In order to ensure the safe operation of the CNC lathe, both ends of each linear axis are limited. The limit of CNC lathe can be divided into soft limit, hard limit and mechanical hard limit.
1. Hard limit
In the positive and negative limit positions of the servo axis, a limit switch or proximity switch is installed, which is the so-called hard limit. The hard limit is the last protection against the overtravel of the servo axis. It reaches the mechanical hard limit within a short distance after crossing the hard limit. Due to the high power of the servo system, once it hits the mechanical hard limit, it may cause damage to the mechanical parts, which is not allowed. Therefore, the result of the hard limit switch action is to cause an emergency stop. When the feed axis moves beyond the stroke of the machine tool, the limit of the machine tool will take effect, and the machine will give an alarm, causing the corresponding coordinate axis to not continue to move during manual or handwheel operation; all coordinate axes will stop processing during automatic processing. At this time, we believe that the CNC lathe has a limit fault.
2. Soft limit The soft limit of the servo axis is based on the reference point of the machine tool and set with the machine parameters (1320 and 1321 are axis-type parameters) of the axis’s motion range. If it exceeds this range, it is said to have passed the soft limit. The software limit has no limit switch, but only a set of position coordinate values.
3. Releasing the limit of the CNC lathe 1. Releasing the soft limit: Generally, you only need to move the overtravel axis in the opposite direction of the overtravel to exit the overtravel area, press the reset button to clear the alarm, and the machine tool returns to normal. 2. Hard limit release: Generally, it is necessary to move in the opposite direction while pressing “Overtravel Release” (“Overtravel Release”) on the machine tool. If the machine does not have a release button, try to move the lead screw in the reverse direction.
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