What is the self diagnosis function of CNC machine tools

m instruction (or accessibility function).

The auxiliary function is represented by the address word M and two digits, and it is mainly used for process instructions during machine tool machining operations. It is characterized by relying on the relay on and off to achieve its control process. The table below shows Fanuc

M-Command Function Table of O-T CNC System.

The M00 program is paused.

After the execution of M00, all the actions of the machine tool are cut off, and the program start button is pressed again, and then the following program segment is continued. *The optional pause execution process for M01 is the same as for M00, except for the "Optional" on the machine control panel.

The command is only valid when the "Stop" switch is placed in the ON position. The main program of M02 ends by cutting off all movements of the machine tool and resetting the program. The M03 spindle rotates forward and the M04 spindle reverses.

M05 Main. Axis M06 turret indexing The tool change command (M06) must be combined with the tool selection command (T command) in order to complete the tool change action correctly. M07 cutting fluid on * M09 cutting fluid off * M98 calls the subroutine and then the P address specifies the subprogram number, and the L address transfers the number of times.

The m99 subroutine ends, and the subroutine ends, and returns to the main program.

For the fault of the electrical system of the CNC lathe, the process of investigation, analysis and diagnosis of the fault, that is, the process of troubleshooting, so the method of fault diagnosis is particularly important. Here is a brief description of some commonly used diagnostic methods.

1. Intuitive method. It mainly adopts visual inspection, hand touching, power-on and other methods.

The first method used by maintenance personnel in fault diagnosis is the visual inspection method.

First of all, it is necessary to consult the on-site personnel who have failed in detail about the process, failure phenomenon and consequences of the failure, and to inquire many times in the whole analysis and judgment process;

The second is to carefully inspect and gradually investigate from the outside to the inside according to the principle of fault diagnosis. Check whether the electronic control devices of the machine tool (such as lubrication devices, numerical control systems, temperature control devices, etc.) have alarm indications, whether the working state of each part is in a normal state (such as the position of the manipulator, the state of the spindle, the position of each coordinate axis, the tool magazine, etc.), the machine tool should observe whether there is a short circuit or open circuit on the circuit board, whether the circuit board components and circuits have cracks, burns and other phenomena, whether the chip is in poor contact and other phenomena, and whether the repaired circuit board should be checked for missing parts, wrong parts and broken wires;

The third is touch, under the condition of power-off of the whole machine, you can find the possible cause of the fault by touching the installation status of each main circuit board, the plug seat of the plug base, the connection status of each power and signal wire (such as the connection between the servo and the motor contactor).

2. Self-diagnosis function method. The self-diagnosis function of the numerical control system is used to give alarm information and indicate the approximate cause of the failure.

3. Exchange method. Swap identical modules and units with each other and observe failovers to quickly identify the location of the fault.

4. Instrumental measurement comparison method. When the system fails, the conventional electrician testing instrument is used to measure the voltage, power supply, pulse signal, etc. of the fault part, and compare the normal value with the value at the time of the fault, and the cause and location of the fault can be analyzed.

The instrument inspection method uses conventional electrical instruments to measure the relevant DC and pulse signals and the voltage of each group of AC and DC power supplies, so as to find out possible fault problems. For example, take a multimeter to check the power supply, and measure the relevant signal status monitoring points arranged on some circuit boards, take an oscilloscope to observe the amplitude, phase or presence or absence of the pulsating signal, and use a PLC programmer to detect the fault points and causes in the PLC program.

5. Percussion method. The numerical control system is composed of a variety of circuit boards, each circuit board has a lot of solder joints, any virtual soldering or poor contact may appear to fail, you can use the insulator to gently knock on the suspicious point with virtual soldering or poor contact, if the fault appears, the fault is likely to be in the knocking part.

The above methods are used at the same time to carry out comprehensive fault analysis, which can quickly diagnose the fault location, so as to quickly eliminate the fault.

(1) Power on self-test.

When the CNC system is powered on, the internal self-diagnosis software of the system detects the key hardware and control software in the system one by one, once the detection fails, the alarm information is not displayed on the CRT, pointing out the fault location, only the boot self-test items are all normally passed, and the system can enter the state of normal operation preparation. The boot self-test can generally locate the fault on the circuit or module, and some can even locate it on the chip, but in many cases, the fault cause can only be located within a certain range, and the fault cause can be found and eliminated only through further inspection and judgment.

2) Real-time self-diagnosis.

When the CNC system is running, it automatically tests and checks the inside of the system, the servo system, the IO interface and other external devices of the CNC device at any time, and displays the relevant status information. If there is a problem in the detection, the alarm number and alarm content will be displayed immediately, and it will automatically decide whether to stop the operation or stop the machine according to the nature of the fault. During the inspection, the maintenance personnel can further diagnose and eliminate the fault according to the alarm content, combined with the real-time display of the NC internal key sign register and the operation unit status of the PLC.

After troubleshooting, the alarm is often not automatically eliminated, according to different alarms, you need to press"reset"or"stor"Soft key to restart, or if a power reset or shutdown is required to restart, the system is restored.

To sum it up, it is just four words: ask, look, listen, and touch.

Q: Ask the operator about the operating status of the circuit and equipment before and after the fault and the symptoms after the failure, whether the fault occurs frequently or occasionally; Whether there are any signs of noise, smoke, sparks, abnormal vibrations, etc.; Whether there is excessive cutting force and frequent starting, stopping, braking, etc. before the failure occurs; Whether it has been maintained, overhauled or changed the line, etc. Look:

Check whether there are obvious visual signs, such as various signals, before the fault occurs; In the case of a fuse with an indication device; Tripping action to protect electrical appliances; Wiring falls off; contact singeing or fusion welding; The coil is overheated and burned, etc. Listen: On the premise that the road can still run and the equipment is not damaged, you can power on the test and listen carefully to whether the sound of electrical appliances such as motor contactors and relays is normal.

Touch: After cutting off the power supply, touch and check the motor, transformer, electromagnetic coil and fuse as soon as possible to see if there is overheating.