Search

To solve the problems of low removal rate and incomplete separation for the current longitudinal-axial-flow combined harvester in the case of harvesting rice and wheat, a segmented longitudinal-axial-flow threshing device was designed in this paper. The threshing device mainly comprised a tapered threshing roller, a concave sieve with adjustable threshing strength, a 360° separation device and an electric control system for operating parameters. Through the single factor tests, the optimal switching states of the concave sieve with adjustable threshing strength for rice and wheat threshing was obtained respectively. In order to find out the influence rule of the working parameters of the device on the threshing effects and the optimal parameter combination, the multi-objective optimization tests were carried out. The rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the separation gap of concave sieve and the feeding rate were selected as the influence factors and the crushing rate, impurity rate and loss rate were selected as the test indexes. The test results showed that the significant sequence of influence of threshing parameters on the crushing rate was the rotational speed of roller, the threshing gap of concave sieve, the angle of deflector, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on impurity rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on loss rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. Through multi-objective parameter optimization analysis, the optimal working parameters combination for wheat threshing were determined that the rotational speed of roller was 905 r/min, the angle of deflector was 69°, the threshing gap of concave sieve was 18 mm, the separation gap of concave sieve was 19 mm and the feeding rate was 4 kg/s. The field verification tests were carried out using the optimal working parameters combination. The results indicated that the crushing rate was reduced from 1.46% to 1.00%, the impurity rate was reduced from 1.85% to 1.43% and the loss rate was reduced from 1.72% to 1.20% compared with the conventional longitudinal-axial-flow threshing device. All the relative errors between the measured values and the optimized values were less than 5%, the working indicators met the requirements of relevant national standards. The device effectively solved the problems of high crushing rate, unclean threshing and incomplete separation, the research results can provide reference for the structural improvement and operation parameters optimization of the threshing device of longitudinal-axial-flow combined harvester. [ABSTRACT FROM AUTHOR]

As a large agricultural country, there are still more than 40% of people in China engaging in agricultural production activities. In recent years, the soil erosion and desertification have been in serious state, and the arable land has decreased year by year, which means that it is very necessary to develop agricultural technology to improve crop yield per unit area. Therefore, in recent years, China has vigorously developed agricultural greenhouse cultivation which has characteristics of high input, high technology and high yield. Agricultural greenhouse cultivation is an important part of China’s agricultural production. In 2014, the area of greenhouse in China was up to 4.109 million hm2. With the promotion of precision agriculture, the technology of modern agricultural greenhouse cultivation is developing towards precision. Precision fertilization is one of the important parts of precision agriculture operation system. Due to that the structure of modern agricultural greenhouse is closed, and the planting area is limited in China, the large agricultural machinery cannot be applied to greenhouse operations, leading to that the mechanization level in greenhouse production is lower than other developed countries in the world. At present, the fertilization in greenhouse in China is still mainly relying on manpower. Because of the increasing labor cost and decreasing yield in greenhouse production, the profits of greenhouse is reduced. In the pursuit of more profit, people’s requirements of precision fertilization in greenhouse are increasingly urgent. This paper mainly introduced a small, precise and practical fertilizing machine. This machine was mainly used in greenhouse and it was intelligent and automatic. The fertilization machine used ARM9 S3C2440 microprocessor as the core of circuit control module. It was equipped with a fertilizer level monitoring alarm device, and would alarm automatically when the fertilizer level was less than 15 cm, so that the staff could add fertilizer in time. The machine used the Geneva mechanism as fertilizer metering mechanism. By controlling the pulse frequency of the stepping motor, the amount of fertilization could be controlled so as to achieve quantitative precision fertilization. The three-dimensional model of the fertilization machine was built by the SolidWorks. The intensity check was performed for its main parts of the force with simulation. All those verified that the structure could meet the requirements of hardness and intensity. The fertilization effect was simulated by the EDEM (enhanced discrete element method), a general CAE (computer-aided engineering) software applied to the discrete element method. In the simulation, the speed of the sheave was set to 10 r/min, the output time step was 0.05 s, and the total simulation time was 5 s. It was found that there weren't flying particles during the process of simulation, which showed that the selected rotational speed of the sheave and the parameter of the simulation time step were reasonable. The sheave grooves in the process of simulation were almost filled with the fertilizer particles, which proved that the device could get a good effect of fertilization and the parameter of the sheave was reasonable. The brush structure in the fertilization device could effectively get rid of the extra fertilizer particles and supplement fertilizer particles for other incompletely filled groove in order to make sure every groove could discharge a certain amount of fertilizer. The simulation results showed that the fertilization device could discharge the fertilizer particles evenly, stably and continuously. By properly controlling the rotation speed of the drive shaft, the fertilization machine could achieve the goal of precise fertilization. The results show that maximum error of fertilizer test actual value and the theoretical value is 2.42%, less than 3% under four kinds rotational speed (5, 10, 15, 20 r/min). Therefore, the machine designed in this paper could greatly improve the automation level for greenhouse production and reduce the labor intensity of fertilization in greenhouse. It has broad applicability and popularity in our facility greenhouse production. [ABSTRACT FROM AUTHOR]

Astragalus smicus, also known as Chinese milk vetch, Zi yunying and so on, is one of the main winter green manure crops in paddy fields of central and southern China, it has the advantages of reducing fertilizer input, improving soil fertility, increasing crop yield and quality, and protecting ecological environment, and has strong nitrogen fixation ability and high utilization efficiency. In recent years, the production machinery of Astragalus smicus has been developed and applied rapidly in terms of capacity and utilization efficiency, but its development still lags behind. Ditching and sowing are important links in the production of Astragalus smicus. The yield of Astragalus smicus is largely determined by the quality of sowing, and ditching operation can make Astragalus smicus grow well in low-humid field with poor drainage or sandy soil with poor fertilizer and water retention. Astragalus smicus is often used as green manure in paddy field, but high stubble retention, large amount of straw, insufficient in sowing height of existing other sowing equipments, working parts easily clogged, etc., bring difficulties for mechanized production of Astragalus smicus. In order to solve the influence of machine-harvested rice stubble on mechanized production of Astragalus smicus, aiming at the problems of low quality and low production efficiency in independent ditching and sowing links at present, a Astragalus smicus ditching and sowing machine which suitable for machine-harvested rice stubble field was developed. A height adjustable sowing device was designed, by which the sowing components could be lifted to a proper position according to the residual straw situation in the field. The special seed-metering wheel and quantitative evenly-sowed device for Astragalus smicus were developed to achieve precision sowing and improve the sowing uniformity. The structure and working parameters of the double-disk ditching components were determined. The variation coefficients of ditching width and depth determined by field experiments were less than 6%, which met the drainage requirements of Astragalus smicus growth process. The multiple factor experiments and regression analysis of the test data were carried out by Design-expert software, the results showed that forward speed of machine, rotation speed of seed-metering wheel, seed-uniforming cylinder diameter significantly affected the sowing performance, the results of variance analysis showed that the rotation speed of seed-metering wheel had the greatest influence on the emergence rate and coefficient of variation of sowing uniformity, while the forward speed of machine had the least influence on the emergence rate and coefficient of variation of seed-metering quantity consistency, regarding the coefficient of variation of sowing uniformity, the most influential factor was seed-uniforming cylinder diameter, and the minimum impact factor was the rotation speed of seed-metering wheel, the optimal factor parameters combination which affected the sowing quality of Astragalus smicus ditching and sowing machine was as follows: forward speed of machine was 4.6 km/h, rotation speed of seed-metering wheel was 44 r/min, seed-uniforming cylinder diameter was 6 mm. Verified by field experiments, the Astragalus smicus emergence rate was 95.87%, quantity consistency was 12.7%, coefficient of variation of sowing uniformity was 8.07% in the condition of optimal parameter combination, the relative error was below 3% compared with optimal values predicted by the model. Compared with the existing sowing methods of Astragalus smicus, working efficiency of the designed ditching and sowing machine was 1 hm2/h, which was superior to the artificial sowding working efficiency of 0.1 to 0.125 hm2/h, the hand-shaking working efficiency of 0.2 to 0.3 hm2/h and the motorized sowing working efficiency of 0.5 to 0. 8 hm2/h, and was lower than the UAV sowing working efficiency of 3 to 4 hm2/h. In addition, the coefficient of variation of sowing uniformity and the combination type of ditching and sowing machine were also significantly superior to that of other methods. The Astragalus smicus ditching and sowing machine developed in the paper integrated ditching and sowing links in one operation, the working efficiency was greatly improved, the research provided a new method for Astragalus smicus ditching and sowing machine for machine-harvested rice stubble field. [ABSTRACT FROM AUTHOR]

Small deep-cultivators with light weight and simple structure are urgently needed to satisfy the requirements of deep cultivating in hilly regions. Development of a low power-consumption rotavator is a prerequisite for the lightweight of a small deep-cultivator. In this paper, in order to reduce the power consumption of the rotavator for a small vertical-shaft deep-cultivator, a multi-helical rotavator was proposed. The multi-helical rotavator consisted of a vertical-shaft rotavator head and 3 discontinuous multi-helical cutters that are unevenly distributed along the circumference of the head. The discontinuous multi-helical cutter consisted of a cutter-shaft and 3 discontinuous helical cutter edges that are evenly distributed along the axis of the cutter-shaft. The rotavator head had a diameter of 250 mm and the rotavator had a design tillage depth of 30 cm. The cutter-shaft length was 0.35 m and the helical angle of the helical cutter edge was 53º. Based on the motion analysis of the multi-helical rotavator, the motion path and its parameters model were established. The structure and operating parameters of the discontinuous multi-helical cutter and the rotavator were designed and analysed. Then the three-dimensional models of the discontinuous multi-helical cutter and the rotavator were established for simulation analysis. Based on the SPH (smoothed particle hydrodynamics) algorithm, the motion of soil particles, cutting resistance and power consumption were simulated and analysed during the operation of the discontinuous helical cutter and the traditional vertical-shaft orthogonal cutter in ANSYS LS-DYNA. In addition, an actual multi-helical rotavator was manufactured and its tillage effect and power consumption were tested. The simulation results showed that, comparing with the traditional vertical-shaft orthogonal cutter, the performance of the discontinuous helical cutter was significantly improved. 1) The discontinuous multi-helical cutter could greatly stir the upper soil particles, and the displacement of the upper soil particles was obviously increased during the cultivation process. At the same time, the lower soil particles were only slightly disturbed, and the displacement of the lower soil particles was significantly reduced. 2) The cutting resistance of the designed discontinuous helical cutter decreased by an average of 37.5%. Besides, the fluctuation range of cutting resistance decreased by an average of 60.6%, which could reduce the rotavator vibration and make the small deep-cultivator to work more stably and more reliable. 3) The total energy consumption of the designed discontinuous helical cutter was reduced by 58.7% and the average power consumption was reduced by 47.6%, which could reduce the weight of the small deep-cultivator under the same power consumption conditions. The test results showed that the actual power consumption of the designed multi-helical rotavator was 2.86 kW, which was 11.28% higher than the simulation value of 2.57 kW. The simulated power consumption value was close to the test value, which verifies the validity of the simulation results. At the same time, the average tillage depth of the designed multi-helical rotavator was 28.7 cm with a stability coefficient of 94.64% and the average soil pulverizing rate is 76.02%. Therefore, the designed multi-helical rotavator had better crushing and throwing ability than the traditional vertical-shaft orthogonal cutter, and could improve the soil subsoiling effect while meeting the requirement of the tillage depth. The reduction in cutting resistance and the decrease in cutting resistance fluctuation could also reduce the power consumption and vibration of small deep-cultivators. [ABSTRACT FROM AUTHOR]

The purpose of conservation tillage is to protect soil structure, conserve water and maintain soil moisture. No-tillage sowing is the core of the development of conservation tillage technology. Focusing on many problems unsolved of no-tillage planter, such as the non-adjustable space between seeds, seeding only on a single line, high probability to be adhered and blocked, and poor adaptability, this paper proposes a new advanced design of no-tillage hill seeder. The hill seeder is connected to tractor with the suspension frame, and it can complete a seeding of three rows by three planting units at every run. Each planting unit is mainly composed of land wheel, seed metering device, fertilizer apparatus and 45° inclined inserted digging implement. The digging implement is mainly composed of parallel four-bar mechanism, slider-crank mechanism and cam mechanism. The power transmission route is as follows: the land wheel rotates to obtain power, drives the seed metering device and fertilizer apparatus, and then through the chain drive to the parallel four-bar mechanism and slider-crank mechanism, completing penetration reciprocating seeding and fertilizer, while driving cam mechanism controls the opening and closing movement of the duckbill. The design of no-tillage hill seeder has the following features. Firstly, to efficiently avoid the problems of soil blocking, soil attaching, difficulties in opening and so on, this new hill seeder would perform an insertion into soil at a 45°angle with a refined plugging unit. Secondly, this design has added configurable sprocket gears to solve the problem that the existing seeders could not adjust the distance between seeds. Thirdly, the design of the parallel four-bar mechanism makes the insertion of the crank blocks more smoothly with the unified seeding depths, at the same time the synchronization of seeding and fertilizer could be achieved. Additionally, all the parameters of the machine (e.g. rows spacing, plants spacing, seeding depth, fertilizer depth) are adjustable which could bring better adaptability. Field experiment was done in the experiment base by inclined inserted no-tillage hill seeder prototype. The results showed that seeding depth and fertilizer depth qualified rates were 90.52% and 91.23%, qualified rates of horizontal distance and vertical distance between seed and fertilizer were 95.71% and 91.65%, qualified rate of seeding uniformity is 92.13%, replay rate of seeding uniformity is 4.60% and leakage rate of seeding uniformity is 3.27%. The data are superior to the standard value, which is 85%, 15% and 8%. The research can provide a reference for the design of no tillage planter. [ABSTRACT FROM AUTHOR]

Garlic is one of the major cash crops in China, and it is mainly distributed in Shandong, Henan and Jiangsu Provinces. Single grain sowing is crucial for garlic planting, it needs to follow the agronomic requirements of root down and scaly bud upward, and therefore garlic planting mainly uses artificial means, but this method has shortcomings of strong labor intensity and low efficiency. Correspondingly, some developed countries like America and Korea have realized garlic planting mechanization in 1950-1960s, which have extensive arable land and indefinite requirement of garlic scaly bud direction when planting, and thus foreign garlic planting machinery is not suited to China’s national conditions. In recent years, the garlic planter is developed towards automation and intelligence. However, existing garlic planter is hard to distinguish the direction of garlic scaly bud, and it also has complex structure and low efficiency. The scaly bud direction distinguishing is a core technology of garlic planter, and it is also the most difficult technical operation. Therefore, how to ensure direction of the garlic seed scaly bud in the process of planting has been a key technical problem of garlic planter. According to present condition, a full-automatic extraction and release device of garlic seed box was designed based on garlic seed box method, and it can automatically track driving according to the travel speed of machine. The full-automatic extraction and release device of garlic seed box consists of drive system, conveying device, extraction and release device, speed encoder, photoelectric sensor and MCU (micro-controller unit) system. The drive system consists of stepper motor, sprocket and chain, and it has 2 parts, and one provides transmission power for the whole machine walking, and the other controls conveying device working. The conveying device consists of conveying belt, roll shaft and bearing housing, the conveying belt is transversely mounted on the frame through roll shaft and bearing housing, and its working state is controlled by MCU system. The conveying device mainly carries out transverse transportation of garlic seed boxes. The extraction and release device consists of steering wheel, central actuator, mechanical arm, auxiliary actuator and manipulator, among which the manipulator consists of U shape rotating frame, L shape mounting panel, distance controlling actuator, special shaped gear disk, connecting rod, connecting arm and claws, and it mainly realizes the functions of garlic seed boxes precision capture, smooth traffic and seamless release. The velocity measurement encoder is used for detecting unit movement speed, and provides speed messages to central actuator and distance controlling actuator. The photoelectric sensor is used to detect whether the garlic box is in place. The garlic seed box planting method reduces the damage of garlic seed and improves work efficiency, and solves the problem of the direction of garlic seed. This paper designed mechanical arm and manipulator, the mathematical model of each key component was established through the theory analysis, and thus the structure and working parameters of mechanical arm and manipulator were determined. At the same time, the influence rule of the speed of device marching on operation parameters of mechanical arm and manipulator was proved, and the influencing factors of the clearance of adjacent garlic seed boxes were specified. The test was carried out for testing the influence of the speed of device marching on the clearance of adjacent garlic seed boxes after they were released. The results showed that when the speed of marching is 0.90 km/h, and the speeds of central actuator, auxiliary actuator and distance controlling actuator are 26.04, 26.04, and 13.89 r/min, respectively, the clearance of adjacent garlic seed boxes is less, which is 5.6 mm, and the release effect is better. The machine has better stability and release effect, and work efficiency of device has been improved obviously. The research results can provide reference for realizing automation of garlic planting. [ABSTRACT FROM AUTHOR]