Maintenance and treatment measures for common faults of mechanical spindles

1. **Failure Phenomenon of Spindle Heating and Reduced Rotational Accuracy**: During machining, the workpiece's hole accuracy is low, with poor cylindricity. The spindle overheats rapidly, and the machining noise is significant. **Cause Analysis**: Observations over time revealed that the centering cone hole of the spindle was damaged due to multiple tool changes. This was primarily caused by errors in the tool-pulling process, which damaged the spindle’s conical surface. Further inspection confirmed four main issues: - The lubricating grease for the spindle bearing did not meet standards, containing dust, impurities, and moisture. These contaminants were introduced via the unfiltered and undried compressed air used in the machining center. This led to inadequate lubrication and excessive heat generation, accompanied by significant noise. - Damage to the conical hole's positioning surface resulted in imperfect alignment between the spindle and the tool holder, causing slight eccentricity in the machined holes. - The preload force of the front bearing decreased, increasing the bearing clearance. - Fatigue in the spring of the automatic clamping device prevented the tool from being securely fastened, causing positional deviation. **Troubleshooting Measures**: - Replace the front bearing of the spindle, use approved grease, and adjust the bearing clearance. - Grind the conical hole’s positioning surface to ensure at least 90% contact with the tool holder. - Replace the clamping device spring and adjust the bearing preload force. In addition, regular checks of the spindle’s shaft-hole and tool-holder alignment are necessary, along with adding an air filtration and drying device. Processing techniques should be optimized to avoid overloading the machine. 2. **Damage to Steel Balls in the Spindle Component**: The steel balls in the automatic clamping mechanism of the machining center often get damaged, along with the tapered surface of the tool handle. **Cause Analysis**: Research showed that the spindle loosening action was out of sync with the robot’s pulling action. Specifically, the limit switch was placed at the booster cylinder’s tail. When the cylinder piston reached its position, the booster cylinder piston was not aligned, leading to violent pulling of the tool before the robot fully loosened the clamp. This severely damaged the puller steel balls and tensioning screws. **Fault Handling Measures**: Clean the oil cylinder and booster cylinder, replace the sealing rings, and adjust the pressure to synchronize both actions. Regular inspections of the gas-liquid booster cylinder are also essential to eliminate potential risks. 3. **Failure of Positioning Keys in Spindle Components**: During tool changes, there is loud noise, and the positioning keys at the front end of the spindle that rotate the tool handle are partially deformed. **Cause Analysis**: Studies found that the noise occurred during the tool-insertion phase of the manipulator, due to errors in the spindle's correct stop position and drifting at the reference point. The Hall elements' fixing screws became loose over time, causing misalignment between the tool handle keyway and the spindle positioning key. Additionally, drifting of the reference point might result from poor contact in the CNC system’s circuit board, electrical parameter changes, or loose proximity switches. This drifting caused the tapered surface to collide with the centering cone hole, generating abnormal noise. **Troubleshooting Measures**: Adjust the Hall element's installation position, secure it with anti-loosening glue, and recalibrate the tool-change reference point. Replace the positioning keys at the spindle’s front end. Regularly inspect the spindle’s stop position and tool-change reference point, addressing any anomalies promptly. **Maintenance of Mechanical Spindles**: To reduce bearing temperatures, lubrication is critical. Two primary methods include oil and gas lubrication and oil circulation lubrication. When implementing these: - Ensure the oil volume in the spindle’s constant-temperature oil tank is sufficient for circulation lubrication. - For oil and gas lubrication, only ten percent of the bearing space should be filled. The benefits of circulating lubrication include reduced frictional heat and absorption of some spindle assembly heat. Spindle lubrication also employs oil mist and injection methods, focusing on reducing bearing heat and controlling heat sources. Sealing the spindle components prevents dust, chips, and coolant ingress while stopping lubricant leaks. Contact seals (like lip seals and oil-resistant rubber) require monitoring for aging or damage, whereas non-contact seals must ensure quick oil drainage and clear return oil holes to prevent leaks. Proper lubrication reduces bearing temperatures and extends lifespan. During operation, grease or oil circulation is suitable, while oil mist or oil gas is ideal at high speeds. Excessive grease can worsen spindle heating, so the bearing space volume should be filled to only 10%. Regular checks of the spindle lubrication constant-temperature oil tank ensure adequate oil levels and appropriate temperature ranges. Mechanical spindles are characterized by high speed, high accuracy, high efficiency, and low noise.

Korean Type Heavy Duty Industrial Caster

Korean Type Heavy Duty Industrial Caster

Korean Type Heavy Duty Industrial Caster

Ningbo Mywin Caster Co., Ltd. , https://www.mywin-caster.com