The machining process of spiral bevel gears is relatively complex, and the tools used are special tools. The machining machine tools are diversified from special to general, and the machined tooth surfaces are spatial complex curved surfaces. These factors make it difficult to use general methods to carry out Boolean operations in cutting process. Therefore, the structure of the whole simulation system has certain particularity in a certain sense. According to the function investigation of general NC machining simulation software at home and abroad and the functional requirements of relevant users for spiral bevel gear forming simulation system, it is determined that the software functions in spiral bevel gear forming simulation system mainly include:
1) Parameter input and inspection function of cutter head and gear blank: according to different spiral bevel gear product design parameters, you can input the relevant basic shape parameters of cutter head and gear blank, draw the corresponding three-dimensional model of cutter head and gear blank according to their parameters, and prompt the user for wrong parameter input.
2) Machine tool adjustment parameter input function: through the human-computer interaction interface, you can also input machine tool adjustment parameters according to different processing methods to realize a variety of spiral bevel gear NC processing methods.
3) Automatic programming function of tooth surface forming NC Code: calculate according to the product design parameters entered by the user and the adjustment parameters of the machine tool, and automatically convert and generate the tooth surface forming NC program according to the specified NC system instruction code format and the motion mode of the cutter head and the tooth blank, so as to control the relative position and motion of the cutter, the tooth blank and the machine tool.
4) Simulation function of tooth surface forming process: it can establish a three-dimensional model including tooth blank, cutter head and CNC gear processing machine tool; Before the real gear processing, it can complete the simulation of the motion path of the cutter head, gear blank and the motion process of each part of the machine tool in the tooth surface forming process, so as to avoid the interference and collision in the actual cutting process.
5) CAD model data input function of machine tool parts: it can read the three-dimensional model data generated by the CAD modeling software in the specified format, display the model data to the user with graphic display technology, and store and manage the NC equipment model according to certain order and rules. According to different processing requirements and processing methods, CNC equipment can be selected between different machine tool series and within the same machine tool series, such as CNC gear milling machine, CNC gear grinding machine, CNC gear lapping machine and other CNC equipment with different functions.
6) Dynamic 3D graphic interactive display function: it can dynamically display the cutter, gear blank, gear and machine tool model in the machining process. In the process of machining simulation, through the control of NC program, the tool and gear blank move continuously. When the cutting process between the tool and gear blank occurs, the data points of the tooth surface can be updated and the gear blank can be reconstructed in real time. In the process of cutting simulation, the relative motion of machine tool components, cutting tools and gear blanks can also be controlled by NC program, so that their relative positions are consistent with those in actual machining. In addition, users can zoom, translate, rotate and other observation angle transformation operations on the display graphics at any time, in order to better observe the simulation processing process and simulation processing results.
7) Boolean operation function of fast spatial shape: including converting the adjustment parameters of traditional machine tools into numerical control programs, using MATLAB and VC mixed programming to calculate the intersection with tools after the slicing of gear blanks, Boolean operation of tools and gear blanks in the cutting process, etc.
8) Data output function: output the data points of the tooth surface obtained by simulation processing in a certain text format. Through reading and transformation, the gear model can be built in some 3D modeling software, and it can also be used in subsequent links such as TCA analysis; The NC program generated by converting the machine tool adjustment parameters is output in a certain text format, which can be used for the actual NC machining of spiral bevel gears; Outputting the gear solid model obtained by simulation processing in a certain file format can lay a foundation for the virtual rolling inspection of spiral bevel gear pairs. These simulation results make the simulation system have high scientific research value and use value.
According to the above functional requirements, the system structure of spiral bevel gear tooth surface forming simulation system is established by using the top-down hierarchical modeling method and the software module division principle of “strong cohesion and weak coupling”. The system is generally divided into main control layer, function module layer and data layer. Based on virtual reality technology, under the windows platform, VC is used as the programming tool, OpenGL is used as the standard graphics library, and MATLAB and VC mixed programming are used to realize the rapid solution of complex operations.
The highest level of spiral bevel gear tooth surface forming simulation system is the main control layer, which can decide to call the corresponding functional modules according to the process of tooth surface forming simulation, and is responsible for the data transmission between the functional modules.
The functional module layer of the tooth surface forming system includes eight functional modules: cutter head and tooth blank parameter input and inspection, machine tool adjustment parameter input, automatic programming of tooth surface forming NC code, tooth surface forming process simulation, CAD model data input of machine tool components, dynamic 3D graphic interactive display, fast spatial Boolean operation function and tooth surface forming data output. The function module is used to perform corresponding function operations according to the current instruction type and the required data type, and can access the data layer to store the processed data or call the relevant data information required by the current instruction operation.
The function of the data layer is to provide basic data storage and reading services for the function layer through data management tools. Among them, the program code of the tooth surface forming path of the specified machining method, the motion control command parameters of each machine tool part in the tooth surface forming process, the dynamic operation data of the NC spiral bevel gear machining machine tool under the typical tooth surface forming environment, the geometric parameters and motion parameters of each part of the machine tool, the parameters of different types of Cutterheads and blades, as well as the data of different parameter tooth blank and fixture models are stored in the form of database.
Using the above hierarchical architecture mode, each layer can provide services for the upper layer, and also call the functions or data of the lower layer. The module calls between different layers can be defined by determining the data interface protocol of inter layer interaction. By establishing and implementing the hierarchical function model of the tooth surface forming simulation system, the research of the system function modules can have a good reusable and expandable development space, including the expansion of NC machining functions of different spiral bevel gear tooth surface forming methods, the expansion of dynamic database management tools for various motion forms of digital control machine tool components, the expansion of various tooth surface forming data output formats, and so on.