CAPP for machining of the hottest rod parts

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Abstract: This paper introduces a CAPP method for connecting rod parts based on AutoCAD software, which has the advantages of short design cycle, low labor intensity and high quality

key words: connecting rod; CAPP

connecting rod is a typical rod part, which is generally processed by professional manufacturers or special production lines through thirty or forty processes according to strict process documents. If the process and document design are carried out manually, the labor intensity is high, the design cycle is long, and the quality is not easy to guarantee. But using computer aided process planning (CAPP) can overcome the above defects. Due to the different size head holes and center distance of connecting rods with the same structure, the machining process requirements are mainly reflected in the changes of dimensions and tolerances, which provides better process conditions for the realization of CAPP. In addition, with the emergence of ads, autocadsql and its extended ASE and other development interfaces in autocad12.0 and above versions, it provides good technical conditions for the rapid realization of CAPP with higher quality

1.1 principle and composition of the system

1.1 working principle

the system completely simulates the manual design of connecting rods by engineers and technicians. The tensile function of the experimental machine is still applicable to the method of technological process in the anti-corrosion coating of steel pipelines. In the process of automatic or interactive design of the process card of a certain process, the design of all related process documents is completed. The process is shown in Figure 1

1.2 overall structure

the system is composed of database, program library and graphics library, and the data between each library can be dynamically connected, as shown in Figure 2

2 processing of connecting rod process data

2.1 determination of standard process procedures

the processing technology of connecting rod has a strong regularity. If connecting rods with the same structure are classified into a family according to the model, their processing process route is the same, but the process data and process size are different. Therefore, when the user enters the model of crankshaft, the system can call the corresponding three databases of process route, tools and equipment in the database according to this parameter, and call the corresponding original process diagram card from the graphics library. The system also establishes a comprehensive process database that comprehensively records the process data of the workshop, so that users of advanced medical equipment can browse, supplement and modify in the process card design

2.2 determination of process dimension

refer to the slide of connecting rod, enter the dimension and tolerance in the dialog box in turn, and then the final part dimension can be obtained systematically. According to the principle of reverse programming, the machining dimensions and tolerances of each process are calculated by calling the corresponding allowances and tolerances in the process dimension database, and marked on the corresponding position of the process map. The data in the process conversion dimension library can be determined by the on-site technologist according to the type and size of the connecting rod. At the same time, the data can be easily modified or added through the database management subsystem

3 dynamic connection of process data

3.1 establishment of standard process card

establish a standard process card graphic library according to the shape of the connecting rod in Auto CAD. Each type of standard process is a drawing file, and the card of each process occupies a drawing layer with the process number as the serial number, and the process drawing is not dimensioned. After the process data is dynamically connected to the external database through ASE, it is filled in the process card. First, initialize ASE, specify the corresponding standard tool and equipment databases respectively, search the data of tools, measuring tools and equipment according to the process number, connect the external data with horizontal grid as an entity at the corresponding position of the card, and write it out by the data loading command. In this way, the process data of all layers are written out, and the process card and the dynamic connection with the external database are saved in the form of graph when saving and exiting

3.2 modification of process card

some modifications are likely to be made in the process of connecting rod process specification design. To modify the process data, you can use the ASE command, pick up the data to be modified with the mouse, open the external database, and then reload the data after modification, so that the database and the operation card will be similarly modified. If you want to select data that is not in the standard library, you can enter the data browsing module through the menu or command, search for appropriate tools in the comprehensive process database of hr15t hardness test in the workshop, and the boundaries of different colors should be clear. Through the addition and deletion of standard tools and equipment databases, data loading, complete the change of process data. The operation commands of Auto CAD can be directly used to modify the process drawing, and the modification of process dimension and tolerance can also be obtained by changing the data of process connection dimension library and re running the program

4 conclusion

by using the ASE database interface technology of AutoCAD and ads programming technology, we can realize the dynamic connection of various data in the design of connecting rod process specification. Through the combination of automation and interaction, we can simulate the design process and method of artificial connecting rod process specification. The system not only greatly shortens the design cycle, reduces the labor intensity, but also improves the quality of process documents. The further development direction of the system is to use the SQL database interface technology in AutoCAD to replace the general ASE command and combine the design characteristics of crankshaft process specification. Further improve the adaptability and automation of the system. (end)

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