Bearing journal wear: sharing a method for on-site repair

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I. On-site repair of wear on the spindle journal of the JY002 type dryer 1. Fault symptoms and cause analysis: The equipment malfunction is caused by damage to the bearing at the solid short shaft at the input end, with irregular wear on the spindle journal amounting to approximately 3–6 mm. The reason is that the inner ring of the bearing rubbed dry against the spindle for a long time, until the inner ring broke and got stuck on the shaft. Opening the upper cover of the bearing housing, the bearing is shiny with no residue of lubricant, indicating a lack of oil. The oil filling port on the upper bearing cover is located in the center of the outer ring of the bearing; there are no oil channels leading to either side inside. Once the grease enters through the filling port, it can only flow into the bearing via the oil channels and holes provided in the bearing itself. This type of oil filling port can only be used with bearings that have lubrication grooves and oil holes in the centered position of the outer ring. 2. On-site repair construction process (using polymer composite materials): 1) Clean the surface to be repaired and the reference surface, removing oils, iron shavings, and other contaminants using alcohol or other organic solvents to reveal the true color of the equipment material. Ensure molecular-level adhesion to the repair materials. 2) Prepare the composite material Fosil Blue 2211F and apply it to the worn areas that need repair. When applying, it should be done evenly and densely, without any pores visible to the eye. After application, the diameter at the smallest area is about 4 mm larger than the standard diameter. 3) Machine the mold based on the reference surfaces of the shaft shoulders before and after the bearing position. Immediately after applying the material, install the clamping mold; the excess material is extruded through the discharge port. Once it has cured, open the mold to complete the repair and shaping process. The mold for repairing the worn areas of the bearing is shown in Figure 2. 4) After the repair is completed. The composite material coated with the wear-resistant layer can be left to cure naturally for 24 hours (baking can shorten the curing time), after which subsequent components such as bearings and sprockets can be installed. 5) Maintenance completed; trial operation and feeding started. It took 2 days to carry out the on-site repair of the worn area this time. 3. On-site operation diagram. II. On-site repair of wear on the journal of the coal crusher’s drive shaft. 1. Equipment parameters and condition of damage: Equipment name: Coal crusher. Damaged area: Wear on the diameter of the drive shaft (at the hydraulic coupling area). Shaft diameter: φ180 mm; Shaft width: 250 mm. Degree of wear: Up to 0.6 mm. Motor power: 990 Kw. Equipment rotation speed: 744 r/min. 2. On-site repair using polymer composite materials. Given the uneven wear on the shaft diameter, and considering that there is no wear at both ends of the keyway, the keyway area was adjusted to the topmost position. The undamaged areas were used as reference surfaces, and the diameter of the hydraulic coupling was utilized as a “mold” for restoring the proper dimensions in order to carry out the repair. Brief description of the implementation steps: 1) Carry out all preparations prior to assembly, including determining the fit between keys and keyways, fixing the dimensions for shaft journal fits, and preparing installation tools (hydraulic equipment and impact tools, etc.) ； 2) Remove the grease from the worn areas at the shaft ends using an oxy-acetylene flame; grind them with a angle grinder and sandpaper to reveal the original metal color, and clean them thoroughly with anhydrous ethanol ； 3) Mix an appropriate amount of the material and apply it evenly to the surface of the journal. Ensure that the worn areas are filled and repaired, then install the hydraulic coupler with the mold release agent applied to its shaft hole in place. On-site repair is ensured through the following steps: by using the reference surface (the areas at both ends of the keyway that are not worn) as a guide for positioning and installation, thereby ensuring the concentricity and parallelism after repair ； Rely on the bore diameter of the hydraulic coupler, to which a release agent is applied (to prevent sticking and facilitate subsequent maintenance), in order to restore the worn dimensions and ensure an optimal mating surface ； Reliance is placed on the material’s inherent properties such as compressive strength, bending resistance, ductility, and temperature resistance to ensure the performance of the repair. Repair diagram: This technology employs different repair methods depending on the degree of wear, as shown in the figure below. III. Summary of repair methods: The total costs associated with traditional maintenance methods, including labor costs, equipment transportation fees, and machining costs, are higher than those of on-site repairs; moreover, such methods are greatly limited by the space available at the site. The problems with traditional repair equipment cannot be resolved quickly and effectively on-site; significant time is wasted during the disassembly and installation processes. Common repair methods such as welding, plating, and spraying require more time compared to using polymer-based repair materials for on-site repairs. Using the polymer composite 2211F for on-site repair saves time in the three stages of demolition, repair, and installation. The principle involves utilizing the intermolecular forces resulting from the penetration of polymer molecules in the composite material to achieve excellent adhesion to the component being repaired; the physical properties of this material enable it to withstand various combined forces during the operation of the equipment.