Design and experiment on scoop hole-wheel precision seed-metering device for rice

doi:10.3969/j.issn.1004-1524.2021.04.19

Acta Agriculturae Zhejiangensis ›› 2021, Vol. 33 ›› Issue (4): 739-752.DOI: 10.3969/j.issn.1004-1524.2021.04.19

• Biosystems Engineering • Previous Articles Next Articles

Design and experiment on scoop hole-wheel precision seed-metering device for rice

LIU Jun¹(), ZHU Dequan1¹^,²^,^*(), YU Congyang¹, XUE Kang¹, ZHANG Shun¹, LIAO Juan¹

1. School of Engineering, Anhui Agricultural University, Hefei 230036, China
2. Anhui Province Engineering Laboratory of Intelligent Agricultural Machinery Equipment, Hefei 230036, China

Received:2020-09-03 Online:2021-04-25 Published:2021-04-25
Contact: ZHU Dequan1

Abstract

Abstract:

In order to solve the problems of poor seed filling performance and low precision in high-speed seeding process, a scoop-hole-wheel precision seed-metering device for rice was designed. A scoop was used to disturb the seed layer to increase the fluidity between rice seeds and enhance the performance of seed filling. The basic structure and working principle of the seed metering device were expounded, the structural parameters of key components such as seeding wheel, scoop, hole, seed protection guard were determined, and the mechanical model of the seed-metering process was established. The numerical simulation experiments based on discrete element method were carried out by using Gangyou 898 as the research object. Taking rotation speed and hole inclination of seeding wheel as the experimental factors, single-factor experiments, comparative experiments and orthogonal rotation combined experiments with two factors and five level were carried out. The regression model between experimental factors and seeding performance index was established. The influence regulation of experimental factors on the seeding performance was analyzed by the response surface method, and the best combination of parameters was determined through the multi-objective optimization method. The optimization results showed that the seeding performance of seed-metering device was the best when rotation speed of the seeding wheel is 25.94 r·min^-1 and hole inclination of the seeding wheel was 34.75°, and seeding qualified rate, replay rate and missing rate were 87.55%, 9.79%, and 2.66%, respectively. In order to verify the reliability of the simulation results and the adaptability of the seed-metering device, rice seeds of three varieties of Fengliangyou 3948, Gangyou 898 and Gangyou 3551 were used as test materials to perform the bench tests and field tests. The test results showed that the results of bench tests were basically consistent with the simulation results, and seeding qualified rates of Fengliangyou 3948, Gangyou 898 and Gangyou 3551 were 84.40%, 84.53% and 83.74%, respectively, their sowing qualified rates of field test were 81.34%, 82.13% and 80.67%, respectively. Sowing performance of three varieties rice seeds all met the requirements for precision sowing of rice. This research results could provide reference for structure optimization and performance improvement of the scoop hole-wheel precision seed-metering device for rice.

Key words: rice, mechanization, sowing, seeding performance, seed-metering device, scoop hole-wheel, numerical simulation

CLC Number:

S223.2 ⁺3

LIU Jun, ZHU Dequan1, YU Congyang, XUE Kang, ZHANG Shun, LIAO Juan. Design and experiment on scoop hole-wheel precision seed-metering device for rice[J]. Acta Agriculturae Zhejiangensis, 2021, 33(4): 739-752.

Figures/Tables 21

Fig.1 Diagram of structure and working principle of seed-metering device a, Isometric view of seed-metering device; b, Working principle and seed-metering process. 1, Flange; 2, Seeding shaft; 3, Seeding wheel; 4, Limit plate; 5, Shield shell; 6, Cleaning brush; 7, Shaped hole; 8, Protection guard; 9, Resist brush; 10, Scoop.

Fig.2 Schematic diagram of scoop structure a, Partial sectional view of seeding wheel; b, Schematic diagram of scoop. 1, Scoop; 2, Shaped hole; 3, Seeding wheel. w1 was the width of scoop, mm; t1 was the thickness of scoop, mm; l1 was the length of scoop, mm.

Table 1 Seed size and sphericity of three varieties of rice

品种(尺寸等级) Variety (Size level)	平均长度 Average length/mm	平均宽度 Average width/mm	平均厚度 Average thickness/mm	种子球度 Seed sphericity/%
丰两优3948(大)Fengliangyou3948(Large)	9.63	2.52	2.08	38.38
冈优898(中) Gangyou898(Medium)	8.29	2.96	2.10	44.89
冈优3551(小) Gangyou3551(Small)	7.77	3.14	2.16	48.25

Table 2 Pose probability of rice seed in filling hole %

品种 Variety	平躺 Lying down	侧卧 Side lying	竖立 Erect
丰两优3948	48.98	40.43	10.59
Fengliangyou 3948
冈优898	50.59	36.59	12.82
Gangyou 898
冈优3551	50.88	34.98	14.14
Gangyou 3551

Fig.3 Structure of protection guard a, Curved seed protection belt; b, Curved seed protection belt with notch; c,Curved seed protection belt with felted hair in large notch. H was the width of seed protection belt, mm; H1 was the width of notch, mm.3种护种板厚度H均为32 mm,槽口宽度H1长度应满足式(9)要求。

Table 3 Test results

护种板类型 Type of protection guard	合格率 Qualified rate/%	重播率 Replay rate/%	漏播率 Missing rate/%	穴距变异系数 Variation coefficient of hole distance
弧形护种板Curved seed protection guard	76.54	16.93	6.53	15.57
开有槽口的弧形护种板Curved seed protection guard with small notch	82.27	12.80	4.93	9.60
槽口内装毡毛的弧形护种板	84.00	11.33	4.67	8.57
Curved seed protection guard with felted hair in large notch

Fig.4 Stress analysis of rice seed in seed-filling process Fr was centrifugal force of seed, N; F1 was support force of scoop to seed, N; F2 was pushing force among seed groups, N; G was gravity of seed, N; f1 was friction force between inner surface of scoop and seed, N; f2 was friction force in seed groups, N; α was the angle between direction of gravity and x axis, (°); β was the angle between direction of F1 and x axis, (°).

Table 4 Material properties

项目 Item	剪切模量 Shear modulus/Pa	泊松比 Poisson’s ratio	密度 Density/ (kg·m^-3)
种子Seed	1.15×10⁷	0.30	1 163
不锈钢Stainless steel	7.00×10¹⁰	0.28	7 800
塑料Plastic	1.77×10⁶	0.50	1 180
毡毛Felt	1.00×10⁸	0.40	1 150

Fig.5 Rice model a, Triaxial size; b, EDEM model. l was length of rice seeds, mm; w was width of rice seeds, mm; t was thickness of rice seeds, mm.

Table 5 Coefficients of materials

项目 Item	恢复系数 Coefficient of restitution	静摩擦系数 Coefficient of static friction	动摩擦系数 Coefficient of rolling friction
种子-种子Seed-seed	0.30	0.56	0.01
种子-塑料	0.50	0.50	0.01
Seed-plastic
种子-不锈钢	0.60	0.30	0.01
Seed-stainless steel
种子-毡毛	0.45	0.61	0.02
Seed-felt

Fig.6 EDEM simulation of seed motion of seed-metering process a. Process of seed-filling; b. Process of seed-metering.

Fig.7 Relationship between evaluation index and rotating speed of seeding wheel

Fig.8 Relationship between evaluation index and hole inclination of seeding wheel

Fig.9 Seeding performance of the two seed-metering devices at different speeds a, Qualified rate of the two seed-metering devices at different speeds; b, Missing rate of the two seed-metering devices at different speeds.

Table 6 Test factors coding and levels setting

编码 Code	X₁:排种轮转速 Rotating speed of seeding wheel/(r·min^-1)	X₂:型孔倾角 Hole inclination of seeding wheel/(°)
1.414	37.50	50.00
1	33.84	45.60
0	25.00	35.00
-1	16.16	24.40
-1.414	12.50	20.00

Table 7 Results of simulation experiments

试验号 No.	排种轮转速 Rotating speed of seeding wheel	型孔倾角 Hole inclination of seeding wheel	Y₁:合格率 Qualified rate/%	Y₂:重播率 Replay rate/%	Y₃:漏播率 Missing rate/%
1	1	1	81.60	7.60	10.80
2	1	-1	83.60	12.80	3.60
3	-1	1	82.00	12.40	5.60
4	-1	-1	81.20	16.00	2.80
5	1.414	0	82.00	9.20	8.80
6	-1.414	0	78.40	19.20	2.40
7	0	1.414	83.60	6.40	10.00
8	0	-1.414	82.00	12.80	5.20
9	0	0	86.00	9.60	4.40
10	0	0	87.20	10.00	2.80
11	0	0	88.40	9.60	2.00
12	0	0	89.20	9.20	1.60
13	0	0	88.40	8.80	2.80
14	0	0	86.80	11.20	2.00
15	0	0	86.80	10.80	2.40
16	0	0	87.20	10.80	2.00

Table 8 Variance analysis of regression equations

差异来源 Source of variation	合格率Qualified rate
差异来源 Source of variation	平方和 Sum of squares	自由度 Degree of freedom	F	P	平方和 Sum of squares	自由度 Degree of freedom	F	P	平方和 Sum of squares	自由度 Degree of freedom	F	P
模型Model	145.10	5	25.60	**	139.72	5	27.87	**	125.67	5	26.63	**
X₁	6.29	1	5.54	*	61.28	1	61.13	**	28.32	1	30.01	**
X₂	0.14	1	0.12		39.83	1	39.73	**	35.23	1	37.33	**
X₁X₂	1.96	1	1.73		0.64	1	0.64		4.84	1	5.13	*
$X 1 2$	97.99	1	86.54	**	37.85	1	37.75	**	14.04	1	14.88	**
$X 2 2$	38.71	1	34.14	**	0.13	1	0.12		43.24	1	45.82	**
残差	11.34	10			10.03	10			9.44	10
Residual
失拟	3.42	3	1.01	0.444 4	4.91	3	2.24	0.171 6	4.08	3	1.77	0.239 3
Lack of fit
误差	7.92	7			5.12	7			5.36	7
Pure error
总和Total	156.44	15			149.75	15			135.11	15

Table 8 Variance analysis of regression equations

差异来源 Source of variation	合格率Qualified rate
差异来源 Source of variation	平方和 Sum of squares	自由度 Degree of freedom	F	P	平方和 Sum of squares	自由度 Degree of freedom	F	P	平方和 Sum of squares	自由度 Degree of freedom	F	P
模型Model	145.10	5	25.60	**	139.72	5	27.87	**	125.67	5	26.63	**
X₁	6.29	1	5.54	*	61.28	1	61.13	**	28.32	1	30.01	**
X₂	0.14	1	0.12		39.83	1	39.73	**	35.23	1	37.33	**
X₁X₂	1.96	1	1.73		0.64	1	0.64		4.84	1	5.13	*
$X 1 2$	97.99	1	86.54	**	37.85	1	37.75	**	14.04	1	14.88	**
$X 2 2$	38.71	1	34.14	**	0.13	1	0.12		43.24	1	45.82	**
残差	11.34	10			10.03	10			9.44	10
Residual
失拟	3.42	3	1.01	0.444 4	4.91	3	2.24	0.171 6	4.08	3	1.77	0.239 3
Lack of fit
误差	7.92	7			5.12	7			5.36	7
Pure error
总和Total	156.44	15			149.75	15			135.11	15

Fig.10 Response surface of rotation speed and hole inclination of seeding wheel on seeding performance index

Fig.11 Diagram of bench test 1, Seed bed belt; 2, Oil pump; 3, Fixed bracket; 4, Control console; 5, Lighting installation; 6, Motor; 7, Seed-metering device.

Table 9 Results of bench tests

品种 Variety	合格率 Qualified rate/%	重播率 Replay rate/%	漏播率 Missing rate/%	穴距 Hill distance/mm	穴距变异系数 Variation coefficient of hill distance/%
丰两优3948	84.40	8.27	7.33	205.32	7.98
Fengliangyou 3948
冈优898	84.53	10.67	4.80	206.34	8.32
Gangyou 898
冈优3551	83.74	12.13	4.13	208.84	9.22
Gangyou 3551

Table 10 Results of field test

品种 Variety	合格率 Qualified rate/%	重播率 Replay rate/%	漏播率 Missing rate/%	穴距 Hill distance/mm	穴距变异系数 Variation coefficient of hill distance/%
丰两优3948	81.34	10.93	7.73	209.57	15.36
Fengliangyou 3948
冈优898	82.13	11.87	6.00	209.12	16.48
Gangyou 898
冈优3551	80.67	13.73	5.60	212.73	18.36
Gangyou3551

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Design and experiment on scoop hole-wheel precision seed-metering device for rice

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