Research on the application of Integrated DNC tech

2022-07-26
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Research on the application of Integrated DNC technology based on local area computer integrated manufacturing system (CIMS), as a mode for enterprises to organize production activities, has been greatly developed in modern manufacturing engineering. At present, cad/cam+dnc, cad/cam+fms, cad/cam+mis and other different modes are more popular. In cad/cam+dnc mode, DNC (direct numerical control) system plays an important role as a key link connecting the preceding and the following in this mode. Since most manufacturing enterprises have established their own NT local area in the process of realizing informatization, the Integrated DNC technology based on NT local area has been rapidly developed and applied

in the process of building the computer integrated manufacturing system, Xuchang Tobacco Machinery Co., Ltd. has established and improved the cad/cam/capp system, purchased a variety of NC processing equipment, established a NC workshop, and established NT local area and ERP systems in the process of enterprise informatization. However, the management of NC machining program of parts adopts decentralized management, and the data exchange with NC machining equipment adopts indirect transmission with floppy disk as the carrier. These directly lead to poor security of NC program, low accuracy and efficiency of transmission, and are difficult to meet the requirements of integrated manufacturing system, which has become the bottleneck of computer integrated manufacturing, so it must be solved. As Xuchang Tobacco Machinery Co., Ltd. has a relatively mature NT local software and hardware foundation, it has the material and technical conditions to build a DNC System Based on NT local area

I. Analysis of equipment performance and control characteristics in NC workshop

1 There are various CNC systems. When the oil delivery valve is opened smaller, the CNC processing equipment of Xuchang Tobacco Machinery Co., Ltd. is purchased from different countries in different periods. The CNC systems include FANUC, Siemens, Hyde Heine, Toshiba and other brands. Even if the same CNC system has multiple versions, that is to say, the CNC system of the company has diversity

2. Perfect data interface of NC processing equipment

Xuchang Tobacco Machinery Co., Ltd. fully considered the foresight of network technology development when purchasing equipment. All kinds of NC equipment are equipped with floppy disk drive or RS-232 interface for data exchange between NC processing equipment and the outside

3. The processing procedures are complex and diverse

at present, the company has more than 1080 types of parts processed by various CNC equipment, accounting for 27% of the machined parts of the products, and most of them are the main key parts of the company's products. The complexity of machining parts and the diversity of CNC system determine that the same part may have multiple machining programs or the machining program is long, which brings about program management and transmission. 1. Self locking: certain difficulty

4. Program management before the establishment of DNC system

since the DNC system has not been established, the transmission of NC programs takes floppy disk as the medium, and the transmission accuracy, reliability and efficiency are very poor. The processing program of complex parts is long, one transmission cannot be completed, and multiple segmented transmission is required, which is easy to cause multiple transmission, less transmission and false transmission of data

to solve the problems of safety, accuracy and timeliness of transmission of NC machining program management, DNC technology is a better solution. Based on the company's existing network foundation and the characteristics of CNC processing equipment, we adopted the Integrated DNC technology based on NT local area and established the ExtremeDNC (super DNC) system

II. Network structure of the ExtremeDNC system

through the analysis of the performance and control characteristics of the company's NC workshop equipment, we decide that the ExtremeDNC system adopts the client/server network structure management mode, simulates each NC processing equipment as a client device, and uses the RS-232 interface and communication function of the digital control system to directly control the NC processing equipment. The network structure of the system is shown in Figure 1

Figure 1 system structure diagram

III. ExtremeDNC system features and functions

1 High reliability

extremednc system can meet the continuous and reliable control of multiple sets of equipment in the NC workshop and the requirements of continuous production of multiple sets of equipment. The system can control the two-way sending and receiving of NC files of up to 256 NC machining equipment at the same time

2. Breakpoint continuation function

extremednc system has breakpoint continuation function, that is, data is transmitted from the tool breaking point. This function is very important for data transmission of CNC machine tools with small memory and very large part programs (such as mold processing)

3. Remote control function

the operator of the machine tool can directly call data from the DNC server through the controller or send the data in the controller to the DNC server, so as to realize the two-way transmission of data in different places. Users can define different remote request commands according to different controllers to realize the remote control function

4. Powerful file management function

extremednc system adopts an open structure for file management, and can infinitely call third-party application software, such as word, Excel or database software. Each CNC machine tool has corresponding outbox and inbox directories, which can avoid file confusion and overwriting. At the same time, specific network search paths are defined for different machine tools, so that the machine operator can directly call the required data from the network or send the machine memory data to the DNC server, and automatically save it to the specified network security directory. ExtremeDNC system also has the function of NC file version management, which compares the old and new version files, distinguishes the differences with color marks, and improves the management of different versions of the same processing program file

5. NC filer and trace drawing function

extremednc system's NC program file compilation increases the steel consumption per square meter to 60 kg (the 2GB NC program file with the floor reinforcement editor is very useful for the machining program of complex parts. The trace drawing function is used to simulate and verify the tool path before the NC program file is sent to the machine tool.

6. powerful character conversion function

because some NC machine tools use keyboards with small character sets, and some characters in the file name of the NC file are not in the keyboard definition, it must be used The character conversion function converts some uncommon characters in the small character set keyboard into the characters you need. This function is often used in FANUC controllers

IV. the integration of DNC system and cad/cam/capp system

for system integration, we adopt the process shown in Figure 2. The NC program is generated by the cad/cam server according to the requirements of the CAPP server, and then transmitted to the CAPP server. After verification, the CAPP server is transmitted to the DNC server and allocated to the Outbox outbox of the corresponding NC processing equipment for call by the NC processing equipment

Figure 2 system flow chart

capp server is the key link of the whole process control, and its control interface is shown in Figure 3. After all items are filled in and confirmed, click the button to find the corresponding NC program, and then click the button to complete the transmission process of NC program from CAPP to DNC server, which is similar to the sending of e-mail

Figure 3 CAPP server control interface

v. conclusion

practice has proved the reliability, economy and progressiveness of the running model of the Integrated DNC technology based on NT local area in the NC workshop management system of Xuchang Tobacco machinery company. This technology has comprehensively improved the production efficiency of the NC workshop, and is an effective way to transform the theory of advanced manufacturing technology into the practical productivity of enterprises

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