The main causes of corrosion are as follows:
1. In the process of producing bearings, some enterprises did not strictly follow the requirements of cleaning and rust prevention Analysis procedures and oil seal rust prevention packaging to carry out rust prevention treatment on the bearing parts in the processing process and the finished bearing products after assembly.
If the turnover time of the ferrule is too long in the turnover process, the Analysis outer circle of the outer ring contacts corrosive liquid or gas, etc.
2. The quality of antirust lubricating oil, cleaning kerosene and other Analysis products used by some enterprises in production can not meet the requirements of process and technology regulations.
3. As the price of bearing steel falls again and again, the material of Analysis bearing steel gradually declines. For example, the content of non-metallic impurities in steel is high (the increase of sulfur content in steel reduces the corrosion resistance of the material itself), metallographic structure deviation, etc.
At present, the sources of bearing Analysis steel used by production enterprises are miscellaneous, and the steel quality is fish dragon mixed beads.
4. The environmental conditions of some enterprises are poor, the content of harmful substances in the air is high, and the turnover site is too small to carry out effective antirust treatment. In addition, the hot weather and the violation of rust prevention regulations by production workers also exist.
5. The bearing packaging materials such as antirust paper, nylon paper (bag) and plastic cylinder of some enterprises do not meet the Analysis requirements of antirust packaging of rolling bearing oil seal, which is also one of the factors causing corrosion.
6. The turning allowance and grinding allowance of bearing rings in some enterprises are too small, and the Analysis oxide scale and decarburization layer on the outer circle cannot be completely removed is also one of the reasons.
When installing the bearing, when the inner diameter of the bearing is greater than 70mm or the fit interference is large, the heating method is generally used to expand the bearing hole. In this way, the installation will save labor and time, and avoid the damage of the bearing caused by excessive force.
At this time, the heating temperature needs to be controlled. Generally, the bearing should be heated to 80 ℃ and 100 ℃ is enough. If the temperature exceeds 120 ℃, the bearing may be Analysis tempered, which will reduce the hardness and accuracy of the ferrule.
1、 Common methods of bearing heating include:
1. Bearing heating – electric heating plate heating method:
As long as the bearing is placed on the electric heating plate with a temperature of 100 ℃ for a few Analysis minutes, this method is simple and convenient. If it is turned over several times, the bearing can bear heat evenly, and the efficiency is also high. This method can be used to heat both large and small bearings.
2. Bearing heating electric furnace heating method:
The bearing is placed in a closed automatic temperature control electric furnace for heating. This method has the advantages of uniform heating, accurate temperature control and fast heating. It is suitable for a batch of occasions where many bearings are heated.
3. Bearing heating induction heating method:
This method can quickly, reliably and cleanly heat the bearing to the required temperature by using the induction heater.
This method is especially suitable for those occasions where the inner ring is tightly matched. Also, because only the inner ring is heated and the outer ring is heated very little, it can be easily installed on the shaft and into the seat hole.
This method uses 50W electric lamp bulb to heat the bearing, which can ensure that the heating temperature is about 100 ℃. The smaller bearing can be directly placed on the bulb, and the larger bearing can be placed in the conical cover of the bulb.
The conical cover can prevent the heat loss of the bulb and make the heating very uniform. The conical cover can also be adjusted up and down, which can be adapted to heating bearings of different sizes within a certain range.
If the far-infrared bulb is used, it should be noted that the direction of the bulb should be downward to avoid infrared rays from hurting people’s eyes. This kind of light bulb can save energy.
The heating method of bulbs is applicable to the occasions where the number is small and the bearings are not often heated. Usually, the bulbs can also be used for lighting. In addition, no other equipment is required.
5. Bearing heating – oil tank heating method:
This method is a widely used traditional heating method. A metal mesh is set at the place 50-70mm from the bottom of the oil tank, the bearing is placed on the mesh, and the large bearing is lifted with a hook.
The bearing is not suitable to be placed directly at the groove bottom to prevent the local heating temperature of the bearing contacting the groove bottom from being too high, or the dirt precipitated at the groove bottom from entering the bearing.
The key points of oil tank heating method are as follows: non corrosive mineral oil with good thermal stability should be used, especially transformer oil. The oil and container should be kept clean.
The capacity of the oil groove shall be determined by the size and oil quantity of the heated bearing. If the container is too small, the oil temperature will drop quickly as soon as the bearing is put into continuous operation, and the effect will be bad.