Virtual CNC Milling Process (1) Virtual CNC Milling Workflow A complete virtual CNC milling system should start with the CAD model of the workpiece, considering that the process of generating NC files from CAD models is already in many existing CAD/CAM software. It can be realized, so the system uses NC file as input, through the lexical, grammar check and compilation process of NC file, realizes the simulation and parameter feedback of CNC milling processing, and then judges the rationality of the design. The workflow is as shown.

To realize the dynamic simulation of the machining process, the main problem is to control the real-time display of the workpiece shape and the motion of the workbench according to the requirements. The motion of the worktable is realized by the position interpolation node of the VRML contact sensor. The shape of the workpiece changes continuously as the table moves relative to the tool. When the contact sensor node receives the input, the corresponding output is transmitted to the time sensor node, and the time sensor node transmits the output to the position interpolation node, and also outputs the output to the callback function in the Java program, and the workpiece shape is calculated in the function. And return the calculation result to the solid modeling node, so that the shape of the workpiece changes.

Similarly, the application of VRML nodes and Java data exchange, using the corresponding algorithms, can achieve functions such as milling force simulation, surface topography simulation.

(II) Cycloidal wheel virtual machining example The virtual CNC milling process is completed under the control of the main control interface. The function modules of the main control interface include parameter input and blank generation module, NC file reading module, and machining coordinates real-time. Display module and surface topography and milling force simulation module. The following is an example of the virtual processing of the cycloidal wheel.

1. Parameter input and blank generation module This module prompts the relevant size parameters to be input according to the blank shape selected by the user, and selects the milling cutter parameters and workpiece materials according to the processing needs. Finally, click the “OK” button to work on the table in the VRML scene. The blank is generated at the corresponding position.

2, NC file reading module CNC machine tool is based on the NC file to process the part, in this virtual CNC milling machine, also need a program input and machine tool according to the NC file processing parts. In the processing example of the cycloidal wheel, the program read in is the saved NC file. After the NC file is uploaded to the server, enter the file name in the "NC file" column, and click "Read" to read. The output file is displayed in the text box of the control interface. When compiling the code, the program in this text box is also decoded. Alternatively, the user can enter the NC code directly in the "NC Code" column. With the first method, the NC file can be reserved on the server side, and the file name can be entered when the next login, and the second method can be used. After the current page is closed, the NC code is not retained.

3. Machining coordinate real-time display module This module is used to display the coordinates of the tool relative to the workpiece machining origin. The operator can judge whether the tool or table feed amount meets the requirements according to the displayed coordinates, and can also reflect the current processing progress.

4, surface topography and milling force simulation module The main function of this module is to visually display the surface topography and milling force curve, and get the maximum and minimum. After processing, click the “Surface Topography” button to display the surface topography in the VRML interface on the left side. Click the “Milling Force” button to pop up the milling force curve and the maximum value for the user to analyze.

Conclusion This paper closely combines the needs of advanced manufacturing technology, takes virtual manufacturing technology as the research object, theoretically analyzes the processing process of virtual CNC milling system based on VRML, studies the principle and implementation scheme of NC file correctness test and the dynamics of machining process. Key technologies such as simulation, processing state parameter extraction, milling force, and surface topography simulation. On this basis, by compiling the NC file, the machining data is extracted, and finally the motion control of the virtual milling machine table and the real-time display of the workpiece shape are realized. Finally, taking the cycloidal tooth profile processing as an example, the system is verified by an example. The results show that the system can basically achieve the predetermined functions and achieve the intended purpose.

(Finish)

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