Steel roll round baler is one of the key technical equipment for straw harvesting in China. Currently, there is still a lack of basic design method for the core mechanism (steel roll round baler) of this machine. Based on the reverse engineering (RE) principles, plane geometry, material mechanics, mechanical design, test method and ANSYS analysis method, the reserve design method for the mechanism was carried out in this paper. Next, the relationship function among the four characteristic parameters, i.e, bale chamber radius, steel roll count, steel roll radius, and clearance between adjacent steel rolls, was established based on plane geometry; the contact model between the roll and the straw core was established by theoretical analysis, and the influence law of steel roll radius on contact force between them was determined by using highspeed camera observation method and probability principle. Moreover, the highspeed camera was also reutilized to determine the correlation of the occurrences of entanglement with the clearance between steel rolls and ridges on the steel roll surface. Combined with the test results and theoretical calculations, the dimensions of the feed inlet were designed. Afterward, the mechanical model of steel roll was established, and an important component of the steel roll, i.e, the longitudinal diameter, was designed. Furthermore, the stiffness and strength of the steel roll (assembly) were validated using the Workbench module in ANSYS. According to these findings, the reverse design with DN4575 round baler model as the design objective was carried out. The results of design were as follows: steel roller radius: 75 mm, number of steel rollers: 10, clearance between steel two rollers: 10 mm, width of feeder inlet: 162 mm, steel roller long axis diameter: 20 mm, number of spoke plates: 5. In conclusion, the above reverse design process provides a systematic design method for the key parameters of steelroll round balers, which has important guiding significance for the design of steelroll round balers.

In order to meet the needs of variable spray technology for boom sprayers, a variable spray control and test bench for boom sprayers were designed to realize real-time control and performance testing of existing variable spray devices. The variable spray control and test bench are composed of a control system and a data acquisition system. The control system is based on Siemens S7-200 series PLC, which is composed of a power system, drive system, flow system, and variable control system. The data acquisition system uses data acquisition modules and sensors to obtain pipeline flow, pressure, torque, driving speed and other parameters. Real-time display and storage of the collected parameters can be achieved through LabVIEW software. The flow accuracy test under the speed condition shows that the average flow error is 4.0%, which can be used as a technical reference for judging the performance of the variable spray device. The test shows that the test bench can effectively control the variable spray control components of the boom sprayer in real-time to meet the requirements of the boom sprayer. The performance test requirements of variable spray control components of sprayers provide technical reference for the formulation of technical specifications for variable spray quality evaluation.