Application Research of CAPP in Free Forging

CAPP (Computer Aided Process Planning) is an important branch of computer-aided technology and a bridge between CAD and CAM. Free forging is a method of metal plastic working. It uses the upper and lower anvils of the forging equipment and some simple general tools to make the blank plastically deform under pressure. This paper has developed a set of free forging CAPP intelligent system, which is specially used for the automatic generation of free forging process procedures with good results.

Functional analysis of 1 free forging CAPP intelligent system

Combined with the actual analysis of free forging, the free forging CAPP intelligent system should have three major functions: the process design function of the forging, the output function of the process card and the management function of the process card.

The process design function of the forging is the core of the system. The work that needs to be done mainly includes: determining the weight and size of the blank, the margin and tolerance of each processing dimension, the forging temperature condition and the heat treatment specification of the forging, and formulating the deformation process and selecting the forging equipment. , put forward technical requirements for forgings, etc.

The output function of the process card is the final evaluation basis for the system's pros and cons. The final result of the system process design should be input in the form of a process card. Therefore, the drawing format of the process card should conform to the national standards and manufacturers' habits. The graphics require clear lines, reasonable font requirements, and overall aesthetics.

The management function of the craft card is also an indispensable part. The management of the process card includes the modification, saving, invoking and querying of the process card that has been generated.

2Structural analysis of CAPP intelligent system for free forging

According to the functions that the system needs to achieve, its structural framework can be determined (not shown).

The free forging user interface is the operating platform that the user directly faces. The interface window layout should be reasonable and beautiful, the display information should be clear and comprehensive, and the interface is friendly.

The free forging database is the basis for the implementation of system functions. The database stores various resource information and data required for system operation, such as margin tolerance information, heat treatment information, profile inventory information, and process card template information.

The part information input module is used for basic information of human-machine interactive input parts. The basic information of the part includes the basic information of forging and CAD parameter information, which is the basis and reasoning basis of the process design.

The intelligent process design module is the main body of the system. Its function is based on the part information, and the machining process route and parameters of the parts are calculated according to the established reasoning logic.

The process card management module is used to output, modify, store and query the final process rules generated by the system according to the standard format of the enterprise process file.

The database management module is used to organize and manage the knowledge data in the process knowledge base, so that the knowledge can be expanded and maintained, and the accidental loss and destruction of data can be prevented.

3 key technologies for free forging CAPP intelligent system

(1) Application of group technology

Free forging is a highly versatile process that is forged in a wide variety of shapes and shapes. In order to facilitate the production and preparation of process specifications, it is necessary to use group technology to classify forgings.

According to the structural characteristics of the actual forgings, the system divides the forgings into the following categories: flanges, seats, straight shafts, crankshafts, disc sleeves, blocks, hooks and so on.

After the forgings are classified, the same parameter expressions can be used for the same type of forgings when the system software is implemented, so as to realize the parameterized input of the CAD information of the parts. In the system, the corresponding code is set for each forging category, and the system calls the corresponding module code through this code to realize the preparation of the process specification of the forging.

(2) Application of expert system technology

The establishment of free forging CAPP intelligent system is inseparable from expert system technology.

The expert system usually consists of four main parts: the knowledge base, the inference engine, the knowledge acquisition part and the interpretation interface. The knowledge base and the inference engine are the core parts of the expert system.

The knowledge base of the free forging CAPP intelligent system is to express the process information and process expert experience in the forging process manual and various standards in the form of a database, which can be called at any time by the inference engine.

The inference engine of the free forging CAPP intelligent system is the mechanism for controlling and coordinating the work of the entire expert system. It extracts the basic data from the knowledge base and processes the raw data according to the specific inference strategy and order to obtain the final process data. .

(3) Application of database technology

As far as the system is concerned, the main problems to be solved by database technology include how to obtain data knowledge from the database, how to modify the knowledge of obtaining data, how to back up and restore data records, and how to summarize the data information.

According to the actual situation of free forging, the database system is divided into three independent subsystems, namely: process template database system, special system database system and process file database system. The process template database is used to store the process card template information, the expert system database stores various process parameters, judgment conditions and other information, and the process database is used to store process file information.

4 system implementation

4.1 User Interface Design

The user interface of the forged CAPP expert system consists of two parts: (1) user menu; (2) blank craft card. The menu consists of five items: process card, modification, data management, viewing view, and help. The process card menu includes basic operation items such as new, open, save, and print; the modification menu mainly includes modification of general parameters, technical requirements, heating specifications, margin tolerances, and forging equipment; data management is to back up data. Viewing view settings are browsing operations such as zooming in and out of the view; the help contains help files for system operations.

The blank craft card is set according to the manufacturer's craft card template. The user interface diagram of the forged CAPP expert system is omitted.

4.2 Design of the dialog window

According to the process of process design, the system design has a general parameter input frame, an additional information input frame, a technical requirement input frame, and a part size input frame. The general parameter input box is used for basic information such as part name, product name, code number, etc., and the additional information input box is used to input basic information about forging; the technical requirement is used to input some special forgings. Heat treatment requirements; part size input box is used for the geometric size information of the input part. Figure 1 shows the general parameter input box and the additional information input box window.

4.3 system application examples

Figure 2 is a process card for a stepped shaft generated using the system.

5 Conclusion

Forging is an important machining method, and most forging is free forging. The free forging process rules play an important guiding role in the processing. The use of CAPP technology intelligent automatic generation of forging process procedures can greatly shorten the preparation time of process procedures, improve design efficiency, and greatly promote the standardization, informationization and automation of enterprises.