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 tempered, which will reduce the During Heating 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 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 During Heating 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 During Heating 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 During Heating easily installed on the shaft and into the seat hole.
4. Bearing heating – electric bulb heating method:
This method uses 50W electric lamp bulb to heat the bearing, which can During Heating 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 During Heating 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 During Heating 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 During Heating addition, no other equipment is required.
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 During Heating 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.
2、 Key points of bearing heating installation method:
1. The bearing heating temperature shall be well controlled. If the temperature is too high, the bearing may be damaged, and if the temperature is too low, the expansion of the ferrule may be insufficient, resulting in insignificant effect.
The amount of thermal expansion of the inner diameter of the inner ring obtained from the heating temperature of 80 to 100 ℃, which is very sufficient for bearings with general interference.
2. Once the required heating temperature is reached, the bearing shall be installed as soon as possible to avoid installation difficulties caused by bearing cooling, etc.
3. When the bearing cools, it will shrink in the width direction. Therefore, during installation, a certain pressure should be applied to compress the inner ring to the shoulder.
After the bearing cools, a very thin feeler gauge should be used to make a simple inspection. It also depends on whether there is a gap between the end face of the inner ring and the shaft shoulder, etc.
In a word, it is required to move skillfully, quickly and accurately during bearing installation.