Grinding machine static pressure NSK bearing maintenance method

Static pressure NSK bearings have high rotation precision, good rigidity, high bearing capacity, no wear and high durability.

1. Small hole throttle:

(1). Change the internal throttling to external throttling, and add a pressure gauge to instantly display the upper and lower chamber pressure. 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. Thin film feedback throttle:

The film feedback throttling NSK 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).

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Analysis of Rolling Noise Analysis of IKO Bearings

The rolling sound is caused by the rolling of the rolling elements in the raceway when the IKO bearing rotates to excite a smooth and continuous noise, which only attracts attention when its sound pressure level or tone is extremely large. In fact, the sound energy excited by the raceway sound is limited. For example, under normal conditions, the quality of the 6203IKO bearing raceway is 25 to 27 dB. This type of noise is the most typical of single row deep groove IKO bearings that can withstand radial loads. It has the following characteristics:

a. Noise and vibration are random;

b. The vibration frequency is above 1 kHz;

c. Regardless of the change in the rotational speed, the main frequency of the noise is almost constant and the sound pressure level increases as the rotational speed increases;

d. When the radial clearance increases, the sound pressure level increases sharply;

e.IKO bearing housing rigidity increases, the lower the total sound pressure level, even if the speed increases, its total sound pressure level does not increase much;

f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.

The rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even if IKO bearing parts are processed using the most advanced manufacturing techniques in the world, there will always be small geometric errors in the working surface, which will cause small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.

Although the raceway noise of IKO bearings is unavoidable, in the high-precision machining of the working surface of the parts, the IKO bearing is correctly selected and the IKO bearing is accurately used to reduce noise and vibration.

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