Analysis and Test of Clamp Conveying Type Residual Film Recycling and Film Impurity Separation Mechanism

Abstract

Aiming at the problem of the difficult separation of film in the process of farmland residual film recovery, a clamping conveying residual film recovery device was designed and studied. The device was mainly composed of a clamp plate, clamp plate conveying chain, chain wheel drive shaft, and the residual film conveying chain and frame. Firstly, the structure and working principle of the device are introduced. The tensile properties of the residual film are investigated to determine the relationship between the average clamping force, the height of the clamp plate, the spacing of the clamp plate, and the rotational speed of the sprocket. Then, the mechanical properties of the residual film are discussed. The influence weight of each factor on the film impurity separation rate is summarized by single factor tests. The regression equation between the factors and film impurity separation rate is established. The results of the variance analysis of regression equation show that the film impurity separation rate was 93.70% at 1.08 m/s conveying speed of clamp plate, with 12 clamp plates, and 7 residual film conveyor chains. Taking the maximum value of the film impurity separation rate (η) as the objective using MATLAB, the optimal result was in good agreement with the regression equation. In addition, the field test results show that the film impurity separation rate was 92.35%. Compared with the theoretical analysis results, the relative error was 1.35%. The research results provide a theoretical reference for the design of related devices.

1. Introduction

Mulch film technology can improve crop yields [1], control weed growth, and preserve soil moisture [2]. It is one of the technical guarantees of food security in arid areas in arid and semi-arid regions [3]. Although mulch film technology has resulted in obvious economic benefits, it has also brought serious environmental pollution. According to the reports, white pollution has affected sustainable agricultural development [4,5,6,7,8,9,10]. The mulch film exists in the field for 8–10 years, resulting in 187.5 kg per hectare of residual film and a 17% reduction in production [11,12,13,14,15,16]. The literature shows that the pickup rate is larger when the soil is looser and the moisture content and viscosity are lower. To solve the difficult problem of film impurity separation, a mechanical recycling technique is utilized as an effective means.

At present, many recycling machines of residual film have been designed, which are mainly teeth type [17], finger-chain type [18], and roller type [19] film–soil separating devices of the residual film recycling machine. Parish [20] developed an automatic machine to roll up plastic mulch, while maintaining constant torque on the mulch spool regardless of the tractor speed or effective spool diameter. Kimball [21] developed a mobile apparatus to process plastic mulch, and the mulch was caught by a plastic mulch lifting apparatus which pulled the plastic mulch upward from the field and disposed of it with a plastic mulch receiving bin. For example, Rocca et al. developed a mulch film with a chain conveyor [22]. The machine was conveyed to the film roil through the chain conveyor. According to the working principle of the film recycling machine, the film recycling machine consists of a chain screen, finger-chain and arc tooth rolling, etc. The chain-screen mulching machine scoops up the film–impurity mixture through a digging shovel, passing it through the shaking of the chain gear mechanism. The mixture is separated through the surface of the screen. The problem of separation between film and impurity is further solved [23]. When the finger chain mulch film recycling machine works, the finger picks up the remaining film around the pitch line of the lower sprocket. When it passes the upper sprocket, the finger stretches, and the mulch film falls into the collecting box owing to the gravity. The film impurity separation rate is 93.8% [24]. Therefore, when recycling machines work, the complex working conditions in the field and many impurities on the surface are important factors which effect recycling efficiency [25,26,27]. At the same time, the parts of recycling machines regarding residual film are difficult to work in the conditions. In addition, film impurity separation is also an important problem for recycling residual film. The recycling residual film includes many impurities and is difficult to reuse [28,29,30,31].

To solve the problem, this paper designs a clamp conveying residual film recycling device, which obtains the residual film with different shapes and strengths by clamping and picking. Compared with other recycling methods of residual film, the clamping method shows the stronger picking capability and higher recycling rate of residual film. In addition, the separation mechanism of film impurity is analyzed, and the factors affecting the film impurity separation rate are discussed. Moreover, the central composite design theory is employed to establish the quadratic model of the film impurity separation rate. The results are analyzed using Design Expert 8.0.6 and are optimized using MATLAB to determine the reasonable operating parameters of the device. Comparing the actual results and statistical analysis results, the relative error is 1.5%. The field tests are conducted to verify the theoretical analysis and the feasibility of the device. This research provides theoretical support for simplifying the structure of similar residual film collectors, providing reasonable structural parameters under actual working conditions, enhancing the film recycling rate, and reducing the cost of film recycling.

2. Materials and Methods

2.1. Overall Structure and Working Principle of the Machine

The machine consists of a clamp plate, straw crushing device, chain wheel, rack, clamp plate conveying chain, chain wheel transmission shaft, roller, and residual film conveying chain.

The gearbox is installed in the front of the straw chopping and residual film recycling machine and is connected to the power output shaft of tractor. The power of the gearbox drives the straw chopping device and the residual film recycling machine. Meanwhile, the clamp plate of the residual film recycling machine contacts with the residual film conveying chain and moves backwards at the same time. The working process of the mechanism is: the straw crushing device crushes the cotton stalks on surface and then transports them to the rear side of implement. The residual film is stripped from the surface by starting tooth. Then, the stripped residual film is transported to the residual film conveying chain using clamping plate. With the movement of the clamping plate and the residual film conveying chain, the residual film is transported along the residual film conveying chain. The film is conveyed along the film conveying chain to the inclined top direction. At this time, the soil under the film drops from the spacing between the conveying chains, while the impurities slip down as the mulch film is clamped tightly, thus realizing the separation of residual film and impurities. At last, the residual film is conveyed to the position above the film box and drops into the film box under the function of film removing mechanism.

2.2. Overall Structure and Working Principle

The clamp conveying type residual film collector includes roller, rack, clamp plate conveying chain, residual film conveying chain wheel, etc., as shown in Figure 1 [32].

2.3. Mechanical Analysis of Film Impurity Separation

During the process of residual film collection, the cotton stalk is removed using the straw chopping mechanism, and the surface of the mulch film is covered by impurities including cotton branches or leaves, soil, and short straws. The film shovel of the residual film collector driven by the drive system lifts the mulch film. The rotating clamp plate scrapes the film to the conveying chain. The clamp plate contacts the conveying chain and clamps the residual film. The clamp plate conveys the film along the conveying chain into the recycling box. To improve the stability of the residual film, the residual film is clamped between the clamping plate and the residual film conveyor chain. It is necessary to consider the clamping force required for the residual film mixed in the debris to be pulled out. As shown in Figure 2, we established a coordinate system with the tight side contact point of the clamp plate and the residual film conveying chain as the center O and the surface of the vertical film conveying chain as the reference.

The end part of the residual film is regarded as the force point. Meanwhile, the mass of the film at this point is neglected. The kinetic analysis was conducted. We obtained the following expression (1):

$$F_{\mathrm{f}}\ge F_{\mathrm{L}}\cos \alpha$$

(1)

$$F_{\mathrm{N}}+F_{\mathrm{L}}\sin \alpha =F_{\mathrm{N}}^{\text{'}}$$

(2)

$$F_{\mathrm{f}}=\mu F_{\mathrm{N}}$$

(3)

where

$F_{\mathrm{L}}$ = the pulling force exerted on the residual film (N);

$F_{\mathrm{N}}$ = the pressure of the clamp plate on the conveying chain (N);

${F^{\prime }}_{\mathrm{N}}$ = the reaction force of the film conveying chain on the clamp plate (N);

$F_{\mathrm{f}}$ = the friction of the residual film (N);

μ = the dynamic friction coefficient (0.1);

α = the included angle between the residual film and the tight side of the conveying chain (°).

The residual film is scraped by clamp plate to the conveying chain and is conveyed. Here, the other clamping plate contacts to the surface of residual film within t time (t ≤ 0.125 s). Therefore, the α can be calculated with following Equation (4):

$$\mathsf{\alpha }=\arctan \frac{l}{\mathrm{L}-\mathrm{R}wt}$$

(4)

According to Equations (1)–(4), when the residual film is conveyed, the clamping force is calculated using the following Equation (5):

$$\overline{F_{\mathrm{N}}} \ge \frac{F_{\mathrm{L}}\cos \left(\arctan \frac{l}{\mathrm{L}-\mathrm{R}wt}\right)}{\mu }$$

(5)

The average pulling force of the residual film on a single conveying chain can be calculated using tensile test of residual film [33]. The sample of residual film (working time for 5–6 months in cotton fields) was utilized. The main component of residual film was polyethylene with a thickness of 0.008 mm. Elongation is one of the main indexes of tensile properties of residual film. According to the displacement increment and the initial line spacing of the sample, the elongation is as follows:

$${\delta }_b=\frac{b-b_0}{b_0}$$

(6)

where

${\delta }_b$ = the elongation (%);

b = the fracture line spacing (mm);

$b_0$ = the initial line spacing (mm).

The samples of residual film were post-processed before starting test. According to Part 1 of tensile test of plastics in GB/T1040.1-2006, the tensile test of residual film was carried out using electronic universal testing machine (HY-0580, Shanghai Hengyi Precision Instruments Co., Ltd., Shanghai, China). The results are shown in

Table 1. The results of the tensile properties of plastic film.

Number	Original Length (mm)	Maximum Pulling Force (n)	Tensile Strength (mpa)	Maximum Deformation (mm)	Elongation (%)
1	150	3.184	0.00159	135.36	135
2	150	3.703	0.00185	127.72	128
3	150	3.010	0.00151	102.57	103
4	150	3.317	0.00166	109.16	110
5	150	2.747	0.00138	132.02	132
6	150	2.532	0.00126	143.41	143
7	150	3.302	0.00165	113.94	114
8	150	2.565	0.00129	164.77	165
average	150	3.045	0.00153	129.55	130
medium	150	3.097	0.00155	122.98	123
StdDev		0.135	0.70000	13.59	14
CV%		4.400	4.40000	10.50	10.5

.

The tensile test of the residual film shows that the average pulling force of the clamped residual film on a single film conveying chain is about 3 N. Residual film with a smaller damage degree may be easily broken if it is conveyed too quickly on the conveying chain. The residual film scraped by clamp plate may be mixed with the impurities and conveyed into the recycling box together. However, this has less impact on the fragmented residual films. The reasons are that these films can be pulled out from the impurities when the clamping force is larger.

The residual film is recovered in time because the film-lift tooth is blocked by the impurities included in residual film. As shown in Equation (5), the clamping force can be increased when the bracket of the clamp conveying device is adjusted (Figure 1). In addition, when the clamping force remains constant, the pulling force of the residual film increases with the increase in the angular velocity of the clamp conveying chain wheel. At the same time, the pulling force of the residual film is close to the average pulling force of the residual film.

The analysis of the average clamping force of the residual film shows that the rotation speed of the clamp plate conveying chain wheel has significant effect on film impurity separation. Therefore, the rotation speed or the conveying speed of the residual film should not be too high.

2.4. Analysis of Residual Film Conveying Chains

Figure 3 shows the top view of the clamp conveying type residual film recycling device. The arrangement of the film conveying chains is also presented.

When the clamp conveying device is working, the residual branches, leaves, and straws clamp plate may be scraped to the conveying chain. The overcrowded arrangement of conveying chains reduce the spacing between two adjacent conveying chains, making it hard for the long straws and other impurities to drop through the spacing and be scraped by the clamp plates to the recycling box. As a result, the impurity rate will be too high, which will influence the recycling efficiency and reuse of residual films.

The distribution of residual film existing in the 0–300 mm plough layer in cotton fields is relatively concentrated. According to the reports [34,35,36], the residual film existing in the 0–300 mm plough layer in cotton fields accounts for more than 85% of the total residual film in cotton fields, and the many residual films are fragmented. When the residual film conveying chain has a small number, the small residual film with a flaked shape will drop from the conveying chains, resulting in a lower recycling rate. According to the above analysis, the design is reasonable with 6–10 film conveying chains.

2.5. Analysis of Clamp Plate

As shown in Figure 4B, the clamp plate and the residual film conveying chain are arranged in a symmetric transverse manner. With the increasing number of residual film conveying chains, the soil and stones scraped by the clamp plate are easily dropped from the residual film conveying rack. The impurities increase in the residual film collecting box because the plant branches and leaves are not easily cleaned out. With the decreasing number of residual film conveying chains, the residual film is easy to lose, and recycling rate does not meet the requirement. In addition, it is difficult to meet the reliability requirement of motion kinematics when the machine is produced. As shown in Figure 4A, the clamp plate and the residual film conveying chains are arranged in a laterally symmetrical manner. When the machine works, the residual film is scraped to the residual film conveying chains by the film shovel. At the same time, the residual film pressed on the residual film conveying chain using clamp plate is upward transport. The residual film in bottom is tensioned, and the impurities on the surface of the residual film slide down along the inclined surface of the residual film. The approach is reliable for transmission. Comparing the characteristics of two arrangements, the arrangement in Figure 4A is adapted.

Figure 3 shows the arrangement and spacing of clamp plates. The number of clamp plates and the spacing between two adjacent clamp plates affect the working efficiency of the device. When the spacing is too large and the working speed of the recycling machine is fast, the residual film cannot be scraped to the residual film conveying chain in time. Therefore, the residual film accumulates at the film lifting shovel. With the increasing amounts of residual film at the film lifting shovel, the residual film and impurities are scraped to the conveying chain by the clamping plate again. The impurities will enter the residual film recovery box with the residual film because they are not easy to separate from the residual film. As the clamp plates increase, the tension on the conveying chains of the clamp plate increases, affecting the reliability transmission of the conveying chains of clamp plate. During work in field, the conveying chains of clamp plate with variable speed causes the dynamic load. The pulling force of conveying chains of clamp plate caused by dynamic load can be expressed using the following formula [37]:

$$F_{\mathrm{L}}={\mathrm{a}}_{\mathrm{c}}\left(n{m}_1+2m_2\right)$$

(7)

The forward acceleration of conveying chains of clamp plate is calculated using formula:

$${\mathrm{a}}_{\mathrm{c}}=\frac{dv}{dt}=\frac{{\mathrm{D}}_1}{2}{w}_1\sin \beta \frac{d\beta }{dt}=\frac{{\mathrm{D}}_1}{2}{w}_1^2\sin \beta$$

(8)

$$\beta =\frac{180°}{Z_1}$$

(9)

According to the Equations (8) and (9), the pulling force of conveying chains of clamp plate is calculated using (10) formula:

$$F_{\mathrm{L}}=\frac{{\mathrm{D}}_1}{2}\left(nm+2m_2\right)w_1^2\sin \frac{180°}{Z_1}$$

(10)

where

$F_{\mathrm{L}}$ = the pulling force of the conveying chains of clamp plate (N);

$m_1$ = the mass of single conveying chain of clamp plate (kg);

$m_2$ = the mass of the clamp plate (kg);

$a_{\mathrm{c}}$ = the forward acceleration of conveying chains of clamp plate (m/s²);

n = the number of conveying chains of clamp plate;

${\mathrm{D}}_1$ = the pitch diameter of the conveying chain wheel of clamp plate (mm);

$w_1$ = the angular velocity of the driving chain wheel of clamp plate (rad/s);

$Z_1$ = the number of tooth of the conveying chain wheel of clamp plate.

According to Equation (10), when other parameters are constant, the pulling force exerted on the conveying chains of clamp plate increases with the increasing number of clamp plates, which effects the reliability transmission of conveying chains of clamp plate. Therefore, the number of clamp plates should not be too high. Combining the Equations (7)–(10), the number of clamp plates is 9–13, and the speed of the conveying chain of clamp plate is 1.05−1.26 m/s.

3. Test design and Result Analysis

3.1. Test Condition

As shown in Figure 5, the test location is the Eighth Division of Xinjiang Production and Construction Corps, China. The test conditions were as follows. The soil moisture content was 18.3%, and the thickness of residual film was 0.008 mm. Meanwhile, the test area 50 m in length and 12 m in width was utilized. The working width of the recycling device was 1.5 m. In addition, the ground was flat, and the soil hardness was moderate. The residual film existed in the field for about 5–6 months. Most of the mulch film existed on the surface of the cotton fields. The residual film is employed after the crops are harvested every year, and its tensile strength was high. The testing machine was the straw chopping and residual film combined machine designed by the research group. The clamp conveying type residual recycling device was installed on the straw chopping and residual film combined machine, which was powered by a Foton Lovol tractor (M800-D, Foton Lovl Heavy Machinery Co., Ltd., Beijing, China).

3.2. Test Index

The separation rate of film impurity was used as the test index in this test and was calculated using the following method. The residual film and impurities in the recycling box were weighed after each test to calculate the separation rate of film impurity. The formula is as follows:

$$\eta =\frac{m_p}{m_p+m_q}\times 100\%$$

(11)

where

m_p = the mass of the residual film in the recycling box (kg);

m_q = the mass of the impurities in the recycling box (kg).

3.3. Test Factors

The mechanism analysis on the film impurity separation indicates that three test factors (the conveying speed of the clamp plate, the number of clamp plates, and the number of film conveying chains) influenced the film impurity separation rate. In addition, the conveying speed of the clamp plate ranged from 1.05 m/s to 1.26 m/s. The number of clamp plates and film conveying chains were 9–13 (n₁) and 6–10 (n₂), respectively.

3.4. Test Process and Results

There are many non-linear factors influencing the film impurity separation rate during residual film recycling. Therefore, this test employed the response surface method to establish the model [38,39,40,41] and assumed that the film impurity separation rate Y has a functional relationship with the clamp conveying speed X₁ (m/s), the number of clamp plates X₂, and the number of film conveying chains X₃. Based on the response surface method, the test code of three factors and five levels was established. The coding table of factors and the test results are shown in

Table 2. Factor and level of test.

		Factor
		X1	X2	X3
Level	1.682	1.26	13	10
	1	1.22	12	9
	0	1.16	11	8
	−1	1.09	10	7
	−1.682	1.05	9	6

and

Table 3. Test results.

Number	Level of Factor			Index
	X1	X2	X3	Y
1	−1	−1	−1	87.5
2	1	−1	−1	82.4
3	−1	1	−1	93.2
4	1	1	−1	89.2
5	−1	−1	1	82.4
6	1	−1	1	81.3
7	−1	1	1	82.2
8	1	1	1	83.9
9	−1.682	0	0	85.2
10	1.682	0	0	81.6
11	0	−1.682	0	82.5
12	0	1.682	0	91.2
13	0	0	−1.682	94.6
14	0	0	1.682	79.2
15	0	0	0	84.8
16	0	0	0	82.3
17	0	0	0	85.1
18	0	0	0	83.6
19	0	0	0	81.7
20	0	0	0	84.9

, respectively [42,43,44,45,46]. X₁ is the conveying speed of the clamp plate (m/s). X₂ is the number of clamp plates. X₃ is the number of film conveying chains. Y is the film impurity separation rate (%).

3.5. Result Analysis

The data in Table 2 were analyzed using Design Expert 8.0.6 software, and the regression equation and the variance analysis are as follows:

$$\mathrm{Y}=-1.07{\mathrm{X}}_1+2.16{\mathrm{X}}_2-3.54{\mathrm{X}}_3+0.49{\mathrm{X}}_1{\mathrm{X}}_2+1.21{\mathrm{X}}_1{\mathrm{X}}_3-1.26{\mathrm{X}}_2{\mathrm{X}}_3-0.24{\mathrm{X}}_1^2+0.98{\mathrm{X}}_2^2+{\mathrm{X}}_3^2$$

(12)

Based on the misfit value and F value in

Table 4. Variance analysis.

Sources	Sum of Squares	$D_f$	Mean Square	F Value	p-Value	Significant
Model	305.55	9	33.95	14.11	0.0001	**
X1	15.51	1	15.51	6.45	0.0294	*
X2	63.86	1	63.86	26.54	0.0004	**
X3	171.53	1	171.53	71.29	<0.0001	**
X1X2	1.90	1	1.90	0.79	0.3949
X1X3	11.76	1	11.76	4.89	0.0515
X2X3	12.75	1	12.75	5.30	0.0441	*
${\mathrm{X}}_2^1$	0.82	1	0.82	0.34	0.5714
${\mathrm{X}}_2^2$	13.86	1	13.86	5.76	0.0373	*
${\mathrm{X}}_2^3$	14.36	1	14.36	5.97	0.0346	*
Residual	24.06	10	2.41
Lack of fit	13.49	5	2.70	1.28	0.3980
Pure error	10.57	5	2.11
Cor total	329.61	19

Note: p ≤ 0.01 means highly significant, **; p ≤ 0.05 means significant, *.

, the regression equation fits well with the test model. The influence of the number of clamp plates and residual film conveying chains is highly significant. In addition, the conveying speed of the clamp plate is significant. The interaction between the conveying speed of the clamp plate and the number of residual film conveying chains is significant. The interaction between the number of clamp plates and the number of residual film conveying chains is also significant. However, the interaction between the conveying speed of the clamp plate and the number of clamp plates is not significant. The quadratic term of the number of clamp plates and the number of residual film conveying chains is significant. However, the quadratic term of the clamp conveying speed of the clamp plate is not significant. As can be seen from Figure 6B,C, the stronger interaction between the conveying speed of the clamp plate and the number of residual film conveying chains is observed. The stronger interaction between the number of clamp plates and the number of residual film conveying chains is also found. As shown in Figure 6A, the interaction between the conveying speed of the clamp plate and the number of clamp plates is weak.

As shown in Figure 6A, the film impurity separation rate increases with the increase in clamp plates. The reason is that the increasing number of clamping plates improves the pickup capacity of the residual film. The residual film can be scraped by the film-lift tooth in time to avoid the secondary movement of the accumulated residual film and impurities by the film-lift tooth. As the conveying speed of the clamp plate increases, the film impurity separation rate decreases. The reason is that the increased conveying speed of residual film increases the speed at which the maximum pulling force of the residual film reaches the average pulling force. The residual film is quickly pulled off, and the broken residual film and impurities are picked up by the film-lift tooth again. As can be seen from Figure 6B, the film impurity separation rate reduces with the increased number of residual film conveying chains, owing to the reduced spacing between the two adjacent conveyor chains. The short straws, branches, and leaves do not drop from the spacing between conveying chains and are eventually transported to the recycling box. In addition, when the size of mulch films is large, the spacing between the mulch film and the clamp plate decreases with the increase in residual film conveying chains. Therefore, small impurities do not drop from the spacing, increasing the impurities in the recycling box. Figure 6C indicates that the film impurity separation rate increases with the increase in the clamp plates.

The above results are consistent with the results of variance analysis. In addition, the relationship between the film impurity separation rate and the factors is depicted in Figure 7 [47,48,49,50].

3.6. Parameters Optimization

Film impurity separation is a key part of the recycling process of residual film, and the film impurity separation rate is one of the important indexes to assess the recycling effect. In the scope of testing, the higher film impurity separation rate indicates a better recycling effect. Taking the maximum value of film impurity separation rate (η) as the objective, the optimal combination of the conveying speed of residual film and the number of clamping plates and conveying chains is decided using MATLAB [51,52,53,54]. The final optimal results are as follows: the film impurity separation rate is 93.70% under the conditions (1.08 m/s conveying speed of the clamp plate, with 12 clamp plates, and 7 residual film conveying chains).

3.7. Model Verification

To verify the above optimized results, a field experiment was carried out with the parameters of the optimized factors. According to the original test method and test conditions, the tests were achieved and were repeated three times. The test results are shown in

Table 5. Test results.

Test Number	Membrane Impurity Separation Rate/%	Mean/%	Relative Error
1	92.54	92.35	1.44%
2	91.89
3	92.62

, and the averaged film impurity separation rate is 92.35%. Comparing the actual results and statistical analysis results, the relative error is 1.5%. Therefore, the selected model is appropriate in this study and well met the requirements of the operation.

4. Conclusions and Future Perspectives

In this paper, a new method of recycling residual film is proposed. Compared with other ways for recycling residual film, the method shows a higher film impurity separation rate. In addition, the integrity of the residual film is better. The mechanism of the film impurity separation was analyzed, and the correctness of the theoretical analysis and the feasibility of the device were discussed using tests.

(1) Based on the tensile test results of the residual film, the mechanical analysis of the residual film was carried out. Combining the planting mode of cotton and other factors, the relationship between the maximum pulling force and the speed of the conveying chain was discussed. In addition, the relationship between the number of conveying chains and the number of clamping plates was analyzed.

(2) Analysis on the film impurity separation mechanism of the clamp conveying type residual film recycling device shows that the film impurity separation rate was affected by three major factors, i.e., the conveying speed of the clamp plate, and the number of clamp plates and residual film conveying chains. The influence of test factors on the film impurity separation rate was studied using the model interaction and response surface. The results show that the effect of the clamp conveying speed on the film impurity separation rate is significant, and the effect of the number of clamp plates and residual film conveying chains on the film impurity separation rate is highly significant.

(3) The software of MATLAB was used to optimize the results. The operating parameters of the key parts of the clamp conveying type residual film recycling device were determined. When the film impurity separation rate was 92.35%, the conveying speed of clamp plate was 1.08m/s, and the number of clamp plates and residual film conveying chains were 12 and 7, respectively. Comparing the actual results and statistical analysis results, the relative error was 1.5%.

(4) During the recycling process of the residual film, the working efficiency of the device is low, and the dust dropping from the device is larger, which needs to be solved in future investigations.