What are the characteristics of porous powder metallurgy materials?

     Porous is one of the important features of powder metallurgy materials. With this feature, (1) can make sweating materials. That is, the low-melting substance is impregnated in the pores of the ordinary powder metallurgy material, and when the high-temperature work is performed, the impregnated material melts and oozes, so that the material "sweating" to dissipate heat. This makes it possible to replace expensive heat-resistant alloys with ordinary materials and further increase the service temperature of heat-resistant parts. (2) Manufacturing filter materials. Used for filtration, filtrate and filtration. (3) Impregnating and reducing abrasives to produce oil- and oil-free lubricating bearings; impregnating spices to make fragrant handicrafts. (4) In some cases, iron is used instead of non-ferrous metals such as copper and lead. (5) Manufacturing materials such as vibration damping, noise reduction, and heat insulation. (6) Increasing the specific surface area of the material, and using it as a carrier for the substance (such as carrying a catalyst, etc.).https://www.supplyforever.com/

TIMKEN bearing preload related knowledge

If you want to understand the bearing in depth, you must go through a painstaking learning process. Because this knowledge is profound and profound, now I will briefly introduce some knowledge of timken bearings, and I hope that it will help you in your future work.
The significance of TIMKEN bearing preload
The preload of the TIMKEN bearing is used to allow the bearing to be used with a negative clearance. This method of use is called preloading. It is more suitable for radial thrust ball bearings, tapered roller bearings, and the two bearings are used opposite each other to become a bearing that can adjust the clearance.
First, the main purpose of TIMKEN bearing preload:
1. Suppress the runout of the shaft while correctly determining the position of the radial direction and the axial direction of the shaft.
2. Improve the rigidity of the bearing. The main shaft of the machine tool is used for bearing, and the differential gear of the bicycle is used for the TIMKEN imported bearing.
3. Prevent vibration in the axial direction and abnormal sound caused by resonance. Suitable for bearings for small motors.
4. Suppress the rotation and sliding of the rolling elements, the revolutionary sliding and the self-rotating sliding. Radial thrust bearings, thrust ball bearings for high speed rotation.
5. For the ferrule, keep the correct position of the rolling element. Thrust ball bearings, thrust spherical roller bearings, when used in the horizontal axis.
Second, TIMKEN bearing preload method:
1. In order to carry out the preload, the method of adjusting the combined bearing of the difference in width or axial clearance beforehand is used.
2. Use an oversized gasket and shim to give the bearing a preload.
3. Fasten the screw that can adjust the axial direction clearance and the method after the nut. In this case, in order to obtain an appropriate preload amount, the TIMKEN imported bearing should be adjusted while measuring the starting friction torque.
The so-called constant pressure preload is a method in which a coil spring or a disc spring is used to give a proper load to the bearing. In use, the relative position of the bearing, even if there is a change, the method of preloading.
In the use of TIMKEN bearings, the relative load position can be kept constant even if there is a change in the relative position.
The preload line diagram of the imported bearing after constant pressure preload, the rigidity of the preload spring is usually small compared with the rigidity of the bearing, so the displacement of the spring is about parallel with the horizontal axis.

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Process characteristics for judging the vibration of imported bearings and the temperature of imported bearings

Core Tips: 1. Vibration of imported bearings The vibration of imported bearings is very sensitive to the damage of imported bearings. For example, peeling, indentation, rust, cracks, wear, etc. will all be reflected in the vibration measurement of imported bearings.
First, the vibration of imported bearings
The vibration of the imported bearing is very sensitive to the damage of the imported bearing. For example, peeling, indentation, rust, crack, wear, etc. will be reflected in the vibration measurement of the imported bearing. Therefore, by using a special bearing vibration measuring device (frequency analyzer, etc.) The magnitude of the vibration is measured, and the specific situation of the abnormality cannot be inferred by the frequency division. The measured values ​​vary depending on the conditions of use of the bearing or the mounting position of the sensor. Therefore, it is necessary to analyze and compare the measured values ​​of each machine in advance to determine the judgment standard.
Second, the temperature of the imported bearings
The temperature of the imported bearing is generally estimated by the temperature outside the bearing. If the oil hole can directly measure the temperature of the outer ring of the imported bearing, it is more suitable.
Usually, the temperature of the imported bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of the imported bearings varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the temperature of the imported bearings will rise sharply, and abnormal high temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.
The thermal sensor can be used to monitor the working temperature of the imported bearing at any time, and automatically alarm or stop the occurrence of the burning shaft accident when the temperature exceeds the specified value.
The use of high temperatures often indicates that the bearing is in an abnormal condition. High temperatures are also detrimental to the lubricants of imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. Long-term continuous rotation of the bearing at temperatures above 125 °C will reduce bearing life. Causes of high temperature imported bearings include: insufficient lubrication or excessive lubrication, lubricants. Containing impurities, excessive load, loss of imported bearings, insufficient clearance, and high friction caused by oil seals.
Therefore, it is necessary to continuously monitor the temperature of the imported bearings, whether it is measuring the bearing itself or other important parts. If the operating conditions are the same, any temperature change can indicate that a fault has occurred.
The periodic measurement of the temperature of the imported bearing can be carried out by means of a thermometer, such as a digital thermometer, which can accurately measure the temperature of the imported bearing and display it in °C or Fahrenheit.

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Judging the fault damage adjustment pre-tightening method of ntn angular contact ball bearing

From the peeling, indentation, rust, crack, wear and so on, it will be reflected in the vibration measurement of the bearing. The ntn bearing vibration is very sensitive to the damage of the bearing. Therefore, the angular contact ball bearing adopts a special bearing vibration measuring device ( The frequency analyzer can measure the magnitude of the vibration, and the specific situation of the abnormality cannot be inferred by the frequency division. Since the measured values ​​differ depending on the conditions of use of the bearing or the mounting position of the sensor, it is necessary to analyze and compare the measured values ​​of each machine in advance to determine the judgment standard.

Because the ntn bearing emits abnormal sounds and irregular sounds even if it is slightly peeled off, it can be distinguished by the sounder. The sounder is used to measure the size and sound quality of the angular contact ball bearings in operation. Check it to prevent it in advance.

If the oil hole can directly measure the bearing outer ring temperature, it is more suitable. In general, the temperature of the ntn bearing is generally estimated based on the temperature outside the bearing. If the lubrication and installation parts are suitable, the bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions. Usually, the temperature of the bearing rises slowly as the operation starts, and reaches a steady state after 1-2 hours. The normal temperature of an angular contact ball bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If necessary, use the thermal sensor to monitor the working temperature of the bearing at any time, and automatically alarm the household when the temperature exceeds the specified value or stop the burning shaft accident.

The assembly of the ntn bearing is the basic operation in the assembly and repair work of the fitter, and the adjustment and preloading of the clearance is an important part of the assembly work of the rolling bearing. Accurately grasping the process concept of clearance adjustment and pre-tightening, and correctly applying this process in assembly work is the guarantee of the quality of bearing assembly work.

The clearance of the ntn bearing refers to the maximum amount of movement of the other ferrule in the radial or axial direction when one ferrule is fixed, so the clearance is divided into radial clearance and axial clearance. When angular contact ball bearings are assembled, the clearance should not be too large or too small. If the clearance is too large, the number of rolling bodies that can bear the load at the same time is reduced, and the load of the single rolling element is increased, thereby reducing the rotation precision of the bearing and reducing the service life; if the clearance is too small, the frictional force is increased, and the generated heat is generated. Increased, increased wear and tear, can also reduce the service life of the bearing. Therefore, the bearings must be tightly controlled and adjusted during assembly.

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The importance of using deep groove ball bearing grease for stability

1, anti-rust performance

The rust preventive agent is preferably insoluble in water, has good adhesion, and can form an oil film on the surface of the steel.

2, mechanical stability

If the mechanical stability of the grease is insufficient, during the operation, the structure of the soap of the grease will mechanically disintegrate, causing the grease to be destroyed, thereby losing the lubricating effect.

3, oil seal

Oil seals are necessary to protect deep groove ball bearings and lubricants from external contamination. During the operation of TIMKEN bearings, no matter whether debris or moisture can penetrate into TIMKEN bearings to prevent damage.

4, mixed grease

Do not mix incompatible greases. If two incompatible greases are mixed, the consistency will usually become soft. Finally, the TIMKEN bearing may be damaged due to the easy loss of grease.

5, the classification of oil

The consistency and lubricity of grease are affected by the operating temperature. TIMKEN bearings operating at a certain temperature must select greases with the correct consistency and good lubrication at the same temperature.

In general, the amount of grease filled in deep groove ball bearings always exceeds the actual required amount of direct participation in lubrication, in the cavity on the frame and in the bearing cover, and forms a contour on the periphery of the rolling element. During this process, the bearing temperature rises rapidly due to the resistance of the excess grease. Although most of the excess grease is squeezed out at the beginning of the run, the grease that is squeezed into the raceway attachment may still be carried by the rolling element into the raceway. In the early stages of the bearing, most of the grease is squeezed out of the raceway very quickly (less than a minute), and the build-up grease is discharged a small amount while circulating along with the bearing rotor. At this time, the bearing temperature continues to rise until the excess bearing grease is completely discharged, which can be called the running phase of the grease. According to the grease quality and filling amount in the TIMKEN bearing structure, this time may last for more than ten. Minutes, even hours.

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Analysis of the Influence of Grease Viscosity on IKO Rolling Mill Bearings

The measure of internal friction during material activity is called viscosity. In order to prevent the contact surface between moving parts, the bearing lubricant must have sufficient viscosity, and the viscosity value decreases with increasing temperature. Viscosity is an important physical and chemical performance index for evaluating the quality of IKO bearing lubricants. It is of great significance for production, transportation and use.

Viscosity is the main technical index of bearing lubricants, but the viscosity of IKO bearing lubricants should not be higher than the degree that affects the start of the engine. Most bearing lubricants are classified according to their viscosity, and the viscosity is the oil of various equipment. mostly according. The measurement of viscosity is divided into two categories: absolute viscosity and relative viscosity. Absolute viscosity is divided into dynamic viscosity and kinematic viscosity; relative viscosity has several expressions such as Enshi viscosity, Sai's viscosity and Rayleigh viscosity.

The use of excessively large rolling mill bearing lubricants will increase the wear of the machine. In practical applications, the selection of lubricants of suitable viscosity will ensure that the mechanical equipment works normally and reliably. Generally, for low-speed and high-load applications, oils with higher viscosity are selected to ensure sufficient oil film thickness and normal lubrication. For high-speed and low-load applications, oils with lower viscosity are selected to ensure the normal starting of mechanical equipment. The running torque, the lubricating oil of the engine is too large, the activity is slow, the upstream is slow, and the oil pressure is high, but the lubricating oil passes through a small amount, and cannot be added to the friction surface in time, and the friction generated under the condition of continuous operation is the smallest.

Because the rolling speed of the rolling mill bearing oil is slow, the number of passes through the bearing lubricating oil filter is small, and it is difficult to clean the worn metal chips, carbon particles and dust from the friction surface in time. In operation, because the viscosity of the lubricating oil is large, the friction between the friction surfaces of the parts increases, and in order to overcome the increased friction, the fuel is consumed more, and the output power of the engine is also reduced. IKO bearing lubricants have high viscosity, and the oil's cycle speed is slow. The cooling and heat dissipation effects are poor, which makes the engine overheat. The temperature rise is small so that an oil film can be formed between the moving parts at various operating temperatures.

Therefore, do not use excessively strong engine oil, let alone think that the viscosity is as high as possible. Under the premise of ensuring lubrication, depending on the temperature range at the time of use, use a lubricant with a small viscosity as much as possible. However, for the engine that has been worn to a serious degree and the gap has been relatively large, a lubricant having a slightly higher viscosity can be appropriately selected.

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Standard method and lubrication maintenance for installing IKO railway bearings

Since IKO bearings are rust-proofed and packaged, do not open the package until installation. In addition, the anti-rust oil coated on the bearing has good lubricity. For general-purpose railway bearings or grease-filled bearings, it can be used without cleaning. However, for instrument bearings or bearings for high-speed rotation, the cleaning oil should be washed with a clean cleaning oil. The bearing is prone to rust and cannot be placed for a long time.

Clean the bearing and the casing to confirm the burrs left by scratches or machining. There must be no abrasive (SiC, Al2O3, etc.) sand or chips in the outer casing.

Secondly, check whether the size, shape and processing quality of the shaft and the casing are in accordance with the drawings.

The method of installing the IKO bearing depends on the matching, condition and structure of the railway bearing. Generally, since the shaft is mostly rotated, the inner ring needs an interference fit. Cylindrical bore bearings, press with multiple presses, or use hot charging methods. For taper holes, mount directly on the taper shaft or with a sleeve.

When installed in the outer casing, the general clearance fits a lot, and the outer ring has an interference amount, which is usually pressed by a press or a cold shrink fit method after cooling. When dry ice is used as the coolant and the shrinkage is installed, the moisture in the air will condense on the surface of the bearing. Therefore, appropriate rust prevention measures are required.

Just close the packaging bearing before installation. Generally smooth grease is smooth, not clean, and directly adds smooth grease. Smooth oil, generally not clean, but use instruments or high-speed bearings and clean with clean oil to remove the rust inhibitor applied to railway bearings. Remove the bearing, rust and rust inhibitor, we can't open it. In addition, it has been sealed up, the VTC grease bearing, not washed directly. The mounting method of the bearing differs depending on the bearing layout and the premise. Generally, more shafts are twisted, and the inner ring nuisance is suitable for the request.

The fit of the IKO bearing to the shaft is generally a transition fit. The fit between the race and the housing bore is generally a clearance fit. Therefore, the bearing is easier to install. The center shaft of the two-way thrust bearing should be fixed on the shaft to prevent relative The shaft rotates. The installation method of the railway bearing is generally the case where the shaft rotates. Therefore, the cooperation between the inner ring and the shaft is a win-win cooperation, and the cooperation between the outer ring of the bearing and the bearing chamber is a clearance fit.

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