Repair of piston compressor crankshafts

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Repair of piston compressor cranks: When the crank is severely worn, has a high degree of ellipticity, which causes increased noise or bearing wear, it is necessary to repair the crank. The following introduces several repair methods for crankshafts and compares them. 1 Simple maintenance of the crankshaft: Chemical production is highly continuous, and sometimes simple maintenance methods are employed to keep production going. First, use a file to smooth out the protrusions that form at the curved joints, then sand them repeatedly with long-grit sandpaper until the surface is smooth, using tiles of similar thickness. Its disadvantages are that the elbow still has ellipticity, the surface finish is not high, and its service life is short. 2. Grinding of the shaft diameter: Use a crankshaft grinder to eliminate the ellipticity of the crank arms, and then fit corresponding thickened bearings. Its drawback is that, for safety reasons, there are certain limitations on the degree of refinement achievable using a crank grinder. When too much grinding occurs, the strength and wear resistance of the crankshaft decrease significantly, resulting in a short service life. There are also many types of thickened tiles, which makes management difficult. 3 Thermal spraying repair method: First, use a lathe to round the crankshaft diameter, then heat it to a certain temperature using an acetylene flame. Special spraying nozzles are used to apply the hot metal particles evenly onto the surface of the shaft diameter multiple times. After cooling, the crankshaft is ground to the standard dimensions using a crankshaft grinder. Cranks repaired using thermal spraying can use standard bearings, which facilitates management. However, it also has the following drawback: the coating layer cannot be too thick, otherwise it is prone to peeling off ； The sprayed layer has poor strength and wear resistance, is not impact-resistant, and generally can only be used for 1 to 2 years. 4. Reinforced iron plating repair method: Principle of reinforced iron plating – Before plating, the shaft diameter is rounded using a lathe, and the areas that do not require iron plating are covered up. During electroplating, by adjusting the parameters of the current, molecular bonding between the workpiece and the coating is achieved, resulting in lattice distortion; this helps to increase the strength and hardness of the coating. Finally, a crankshaft grinder is used to achieve the standard shaft diameter. Features of reinforced iron plating for crankshaft repair: high hardness, reaching HBC45–58; high adhesion strength; good wear resistance; and the plating layer can be relatively thick. Repairing crankshafts using reinforced iron plating offers the advantages of long service life, good results, and low costs, making it an ideal method for crankshaft repair.