Research On The Digital Design Technology Of Z-Model Combine Harvester's Key Parts

The traditional design method was replaced by the modern design method gradually with the development of the compute technology in the recent years. The digital design technology not only include the new technology of modern design but also is the precondition of it. The research on the digital design technology is more important to the engineering. The quantity of agricultural equipment in our country increased steadily and the working level improved step by step. The great development of the mechanization of farming enhanced the working productivity and heightened the integration throughput, quickened the transformation from the traditional agriculture to the modern agriculture. However, there are some question in the mechanization of farming development, for example, the level is low in a whole, development is lopsided, the quality is not good and so on. Agricultural equipment made in our country was followed behind the developed country's in the technical level and the product's structure. This was bring by the product's design level. In this paper, the digital design technology was introduced in the agricultural machine industry, the design method changed from the traditional to the modern and the digital design level of agricultural machine was enhanced. The competition advantage centralized the design.We take combine harvester's key parts as example discussed the technology relative digital design and it's application in the engineering. The content of which is the trend of modern product development, namely, digital, parallel, intelligentized and integrated. The digital product development was discussed in this paper which include digital product definition, digital pre-assembly, digital simulation and the digital manufacture.The process from the product concept to project perfect is subdivision. The design project was perfected frequently in this process until it meet the request. The product modeling was done utilized parametric geometry modeling technology in the process. It is different to the traditional geometry modeling technology, the product model included a lot of non-geometry information, so the produce model method based feature was adopted. The parametric modeling technology based feature was researched in this paper, and the product digital model software, Pro/Engineer, was selected and it's modeling mechanism was dicussed.The digital modeling technology was researched in this paper. Three modeling mode of entity which is wireframe model, surface model and solid model was discussed, and the surface model, feature-based modeling and parametric modeling were discussed too. The Pro-Engineer was selected as the digital product modeling support plat. Feature-based modeling that used feature describing method and the family-table method provided by the Pro/Toolkit and parametric modeling programming were researched in this paper.The compute supported system structure of design for assembly was researched. The Top-down design pattern of design for assembly system was discussed in the parallel environment. The Top-down design of combine harvester's key parts was completed using the top basic skeleton. The conflict type was definitude in the case of cutter digital assemble of combine harvester. The main part was introduced and conflict correspond rule based assemble relation was built in development process. The product re-design was gained by intervene analysis and appraise module, and the product design process was perfect more. At the same time, the parts database was built.The application of finite element analysis to engineering was discussed based on the researched the digital simulation's basic step. The digital simulation of threshing unit was done. The scientific conclusion was gained by trimming and analyzing the data of simulation results. The visual technology was adopted in the modern simulation software, the state of the simulation object was showed by figure, diagram and cartoon. The output information of simulation is abundance and large which is propitious to analyzing of the simulation results.At last, applying the digital design technology into the combine harvester was researched. The digital modeling and virtual assembly of combine harvester parts as the cutter, threshing unit, the promoting and discharged equipment and so on were completed. The simulation, analysis and optimization of the combine's key parts as frame of cutter table, cutter and so on.. The cutter's inspirit frequency to the frame of cutter table is lower then the frequencies itself when combine run in the working condition, so the sympathetic vibration will not happen and the frame of cutter table will not be destroyed. The movement parameters of the cutter will gain utilized the software ADAMS. The position, velocity and acceleration were measured in the movement process of cutter and gained the parameters of them. It can be seen from that the position, velocity and acceleration was function of time, and movement rule is sinusoid or cosine. The velocity of cuter is maximal and the acceleration is minimum in the middle of journey. The movement of cutter is not symmetrical and the reciprocate trochoid is not same. The velocity and the acceleration of cutter is changing in the journey and the velocity is the elliptical function of position, which come to a head in the middle of it. The acceleration is the linear function of position, it come to head at beginning and end and touch bottom in the middle of it. The result of simulation accord with the theoretics analysis and answer for design request.This paper completed under the supported by national natural science foundation of China "the new technology of digital design and system design of combine harvester" (No.50575221). Some of the data and diagram in this paper come from the researching of it. The research production have directive significance in the others agricultural machine products' development.