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Chapter 3 1 Conveyors

This document discusses different types of conveying equipment used to transport materials continuously over fixed paths. It describes traction conveyors that use belts, chains, or other means of positive traction to move materials, as well as tractionless conveyors like chutes, rollers, screws, and pneumatic systems. Specific conveyor types are then explained in more detail, covering their components, operation principles, and typical applications. Design considerations for belt conveyors like capacity calculations, resistance forces, belt tensions, and power requirements are also outlined.

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Matthew Mhlongo
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© © All Rights Reserved
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Download as PDF, TXT or read online on Scribd
235 views

Chapter 3 1 Conveyors

This document discusses different types of conveying equipment used to transport materials continuously over fixed paths. It describes traction conveyors that use belts, chains, or other means of positive traction to move materials, as well as tractionless conveyors like chutes, rollers, screws, and pneumatic systems. Specific conveyor types are then explained in more detail, covering their components, operation principles, and typical applications. Design considerations for belt conveyors like capacity calculations, resistance forces, belt tensions, and power requirements are also outlined.

Uploaded by

Matthew Mhlongo
Copyright
© © All Rights Reserved
Available Formats
Download as PDF, TXT or read online on Scribd
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Conveying Equipment

By MA.
Introduction
• Conveying Equipment is a group of machines which
move materials in relatively large quantities in a
continuous flow between specific locations over a
fixed path.
• There are over 400 types of conveyors.
• The main groups of conveying equipment classified
by their design features are:
Traction-type Conveyors
Traction less-type Conveyors

By MA.
Introduction
Traction-type Conveyors
The main types of traction type conveyors are:
• Belt conveyors
• Chain conveyors
• Push through conveyors
• Indexing conveyors
• Cable conveyors

By MA.
Introduction
Traction less-type Conveyors
The main types of traction less type conveyors are:
• Sliding- friction gravity (Chute) conveyors,
• roller conveyors,
• screw or spiral conveyors,
• twin- helical conveyors,
• vibrating and oscillating conveyors,
• hydraulic transport systems,
• pneumatic conveyors, etc. form the bulk of traction
less type conveyors.

By MA.
BELT
CONVEYORS

By MA 5
By MA 6
CHAIN
CONVEYORS

By MA 7
APRON CONVEYORS

By MA 8
ROLLER
CONVEYORS

By MA.
Belt Driven Live Roller Conveyors

Chain Driven Live Roller Conveyors

By MA.
ROLLER cont…

Gravity roller conveyors

By MA.
By MA 12
SCREW OR SPIRAL
CONVEYORS

By MA.
Vibrating

By MA.
Power Driven Roller cont…

By MA.
Belt Conveyors
• Belt conveyors are the most versatile and
widely used of all conveyors.
• They are suitable for handling a wide
variety of materials.
• They can handle a wide range of
capacities over longer distance than
possible with other types of conveyor
systems.
• They are adaptable for performing
numerous other functions such as
weighing, blending (combination)
sampling and stock piling.
Cont’d
• The belt conveyor is composed of the belt,
the idlers, the pulleys, the drive
equipment, the take-up and the supporting
structure.
Conveyor Belting
The belt cover is made of special wear-and
impact- resisting rubber compound with
cord breaker strips imbedded in tough
rubber

Typical Cross-section of the Conveyor Belt


Cont’d
1.Cotton-Fabric Ply-Constructed Belting:
is the most widely used kind of rubber
covered conveyor belt, in which the fiber is
made up of a number of layers or plies of
woven cotton fabrics of various weight.
2. Cord Belts are made up of longitudinal
fibers or steel cords imbedded in rubber
provide greater strength, more flexibility and
somewhat greater impact resistance.
3. Heat Service Belts are available for jobs
where hot materials up to 1200C must be
handled.
Cont’d
Belt Idlers

Idlers must be selected to properly protect


and support the belt and load to be carried.
Cont’d

Fig. Types of Idlers


Drives

• Practically all belt conveyors are driven by


an electric motor directly connected to a
speed reducer unit through a flexible
coupling.
• A high-speed motor, which costs less and
occupies less space, is preferred to a slow
speed motor.
Cont’d

Belt Conveyer Drive Arrangements


Take-ups
• Allow for stretch and shrinkage of the
belt due to variation of temperature
and atmospheric pressure.
• Insure that the maximum tension in
the belt is sufficient to prevent undue
sag between idlers
• Insure that the tension in the belt in
the back of the drive pulley is
sufficient to permit such pulley to
transmit the load
Cont’d

Types of Take-ups for Belt Conveyors


Pulleys, Shafts and Bearings
• Pulleys for belt conveyors are usually
welded steel, drum types, for maximum
strength, minimum weight, and for
resistance to shock during handling and
operation.
• The factors involved in pulley diameter
selection include the amount of wrap, belt
tension at the pulley, space available,
characteristics of the materials handled,
belt life expectancy, shaft and bearing size
and size and ratio of reducer.
Cont’d

• The shaft and the pulley are treated as a


single structure.
• The resultant force on the bearing (shaft)
is the vector sum of belt tensions, pulley
weight, and weight of the shaft.
 Note that the force on the shaft is
opposite to the direction of the resultant
force R.
Force on the shaft
R 5250
=  2625 =kg
2 2

T=3800kg

t=1600kg

W=1300kg

T=3800
t=1600

R=5250 W=1300
Typical Arrangements
Discharging Materials from the
Belt
Magnetic Separation
Typical Cross-sections
Belt Conveyor Design Calculation
Basic Data Requirements
1. The material to be handled
2. Capacity peak or surge rate expressed in
ton/hr
3. Path of travel
4. Feeding and discharge conditions
5. Operating conditions
6. Required life of installation
Preliminary Check
 Is the belt conveyor is suitable for the
material?
 Is the angle of inclination is within safe
limits? etc.
Capacity of a Belt Conveyor
a.If the material to be conveyed is a unit load
Q [tons/h]

Q 3.6where
qBv
q = distributed load [kg/m2]

B = width of the belt [m]


b. If the material to be conveyed is in bulk
v = velocity of the belt [m/s]
load, Q [tons/h].
Q where
3.6Av
 = the density of the mat [kg/m3]
A = the cross-sectional area of the material being
conveyed [m2]
Cont’d
• If the belt conveyor has an inclination ,
then the capacity Q will be reduced by a
factor p.
Q  pQ

Cross-sectional Loading on Belt Conveyors

(B + 4) B 2
Af =
110
Ac = 2 A f
Where A f = cross-sectional area of the material
on the flat belt [m2]
Ac = cross-sectional area of the material on the
troughed belt [m2]
B = belt width [m]

The assumptions used to arrive at the above


formula are a 200 inclination of rollers and
angle of repose (relax) of material to be 300.
Resistance Forces
a, Frictional force on the moving parts
(belt, idlers, drum, etc)
r1  fq s l
' '' ' ''
r1 r  r  fq l  fq l
1 1 s s

where q s = frictional forces due to moving parts


f = coefficient of frictional force of the
idlers
r1 = weight of the moving part in kg/m of the
belt
l = belt length between two drum centers [m]
Cont’d
b, Frictional force due to material
transport
r2  fq m l m
Where, q
m = weight of material transported [kg/m of belt]
l m = the distance that the material is transported [m].

c, Force required to overcome the


level difference
r3 q m H
Where, H = elevation difference
d, Discharging force Cont’d

Fixed discharger:
r4 aq m
Mobile discharger:

r5 bqm
where a and b are discharge coefficients
Cont’d
e. Fixed resistance:
It takes into consideration frictional forces at
the conveyor terminal bearing, at the
conveyor loading skirt (avoid) and other
minor power absorbing terms.

l o 60  0.2l
r1  fq s (l  l o )
r2  fq m (l m  l o )
The total resistance to motion, R,

R r1  r2  r3  r4 (fixed discharge)

r1  r2  r3  r5 (mobile discharge)


Belt Tension
The belt tensions, in addition to their effect
on power requirements they also influence
the design and selection of all component
parts.

Loads on Drive Pulleys


Cont’d

We know that R =T-t. The relationship between


T and t may be expressed T

e
t
t min 50nB Cont’d
where

 = coefficient of friction

 = wrap angle
n = number of cords of the belt
B = the width of the belt in meters
Cont’d
Belt Tension on a Horizontal Belt Conv
'
2To 2(t  r1  Pn )

Where Pn = reduction due to the weight


of the belt. The slack side tension, t,
must exert sufficient pressure
between the belt and the driving
pulley to transmit the required power
with out slippage. The adhesion
(wheel grip) between the belt and the
driving pulley can be increased by
i. Changing the pulley;
ii. Increasing the arc of contact and;
iii. Using stretchers (take ups).

Illustration to Increase the Arc of Contact


Number of Fibers

After calculating the tension, T, it is


possible to calculate the number of
fibers in the nucleus of the belt

T
n
KB where

n = number of fibers
K = resistance of one fiber per
unit width (5 to 7 kg/cm) and
B = width of the belt
Power Requirement

In order to determine the required


motor power [kW], we use the total
resistance R and calculate the power
N. Where, v = speed of the
Rv belt in m/s.
N=
102

 = efficiency of the electromotor


•Thank you
•End of this
portion

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