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Lecture 02 Assembly Automation Vibratory Feeders

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Introduction Vibratory feeder Mechanics of Vibratory Feeder

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Force acting on vibratory feeding

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for sliding up the track to occur Where condition for forward sliding up the track to occur is, therefore, given by combining Equation Similarly, it can be shown that, for backward sliding to occur during the vibration cycle (Eq: 1) (Eq: 2) (Eq: 3) (Eq: 4)

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Normal track acceleration The operating conditions of a vibratory conveyor may be expressed in terms of the dimensionless normal track acceleration A n /g n, where A n is the normal track acceleration (A n = a n 2 = a 0 2 sin ), g n the normal acceleration due to gravity G n =(g cos ), and g the acceleration due to gravity (9.81 m/sec2) (Eq: 5)

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Substitution of Equation 5 in Equation 3 and Equation 4 gives, for forward sliding, for backward sliding The limiting condition for forward conveying to occur is given by comparing Equation 6 and Equation 7. Thus, for forward conveying Force acting on vibratory feeding (Eq: 6) (Eq: 7) (Eq: 8)

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With sufficiently large vibration amplitudes, the part will leave the track and hop forward during each cycle. This can occur only when the normal reaction N between the part and the track becomes zero. and, therefore, for the part to leave the track, Force acting on vibratory feeding (Eq: 10) (Eq: 9)

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For s= 0.8, = 3 deg,=30 deg find An/gn for forward sliding and backward sliding

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Limiting conditions 4.7 1 0.34 0.8

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Effect of various parameters On conveying velocity (v m ) where fv m =constant Frequency (f) Track Acceleration (A n /g n ) Vibrating angle ( ) Track angle ( ) Coefficient of friction ()

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Frequency & track acceleration

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Vibration angle

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Track angle

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Coefficient of friction

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Typical part motions

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Effective length of the hop (J)

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Effective height of the hop(H)

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Load sensitivity

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Solution of load sensitivity Load detector switch Modification to the feeder By changing spring stiffness Use on/off control Sensor control

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Spiral elevators

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Balanced feeders

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Orientation of Parts Active Orienting devices-reorientation Passive Orienting devices-rejection base -In bowl -Out bowl

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Passive-in bowl

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Typical Orienting systems

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Orienting systems- Washers

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Orientation Machined washer

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Orientation cup shaped parts

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Orientation truncated cones

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Orientation U-shaped parts

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Orientation narrowed track

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Wall projection and narrowed track

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Active Orienting systems

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Analysis of orienting systems

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Natural resting aspect

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Probability of orientation

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Natural resting aspect Assumptions Surfaces can be divided in to two categories Soft surfaces Hard surfaces Probability that the part come to rest in a particular natural resting aspect depends on two factors Energy barrier tending to prevent a change of aspect Amount of energy possessed by the part when it begins to fall Parts are being dropped from sufficient height

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Natural resting aspect

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Out-of-Bowl tooling

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