Structure and performance characteristics of fag bearing
Thrust angular contact ball bearing in fag bearing
The contact angle of thrust angular contact ball bearing is generally 60 °. The commonly used thrust angular contact ball bearing is generally a two-way thrust angular contact ball bearing, which is mainly used for the spindle of precision machine tools. It is generally used together with double row cylindrical roller bearing, and can bear two-way axial load. It has the advantages of high precision, good rigidity, low temperature rise, high speed, convenient assembly and disassembly, etc.
Deep groove ball bearing in fag bearing
Structurally, each ring of deep groove ball bearing has a continuous groove raceway with a cross-section of about one-third of the circumference of the equatorial circle of the ball. Deep groove ball bearing is mainly used to bear radial load and certain axial load. When the radial clearance of the bearing increases, it has the property of angular contact ball bearing and can bear the alternating axial load in two directions. Compared with other types of bearings with the same size, this kind of bearing has small friction coefficient, high limit speed and high precision. It is the preferred bearing type for user selection. Deep groove ball bearing has simple structure and convenient use. It is a kind of fag bearing with large production volume and wide application range.
Thrust tapered roller bearing in fag bearing
Because the rolling element in the thrust tapered roller bearing is a tapered roller, the rolling bus and the raceway bus of the washer meet at a certain point on the axis line of the bearing in structure, so the rolling surface can form pure rolling, and the limit speed is higher than that of the thrust cylindrical roller bearing. Features: thrust tapered roller bearing can bear unidirectional axial load. The type code of thrust tapered roller bearing is 90000.
Structure and performance characteristics of double row tapered roller bearing in fag bearing
There are many structures of double row tapered roller bearings, a large number of which are 35000 type. There is a double raceway outer ring and two inner rings. There is a spacer between the two inner rings. The clearance can be adjusted by changing the thickness of the spacer. This kind of bearing can bear both radial load and bidirectional axial load, and can limit the axial displacement of shaft and shell within the range of axial clearance of bearing. Structural characteristics of tapered roller bearing. The type code of tapered roller bearing is 30000, and the tapered roller bearing is a separate bearing. Tapered roller bearings are mainly used to bear the combined radial and axial load dominated by radial load. Compared with the ball bearing, the bearing speed and bearing angle are large. Tapered roller bearing can bear axial load in one direction and limit axial displacement of shaft or shell in one direction.
Hydrostatic NSK bearing has high rotation accuracy, good rigidity, high bearing capacity, no wear and high durability. The following are some experience gained in the exploration and attempt of hydrostatic NSK bearing in the maintenance process, which is for your reference only.
Orifice restrictor:fag bearing
Change the internal throttling into external throttling, and install a pressure gauge to display the pressure of the upper and lower chambers immediately. It makes the maintenance convenient, especially it can be easily cleaned regularly, which is unmatched by the internal throttle.
Throttle ratio. Throttle ratio β The theoretical value of is 1.2 ~ 1.5, and 1.25 is better according to many years of experience. In this way, during maintenance, it is necessary to strictly control the geometric accuracy of the main shaft, the geometric accuracy of the front and rear bearing shells, coaxiality, roundness and taper, so as to ensure β Value. Determine the E value according to the bearing capacity of the machine tool (the eccentricity of the geometric center of the main shaft and bearing bush) β Value.
If the orifice diameter of each oil column is not the same, the orifice diameter of each oil column must be observed. If the orifice diameter of each oil column is not the same, the orifice diameter must be changed. Take 4 cavities as an example. Generally, the oil column of the lower, left and right cavities is between 20 ~ 25mm, and the diameter of the small hole is 0.25 ~ 0.4mm.
Film feedback restrictor:fag bearing
The stiffness of thin film feedback throttling bearing is very large, but the phenomena such as pad holding, roughening and pressure drop often occur in the operation of machine tools. The key of film feedback is film. In practice, it is considered that the main reasons for bearing bush locking and galling are:
plastic deformation of film; ② Feedback is slow. When the external load changes suddenly and the film has not reacted, the shaft and pad have been rubbed; ③ Film fatigue. The film has long service time and fatigue deformation, which 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. Generally, rigid membrane, preloading and reserved gap are adopted. The specific method is: change the 1.4mm thick film into 4mm thick rigid film, pad 0.05mm thick tin foil paper in the lower cavity, and 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 wheel weight, cutting force).
Improvement of oil supply system:fag bearing
In the oil supply system of hydrostatic NSK bearing, except for coarse filtration and fine filtration, other components have a protective effect on hydrostatic bearing. The oil supply system is improved on the basis of the original system.
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 cavity pressure and NSK pressure. When the differential pressure is greater than a certain value, the machine can be shut down immediately to prevent the bearing bush from locking. For example, NSK pressure is 2MPa, outlet cavity pressure is 1.2 ~ 1.6Mpa, and shutdown is required if it is lower than 1.2MPa.
Add digital detection device:
There is a gap of 0.04 ~ 0.05mm between the main shaft and bearing bush of hydrostatic NSK bearing, and the oil in the gap has a certain resistance value.
By detecting the change of this resistance value, we can know the size of the phase gap. Take the main shaft as one pole and the bearing bush as the other pole, and measure the resistance change. After processing, the signal is 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 bearing.
Martensite in quenched steel characteristics of fag bearing
The so-called burn damage state of SKF Bearing refers to that the raceway wheel, rolling element and cage of SKF Bearing are heated sharply during rotation until they change color, soften, deposit and damage.Structure and performance characteristics of fag bearing
The main cause of SKF Bearing burn is that the lubrication of SKF Bearing is poor, and irregular lubricant may be used, or too much or too little lubricant is incorrect.Structure and performance characteristics of fag bearing
The second may be excessive load (excessive preloading). Excessive speed. The clearance is too small. Intrusion of water or other foreign matters. If neither of the above two cases is true, the accuracy of the shaft and SKF Bearing housing is poor and the deflection of the shaft is large. Structure and performance characteristics of fag bearing
First of all, we should study the lubricant and lubrication method, select the right SKF Bearing Lubricant and its dosage, and correct the selection of SKF Bearing. Study the fit, SKF Bearing Clearance and preloading, and improve the sealing device. Check the accuracy of the shaft and SKF Bearing housing.Structure and performance characteristics of fag bearing
The cage is used in the rolling INA Bearing of INA Bearing to isolate the rolling element at an equal distance, prevent the rolling element from falling, and drive the rolling element to rotate. Rolling ina bearing cage can be divided into stamping cage and solid cage. Structure and performance characteristics of fag bearing
When the rolling ina bearing is working, the ina bearing is heated and worn due to sliding friction. Especially under the condition of high-speed operation, the friction, wear and heating are accelerated due to the action of centrifugal force. Structure and performance characteristics of fag bearing
In serious cases, the cage will be burned and broken, resulting in the ina bearing can not be used normally. Cage damage accounts for a large proportion of ina bearing failure. Among the reasons of cage damage, the quality of cage material is one of the main reasons. Therefore, it is required that the rolling ina bearing cage material in ina bearing should have the following properties:
With the combination of strength and toughness, the cage can bear certain load and impact, and has good elasticity and stiffness. The commonly used materials of INA Bearing Cage, rivet, washer, spacer, seal ring, pillar, support pin, etc. are divided into three categories: ferrous materials (such as low carbon steel, stainless steel, etc.), non-ferrous materials (such as brass, bronze and aluminum alloy, etc.) and non-metallic materials (such as phenolic cloth, bakelite, plastic, etc.).Structure and performance characteristics of fag bearing
INA Bearing Cage for special purposes shall also meet the requirements of special working conditions, such as high temperature resistance, corrosion resistance, self-lubricating (used in vacuum) or non-magnetic, etc.Structure and performance characteristics of fag bearing
Stamped cages are often made of steel plate and sometimes copper plate. Compared with the metal solid cage, this cage has the advantage of light weight. The press cage occupies a small gap between the inner and outer rings of INA Bearing, and the lubricating oil is easy to enter INA Bearing and remain in the cage.Structure and performance characteristics of fag bearing
The stamped cage is written into the INA Bearing code only when it is not used as a standard structure.
The solid cage is made of metal, phenolic resin fabric and plastic. These bearing materials are generally indicated in ina.Structure and performance characteristics of fag bearing
Metal solid cages are used in working places with high strength requirements and high temperature.
Solid cages can also be used when retaining edges are required. The high-speed ina bearing cage at the retaining edge is made of light materials, such as light metal or phenolic resin fabric, to ensure its small inertial force.
Polyamide (nylon 66) cage has very good sliding and self-lubricating properties.Structure and performance characteristics of fag bearing
The cage made of glass fiber reinforced nylon 66 is used for stable operation with working temperature not exceeding 120 ~ C. Material factors affecting the service life of imported bearings
The early failure forms of rolling bearing mainly include fracture, plastic deformation, wear, corrosion and fatigue. Under normal conditions, it is mainly contact fatigue. In addition to the service conditions, the failure of imported bearing parts is mainly restricted by the hardness, strength, toughness, wear resistance, corrosion resistance and internal stress state of steel. The main internal factors affecting these performances and states are as follows:
When the original structure of high carbon chromium steel is granular pearlite, the carbon content of quenched martensite obviously affects the mechanical properties of the steel under the condition of quenching and low temperature tempering. The strength and toughness are about 0.5%, the contact fatigue life is about 0.55%, and the compressive collapse capacity is about 0.42%. When the carbon content of quenched martensite of GCr15 steel is 0.5% ~ 0.56%, the comprehensive mechanical properties with strong failure resistance can be obtained.
Retained austenite in quenched steel characteristics of fag bearing
After normal quenching, high carbon chromium steel can contain 8% ~ 20% AR (residual austenite). AR in imported bearing parts has both advantages and disadvantages. In order to promote advantages and eliminate disadvantages, the content of AR should be appropriate.
Since the amount of AR is mainly related to the austenitizing conditions of quenching heating, and its amount will affect the carbon content of quenched martensite and the amount of insoluble carbide, it is difficult to correctly reflect the influence of AR on mechanical properties.
Therefore, the austenite heat stabilization process was used to obtain different ar content under the fixed austenite condition. The effect of AR content on the hardness and contact fatigue life of GCr15 steel after quenching and low temperature tempering was studied. With the increase of austenite content, the hardness and contact fatigue life increase, and then decrease after reaching the peak, but the peak ar content is different. The hardness peak appears at about 17% AR, while the contact fatigue life peak appears at about 9%.
Insoluble carbide in quenched characteristics of fag bearing
The quantity, morphology, size and distribution of undissolved carbides in quenched steel are affected not only by the chemical composition of the steel and the original structure before quenching, but also by the austenitizing conditions. There are few studies on the influence of undissolved carbides on the service life of imported bearings. Carbide is a hard brittle phase.
In addition to being beneficial to wear resistance, it will produce cracks due to stress concentration with the matrix (especially when the carbide is non spherical), which will reduce toughness and fatigue resistance. Quenched insoluble carbides not only affect the properties of steel, but also affect the carbon content and AR content and distribution of quenched martensite, which has an additional impact on the properties of steel.
Therefore, too much quenched insoluble carbide is harmful to the comprehensive mechanical properties and failure resistance of steel. Properly reducing the carbon content of imported bearing steel is one of the ways to improve the service life of parts.Structure and performance characteristics of fag bearing
In addition to the quantity of quenched undissolved carbides, the size, morphology and distribution also affect the properties of the material. In order to avoid the harm of undissolved carbides in imported bearing steel, it is required to have less undissolved carbides (small quantity), small carbides (small size), uniform carbides (the size difference is very small and the distribution is uniform), and round carbides (each carbide is spherical).
It should be pointed out that it is necessary for imported bearing steel to have a small amount of undissolved carbide after quenching, which can not only maintain sufficient wear resistance, but also be a necessary condition for obtaining fine grain cryptocrystalline martensite.Structure and performance characteristics of fag bearing
Residual stress after characteristics of fag bearing
After quenching and low temperature tempering, the imported bearing parts still have large internal stress. The residual internal stress in parts can be divided into advantages and disadvantages. After heat treatment, the fatigue strength of steel increases with the increase of surface residual compressive stress. Structure and performance characteristics of fag bearing
On the contrary, when the surface residual internal stress is tensile stress, the fatigue strength of steel decreases. Therefore, it is also one of the measures to improve the service life to make the surface of imported bearing parts remain large compressive stress after quenching and tempering.Structure and performance characteristics of fag bearing