The NC machining process of the parts to be processed involves a wide range of issues. In this paper, combined with the possibility and convenience of programming, some main contents to be analyzed and reviewed are proposed.
1. Dimension marking should conform to the characteristics of NC machining
In NC programming, all the sizes and positions of points, lines and surfaces are based on the programming origin. Therefore, the coordinate size is directly given on the part drawing, or the dimension is quoted with the same datum as far as possible.
2. The conditions of geometric elements should be complete and accurate
In the process of programming, the programmer must fully master the geometric parameters of the part contour and the relationship between the geometric elements. Because it is necessary to define all geometric elements of the part contour in automatic programming, and to calculate the coordinates of each node in manual programming, no matter which point is unclear or uncertain, programming cannot be carried out. However, due to the part designer’s carelessness or neglect in the design process, the parameters are often incomplete or unclear, such as whether the arc and the straight line, the arc and the arc are tangent or intersecting or separated. Therefore, in the review and analysis of drawings, we must be careful, and timely contact the designer if problems are found.
3. The positioning datum is reliable
In NC machining, the working procedure is often concentrated, so it is very important to locate with the same datum. Therefore, it is often necessary to set some auxiliary datum or add some process boss on the blank.
4. Uniform geometry type or size
The shape and inner cavity of the parts are of uniform geometry type or size, which can reduce the number of tool change, and may also apply control program or special program to shorten the program length. The shape of the parts should be symmetrical as far as possible, so that it is convenient to use the mirror processing function of CNC machine tool to program, so as to save programming time.
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