Imported bearings with its high rotary accuracy, good rigidity, high bearing capacity, no wear, high durability.
1. Orifice throttle:
(1) change the internal throttle to external throttle, and add oilless bearing pressure gauge to display the upper and lower chamber pressure instantly.Make maintenance convenient, especially can be very easy to clean regularly, which is the internal throttle can not be compared.
(2). Throttling ratio.The theoretical value of throttling ratio self-lubricated bearings is between 1.2 and 1.5, while 1.25 is preferred based on years of experience.In the maintenance of this copper sleeve sample, the geometric accuracy of the spindle, the geometric accuracy of the front and rear bush, coaxiality, roundness and taper should be strictly controlled to ensure the value.According to the bearing capacity of the machine tool to determine e value (spindle and bush geometric center of the eccentricity), make the best.
(3) when the main shaft is not installed in each oil cavity, the oil column of each oil outlet must be consistent (observation method). If not, the method of changing the orifice of the throttle should be adopted to change its flow rate.Take 4 cavities as an example, the oil column of the lower, left and right cavities is generally between 20 and 25mm, and the diameter of the small hole is 0.25 ~ 0.4mm.
2. Film feedback throttle:
Film feedback throttle bearing stiffness is very large, but in the operation of machine tools often appear in the tile, drawing, pressure drop phenomenon.Film feedback is the most critical film, in practice, the main reason is that the bush holding, hair drawing: (1) plastic deformation of the film;(2) slow feedback.When the external load changes, the film has not reacted, the shaft and the tile has been friction;(3) film fatigue.The film has been used for a long time, and the fatigue deformation is equivalent to changing the feedback parameters.
Good results can be obtained by increasing the thickness of the film and using some fatigue resistant materials.Rigid membrane, preloading and gap reservation are generally adopted.The specific practice is: 1.4mm thick film instead of 4mm thick rigid film, in the lower chamber pad 0.05mm thick tin foil, so that the spindle is adjusted to a higher position than the ideal position of 0.05mm.The purpose is to return to the ideal center exactly when the spindle is stressed (grinding wheel weight, cutting force).
3. Improvement of oil supply system:
In the oil supply system of the hydrostatic bearing, except for the coarse filter and the fine filter, the other components have the protection function to the hydrostatic bearing.The oil supply system is improved on the basis of the original system.
(1) the oil outlet behind the throttle plate is connected with a pressure relay and a pressure gauge (originally in front of the accumulator), so that the operator can see the size of cavity pressure and inlet pressure.When the pressure difference is greater than a certain value, in order to immediately stop, so as not to lock the bush.For example, if the inlet pressure is 2MPa and the outlet pressure is 1.2-1.6mpa, the machine will stop if the pressure is lower than 1.2mpa.
(2) add digital detection device:
There is a clearance of 0.04 ~ 0.05mm between the spindle and the bearing bush of the hydrostatic inlet bearing, and the oil in the clearance has a certain resistance value. If the resistance value changes, the clearance size of the period can be known.Take the spindle as one pole and the bush as the other pole, measure the change of its resistance.The 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 tile.