The new technology applies dust-removing fan hard surface technology (1 Shanghai Shidongkou Metallurgical Equipment Repair Co., Ltd., Shanghai 2009422 Baosteel Group Pudong Steel Co., Ltd., Shanghai damage and corrosion caused the rotor balance dynamic failure, resulting in increased vibration of the unit can not operate normally. By improving the blade The design of the wear-resistant lining is made from the technical properties of the welding rod, the chemical composition of the surfacing metal, the hardness and metallographic phase of the surfacing metal, and the surfacing material is optimized. The new material and new technology are used to make the resistance. The service life of the fan of the lining plate is 1-2 times higher than the original.
Gu Jianxing was born in 1969. He graduated from Shanghai Metallurgy Higher Science in 1992. He is strictly engaged in the performance of metallurgical lock ectoPubli. It must be noted that when making wear-resistant plates, the pre-existing dust removal fan of Baosteel Group's Pugang Steelmaking Plant is used for the temperature of the soot collected by the converter soot from 70-90C, the dust particle size is < 06mm, and the fan speed is 720r'min. The air volume is 900,000m3. /h wind pressure 5 500Pa fan rotor weight 14t where the impeller weight 581t spindle weight 7 7835t The fan is manufactured by the drum factory, and the pre-protection measures for installing the composite wear plate are adopted for the easy wear of the blade during the production of the new product. However, after 2 to 3 months of normal operation, the vibration of the fan is intensifying. After the shutdown inspection, it is found that the original wear plate has been damaged due to the high-speed erosion of the soot. As a result, the dynamic balance of the fan rotor is invalid, resulting in increased vibration of the unit. normal operation.
To this end, it was decided to repair the wind turbine and cooperate with Shanghai Shidongkou Metallurgical Equipment Repair Co., Ltd.
1 Fan failure mechanism analysis After a period of operation of the fan, the vibration is intensified and the load is increased. The fundamental reason for the failure of the fan is that the fan blades are unevenly worn and corroded under the scour and corrosion of the flue gas and dust, making the dynamic balance. Invalid. The shape and structure of the fan blades determine that the flue gas and dust are not uniform to the erosion and corrosion of the blades, and the speed (life) of the fan failure depends on the reasonable configuration of the composite wear plates and the surfacing materials. Performance of use. The composite wear-resistant plate generally adopts 16Mn or 13MnV as the base body, and the surface is surfacing high-hardness wear-resistant material, that is, high-Cr cast iron, and the surfacing high-Cr cast iron is inevitably cracked, which is a normal phenomenon of releasing stress, and this kind of The crack is denser and shallower, which does not affect the welding direction. After the wear plate is mounted on the blade, the flow direction of the flue gas and the dust is perpendicular to the crack direction of the wear plate, so that the grinding groove phenomenon is not caused. Therefore, the service life of the high-Cr cast iron is varied, and it is necessary to pass the test, and it is preferable to have a high-Cr cast weld material with good wear resistance, high high-temperature hardness and high matrix bonding strength (not easy to peel off).
2Experimental research on surfacing materials In order to optimize the surfacing materials of the wear-resistant plates of the fan, we have tried three kinds of high-Ci cast iron welding rods SDK-SDK2 and SDK3 for experimental research.
21 welding rod process test The performance of the three kinds of welding rods are good, and there are no defects such as porosity and slag inclusion in the surfacing layer. Relatively speaking, the weld seam of SDK2 is slightly formed and splashed.
Chemical composition analysis of 22 surfacing metals The chemical composition of the three types of welding electrodes is shown in Table 1. Table 1 Chemical composition of surfacing metal Welding rods Other SDK2 welding rods contain the most alloying elements and contain some high temperature and strong resistance of other welding rods. Carbide forming elements. The content of C and Cr in SDK2 is also the highest. Obviously, it is advantageous for high temperature erosion wear of surfacing metal.
23 Hardness test of surfacing metal The room temperature, high temperature and section hardness of the three kinds of surfacing metals are shown in Table 2. The hardness of the 33 materials varies with temperature as shown.
Table 2 Room temperature and high temperature hardness of surfacing metal HV surfacing material temperature / c room temperature Note: The table below the line is the 3-point average, the corresponding HRC value in parentheses.
The correspondence between material organization and performance can be clearly seen.
It can be seen from the above chart that the hardness of SDK2 is significantly higher than that of the other two materials regardless of the surface or profile of the weld overlay layer and the normal temperature or high temperature. In particular, the higher the high temperature hardness, the more favorable the high temperature erosion wear, which is of great significance to improve the service life of spare parts.
24 Metallographic analysis The metallurgical structure of the surfacing metal of the three materials was observed under an optical microscope after being cut, polished, polished and etched by wire, as shown.
The microstructures of the three materials are carbides of various alloying elements distributed on the martensite-based matrix, such as chromium carbide, molybdenum carbide, vanadium carbide, and the like. The white blocks and ribbons in the figure are all carbides.
By comparison, the carbides of SDK2 are the finest and the distribution density is also the highest. Compared to SDK 2, the carbide particles are slightly larger and the distribution is slightly thinner. Although the photo of SDK1 is magnified 500 times, if it is reduced to the original 2 woven, it is quite magnified 200 times.) Obviously, its carbide particles are much larger than SDK2. Through metallographic analysis, through a series of experimental studies, it is confirmed that the three kinds of welding materials 2 have the best structure and the best performance, and are the materials of choice for the fan composite wear plate.
3 Preparation and installation of composite wear-resistant plates There are two methods for manufacturing wear-resistant layers on fan blades. One is to directly weld the wear-resistant layer on the blades. The advantage is that the construction is simple and convenient, but once the structure is deformed, it is difficult. Corrected and may affect the normal operation of the fan, and the number of repeated repairs is also reduced. The second is to make the wear-resistant lining and then compound with the blade. This method greatly reduces the amount of welding work on the blades. Therefore, the structural deformation can be effectively controlled, and a new liner can be replaced once the liner fails, so that the number of repeated repairs is increased, but the repair cycle is long and the workload is large. The comparison between the two is undoubtedly the latter is a reasonable choice.
Through the observation and analysis of the failed fan, not the entire blade is washed and worn, so it is not necessary to make all the composite wear-resistant 31 wear-resistant lining on the blade. The wear-resistant lining is composed of the substrate and the surfacing layer, and the substrate is made of 1MnV low alloy. Steel, thickness 8mm, surfacing material is SDK2 electrode. The specific production process is as follows: the sample is laid out according to the blade, and the sample is produced.
The plate is formed (the side substrate is planar).
Tooling production 1 is to control the structural deformation generated during surfacing, and the wear-resistant lining is surfacing on the pre-made master. That is, before the overlay welding, the formed substrate is firmly fixed to the tooling template whose shape is matched with the blade through the fixing hole. The tooling instructions determine the surfacing process parameters. The welding rod is SDK2(M); the welding current is 170 ~ 180A, the arc voltage is 24 plates, and the lower plate of the middle plate is close to 1 blade. It is also sharpened by ibrishhgHouse.Allrightsreserve (down to the 4th page. cnki.net 25V; welding current is reverse It is necessary to pay attention to controlling the crack direction during surfacing, so that the crack direction is perpendicular to the arc direction of the wear plate, because the direction of the airflow and dust is consistent with the arc direction of the blade. The thickness of the surfacing is 5~6mm, but The thickness of the end should be interfered by the BUS bus. Through the actual investigation on the spot, it is found that the speed of the cylinder moving back and forth is too fast. The round trip stroke takes about 6s to take into account the rolling speed of the unit and the width of the strip. We think that the speed is too fast, so the cylinder moving speed is external. Adjustment, so that the cylinder stroke is slowed down to 20s. In order to eliminate external interference, the CANBUS communication bus has also been re-shielded, and the benefits have been properly adjusted to improve the system's responsiveness. Through the above adjustment work, CPC correction The fluctuations have been greatly improved, the system is running stably, and the corrective response is rapid.
During the commissioning process, especially in the case of BA material, due to the bonding of the steel coils, the iron filings are particularly likely to accumulate on the light strip during unwinding, which weakens the compensation voltage and has a certain influence on the correction accuracy.
When doing such incoming materials, it is especially important for the cleaning of the probe and the optical tape. The detection voltage is periodically checked for the detection probe, and it is necessary to adjust the detector when the compensation voltage drift is large.
4 Conclusion At present, the DCR unit has entered the normal production stage, the CPC is running well, and the control accuracy meets the production needs. When the difference of the incoming material is less than 1mm and the total difference does not exceed 10mm, the correction accuracy is controlled within 1mm. The rectification is stable, the response is rapid, and the production needs are met, which can fully meet the requirements of the secondary cold rolling process. When making BA material, the incoming coil is prone to loosening. The normal deviation of CPC is extremely important for stable rolling and normal operation of production, which satisfies the production process requirements, helps to improve product quality, and embodies the correcting device. An important role in the rolling mill.
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