Fault self-diagnosis methods and uses of CNC machine tools

1. Power-on self-diagnosis: The so-called power-on self-diagnosis refers to the diagnosis automatically performed by the system’s internal diagnostic program when the control system is powered on. It is similar to the computer’s power-on diagnosis. Power-on self-diagnosis can automatically check the key hardware in the system, such as: CPU, memory, I/O unit, CRT/MDI unit, paper tape reader, floppy drive and other devices; determine the installation, connection status and performance of the specified equipment: Some systems can also diagnose certain important chips, such as PAM, ROM, dedicated LSI, etc. The self-diagnosis of the CNC system is performed when it is turned on. Only when all items are confirmed to be correct can it enter the normal operating state. The diagnostic time of a cnc brass parts generally only takes a few seconds, but some may take several minutes. Power-on self-diagnosis is generally carried out according to the prescribed steps. Taking the FANUC II system of FANUC Company as an example, during the execution of the diagnostic program, the seven-segment display on the system motherboard presses 9→8→7→6→5→4→3→2→ The sequence of 1 changes, and the corresponding inspection content is: 9-Reset the CPU and start executing diagnostic instructions: 8-Perform ROM test, indicating that the ROM check error occurs, the display changes to b; 7-Clear the RAM, and the system resets the RAM Clear the contents in and prepare for normal operation; 6. Initialize a pair of BAC (bus random control) chips. At this time, if the display changes to A, it means there is an error in the transmission between the motherboard and the CRT; if it changes to C, it means a connection error; if it changes to F, it means the I/O board or the connecting cable is defective; if it changes to H, it means the used The connection unit identification number is incorrect; a lowercase letter c indicates an optical cable transmission error; a J indicates a defective PLC or interface conversion circuit, etc. 5 – Check the MDI unit 4 – Initialize the CRT unit 3 – Display the initial screen of the CRT, such as software version number, serial number, etc. At this time, if the display changes to L, it indicates that there is a problem with the PLC control software; if it changes to O, it means that the system failed to pass initialization and there is a problem with the control software: 2-Indicates that the initialization of the system has been completed; 1-Indicates that the system is functioning normally If the display changes to E during operation, it means that the system’s main board or ROM board, or the CNC control software is faulty. Under normal circumstances, after the CRT initialization is completed, if there is a fault in other parts, the CRT can display an alarm message.

2. Online monitoring Online monitoring can be divided into two forms: CNC machining agitator parts internal program monitoring and monitoring through external equipment. CNC internal program monitoring is a method of automatically diagnosing, checking and monitoring the status of each part through the system’s internal program. The scope of online monitoring includes the CNC itself and the servo units, servo motors, spindle servo units, spindle motors, external equipment, etc. connected to the CNC. Online monitoring is always effective during system operation. The internal program monitoring of the CNC system includes three aspects: interface signal display, internal status display and fault display.

⑴ Interface signal display It can display the current status of all interface signals between CNC and PLC, CNC and machine tool. Refers to the on-off status of digital input/output signals to help analyze faults. During maintenance, it is necessary to understand the meaning of each signal between CNC and PLC, CNC and machine tool, as well as the various conditions for signal generation and cancellation in order to carry out corresponding inspections. The “Function Manual” and “Connection Manual” provided by the CNC system manufacturer and the “Machine Tool Electrical Schematic Diagram” provided by the machine tool manufacturer are technical guides for the above status inspection. ⑵ Internal status display generally uses the internal status display function. The following aspects can be displayed:

1) External reasons that cause the cycle instruction (processing program) to not be executed. For example: whether the CNC system is in the “in-position check” state: whether it is in the “machine tool lock” state: whether it is in the “waiting for speed arrival” signal: whether it is waiting for the measurement signal of the “position encoder” when programming each spindle revolution. ; During thread cutting, whether it is waiting for the “spindle I rotation signal”, whether the feed speed override is set to 0%, etc.

2) Reset status display, indicating whether the system is in the “emergency stop” state or the “external reset” signal is on. 3) TH alarm status display. It can display the position of the paper tape error hole when alarming. 4) Display of memory contents and abnormal status of bubble memory.

5) Display of position following error.

6) Control information display of servo actuator part

7) Input pulse display of position measuring components such as encoders and gratings, etc.
1. Power-on self-diagnosis: The so-called power-on self-diagnosis refers to the diagnosis automatically performed by the system’s internal diagnostic program when the control system is powered on. It is similar to the computer’s power-on diagnosis. Power-on self-diagnosis can automatically check the key hardware in the system, such as: CPU, memory, I/O unit, CRT/MDI unit, paper tape reader, floppy drive and other devices; determine the installation, connection status and performance of the specified equipment: Some systems can also diagnose certain important chips, such as PAM, ROM, dedicated LSI, etc. The self-diagnosis of the CNC system is performed when it is turned on. Only when all items are confirmed to be correct can it enter the normal operating state. The diagnostic time of a cnc machining aluminum 5052-alloy generally only takes a few seconds, but some may take several minutes. Power-on self-diagnosis is generally carried out according to the prescribed steps. Taking the FANUC II system of FANUC Company as an example, during the execution of the diagnostic program, the seven-segment display on the system motherboard presses 9→8→7→6→5→4→3→2→ The sequence of 1 changes, and the corresponding inspection content is: 9-Reset the CPU and start executing diagnostic instructions: 8-Perform ROM test, indicating that the ROM check error occurs, the display changes to b; 7-Clear the RAM, and the system resets the RAM Clear the contents in and prepare for normal operation; 6. Initialize a pair of BAC (bus random control) chips. At this time, if the display changes to A, it means there is an error in the transmission between the motherboard and the CRT; if it changes to C, it means a connection error; if it changes to F, it means the I/O board or the connecting cable is defective; if it changes to H, it means the used The connection unit identification number is incorrect; a lowercase letter c indicates an optical cable transmission error; a J indicates a defective PLC or interface conversion circuit, etc. 5 – Check the MDI unit 4 – Initialize the CRT unit 3 – Display the initial screen of the CRT, such as software version number, serial number, etc. At this time, if the display changes to L, it indicates that there is a problem with the PLC control software; if it changes to O, it means that the system failed to pass initialization and there is a problem with the control software: 2-Indicates that the initialization of the system has been completed; 1-Indicates that the system is functioning normally If the display changes to E during operation, it means that the system’s main board or ROM board, or the CNC control software is faulty. Under normal circumstances, after the CRT initialization is completed, if there is a fault in other parts, the CRT can display an alarm message.

2. Online monitoring Online monitoring can be divided into two forms: CNC internal program monitoring and monitoring through external equipment. CNC internal program monitoring is a method of automatically diagnosing, checking and monitoring the status of each part through the system’s internal program. The scope of online monitoring includes the CNC itself and the servo units, servo motors, spindle servo units, spindle motors, external equipment, etc. connected to the CNC. Online monitoring is always effective during system operation. The internal program monitoring of the CNC system includes three aspects: interface signal display, internal status display and fault display.

⑴ Interface signal display It can display the current status of all interface signals between CNC and PLC, precision cnc turning 440c blade and machine tool. Refers to the on-off status of digital input/output signals to help analyze faults. During maintenance, it is necessary to understand the meaning of each signal between CNC and PLC, CNC and machine tool, as well as the various conditions for signal generation and cancellation in order to carry out corresponding inspections. The “Function Manual” and “Connection Manual” provided by the CNC system manufacturer and the “Machine Tool Electrical Schematic Diagram” provided by the machine tool manufacturer are technical guides for the above status inspection.

⑵ Internal status display Generally speaking, the following aspects can be displayed using the internal status display function:

1) External reasons that cause the cycle instruction (processing program) to not be executed. For example: whether the CNC system is in the “in-position check” state: whether it is in the “machine tool lock” state: whether it is in the “waiting for speed arrival” signal: whether it is waiting for the measurement signal of the “position encoder” when programming each spindle revolution. ; During thread laser cutting paper, whether it is waiting for the “spindle I rotation signal”, whether the feed speed override is set to 0%, etc.

2) Reset status display, indicating whether the system is in the “emergency stop” state or the “external reset” signal is on.

3) TH alarm status display. It can display the position of the paper tape error hole when alarming.

4) Display of memory contents and abnormal status of bubble memory.

5) Display of position following error.

6) Control information display of servo actuator part

7) Input pulse display of position measuring components such as encoders and gratings, etc.
1. Power-on self-diagnosis The so-called power-on self-diagnosis refers to the diagnosis automatically performed by the system’s internal diagnostic program when the control system is powered on. It is similar to the computer’s power-on diagnosis. Power-on self-diagnosis can automatically check the key hardware in the system, such as: CPU, memory, I/O unit, CRT/MDI unit, paper tape reader, floppy drive and other devices; determine the installation, connection status and performance of the specified equipment: Some systems can also diagnose certain important chips, such as PAM, ROM, dedicated LSI, etc. The self-diagnosis of the CNC system is performed when it is turned on. Only when all items are confirmed to be correct can it enter the normal operating state. The diagnostic time of a CNC system generally only takes a few seconds, but some may take several minutes. Power-on self-diagnosis is generally carried out according to the prescribed steps. Taking the FANUC II system of FANUC Company as an example, during the execution of the diagnostic program, the seven-segment display on the system motherboard presses 9→8→7→6→5→4→3→2→ The sequence of 1 changes, and the corresponding inspection content is: 9-Reset the CPU and start executing diagnostic instructions: 8-Perform ROM test, indicating that the ROM check error occurs, the display changes to b; 7-Clear the RAM, and the system resets the RAM Clear the contents in and prepare for normal operation; 6. Initialize a pair of BAC (bus random control) chips. At this time, if the display changes to A, it means there is an error in the transmission between the motherboard and the CRT; if it changes to C, it means a connection error; if it changes to F, it means the I/O board or the connecting cable is defective; if it changes to H, it means the used The connection unit identification number is incorrect; a lowercase letter c indicates an optical cable transmission error; a J indicates a defective PLC or interface conversion circuit, etc. 5 – Check the MDI unit 4 – Initialize the CRT unit 3 – Display the initial screen of the CRT, such as software version number, serial number, etc. At this time, if the display changes to L, it indicates that there is a problem with the PLC control software; if it changes to O, it means that the system failed to pass initialization and there is a problem with the control software: 2-Indicates that the initialization of the system has been completed; 1-Indicates that the system is functioning normally If the display changes to E during operation, it means that the system’s main board or ROM board, or the CNC control software is faulty. Under normal circumstances, after the CRT initialization is completed, if there is a fault in other parts, the CRT can display an alarm message.

2. Online monitoring Online monitoring can be divided into two forms: CNC internal program monitoring and monitoring through external equipment. CNC internal program monitoring is a method of automatically diagnosing, checking and monitoring the status of each part through the system’s internal program. The scope of online monitoring includes the CNC itself and the servo units, servo motors, spindle servo units, spindle motors, external equipment, etc. connected to the CNC. Online monitoring is always effective during system operation. The internal program monitoring of the CNC system includes three aspects: interface signal display, internal status display and fault display. ⑴ Interface signal display It can display the current status of all interface signals between CNC and PLC, CNC and machine tool. Refers to numerical input