Basic knowledge of CNC machining technology
The main content of numerical control programming includes: analyzing part drawings to determine the process, numerical calculations, writing machining programs, proofreading programs, and first piece trial cutting.
The specific steps of programming are described as follows:
1. Analyze the drawings and determine the manufacturing process
When machining parts on a CNC machine, the original data obtained by the process 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 cutting tool can be selected to determine the positioning clamping device, processing method, processing sequence, and cutting quantity. In determining the process of manufacturing, full consideration should be given to the command functions of the CNC machine tool used, and the efficiency of the machine tool should be fully utilized to achieve reasonable machining routes, fewer cutting times, and shorter machining hours. In addition, relevant process and technical documents should be filled in, such as CNC machining process cards, CNC tool cards, tool routing maps, etc.
2. Calculate the coordinate values of the tool path
Based on the geometric dimensions of the part drawing and the set programming coordinate system, calculate the motion trajectory of the tool and obtain all tool position data. General CNC systems have the functions of linear interpolation and arc interpolation. For contour machining of flat parts with relatively simple shapes (such as parts composed of lines and arcs), only the starting and ending points of geometric elements, the center of the arc (or the radius of the arc), and the coordinate values of the intersection or tangent points of two geometric elements need to be calculated. If the CNC system does not have tool compensation function, the coordinate values of the tool's motion trajectory need to be calculated. For parts with complex shapes (such as those composed of non-circular curves or surfaces), it is necessary to approximate the actual curve or surface with straight line segments (or arc segments) and calculate the coordinate values of their nodes based on the required machining accuracy.
3. Write part processing programs
Based on the machining route, the tool motion trajectory data and the determined process parameters and auxiliary actions are calculated. Programmers can write the machining program for the part 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: firstly, the standardization of program writing should be easy to express and communicate; 2、 On the basis of being fully familiar with the performance and instructions of the CNC machine tool used, the techniques for using each instruction and the skills for writing program segments.
