Writer: Eric Bearing Limited
The secondary causes of bearing marks appearing in the process of installation are: NSK bearings are skewed in the inner ring and outer ring during assembly and assembly; or perhaps the emergent charge in the process of installation and assembly sags the load, which eventually forms bearing emergent scars.
When the bearing is being installed, it must be stopped according to the work specification. If there are many achievements, if the form or method of the installation is not appropriate, it will form a linear scar on the raceway surface and the bone surface of the NSK bearing. The device of deep groove ball bearing indirectly reflects the precision, life and function of the bearing in use.
Although the bearing quality and other aspects are relatively good, rolling bearings are precision components, and their use must be carried out accordingly. No matter how high-performance bearings are used, if not used properly, the expected high performance will not be obtained. Eric Bearing Ltd have rich stock for NSK 6912DDU , if interested , pls kindly contact us .
There are the following items about the use of NSK bearings:
1.Keep the bearing and its surroundings clean.
Even small dust that is invisible to the eyes can have a bad effect on NSK bearings. Therefore, keep the surrounding clean, so that dust will not invade the bearing.
2.Use with care.
When the bearing is given a strong impact during use, it will cause scars and indentations, which will cause the accident. In severe cases, cracks and breaks may occur, so care must be taken.
3.Use appropriate operating tools.
Avoid using existing tools instead, you must use appropriate tools.
4.Pay attention to the corrosion of bearings.
In general, in order to control the noise impact of NSK bearings, countermeasures must be taken against the root causes of these noises in order to receive the remedy effect.
The main ways are:
(1)Select low-noise cylindrical roller bearings;
(2)Avoid resonance with the host, avoid resonance-sensitive speed;
(3)Try to eliminate noise from the application of cylindrical roller bearings;
(4)When other methods are ineffective, take additional measures for sound insulation and noise reduction.
When the temperature of the NSK bearing rises, first determine whether it is malfunctioning. If it does rise, it should be treated as follows:
Check the cooling water pressure, water flow and piping system are normal. If the water pressure is low, it may be that the filter is clogged. If it cannot be processed in time, it can be stopped for processing. When it is confirmed that it can work, it can be put into use again.
The oil pressure of the governor should be checked. If the oil pressure is low, the cooling water hydraulic valve may be closed.
Check whether there is any abnormal sound in NSK bearings and whether the swing of cylindrical roller bearings is abnormal.
Take an oil sample and observe whether the oil color has changed, and conduct a test to see if it deteriorates. If deterioration is confirmed, it should be stopped and replaced with new oil.
Check whether the oil level of the oil standard is normal. If it is abnormal, check whether the oil drain valve of the oil tank is tightly closed. If it is tightly closed, oil should be refilled. If the sealant is leaking oil, it should be shut down for treatment.
NSK bearing parts processing cooling technology
In the heat treatment process, the repaired parts must be normalized, and the structural parts that require mechanical performance indexes must be normalized and tempered to meet the mechanical performance requirements. Medium and high alloy steel and large forgings must be tempered after high temperature to eliminate internal stress generated during normalizing.
Some alloy steels produce a part of martensite transformation during forging, forming a hard structure. In order to eliminate such undesirable tissues, when normalizing is adopted, the temperature is higher than the normal normalizing temperature by about 20°C and the heat is kept warm for normalizing.
NSK bearing parts have high requirements, and there are bound to be many production processes. General bearing production requires 20 to 40 procedures, more than 70 procedures.
The working surfaces of bearing parts are all rotating forming surfaces, which are suitable for processing by forming method. For example, the forging, rolling and turning of the ferrule raceway are processed with forming tools or anti-profile plates.
Most surfaces of NSK bearing parts have to be ground, and the size and geometric accuracy of the grinding are in μM. Especially the precision of the raceway and rolling elements of the ring is higher, which requires super-finishing or grinding.
1)Annealing and cooling method: When steel is annealed, it is generally cooled with the furnace to below 600～550℃ and then air-cooled.
2)Normalizing cooling method: When steel is normalizing, it is generally cooled in air.
3) Quenching and cooling method: when the steel is quenched, the cooling rate of the steel in the most unstable range of supercooled austenite (650 ~ 550 ℃) should be greater than the critical cooling rate, so as to ensure that the workpiece does not transform into a pearlite structure; The cooling rate near the Ms point should be as low as possible, so as to reduce the quenching internal stress and reduce the deformation and cracking of the workpiece.
Therefore, when quenching, in addition to choosing a suitable quenching cooling medium, the quenching method should also be improved. For simple-shaped workpieces, a simple single-liquid quenching method is often used, such as carbon steel with water or brine liquid as the cooling medium, and alloy steel with oil as the cooling medium.
4)Tempering cooling method: carbon steel is generally cooled in air when tempered.
The normalizing process is a heat treatment process that heats the steel parts to 30 to 50°C above Ac3 (or Acm) and keeps them for an appropriate time and then cools in still air. Normalizing the steel to 100 to 150°C above Ac3 is called high-temperature normalizing.
The main purpose of normalizing low-carbon steel castings and forgings is to refine the structure. Compared with annealing, the pearlite layer is finer and the ferrite grains are finer after normalizing, so the strength and hardness are higher.
Due to the low hardness of the annealed steel after annealing, the phenomenon of sticking to the knife occurs during cutting, and the cutting performance is poor. The hardness can be improved by normalizing, which can improve the cutting performance. Some medium-carbon structural steel parts can be replaced by normalizing to simplify the heat treatment Craftsmanship.