| Rice mechanized hole direct seeding technology is an advanced and simplified planting method which saves time and labor,saves cost and improves efficiency.However,the adaptability of existing rice hill-drop direct seeding machines to different grain types and the precise adjustment ability of sowing amount still need to be improved.Therefore,on the basis of previous studies,this paper optimized and designed a seed metering device with stepless adjustment of sowing rate,and developed a high-speed passenger rice precision hole direct seeding machine with the power chassis of high-speed passenger transplanter as a supporting power,aiming to promote the popularization and application of rice mechanized hole direct seeding technology in suitable areas.The main research contents and conclusions are as follows :1)Optimal design of sowing amountstepless adjusting hole-type metering deviceIn order to further improve the adaptability of the seed metering device with stepless adjustable seeding rate to different grain types of rice seeds and its precise adjustment ability of seeding rate,the influence of filling posture in the hole on the sowing effect during the filling process of the seed metering device was analyzed and studied.The kinematics model of rice seed returning filling in the second filling chamber of the seed metering device was constructed.Combined with the high-speed photography experiment,Huanghuazhan was used as the experiment variety.Under the conditions of 12mm-14 mm diameter of the type-hole,30r/min-50r/min rotation speed of the seed metering wheel and3mm-7mm depth of the type-hole,the primary and secondary factors affecting the number of returning filling seeds were determined.The effect of type-hole diameter was significant,but the effect of wheel speed and type-hole depth was not significant.The primary and secondary factors affecting the filling posture(vertical and oblique),such as the hole depth,the rotation speed of the seeding wheel and the type-hole diameter,were verified.The type-hole depth had significant influence on the filling posture,while the rotation speed of the seeding wheel and the type-hole diameter had no significant influence on the filling posture.Furthermore,the key structures of seed metering device,such as the diameter of seed metering wheel,the section of hole,the number of hole,the depth of type-hole,the diameter of type-hole,and the depth of type-hole,were optimized,and the diameter of seed metering wheel was 55 mm,the section of hole was round,the number of type-hole was 8,the depth of hole was 3 mm-8 mm,the diameter of hole was 12 mm-15 mm,and the angle between the contact inclined plane of the top rod slider and the horizontal plane was 30°.2)Performance experiment of seed metering deviceThe short grain type Yongyou 12,medium grain type Huanghuazhan and long grain type Wanxiangyouhuazhan were used as experiment varieties,and the type-hole diameter(12mm-15mm),rotation speed of metering wheel(30r/min-70r/min)and type-hole depth(3mm-8mm)were used as experiment factors.The average number of type-holes,coefficient of variation,qualified rate of number of holes and hole rate were used as evaluation indexes to carry out the performance experiment of all-factor metering device.The effects of hole diameter,rotation speed of metering wheel and type-hole depth on the sowing performance of different grain type rice varieties were clarified.The coefficient of variance in average seeds number per hole less than 40% of,hole rate is less than 5% and the qualified rate of seed number is more than 85%,the optimal hole diameter is 13 mm and the hole depth adjustment range is 3mm-8mm.The average seed number of Yongyou12,Huanghuazhan and Wanxiangyouhuazhan is 5-9,4-7 and 3-6.The prediction models of seed sowing amount of different grain types were established,and the correlation coefficient was 0.934.3)Whole Machine Design and Field ExperimentBased on the seed metering device developed above,the structure,working principle and main technical parameters of the high-speed passenger rice precision type-hole direct seeding machine were determined by taking the power chassis of the high-speed passenger transplanter as the supporting power and according to the agronomic requirements of rice mechanized type-hole direct seeding technology.Other key components such as limit support horizontal profiling mechanism,elevation profiling mechanism,ditching and ridging slide plate,main beam and transmission system were designed and experimented for prototype processing.Then,referring to DG/T 083-2021 rice direct-seeding machine promotion appraisal outline standard,taking Yexiangyouhang 1573,Huanghuazhan and Wanxiangyouhuazhan as experiment varieties,the field performance experiment and production experiment of the whole machine were carried out.The experiment results showed that the qualified rate of the number of seeds per row of the whole machine was higher than 85%,and the error between the actual number of seeds per row and the seeding rate prediction model was 2.33%-5.80%.In addition,the results of actual cutting and yield measurement in Poyang County,Xinjian District and Yuanzhou District showed that the rice yield of mechanical direct seeding treatment was higher than that of artificial direct seeding treatment,and the yield per mu was increased by 29.3 kg-79.7 kg,with an increase of 7.09 %-17.72 %. |
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