How to Deal with the High Temperature Problem of 4-Axis CNC Milling？

High bearing temperature in 4-axis CNC milling is a common problem in lathe. Next, let's talk about how to deal with the high temperature problem of 4-axis CNC milling bearings.

1. the role of guide bearings

The purpose of the CNC lathe rail bearing setup is to limit the work of the generator spindle, so that it can only bear the radial load on the generator spindle within the specified rail bearing clearance range.

2. Working principle of guide bearing

The working principle of the thin oil lubricated block bearing is mainly that when the unit is rotating at a high speed, the lubricating oil is used to enter the joint surface of the bearing bush and the journal to lubricate the bearing bush. After cooling by the oil cooler, the lubricated hot oil enters the joint surface of the bearing bush and the journal again. With the operation of the unit, the lubricating oil is automatically cooled through the reciprocating cycle. A stable oil wedge is formed between the journal and the bushing surface to bear the radial load and transfer it to the guide housing and then to the frame.

3. the composition of guide bearings

CNC lathe guide bearing is a kind of thin oil lubricated block tile bearing, mainly by bearing cover, lubricating oil box, cooler, return oil pipe, bearing sleeve, bearing seat load screw, thermometer and so on. The guide bushings of the two units at station B are divided into eight guide bushings, which are evenly distributed on the guide journal of the generator main shaft according to the circumference.

4. bearing temperature rise and unit vibration increase reason analysis

Through operation observation and maintenance analysis, it is considered that there are two main reasons causing the temperature rise of CNC machine tool bearing and unit vibration:

(1) The increase of bearing clearance is far greater than the design requirements of the clearance, resulting in lubricating oil into the bearing tile surface is not easy to form an oil wedge, resulting in poor lubrication resulting in the guide bearing temperature rise, unit vibration increase;

(2) The contact point of the surface of the shaft tile is small, and the contact surface is insufficient, which does not meet the requirements of the equipment specifications.

5. The solution of temperature rise of guide bearing

According to the design requirements of the manufacturer, when the CNC lathe is continuously running, the maximum temperature of the cooling water should not exceed 25 ° C, and the maximum temperature of the ceramic tile temperature and oil temperature should not exceed 65 ° C. The variation of wattage and oil temperature is not only related to the temperature of cooling water, but also to the circulation of lubricating oil and the clearance between the spindle shaft and the journal.

The allowable clearance of the 4-axis CNC milling bearing is 0.2~ 0.3mm (two-way clearance), and the lower part of the bearing is immersed in lubricating oil. When the spindle is running clockwise, the lubricating oil can easily enter the bearing surface of the guide bearing and produce an oil wedge. When lubricating the surface of the ceramic tile, even through the maximum swing point of the spindle, although the matching gap is minimal, due to the short distance, good lubrication conditions, less heat generated by friction, and good cooling effect, it generally does not lead to the bearing temperature rise phenomenon, nor will it lead to the burning of the ceramic tile.