Experimental Study On Axial-flow Peanut Picking Device With Bending-tooth Screw Roller

In China peanut is a very important oil crops, the planting area is 4.75×106hm2, the total production is 1.7×106t in 2016, ranking first in the world. Though peanut production is larger than other country, but the peanut havest mechanization technology and application is lower than the United State, China peanut harvest mechanization level is just 29.44%, mainly depend on artificial and small machine for segmentation harvesting, but low efficiency and high labor cost restrict healthy and stable development of peanut industry. The picking is one of very important link in peanut harvest mechanization, the quality of the picking device determine the harvest efficiency and the peanut quality in post harvest. Combination with the National Science Foundation general program :"Reasearch on the full-feeding peanut picking dynamic damage mechanism and low damage picking device" (5157367) and fund for the Doctoral Program of Higher Education Project "peanut picking combine core institutions working mechanism and key technology" (project number: 20122103110009)carrying out, for solve the axial-flow picking device problem that bad transporting, twining, low picking efficience, high pod broking rate and poor cleaning apply in peanut combine, picking combine and picker-only. Further study the axila-flow full-feeding device's sturcture,mechanic and different peanut variety physics mechanical properties influence picking, and establish the peanut plant and picking roller modeling and simulating, developing the axial-flow full-feeding bending-tooth screw picking device and cleaning device with double air-suction inlets with vibration screen, and testing the parameter and performance. The research result can provide essential reference for desinging peanut picking combine and two-stage peanut combine's picking device.The main contents and conclusions are as follow:(1) Introducing the United States and China peanut harvest mechanization characteristis and the mian harvest machinery type, comparing the United States screep and China erect type peanut picking characteristics, and confirem the technology road.(2) Confirm axial-flow full-feeding peanut picking device scheme. Compare with the semi- and full-feeding peanut picking device's structure, working principle and picking characteristics, get a conclusion that the tow-stage harvest pattern suitable to our country. The peanut picking combine is major equipment to fulfill peanut picking in two-stage harvest pattern, for descrease the machine volume, increase picking time and picking rate, in this paper the picking device scheme choose the axial-flow full-feeding peanut picking device.(3) Testing research different variety peanut plant physical mechanical character.Measuring three varietys peanut height, pod number, friute range and depth, obtained these parameter distribution range; analysis the relationship between peanut stem, plant and stem,pod and stem tensile strength with moisture, the relationship between peanut straw shearing strength with moisture; measuring friction coefficient between peanut plant with different material surface. To supply theoretical basis for design peanut picking device.(4) The picking roller force analysis, dynamics simulation and parameter test.Analysising the peanut plant stress in picking roller and establsh mechanical model; designing the picking roller length, revolving speed, diameter, intersection angle between screw and roller generatrix, bending-tooth structure and arrangement, concave form and sieve pore dimension; the paper mainly researc the floating coefficient of the pick out materials, and the extraction material distribution principle in picing roller axial and radical direction, design air-suction inlets with vibration screen pod cleaning device, and ascertain the parameter.(5) In the whole picking the impact force is little; through orthogonal test and optimizing confirm the picking roller key parameter, including intersection angle between bending tooth and roller generatrix, bending angle, intersection angle between screw and roller generatrix.(6) Establishing picing roller and plant soild model, analysising picking roller 6 steps model, obtained that the roller vibrational frequency and machine vibrational frequency are not in the same interval avoid resonance; peanut plant flexible handling with ANSYS softwear, and putting the flexible peanut plant and picking roller body guide to ADAMS to simulate, abtaining the peanut plant displacement, speed, acceleration and stress curve in picking device, the result is that the peanut plant moving as helical line,(7) Performance testing for axial-flow full-feeding picking.Test result show that different peanut variety picking rate more than 98%, the picking device account for more adaptation,the other three factors have a great influence to picking, the influence rule is that the picking rate increase and broking rate decrease following with the picking gap decrease, the feed quantity increase and decrease will cause picking rate decrease, and meanwhile broking rate increase, the picking rate increase following with picing roller rotating speed increase, and meanwhile broking rate increase. The peanut variety "Huayu30" is selected as test materials,the three parameters: picking gap, feed quantity, rotating speed of cylinder are selected as experimental factors, the peanut picking and breaking rate are selected as experimental indexes. Through orthogonal test, the mathematical model is builded with the experimental factors and indexes and studied on the response surface optimization. The working parameters of picking performance are optimized, obtain the optimal parameter of the picking cap,feeding quantify and rotating speeding, after verification test, the conclusion is obtained that the peanut picking rate and the peanut breaking rate is good.