Common Faults and Troubleshooting Methods of Double-spindle CNC Lathes

As a high-precision processing equipment, the faults of the double-spindle CNC lathe mainly fall into four categories: mechanical, electrical, hydraulic and control system. The following are various common faults and their corresponding troubleshooting methods:

I. Mechanical failure

Tool rest failure ‌

Excessive preload: It is manifested as excessive resistance when rotating the end of the worm with a wrench. This can be eliminated by reducing the clamping current of the tool rest motor

Mechanical jamming ‌ : Check whether the reverse alignment pin is in the reverse alignment ratchet slot, whether the main shaft nut is locked, and perform lubrication treatment

Pin breakage or hall element damage ‌ : this accounts for 80% of tool rest faults. It is necessary to check the pin mobility and the voltage stability of the hall element

2. Abnormal noise from the spindle box

Common causes include deformation of the protective cover pressing on the guide rail, and the servo motor not being coaxial with the lead screw, etc

Processing procedure: Calibrate servo parameters - Detect bearing wear - calibrate the coaxiality of the motor and lead screw

3. Feed drive chain failure

It is manifested as a decline in motion quality, a reduction in positioning accuracy, an increase in backlash, etc

The main components to be inspected include the roller lead screw pair, the hydrostatic lead screw nut pair, the rolling guide rail, etc

Ⅱ. Electrical Faults

 handwheel malfunctioning ‌

Three key inspection points: poor contact of the shaft selector switch, damage to the pulse generation disk or breakage of the connecting wire

It is necessary to enter the system diagnosis interface to check the on-off status of the switch contacts and the circuit ‌

2.Power module failure ‌

Damage to the rectifier bridge, short circuit of the freewheeling diode, damage to the filter capacitor, etc

Check whether the external power supply is missing a phase or short-circuited, and whether the protection device has tripped

3.

Servo system anomaly ‌

Motor overload, excessive temperature rise or internal winding damage

Loose or damaged encoder connection causes inaccurate position feedback ‌

Ⅲ. Hydraulic Failure

1.oil pump stops ‌

Insufficient oil pressure leads to a decrease in the accuracy of the machine tool. It is necessary to check the oil level, oil pressure valve, oil circuit and filter screen

Pay special attention to using the type of guide rail oil (‌) recommended by the manufacturer

2.

Hydraulic system leakage ‌

Internal leakage (on both sides of the hydraulic cylinder piston) and external leakage (between the system and the environment)

Solution: Use high-quality sealing parts, improve processing accuracy, and control oil temperature ‌

3.

The ‌ slider crawls ‌

Cause: Air accumulation in the system or pump suction, improper precision adjustment

Troubleshooting method: Check if the suction pipe of the pump is taking in air. Move it up and down several times and apply pressure ‌

Iv. Control System failure

1.The ‌ program is running abnormally ‌

Software conflicts or hardware failures (damage to memory sticks, hard disks or motherboards)

It is necessary to check the system upgrade record and program loading status ‌

2.

Spindle emergency stop ‌

The drive belt is too loose, has oil on its surface or has failed due to prolonged use

Loose or worn clutch and coupling connections can also cause this problem ‌

3.

The tool cannot be clamped ‌

The displacement of the disc spring is too small, the spring chuck is damaged or the pull pin is too long

The spring stroke length needs to be adjusted or the damaged part ‌ needs to be replaced

General steps for fault diagnosis

Inquiry and investigation ‌ : to gain a detailed understanding of the fault phenomenon, occurrence time and operation mode ‌

On-site inspection ‌‌ : observe the contents of the alarm display, working register and buffer register ‌

Fault reproduction ‌ : Attempt to reproduce the fault phenomenon ‌ without endangering safety

System diagnosis ‌‌ : Use the diagnostic screen to check the working status of the machine tool and the position of the coordinate axes ‌

 ‌