1. Analyze drawings and determine the process
When machining parts on CNC machine tools, the original data obtained by the follow-up personnel is the part drawing. According to the part drawing, the shape, dimensional accuracy, surface roughness, workpiece material, blank type and heat treatment condition of the part can be analyzed, and then the machine tool and tool can be selected to determine the positioning clamping device, processing method, processing sequence and cutting amount. In determining the process, the command function of the CNC machine tool used should be fully considered, and the efficiency of the machine tool should be fully utilized to achieve a reasonable processing route, a small number of tool passes and a short processing time. In addition, relevant process and technical documents should be filled in, such as CNC machining process cards, CNC tool cards, tool path maps, etc.
2. Calculate the coordinate value of the tool path
According to the geometric dimensions of the part drawing and the set programming coordinate system, the motion trajectory of the tool center is calculated to obtain all tool position data. Generally, CNC systems have the functions of linear interpolation and circular interpolation. For the contour processing of planar parts with relatively simple shapes (such as parts composed of straight lines and circular arcs), it is only necessary to calculate the coordinate values of the starting point, end point, center of the circular arc (or radius of the circular arc), and intersection or tangent point of the two geometric elements. If the CNC system does not have the tool compensation function, the coordinate values of the motion trajectory of the tool center must be calculated. For parts with complex shapes (such as parts composed of non-circular curves and surfaces), it is necessary to use straight line segments (or circular arc segments) to approximate the actual curve or surface, and calculate the coordinate values of its nodes according to the required processing accuracy.
3. Write part processing program
According to the processing route, the tool motion trajectory data and the determined process parameters and auxiliary actions are calculated. The programmer can write the part processing program segment by segment according to the functional instructions and program segment format specified by the CNC system used. When writing, attention should be paid to: First, the standardization of program writing should be easy to express and communicate; second, on the basis of being fully familiar with the performance and instructions of the CNC machine tool used, the skills of using each instruction and the skills of writing program segments.