P R E P A R E D B Y

J I S H N U V

E N G I N E E R , B H E L - I S G

VIBRATING FEEDERS

1.INTRODUCTION

A vibrating feeder is a feeder/material conveying equipment consisting of a pan or trough to which a vibrating motion is imparted so that the material is impelled in a definite, controlled flow.

Normally, it is positioned under the opening in the bottom of a bin or below an emergency reclaim hopper in a stockpile

Generally its use should be avoided where the material is of sticky nature and which has the tendency to build up on the surface of pan/trough

2. TYPES OF VIBRATING FEEDERS

Vibrating feeder can be classified into two types based on the vibration imparting mechanism

2.1) Direct force exciter type

Direct force exciter (DFE) type vibrating feeder consists of an unbalanced weights assembly which imparts vibration to the trough due to the centrifugal force while rotating

The counterweights of the DFE are positioned in such a way that the unbalanced weights create transverse as well as longitudinal vibration of stroke sufficient to convey the material

2. TYPES OF VIBRATING FEEDERS

2.1.1) Constructional details of a DFE vibro-feeder

2. TYPES OF VIBRATING FEEDERS

2. TYPES OF VIBRATING FEEDERS

Trough/pan/deck is the tray on to which the material is fed from the hopper/bin. It consists of a mother plate (IS-2062 Gr-B/ST-42) and liner (SS-409M/Tiscral/SAILHARD) fixed on to it. The liners are fixed on to the mother plate normally using countersunk bolts and are torque tightened.

Direct force exciter:- Direct force exciter imparts the vibration to the deck due to the centrifugal force generated by the rotation of unbalanced weights.

2. TYPES OF VIBRATING FEEDERS

2. TYPES OF VIBRATING FEEDERS

The centrifugal forces F1 and F2 add to the resulting centrifugal force F, which produces linear oscillations. The stroke/amplitude and thereby the material flow rate are adjusted by varying the number of additional weights

2. TYPES OF VIBRATING FEEDERS

Cardan shaft is a universal joint shaft which permits axial as well as radial displacement.

Spring (Front and rear):- MOC of the spring commonly used is 50CrV4 or 55 SI7 or EN-45A

2. TYPES OF VIBRATING FEEDERS

2.2) Unbalanced motor type Unbalanced motor type vibrating feeder consists of 1 or 2 unbalanced motors

which impart vibration to the vibrating feeder

There are two methods of mounting of the unbalanced motors:

2.2.1) Side mounting:

2. TYPES OF VIBRATING FEEDERS

2.2.2) Back mounting

3. CAPACITY CALCULATION OF A VIBRATING FEEDER

3. CAPACITY CALCULATION OF A VIBRATING FEEDER

Material flow rate Q= ρ x A x V x 3600 x IF

Where

ρ = Density of the material conveyed in t/m^3

A= Cross sectional area of the material bed formed in m²

V= Flow velocity of the material in m/s; Minimum to be maintained is

A= B x D; B is the width of the tray over which the material bed formed/ inside skirt width; d is the throat opening height or skirt height at discharge side.

IF= Inclination factor depending on the angle of inclination

3. CAPACITY CALCULATION OF A VIBRATING FEEDER

Solved example.1 Design TPH:- 720TPH Material conveyed:- Coal Skirt height at discharge= 630mm Inside skirt width= 1580mm Flow velocity of material= 0.25m/s Angle of inclination of the tray w.r.t horizontal=12 ˚

Soln) Q= ρ x A x V x 3600 x IF ρ = 0.8t/m^3 A= B x D= 1.58 x 0.63= 0.9954m² V= 0.25m/s IF=1.3 Q=0.8 x 0.9954 x 0.25 x 1.3 x 3600=931.6944tph>720 tph Hence capacity selection of the model is ok

3. CAPACITY CALCULATION OF A VIBRATING FEEDER

Solved example.2) Design TPH:- 500TPH Material conveyed:- Coal Skirt height at discharge= 750mm Inside skirt width= 1500mm Flow velocity of material= 0.25m/s Angle of inclination of the tray w.r.t horizontal=10 ˚

Soln) Q= ρ x A x V x 3600 x IF ρ = 0.8t/m^3 A= B x D= 1.50 x 0.75= 1.125m² V= 0.25m/s IF=1.2 Q=0.8 x 1.125x 0.25 x 1.2 x 3600=972TPH>500 tph Hence capacity selection of the model is ok

4. MOTOR SELECTION OF A VIBRATING FEEDER

Power required for driving a vibrating feeder, P= (VW x a x N x 1.25)/(97400 x LRT)

Where

VW= Vibrating weight in kg

a= Amplitude of vibration in mm

LRT= Locked rotor torque ratio

N= RPM of the feeder

P is in kW

4. MOTOR SELECTION OF A VIBRATING FEEDER

Solved example.3) Vibrating weight:- 2600 kg Amplitude of vibration:- 4mm RPM of motor:- 1000RPM Starting torque maximum 2.0 times normal Motor selected:- 11kW

Soln) VW= 2600kg a=0. 4cm N= 1000 RPM LRT= 2.0

P= (2600 x 0.4 x 1000 x 1.25)/ (97400 x 2)=6.67kW Motor selected is 11kW. HENCE SELECTION OK