Views:0 Author:Site Editor Publish Time: 2021-05-07 Origin:Site
Flexible couplings can fail as a result of human error, typically occurring during the design, installation, or maintenance of the item. Selection of an unsuitable design usually results in a flexible coupling being placed in service that is too small or is the wrong design for the application. Flexible coupling’s failure can also result from improper installation of the coupling itself. As failures mentioned above, how can we change flexible coupling?
What are the faults of flexible coupling?
How to change flexible coupling?
How to align flexible coupling?
With an increase in misalignment, surface contact area decreases, resulting in increased loading on flexible coupling components. This results in increased friction. This increased friction imposes a corresponding pre-load to the two shafts that are connected by the flexible coupling. This prevents the flexible coupling from moving axially, commonly called flexible coupling lock-up to compensate for misalignment.
Fretting occurs when two surfaces move in relation to one another. The loading and heat generated by friction causes metal to be removed, to be transferred, or to crack. Fretting is actually fatigue of metal surfaces. In gear and grid couplings flex members slide in relation to each other.
Wear is the major problem with lubricated flexible couplings. Most cases of wear can be traced to the lack of lubrication. Dirt in the lubricant can cause disaster. Overfilling with grease in a gear or grid coupling is a very common mistake and should be avoided because heat can build up in the flexible coupling or cause a hydraulic lock. After packing, check that the flexible coupling will move back and forth to ensure that the flexible coupling is not grease-bound.
In a disc flexible coupling, failures result from fatigue due to excessive flexure from greater than designed misalignment. If a disc coupling is installed such that the distance between two shafts is too much or less as compared to designed distance, it leads to axial misalignment. A disc coupling can be inspected for damage without its disassembly if discs are visible. It can be checked with a strobe light while it is in operation. Under a strobe light the discs can be seen flexing and moving and a damaged disc would show up.
In the process of disassembling the flexible coupling, the most difficult task is to remove the hub from the shaft. For the hub of the flexible coupling, a three-legged puller or a four-legged puller is generally used for disassembly. The selected puller should match the outer dimensions of the hub, and the right-angle hooks of each leg of the puller should be properly combined with the rear side of the hub, so that no slippage will occur when you apply force. This method is only used for disassembly of hubs with relatively small interference.
For hubs with relatively large interference, heating methods are often used, or at the same time with hydraulic jacks for disassembly. When heating, it should be slow with segmented heating to ensure insulation should be sufficient. Generally heating flexible coupling uses trolley furnace to dry. Low-carbon and low-alloy steel is directly quenched with salt water, and medium-carbon alloy structural steel is quenched with water and oil double liquid. It is safer to use the effective thickness to calculate the residence time in water. The new water-cooling medium is suitable for forgings with simple shapes, single materials and products. The flexible coupling should generally be equipped with a torsion angle limiter, and it may not be installed under special circumstances. When the flexible coupling is used, the relative offset of the two connected shafts should not be greater than the specified allowable compensation amount. There should be no bumps, cracks, lack of glue and other defects on the rubber surface of the flexible coupling. There should be no tearing off at the rubber and metal bonding. The film marks with a depth of more than 1.0mm, slight bumps and burrs should not be deeper than 1.5 air bubbles, rubber surface defects outside this range are allowed to be ground once. The rubber in the metal, the outer wheel surface and the metal hole should be clear and clean.
During the static torsion test of the rubber elastic ring of the flexible coupling, the rubber of the rubber elastic ring should not have any cracks and the phenomenon of rubber and metal ripping under the momentary high torque.
When assembling the flexible coupling, replace with new bolts, which must be consistent with the original bolt specifications. The bolts used for the new replacement of the high-speed equipment flexible coupling must also be weighed so that the new bolts have the same weight as the connecting bolts on the same set of flanges.
1. Fix the outer foot on the side of the flexible coupling. Move the inner foot until the eccentric line between the motor and the pump center is zero. In order to ensure that the machine does not move arbitrarily, after fixing the feet of one side of the machine, the other side should be supported by the top wire.
2. Fix the inner feet of the flexible coupling and move the outer feet to make the eccentricity of the two center lines zero.
3. After the above two methods are repeated several times, the flexible coupling can be in a good alignment state.
The alignment of hoisting flexible coupling is an important task. Although the principle of alignment is simple, it is very practical. The alignment methods often used on small pumps include single-meter method, double-meter method, and three-meter method. No matter which method, there is a common feature that the alignment in the horizontal plane is more error-prone than the vertical plane. It is repetitive, time-consuming, and the calculation is cumbersome.
Learn more something about flexible couplings can know the common faults of flexible couplings and how to change flexible couplings. If you want to buy good shaft couplings with reasonable price, FOSHAN HOUZHE TRANSMISSION EQUIPMENT CO., LTD. is your best choice. Whether from quality or price, or delivery time, we can help customers to open up a further and larger market. We have all types of different flexible couplings and if you have any questions, you can contact us or search us online.