Design And Research Of Running Performance On Maize Stubble Harvesting-soil Preparation Combined Machine Based On VPT

With the rapid development of the world economy and society, the consumption of non-renewable energy is increasing, ecosystem is also becoming more and more serious, the sustainable development of human society is facing unprecedented challenges, the sustainable development and application of biomass energy is attracting the high attention of the world. As a kind of biomass resource for sustainable utilization, harvesting of corn stubble will produce some economic benefit and environmental benefit, at the same time, the removing of corn stubble can create good working conditions for the subsequent soil preparation and planting. In recent years, due to the impact of traditional modes of farming, agricultural production is also facing increasingly serious problem,such as soil degradation, loss of arable land, serious soil erosion, decrease of soil fertility and increasing of operating costs. In order to improve the grim situation, a lot of countries take the study of combined operation machine which is efficient, energy-efficient, water-saving as the main direction to solve this problem. Regarding the characteristics of agricultural mechanization of Jilin Province, the drawbacks of the current farming model and the development trend and basic research of combined operation, maize stubble harvesting-soil preparation combined machine is designed by virtual prototype technology(VPT).Basing on the 4GS-2 type maize stubble harvesting machine, a maize stubble harvesting-soil preparation combined machine is designed and the three-dimensional solid model of the machine is established. In view of the structural characteristics of the machine, the evaluation index of the running performance of the machine is determined to be the driving force, trafficability and the running stability. The analysis and calculation shows that the required towing force and powe of the whole machine is 17.2k N and 42.74 k W, the Dongfanghong-LX904 tractor can meet the requirement of the machine. The minimum ground clearance of the maize stubble harvesting-soil preparation machine is 365 mm, the approach angle is 14 °, the departure angle is 11 °, the lateral passing radius is 775 mm, the minimum turning radius is 4.9m, so the whole machine has a good trafficability. Then the running stability is analysised and calculated and the impact factor of the running stability is explored, the study provide a theorical basis for the whole machine’s improvement design and the stability design of semi-mounted agricultural unit.Depending on the stress characteristics of frame, the finite element static analysis of the frame is done in the condition of bending and torsion and bending combination, then the freedom modal analysis is also done by ANSYS. Results from the analysis show that the design of the frame can meet the application requirements.Lifting stability is an important evaluation index of the folding suspension device, study of lifting stability of suspension device is of great significance. Selecting the lifting stability of the first folding suspension device as an optimization goal, mathematical model of lifting Speed Ratio of the first folding suspension device and optimization objective function are established. The first folding suspension device is optimized by using Java language programming. The value of optimization variable(distance from the hinge point of lower link to the connection point of hydraulic rod and lower link) is identified as 450 mm. Basing on ADAMS, dynamics model of the first folding suspension device is established. Comparing the calculation results of mathematical model and dynamics model, they are proved to be right. Discussing the effect that parameters of the first folding suspension device have on its lifting stability, the result shows that: length of each link has little influence on the lifting stability of the first folding suspension device, the angle between the line which pass through the upper hinge point and the lower hinge point and horizontal plane has more influence on it.Rollover stability is one of the most important evaluation indexes to measure the running stability of unit, for the study deficiency of rollover stability of semi-mounted unit, this paper proposes a new method to characterize the rollover stability of unit. Choosing the Lateral Load Transfer Radio(LTR) as the evaluation indicator of rollover stability, the rollover mathematical model and rollover ADAMS dynamics model of tractor-maize stubble harvesting-soil preparation machine unit are established. Comparing the calculation results of mathematical model and dynamics model, they are proved to be right. Discussing the effect that parameters of the semi-mounted unit have on the rollover stability of the unit, the analysis result shows that: the maximum static rollover stability angle of tractor-maize stubble harvesting-soil preparation machine unit is 36.4 °, it can meet the request of national standards. The LTR of tractor is positively correlated to the height of its center of gravity and is negatively correlated to its wheel-base, so is the semi-mounted machine. In addition, the weight of tractor and the semi-mounted machine, the wheel-center-distance of the semi-mounted machine, the horizontal distance between semi-mounted machine’s center of gravity and the tow point and the height of the tow point of the semi-mounted machine also have influence on the LTR of tractor. The sensitivity analysis of each factor shows that: the height of center of gravity and the wheel-base of tractor are the important factors affecting its rollover stability, so are the height of center of gravity and the wheel-base of the semi-mounted machine. Except reducing the height of center of gravity or increasing the wheel-base, the rollover stability of semi-mounted machine can also be improved by reducing its wheel-center-distance and the height of the tow point or increasing its horizontal distance between the center of gravity and the tow point.