About Shaft Couplings
A shaft coupling is a mechanical element that connects the travel shaft and driven shaft of a electric motor, etc., so as to transmit ability. Shaft couplings expose mechanical flexibility, featuring tolerance for shaft misalignment. Consequently, this coupling overall flexibility can reduce uneven put on on the bearing, products vibration, and additional mechanical troubles because of misalignment.
Shaft couplings can be found in a tiny type mainly for FA (factory automation) and a huge casting type used for large power transmission such as for example in wind and hydraulic electric power machinery.
In NBK, the former is called a coupling and the latter is named a shaft coupling. Here, we will discuss the shaft coupling.
Why Do We Need Shaft Couplings?
Even if the motor and workpiece are immediately connected and appropriately fixed, slight misalignment can occur over time because of improvements in temperature and changes over an extended period of time, causing vibration and damage.
Shaft couplings serve seeing that an important connect to minimize influence and vibration, allowing smooth rotation to be transmitted.
Flexible Flanged Shaft Couplings
Characteristics
These are the most used flexible shaft couplings in Japan that comply with JIS B 1452-1991 “Flexible flanged shaft couplings”.
A simple structure made of a flange and coupling bolts. Easy to set up.
The bushing between the flange and coupling bolts alleviates the consequences of torque fluctuation and impacts during startup and shutdown.
The bushing could be replaced by just removing the coupling bolt, enabling easy maintenance.
Permits lateral/angular misalignment, and reduces noises. Prevents the thrust load from simply being transmitted.
2 types are available, a cast iron FCL type and a carbon metal?FCLS type Flexible Shaft Couplings
Shaft Coupling Considerations
In picking couplings a designer initial must consider motion control varieties or power transmission types. Most motion control applications transmit comparatively low torques. Power transmission couplings, in contrast, are created to carry average to high torques. This decision will narrow coupling choice relatively. Torque transmission along with optimum permissible parallel and angular misalignment values are the dominant considerations. Many couplings will publish these values and with them to refine the search should produce deciding on a coupling style much easier. Optimum RPM is another vital attribute. Optimum axial misalignment could be a consideration aswell. Zero backlash is an essential consideration where responses is employed as in a action control system.
Some power transmission couplings are made to operate without lubricant, which may be a plus where maintenance is a concern or difficult to execute. Lubricated couplings quite often require covers to keep the grease in. Many couplings, including chain, equipment, Oldham, etc., can be found either while lubricated metal-on-metal types and as steel and plastic material hybrids where generally the coupling element is constructed of nylon or another plastic to remove the lubrication requirements. There exists a reduction in torque potential in these unlubricated varieties when compared to more conventional designs.
Important Attributes
Coupling Style
Almost all of the common styles have already been described above.
Maximum RPM
Most couplings have a limit on their maximum rotational swiftness. Couplings for high-acceleration turbines, compressors, boiler feed pumps, etc. generally require balanced patterns and/or balanced bolts/nuts allowing disassembly and reassembly without raising vibration during operation. High-speed couplings may also exhibit windage results in their guards, which can result in cooling concerns.
Max Transmitted Horsepower or perhaps Torque
Couplings are often rated by their maximum torque potential, a measurable quantity. Electrical power is normally a function of torque instances rpm, consequently when these ideals are stated it is normally at a specific rpm (5HP @ 100 rpm, for example). Torque values will be the additionally cited of the two.
Max Angular Misalignment
Among the shaft misalignment types, angular misalignment capacity is usually stated in degrees and represents the maximum angular offset the coupled shafts exhibit.
Max Parallel Misalignment
Parallel misalignment capacity is generally given in linear products of inches or millimeters and represents the utmost parallel offset the coupled shafts exhibit.
Max Axial Motion
Sometimes called axial misalignment, this attribute specifies the maximum permissible growth between the coupled shafts, granted generally in inches or perhaps millimeters, and can be caused by thermal effects.