50 cases of failure maintenance of the most popula

7.4 50 cases of failure maintenance of the spindle drive system

7.4.1 22 cases of failure maintenance of the FANUC spindle drive system 301. Severe shaking of the machine tool and al-04 alarm on the driver: a vertical machining center equipped with FANUC 6 system, during the machining process, severe shaking of the machine tool and al-04 alarm on the AC spindle driver. Analysis and treatment process: the meaning of FANUC AC spindle drive system al-04 alarm is "P1, F2, F3 fuses in the AC input circuit are blown", the possible causes of the fault are: 1) the output impedance of AC power supply is too high. 2) The inverter transistor module is poor. 3) The rectifier diode (or thyristor) module is poor. 4) The surge absorber or capacitor is poor. Check the causes of the above faults one by one. Check the AC input power supply. In the input power supply of the AC spindle driver, the input voltage of R and S phases is 220V, but the AC input voltage of T phase is only 120V, indicating that the three-phase input power supply of the driver has the problem of stable and reliable performance. Further check the three-phase output of the spindle transformer, and it is found that the input and output of the transformer and the power input of the machine tool are also unbalanced, which shows that the cause of the fault is not the machine tool itself. Check the three-phase fuse on the switch cabinet in the workshop, and find that one phase impedance is hundreds of ohms. It was found that the connecting screw of the fuse was loose, resulting in the imbalance of three-phase input power supply; After reconnection, the machine tool returns to normal. Example 302. The driver has the fault maintenance fault phenomenon of alarm "a": after starting up a CNC lathe equipped with FANUC 0t, the system is in the "emergency stop" state, displaying "notready", and the spindle alarm indicator on the operation panel is on. Analysis and treatment process: according to the fault phenomenon, check the AC spindle driver of the machine tool and find that the driver displays "a". According to the alarm display of the driver, it can be seen from the foregoing in this chapter that the meaning of the driver alarm is "driver software error". This alarm is easy to appear when the driver is accidentally disturbed by the outside. The solution is usually to initialize the driver. In this machine tool, the parameter initialization operation is carried out according to the following steps: 1) cut off the power supply of the driver and set the setting end S1 to test. 2) Power on the drive. 3) Press and hold mode, up, down and dataset at the same time. 4) when the display changes from full darkness to "fffff", release all keys and keep them for more than 1s. 5) Press and hold the mode and up keys at the same time to make the parameter display FC-22. 6) Press and hold the dataset key for more than 1s, the display shows "good", and the standard parameters are written. 7) Cut off the power supply of the driver and reset S1 (SH) to "drive". Through the above operations, the driver returns to normal, the alarm disappears, and the machine tool returns to normal operation. Example 303. Fault maintenance fault phenomenon of overcurrent alarm in the driver: a horizontal machining center equipped with FANUC 11m system suddenly stops the operation of the spindle during machining, and the driver displays overcurrent alarm. Analysis and treatment process: after checking the main circuit of AC spindle driver, it was found that the fuses of regenerative braking circuit and main circuit were all blown, and the machine tool returned to normal after replacement. However, the same fault occurred again after the normal operation of the machine tool for several days. Due to repeated failures, it is proved that there is a problem in the spindle system of the machine tool. According to the alarm phenomenon, the possible main reasons are analyzed as follows: 1) the main shaft driver control board such as beverage bottles is poor. 2) The motor is overloaded continuously. 3) There is a local short circuit in the motor winding after that. In the above points, according to the actual processing situation on site, the cause of motor overload can be eliminated. Considering that the driver can work normally for several days after replacing the components, the possibility of poor spindle driver control board is also small. Therefore, the most likely cause of the fault is the local short circuit in the motor winding. During maintenance, carefully measure the resistance of each phase of the motor winding. If u is relative to the ground, check whether there is water shortage in the water tank of the wet bulb sensor, and the insulation resistance is small, which proves that there is a local short circuit to ground in this phase. After disassembling the motor, it was found that the insulation sleeve at the connection between the internal winding of the motor and the outgoing line had been aged; After reconnection, the resistance to ground returns to normal. After replacing the components again, the machine tool returns to normal and the fault no longer occurs. Example 304. Maintenance fault phenomenon of main shaft driver Al-12 alarm: a horizontal machining center equipped with FANUC 11m system, during the machining process, the main shaft operation suddenly stops, and the driver displays No. 12 alarm. Analysis and treatment process: the meaning of No. 12 alarm of AC spindle driver is "DC bus overcurrent". From the foregoing in this chapter, the possible causes of the fault are as follows: 1) local short circuit at the motor output end or motor winding. 2) The inverter power transistor is poor. 3) The drive control board is faulty. According to the above reasons, careful inspection was carried out during maintenance. Confirm that there is no local short circuit at the motor output end and motor relay group. Then disconnect the power supply of the driver (machine tool) and check the inverter transistor assembly. Open the driver, remove the motor armature wire, and use a multimeter to check the resistance value between the collector (C1, C2) and emitter (E1, E2), base (B1, B2) of the inverter transistor assembly, and between the base (B1, B2) and emitter (EL, E2). Compared with the normal value (shown in the table), it is found that there is a short circuit between c1-e1, that is, the transistor assembly has been damaged. Table normal resistance value of inverter transistor assembly