Upload
erhan88
View
159
Download
16
Embed Size (px)
DESCRIPTION
Mechatronics
Citation preview
Mechanical actuation systemMechanical actuation system
Learning outcome
At the end of the chapter, student should be able to:• Evaluate mechanical system involving:
– linkages– cams– gears– ratchet and pawl– belt and chain drives
Mechanical actuation systemMechanical actuation system
• Provide function as:– Motion converters
• rotational to linear
– Force amplification • lever
– Change of speed• gears
– Transfer of rotation axis• timing belt
– Particular types of motion• quick return mechanism, cam
Mechanical actuation systemMechanical actuation system
Types of motion• Translational, rotational and its combination• Degree of freedom, dof
dof = 6 – number of constrain
Mechanical actuation systemMechanical actuation system
Types of motion• Translational, rotational and its combination• Degree of freedom, dof
– dof = 6 – number of constrain– For planar
dof = 3(N-1) – 2L where:
N = number of linkL = number of join
Mechanical actuation systemMechanical actuation system
Kinematic chains• A link is part of a mechanism• A joint is a connection between link• Kinematic chain is a sequence of
link and joints
Mechanical actuation systemMechanical actuation system
Kinematic chains– Open loop kinematic chain
Mechanical actuation system
Kinematic chain– Slider crank mechanism
Mechanical actuation systemMechanical actuation system
Kinematic chain• The four bar chain• Grashof theorem• Lmax + Lmin La + Lb
• for one link to rotate
360 deg
Double crank
Double lever Lever crank
Mechanical actuation systemMechanical actuation system
Kinematic chainExample
Mechanical actuation systemMechanical actuation system
Cams• Rotates to provide reciprocating
motion to the follower
Mechanical actuation systemMechanical actuation system
• Cams
Mechanical actuation systemMechanical actuation system
• Cams
Mechanical actuation system
Lower Wheel
Upper Wheel
Upper wheel axis of rotation
Lower wheel axis of rotation
Driving pin
• Mechanism is used for achieving intermittent motions. • The component has two wheels; upper & lower• Continuous rotational movement of the lower wheel • Intermittent motion of the upper wheel; rotates step-wise
Geneva wheel
Mechanical actuation systemMechanical actuation system
Gear trains• Used to change speed or torque of rotating device
Mechanical actuation systemMechanical actuation system
Gear trains• Used to change speed or torque of rotating device
Mechanical actuation systemMechanical actuation system
Gear trains• G = A / B = dB / dA= B / A
G = A / B x B / C = A / C
Mechanical actuation systemMechanical actuation system
Epycylic gear train• Consists of groups of gears• 3 possibility of gear ratios
Mechanical actuation systemMechanical actuation system
Ratchet and pawl• Used to lock a mechanism when its holding a load
Mechanical actuation systemMechanical actuation system
Belt and chain drives–Torque on A, A = (T1 - T2) rA
–Torque on B, B = (T1 - T2) rB
– Power = (T1 - T2)v
–where belt speed v = A rA
Mechanical actuation systemMechanical actuation system
Belt and chain drives• Reversing drive