Design And Experimental On Stripping Cutting Table Of Rape Combine Harvester

Rapeseed is the second to the soybean as oil crops all over the world. Chinese plant area was more than 7.95 million hectare in 2014 and it accounted for 54.03% of the total area of oil crops. The yield of rapeseed was 14.77 million tons and it accounted for 42.12% of total production of oil crops in China. Rape mechanization harvest level in 2014 is only 25.32% and the problem of low efficiency and high cost of artificial harvesting rape had become a bottleneck which restricts the production of rapeseed in China. Therefore, it is of practical value for the production of rape to develop a efficient rape combine harvester. This topic developed a stripper cutting table for rape combine harvester which aimed at rape plant biological characteristics and mature pods of breakage characteristics and in order to reduce the feed quantity, improve the adaptability, reduce the power consumption of the rape combine harvester. It provided a new method of the structure design of rape combine harvester. The major points were generalized as follows:(1) Structure design of stripping cutting table was defined. On the basis of systematic analysis of the current situation of the research on the domestic and foreign traditional combine harvester and stripping combine harvester, it was put forward that the stripping drum and the reel slat were combined to strip and the cutting device and cover casing were as an auxiliary. The working process and principle of stripping cutting table were defined.(2) Studied on mechanical and physical properties of pod. In view of the pods and stem joints, tensile tests were performed to obtain the position of stress and strain curve. The test showed that the tensile process can be divided into four stages: pre-stretch, linear elastic, yielding and fracture. There was obvious yield stress at the joints of pods and stem, and the maximum value was 16.0 N, the average value was 11.7 N.(3) The design principle was put forward that the surface projection of the moving track of the stripping element should cover all the crops. The variation of restripping rate and leakage rate were obtained, which was decided by the size and inclined angle of single stripping element, the arrangement mode and spacing of stripping elements.(4) Finished the design of key parts, the structure parameters and motion parameters of the reel slat, the stripping drum, the cutting device and the cover casing were determined. And the reasonable parameter combination was defined. The constraint equations of the position and the kinematic parameters of the main working parts were proposed according to different growth conditions. The stripping elements were fingers style, the distance of fingers was 70 mm, the axial quantity of fingers was 12, the angle of finger was 160°, the axial obliquity was 80°, the effective extended size was 280 mm, the radius of stripping drum was 355 mm, the rotation rate was 240~340 r/min. The installation position and motion parameters of reel slat were adjusted according to the requirement of stripping.(5) The integrated design of complete machine was put forward and the structure, space layout, working process, technical parameters has been determined. The cutting width of combine harvester which was equipped with stripping header was 0.9 m, its feed quantity was 0.21~0.95 kg/s, its operating speed was 0.4~1.8 m/s, its operating efficiency was 0.13~0.58 hm2/h and the power of its engine was 7.5 kW. The combine harvester was equipped with crawler walking device and its specific ground pressure was 9.2 kPa.(6) The simulation and analysis was carried out for the stripping drum, reel slat and the airflow field of the header. The simulation results showed that the matching of the moving parameters of the stripping drum and reel slat was reasonable and dialing down, stripping, pulling out and other processes could be realized in theory. The structure design, parameter selection, material selection of the stripping drum was reasonable and it could meet the needs of the stripping harvest. The result of airflow simulation showed that the cambered cover had better airflow field characteristics than the square enclosure. It was mainly reflected in:the internal pressure of the cambered cover was slightly less than the standard atmospheric pressure. It was advantageous to grab the crops and hold up the material, which had a positive effect on reducing the return loss and the loss of the splash. The inner flow field of the cambered cover was more smooth, stable and less in the vortex area.(7) The field experiments about the rape combine harvester which equipped with stripping cutting table were carried out. The field experiments showed that the stripping cutting table can achieve the intended function including pressing down, stripping, throwing, cutting and others. The whole machine works well and the material flow was smooth.