The Current Situation and Development of Hydraulic Press Body CAD
1 Domestic and Foreign Research Overview, Level and Development Trends
Due to their unique advantages such as simple structure, strong process adaptability, and low environmental impact, hydraulic presses are widely used in various sectors of the national economy, including automobile manufacturing, aerospace, defense, power electronics, plastics, machinery, metallurgy, and light industry. According to incomplete statistics, over 100 design departments and production plants in China use hydraulic presses as their main product. However, the application of CAD technology remains limited. The overall technical level of the hydraulic press design and manufacturing industry lags significantly behind that of industrialized countries, creating an increasingly acute contradiction between fierce international competition and China's outdated design capabilities. This situation manifests in several key areas:
1.1 Design Methods
Major domestic design units, including some leading institutes under the First Heavy Machinery Group Corporation, still rely on traditional drawing-based methods for hydraulic press design. The quality of the design—such as structural rationality and data accuracy—largely depends on the expertise and working conditions of individual designers. As a result, the design efficiency is low, the cycle is long, and the quality is inconsistent. Moreover, outdated design methods also cause issues in quotation work, such as extended preparation times and significant deviations in cost estimates. These problems directly affect the competitiveness of companies in the global market.
1.2 Analytical Theory
Although some research institutes have conducted finite element analysis on critical components of hydraulic presses in recent years, these results are not effectively integrated into the design process due to outdated methodologies. As a result, strength, stiffness, and performance analyses are still largely based on classical material mechanics, which often simplifies complex 3D problems into 2D models. This approach leads to inaccurate predictions and forces engineers to reduce material strength or compromise structural rationality for safety. Compared to Japanese counterparts, Chinese hydraulic presses tend to be heavier by 10–20%, resulting in lower cost competitiveness.
1.3 Appearance and Forming
Only recently have appearance and shaping of hydraulic presses begun to attract attention, with designers gradually developing a sense of aesthetic awareness. However, this awareness is still limited to personal preferences rather than systematic design principles. As a result, product aesthetics lack scientific and artistic considerations, further weakening the competitive edge of Chinese hydraulic presses in the global market.
2 The Significance of Hydraulic Press Body CAD Systems
With the deepening of CAD technology in the mechanical industry, most hydraulic press design institutes and manufacturers have made efforts in this area, laying the foundation for full-scale CAD implementation. However, current CAD applications still face challenges. First, progress is slow, and results are fragmented, limiting the full potential of CAD. Many large institutes use foreign software primarily for finite element analysis, with limited secondary development and narrow application scope. Second, existing CAD software often suffers from poor user interaction and inconvenient interfaces, hindering widespread adoption.
To survive and grow in the 21st century, companies must embrace advanced productivity and develop a strong market, cost, and efficiency mindset. Product design must meet diverse, timely, and high-quality user demands. Therefore, it is essential to flexibly modify design schemes, analyze structural performance, evaluate machine behavior, optimize parameters, and provide high-quality technical data. These goals drive the rapid development of CAD technology. Mastering CAD is now a crucial indicator of whether a company can enter the information age. It is also recognized as a key method to enhance enterprise competitiveness.
CAD technology based on expert systems (ES) leverages the knowledge and experience of experts to solve complex design problems at the level of human experts, making the design process more intelligent. Although expert systems have only been introduced into mechanical design for over a decade, they have inspired many companies by providing detailed, reliable, and efficient design support. A CAD system combining expert systems and microcomputer technology is expected to elevate hydraulic press design from traditional drafting to modern, intelligent levels. This advancement will address China’s backward design and manufacturing industry, promote national industrial progress, enable optimal design, shorten development cycles, improve quality, and enhance global competitiveness. It is vital for China’s hydraulic press industry to gradually achieve CAD/CAM integration.
3 Hydraulic Press Body CAD System
The hydraulic press body CAD system consists of three main modules: the body design expert system YYJES1.0, the discrete optimization software YKJU3.0, and the ontology parameterization drawing software. An expert system is an application of artificial intelligence, designed to mimic human expertise in solving technical design problems. To realize intelligent design, an expert system for hydraulic press body design must be established. This system includes a knowledge base, database, user interface, and inference engine, as shown in Figure 1.
Figure 1: Structure of Expert System
The main focus of the optimized design of the hydraulic press body is its upper and lower beams. The goal is to minimize weight while meeting strength and stiffness requirements. The SPG method, a combination of sequential quadratic programming, penalty function, and genetic algorithm, is used for structural optimization. This method is effective for large-scale structures like hydraulic presses.
The parametric drawing module uses AutoCAD as a platform and incorporates ADS technology for secondary development. It can generate drawings for posts, bases, upper beams, live beams, and overall body outlines.
Figure 2: Flow Chart of YYJCAD1.0
YYJCAD1.0 is user-friendly and easy to operate. Users only need to input main technical and formal parameters, and the system automatically completes the body optimization and generates all necessary drawings.
4 Conclusion
This paper lays the groundwork for achieving intelligent and modern hydraulic press body design through the development of a CAD system based on expert systems and discrete optimization. A framework for a hydraulic press body CAD system, supported by expert systems, modern design theories, and AutoCAD as a drawing platform, has been basically established. This advancement marks a significant step toward improving China’s hydraulic press design and manufacturing capabilities.
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