centrifugal feeder design

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Centrifugal Feeder Design

A centrifugal feeder, or rotary feeder, has a conical central driven rotor

surrounded by a circular bowl wall. The feeder separates parts utilizing

centrifugal force and the parts revolve with high speed and are pulled to the

outside of the bowl.

The design shown in this tutorial is a more sophisticated concept where an

inclined revolving disc brings the parts to the rim of a revolving bowl. This

concept allows for a series of qualifiers to gently orient the parts for transfer to a

downstream process.

Tutorial

Phase 1: General geometry

Phase 2: Drive design

Phase 3: Structure / Tooling

Warning This tutorial is to

serve as a guide covering most

design areas. User is to

consult and respect local

government regulations where

the unit is to operate.

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Phase 1 General geometry (1)

Operation:

Parts are metered from a prefeeder on the rotating disc.

The disc carries the parts to the rim of the rotating bowl in a single lane.

Fixed mechanical or pneumatic qualifiers orient and qualify the parts.

Improperly oriented parts are ejected from the rim to the disc for recirculation.Properly oriented parts moved out of the rim and out of the feeder.

Feed rate is affected mainly by:

The part size, its natural orientation and the desired orientation.

The disc and bowl speeds.

Part speed shall not exceed 100 meters/min to prevent damages.

DISC

BOWL

BOWL RIM

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Calculated rate:

The feed rate, R, can be approximated using:

L : the part longest dimension.

V : the part speed (or the bowl rotating speed x 3.14 x bowl rim diameter).P : the percentage of parts that will be in the desired orientation.

R = P V / L

A large bowl rim diameter will give time and space for the parts to be qualified and oriented. So bigger bowl means higher rate.

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Components (exploded view)

Tooling support

Tooling backup ring

Outer shell

Cone

Rotating disc

Disc hub

Rotating bowl

Bowl hub

Base

Shell attachment

Leveling foot

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Components (section view)

Static hub fixed on base

Ball bearings

Roller chain & sprocket

The bowl has a spherical inner surface. This allows the disc to rotate in an inclined orientation and maintains a small gap with the bowl around its perimeter

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Components (section view)

Roller chain & sprocket

Disc gearmotor

Bowl gearmotor

Torque limiter

Chain tensioner

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Phase 2 Drive design (1)

Drive

The drive is the assembly of components which rotates the disc and the bowl.

The disc rotates within the bowl at a speed that may be equal, higher or lower

than the bowl speed.

A speed difference between bowl and disc is used to improve loading of the bowl rim.

Disc gearmotor

Bowl gearmotor

Chain tensioner

Chain tensioner

Torque limiter

Torque limiter

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Drive

The static hub is bolted on the base.

The bowl is bolted on the bowl hub which rotates over the static hub.

A large sprocket drives the bowl hub.

Through the static hub, the drive shaft rotates the disc.

Base

Bowl hubSteel: UNS G10200

Drive shaftSteel: UNS G86200

Disc hubSteel: UNS G10200

Ball bearing

Static hubSteel: UNS G10200

Ball bearing

Large sprocket

Small sprocket

Torque limiter

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Disc drive

The gearmotor drives in rotation all items listed below and the parts carried by

the disc.Gearmotor output speed, Sd = (maximum part speed) / (3.14 x disc diameter) = {rpm}

Gearmotor output torque, Td = (Id + (Wp D2 / 4)) Ad + Tf = {N*m or lbs-in}

where:

Id : total rotational inertia of the items listed below

Wp : weight of the parts carried by the disc.D : disc diameterAd : required disc acceleration after a complete stop.

Ad = 3.14 Sd / (30 td )td : time to accelerate (below 2 sec.)Tf : frictional torque in the bearings

Torque limiter and roller chain are to be selected using this data.

Disc hub

DiscPVC

ConePVC

Driveshaft

Torque limiter

Sprocket Gearmotor

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Bowl drive

The gearmotor drives in rotation all items listed below and the parts carried by

the bowl.Gearmotor output speed, Sd = (maximum part speed) / (3.14 x bowl diameter) = {rpm}

Gearmotor output torque, Td = (Id + (Wp D2 / 4)) Ad + Tf = {N*m or lbs-in}

where:

Id : total rotational inertia of the items listed below

Wp : weight of the parts carried by the bowl.D : bowl diameterAd : required disc acceleration after a complete stop.

Ad = 3.14 Sd / (30 td )td : time to accelerate (below 2 sec.)Tf : frictional torque in the bearings

Torque limiter and roller chain are to be selected using this data.

Bowl hub

BowlCast aluminum

Bowl floorAluminum: UNS

A96061

Sprocket

Gearmotor


Phase 3 Structure/Tooling (1)

Structure

The structure supports all the rotating components and the outside shell. Its

construction is made of painted carbon steel (UNS K02600). The triangular

geometry allows easy mounting for most components.

Shell attachment

Base plate

Post

Leveling foot


Phase 3 Structure/Tooling (2)

Tooling

The tooling is all the components that qualify/orient the parts: mechanical

stoppers, air jets, pneumatic actuators, rotating wheel, . These components

are mounted on the tooling backup wall which serves also as an external guide.

This wall is mounted to the tooling support, and the tooling support is mounted on top of the outer shell.

Tooling support

Outer shell

Tooling backup wall