Development Of Parametric Design System For Threshing And Cleaning Device Of Combined Harvester Based On Knowledge

With the continuous upgrading of global industry,the competition of agricultural machinery equipment manufacturing industry is increasingly fierce,and the market demand becomes more diversified.Compared with the western developed countries,the design and development methods of agricultural machinery equipment manufacturing industry in China are still insufficient,resulting in long design cycle,low efficiency and poor design reliability.Therefore,it is very important to establish a knowledge-based parametric design system for agricultural machinery equipment manufacturing enterprises to improve their independent design and development capabilities by using the existing design knowledge and integrating the characteristics of actual product examples.Combine harvester is one of the most important agricultural machinery equipment,threshing and cleaning device as its core operation device,the study of its knowledge-based parametric design system has important practical significance.The design and manufacturing process of threshing and cleaning device involves a lot of design knowledge such as design formula,rules,experience and design examples.The traditional design and development method have a long design cycle and low design efficiency,whether meet the current market demand.In order to break the limitation of traditional design and development methods,reduce repetitive design,improve design efficiency and reduce design cost,this paper uses knowledge engineering and parametric design technology to develop a knowledge-based parametric design system for threshing and cleaning device of combine harvester.The specific research content is divided into the following parts:(1)Construction of knowledge base for threshing and cleaning deviceAt the initial stage,the design knowledge is mainly acquired manually.After the design system runs,the design knowledge of combine harvester threshing and cleaning device is acquired manually and automatically;the design knowledge acquired by classification is mainly divided into case class and rule class knowledge;the corresponding knowledge representation method is determined according to different types of design knowledge;the design knowledge is stored in the In the database SQL Server software,the knowledge base of the threshing device of the grain roller type,the nail tooth roller type,the double drum type,the axial flow roller type and the bow tooth roller type,as well as the fan vibration screen type,the air flow type cleaning device knowledge base,provides the knowledge foundation for the knowledge reasoning of the design system.(2)Construction of parameterized model library of threshing and cleaning deviceThe parametric design interactive interface of threshing and cleaning device model instance is created by UIStyler and PTSAuthor tools in NX;Taking the parameterization of nail-tooth threshing cylinder model as an example,the model examples and corresponding expressions of elbow nail-tooth,tooth plate,spoke plate,grass-discharging plate,reinforcing ring and cylinder transmission shaft of nail-tooth threshing cylinder are created by using NX expression technology,and the parametric modeling program is written to realize the parametric design of nail-tooth threshing cylinder model examples Parametric modeling was carried out for each part model instance of five main threshing devices and two cleaning devices in the knowledge base,and then 702 parameterized part model instances were stored in NX reuse library and imported into Teamcenter.The parametric model library of threshing and cleaning devices corresponding to the instance knowledge in the knowledge base was constructed,which greatly shortened the design cycle of threshing and cleaning device models.(3)Construction of parametric design system for threshing and cleaning device based on knowledgeThe ADO.NET interface method is used to integrate the knowledge base of the threshing and cleaning device constructed with Visual Studio,and the window application program of the parametric design system of the threshing and cleaning device based on knowledge is developed by Visual Studio,which realizes the design system The function of adding,modifying,deleting and querying design knowledge in the knowledge base;researching the case-based knowledge reasoning method combining complete machine-device instance matching and nearest neighbor similarity algorithm,and developed knowledge-based threshing and cleaning in Visual Studio The parameterized design system of the device;taking the example of outputting the nail-tooth threshing drum model as an example,the design system is tested,and an example of the nail-tooth threshing drum model that meets the design parameter requirements is inferred,which proves the feasibility of the design system.Through the knowledge-based parametric design system of threshing and cleaning devices,the design efficiency of threshing and cleaning devices can be improved.(4)Simulation analysis and prototype testThe static analysis and modal analysis of the nail-tooth threshing drum model example output by the system test are carried out,and the strength and rigidity of the output nail-tooth threshing drum model instance are determined to meet the requirements;this is completed on the basis of the output nail-tooth threshing drum The parameterized and modified design of the entire model example of the nail-tooth drum threshing device,and the prototype is manufactured;through the bench test of the rotating speed of the prototype drum,the designed output of the nail-tooth drum threshing device is determined,and the drum speed is650～950r/min,a good threshing effect with a total loss rate of less than 3% and a crushing rate of less than 1.5% can be obtained,and when the speed is 850r/min,a total loss rate of0.83% and a crushing rate of 0.15% can be obtained.The optimal threshing effect is consistent with the optimal drum speed required by the design parameters,which proves that the designed output spike drum threshing device meets the design parameter requirements.Through the simulation analysis and bench test of the design examples,the effectiveness and practicability of the knowledge-based parametric design system for threshing and cleaning devices are proved.