Centrifugal Feeder Design

Centrifugal Feeder Design

Centrifugal Feeder Design

A centrifugal feeder, or ‘rotary feeder’, has a

A centrifugal feeder, or ‘rotary feeder’, has a conical central driven rotorconical central driven rotor surrounded by a circular bowl wall. The feeder separates parts utilizing surrounded by a circular bowl wall. The feeder separates parts utilizing centrifugal force and the parts revolve

centrifugal force and the parts revolve with high speed and are pulled to thewith high speed and are pulled to the outside of the bowl.

outside of the bowl.

The design shown in this tutorial is a more sophisticated concept where an The design shown in this tutorial is a more sophisticated concept where an inclined revolving disc bring

inclined revolving disc brings the parts to the rim of a revolving bs the parts to the rim of a revolving bowl. Thisowl. This concept allows for a series

concept allows for a series of qualifiers to gently orient the parts for transfer of qualifiers to gently orient the parts for transfer to ato a downstream process.

downstream process.

Tutorial

Tutorial

Warning

Warning –– This This tutoriatutorial is tol is to serve as a guide covering most serve as a guide covering most design areas. User is to

design areas. User is to consult and respect local consult and respect local

government regulations where government regulations where the unit is to operate.

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

Phase 1 – General geometry (2)

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.

Phase 1 – General geometry (3)

Components (exploded view) 

Tooling support

Tooling backup ring

Outer shell Cone Rotating disc Disc hub Rotating bowl Bowl hub Base Shell attachment Leveling foot

Phase 1 – General geometry (4)

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

Phase 1 – General geometry (5)

Components (section view) 

Roller chain & sprocket

Disc gearmotor

Bowl gearmotor

Torque limiter

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.

Bowl gearmotor Chain tensioner

Torque limiter

Phase 2 – Drive design (2)

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 hub Steel: UNS G10200 Drive shaft Steel: UNS G86200 Disc hub Steel: UNS G10200 Ball bearing Static hub Steel: UNS G10200 Ball bearing Large sprocket Small sprocket Torque limiter

Phase 2 – Drive design (3)

Disc drive 

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

Gearmotor output speed , S_d = (maximum part speed) / (3.14 x disc diameter) = {rpm} Gearmotor output torque , T_d = (I_d + (W_p D2_{/ 4)) A}

d + Tf = {N*m or lbs-in}

where:

I_d : total rotational inertia of the items listed below W_p : weight of the parts carried by the disc.

D : disc diameter

A_d : required disc acceleration after a complete stop. A_d = 3.14 S_d / (30 t_d )

t_d : time to accelerate (below 2 sec.) T_f: frictional torque in the bearings

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

Disc hub Disc PVC Cone PVC Driveshaft

Phase 2 – Drive design (4)

Bowl drive 

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

Gearmotor output speed , S_d = (maximum part speed) / (3.14 x bowl diameter) = {rpm} Gearmotor output torque , T_d = (I_d + (W_p D2_{/ 4)) A}

d + Tf = {N*m or lbs-in}

where:

I_d : total rotational inertia of the items listed below W_p : weight of the parts carried by the bowl.

D : bowl diameter

A_d : required disc acceleration after a complete stop. A_d = 3.14 S_d / (30 t_d )

t_d : time to accelerate (below 2 sec.) T_f: frictional torque in the bearings

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

Bowl hub Bowl Cast aluminum Bowl floor Aluminum: 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

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