Research And Optimization Design Of Cutting Mechanism In Garlic Combine Harvesting

Garlic planting cultivation has a long history in China, both the garlic planting area and total output rank first in the world. But the development of production mechanization still lags behind, especially the harvest operations, mainly depends on artificial work and semi-mechanization, in the process of harvest, the garlic roots were carried with wet dirt when just been pulled out from the soil, which caused mildew at the bottom of the garlic in the process of post-harvest drying, affecting the storage and sale of fresh garlic, a waste of storage space in the process of transportation, increasing the transportation cost as well. Currently, cutting garlic roots is mainly relied on artificial work, therefore, developing garlic combine harvester cutting roots equipment technology has important actual significance. The main research contents are briefly summarized as follows:⑴ Aiming at cutting roots mechanism adapt to different sizes of garlic as a goal, a research idea about realizing garlic body copying, configuration of rotary type cutting roots knife as the main cutting roots operation totality was put forward. And the main experimental body composed of the main clamping chain conveyer, sorting- alignment device, body frame and so on was designed, the whole transmission system was configured as well.⑵ Typical garlic varieties in major producing areas were applied as the research objects, analysis in garlic shape characteristics was started, garlic copying wheel with contour curve was designed based on statistical data, copying wheel had relative motion in contact with the garlic in the process of cutting roots, guiding garlic roots beam into the cutting roots passage, in order to compare the effects of copying, two kinds of copying wheels were made, 42、106 mm diameter respectively, equipped with high speed rotary cutter in the cutting roots passage, the roots were separated from garlic with the help of shear force.⑶ Copying wheel and independently powered rotary type roots cutting knife were installed on the floating frame, constituting the floating cutting roots mechanism. The floating frame can be dismantled, which was convenient for replacement of copying wheel, cutting knife and other parts in the subsequent tests. The overall structure design of floating cutting roots mechanism was founded based on garlic stress analysis and stress analysis of mechanism, the choice of appropriate value of suspension spring tension, which taking garlic head could not be crushed as the standard, theoretical analysis was conducted in the process of contact between garlic and copying wheel, explanation equation about effective roots cutting times was obtained, in which effective length of cutting roots lg was used as the core variable, the optimal value of effective length of cutting roots was determined by tests, figuring out the suited minimum linear speed of cutting roots knife was 10.5m/s.⑷ Aiming at parts of garlic roots couldn′t be accurately into the cutting roots passage in early experiment because of structural problems, the garlic body guide board part was designed, and flat parabolic trajectory model was used to analyze the guidance of the optimal effect, structural parameters of garlic body guide board part were determined. The whole experimental facility, which in turn realized the garlic stem upper surface height-aligned, transverse location guidance and garlic body space posture adjustment, making sure garlic roots could enter the passage, separating from the garlic head.⑸ 3d design software UG was utilized for virtual prototype design such as the main body of experimental facility, the floating cutting roots mechanism, etc. Error source and optimization design of the whole configuration was checked systematically, physical prototype was produced on this basis after that.⑹ Aimed at average residual roots length, cutting rate of garlic roots, garlic loss rate caused by cutting, operation parameters of cutting roots experimental facility were optimized, four factors which affecting roots-cutting quality were determined by single factor experiment such as rotation rate of cutting roots knife nf, main clamping chain conveyor speed vz, copying working parts and bottom clearance hd*, cutting rate of garlic roots and garlic loss rate caused by cutting were utilized as the evaluation indexes, orthogonal tests for the above four factors were conducted, weighted mark method was used to make a comprehensive analysis, primary and secondary relations and significance of the influenced factors were determined, the optimal operation parameters combination of the cutting roots experimental facility were obtained: linear velocity of cutting roots knife was 12.3m/s, the chain conveyor speed was 0.8m/s, the diameter of guarded fence was 2mm, bottom clearance was 15 mm, optimized cutting rate of garlic roots was 88.3%, garlic loss rate caused by cutting was 2.3%, the theoretical cutting roots efficiency of combine harvest was 6 per second.