Static pressure SKF bearings are widely used in M210, M131W, 3160A grinding machines and 2A710, FYT10 diamond boring heads due to their high rotation precision, good rigidity, high bearing capacity, no wear and high durability. With the development of numerical control technology, static pressure SKF bearings are also widely used in the spindles of CNC machines such as machining centers. The first engine plant of Yituo Co., Ltd. has many static pressure grinders and static pressure diamond hoes. Some explorations and attempts have been made in the maintenance and some experience has been gained.
1. The small orifice restrictor (1) changes the internal throttling to the external throttling, and adds a pressure gauge to instantly display the upper and lower chamber pressures. It is easy to maintain, especially it can be cleaned regularly, which is unmatched by the internal throttle. (2) Throttling ratio. The theoretical value of the throttle ratio β is between 1.2 and 1.5, and 1.25 is preferred based on years of experience. In this way, the geometric accuracy of the main shaft, the geometrical accuracy of the front and rear bearing pads, the concentricity, the roundness and the taper need to be strictly controlled in order to ensure the β value. The e value (the eccentricity of the main axis and the geometric center of the bearing bush) is determined according to the load carrying capacity of the machine tool to optimize the β value. (3) When the oil chamber is not equipped with the main shaft, the oil column of each oil outlet must be consistent (observation method). If it is inconsistent, the flow rate should be changed by changing the orifice diameter of the throttle. Taking 4 chambers as an example, the oil column of the lower, left and right chambers is generally between 20 and 25 mm, and the diameter of the small holes is 0.25 to 0.4 mm.
2. Film feedback throttle film feedback throttling SKF bearing stiffness is very large, but the machine tool often appears in the operation of the holding tile, pulling, falling pressure and so on. The most critical of the film feedback is the film. In practice, the main reasons for the bearing lock and pulling are: 1 plastic deformation of the film; 2 slow feedback. When the external load is abrupt, the shaft and the tile have already rubbed when the film has not reacted; 3 the film is fatigued. The film is used for a long time and fatigue deformation, which is equivalent to changing the feedback parameters. Increased film thickness and the use of some fatigue-resistant materials can achieve good results. Generally, a rigid film, a preload, and a gap are reserved. 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 return to the ideal center just after the spindle is stressed (grinding weight, cutting force).
3. Improved static pressure of the oil supply system In the SKF bearing oil supply system, except for the coarse filter and the fine filter, the other components have a protective effect on the static pressure SKF bearing. The oil supply system is improved on the basis of the original system. (1) Connect the pressure relay and pressure gauge (originally in front of the accumulator) at the oil outlet behind the throttle plate so that the operator can see the pressure of the chamber and the inlet pressure. When the pressure difference is greater than a certain value, in order to stop immediately, so as to avoid the axle lock. Such as: the inlet pressure 2MPa, the oral pressure 1.2 ~ 1.6MPa, less than 1.2MPa will stop. (2) Increasing the digital detection device Static pressure SKF bearing between the main shaft and the bearing bush has a gap of 0.04 ~ 0.05mm, the oil in the process has a certain resistance value, detect the change of this resistance, you can know the period gap size. Take the main shaft as one pole and the bearing bush as the other pole, and measure its 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 to avoid the friction between the shaft and the tile.Some experience in the maintenance of grinding machine static pressure SKF bearing
Static pressure SKF bearings are widely used in M210, M131W, 3160A grinding machines and 2A710, FYT10 diamond boring heads due to their high rotation precision, good rigidity, high bearing capacity, no wear and high durability. With the development of numerical control technology, static pressure SKF bearings are also widely used in the spindles of CNC machines such as machining centers. The first engine plant of Yituo Co., Ltd. has many static pressure grinders and static pressure diamond hoes. Some explorations and attempts have been made in the maintenance and some experience has been gained.
1. The small orifice restrictor (1) changes the internal throttling to the external throttling, and adds a pressure gauge to instantly display the upper and lower chamber pressures. It is easy to maintain, especially it can be cleaned regularly, which is unmatched by the internal throttle. (2) Throttling ratio. The theoretical value of the throttle ratio β is between 1.2 and 1.5, and 1.25 is preferred based on years of experience. In this way, the geometric accuracy of the main shaft, the geometrical accuracy of the front and rear bearing pads, the concentricity, the roundness and the taper need to be strictly controlled in order to ensure the β value. The e value (the eccentricity of the main axis and the geometric center of the bearing bush) is determined according to the load carrying capacity of the machine tool to optimize the β value. (3) When the oil chamber is not equipped with the main shaft, the oil column of each oil outlet must be consistent (observation method). If it is inconsistent, the flow rate should be changed by changing the orifice diameter of the throttle. Taking 4 chambers as an example, the oil column of the lower, left and right chambers is generally between 20 and 25 mm, and the diameter of the small holes is 0.25 to 0.4 mm.
2. Film feedback throttle film feedback throttling SKF bearing stiffness is very large, but the machine tool often appears in the operation of the holding tile, pulling, falling pressure and so on. The most critical of the film feedback is the film. In practice, the main reasons for the bearing lock and pulling are: 1 plastic deformation of the film; 2 slow feedback. When the external load is abrupt, the shaft and the tile have already rubbed when the film has not reacted; 3 the film is fatigued. The film is used for a long time and fatigue deformation, which is equivalent to changing the feedback parameters. Increased film thickness and the use of some fatigue-resistant materials can achieve good results. Generally, a rigid film, a preload, and a gap are reserved. 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 return to the ideal center just after the spindle is stressed (grinding weight, cutting force).
3. Improved static pressure of the oil supply system In the SKF bearing oil supply system, except for the coarse filter and the fine filter, the other components have a protective effect on the static pressure SKF bearing. The oil supply system is improved on the basis of the original system. (1) Connect the pressure relay and pressure gauge (originally in front of the accumulator) at the oil outlet behind the throttle plate so that the operator can see the pressure of the chamber and the inlet pressure. When the pressure difference is greater than a certain value, in order to stop immediately, so as to avoid the axle lock. Such as: the inlet pressure 2MPa, the oral pressure 1.2 ~ 1.6MPa, less than 1.2MPa will stop. (2) Increasing the digital detection device Static pressure SKF bearing between the main shaft and the bearing bush has a gap of 0.04 ~ 0.05mm, the oil in the process has a certain resistance value, detect the change of this resistance, you can know the period gap size. Take the main shaft as one pole and the bearing bush as the other pole, and measure its 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 to avoid the friction between the shaft and the tile.
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