The reasons for vibration marks on CNC vertical lathes may involve many aspects. The following are some possible reasons:

1. Spindle bearing problem: The spindle bearing of the CNC vertical lathe may be faulty or improperly adjusted, causing vibration during the machining process, thereby forming vibration patterns on the surface of the workpiece.

2. Poor tool condition: CNC vertical turning tools may be blunt or the tool shank extends too long, which will affect the stability of the cutting process and lead to the generation of vibration marks.

3. Coordinate axis clearance problem: If the coordinate axis clearance of a CNC vertical lathe is too large or too small, it may affect the machining accuracy and lead to the appearance of vibration marks.

4. System problems: Factors such as unstable operating voltage of the CNC vertical lathe, unreasonable CNC system parameter settings, external interference to the system, etc. may cause the system to lose synchronization and thereby produce vibration marks.

5. Insufficient equipment rigidity: Insufficient rigidity of the CNC vertical lathe will reduce the stability during processing and easily produce vibration and chatter marks.

6. Workpiece material and forming method: CNC vertical lathe workpieces of different materials and forming methods may have different effects on the processing process, which in turn affects the generation of vibration marks.

7. Cutting vibration: Vibration during CNC vertical lathe cutting may be caused by unreasonable cutting parameters, changes in cutting force, etc. This is also an important factor in the generation of vibration marks.

In order to solve the problem of vibration marks caused by CNC vertical lathes, the following aspects can be considered and adjusted:

1. Check and adjust the spindle bearing to ensure that the CNC vertical lathe is in good working condition.

2. Regularly check and replace tools for CNC vertical lathes to keep the tools sharp and adjust the length of the tool shank.

3. Adjust the clearance of the CNC vertical lathe coordinate axis to a reasonable range.

4. Set and optimize the parameters of the CNC vertical lathe CNC system to ensure stable operation of the system.

5. Improve the rigidity of CNC vertical lathe and reduce vibration during processing.

6. Select the appropriate workpiece material and forming method for CNC vertical lathe to optimize the processing process.

7. CNC vertical lathe should set cutting parameters reasonably to reduce cutting vibration.

To sum up, there are many reasons for vibration marks on CNC vertical lathes, which need to be investigated and solved according to specific circumstances. In actual operation, various factors should be considered in combination with the actual situation of the equipment and processing requirements to find the best solution.