Mechanical equipment will have different degrees of parts wear during long-term use. The impeller is one of the important parts of the centrifugal fan, and the wear is also relatively serious. The wear of the impeller will directly lead to the decline in the ventilation effect of the centrifugal fan. Prevention of specific reasons can make the centrifugal fan work better.
1) Causes of centrifugal fan impeller wear
1. Abrasive wear
In a centrifugal fan, solid particles move relative to the surface of the impeller at a certain speed, which will cause abrasive wear. The surface of the impeller is actually a kind of uneven contact surface for solid particles. Due to the filing effect under relative motion or the grinding effect of solid particles dispersed between the interfaces, the wear of the impeller will occur, and the wear of the impeller more common.
2. Adsorption wear
Under normal circumstances, when other operating conditions are the same, even if the machining accuracy level and cleanliness of the machining surface of the centrifugal fan impeller are improved, the degree of wear will not be reduced. On the contrary, the molecular adsorption will be obvious due to the close interface, resulting in a large amount of particle adsorption. On the surface of the impeller, the wear of the impeller interface is aggravated.
3. Fatigue wear
Due to the surface fatigue stress (or temperature or impact), the impeller surface of the centrifugal fan is cracked or scales fall off, which is called fatigue wear. Judging from the damaged impellers in the past, the wear conditions and parts of various forms of impellers are not the same, but they are basically local wear, and the wear parts are mainly on the working surface of the blade and near the back plate.
In addition to the above three causes of centrifugal fan impeller wear, there is also a case of surface scratches caused by solid particles in the air directly scouring the surface of the impeller, also known as scouring wear. After observing and determining the specific reasons, the general method to prevent impeller wear is to carry out surface treatment and improve the structure of the impeller blades, or directly install an air filtration system at the air inlet of the fan to prevent solid particles from entering the centrifugal fan.
2)Methods to prevent impeller wear of centrifugal fan
1. Surface treatment of the impeller
It is mainly to carry out carburizing, plasma surfacing, cemented carbide spraying, surface pasting of ceramic sheets and other treatments on the surface of centrifugal fan impeller blades. These methods are also commonly used methods, and their common advantage is that the hardness of the blade surface is improved, and the wear resistance of the impeller is improved to a certain extent, but each method has its own disadvantages:
(1) Carburizing: In the actual carburizing process, the position and thickness of the carburizing layer are determined by the thickness, wear and carburizing process of the blade.
(2) Plasma surfacing: The blade deforms greatly during the surfacing process, and repeated welding will cause cracks on the surface of the blade, which are prone to cracks and dents.
(3) Carbide spraying: It is difficult to determine the coating thickness when spraying.
(4) Ceramic sheets pasted on the surface: The effect of bonding ceramic sheets is better, but the price is expensive.
2. Spraying on the impeller surface
Spray the wear-resistant coating on the surface of the centrifugal fan impeller blades. This method is simple to operate and has a low single cost, but the disadvantage is also very obvious, that is, the wear is fast, and usually it will be sprayed again in about 3 to 5 months. This leads to frequent disassembly of the centrifugal fan, which can easily lead to poor sealing of the fan and other failures.
3. Improved blade structure
Improving the structure of the centrifugal fan impeller blade can reduce the wear of the impeller to a certain extent. Generally, the working surface of the blade is processed into a zigzag shape, and the hollow blade is changed into a solid blade, or wear-resistant blocks are welded on the blade. However, this method has higher requirements on the technical level of the improvement personnel.
4. Install the filter device
Installing a filter device at the air inlet of the centrifugal fan can effectively reduce the wear of the impeller. A commonly used method is to install wear-resistant cascades, which can allow solid particles to enter the fan and flow to the rear blade disc and blade root, so that concentrated wear becomes uniform wear, thereby improving the wear resistance of the impeller.