values. The p > 0.05 in the loss-of-fit test indicates no loss of fit, suggesting that the regression equation is well fitted. The results are shown in

Table 3. Analysis of variance for pitching pass rates.

Source of Error	Sum of Squares	df	Mean Square Sum	F-Value	p-Value	Significance
Model	344.42	9	38.27	12.15	0.0017	*
A	28.13	1	28.13	8.93	0.0203	*
B	21.12	1	21.12	6.71	0.0360	*
C	8.00	1	8.00	2.54	0.1550
AB	20.25	1	20.25	6.43	0.0389	*
AC	49.00	1	49.00	15.56	0.0056	*
BC	36.00	1	36.00	11.43	0.0117	*
A2	50.84	1	50.84	16.14	0.0051	*
B2	37.27	1	37.27	11.83	0.0108	*
C2	75.16	1	75.16	23.86	0.0018	*
Residuals	22.05	7	3.15
Misfit term	3.25	3	1.08	0.2305	0.8710
Error	18.80	4	4.70
R2	0.9398

* means significant.

.

$$K=93.2+1.88\mathrm{A}-1.62B-C-2.25AB-3.5AC+3BC-3.48A^2-2.98B^2-4.22C^2$$

(10)

DesignExpert 13 was used to create the response surface curves (Figure 9). The response surfaces were used to investigate the effects of the interaction between the other two test factors, A, B or C, when one of them was at the 0 level.

The reclaiming ring spacing is located in Figure 9, which displays the response surface curves of the interaction between the reclaiming ring’s spinning speed and the trellis pole’s falling height in relation to the pitching pass rate at the center level (1350 mm). The qualified rate of pitching increases and then decreases with an increase in the height of the shed pole drop when the speed of the reclaimer ring is fixed at a certain level. Nevertheless, 400–440 mm was determined to be the optimal range because a 400–440 mm drop in shed pole height had the least impact on the qualified rate of pitching. The qualified rate of pitching grew with the speed of the reclaimer ring when the height of the shed pole drop was fixed at a given level, and thereafter tended to decrease. Consequently, 21–25 r/min was the optimal planting speed range.

Figure 10 displays the response surface curves of the pitching pass rate interaction between the reclamation ring’s spacing and spinning speed, with the trellis pole’s falling pole height at the center level (450 mm). The qualifying rate of rod casting shows a trend of rising and then reducing with an increase in the reclaiming ring’s spacing when the ring’s speed is fixed at a specific level. The optimal range for reclaiming ring spacing is 1330–1400 mm. The qualifying rate of the rod casting exhibits an increased trend with an increase in the reclamation ring’s speed when the gap between them is fixed at a particular level. Consequently, the recovering ring’s optimal speed range is 21~25 r/min.

Figure 11 displays the response surface curves of the pitching pass rate interaction between the reclaiming ring’s spacing and the trellis pole’s falling pole height. The reclaiming ring’s spinning speed is at the center level (20 r/min). The optimal range for the height of the shed pole falling rod is 400–450 mm. When the pick-up ring spacing is established at a given level, the qualified rate of the pitching rod with an increase in the height of the shed pole falling rod initially displays a rising and then decreasing pattern. The qualifying rate of the scaffolding with an increase in the pick-up card ring spacing first exhibits a rising and then dropping trend, with the rate of decline being faster than the rise, when the height of the shed pole falling rod is set at a given level. Consequently, 1250–1380 mm is the optimal range for the pick-up card ring’s pitch.

3.2. Parameter Optimization

The best combination of operating parameters for improving the pitching pass rate is obtained by optimizing the experimental results of the indoor bench work using the optimization module of Design-Expert 13. According to the effect of the interaction between the two factors of pickup ring spacing speed, trellis pole drop height and pickup ring spacing on the passing rate of pole casting, the value intervals of pickup ring speed, trellis pole drop height and pickup ring spacing were determined. The constraints of Equation (11) were established to achieve the highest pitching pass rate, as follows:

$$\left\{\begin{array}{c}\max {\mathrm{y}}_1(A,B,C)\\ \left\{\begin{array}{c}21 \mathrm{r}/\min <A<25 r/\min \\ 400 \mathrm{mm}<B<440 \mathrm{mm}\\ 1330 \mathrm{mm}<C<1380 \mathrm{mm}\end{array}\right.\end{array}\right.$$

(11)

The software analysis revealed the optimal combination of working parameters as follows: reclaiming ring spinning speed of 23.94 r/min; trellis pole falling pole height of 408.799 mm, reclaiming ring spacing of 1350 mm, resulting in pitching pass rate of 95.36%.

To confirm the model’s findings, the bench device was modified using the ideal parameter combination, and indoor operation tests were repeated. Based on the actual working condition requirements of the automatic feeding device, optimized theoretical values were rounded, thereby setting the test conditions to a reclaiming ring spinning speed of 24 r/min, trellis pole falling pole height of 409 mm and reclaiming ring spacing of 1350 mm. To obtain average values, the test results were sampled three times, and the effects of random errors were eliminated. The results are substantially compatible with the measured pitching pass rate, which averaged 94.23%. The relative error between the optimized and test values was 1.13%. Consequently, it was confirmed that the ideal parameter combination was reliable.

3.3. Field Tests

The experiment was conducted in the cantaloupe test area of Hami City, Xinjiang, and the optimal combination of factors was used to produce the average result after three trials. The operating distance of the hanging small-arched insertion machine was 100 m. The test site’s soil type was sandy. There was 2.5% moisture in the soil. The forward tractor speed was calibrated to 1.2 km/h prior to the test, and the navigation was set up correctly. The field test site is shown in Figure 12.

In the field test, the reclaiming ring’s spinning speed was 24 r/min; the falling pole height of the trellis pole was 410 mm; and the spacing of the reclaiming ring was 1350 mm (

Table 4. Results of the field experiment.

Test No.	Total Number of Poles	Number of Shed Poles Successfully Pitched	Number of Shed-Less Pole Drops	Pitching Pass Rate (%)	Leakage Rate (%)
1	101	95	6	94.06	5.94
2	100	94	6	94	6
3	102	100	2	98.04	1.96

). Using Equations (8) and (9), the pitching pass rate was calculated as 95.37 ± 1.89%; the pole leakage rate was 4.63 ± 1.89%; and the measurement process did not require trellis pole repositioning, and the overall operating conditions were good.

4. Discussion

An automatic feeding system for trellis poles was invented in response to the issue of small-arch greenhouse insertion machines still having to manually cast poles. Compared with the toggle-wheel-type pole feeding mechanism, this device can ensure single-pole separation, orderly transportation and timely placement of poles through the synergistic control of the pole separation, pole conveyor and pole dropping assemblies and discharging ramps The device has an independent modular design and separate configuration of the power supply. The entire device is independent and complete, capable of realizing the automatic feeding operation alone and upgradable to the traditional insertion of the frame model.

The goal was to increase the operational efficiency of small-arch greenhouses, and a mathematical regression model for the pitching pass rate was established. Pitching pass rates of 95.36% and 95.37% were achieved in field tests. The well-established findings on the pitching pass rate of the trellis are consistent with the relative error of 0.01% between the optimal value of the regression equation in the field and the actual test value. Accuracy and dependability are demonstrated by the three-way quadratic equation that includes the reclaiming ring spacing, trellis pole falling pole height and reclaiming ring spinning speed.

In practice, this device is installed on top of the hanging small-arched greenhouse-inserting machine, cooperating with the planting mechanism to complete the planting operation of the poles. This device solves the leakage of poles due to the untimely casting of poles during manual operation and improves the operation quality and efficiency of the small-arched greenhouse automatic frame insertion and machine mulching. The automatic feeding device solves the problems of low production efficiency and high labor costs without depending on manual labor for feeding poles.

When working in the field, the shed poles can be pre-positioned on the pole-rowing ramps of the device to minimize the error of untimely pole placement because of failures of the pole-separating and conveying devices. However, the field operation environment is complex, and the ground is uneven, easily causing vehicle body bumps. Excessive bumps not only affect the automatic pole-casting device to take polesbut also cause the planting mechanism to take poles, impacting the success rate; therefore, the field needs to be flattened before operation. The small-arch greenhouse automatic planting, insertion and mulching machine can realize the entire process operation consisting of shed pole separation, timely pole placement, shed pole bending, planting and mulching, with a high degree of automation, only necessitating high synchronization and coordination of the various parts of the machine tool. Therefore, the cooperation and synchronization performance of the automatic feeder device and other machine tool devices should be improved. The deficiencies observed thus far will be studied further and addressed in future experiments.

5. Conclusions

In this study, the design of the small-arched trellis-insertion machine automatic feeding device can realize automatic single separation, orderly delivery and timely placement of small-arched trellis poles. It can effectively reduce labor costs, improve small-arched trellis building and cover film operation efficiency, which is conducive to the industrialization of the development of facility agriculture.

To provide automatic single separation, orderly conveyance and timely installation of small-arch trellis poles, an automatic feeding system was devised for trellis inserters. The qualifying rate of pitching through the test stand was measured using a three-factor, three-level Box–Behnken response surface test. The test results demonstrated that the qualified pitching rate was primarily influenced by the reclaiming ring speed, shed pole height and spacing. The ideal ranges were as follows: for reclaiming ring speed, 20–25 rpm; shed pole height, 400–450 mm; and reclaiming ring spacing, 1330–1380 mm.

The results and the real needs for the planting machinery’s working conditions were analyzed using Design-Expert 13 software, whereby optimized theoretical values were rounded to obtain the optimal parameter combination: reclaiming ring spinning speed of 23.94 r/min, trellis pole falling pole height of 408.799 mm and reclaiming ring spacing of 1350 mm, resulting in a pitching pass rate of 95.36%. Based on the optimal parameter combination, the automatic feeding mechanism was retested. The average value of the measured pitching pass rate was 94.23%, and the relative error between the test value and theoretically optimized value was 1.13%. The accuracy of the model is high, verifying the reliability of the optimal parameter combination.

The field-casting test results indicate a reclaiming ring spinning speed of 24 r/min, trellis pole falling pole height of 410 mm, reclaiming ring spacing of 1350 mm, qualified pole-casting rate of 95.37% and leakage rate of 4.63%. The measurement process did not find any instances of the shed pole being heavy, indicating that the automatic feeding device had a strong anti-interference ability. The theoretical optimization value of the error was 0.01%. Therefore, the findings of this study can serve as a basis for the design and optimization of automatic feeding devices.