What should be done when encountering issues with excessively high temperature of CNC lathe bearings?

The guide bearing of the CNC lathe has an excessively high temperature. Burning problems are common faults. The following discusses how to handle the excessive temperature of the CNC lathe guide bearing.
1. Role of the guide bearing
The purpose of installing the guide bearing of the CNC lathe is to limit the spindle of the generator to operate and bear the radial load on the spindle within the defined movement range of the guide bearing.
2. Working principle of the guide bearing
The working principle of the thin oil film bearing mainly uses high-speed rotation. Lubricating oil enters the contact surface of the bearing and shaft to lubricate the bearing. The hot oil after lubrication is cooled by the oil cooling system and then enters the contact surface of the bearing and shaft. Through the movement of the device, the lubricating oil is automatically cooled in a circulating manner. A stable oil film forms between the shaft and the bearing surface when the spindle rotates, thus bearing the radial load and transmitting it to the guide bearing and then to the base.

3. Components of the guide bearing
The guide bearing of the CNC lathe is a thin oil film bearing mainly consisting of a bearing cover, lubricating oil tank, cooling system, oil return pipe, bearing, bearing seat, bearing fixing screws, thermometer, and other auxiliary parts. The guide bearing of the two units at station B is divided into eight bearings evenly distributed around the circumference on the main guide shaft of the generator.
4. Analysis of causes of increased bearing temperature and increased unit vibration
From observing the operating conditions and analyzing maintenance situations, we believe the main causes of increased bearing temperature and increased equipment vibration fall into two categories:
① The bearing clearance increases significantly beyond the designed clearance, so the lubricating oil cannot easily form an oil film after entering the guide bearing surface, causing poor lubrication, resulting in increased guide bearing temperature and increased unit vibration.
② Insufficient contact points on the bearing surface, inadequate contact area, not meeting equipment standards.
5. Recommendations for solving the increased bearing temperature problem
According to the manufacturer's design specifications, when the CNC lathe operates continuously, the maximum coolant temperature must not exceed 25 ℃, the maximum watt temperature and oil temperature must not exceed 65 ℃. The high and low temperatures of the bearing and oil are related not only to the coolant temperature but also to the lubrication oil circulation conditions and the clearance conditions of the main shaft and shaft.
The allowable clearance of the CNC lathe guide bearing is 0.2~0.3 mm (double-sided clearance). The lower part of the load-bearing shaft is immersed in lubricating oil. When the main shaft rotates clockwise, lubricating oil easily enters the guide bearing surface and forms an oil film to lubricate the bearing surface. Even when passing the peak swing point of the main shaft, although the working clearance is minimal, due to the short clearance, lubrication conditions are good, friction generates little heat, and cooling performance is good. Generally, this does not cause increased bearing temperature phenomena or bearing burning.