CNC machining process analysis involves a wide range of applications, and only analyzes the possibility and convenience of CNC machining.
(一) The size data on the part drawing should be given in accordance with the principle of convenient programming.
1. The dimensioning method on the part drawing should be adapted to the characteristics of CNC machining. On the CNC machining part drawing, the size should be quoted with the same reference or the coordinate size should be directly given. This method of labeling is both easy to program and easy to coordinate between dimensions, and it is very convenient to maintain the consistency of design basis, process reference, test reference and programming origin setting. Since the part designer generally considers the use characteristics such as assembly more in the dimensioning, and has to adopt the partially dispersed labeling method, this will bring a lot of inconvenience to the process arrangement and the numerical control processing. Since the numerical control machining precision and the repetitive positioning accuracy are high, the use characteristics are not destroyed due to a large accumulation error, so the local dispersion notation method can be changed to the same reference engraving size or the coordinate method directly giving the coordinate size. .
2. The conditions for the geometric elements that make up the contour of the part should be sufficient
The base point or node coordinates are calculated during manual programming. When programming automatically, all geometric elements that make up the part's outline are defined. Therefore, when analyzing the part drawing, it is necessary to analyze whether the given conditions of the geometric element are sufficient. For example, an arc and a straight line, the arc and the arc are tangent to the pattern, but according to the dimensions given in the figure, when the tangency condition is calculated, it becomes an intersecting or dissociating state. Due to insufficient conditions for the geometric elements of the part, it is impossible to start programming. In this case, it should be resolved in consultation with the part designer.
(二) The structural processability of each part of the part should conform to the characteristics of CNC machining
1. The internal cavity and shape of the part are preferably of uniform geometry and size. This can reduce the tool size and the number of tool changes, making programming easier and improving production efficiency.
2, the size of the inner groove rounding determines the size of the tool diameter, so the inner groove fillet radius should not be too small. The quality of the part is related to the height of the contour to be machined and the radius of the adapter arc.
3. When the part is milling the bottom plane, the radius r of the groove bottom should not be too large.
4. A uniform benchmarking should be used. In CNC machining, if there is no uniform reference positioning, the contour position and size of the two faces after machining will be uncoordinated due to the re-installation of the workpiece. Therefore, to avoid the above problems, to ensure the accuracy of the relative position of the two clamping processes, a uniform reference positioning should be adopted.
It is better to have a suitable hole as the positioning reference hole on the part. If not, set the process hole as the positioning reference hole (such as adding a process lug on the blank or setting the process hole on the margin to be milled in the subsequent process). If it is not possible to make a process hole, at the very least, the finished surface should be used as a uniform reference to reduce the error caused by the two clamping.
In addition, it should also analyze whether the machining accuracy, dimensional tolerances, etc. required by the parts can be guaranteed, whether there are any unnecessary dimensions that cause conflicts, or the closed size that affects the process arrangement. |
