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Highly flexible couplings ELPEX series

  • Информационные материалы

    Информационные материалы

    ELPEX couplings are highly torsionally flexible and free of torsional backlash. Because of their low torsional stiffness and damping capacity, ELPEX couplings are especially suitable for coupling machines with a very non uniform torque pattern. ELPEX couplings are also suitable for connecting machines with high shaft misalignment.

    Standard ELPEX coupling types are designed as shaft-shaft connections or flange-shaft connections. Application-related types can be implemented on request.

    Область применения

    The ELPEX coupling is available in 9 sizes with a nominal torque of between 1600 Nm and 90000 Nm. The coupling is suitable for ambient temperatures of between –40 °C and +80 °C.

    The ELPEX coupling is frequently used for high-quality drives which have to guarantee very long service life in harsh operating conditions. Examples of applications are mill drives in the cement industry, marine main and secondary drives or drives on large excavators powered by an electric motor or diesel engine.

    Дизайн

    Design and function

    The ELPEX coupling's transmission characteristic is determined essentially by the flexible rings. The flexible rings are manufactured from a natural rubber mixture with a multiply fabric lining. The flexible rings are split so that they can be changed without having to move the coupled machines.

    The flexible rings are fastened to the hub with a clamping ring and to the outer flange with a clamping ring, using pins and bolts.

    On the type EFG, the outer flange is designed with connection dimensions for connection to e.g. a diesel engine flywheel. On ENG types, the outer flange is fitted to a second hub part, which then enables the shaft-shaft connection.

    Materials:

     

    Type

     

    Cast iron

    Steel

    Hub part 1

    Grey cast iron
    EN-GJL-250

    Steel

    Hub part 2

    Steel

    Steel

    Retaining ring, outer ENG, ENGS

    Grey cast iron
    EN-GJL-250

    Steel

    Outer flange EFG, EFGS

    Grey cast iron
    EN-GJL-250

    Steel



    Flexible ring materials:

    Material/description

    Hardness

    Identification

    Ambient temperature

    Natural rubber

    70 ShoreA

    Size - 2

    –40 °C to +80 °C



    ELPEX coupling types

    Type

    Description

    ENG

    Coupling as shaft-shaft connection

    EFG

    Coupling as flange-shaft connection

    ENGS

    as ENG with fail-safe device

    EFGS

    as EFG with fail-safe device



    Types ENG/ENGS

    Types EFG/EFGS

    Further application-specific coupling types are available.
    Dimension sheets for and information on these are available on request. The following versions have already been implemented a number of times:

    • ELPEX coupling with brake drum, brake disk or flywheel mass
    • ELPEX coupling with axial backlash limiter
    • ELPEX coupling with adapter
    • ELPEX coupling in combination with a safety slip clutch
    • ELPEX coupling for engaging/disengaging during standstill
    • ELPEX coupling as part of a coupling combination

    Fail-safe device of ELPEX coupling

    Types ENGS and EFGS are provided with a fail-safe device. In normal operation the torsion angle of the flexible rings is smaller than the gap between the cams. In normal operation there is no metal-metal contact.

    If the flexible rings fail, cams transmit the torque from the inner part and outer part. These enable the coupling to be used in emergency mode for a short time. This option is frequently required e.g. in the case of marine drives.

    Fail-safe device

    Конфигурация

    The ELPEX coupling is especially suitable for rough operation. An application factor different from that in catalog section 3 is therefore sufficient for all applications. In the case of machines which excite torsional vibration, FLENDER urgently recommends carrying out a torsional vibration calculation or measuring the coupling load occurring in the drive.

    Coupling selection

    Coupling load in continuous operation

    The operating principles of the driving and driven machines are divided into categories and the application factor FB derived from these in accordance with DIN 3990-1.

    Application factor FB

    Torque characteristic of the driven machine

    Torque characteristic of the driving machine

    uniform with moderate shock loads

    non uniform

    very rough

    Electric motors, hydraulic motors, gas and water turbines

    1.0

    1.3

    1.4

    Internal combustion engines

    1.3

    1.4

    1.6



    Examples of torque characteristic in driven machines:

    • uniform with moderate shock loads: generators, fans, blowers
    • non uniform: reciprocating compressors, mixers,
      conveyor systems
    • very rough: crushers, excavators, presses, mills

    Temperature factor FT

    Temperature Ta on the coupling

    Coupling

    Elastomer material

    –40 °C to –30 °C

    –30 °C to +50 °C

    to 60 °C

    to 70 °C

    to 80 °C

    ELPEX

    NR

    1.1

    1.0

    1.25

    1.40

    1.60



    NR: Natural rubber mixture

    Select size with: TKN ≥ TN · FB · FT

    Coupling load at maximum and overload conditions

    The maximum torque is the highest load acting on the coupling in normal operation.
    Maximum torques at a frequency of up to 25 times an hour are permitted and must be lower than the maximum coupling torque. Examples of maximum torque conditions are: Starting operations, stopping operations or usual operating conditions with maximum load.

    TKmax ≥ Tmax · FT

    Overload torques are maximum loads which occur only in combination with special, infrequent operating conditions. Examples of overload torque conditions are: Motor short circuit, emergency stop or blocking because of component breakage. Overload torques at a frequency of once a month are permitted and must be lower than the maximum overload torque of the coupling. The overload condition may last only a short while, i.e. fractions of a second.

    TKOL ≥ TOL · FT

    Coupling load due to dynamic torque load

    Applying the frequency factor FF, the dynamic torque load must be lower than the coupling fatigue torque.

    Dynamic torque load
    TKW ≥ TW · FT · FF · 0.6 / (FB – 1.0)

    Frequency of the dynamic torque load
    ferr ≤10 Hz frequency factor FF = 1.0

    Frequency of the dynamic torque load
    ferr >10 Hz frequency factor FF = √(ferr / 10 Hz)

    Checking the maximum speed:

    The following must apply to all load situations: nKmax ≥ nmax

    Checking permitted shaft misalignment and restorative forces

    For all load situations the actual shaft misalignment must be less than the permitted shaft misalignment.

    Checking bore diameter, mounting geometry and coupling design

    The check must be made on the basis of the dimension tables. On request, couplings with adapted geometry can be provided.

    Checking shaft-hub connection

    Please refer to catalog section 3 for instructions.

    Checking temperature and chemically aggressive environment

    The permitted coupling temperature is specified in the Temperature Factor FT table. In the case of chemically aggressive environments, please consult the manufacturer.

    Особенности

    The ELPEX coupling is suitable for horizontal and vertical mounting positions or mounting at any required angle. The coupling parts can be arranged as required on the shafts to be connected.

    The split flexible rings can be changed without having to move the coupled machines.

    The flexible rings are mounted without backlash and give the coupling progressive torsional stiffness, i.e. torsional stiffness increases in proportion to coupling load.

    The ELPEX coupling is especially suitable for reversing operation or operation with changing directions of load.

    The coupling is delivered preassembled. The flexible rings are completely assembled. On the type ENG, the coupling halves have to be bolted together after the hub has been mounted. On the type EFG, after mounting the coupling hub, only the outer flange has to be connected to the machine.

    Outer flanges with different connection dimensions are available for the type EFG.

    If the flexible rings are irreparably damaged or worn, the metal parts can rotate freely against one another, they are not in contact with one another.

    Технические данные

    Power ratings

    Size

    Rated torque

    Maximum torque

    Overload torque

    Fatigue torque

    Dynamic torsional stiffness for 100 % capacity utilization

    Stiffness

    Permitted shaft misalignment at speed
    n = 1500 rpm

          

    Axial

    Radial

    Axial

    Radial

    Angle

     

    TKN

    TKmax

    TKOL

    TKW

    CTdyn

    Ca

    Cr

    ΔKa

    ΔKr

    ΔKw

     

    Nm

    Nm

    Nm

    Nm

    kNm/rad

    N/mm

    N/mm

    mm

    mm

    Degree

    270

    1600

    4800

    6400

    640

    22.0

    660

    770

    2.2

    2.2

    0.2

    320

    2800

    8400

    11200

    1120

    38.0

    780

    910

    2.6

    2.6

    0.2

    375

    4500

    13500

    18000

    1800

    63.0

    970

    1130

    3

    3

    0.2

    430

    7100

    21300

    28400

    2840

    97.0

    1160

    1350

    3.4

    3.4

    0.2

    500

    11200

    33600

    44800

    4480

    155

    1410

    1630

    3.8

    3.8

    0.2

    590

    18000

    54000

    72000

    7200

    240

    1710

    1990

    4.2

    4.2

    0.2

    690

    28000

    84000

    112000

    11200

    365

    2060

    2390

    4.6

    4.6

    0.2

    840

    45000

    135000

    180000

    18000

    685

    2570

    2990

    5

    5

    0.2

    970

    90000

    270000

    360000

    36000

    1100

    3020

    3510

    5.5

    5.5

    0.2



    The damping coefficient is Ψ = 1.1

    Torsional stiffness

    The dynamic torsional stiffness is load-dependent and increases in proportion to capacity utilization. The values specified in the selection table apply to a capacity utilization of 100 %. The following table shows the correction factors for different rated loads.

    CTdyn = CTdyn 100 % · FKC

     

    Capacity utilization TN / TKN

    20 %

    50 %

    60 %

    70 %

    80 %

    100 %

    200 %

    Correction factor FKC

    0.3

    0.56

    0.65

    0.74

    0.82

    1

    1.9



    Torsional stiffness also depends on the ambient temperature and the frequency and amplitude of the torsional vibration excitation. More precise torsional stiffness and damping parameters on request.

    Permitted shaft misalignment

    The permitted shaft misalignment depends on the operating speed. As the speed increases, lower shaft misalignment values are permitted. The following table shows the correction factors for different speeds.
    The maximum speed for the respective coupling size must be noted!

    ΔKperm = ΔK1500 · FKV

     

    Speed in rpm

     

    500

    1000

    1500

    3000

    Correction factor FKV

    1.6

    1.25

    1.0

    0.70