CNC machine tool "limit alarm" cause analysis and processing - Database & Sql Blog Articles

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Due to the wide variety of machine tool numerical control systems, different equipment shapes and structures, various design methods, and various faults, it is quite difficult to maintain CNC equipment. While mastering the mechanical structure and electrical control principles, it must be reasonably analyzed, flexible, and good at summing up, in order to achieve twice the result with half the effort. Based on the principle, it is easy to difficult to narrow down the fault range and eliminate it. In order to ensure the safe operation of the machine tool, the linear axis of the machine tool is usually equipped with two protection "defense lines": soft limit (parameter setting limit) and hard limit (stroke switch limit). The limit problem is one of the common faults of CNC machine tools, and the related information is mentioned less. The following is the main reason for the "limit alarm" for some analysis and explanation.
1. The relevant control circuit is broken or the limit switch is damaged.

The reason for the "limit alarm" is relatively high. Because external components are greatly affected by the environment, such as mechanical collision, dust, corrosion, friction and other factors, it is easy to cause damage to the relevant limit switch itself and control circuit. Open circuit and generate "limit alarm" information at the same time. Also encountered when the overtravel switch is pressed and cannot be reset. The handling of such faults is relatively straightforward, and the damaged switches and wires can be repaired or replaced. Care should be taken to observe and observe the wire when the wire is broken or the contact is poor.

Such as: an XK755 CNC milling machine, using FANUC 0-M CNC system. During the machining process, the “X+, X-, Y+, Y-hard limit” alarm suddenly appears, but the machine tool is actually in the normal processing range. According to the above phenomenon, it is estimated that the line contact is poor or the possibility of disconnection is the greatest. The 24V voltage of the supply limit circuit on the terminal block of the electrical cabinet is measured, and the pressure value is normal. According to the route direction, one by one, when a line connector on the right side of the bed is rotated by hand, it is found that the alarm on the screen disappears instantaneously, and the alarm is reproduced in the hand. Therefore, the joint is removed, and it is found that the two wires welded inside have been detached, and the two ends of the wire break can be touched during the process of turning by hand, so the above change phenomenon occurs. After re-welding the joint, the machine returns to normal.