SIZING AND SELECTION INDUSTRIAL DRIVE COUPLINGS ST
Symbols
| TAR | Disengagement torque of the coupling (Nm) |
| K | Service factor |
| Tmax | Maximum torque of the drive system (Nm) |
| TAN | Rated torque of the motor (Nm) |
| PDrive | Drive power (kW) |
| n | Drive speed (min-1) |
| ∝ | Angular acceleration |
| t | Acceleration time (s) 1/s² |
| JL | Moment of inertia of load (kgm2) |
| JA | Moment of inertia of drive (kgm2) |
| TAS | Peak motor torque (Nm) |
| S | Number of safety elements |
| F | Tangential force (kN) |
| r | Radius to element (m) |
| s | Spindle pitch (mm) |
| Fv | Feed force (N) |
| η | Spindle efficiency |
| d0 | Pitch diameter (mm) |
| Fv | Feed force (N) |
| CT | Torsional stiffness of coupling (Nm/rad) |
| JMasch. | Total load inertia (kgm2) (e.g. shaft + sprocket + chain + roller + 1/2 of coupling) |
| JMot. | Total driving inertia (kgm2) |
| fe | Resonant frequency of the two mass system (Hz) |
According to disengagement torque
Safety couplings are normally selected according to the required disengagement torque, which must be greater than the maximum torque required for start-up and operation.
Disengagement torque values are often determined from the drive data and are typically a multiple of the nominal torque at the operating drive speed (TAN). In addition to a start-up torque (TMAX), the following values are used as further safety factors, depending on the load conditions:
K = 1.3 uniform harmonious load
K = 1.5 non-uniform load
K = 1.8 heavy shock load
According to resonant frequency
The torsional natural frequency of the coupling must be significantly higher or lower than that of the equipment. For the mechanical substitution model the two mass system applies
Load factors by machine type
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EXCAVATORS CONSTRUCTION MACHINERY CHEMICAL INDUSTRY FEEDERS AND CONVEYORS |
BLOWERS AND FANS1 GENERATORS AND TRANSFORMERS RUBBER MACHINERY WOOD PROCESSING MACHINERY CRANES PLASTIC MACHINERY METALWORKING MACHINERY |
S presses PAPER MACHINERY PUMPs STONE AND CLAY MACHINES |
S rotary kilns TEXTILE MACHINERY COMPRESSORS METAL ROLLING MILLS LAUNDRY MACHINES WASTEWATER TREATMENT PLANTS |
According to torque
1. Calculate the drive torque TAN.
2. Base the coupling rated torque TKN on the drive torque TAN multiplied by the application factors.
Ratings chart
Maximum torque, speed and misalignment are related and can not exist at the same time.
Evaluation T/TKN and n / nmax
Compare plotted values for combined limits.
