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15 common fault diagnosis and countermeasures of CNC machining center.

    Ⅰ. Handwheel failure

    reason:
    1.Poor contact of handwheel shaft selector switch
    2. Poor contact of handwheel override selector switch
    3. The handwheel pulse generator is damaged
    4 .Broken handwheel cable

    Ⅱ. X Y Z axis and spindle box failure

    reason:
    1. Deformation and damage of Y Z axis shield
    2. Y Z axis drive bearing damage
    3 .The service parameters do not match the mechanical properties.
    4. The connection between the service motor and the screw head is deformed, and the axis is different
    5. The upper and lower guide rails of the heavy hammer in the column are loose and offset
    6. Column weight chain and guide wheel wear and vibration
    7. The shaft pulley is not parallel to the motor end pulley
    8. The spindle belt is damaged and deformed

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    Ⅲ. The rail oil pump and the cutting oil pump are faulty

    reason:
    1. The oil level of the rail oil pump is insufficient
    2. The oil pressure valve of the rail oil pump is damaged
    3. The oil circuit of the machine tool is damaged
    4. The filter of the guide rail oil pump is blocked
    5. The quality of the guide rail oil purchased by the customer exceeds the standard
    6. The oil pumping time of the rail oil pump is set incorrectly
    7. The circuit breaker in the overload electric box of the cutting oil pump is tripped
    8. Air leakage from the cutting oil pump joint
    9. The check valve of the cutting oil pump is damaged
    10. Short circuit of the motor coil of the cutting oil pump
    11. Cutting oil pump motor reverse direction

    Ⅳ. Processing failure

    reason:
    1. X Y Z axis backlash compensation is incorrect
    2. X Y Z Looseness to main insert
    3. X Y Z bearings are damaged
    4. Deviation of the mechanical geometric accuracy of the fuselage
    5. Spindle axial and radial play
    6. Improper adjustment of system servo parameters and processing parameters
    7. Error in customer programming
    8. X Y Z axis screw, nut worn

    Ⅴ. Loosen knife failure

    reason:
    1. Broken knife solenoid valve
    2. Spindle punching cylinder is damaged
    3. Damaged spindle spring
    4. Spindle claw damaged
    5. Insufficient air supply for customers
    6. The release button has poor contact
    7. Line is broken
    8. Knife cylinder oil cup is out of oil
    9. Customer shank latin does not meet the required specification

    Ⅵ. The machine tool cannot return to zero

    reason:
    1. The contact of the origin switch is stuck and cannot move
    2. The origin stopper cannot press the origin switch to the switch action position
    3. Water in the origin switch leads to poor contact of the switch contacts
    4. The origin switch circuit is disconnected or the input signal source is faulty
    5. PLC input point burned out
    Countermeasures:
    1. Clean the stuck parts to make the moving parts move smoothly, or replace the travel switch
    2. Adjust the installation position of the travel switch so that the zero-point switch contact can be smoothly pressed to the switch action position by the stopper
    3. Replace the travel switch and take waterproof measures
    4. Check whether there is an open circuit or short circuit in the switch circuit, and whether there is a signal source (+24V DC power supply)
    5. Replace the input points on the I/O board, do the parameter settings, and modify the PLC program

    Ⅶ. Machine tool positive and negative hard limit alarm

    Under normal circumstances, this alarm will not occur, but it may occur when the machine tool is operated before zero return. Before zero return, the system does not have a fixed mechanical coordinate system but can position at random, and the software limit is invalid. Therefore, the zero point must be returned before operating the machine tool.
    reason:
    1. The travel switch contacts are pressed and stuck (overtravel)
    2. Damaged travel switch
    3. Open circuit, short circuit and no signal source in the circuit of the limit switch
    4. The limit stop cannot press the switch contact to the action position
    5. PLC input point burned out

    Ⅷ. Tool change failure

    reason:
    1. Insufficient air pressure
    2. The release button is in poor contact or the circuit is open circuit
    3. The PLC input address point of the knife release button is burned out or there is no signal source (+24V)
    4. Knife release relay does not act
    5. Broken knife solenoid valve
    6. Not enough knife
    7. Knife cylinder oil cup is out of oil
    8. Cylinder failure

    Ⅸ. Abnormal sound when three axes are running

    reason:
    1. faulty bearing
    2. The screw busbar and the guide rail are unbalanced
    3. The wear-resistant sheet is severely worn, resulting in serious scratches on the guide rail
    4. Servo motor gain does not match

    Ⅹ. Lubrication failure

    reason:
    1. Lack of oil in the lubricating pump tank
    2. The lubricating pump oiling time is too short
    3. The pressure relief mechanism of the lubricating pump releases the pressure too fast
    4. Oil leaks in oil pipe
    5. The one-way valve in the oil circuit does not act
    6. Damaged oil pump motor
    7. Damaged lubrication pump control circuit board

    Ⅺ. Tool magazine problem

    reason:
    1. The tool suddenly stops during the tool change, and the tool change cannot be continued
    2. The hat type tool magazine cannot come out
    3. Do not let go of the knife during tool change
    4. The cutter head cannot be rotated
    5. The cutter head suddenly rotates in the opposite direction, and the time difference is half a cutter position
    6. When changing the tool, there is an error alarm for loosening the tool and tightening the tool
    7. When returning the tool during the replacement process, the sound on the spindle side is very loud
    8. After the replacement, the spindle cannot be loaded with the tool (abnormal loosening of the tool)

    Ⅻ. The machine cannot be powered on

    reason:
    1. The three-phase contact of the main power switch is poor or the switch is damaged
    2. The operation panel cannot be powered on

    XIII. Cooling water pump failure

    reason:
    1. Check the water pump for burnout
    2. Whether the power phase sequence is reversed
    3. AC contact, whether the relay is burned out
    4. Panel button switch with or without input signal

    XIV. Air blow failure

    reason:
    1. Check whether the solenoid valve operates
    2. Check whether the blowing relay operates
    3. Whether the panel buttons and PLC output interface have signals
    In the face of these faults in the machining center, it is necessary to carefully analyze the reasons and find solutions. For example, the faults of X, Y, Z axes and the spindle box may be caused by the deformation of the protective cover. At this time, the protective cover should be replaced in time. Return to normal use. The protective cover is a small accessory on the machining center, but it also plays a vital role. A good quality protective cover can reduce the failure rate of the machine tool.

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