While a machine is running it may be heating up and cooling down or operating at an elevated temperature. When this happens, there can actually be some relative movement between the shafts that had not been considered previously. The reason this is important is that not all coupling solutions are capable of axial compliance, and are considered axially rigid. The risk in this situation is the possibility of putting a large axial load onto the bearings of the motor. The same motor loading can be true with thrust loads.
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In a motion control system, there can be loading of the motor bearing if a solid coupling is used and transmits axial loads to the motor before engaging thrust bearings.
In the power transmission field, there are many different types of couplings that can be used in order to transfer power from the gear side to the machine. Taking into consideration that each specific application has its own features, it is extremely important to analyse and check what characteristics should our coupling have, to ensure a long-life cycle and a successful performance of our machinery.
We should take into account the following factors in the coupling selection process:
It is important to analyse the area, the temperature where the coupling is going to be exposed, and also if the device is going to be in a corrosive environment or not.
The space might be an issue when placing the coupling. In some applications there is a limited or a difficult access to locate the coupling. Therefore, this is also another key aspect to take into consideration for the coupling selection.
The type of shafts should be checked, as well as the diameter and the length.
As an example; considering the access, space required, and the shaft types, we have to analyse what size would apply best to our installation from our range of products.
The operator should check what types of misalignments should be corrected; parallel, torsional, axial, angular or lateral.
The main target consists on understanding what kind of performance we want to have with our coupling; high torque, high speed, repeatability or high level of flexibility and cushioning.
Decide which type of coupling will be most appropriate depending on the above aspects.
In order to determine the type of coupling to be used the following formula should be applied:
M = N hp/ n. . K
M = N kW/ n. . k
M = Nominal torque
N = Driving-motor power (CV or KW)
n = Minimum speed of the connected axles (rpm)
If you want to learn more, please visit our website Parallel Shaft Gear Reducer.
k = Multiplying co-efficient
The value obtained on applying the formula should be less or equal than the indicated in the tables of sizes and powers that refer to the corresponding coupling in the column nominal torque.
k = Multiplying co-efficientElectric motorNotes:
The values indicated in the above table are by no means applicable to every case. If, for example, one of the machines to be coupled displays such a degree of irregularity that it is judged necessary to carry-out technical investigations of the oscillations, then it is recommended to proceed to the selection of the multiplying co-efficient using the enclosed questionnaire.
K-coefficient calculation guidance for different groups of machines.
The elevator bucket is driven by a motor of 16 kW; n=1.450 rpm., by means of a reducer whose outlet axle rotates at a speed of n= 180 rpm. The motor and reducer are protected by a UNE-FLEX flexible axle coupling.
1. COUPLING BETWEEN MOTOR AND REDUCER
N = 16 kW
n = rpm
M = NKw/n. . k
Elevator buckets figure in group 2 of the classification. Under variable load machinery. The multiplying co-efficient k = 1,5 figures in the k value table under heading 2 and in the classification of machines driven by electric motor.
M = 16/ x x 1.5 = 158.07 Nm
Then, according to the power table. the appropriate coupling for a torque of 158 Nm. is model M-5.
2. COUPLING BETWEEN REDUCER AND ELEVATOR, BUCKET MECHANISM
N = 16 kW
n = 180 rpm
M = NKw/n. . k
M = 16/180 x x 1.5 = Nm
Then, according to the power table, the appropriate coupling for a torque of Nm is the model M-9.
Note: to carry out the correct selection of a coupling, an indication of power and speed is generally sufficient. However, its better to have the following information as well:
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