How to Repair Grinder Hydrostatic Imported Bearings

1. Small hole throttle: (1). Change the internal throttle to the external throttle, and install the pressure gauge to display the pressure of the upper and lower chambers immediately. Make maintenance easy, especially can be easily cleaned regularly, which is unmatched by internal restrictors.

(2). Throttle ratio. The theoretical value of the throttling ratio β is between 1.2 and 1.5, and according to many years of experience, 1.25 is better. In this way, during the maintenance, it is necessary to strictly control the geometric accuracy of the main shaft, the geometric accuracy of the front and rear bearing bushes, the coaxiality, the roundness and the taper in order to ensure the β value. Determine the value of e (the eccentricity between the spindle and the geometric center of the bearing bush) according to the bearing capacity of the machine tool, so that the value of β is the best.

(3). When the main shaft is not installed in each oil chamber, the oil column of each oil outlet must be consistent (observation method). . Taking 4 chambers as an example, the oil column of the lower, left and right chambers is generally between 20 and 25mm, and the diameter of the small hole is 0.25 to 0.4mm.

2. Membrane feedback throttle:

The rigidity of the membrane feedback throttle bearing is very large, but the machine tool often occurs in the operation of the shoe, pulling, and pressure drop. . The most critical film feedback is the film. In practice, it is believed that the main reasons for the locking and pulling of the bearing pads are: (1) caused by the plastic deformation of the film; (2) the feedback is slow. When the external load changes abruptly, when the film has not reacted, the shaft and the shoe have already rubbed; ③ the film is fatigued. The film is used for a long time, and it is fatigued and deformed, which is equivalent to changing the feedback parameters. Increasing the thickness of the film and switching to some fatigue-resistant materials can achieve good results. Generally, the method of rigid film, preload and reserved gap is used. The specific method is: change the 1.4mm thick film to a 4mm thick rigid film, and place a 0.05mm thick tin foil in the lower cavity to adjust the spindle to a position 0.05mm higher than the ideal position. The purpose is to just return to the ideal center when the spindle is subjected to force (grinding wheel weight, cutting force).

3. Improvement of the oil supply system:

In the oil supply system of the static pressure imported bearing, except for the coarse filter and the fine filter, the other components have a protective effect on the static pressure bearing. The oil supply system is improved on the basis of the original system. (1). The oil outlet behind the throttle plate is connected to a pressure relay and a pressure gauge (originally in front of the accumulator), so that the operator can see the chamber pressure and the inlet pressure. When the pressure difference is greater than a certain value, it can be stopped immediately to prevent the bearing bush from locking. For example, the inlet pressure is 2MPa, the outlet pressure is 1.2-1.6MPa, and the machine will be shut down if it is lower than 1.2MPa.

(2). Increase the digital detection device:

There is a gap of 0.04-0.05mm between the main shaft and the bearing bush of the static pressure imported bearing, and the oil in between has a certain resistance value , to detect the change of this resistance value, you can know the size of the period gap. Take the main shaft as one pole and the bearing bush as the other pole, and measure the resistance change. This signal is processed and sent to the photoelectric alarm and control system amplifier to control the start and stop of the spindle motor, so as to avoid the friction between the shaft and the shoe.