When machining the side of a part on a CNC milling tool, the tool has a radius. To machine this side, the center path of the tool is offset along the workpiece by a radius. This radius offset is the tool radius correction. The shape of a part consisting of a straight line, an arc, etc., in the actual processing, if the tool radius is too large, it will often cause over-cutting. Excessive cutting of the tool is called "interference", and the pre-interference check can check whether the tool is over-cutting, which can avoid unnecessary troubles in processing, thereby improving the processing efficiency and reducing waste.
The introduction of 1 vector To facilitate the discussion of interference checking, first make a vector at the key points of the part, then make a tool center path and mark the direction. The center path of the tool can be compared with the program path direction, and whether or not to interfere can be judged from the difference between the two. Here, only the linear-linear, linear-arc part of the contour processing of the interference problem. Among them, V1, V2, V3, and V4 are the vectors of the center path of the tool at the two arc connecting points A and B, that is, the key points.
2 Interference judgment conditions Interference judgment conditions: The path of the tool is different from the path of the program (90° or more and 270° or less). When the tool is machining the shape of the part, the path is opposite to the machining direction and interference occurs.
3 Interference pretreatment When tool path compensation is performed on blocks A, B, and C of the program, multiple vectors (V1, V2, V3, V4) are generated between A and B, and multiple vectors are generated between B and C (V5, V6, V7). , V8). First of all, it checks whether or not to interfere with the two most recent vectors. If it interferes, it performs interference processing, and then intervenes in the nearest two or two vectors.
If during the inspection, the two vectors examined are all interfered, the CNC will automatically cancel the interference and the tool will move linearly.
Interference checking and interference processing are as follows:
Between V4 and V5 - Interference - Eliminate between V3 and V6 - Interference - Elimination
Between V2 and V7 - Interference - Eliminate between V1 and V8 - Interference - Elimination
After removing all the interference, the tool moves linearly from V1-V8.
If during the inspection only one of the single blocks of the vector interferes, the CNC automatically cancels the interference and the linear movement of the tool occurs.
Interference checking and interference processing are as follows:
Between V4 and V5 - Interference - Elimination between V3 and V6 - Interference - Elimination
Between V2 and V7 - Do not interfere between V1 and V8 - Interference - Elimination
After removing all the interference, the tool movement is: V1-V2-V7-V8.
4 false interference In the program, there is actually no interference, but because the direction of the single-block B program is the opposite of the tool path correction, the tool will stop.
(1) The recess is smaller than the tool radius compensation amount.
There is actually no interference, but because the block is in the opposite direction of the path of the tool path in the direction of the single block B program, the tool stops here and an alert is displayed.
(2) Grooves smaller than the tool radius compensation amount.
In the opposite direction of the tool path correction direction in the direction of single block B program, the tool stops and an alarm is displayed.
5 Summary Some complicated part shapes are actually composed of some simple straight-line and straight-arc shapes. Through the interference discussion, numerical control programmers can perform interference analysis on some key points to judge whether they interfere. It has a certain significance for practice.
