The main shaft is one of the important components of the centrifugal fan. It connects the fan impeller and the motor bearing. Once worn or bent, it will affect the running accuracy of the centrifugal fan. Therefore, materials that are very wear-resistant and have sufficient hardness are usually used. What material is better for the high temperature centrifugal fan spindle?
The connection method of the centrifugal fan spindle
The function of the main shaft of the centrifugal fan is to support the rotation of the impeller and transmit the mechanical energy of the power device. The main shaft must have sufficient strength and rigidity to transmit mechanical energy and support the rotation of the impeller without vibration. There are two ways to connect the impeller and the main shaft:
1. The impeller with the hub structure is connected by the key on the shaft;
2. The impeller with flange structure is connected by high-strength hinged bolts, which can ensure the tight connection between the impeller and the main shaft under sufficient tightening torque, and the hinged bolts play the role of connection and positioning.
Both of these connection methods are used in double-support centrifugal fans. Cantilever centrifugal fans all use impellers with hub structure and key connections.
Common Materials and Selection of Centrifugal Fan Spindles
The main shaft of large centrifugal fans is mostly made of high-strength alloy steel forging and finishing. The fan will even use 304 stainless steel, but the centrifugal fan uses different spindle materials according to the working temperature:
1. Light-load centrifugal fans with working temperature ≤ 300°C are generally made of 45 steel;
2. For heavy-duty centrifugal fans with working temperature ≤300℃, 40Cr is used as the load shaft to improve the fatigue resistance;
3. For centrifugal fans in high temperature working environment, when the working temperature is 300℃≤t≤500℃, the main shaft material is generally 35CrMo or 42CrMo.
Assembly principle of centrifugal fan spindle
1. When the main shaft of the centrifugal fan is assembled, there should be no cracks, wear marks and damages on the main shaft and the journal. If there are wear marks and damage, it should be repaired with a group file without affecting the performance of the centrifugal fan equipment. Then polish and lubricate with oil-soaked emery cloth or whetstone.
2. When the main shaft and the bearing bush of the centrifugal fan are assembled, the top clearance is 0.015~0.002 of the journal diameter, and the side clearance is 1/2~2/3 of the top clearance; the contact point between the bearing bush and the journal is 12~18 points /25×25mm²; the radial displacement between the main shaft of the centrifugal fan and the motor shaft should not be treated as 0.05mm, and the levelness should be 0.2mm/m.
3. Before assembling the main shaft and the coupling of the centrifugal fan, all protective products on the main shaft assembly bearing and coupling parts should be removed and kept clean to ensure that there is no damage. Strict cleanliness must be maintained during bearing and spindle assembly, and the entire bearing should remain in its original packaging until the bearing is installed on the shaft.