When the inner diameter of the bearing is greater than 70mm, or the fit interference is large, the heating method is used to expand the bearing hole, which saves labor and time for installation and avoids damage caused by excessive force.

At this time, the heating temperature needs to be controlled. Generally, the bearing is heated to 80°C, and the highest is 100°C. enough. Exceeding 120°C will cause tempering of the bearing, which will reduce the hardness and accuracy of the ferrule.

　　 1. Commonly used heating methods are:

　　1. Electric heating plate heating method:

　　 Put the bearing on the electric heating plate at a temperature of 100℃ for a few minutes. This method is the simplest, such as Turning over several times can make the bearing heat evenly, and the efficiency is also high. This method can be used for large and small bearings.

　　2. Electric furnace heating method:

　　 Put the bearing in a closed automatic temperature control electric furnace for heating, uniform heating, accurate temperature control, and fast heating. It is suitable for heating many bearings in a batch.

　　3. Induction heating method:

　　The induction heater can quickly, reliably and cleanly heat the bearing to the required temperature. This is especially suitable for the occasions where the inner ring is tightly fitted. The inner ring and the outer ring receive little heat, so that it can be easily installed on the shaft and easily installed in the seat hole.

　　4. Electric bulb heating method:

　　Using a 50W electric bulb to heat the bearing, the heating temperature can be guaranteed to be around 100℃. The smaller bearing can be placed directly on the bulb, and the larger bearing can be placed in the cone of the bulb. Inside the cover, the cone-shaped cover can prevent the bulb heat from dissipating and make the heating even. The conical cover can be adjusted up and down to adapt to heating bearings of different sizes within a certain range. If a far-infrared bulb is used, pay attention to the direction of the bulb downward, so as to avoid infrared rays that are harmful to human eyes. Imported pumps can save energy. The bulb heating method is suitable for a small quantity and not often needed; when the bearing is to be heated, the bulb can also be used for lighting at ordinary times, and no other equipment is required.

　　5. Oil tank heating method:

　　 This is a widely used traditional heating method. A metal mesh is set at the bottom of the oil groove 50～70mm, the bearing is placed on the net, and the large bearing needs to be lifted with a hook. The bearing should not be placed directly on the bottom of the groove to prevent the part of the bearing contacting the bottom of the groove from being overheated or the dirt deposited on the bottom of the groove entering the bearing. The main points of attention of the oil tank heating method are as follows. Non-corrosive mineral oil with good thermal stability should be used, preferably transformer oil. The oil and the container should be kept clean. The capacity of the oil tank should be determined by the size of the heated bearing and the amount of oil. If the container is too small, the temperature of the oil will drop quickly as soon as the bearing is put into the bearing during continuous operation, and the effect will not be good.

　　 Second, the main points of the heating installation method:

　　①The heating temperature should be controlled properly, the bearing will be damaged if the temperature is too high, and the expansion of the ring will be insufficient if the temperature is too low, and the effect is not significant. The thermal expansion of the inner diameter of the inner ring at a heating temperature of 80-1000°C is sufficient for bearings with general interference.

　　② Once the required heating temperature is reached, it must be installed as soon as possible to avoid cooling and installation difficulties.

　　③The bearing also shrinks in the width direction during cooling, so a certain pressure must be applied to press the inner ring to the shoulder during installation, and after cooling, use a very thin feeler gauge to test whether the inner ring is There is a gap between the end face and the shaft shoulder. In short, butterfly work requires skill, speed and accuracy.