Due to the crisis of aging population and the sharp decrease of agricultural labor force, China attaches more and more importance to the development of agricultural machinery. However, there are many kinds of agricultural machinery, and the production batch is small. As a key part of agricultural machinery, gear is complex and difficult to model, there are a lot of repeated design work, which seriously affects the research and development cycle of agricultural machinery. The key to the sustainable development of agricultural machinery is to introduce modern design methods such as knowledge engineering, 3D reconstruction modeling and virtual simulation to improve the intelligence and automation of agricultural machinery product design in China.
Knowledge engineering is the basic theory of virtual design. In recent years, many organizations at home and abroad have carried out in-depth research on knowledge engineering, and achieved a series of important results. Agricultural University of China has carried out a lot of work on intelligent agricultural machinery and equipment, and established key model knowledge base such as crawler tractor. Zhejiang University has developed the intelligent fixture design system, and put forward the knowledge representation and reasoning method of fixture design based on ontology. South China Agricultural University applies 3D reconstruction to product knowledge modeling, and studies the virtual simulation system of picking manipulator. Reddy and others developed a knowledge-based parametric modeling system for cylindrical gears, which greatly reduced the time of gear design and calculation. Yin et al. Proposed a knowledge recommendation method based on forgetting curve, which helps engineers improve design efficiency and quality by recommending applicable knowledge. CATIA and NX, three-dimensional software companies, have developed knowledge engineering design modules such as knowledge engineering experts and knowledge fusion, and achieved good results.
In the process ofvirtual design and simulation, there are many gear models and low knowledge reuse rate, which affect the research and development cycle of the whole machine. In order to improve the level of intelligent design of agricultural machinery, this paper takes the design of tractor gearbox as an example, applies the methods of knowledge engineering and parametric design to the virtual design of gears, develops the virtual design system of gearbox gears based on knowledge, and verifies the feasibility and effectiveness of this method through an example.
Taking the tractor gearbox as an example, the virtual design method of gear based on the combination of knowledge engineering and parametric design technology is studied, and the knowledge acquisition related to gear design is completed, and the knowledge representation methods such as production and ontology are used to express, so as to realize the reuse of gear design knowledge. By using NX secondary development technology, gear structure intelligent selection and virtual design are realized in NX system, which can better support the virtual design and Simulation of gearbox, and verify the feasibility of this method. The design system inherits and reuses the mature design knowledge of gear, reduces the design time while ensuring the accuracy of gear modeling, and provides reference for the virtual design of other mechanical products.