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.
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1. Hard limit
In the positive and negative limit position of the servo axis, install a limit switch or close to the switch, which is the so-called hard limit. The hard limit is the ultimate protection for servo axis motion overtravel. It will reach 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 tight parking. 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 alarm, and the corresponding coordinate axis cannot 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 limitation defect.
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2. Soft limit The soft limit of the servo axis is based on the machine reference point as the basis of the machine parameter (1320, 1321 attributed to the axis parameter) to set the axis’s motion scale. If it exceeds this scale, it is said to have passed the soft limit. The software limit has no limit switch, but only a set of azimuth coordinate values.
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3. Limit exemption of CNC lathe 1. Soft limit exemption: Generally, just move the overtravel axis in the opposite direction of the overtravel to exit the overtravel area, press the reset button to cancel the alarm, and the machine recovers normally. 2. Hard limit exemption: Generally, it is necessary to press and hold the “overtravel release” (“overtravel exemption”) on the machine tool to move in the opposite direction. If the machine does not have a release button, try to move the screw in the opposite direction.
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