There are 4 methods for machine tool maintenance: conventional inspection method, principle analysis method, isolation method, and exchange method:
1. Routine inspection method
The first method used in maintenance is to rely on the sense organs of the maintenance person and with the help of some ordinary instruments to find out the method of machine failure. In the event of a failure, first use methods such as watching, listening, smelling, and touching to check the following components one by one from the outside to the inside.
- 1) Check whether the thermal relay has tripped, whether the fuse, circuit board is damaged, and the oil level from the CRT.
- 2) Check the wiring and cables of the moving parts of the machine. The wiring of these parts is susceptible to fatigue and breakage.
- 3) Check wiring terminals, unit connectors and other components. These parts are prone to breakage or poor contact due to false welding, looseness, heat generation, oxidation or galvanic corrosion.
- 4) Check the components working in harsh environments. These components are susceptible to failure or aging due to heat, moisture, vibration, sticky dust or oil.
- 5) If the operator has moved the circuit board, he must also check the switch position, potentiometer setting, short-circuit selection, and whether the changed circuit is consistent with the original circuit, etc. And pay attention to whether the vibration, sound, smell, and operating temperature of the equipment are normal when the fault occurs. This check is simple, but very necessary.
2, principle analysis method
It analyzes the level and characteristic parameters (such as voltage value or waveform) of each contact according to the composition and working principle of the numerical control system, and uses a multimeter, oscilloscope or logic analyzer to measure, analyze and compare them, and then A method of system inspection for failures. To adopt this method, it is necessary to have a clear and in-depth understanding of each part of the circuit of the entire system.
When the “series” circuit fails, all components and connecting wires may be the source of the failure. For a long “series” circuit, you can start from the middle to track in both directions until you find the faulty unit.
3, isolation method
It is a method of narrowing the fault area by disconnecting the control circuit. In order to prevent the expansion of the fault during machine maintenance, it is necessary to cut off the power of certain components, and this method is often used. The feedback of cnc machine tools is complicated, and the consequences must be considered when cutting off certain control circuits. It is forbidden to disconnect the protection circuit.
4. Exchange method
For two identical lines, a partial exchange test can be performed on them. But for CNC machine tools, the problem is not so simple. To exchange a unit, it is necessary to ensure the integrity of the major link (ie the position control loop) where the unit is located. Otherwise, the closed loop may be destroyed, the protection link will fail, and the input of the integral regulator will not be balanced.