CNC machine tools may encounter a variety of faults during use. The following are some common faults and their troubleshooting and solutions:
1. Spindle fault
1. 1The spindle temperature rises sharply
Fault cause: The preload force of the CNC machine tool spindle bearing is too large, or the spindle bearing is damaged, or the spindle lubricating oil is dirty or has impurities, or the spindle bearing lubricating grease is exhausted or excessive.
Solution: Re-adjust the preload force of the CNC machine tool spindle bearing; replace new bearings; clean the spindle box, re-change the oil; re-apply grease.
1.2The spindle torque is insufficient and the machine tool automatically stops
Fault cause: The transmission belt connecting the CNC machine tool spindle motor and the spindle is too loose, has oil, and has failed due to long-term use, or the clutch and coupling connection in the spindle transmission mechanism is too loose or worn.
Solution: Re-adjust the tension of the CNC machine tool spindle drive belt; clean it with gasoline or alcohol; replace a new spindle drive belt; adjust or replace the clutch or coupling.
2. Tool clamping/releasing failure
2.1The tool cannot be clamped
Cause of the failure: The displacement of the disc spring of the CNC machine tool is too small, the spring chuck is damaged, the disc spring fails, and the pull nail on the tool handle is too long.
Solution: The CNC machine tool adjusts the disc spring stroke length; replaces the new spring chuck; replaces the new disc spring; adjusts or replaces the pull nail, and installs it correctly.
2.2The tool cannot be released
Cause of the failure: The pressure and stroke of the hydraulic cylinder of the CNC machine tool are insufficient, and the disc spring is pressed too tightly.
Solution: Adjust the hydraulic pressure and stroke switch position of the CNC machine tool; adjust the nut on the disc spring to reduce the spring pressing amount.
3. The machine tool cannot return to zero point
3.1 Cause of the failure
The contact of the origin switch of the CNC machine tool is stuck and cannot move.
The origin block cannot press the origin switch to the switch action position.
The water in the origin switch causes the switch contacts to rust and have poor contact.
The PLC input point is burned out.
3.2 Solution
Clean the stuck part of the CNC machine tool to make its moving part move smoothly, or replace the travel switch.
Adjust the installation position of the CNC machine tool travel switch so that the zero switch contact can be smoothly pressed to the switch action position by the block.
Replace the CNC machine tool travel switch and take waterproof measures.
Check whether the switch circuit is open or short-circuited, whether there is a signal source (+24V DC power supply); replace the input point on the I/O board, set the parameters, and modify the PLC program.
4. Processing accuracy problem
4.1 The workpiece size is accurate and the surface finish is poor
Cause of failure: The tip of the CNC machine tool is damaged, the machine tool resonates or is placed unsteadily, the machine tool has creeping phenomenon, and the processing technology is not good.
Solution: Re-sharpen the tool or choose a better tool to re-set the tool; adjust the level, lay the foundation, and fix it steadily; clean the wire and add lubricating oil in time; choose a coolant suitable for workpiece processing, and try to use a higher spindle speed.
4.2The workpiece produces a taper head phenomenon
Cause of failure: The CNC machine tool is not placed steadily, and the tailstock ejector pin is not concentric with the spindle.
Solution: Use a level to adjust the level of the CNC machine tool, lay a solid foundation, and fix the machine tool; select a reasonable process and appropriate cutting feed; adjust the tailstock.
4.3The drive phase light is normal, and the workpiece size is sometimes large and sometimes small
Cause of failure: The rapid positioning speed is too fast, the mechanical parts are worn or stuck, the tool holder is too loose after the tool change, and the system parameters are set incorrectly.
Solution: Appropriately adjust the speed of GO, cutting acceleration and deceleration and time; readjust and repair the mechanical parts; check the inside of the tool holder; modify the program, select a reasonable processing technology; check whether the system parameters are set reasonably.
5. Program and software failure
Cause of failure: CNC machine programming error, improper operation, and abnormal control system software.
Solution: Check the CNC machine tool and modify the program; operate according to the operating specifications; contact professionals to check and repair the control system software.
6. Human factor failure
Cause of failure: misoperation, improper maintenance, and improper repair. Solution: Strengthen training to improve the skills of CNC machine operators; formulate and implement strict maintenance plans; ensure that the maintenance process complies with the specifications.
In summary, common faults of CNC machine tools involve many aspects, requiring operators and maintenance personnel to have rich experience and professional knowledge to troubleshoot and solve them. In actual operation, the operating procedures should be strictly followed, and the daily maintenance and maintenance of the equipment should be strengthened to reduce the occurrence of faults.
