Study on Quality Improvement of Flue-cured Tobacco by Threshing and Pneumatic Separation

This study was conducted to further classify threshed strips, so as to broaden the usable range of raw material and facilitate the effective utilization of to- bacco resource. During the threshing and redwing process, various process param- eters including the rotating speeds of threshing drums of threshing machioe, draught fans and fling drums were scientifically and rationally set according to the actual quality of the raw material. According to the characteristic that strips with close in- herent quality have basically the same specific gravity and leaf thickness, the strips from each discharge hole were accurately evaluated, and classified, followed by redrying and packaging. The results showed that the threshing and separating pro- cedure could improve the separating effect and precision according to tobacco qual- ity, so as to satisfy the separation and classification requirements for tobacco.

Effect of mechanical threshing on damage and vigor of maize seed threshed at different moisture contents

Mechanical threshing used when preparing maize seeds for planting subjects seed to damage and reduces seed quality.The purpose of this study was to assess the effect of mechanical threshing on the quality of maize seed threshed at different moisture contents(MCs).Seeds of dent maize JK968 and flint maize DD2 were threshed at 12,15,18,21,and 24% MC.The damage degree was determined by iodine staining,and seed vigor was assessed by standard germination(SG),cold test germination(CTG),accelerated aging germination(AAG),seedling emergence rate,and seedling root and shoot length.The results showed that the damage percentage increased,and the seed vigor parameters decreased with increasing seed MC during threshing in both cultivars.For obtaining high seed quality,indicated by at least 90,85,and 80% of SG,AAG,and CTG,respectively,JK 968 and DD2 should be threshed at MC lower than 15 and 18%,respectively.Furthermore,the damage mainly occurred in the apical part of seeds,irrespective of the threshing MC in both cultivars.When the embryo was damaged,seedling emergence rates were significantly reduced with great influence on shoot length.Damage to the endosperm resulted in little effect on seedling performance.Flint maize DD2 was more tolerant to mechanical threshing than dent maize JK968.These results provided technical reference for the production and processing of high vigor maize seeds.

Influence of Shape and Size of Threshing Frame and Tobacco Grade on Leaf Strip Structure

This paper focused on the influence of the shape and size of threshing frames as well as the grades of tobacco leaves on the structure of threshed leaves.The testing tobacco leaves all came from the hilly ecological region of Nanling and belonged to burnt sweet,alcoholic sweet and scent category.The comprehensive evaluating value S was taken as the test index.Results showed that,without considering the influence of tobacco grade on leaf structure,the shapes of first-stage thresher five-link frames were all hexagons,and the combination with the sizes of 3.5,3.0,3.5,3.0,3.0 inches had the highest evaluating value S of 2.49.For tobacco grade C2FH,the shapes of first-stage thresher five-link frames were also hexagons,and the evaluating value S reached the highest value of 3.40 with sizes of 3.5,3.0,3.5,3.0,3.0 inches.Comprehensive analysis showed that:3.0 inch frame performed better in controlling the percentage of large-sized strips than 3.5 inch frame did;rhombic frames were better than hexagon frames in reducing the breakage rate of tobacco leaves;different shapes or sizes of nonadjacent two-link frames can help to improve the threshing quality.

Relation of Primitive Moisture Content and Energy Consumption on Soybean Pod Threshing

In this research, the effects of initial moisture content and needed impact energy on threshing of soybean pods were studied. An impact device was built based of pendulum mechanism. In the experiments, threshing percentage of soybean pod samples were measured at three initial moisture content levels of 16.25% and 35% w.b. and three energy levels of 173,284 and 446 mJ. The results of analysis of variance showed that moisture content and energy have significant effects on the threshing percentage. By increasing impact energy, amount of pod threshing increased. Also in all the energy levels, maximum threshing occurred at minimum moisture. Maximum threshing percentage was 83.4%, which was at 16% moisture content and 446 mJ levels, also minimum threshing percentage was 3.3% which was at 35% moisture content and 174 mJ levels. Soybean pod with higher moisture, contact between its edges of the pod was stronger than lower moisture, so more energy was needed to separate two edges at 35% moisture.

Occurrence Regularity and Life History of Cigarette Beetle Lasioderrma serricorne(Fabricius)in Tobacco Leaf Threshing and Redrying Workshop

[Objectives]The paper was to study the occurrence regularity and life history of cigarette beetle Lasioderrma serricorne(Fabricius)in tobacco leaf threshing and redrying workshop.[Methods]With the tobacco leaf threshing and redrying workshop as the survey site,the occurrence regularity of L.serricorne was investigated,and the life history table was inferred according to its biological characteristics.The temperature,humidity and duration of tobacco leaf threshing and redrying were simulated in the laboratory to study the survival rate of all states of L.serricorne in this environment.[Results]The lifecycle of L.serricorne in tobacco leaf threshing and redrying workshop was:the overwintering generation pupated in late February;the pupa began to emerge in early March,and reached its peak in late March.The first-generation eggs started hatching in late March,pupated in late May,emerged in early June,and reached the peak eclosion of the first-generation adults in mid-July.The second-generation eggs began to hatch in late July,pupated in mid-August,emerged in late August,and reached the peak eclosion of the second-generation adults in mid-September.The third-generation eggs began to hatch in mid-September;most of the larvae began to overwinter,some pupated in mid-November and survived the winter as pupae,and some pupae emerged to adults.The survival test results of different states of L.serricorne under simulated temperature,humidity and duration in the tobacco leaf threshing and redrying process showed that the mortality rates of eggs in simulated 1,2 and 3 conditions were about 51.22%,90.24% and 100%,and the mortalities of larvae in simulated 1,2 and 3 conditions were about 18.30%,81.25%and 100%,respectively.The mortalities of pupae in simulated 1,2 and 3 conditions were about 69.39%,100% and 100%,and the mortalities of adults in simulated 1,2 and 3 conditions were about 100%,100% and 100%,respectively.[Conclusions]L.serricorne of different states can be killed by appropriately raising the temperature during threshing and redrying.

Quality Evaluation of Threshing and Redrying Process Based on Analytic Hierarchy Process

Improving the stability of the homogenization process to achieve the homogeneity of tobacco products is one of important targets for the redrying industry.According to the specification for threshing and redrying process,a total of 14 indicators in three categories that affect the quality of the threshing and redrying process were selected.Using analytic hierarchy process,combined with expert experiences,a judgment matrix was constructed to conduct consistency test.The weights of indices in production were obtained.This will help in evaluating the actual production quality,finding the weak links of process and adjusting the parameters of the corresponding links in a targeted manner,thereby improving the quality of production process.

Analysis and performance test on dynamic seed corn threshing and conveying process with variable diameter and spacing

In order to further reduce the damage rate in threshing seed corn,a seed corn threshing testbed with variable diameter and spacing that can realize dynamic adjustment of parameters,such as feed quantity,rotating speed of the threshing device,threshing spacing of the threshing units,was designed in this research.The software of finite element analysis ANSYS Workbench was applied to do modal analysis on the threshing axis designed for variable diameter and spacing of seed corn.The first 8 orders of natural frequencies were distributed in 201.12-1640.20 Hz,with corresponding vibration amplitude in 5.86-27.04 mm,showing reasonable structural design of the threshing axis,which could realize effective seed corn threshing and conveying.Discrete element method was applied to do simulation analysis on the seed corn threshing and conveying process with variable diameter and spacing.Under the condition of different feed quantity,different rotating speed of the thresher,the moving speed of corn clusters and contact force among clusters were measured through simulation,and the working characteristics of the threshing testbed for low-damage and dynamic threshing and conveying of seed corn with variable diameter and spacing were revealed.Working performance test results of the testbed of seed corn with variable diameter and spacing showed that,when the rotating speed of the threshing axis was 190-290 r/min,feed quantity was 1.80-3.80 kg/s,the damage rate of seed corn was 0.32%-0.63%,threshing rate was 99.20%-99.82%,and content impurity rate was 4.23%-5.86%,the mass of threshed corn grains first increased and then decreased along the axial direction.The test verification process was in line with the simulation results;thus,the test results could satisfy the requirements in design and actual operation.

Design and experiment of corn low damage threshing device based on DEM

Kernel broken rate is an important index to evaluate the maize kernel direct harvesting quality.In view of the problem of the high kernel broken rate in the present maize harvester,a new threshing cylinder was designed in this study.This device utilized rasp bar to achieve low damaged maize ears threshing.In order to determine the structure and working parameters of threshing device,the“crop-crop”contact model and the“crop-mechanical”interaction system were established and analyzed based on the discrete element method first,and the mathematical expressions of the related kinematic response of maize kernel under the external force were obtained.Then,the structure parameters of rasp bar were studied through EDEM simulation experiment,and the working parameters were determined through test-bed experiment.Finally,the simulation experiment results and test-bed experiment results were verified through field experiment.The results showed that when the threshing cylinder speed was 356 r/min,the concave clearance was 40 mm,the installation distance of rasp bar was 250 mm with 50Mn steel,and the feeding amount was 8 kg/s,the kernel broken rate was 1.93%,which satisfied the requirements of maize harvest standard.This study proved that the DEM(Discrete Element Method)can be adopted to guide the optimization design of mechanical structure,and it has certain value for the research and development of operation equipment of other agricultural crops.

Unbalanced variation after assembly and double-speed influence coefficient method in the threshing drum

Though the component of threshing drum is pre-balancing on the factory,the drum after assembly still has the problem of unbalanced vibration.In this study,the unbalance mechanism produced by assembly are introduced and the centroid propagation model in the series rotation system was established.The influence of the eccentricity and assembly phase on the assembly unbalance was studied.It is shown that there was a superposition effect between the initial centroid eccentricity caused by the machining error and the centroid eccentricity caused by assembly error,the unbalance amount under the in-phase assembly was larger than that of the anti-phase assembly.Moreover,the unbalance variation was experimentally investigated using in-field balancing detection on the test rig and combine harvester.The experiment results showed the excellent vibration reduction effect of in-field balancing,which showed a reduction of 83.0%and 85.8%.In order to increase the range of in-field balance detection and reduce the calculation error,the double-speed influence coefficient method was proposed.The proposed method adopted the way of first low-speed pre-balancing,and then high-speed precision balance,taking advantage of vibration information at two speeds and avoids nonlinear vibration conditions caused by high unbalanced vibration.Finally,the double-speed influence coefficient method was verified on the test rig.The vibration reduction effect of proposed method was better than the traditional method.

Review of grain threshing theory and technology

Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impact,rubbing,combing and grinding.Four types of contact models between grain and threshing components have been constructed correspondently.Grain damage can be regarded as a function of peripheral velocity and contact pattern of impacting.Grain loss can be regarded as a function of contact pattern of rasp bars.Grain loss coming from cleaning and separation in the subsequent process of combing threshing was significantly decreased.Tangential and axial threshing technologies have been applied in grain threshing system widely.It showed that in the combined application,tangential rolls are used to accelerate grain flow,and axial rolls are used to increase threshing quality especially lower loss and damage.Conical concave may take the place of the traditional cylindrical one.With the development of sensor technology and communication technology,intelligent harvesting robot and automatic threshing system will be integrated together to improve grain quality and operation comfort.

Motion simulation and test on threshed grains in tapered threshing and transmission device for plot wheat breeding based on CFD-DEM

Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,and reduce the remaining seeds in the device,the numerical simulation was carried out on the motion process of materials in the longitudinal-axial tapered cylinder threshing and transmission device of the plot wheat breeding combine harvester based on CFD-DEM method.Simulation results showed that,threshing and transmission of particles and short stalks at axial direction could be realized under the influence of air flow.Meanwhile,the material transference and distribution rule and stream field distribution rule of air flow in the threshing and transmission device were obtained,the variations of velocity and displacement of particles and short stalks with time were obtained;the motion trajectories and forms of particles in different types of retention were also studied.At rotating speed of 1300-1600 r/min for the tapered threshing cylinder in the verification test,the particle retention rate in the enclosure was 0-0.13%,while in the simulation the particle retention rate in the enclosure was 0-0.11%,only a 0.02%difference between them.The results proved a favorable feasibility to simulate the working performance of the tapered threshing and transmission device for plot breeding through gas-solid coupling method.

Design and performance analysis of tangential-axial flow threshing device for oat harvester

Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a belt conveyor,a tangential-flow threshing drum,an axial-flow threshing drum,a high-speed camera and a testing device.According to a regression orthogonal test method,using the rotation speed of the axial-flow drum,the horizontal center distance,and the vertical height difference of the two threshing drums as experimental factors;using the mass fraction of long stalks and the threshing rate as experimental indexes,a mathematical regression model of factors and indexes was established,and combined parameters were analyzed for the threshing quality and crushing ability.Experimental results showed that this device had the best crushing performance when the rotation speed of the axial-flow drum was 850 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm,and this device had optimal threshing performance when the rotation speed of the axial-flow drum was 760 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 20 mm.The parameters were optimized by Design-Expert 11 to obtain an optimization result that the rotation speed of the axial-flow drum was 800 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm.A verification experiment was carried out by using a high-speed camera,and the two groups of parameters were selected for a comparative experiment.Images of material movement between the two threshing drums were captured by the high-speed camera.Experimental results showed that the optimized parameters were beneficial to improving the threshing performance and anti-winding performance of the oat threshing process.This study provides a technical basis for the research and development of oat combine harvesters.

Method for measuring rice grain internal damage degree undergoing threshing force

During the threshing process of rice,the grains fall off the head of the rice ear due to the impact of the threshing bar.At the same time,the impact force of the threshing element causes a certain degree of damage to the grain.However,there are relatively few methods to analyze the internal damage of rice grains during the threshing process.In this study,the connection force between rice grains and stalks and the compressive bearing capacity of the grains were tested on a push-pull test machine,and then the critical impact force and velocity of rice grains during plastic deformation and brittle fracture were obtained by Hertz theory.On this basis,the quantitative evaluation model of grain internal damage was established through the extraction and calculation of the damaged area inside the grain,and the damage degrees inside the grain under different loading times and loading forces were analyzed.The results showed that the average threshing force required for rice grains is 1.57 N(variance is 0.0529),and the critical impact forces for plastic deformation and brittle fracture of the grains during threshing are 138.79 N and 145.77 N.Since the threshing force during the threshing process was 43.9-71.9 N,it could be known from the internal damage model that the grain is in the safe loading area.Under the same load,the vertical pressure causes the most damage,the lateral pressure takes second place,and the positive pressure was the least.The results of this study can provide a basis for the development of combine harvester and rice grains damage evaluation.

Simulation and test on separating cleaning process of flax threshing material based on gas-solid coupling theory

In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.

Migration law of flax threshing materials in double channel air-and-screen separating cleaner

In order to further clarify and improve the working performance of separating cleaner for flax threshing materials,and study the migration law and characteristics of components of flax threshing materials during separating and cleaning,in this paper,a gas-solid coupling simulation model was established on the separation cleaner for flax threshing materials and a numerical simulation was carried out on the separating and cleaning process.Simulation results showed that,the separating and cleaning effect of the components of flax threshing materials was good under the air-and-screen gas-solid coupling flow field.Meanwhile,the form distribution and the vector distribution of air volume and velocity of flax threshing materials in the air-and-screen devices were obtained.By referring to the migration trajectories of the flax threshing materials in the vibration sieve device,double channel residue collection device and dust absorber,the volume variation,motion trajectories and variation of migration velocity of the components of flax threshing materials over time in different regions were explored.Verification test results showed that,the content impurity rate of the separation cleaner for flax threshing materials was 2.06%,and loss rate in cleaning was 3.08%.Compared with simulation results,the verification test results were 1.23%and 0.42%higher,showing that the established discrete element model on the flax threshing materials and parameter setting were basically feasible.The verification test also verified the correctness of the simulation results of the separating and cleaning process of the flax threshing materials based on gas-solid coupling theory and the feasibility of the research method.

Measurement and simulation of the suspension velocity of flax threshing material using CFD-DEM

In order to explore the aerodynamics characteristics of flax threshing material,and accurately obtain the movement trajectory of the material of each component in air-screen cleaning,the suspension velocities of flax grains,capsules,short stalks and capsule husks at different stages were measured by means of the suspension velocity device.The experimental results showed that the suspension velocity range was 4.55-8.64 m/s for flax grains,6.46-10.90 m/s for flax capsules,3.23-7.75 m/s for flax short stalks,and 1.06-4.21 m/s for flax capsule shells.Based on the experimental results,the overall interval distribution of each component of flax threshing material and the separation characteristics were discussed and the discrete element model of each component of the flax threshing material was established.Through simulation measurement of angle of repose of the material and the sliding friction angle with steel,the reliability of the established model was verified.The gas-solid coupling method was used to simulate the suspension velocity of each component of the flax threshing material,and the suspension velocity of the four components of flax threshing material was obtained.The simulation measurement results were within the actual measurement range,showing that the test results were basically in line with the simulation results.The simulation on the suspension velocity of different components of flax threshing material based on gas-solid coupling had high precision degree.Therefore,the feasibility of the suspension velocity of the flax threshing material measured in the simulation test based on CFD-DEM coupling was verified.

Determination of threshing and separation unit performance of rosemary(Rosmarinus officinalis)plants

Rosemary(Rosmarinus officinalis L.)is an important perennial medicinal and aromatic plant belonging to the Lamiaceae family.Rosemary is widely produced in Turkey for its oil which can be extracted from the plants when flowers are in buds.In Turkey,a significant amount of domestic and foreign trade of rosemary is conducted.In 2018-2020,2088 t of rosemary plants were imported,while in the same years 2077 t were exported.In this study,the performance indexes of a threshing and separating unit designed according to the physicomechanical properties of the rosemary were determined.The operating parameters of the machine were determined at three different moisture contents and adjusted according to the harvest moisture values.The threshing efficiency,work efficiency,power requirement,and specific energy consumption values of the threshing unit were determined,while separating efficiency,work efficiency and specific power consumption of separating unit of the developed system were determined.According to the study results,the threshing efficiency of the rosemary plant varied between 44.00%and 96.97%.Work efficiency of the thresher varied between 1.18 and 15.34 kg/h.Power requirements and specific energy consumption of the threshing unit were obtained as 0.19-1.05 kW and 0.02-0.37 kW·h/h,respectively.On the other hand,the separating efficiency of the separating unit for the rosemary plant varied between 44.27%and 85.24%.Maximum and minimum values of work efficiency were found as 0.75 kg/h and 5.52 kg/h.Specific power consumption of the unit ranged from 3.95 to 39.95 kW/kg.

Movement law of the threshing material in threshing and cleaning machine for plot-bred wheat

In order to clarify and enhance the work performance of the threshing and cleaning machine for plot-bred wheat and further reduce the grain retention in all working areas in the machine,in this study,a discrete element model for the threshing material of plot-bred wheat and a gas-solid coupling simulation model for the machine were established by ensuring all the harvesting criteria for the machine.Then numerical simulation was completed on the movement process of the threshing material in the threshing and cleaning machine for plot-bred wheat,the movement law and motion trajectory of all components of the threshing material were explored,and the impact forms of unreasonable work parameters on the separating and cleaning process were analyzed.First,four working areas were divided in the threshing and cleaning machine for plot-bred wheat.Under gas-solid flow coupling effect,the number variation of threshing material in each working area was analyzed under the effect of gas-solid coupling,and the operation characteristics of“no retained seeds and convenient cleaning”of the threshing machine for plot-bred wheat were further improved.The verification test results showed that,when the feeding amount of wheat was 0.30 kg/s,the rotation speed of the shaft of the tooth-type threshing cylinder was set to 1350 r/min,the rotation speed of the winnower was set to 500 r/min,the rotation speed of the residue absorption fan was set to 1000 r/min,the average total loss rate in threshing of the sample machine was 0.56%,and average impurity rate of the threshing material was 5.26%,average damage rate in threshing was 0.68%.In the test,the status of material discharged from the residue absorption fan outlet and bottom of the cyclone separator was similar to that of the simulation results,showing that it was feasible to use the method of gas-solid coupling to simulate the movement law of threshing material in the threshing and cleaning machine for plot-bred wheat.

Comparing kernel damage of different threshing components using high-speed cameras

Grain damage research has been a focus of many experts in the agriculture machinery industry.A threshing test-bed was developed to investigate the movement and influence of different threshing and separating units on maize grains.The damage to maize grains was analyzed with a high-speed camera to observe the movement and damage received by the maize grains.The results showed that the threshing and separating effects of the perforated concave plate were obviously lower than that of the round steel concave plate,the threshing effects of the rigid rasp bar and polyurethane rasp bar were similar,and the damage ratio of the polyurethane rasp bar was relatively low.It also indicated that moisture content has a significant effect on the damage ratio and damage type of maize grains.The different threshing component types used in this study had an obvious effect on the degree of damage to high moisture content maize grains and the damage to high-moisture kernels during threshing could be further identified.The results can provide a reference for the design of threshing and separating devices in the maize combine harvesting machinery.

The status and prospects of in situ grain harvesting technology and its machine system

Two main types of in situ grain harvesttng machine are introduced. The comparison of their working principles and advantages are given. The limitations and prospects for stripper header are discussed.