Development of CAD system for combined machine tool fixture

2022-09-06 13:04:14
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With the maturity of CAD technology, CAD has been used more and more widely in various production fields. The elimination of the drawing board and the comprehensive promotion of applied CAD technology have been listed as the top priority of the national “Ninth Five-Year Plan”. At the same time, the "Ninth Five-Year Plan" will take the automobile industry as the pillar industry of the national economy, and the combination machine tool industry that provides technical equipment to the automobile industry will also be rapidly developed. The combined machine tool is a one-piece production of one-off design and one-time manufacturing. The structure is varied, the design is large, and the design work is complicated. Especially in the current highly competitive market economy, the user's technological advancement and quality of the machine tool. The reliability and delivery cycle are very demanding, and the traditional backward manual design methods can no longer meet the requirements of current product design. The combination machine tool system adopts CAD technology, and it is imperative to replace the traditional design method with modern design methods.

In April 1997, we undertook the Dalian Science and Technology Key Project: "Development, Expansion, Transplantation and Commercialization of Combined Machine Tool CAD System". The main task was to design a CAD system software for combined machine tools. The combined machine tool fixture CAD system is part of the whole system, including the general fixture CAD system, the combined machine tool fixture CAD system and the combined machine tool fixture design manual.

The fixture is an important component of the combined machine tool and is specifically designed according to the specific requirements of the machine tool's process and structural scheme. It is used to achieve accurate positioning of the machined parts, clamping, tool guiding, and limit when loading and unloading the workpiece. Whether the layout is reasonable or not directly determines the success or failure of the combined machine tool production. However, looking at the domestic market, there is currently no perfect fixture CAD system for designers to use, especially the combined machine tool fixture CAD system. There are still some difficulties and problems in the application of foreign fixture CAD in China. First, the issue of funds, foreign CAD software prices are relatively high, most domestic manufacturers are difficult to pay such expensive costs; Second, China's combined machine tools have their own standards, foreign CAD software does not match the domestic standards, bringing great design difficult. All these factors have strengthened our determination to design fixture CAD with its own characteristics.

2 system overall design

1. Software design ideas

    This system is a combined machine tool fixture CAD software based on the current world's most popular basic support software AutoCAD R14.0 on the microcomputer platform. Because the design of the combined machine tool fixture is very specific, if the automatic design is used, only the CAD software of the combined machine tool fixture design can be completed by inputting only a few parameters, the application is small and has great limitations. The system uses a combination of parametric design and interactive design. The parametric design completes the design of the product structure by inputting some parameters by the user; the interactive design is performed by the user, interactively selecting components, and determining the model. In this way, the design of the product versatility is realized by the computer, and the design of the product specificity by the user by means of the computer avoids the limitation of the versatility of the automatic design and the narrow design.

This system uses Windows 95/98, Windows NT4.0 Pentium microcomputer as the development and operation platform, based on AutoCAD R14.0 as the support software, using FoxPro 2.5 to build the database, comprehensive use of dynamic data exchange technology DDE, graphics software secondary development Technology ADS/ARX, an interactive graphics processing software developed in the Microsoft Visual C++ 5.0 build environment.

2. System platform construction

Before developing a system, it is especially important to choose the right hardware platform and software environment based on the actual situation of the current enterprise.

In the promotion of CAD applications, many companies adopt a high starting point and a one-stop approach to workstations. However, computer hardware is developing rapidly. Two or three years have taken a leap. Some enterprises have bought expensive workstations, which have been eliminated after they have been used, resulting in waste. With the popularity and performance of microcomputers, CAD/CAM systems based on Pentium, Pentium Pro and Pentium II microcomputers will become mainstream. In the promotion and application of CAD, “useful, sufficient, practical” is still the most important. The CAD technology with microcomputer as the hardware platform is generally suitable for the current situation of China. (Of course, this does not mean that traditional workstations will become more and more Micro-type, in the product modeling, 3D simulation, etc. still need high-performance workstations to complete).

For the operating system, Windows 95/98/NT is the best choice. The DOS system has been eliminated by the CAD software, and should not continue to use this backward operating system because it is familiar with DOS. UNIX was a must for CAD software a few years ago, because only UNIX was a 32-bit operating system at the time, and it could play the role of CAD software. Windows 95/98/NT is now a mature 32-bit operating system. From the perspective of functions and user groups, choosing a Windows operating system is an inevitable trend. This kind of system has the advantages of good performance, friendly interface, simple and convenient maintenance, etc. It can work alone, and the network is also very convenient. Its performance can fully meet the needs of enterprises. Another outstanding advantage is the ability to fully integrate CAD/CAM applications with general office software to take full advantage of the Windows standard platform.

3. Support software selection

Secondary development is different from general software development, mainly because it is not a software design starting from the bottom, but a development on existing software, so the biggest feature of secondary development is inheritance. The software function after secondary development depends to a large extent on the function and openness of the supporting software itself. Therefore, the choice of supporting software is critical.

First of all, the software should be produced by a large, large-scale company to prevent the loss of long-term and technical support due to the collapse of software components.

Secondly, you should choose software that you are familiar with and that is constantly improving. Full-featured, excellent performance; with standard graphics format, easy to exchange with other software, in line with international and domestic standards; with Windows95, Windows NT and workstations and other versions, support a variety of hardware platforms from microcomputer to workstation, to achieve full functionality The same, and seamless integration on the network and data.

Finally, and the most important performance is the ability to support the openness of software, or secondary development. It can be considered from two aspects: on the one hand, whether the development function is complete, whether the interface is simple; on the other hand, whether the development language is a general-purpose high-level language, and whether the compilation environment is excellent.

AutoCAD R14.0 is Autodesk's latest auxiliary design software. It is a universal interactive drawing software with the largest number of users in the world and the largest number of domestic users, accounting for more than 70% of the microcomputer CAD market. AutoCAD is an engineering and commercial software. It has high reliability, fault tolerance, stability and hardware compatibility. It is fully functional, easy to use, high in performance and price, and has very good openness. Called the default "global standard", it is the best choice for supporting software.

3 system main function module

The combined machine tool fixture CAD system is a parametric graphical information management system software for the combination machine tool designer. It integrates the database operating system and the parametric graphics system, enabling the designer to remove the drawing board and remove the manual for design. The software mainly includes four modules: general mechanical CAD system, universal fixture CAD system, combined machine tool special fixture CAD system and combined machine tool fixture manual. The general mechanical CAD module is the basic module. The architecture of the combined machine tool fixture CAD system is shown in Figure 1.

1

In order to develop the CAD system of the combined machine tool, we first developed a set of general mechanical CAD system based on AutoCAD. The main contents include: adding Chinese menu, Chinese character labeling, suitable for national standard dimensioning, geometric tolerance labeling, standard parts library And the establishment of common parts library, size drive, intelligent design of typical parts and other modules. It provides a prerequisite for the realization of a combined machine tool fixture CAD system.
The general mechanical fixture CAD system establishes the graphic library, database and program library of positioning parts, support parts, guiding parts, clamping parts, operating parts, etc. according to the design requirements of the latest national standard mechanical coils, using interactive design methods. Achieve no manual design.
The CAD system of the combined machine tool special fixture establishes the following modules according to the industry standard of the combined machine tool: CAD of the positioning support system; CAD of the clamping mechanism; CAD of the guiding device; computer-aided analysis and calculation of the clamping force of the typical clamping mechanism. Each module establishes a graphics library, a database, and a program library, and implements the design by using an interaction design method.
In addition, a manual manual for machine tool fixtures has been established. The standard drawings of various types of standardized machine tool fixtures are built in the form of DWG, which can be easily inquired or slightly modified to form the user's own special fixture mechanism.

4 system environment configuration

  1. Software development environment
    1. Hardware environment
      • Host CPU Pentium MMX 166
      • Memory 64M EDO
      • Hard disk Seagate 4.3G
      • Optical drive Sony 8 times speed
      • Floppy drive 1.44M
      • Display EMC SVGA 15" color display resolution 1024 × 768
      • Printer Canon BJC-4550
      • Plotter Houston DMP-162 Drum Plotter
    2. Software Environment
      • Operating system Microsoft Windows 95/98, Windows NT4.0
      • Support software AutoCAD R14.0
      • Compiler Microsoft Visual C++ 5.0
      • Database software FoxPro 2.5
  2. Software operating environment
    3. Requires PC486, 586 and Pentium microcomputers, with SVGA card and graphic display with resolution of at least 800×600. It is recommended that the CPU frequency be above 100MHz and the memory is above 32M. It is equipped with any type of printer, plotter and mouse. The system is pre-installed with Windows 95/98 or Windows NT4.0 operating system, and pre-installed with AutoCAD R14.0 basic software. The entire fixture CAD system requires the remaining space of the hard disk to be more than 150MB.

5 system installation and operation

This system must be installed on a hardware platform with Windows 95/98 or Windows NT as the operating system and pre-installed with Autodesk's AutoCAD R14 software.
This system installer is built with InstallShield 4.2 and has a standard Windows style. When installing, run the setup.exe on the CD or the first floppy disk, and follow the installer prompts to complete the installation step by step.
After the installation is complete, find the APCAD R14 icon created by the installer in the program item of the Windows Start menu. Double-click the icon, the system will call the Apcadr 14.exe file in the installation path to complete the system registration and path setting, and automatically Search for the AutoCAD R14 program file to launch AutoCAD R14. The second time you enter the system, you only need to run AutoCAD R14 directly.
The system was approved on December 15, 1998 by an expert meeting organized by the Dalian Municipal Science and Technology Commission. The participating experts gave high praise to the results of the project and agreed that the results are at the domestic leading level.
Today, the system has been released domestically as commercial software. Because the modules of the system are relatively independent, the user can select one or more of the modules, but the general mechanical CAD system module is the basic module of the system and is the prerequisite for running other modules. In order to cooperate with the CAD application project being implemented by the State Science and Technology Commission, to help enterprises to “scratch the board” as soon as possible, and to promote the popularization and application of CAD, we have made the general mechanical CAD software into two versions, one is the commercial software, which is issued to the whole country. A dongle is required to run; one is teaching software, is not encrypted, and has most of the features of the previous version, especially suitable for school use. Today, the teaching version of the software has been widely used in the drawing and teaching research and computer room of the Mechanical Department of Dalian Railway Institute.
Since the issuance of the CAD system software of the combined machine tool, it has been recognized by many domestic enterprises. The general mechanical CAD system software has won the favor of users with its attractive price, friendly interface and convenient and easy to learn. At present, many companies in China have used the software and have achieved good economic and social benefits.

6 Conclusion

This system is a CAD software for 2D design. It is friendly, flexible, applicable and practical. It is a powerful tool for mechanical designers, especially for combination machine designers.
As far as the situation of most domestic enterprises is concerned, the traditional hand-work diagram method is basically used, and the efficiency is extremely low. CAD drawing technology can greatly improve the design efficiency and quality, the drawings are easy to modify, and the sharing of graphic data can be realized. Easy to manage. Even if 3D CAD is popularized in the future, it is essential to make 2D drawings. Especially in the early stage of the full application of CAD in China, this system is very practical and effective for the majority of enterprises to get rid of the board and promote the application of CAD technology. Of course, this topic will continue to do a lot of follow-up work, such as continuing to develop software such as finite element analysis, 3D modeling, CNC machining, simulation, etc., which requires finding more reasonable 3D design tools to make CAD, CAE, CAPP, CAM and PDM. Melt into one.

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