The main contents of NC programming are: analyzing the part pattern to determine the process, numerical calculation, writing the machining program, proofreading program and the first piece of trial cutting.

 

 

The specific steps of programming are as follows:

 

 

1. Analyze the pattern and determine the process

 

 

The parts processed by the craftsman are the part drawings. 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, the tool, the positioning clamping device, the processing method, the processing sequence and the cutting amount can be determined. size. In the process of 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 passes and a short processing time. In addition, you should also fill in relevant technical documents, such as CNC machining process cards, CNC tool cards, and route maps.

 

 

2. Calculate the coordinate value of the tool path

 

 

According to the geometrical dimensions of the part drawing and the programmed coordinate system, the tool's motion trajectory is calculated and all the tool position data is obtained. Generally, the numerical control system has the functions of linear interpolation and circular interpolation. For contour processing of flat shapes with simple shapes (such as parts composed of straight lines and circular arcs), only the starting point, end point and arc of the geometric elements need to be calculated. The center of the circle (or the radius of the arc), the intersection of the two geometric elements, or the coordinate value of the tangent point. If the CNC system has no tool compensation function, calculate the coordinate value of the tool's motion path. For parts with complex shapes (such as parts consisting of non-circular curves and curved surfaces), straight lines (or arc segments) are required to approximate the actual curve or surface, and the coordinates of the nodes are calculated according to the required machining accuracy.

 

 

3. Write a part program

 

 

According to the machining route, the tool movement trajectory data and the determined process parameters and auxiliary actions are calculated. The programmer can program the parts according to the function instructions and the program segment format specified by the numerical control system. At the time of writing, it should be noted that: First, the normative nature of the program should be easy to express and communicate; Second, on the basis of the full familiarity with the performance and instructions of the CNC machine tools used, the techniques used in each instruction and the skills of the program segment preparation.