What is the cause of tool collision failure in CNC machining center?

1. What is a tool collision?

Compared with ordinary machine tools, CNC machining centers have high machining accuracy, good dimensional stability, low labor intensity for workers, and are easy to modernize management. However, due to improper operation or programming errors, it is easy for the tool or tool holder to collide with the workpiece or machine tool. In the case of light damage, the tool and the processed parts will be damaged, and in the case of heavy damage, the machine tool components will be damaged, causing the machine tool to lose machining accuracy, and even causing personal accidents. Therefore, from the perspective of maintaining accuracy, the tool and the machine tool or workpiece must not be allowed to collide during the use of CNC machine tools. The following summarizes and analyzes the causes of tool collision.

2. What are the causes of tool collision?

Since the CNC machining center is locked by software, when the automatic operation button is pressed during simulation, it is not intuitive to see whether the machine tool is locked in the simulation interface. There is often no tool setting during simulation. If the machine tool is not locked and running, it is very easy to collide with the tool. Therefore, before simulation processing, you should go to the operation interface to confirm whether the machine tool is locked. Forget to turn off the dry run switch during processing. Because in the simulation of the program, the dry run switch is often turned on to save time. Dry run means that all the moving axes of the machine tool run at the speed of G00. If the dry run switch is not turned off during processing, the machine tool ignores the given feed speed and runs at the speed of G00, causing tool hitting and machine tool collision accidents. No return to the reference point after the dry run simulation. When the program is verified, the machine tool is locked and motionless, and the tool is in simulation operation relative to the workpiece/(absolute coordinates and relative coordinates are changing/). At this time, the coordinates do not match the actual position. The method of returning to the reference point must be used to ensure that the mechanical zero coordinates are consistent with the absolute and relative coordinates. If the processing operation is performed without finding any problems after the verification program, it will cause a tool collision. The direction of overtravel release is wrong.

When the machine tool is overtraveled, the overtravel release button should be pressed and moved in the opposite direction manually or by hand, which can be eliminated. However, if the release direction is reversed, it will cause damage to the machine tool. Because when the overtravel release is pressed, the overtravel protection of the machine tool will not work, and the travel switch of the overtravel protection is already at the end of the travel. At this time, the workbench may continue to move in the direction of overtravel, eventually breaking the lead screw and causing damage to the machine tool. The cursor position is improper when the specified line is running. When the specified line is running, it is often executed downward from the cursor position. For lathes, it is necessary to call the tool offset value of the tool used. If the tool is not called, the tool in the running program segment may not be the required tool, and it is very likely to cause a tool collision accident due to different tools. Of course, on machining centers and CNC milling machines, the coordinate system such as G54 and the length compensation value of the tool must be called first. Because the length compensation value of each tool is different, it may also cause a tool collision if it is not called.