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May 2006 – T.Cicone 1/61 Couplings ME&M II
COUPLINGS – General presentation
• Connection.• Compensation (Positioning errors)• Disconnection (Automatic or manual)• Attenuation (Damping)
Couplings are used to connect two shafts.
Functions
Motor Working Machine
Couplings does not change operating parameters (Mt, n)
May 2006 – T.Cicone 2/61 Couplings ME&M II
COUPLINGS – General presentation
Compensation (Misalignment)
Radial
Angular
Axial
May 2006 – T.Cicone 3/61 Couplings ME&M II
PERMANENT
INTERMITTENT (CLUTCHES)
FIXED
MOBILE
AUTOMATED (Self-acting)
Rigid
Elastic
Hydraulic, pneumatic
Mechanical
Electrical
Speed (Centrifugal)
One-way (Overrunning)
Torque limiter (Slip Clutches
with elastomeric element
with metallic element
MECHANICALCOUPLINGS
COMMANDED
COUPLINGS – Classification
Electrical insulator
Connect/disconnect
During operation
2
May 2006 – T.Cicone 4/61 Couplings ME&M II
Transmitting torque – by friction
Tapered bushing
Transmitting torque – by shape/form
Transverse pin
Key or splines
Axial compensation ??
COUPLINGS – Fixed (Ribbed, Sleeve) Coupling
Rigid
May 2006 – T.Cicone 5/61 Couplings ME&M II
Key or spline transmitting torque
Ribbed Type Compression Coupling
COUPLINGS – Fixed (Ribbed) Coupling (Sleeve Type Couplings)
May 2006 – T.Cicone 6/61 Couplings ME&M II
COUPLINGS – Fixed (Ribbed) Coupling(Sleeve Type Couplings)
3
May 2006 – T.Cicone 7/61 Couplings ME&M II
Transmitting torque – by friction
Tapered bushing
COUPLINGS – Fixed (Ribbed) Coupling(Sleeve Type Couplings)
May 2006 – T.Cicone 8/61 Couplings ME&M II
COUPLINGS – Flange Coupling
Widespread
Simple, rigid
Transmit forces by shape/friction
May 2006 – T.Cicone 9/61 Couplings ME&M II
COUPLINGS – Flange Coupling
Screws in shearzD
MF tt
21 =
D
d
Safeguarding
4
May 2006 – T.Cicone 10/61 Couplings ME&M II
COUPLINGS – Gear Coupling
Total compensation
•Radial
•Axial
•Angular
Modified tooth
May 2006 – T.Cicone 11/61 Couplings ME&M II
COUPLINGS – Gear CouplingRequires Lubrication
SEAL – “O”-ringHigh load capacityNo damping
Simple or Double Gear Meshing
May 2006 – T.Cicone 12/61 Couplings ME&M II
COUPLINGS – Gear Coupling
CrowningTip reliefBacklashDifferent width
Simple -Double -
ENGAGEMENT
5
May 2006 – T.Cicone 13/61 Couplings ME&M II
COUPLINGS – Gear CouplingSIMPLE ENGAGEMENT
DOUBLE ENGAGEMENT
May 2006 – T.Cicone 14/61 Couplings ME&M II
COUPLINGS – Chain Coupling
Total compensation (Radial Axial Angular)
May 2006 – T.Cicone 15/61 Couplings ME&M II
COUPLINGS – Jaw Type Rigid Coupling
Shear
Contact pressure
Bending (eventually)Axial compensation
6
May 2006 – T.Cicone 16/61 Couplings ME&M II
COUPLINGS – Elastic Coupling
Metallic elements Elastomeric elementsNegligible hysterezis Hysterezis – important DAMPING
Jaw type Couplings
Flange with elastomeric bolt
Tyre Couplings (PERIFLEX)
Bibby (Grid Type) Couplings
Beam Springs
Sleeve Type Elastic
With damping
Without damping
With damping
Without dampingElastic
Characteristic
Linear
Non-linear
May 2006 – T.Cicone 17/61 Couplings ME&M II
COUPLINGS – Bibby (Grid Type) Coupling
1920 - BibbyElastic
Axial & Angular Compensation
May 2006 – T.Cicone 18/61 Couplings ME&M II
Mt
θ
Total compensation•Radial (0.5 …3mm)
•Axial (4 …20mm)
•Angular (< 1°)
COUPLINGS – Bibby (Grid Type) Coupling
7
May 2006 – T.Cicone 19/61 Couplings ME&M II
COUPLINGS – Sleeve Type Elastic CouplingSlit Type Elastic Coupling
Bellow Coupling
May 2006 – T.Cicone 20/61 Couplings ME&M II
COUPLINGS –Flexible Metallic CouplingsMembrane (Diaphragm) Coupling
Torque capacity 25,000 kW/1000 rpmSize 350 mm shaft diaSpeed 5,000 rpm
Facilitates mounting/dismountling
High torques due to metallicelastic elements used
May 2006 – T.Cicone 21/61 Couplings ME&M II
COUPLINGS –Flexible Metallic CouplingsMembrane Coupling
ARCOFLEX COUPLING (LENZE Ltd.)
8
May 2006 – T.Cicone 22/61 Couplings ME&M II
COUPLINGS –Compensating Metallic CouplingsSchmidt Coupling – Offset compensator
May 2006 – T.Cicone 23/61 Couplings ME&M II
COUPLINGS –Compensating Metallic CouplingsOldham Coupling – Offset compensator
Mechanical Efficiency < 1
Stresses ?Contact stressShearBending – very low
May 2006 – T.Cicone 24/61 Couplings ME&M II
COUPLINGS –Flexible Nonmetallic Couplings
• Highly elastic (Excellent shock absorber / High damping characteristics)
• High torque (Up to 100kNm)
• Lubrication free (dry operation)
• Tolerate large amounts of misalignments in all plans (multidirectional flexibility)
• Simple installation (without disturbing the coupled machines)
• Easy inspection (without dismantling)
• Progressive torsional stiffness curve (not all the elastic couplings)
• Backlash free (only some of elastic couplings)
• Electrical insulator (No Metal-to-Metal Contact)
• Resistant to oil, dirt, sand, moisture and grease
Elastomeric intermediate element
Jaw-type couplings Tyre couplings Bolt type elastic couplings
9
May 2006 – T.Cicone 25/61 Couplings ME&M II
John Crane Inc.
COUPLINGS –Tyre Coupling
The highest torque rate and damping capabilities
Rubber disc or envelope vulcanized to a hub
Total compensation•Radial (0.5mm)
•Axial (1 …3mm)
•Angular (max. 1°)
May 2006 – T.Cicone 26/61 Couplings ME&M II
COUPLINGS –Jaw Type CouplingsMt
θ
John Crane Inc.
May 2006 – T.Cicone 27/61 Couplings ME&M II
COUPLINGS –Jaw Type Couplings
10
May 2006 – T.Cicone 28/61 Couplings ME&M II
COUPLINGS –Jaw Type Couplings
• Standard Solid-Center Spider
• Open-Center Type
• Snap-Wrap
• Load Cushions
Spider designs
• Straight (US)
• Curved (Europe)
May 2006 – T.Cicone 29/61 Couplings ME&M II
COUPLINGS –Jaw Type CouplingsSpider design: SNAP-WRAP
John Crane Inc.
• Spider in shear• Mounting without shaft displacement• Requires an outer collar/ring – reduced speed
May 2006 – T.Cicone 30/61 Couplings ME&M II
COUPLINGS –Jaw Type Couplings
Outer Collar
Snap-Wrap Spider
Spider in shear (Jaw-in-shear Coupling)
Compensation
•Radial (1 …4mm)
•Angular (up to 2°)
Max. Torque: 40kNm
for 360mm bore.
11
May 2006 – T.Cicone 31/61 Couplings ME&M II
COUPLINGS –Jaw Type CouplingsSpider in shear (Jaw-in-shear Coupling)
Compensation
•Radial (up to 3mm)
•Axial (limited)
•Angular (up to 1°)
•Torsional wind-up (15°)
• One-piece solid
• One-piece split
• Two-piece with retaining ring
May 2006 – T.Cicone 32/61 Couplings ME&M II
COUPLINGS –Jaw Type Couplings
Spider in shearSpider in compression
FAIL-SAFE !
May 2006 – T.Cicone 33/61 Couplings ME&M II
COUPLINGS –Bolt Couplings
12
May 2006 – T.Cicone 34/61 Couplings ME&M II
COUPLINGS – Universal Joint
Hooke (Cardan ) articulation
spiderYoke
Intermediate splined shaft
bearing
Highly angular and axial compensation
No synchronism !
βωωβωω
coscos
1max2
1min2
==
May 2006 – T.Cicone 35/61 Couplings ME&M II
COUPLINGS – Universal JointTandem mounting
May 2006 – T.Cicone 36/61 Couplings ME&M II
COUPLINGS – Universal Joint
Syncronisms obtained ONLY for tandem mounting AND IF
•The axis of all shaft sections lie in the same plane
•The bearing bores of the inboard yokes of the center section lie in the same plane.
•The bend angles β1 and β2 are equal.
13
May 2006 – T.Cicone 37/61 Couplings ME&M II
BRAKE
CLUTCH
BRAKES & CLUTCHESProvide magnetic, hydraulic, mechanical connection between two elements
May 2006 – T.Cicone 38/61 Couplings ME&M II
Internal Expanding Shoes External Contracting Shoes
BRAKES
RIM Types
Interruptible connections between a rotating element & a non-rotating ground plate or element
May 2006 – T.Cicone 39/61 Couplings ME&M II
BRAKES
BAND TypeCONE Type
DISK Type
14
May 2006 – T.Cicone 40/61 Couplings ME&M II
May 2006 – T.Cicone 41/61 Couplings ME&M II
RIM BRAKE (INTERNAL EXPANDING)
ShoeDrum
May 2006 – T.Cicone 42/61 Couplings ME&M II
RIM BRAKE (INTERNAL EXPANDING)
=
app
θθ
sinsin
maxPressure distribution based on FEM modelling
Long shoe brake model
15
May 2006 – T.Cicone 43/61 Couplings ME&M II
(MULTIPLE) DISK BRAKE
May 2006 – T.Cicone 44/61 Couplings ME&M II
CLUTCHES - Generalities
Connect & disconnect shafts at will (during rotation)
• to allow a high-inertia load to be started with a low-torque prime-mover than would be required if it were directly connected
• an emergency disconnect device to decouple in the case of a machine jam
• to maintain a constant torque on a shaft
Functions
May 2006 – T.Cicone 45/61 Couplings ME&M II
• means of actuation
• means of energy transfer
• method of engagement
• Mechanical• Hydraulic/Pneumatic• Electrical• Automatic
CLUTCHES - Classification
• Positive mechanical contact• Friction• Hydraulic• Electromagnetic
• Synchronous• Non- synchronous
16
May 2006 – T.Cicone 46/61 Couplings ME&M II
CLUTCHES
POSITIVE CLUTCHES = Positive mechanical contact (toothed clutches)
Interlocked teeth Jaw type shape
Compact
(OLDHAM coupling)
No adjustment required Do not introduce important axial forces
No slipSynchronism required One element slides axially
(Hirth)
May 2006 – T.Cicone 47/61 Couplings ME&M II
CLUTCHES - Positive
square-jaw (claw type)
spiral-jaw Short axial displacement(Hirth radial teeth)
May 2006 – T.Cicone 48/61 Couplings ME&M II
One-directional
Reduced clashing
Bicycle – rear sprocket – rear wheel
CLUTCHES - Positive
Bi-directional
Clashing
Can be also trapezoidal
17
May 2006 – T.Cicone 49/61 Couplings ME&M II
CLUTCHES - FrictionMulti-disk friction clutch
Slip clutch
May 2006 – T.Cicone 50/61 Couplings ME&M II
Constant Pressure Analysis (elastic plates)
( )22iomn rrpF −=π
mnio
ionmAf rF
rrrrFArpM µµµ =
−−
== ∫ 22
33
32d
Constant Wear Analysis (rigid plates) Vpwear ⋅≈
Vpconst=δdepth irppr max=ωrV =
( ) mnio
nioiAf rFrrFrrrpArpM µµπµµ =+
=−== ∫ 2d 22
max
Friction CLUTCHES - Pressure
ri
ro
r
dr
May 2006 – T.Cicone 51/61 Couplings ME&M II
• high coefficient of friction• resistant to wear • sufficient compressive strength• temperature resistance (against
seizure)• thermal stability• good thermal conductivity• good elastic properties
Friction CLUTCHES - Materials
Characteristics
• Disks Lining– Molded
• Polymeric resin– Powder fillers– Fibrous material
– Woven– Sintered
• Higher temperature resistance• Compressive strength
– Greater than molded or woven
18
May 2006 – T.Cicone 52/61 Couplings ME&M II
Dynamics of Coupling
Ta
ωn ω1
ω2
ω
M
Mn
Mrez
Ma
t
t
Mω
t
Lf
La
aa T
IIM 2222ωε ==
( ) tta MMMM 1max −=−= β
ttcf MMMM β===max
( ) ta M
nIT130
2
−=
βπ
1) Engagement time
][3600
WzL
P ff =3) Power dissipated
][60
1 WTnML atf
πβ=2) Friction work
at
T
tf TMMLa
10
21d ωβθ
ω
== ∫
May 2006 – T.Cicone 53/61 Couplings ME&M II
Disk Friction CLUTCHES
May 2006 – T.Cicone 54/61 Couplings ME&M II
Automotive Clutch
19
May 2006 – T.Cicone 55/61 Couplings ME&M II
SLIP CLUTCH
May 2006 – T.Cicone 56/61 Couplings ME&M II
OVERRUNING CLUTCHES
free-wheeling orone-way clutches
ratchet wheel
May 2006 – T.Cicone 57/61 Couplings ME&M II
OVERRUNING CLUTCHES
20
May 2006 – T.Cicone 58/61 Couplings ME&M II
HYDRODYNAMIC CLUTCHES (inertia forces)
Start-up clutches Torque limiter Fottinger 1904
May 2006 – T.Cicone 59/61 Couplings ME&M II
VISCO-COUPLINGS
May 2006 – T.Cicone 60/61 Couplings ME&M II
VISCO-COUPLINGS
4+6 driving elements
2+3 driven elements
5 - fluid