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,...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.展开更多
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 see...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.展开更多
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 r...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.展开更多
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 perce...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.展开更多
[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 threshi...[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.展开更多
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 proc...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.展开更多
In this paper, we study the threshold result for the initial boundary value problem of non-homogeneous semilinear parabolic equations {μt-△μ=g（μ）＋λf（x）,（x,t）∈Ω×（0,T）,μ=0,（x,t）∈ Ω×[0,T）...In this paper, we study the threshold result for the initial boundary value problem of non-homogeneous semilinear parabolic equations {μt-△μ=g（μ）＋λf（x）,（x,t）∈Ω×（0,T）,μ=0,（x,t）∈ Ω×[0,T）,μ（x,0）=μ0（x）≥0,x∈Ω.By combining a priori estimate of global solution with property of stationary solution set of problem （P）, we prove that the minimal stationary solution Uλ（x） of problem （P） is stable, whereas, any other stationary solution is an initial datum threshold for the existence and nonexistence of global solution to problem （P）.展开更多
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...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.展开更多
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 designe...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.展开更多
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 an...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.展开更多
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 impac...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.展开更多
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,an...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.展开更多
文摘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.
基金supported by the earmarked fund for China Agriculture Research System(CARS-02-10)the Special Fund for Agro-scientific Research in the Public Interest,China(201303002)the National Natural Science Foundation of China(31771891)
文摘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.
文摘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.
文摘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.
基金Supported by Science and Technology Project of China Tobacco Guizhou Provincial Corporation(201918)Guizhou Province Academic Pioneer and Academic Pioneer Construction。
文摘[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.
基金Science and Technology Foundation of Hunan Branch of China National Tobacco Corporation(HN2020KJ14,HN2020KJ17).
文摘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.
基金supported by Natural Science Foundation of China(10971061)Hunan Provincial Innovation Foundation For Postgraduate(CX2010B209)
文摘In this paper, we study the threshold result for the initial boundary value problem of non-homogeneous semilinear parabolic equations {μt-△μ=g（μ）＋λf（x）,（x,t）∈Ω×（0,T）,μ=0,（x,t）∈ Ω×[0,T）,μ（x,0）=μ0（x）≥0,x∈Ω.By combining a priori estimate of global solution with property of stationary solution set of problem （P）, we prove that the minimal stationary solution Uλ（x） of problem （P） is stable, whereas, any other stationary solution is an initial datum threshold for the existence and nonexistence of global solution to problem （P）.
基金financially supported by Key Science and Technology Project of Gansu Province(Grant No.21ZD10NF003-4-01)Department of Agriculture and Rural Areas of Gansu Province Agricultural Machinery Equipment Remediation Project(Grant No.niyf2022-02)+1 种基金Fuxi Young Talents Fund of Gansu Agricultural University(Grant No.Gaufx-03Y01)Youth Tutor Fund of Gansu Agricultural University(Grant No.GAU-QDFC-2021-08).
文摘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.
基金This work was financially supported in part by the National Natural Science Foundation of China(Grant No.52175258)the Major Scientific and Technological Innovation Projects of Shandong Province(Grant No.2018CXGC0217).
文摘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.
基金National Natural Science Foundation of China (Grant No.51975257)National Key Research and Development Project (Grant No.2017YFD0700200).
文摘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.
基金This work was supported by the National Natural Science Foundation of China(51705193)National Key Research and Development Project(2017YFD0700302)the Science and Technology Development Project of Jilin Province(20170204016NY).
文摘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.
基金The authors acknowledge that this work was financially supported by China Agriculture Research System(CARS-14-1-28)Discipline construction fund project of Gansu Agricultural University(GAU-XKJS-2018-189)National Natural Science Foundation of China(Grant No.51365003).
文摘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.
