Amending Research on the Expression of the Contact Force of the Spindle Barrel Finishing Based on EDEM Simulation

The spindle barrel finishing is commonly used to improve the surface integrity of the important parts of the high-end equipment while it is difficult to provide enough test artifacts for the traditional trial and error experiment to obtain the desirable processing technology.The EDEM simulation of the spindle barrel finishing can provide effective help for the process design,however,the difference between the simulation and experiment is closely related to the selection of the contact model during simulation.In this paper,simulations and experiments are conducted based on the identical apparatus and conditions to facilitate the comparison and validation between each other.Based on the Hertz contact theory,the effect of the material properties of contact objects and the relative position of the workpiece on the contact force is qualified.The expression of the correlation coefficient of the contact model is deduced.Then the formula for calculating the contact force between the barrel finishing abrasive and the workpiece that includes influence coefficient of the material properties and the relative positions is established.Finally,the contact force calculation formula is verified by changing the rotating speed.The result shows that the material correction coefficient ranges from 1.41 to 2.38,which is inversely related to the equivalent modulus E.The position correction coefficient ranges from 2.0 to 2.3.The relative error value between the calculation result and the experimental test result is from 0.58%to 14.07%.This research lay a theoretical foundation for the correction theory of the core elements of the spindle barrel finishing process.

Seeding Performance Simulations and Experiments for a Spoon- Wheel Type Precision Cottonseed-Metering Device Based on EDEM

To study the effects of seed metering on seeding performance under different motion parameters,a simulation model for a spoonwheel type seeder was established.A seed meter was tested by using EDEM(Engineering Discrete Element Method)software to simulate its working process at different speeds and tilt angles.The trajectories of individual cottonseeds in the seed-metering device were obtained,concurrently,the stress trend in the grain group was determined as a function of time.The simulation results suggest that at larger speeds,the metering index of the seed meter gradually decreases,while the index and the missing index gradually increase.As the tilt angle increased,the multiples index and missing index gradually decreased,while the multiples index gradually increased.When the seed meter speed reached 50 r/min and the tilt angle was 15°,the seed meter had a relatively good working performance with a seed spacing acceptance index of 92.59%,a multiples index of 1.85%,and a missing rate index of 5.56%.The seed meter was tested on a bench by using a JPS-12 performance-tester bench.At the aforementioned speed and angle,the coefficient of variation for the cottonseed spacing was 2.1%.The field trial results indicated that the multiples and the missing rates were higher than those for the tester bench but still met a passing rate of more than 90%.The coefficient of variation for the seed spacing was less than 10%,suggesting that the design could be used for field sowing.The resulting seeding uniformity was higher under these conditions,which indicates that the seed meter has a better working performance and the bench has a good seeding effect.

Research and optimization of the hand-over lifting mechanism of a sweet potato combine harvester based on EDEM

In order to meet the challenge of high loss rate and high tuber injury rate during the operation of the 4UZL-1 sweet potato combine harvester,the sweet potato tuber hand-over lifting mechanism was designed based on a comprehensive analysis of the entire structure of the harvester.Taking the average normal force on conveying sweet potato tubers as evaluation indexes,the EDEM simulation experiment was carried out considering the factors of the angle of the excavating and conveying mechanism,the conveying angle of the scraper chain,the speed of the excavating and conveying mechanism,and the speed of the scraper chain conveying.The experimental findings indicated that the optimal operational performance of the hand-over lifting mechanism was achieved at a speed of 1.15 m/s for the excavating and conveying mechanism,an angle of 24°for the excavating and conveying mechanism,a conveying speed of 0.66 m/s for the scraper chain,and a conveying angle of 60°for the scraper chain.Field experiments were conducted based on the EDEM simulation experiment,using the loss rate and the injury rate of conveying sweet potato tubers as evaluation indexes.The results showed that the hand-over lifting mechanism demonstrated optimal operational effectiveness with an excavating and conveying mechanism angle of 20°,a scraper chain angle of 68°,an excavating and conveying mechanism speed of 1.2 m/s,and a scraper chain speed of 0.66 m/s,while the machine running speed was maintained at 1 m/s.At the moment,the hand-over lifting structure exhibited a loss rate of 1.12%and a tuber injury rate of 0.94%.The conclusions obtained serve as a valuable reference for future research and optimization of sweet potato combines.

Study on multi-size seed-metering device for vertical plate soybean precision planter

Aiming to solve the problem of small range of the appropriately sowing seeds existing in a vertical disc seed-metering device,the planter plate series with four sizes were developed according to the variety and size distribution of all soybeans in China.The structure and working principle of the vertical disc soybean seed-metering device were detailed,and the influence of the diameter of soybean on the working performance of the seed-metering device was analyzed through the software EDEM virtual simulation,so as to achieve the goal of covering the soybean seeds with all sizes by the minimum planter plate series as well as to obtain the most appropriate operating speed of each planter plate by optimization.For the planter plates with the hole diameter of 7,9,12,16 mm,the appropriate size ranges of sowing seeds are 4.5-6.0,6.0-8.0,8.0-10.5,10.5-13.0 mm,respectively,and the appropriate operating speeds are 9,8,7,6 km/h,respectively.The results show that this planter plate series can meet the requirements of seeding with all sizes of soybeans at the range of the most appropriate operating speed.The study method can provide a reference for design and optimization of precision planters.

Model construction of soybean average diameter and hole parameters of seed-metering wheel based on DEM

To satisfy the demands of soybean precision sowing,this article starts with statistics of the physical parameters of soybean seeds in Heilongjiang province,China.The filling process of soybean seeds was analyzed,and the ratio relationship between the diameter,depth,chamfer length of seed-metering wheel’s holes and the mean diameter of soybean seeds was determined.EDEM was used to simulate seeding circumstances of hole seed-metering wheel with different holes’sizes.The hole diameter ratio,hole depth ratio,and chamfer length ratio were the test factors,while the percentage of single multiple and the empty seeds were test indexes.The triple quadratic regression orthogonal rotation combination test was designed,and the mathematical model between test indexes and test factors was established.Results showed that the influence of hole diameter ratio and hole depth ratio was significant(p<0.01)in the case of single,multiple and empty seed percentage while chamfer length ratio was only significant in single seed percentage compared to multiple and empty seeds percentage(p>0.05).The chamfer length ratio was 0.15,the hole diameter ratio was 1.63-1.73,the hole depth ratio was 0.81-1.20,the quality of seeding index was more than 90,and multiple and missing indexes were less than 6%and 4%,respectively.The soybean hole wheel seeding device was produced under the optimal parameter combination,to perform a comparative verification test with non-optimized parameters.The test showed anastomotic simulation results,verified the validity of the simulation.The seeding device after optimization expressed the best operating performance,which might satisfy the demands of soybean precision sowing.The study results can provide a theoretical reference for the optimization design of soybean seeding devices.