Centrifugal fans are mainly composed of casing, impeller, and motor. The main function of the casing is to protect the fan and stabilize the rotation of the impeller. However, in some cases, the casing of the centrifugal fan will be deformed to a certain extent, although the short-term It has no effect on the operation of the fan, but if it is not dealt with in time, it will affect the wind pressure and operating efficiency of the fan. What about the deformation of the centrifugal fan casing?
1. Reasons for the deformation of the centrifugal fan casing
1. Force deformation
In the process of handling and installation of centrifugal fans, the casing may be deformed due to improper operation. This is because the casing of the fan industry generally uses a steel plate less than 6mm, which is thin and the plane part is large. The content part is mostly large space without support, and it is easy to be dented and deformed once it is bumped.
2. Thermal deformation
During the operation of the centrifugal fan, the rotor of the centrifugal fan will generate a certain amount of heat due to the high-speed rotation, and this heat will be transferred to the casing. In addition, some industries are not in continuous production, and the temperature of the casing will alternate between cold and heat, which will cause the machine to rotate. Part of the casing is deformed, and this phenomenon is more serious when the lubrication of the centrifugal fan rotor is insufficient.
3. Welding deformation
The casing of the centrifugal fan is originally relatively thin. During the initial production of blanking or stretching, a certain stress will be generated inside. The case of casing deformation, but not all centrifugal fan casings will have welding deformation, which is mainly related to the structural size, material, welding process, etc. of the casing.
2. The influence of the deformation of the centrifugal fan casing
1. Reduce fan efficiency: The inside of the centrifugal fan casing is an important gas passage area. Under the condition of a certain impeller size, the smaller this part of the space, the greater the inlet pressure of the fan, and the greater the amount of induced air. The smaller it is, the more likely it will not be able to meet production requirements.
2Causes operating failures:The deformation of the casing will directly affect the normal rotation of the fan impeller rotor. If the deformation exceeds the clearance, the operating load of the rotor will be increased. In the long run, it will not only cause abnormal running noise, but also It causes the deformation of the rotor bearing and causes the fan to vibrate.
It is not difficult to see that when the casing of the centrifugal fan is deformed, it will directly affect the use of the fan. As for the deformation of the casing of the centrifugal fan, it is generally corrected after the fan is stopped and the casing is removed. Several solutions are provided for your understanding only. If necessary, it is recommended that you contact the centrifugal fan manufacturer for corrective operations.
3. the solution to the deformation of the centrifugal fan casing
1. Mechanical correction method
The mechanical correction method is to use the mechanical impact force or pressure to promote the reverse deformation of the casing to achieve a normal appearance. It is divided into two types: hammering method and pressure method:
(1) Hammering method: Hammer the deformation area of the casing with a hammer to eliminate the deformation through the extension of the metal. This method is mostly used for welding deformation, but a little carelessness will damage the casing of the casing. Appearance quality, and labor-intensive.
(2) Pressure method: The pressure method mainly uses a jack. When the side plate of the casing is partially depressed, the depression can be lifted with a jack to achieve the purpose of correction.
2, flame correction method
The flame rectification method uses the plastic deformation of the metal produced by local heating, and then achieves the rectification of the casing by cooling and shrinking. The deformation of the centrifugal fan casing is also mostly used in this method, and the main heating pad is at the edge of the deformation. The heating range of this method is relatively large, which may increase the outer arch of the casing. Therefore, a perforated plate is generally used to press the centrifugal fan casing, and then the side plate is heated through small holes to improve the correction efficiency.
3. Combined correction method
The deformation of the centrifugal fan casing is mostly caused by thermal deformation and welding deformation. Among them, the deformation of the welding machine is more complicated. In many cases, it is difficult to achieve the purpose of correction by a single correction method. Therefore, a joint correction method is usually used, that is, the use of mechanical Correction and flame correction. When using this method, the correct selection of the mechanical correction part and the flame heating point and reasonable matching can quickly correct the thin and cool deformation of the centrifugal fan casing.
4.the common casing materials of centrifugal fans
Under normal circumstances, the casing of the centrifugal fan is made of carbon steel, and it is difficult to prevent the deformation. So there is another solution to the deformation of the casing of the centrifugal fan, which is to choose the casing material reasonably. Currently on the market There are various materials for the centrifugal fan casing, which needs to be selected according to the actual use environment and process.
1. Carbon steel: General centrifugal fans are made of carbon steel as the main material of the casing, because the market price of carbon steel is relatively cheap, and the processing procedures are relatively small, which is very easy. This kind of centrifugal fan with carbon steel as the main material of the casing is mainly used in the environment of normal temperature, no dust and not easy to be corroded.
2. FRP: FRP is also a common centrifugal fan casing material, mainly used for ventilation in a corrosive gas environment. FRP is made of glass fiber and resin glue, and its anti-corrosion properties are very good. Widely used in many chemical workshops.
3. Stainless steel: There are many grades of stainless steel used in the centrifugal fan casing, such as martensitic steel, ferritic steel, austenitic steel, etc. They are also very good in corrosion resistance and high temperature resistance. Although the price is slightly higher than the first two materials, the centrifugal fan with stainless steel casing has a longer service life in a high temperature and perishable environment.
4. Plastic: Although plastic is rare as the casing material of centrifugal fans, it does exist. This is because of the special anti-corrosion properties of plastic, and it has a relatively good performance in some anti-corrosion fans. The strength is lower than that of FRP, so it is hardly used on larger centrifugal fans.