CNC programming refers to the whole working process from part drawing to obtaining CNC machining program.
1. Analyze part drawings and formulate process plans
The contents of this work include: analyzing the part drawings and clarifying the processing contents and requirements; Determine the processing scheme; Choose a suitable CNC machine tool; Select or design tools and fixtures; Determine a reasonable cutting route and select a reasonable cutting amount. This work requires programmers to be able to analyze the technical characteristics, geometry, size and process requirements of the part drawing, and determine the processing method and processing route in combination with the basic knowledge of the use of CNC machine tools, such as the specification and performance of CNC machine tools, the function of CNC system, etc.
2. Mathematical processing
After determining the process plan, it is necessary to calculate the tool center trajectory according to the geometric size of the part and the machining route, so as to obtain the tool position data. CNC systems generally have the functions of straight-line interpolation and arc interpolation. For machining simple plane parts composed of arcs and lines, only the coordinate values of the intersection or tangent point of adjacent geometric elements on the part contour need to be calculated, and the coordinate values of the starting point, end point and center of circle of each geometric element can be obtained, which can meet the programming requirements. When the geometric shape of the part is inconsistent with the interpolation function of the control system, it is necessary to carry out more complex numerical calculation. Generally, computer-aided calculation is required, otherwise it is difficult to complete.
3. Write part processing program
After the above process treatment and numerical calculation are completed, the part processing program can be written. The programmer uses the program instructions of the CNC system to compile the processing program paragraph by paragraph according to the specified program format. Programmers should be very familiar with the functions, program instructions and codes of CNC machine tools before they can write correct processing programs.
4. Procedure inspection
By inputting the programmed processing program into the CNC system, the processing work of the CNC machine tool can be controlled. Generally, the program should be inspected before formal processing. Generally, the machine tool can be idled to check the correctness of the machine tool action and motion trajectory, so as to test the program.
On CNC machine tools with graphic simulation display function, the program can be checked by displaying the tool path or simulating the cutting process of the tool on the workpiece. For parts with complex shape and high requirements, easy to cut materials such as aluminum parts, plastic or paraffin can also be used to test the procedure.
By checking the test piece, we can not only confirm whether the program is correct, but also know whether the machining accuracy meets the requirements. If you can use the same material as the processed parts for trial cutting, it can better reflect the actual processing effect. When you find that the processed parts do not meet the processing technical requirements, you can modify the program or take measures such as size compensation.
