During the operation of a cam CNC lathe, the spindle accuracy directly determines the quality of the machined parts, especially for parts such as cams that require high profile accuracy. A decrease in spindle accuracy can lead to an increase in machining errors, seriously affecting production efficiency and product qualification rate. Therefore, quickly and accurately diagnosing and effectively repairing spindle accuracy faults is one of the core tasks of equipment maintenance work.
The diagnosis of decreased spindle accuracy should follow the principle of "from the surface to the inside, simple first and complex later". Firstly, conduct a visual inspection to check for any scratches or wear marks on the end of the spindle, and whether the connecting bolts between the spindle box and the bed are loose. If the bolt becomes loose, it will cause radial runout during spindle operation. It can be tightened with a torque wrench to the standard torque, which is the most common problem that is easy to troubleshoot.
If there are no abnormalities in the appearance inspection, a running status check is required. Detect the radial and end face circular runout of the spindle using a dial gauge, and analyze the root cause of the fault based on the accuracy error of the machined specimen. If the radial runout exceeds the standard, it is mostly caused by bearing wear or excessive clearance, which is a common problem that occurs after long-term high-speed operation of the spindle. Ball wear or damage to the cage of the rolling bearing will destroy the rotational accuracy; If the end face circular runout is abnormal, it may be due to wear of the spindle shoulder end face or a decrease in the accuracy of the flange positioning surface. In addition, the concentricity deviation between the spindle and the motor coupling can also cause vibration, indirectly leading to a decrease in accuracy, which needs to be detected by a laser alignment instrument.
The repair work requires precise measures targeting the root cause of the malfunction. For bearing issues, it is necessary to disassemble the spindle box and replace it with a new bearing that meets the accuracy level. During assembly, a hot fitting process is used to ensure fit accuracy, and the bearing clearance is adjusted to a reasonable range using a feeler gauge. If the wear is on the shaft shoulder or flange, grinding technology can be used to repair the positioning surface and restore its flatness and perpendicularity. To address the concentricity deviation of the coupling, it is necessary to loosen the connecting bolts and adjust the motor position to control the radial and axial deviations of the coupling within the allowable range.
After repair, accuracy verification is required, by retesting the runout with a dial gauge and comparing the accuracy indicators with standard specimens. At the same time, establish a regular maintenance mechanism, regularly clean the spindle box, replenish lubricating grease, avoid impurities from entering the bearing parts, regularly check the concentricity of the coupling and the tightening status of the connecting bolts, and reduce the occurrence of precision decline faults from the source.
In summary, the diagnosis of spindle accuracy faults in cam CNC lathes requires a combination of visual inspection and operational testing. Repair should focus on restoring the accuracy of core components and cooperate with regular maintenance to ensure long-term stable operation of the equipment.