Disassembly is the opposite process of assembly, and their purposes are different. The assembly process involves putting the coupling components together according to assembly requirements, ensuring that the coupling can transmit torque safely and reliably. Disassembly is generally performed due to equipment malfunction or the need for maintenance of the coupling itself, resulting in the dismantling of the coupling into its individual parts. The extent of disassembly usually depends on maintenance requirements; sometimes, it is only necessary to separate the connected shafts, while in other cases, the coupling needs to be completely disassembled, including removing the hubs from the shafts. There are many types of couplings with varying structures, so the disassembly processes differ as well. Here, we will primarily focus on some important considerations during the coupling disassembly process.
Before disassembling the coupling, it’s important to mark the positions where the various components of the coupling are aligned with each other. These marks serve as references for reassembly. For couplings used in high-speed machines, the connecting bolts are usually weighed and marked, and it’s crucial to ensure accurate marking to avoid confusion.
When disassembling a coupling, the typical approach is to start by removing the connecting bolts. Due to the accumulation of oil residues, corrosion products, and other deposits on the threaded surfaces, removing bolts can be challenging, especially for severely rusted bolts. Choosing the right tools is essential for the disassembly of connecting bolts. If the external hex or internal hex surfaces of the bolts are already damaged, disassembly becomes even more difficult. For bolts that are corroded or covered in oil residues, applying solvents (such as rust penetrants) to the connection between the bolt and nut is often helpful. This allows the solvent to penetrate the threads, making it easier to disassemble. If the bolt still cannot be removed, heating can be employed, with a temperature generally kept below 200°C. Heating increases the gap between the nut and bolt, facilitating the removal of rust deposits and making the disassembly process easier. If none of the above methods work, the last resort is to damage the bolt by cutting or drilling it out and replacing it with a new bolt during reassembly. The new bolt must match the specifications of the original bolt. For couplings used in high-speed equipment, the newly replaced bolts must also be weighed to ensure they have the same weight as the connecting bolts on the same flange.
The most challenging task during the disassembly of a coupling is removing the hub from the shaft. For key-connected hubs, a three-legged or four-legged puller is commonly used. The chosen puller should match the outer dimensions of the hub, and the right-angle hooks of the puller legs should fit securely against the rear surface of the hub, preventing slippage during application of force. This method is suitable for disassembling hubs with relatively small interference fits. For hubs with larger interference fits, heating is often used, sometimes in combination with a hydraulic jack for assistance.
Thoroughly cleaning, inspecting, and evaluating the quality of all coupling components is a crucial task after disassembly. Component evaluation involves comparing the current condition of each part’s dimensions, shape, and material properties after operation with the quality standards specified in the part’s design. This helps determine which parts can continue to be used, which parts can be repaired for further use, and which parts should be discarded and replaced.
Post time: Aug-23-2023