1 Domestic and foreign research overview, level and development trend
Due to its irreplaceable performance features such as simple structure, strong process adaptability, and low environmental pollution, hydraulic presses are widely used in the national economy of automobile manufacturing, aerospace, defense, power electronics, plastics, machinery, metallurgy, and light industry. each field. According to incomplete statistics, the number of design departments and production plants that use hydraulic presses as main products in China has reached 100, but the application of CAD is disappointing. The overall technical level of the hydraulic press design and manufacturing industry lags far behind that of industrialized countries, making the contradiction between the fierce competition in the international market and the backward design level in China increasingly acute. Specifically in the following aspects:
1.1 Design Methods Domestic major design units of hydraulic presses, including some major design institutes of the leading design institute of the First Heavy Machinery Group Corporation, still have their design work based on drawing operations, and the design work is good or bad. It depends entirely on the technical quality and working conditions of the designers. Therefore, the design quality (including the rationality of the structural design, the accuracy of the design data, etc.) and the design efficiency are low and the design cycle is long. At the same time, the backward design methods have also brought a lot of inconvenience to the quotation work, such as the long preparation time of quotation books and the large deviation of quotation. All of these influence the competitiveness of a company to varying degrees.
1.2 Analytical theory In the past decade or so, although some of the conditional design institutes have been able to perform some finite element structural analysis on the key components of the hydraulic press, due to the backward design methods, these analysis results have not been able to play a role in the design. Due role. Therefore, the analysis of strength, stiffness and overall work performance in the design of the hydraulic machine body is still based on the mechanics of the material, even with experience and intuition. With material mechanics to solve such complex practical problems, the space problem has to be reduced to a plane problem, which greatly deviates from the actual situation. For this reason, people have to reduce the allowable intensity of the material and sacrifice the structural rationality in exchange for the safety of the structure. Because of the relatively low technological content, compared with similar products in Japan, it appears that a device with a large structure, bulkiness, and the same ability has a weight that is generally 10% to 20% higher. And its cost competitiveness is completely at a disadvantage.
1.3 Appearance Forming equipment appearance and shape problems have only attracted people's attention in recent years and have just formed a sense of consciousness in the minds of designers. Due to the lack of physical means, this awareness can only eventually become a designer's personal behavior. Designers are each in their own right, and their actions are simply not to be used to shape the style and characteristics of a company. The appearance of the product lacks scientific and artistic considerations and is an important factor in the lack of competitiveness of the product.
2 The meaning of the hydraulic machine body CAD system
With the deepening of the CAD industry in the mechanical industry, the vast majority of hydraulic press design institutes and manufacturers have also done a lot of work in this regard, laying the foundation for realizing true CAD. However, as far as the current CAD application is concerned, the following two problems remain: First, the slow progress of CAD work and the fragmented results make it difficult to give full play to its advantages. The software purchased by several large institutes from abroad is mainly used for finite element analysis. As a CAD platform, there are few secondary development tasks. The level of software development is not high, and the application is too targeted and the application is limited. Second, most of the existing CAD software has difficulties in interaction and inconvenience in the user interface, which greatly limits the promotion and application of CAD technology.
To face the 21st century, if companies want to survive and develop, they must effectively master advanced productivity and establish a strong sense of market, cost, and efficiency. Development and design of products must also meet user requirements for variety, batch, time, and quality. Therefore, based on technical and economic indicators such as process usage, manufacturing cost, machine performance, etc., it is possible to flexibly modify the design scheme, timely analyze the structural performance, accurately evaluate the function and behavior of the complete machine or critical part, optimize the structural parameters, and provide high quality for manufacturing. The high-level set of technical data is the goal pursued by the machinery manufacturing industry at the present stage and is the driving force behind the rapid development of CAD technology. Today, whether to master CAD application technology has become an important indicator of whether a company can enter the information age. CAD has been recognized as one of the effective technologies and methods to improve the ability of enterprises to participate in competition.
The CAD technology of the Fusion Expert System (ES) relies on the knowledge and experience of experts, solves the technical design problems in the field with the level of human experts, and makes the design process intelligent. This is undoubtedly a revolution in design methods. Although the introduction of expert systems into mechanical design has only a short history of more than a decade, MED has inspired a large number of companies because it provides detailed, reliable, standardized, and efficient design basis for modern mechanical design. The application of enthusiasm. Based on the expert system and the microcomputer-oriented hydraulic machine body CAD system, it is expected that the hydraulic press body design technology will be improved from the backward drawing board operation level to the modern design advanced level. The development of this advanced technology will improve the backwardness of China's hydraulic press design and manufacturing industry, promote the progress of the national industry, realize the optimal design of hydraulic products, shorten the design and development cycle, improve the quality, and enhance the competitiveness of companies in the international market. It is of great significance for China's hydraulic press manufacturing to gradually realize CAD/CAM integration.
The main task of this dissertation is to realize the intelligentization, parameterization, data standardization and commercialization of the hydraulic machine body design, and to provide an easy-to-use Chinese-language user interface with a plot rate of more than 90% of the total drawing volume.
3 Hydraulic Machine Body CAD System
The hydraulic machine body design CAD system mainly includes three modules: the body design expert system YYJES1.0, the body discrete optimization software YKJU3.0 and the ontology parameterization drawing software.
Expert system is an application area of ​​artificial intelligence. In order to realize the intelligentization of hydraulic machine body design CAD system, it is necessary to establish an expert system for hydraulic machine body design. Ontology design expert system is composed of knowledge base, database, human-machine interface and inference engine. Its block diagram is shown in Figure 1.
Figure 1 Structure of Expert System
The main object of the optimized design of the hydraulic machine body part is the two beams of the hydraulic press, namely the upper beam and the lower beam (base). The purpose of the optimization design is to make these components to be lightest by adjusting the thickness of each plate under the premise of meeting the design requirements of strength, stiffness, etc. The optimization algorithm used is the SPG method. SPG method is a structural discrete optimization algorithm that combines sequential quadratic programming (S), penalty function (P) and genetic algorithm (G). The SPG method can well solve the discretization of large structures such as the hydraulic machine body.
The parametric drawing module uses AutoCAD as a platform and uses advanced ADS technology for secondary development. Can output posts, bases, upper beams, live beam parts drawings, and body outline drawings.
Based on the expert system and discrete optimization of hydraulic machine ontology CAD system block diagram shown in Figure 2.
Figure 2 YYJCAD1.0 flow chart
YYJCAD1.0 is easy to use and easy to operate. The user only needs to input the main technical parameters and formal parameters of the hydraulic press. The system can automatically complete the body optimization design and can output all parts of the body diagram.
4 Conclusion
This paper lays the foundation for realizing the intelligentization and modernization of hydraulic press body design through the development of hydraulic machine ontology CAD system based on expert system and discrete optimization. A framework of hydraulic machine body CAD system, which is supported by expert systems, is based on modern design theory and methods, and uses AutoCAD as a drawing platform, is basically formed.