Dunlop Conveyor Belt Design Manual

Dunlop Conveyor Belt Design Manual

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DUNLOP Belting

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Conveyor Belt Design Manual

INDEX

Introduction Dunlop Conveyor Belting Range Belting Characteristics Additional Features SABS Specifications Conveyor Belt Design Step By Step Example of Belt Tension Calculation Table 1: Table of Symbols Table 2: Material Characteristics Table 2(a): Typical Flowability Determination of Conveyor Capacities Table 3: Capacities of Troughed Belt Conveyors Table 4: Recommended Maximum Belt Speed for Normal Use Table 5: Recommended Idler Spacing Table 6: Friction Factors Table 7: Sag Factor Table 7(a): Recommended Percentage Sag Table 8: Estimated Belt Mass Table 9: Typical Mass of Rotating Parts of Idlers Table 10: Mass of Moving Parts Table 11: Drive Factor Conveyor Belt Selection Table 12: Maximum Recommended Operating Tensions Table 13: Recommended Minimum Pulley Diameters Table 14: Load Support Table 15: Maximum Number of Plies Recommended for Correct Empty Belt Troughing Table 16: Carcass Thickness Table 17: Mass of Belt Carcass Table 18: Mass of Covers per mm of Thickness Rate of Wear Graph Table 19: Minimum Belt Top Cover Gauge Guide Table 20: Belt Modulus Tabulator Calculations Sheet 1: Empty Belt Sheet 2: Fully Loaded Belt Sheet 3: Non-Declines Loaded Sheet 4: Declines Loaded Tension Tabulator Vertical Curves Maximum Incline Angle Graph for Estimating Belt Length/Rolled Belt Diameter Useful Data Conversion Factors Conveyor Belting Design Manual

INTRODUCTION

Dunlop Africa Industrial Products is the leading designer and manufacturer of industrial rubber products in South Africa. In fact our belting systems can be seen on some highly productive plants all around the globe.

What more can you expect, when you consider that our belts have been designed and fabricated by some of the best engineers in the industry and from only the finest raw materials.

Using the most current technology, many components have taken years of refinement to attain such technological precision. And every belt is guaranteed to provide maximum performance and maximum life.

http://www.ckit.co.za/Secure/Conveyor/Troughed/belt_tension/Dunlop/Belting%20B...

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And with some 750 000 various specifications available, you can expect to find the right belt for your requirements no matter how specialised.

This manual contains all the elements, formulae and tables you need to specify the exact belt. It has been compiled for your benefit, as a quick reference book for easy selection. If however you have an application not covered in the following pages, please contact Dunlop Africa Industrial Products. A team of experienced and helpful engineers will be pleased to assist you.

Our range of excellent products, competitive pricing and impeccable service, has earned Dunlop Africa Industrial Products the reputation of being the market's first choice.

DUNLOP CONVEYOR BELTING RANGE

Dunlop Africa Industrial Products manufactures the most comprehensive range of conveyor belting in South Africa.

Multi-ply rubber covered conveyor belting

z

XT textile reinforced conveyor belting with grade N covers

z

XT textile reinforced conveyor belting with grade M cut resistant covers

z

Phoenix heat resistant belting

z

Super Phoenix heat resistant belting

z

Delta Hete heat resistant belting

z

Fire resistant belting

z

Rufftop belting

z

Riffled concentrator belting

z

Grey food belting

z

Salmon pink food belting

z

Endless belts

z

Woodmaster

z

Oil resistant belting

Solid woven PVC belting

z

Standard solid woven PVC belting

z

Nitrile covered PVC belting

Steelcord belting

z

Fire resistant steelcord belting

z

Steelcord reinforced conveyor belting with cut resistant type M covers

z

Steelcord reinforced conveyor belting with type N covers

z

Steelcord reinforced conveyor belting with "Ripstop" protection

z

Steelcord reinforced conveyor belting with rip detection loops

Flinger belts


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z


High speed truly endless belting

BELTING CHARACTERISTICS

XT Rubber Conveyor Belting (conforms to SABS 1173-1977)

z

From the early days of cotton duck plies, progress has been made in the manufacture of all-synthetic plies offering many advantages.

z

The range of strengths has been greatly increased, with improvements in the flexible structure. The modern multi-ply belt is manufactured with a synthetic fibre carcass in a wide slab, then slit to width as required for individual orders.

z

A wide range of belt specifications is available with current belt constructions having versatile applications.

z

The standard XT belting (Grade N) incorporates covers suitable for the handling of most abrasive materials, having a blend of natural and synthetic rubber.

Cut resistant XT Rubber Belting

z

Grade M Belts have covers with high natural rubber content recommended for belts operating under extremely arduous conditions where cutting and gouging of covers occurs.

Phoenix Heat Resistant Belting

z

Phoenix Heat Resistant belting covers are styrene butadiene based and are recommended for belts handling materials with temperatures up to 1200C.

Super Phoenix Heat Resistant Belting

z

Super Phoenix Heat Resistant belts have chlorobutyl covers and are recommended for belts handling materials with temperatures of up to 1700C.

Delta Hete Heat Resistant Belting

z

Delta Hete heat resistant belting with EPDM synthetic rubber covers in a formulation developed to allow conveying materials of temperatures up to 2000C.

Fire Resistant Belting (conforms to SABS 971-1980)

z

Fire Resistant XT belting is manufactured with covers containing neoprene and multi-ply carcass constructions to meet the stringent standards for safety in all underground mining industries and is therefore particularly suited to shaft applications.

Woodmaster

z

This belt has been especially developed for the Timber Industry. The rubber has been compounded to provide resistance to oil and resin, and is non-staining.

Rufftop Belting

z

This is a range of rough top package belting, of two or three ply all-synthetic carcass belts with deep impression rubber covers. The range is ideal for the packaging and warehousing industries and baggage handling installations such as airports and railway stations etc.

Riffled Concentrator Belts

z

Riffled conveyor belting has raised edges, is 1 500 mm wide and available in endless form. These belts are uniquely applied at gold mine concentrators.

Food Quality Belting

z

Food quality belting is ideal where foodstuffs come into direct contact with the belt surface. This range of belting is manufactured from non-toxic materials and is resistant to oils, fats and staining, and meets the strict hygiene requirements laid down by the food processing industry. The two types available are Grey food belting and Salmon pink belting


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Endless Belting

z

The complete XT range can be made available as factory spliced endless belts. These belts are recommended for short conveyor installations. (Suitable for lengths up to 50 in.)

Flinger Belts

z

Flinger Belts are fitted to flinger conveyors, the primary function of which is to disperse the discharging material over a wide area, thus minimising heap build-up below the main conveyor. The flinging effect is achieved by running the flinger belt at a high speed in a U configuration. Flinger belts are built and cured on a drum to eliminate a spliced join.

Solid Woven (PVC) Belting (conforms to SABS 971-1980)

z

Commonly known as 'Vinyplast' solid woven PVC. The construction has inherently high fastener holding qualities. The belting is constructed of polyester and nylon with a cotton armouring, is impregnated with PVC and has PVC covers. These belts have been specially developed to resist impact, tear, rot and abrasion and to meet the most stringent flame-resistant standards.

Nitrile Covered (PVC) Belting

z

The nitrile cover on solid woven PVC belts is specially designed to meet the SABS specifications for use in mines, where a fire hazard exists. In general the nitrile cover has good flame-retardant properties and oil, abrasion and heat resistance.

Steelcord Belting (conforms to SABS 1366-1982)

z

Steelcord conveyor belting is designed for very long hauls where textile reinforcement would either not achieve the requisite strength or would have too high an elongation at reference load. Resistance to severe shock and exceptional tensile loading is achieved by the wire reinforcement encased between thick top and bottom covers of the highest quality rubber. These belts are designed to conform to or exceed the requirements of stringent standards and offer a long belt life.

Fire Resistant Steelcord Belting (Conforms to SABS 1366. 1982 type F).

z

Steelcord belting of fire-resistant quality is made with specially compounded rubbers which render it self extinguishing. Fireresistant steelcord belting offers great advantages in maintenance-free operation and long belt life for conveyors situated in fiery mines.

Oil Resistant Belting

z

Oil resistant belting provides easily cleanable covers of either nitrile or neoprene on all-synthetic fabric plies. Choice of covers gives maximum resistance to mineral and vegetable oils thus permitting the user to convey a wide variety of materials containing mineral and vegetable oils.

ADDITIONAL FEATURES

1.

Ri p P ro rotector

As an additional feature rip protection can be incorporated into the belt by means of arranging strong nylon fibres transversely or by inclusion of electronic loops. The textile rip protection can be built into the belt in 2-metre lengths at regular intervals or over the full length of the belt.

2.

Shuro Shuron n Brea Breaker ker Ply (XT (XT belt belting ing) )

For applications where the lump size of the material carried is large and where adverse loading conditions exist, an open weave breaker ply can be incorporated below the top cover as an extra protection for the carcass.

3.

Chevr Chevron on Breake Breaker r (XT (XT belt belting ing) )

This incorporates steel tyre cord in a 'V shape, as a rip protection, at intervals over the belt length. Particularly recommended for XT belting where arduous conditions are experienced i.e. slag transportation.

4.

Belt Ed Edges

Many conveyor belts track off at some stage of their lives, causing edge damage to a greater or lesser extent. Belts can be supplied with either slit or moulded edges.

Slit edges: All-synthetic constructed carcasses have good resistance to edge chafing, due to modern fibre construction In addition there is minimal penetration of moisture to the carcass and therefore no problem with carrying out hot vulcanised splices or repairs.


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Moulded edges: A moulded rubber edge can be provided to protect the carcass from acids, chemicals and oils. In most applications a moulded edge is unnecessary as synthetic fibres will not rot or be degraded by mildew.

SABS SPECIFICATIONS

Dunlop Africa Industrial Products conveyor belting complies with the stringent standards as laid down by the SABS.

1.

SABS 1173-1977 - General purpose textile reinforced conveyor belting.

2.

SABS 971-1980 - Fire-resistant textile reinforced conveyor belting.

3.

SABS 1366-1 982- Steelcord reinforced conveyor belting.

The above specifications cover the requirements of the various conveyor belts and are classified according to the minimum full thickness breaking strength of the finished belting in kilonewtons per metre width.

Further information regarding SABS specifications will be supplied on request.

CONVEYOR BELT DESIGN

Introduction

A conveyor belt comprises two main components:

1.

Reinforcement or a carcass which provides the tensile strength of the belt, imparts rigidity for load support and provides a means

2.

of joining the belt. An elastometric cover which protects the carcass against damage from the material being conveyed and provides a satisfactory surface for transmitting the drive power to the carcass.

In selecting the most suitable belt for a particular application, several factors have to be considered:

1.

The tensile strength of the belt carcass must be adequate to transmit the power required in conveying the material over the distance involved.

2.

3.

The belt carcass selected must have the characteristics necessary to: a.

provide load support for the duty.

b.

conform to the contour of the troughing idlers when empty, and

c.

flex satisfactorily around the pulleys used on the conveyor installation.

The quality and gauge of cover material must be suitable to withstand the physical and chemical effects of the material conveyed.

Belt Tensions

In order to calculate the maximum belt tension and hence the strength of belt that is required, it is first necessary to calculate the effective tension. This is the force required to move the conveyor and the load it is conveying at constant speed. Since the calculation of effective tension is based on a constant speed conveyor, the forces required to move the conveyor and material are only those to overcome frictional resistance and gravitational force.

Mass of Moving Parts

For the sake of simplicity the conveyor is considered to be made up of interconnected unit length components all of equal mass. The mass of each of these units is called the mass of the moving parts and is calculated by adding the total mass of the belting, the rotating mass of all the carrying and return idlers and the rotating mass of all pulleys. This total is divided by the horizontal length of the conveyor to get the mean mass of all the components. At the outset the belt idlers and pulleys have not been selected and hence no mass for these components can be determined. Therefore the mass of the moving parts is selected from the tabulated values to be found in Table 10.

Mass of the load per unit length

As is the case with the components the load that is conveyed is considered to be evenly distributed along the length of the conveyor. Given the peak capacity in ton per hour the mass of the load per unit length is given by:

Q = 0,278

τ S

or

Q=

τ 3,600S

The effective tension is made up of 4 components

z

The tension to move the empty belt T x

z

The tension to move the load horizontally T y

z

The tension to raise or lower the load T z

z

The tension to overcome the resistance of accessories T u


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The effective tension is the sum of these four components

Te = Tx + Ty + Tz +Tu

Tx = 9,8G x f x x Lc

Tz = 9,8Q x H

Various conveyor accessories that add resistance to belt movement are standard on most conveyors. The most common are skirtboards at the loading point and belt scrapers. Other accessories include movable trippers and belt plows.

Tension required to overcome the resistance of skirtboards Tus

9,8f s x Q x L s

Tus =

S x b²

Tension to overcome the resistance of scrapers

Tuc = A x ρ x f c

In the case of a belt plow the additional tension required to overcome the resistance of each plow is

Tup = 1,5W

Moving trippers require additional pulleys in the system and therefore add tension. If the mass of the additional pulleys has been included in the mass of moving parts then no additional tension is added. However, if a separate calculation of the tension to overcome the resistance of the additional pulleys is required this can be determined for each additional pulley as follows

Tut = 0,01

do x T1 Dt

Corrected length Lc

Short conveyors require relatively more force to overcome frictional resistance than longer conveyors and therefore an adjustment is made to the length of the conveyor used in determining the effective tension. The adjusted length is always greater than the actual horizontal length.

LC = L + 70

The length correction factor is

C=

Lc L

All conveyors require an additional tension in the belt to enable the drive pulley to transmit the effective tension into the belt without slipping. This tension, termed the slack side tension T 2, is induced by the take-up system. In the case of a simple horizontal conveyor the maximum belt tension T 1 is the sum of the effective tension Te and the slack side tension T 2

ie: T1 = Te + T2

T1 is the tight side tension and 12 is the slack side tension

For a more complex conveyor profile that is inclined, additional tensions are induced due to the mass of the belt on the slope. This tension is termed the slope tension 'h and increases the total tension.

Thus T 1 = Te + T2 + Th


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The slack side tension is determined by consideration of two conditions that must be met in any conveyor. The first condition is that there must be sufficient tension on the slack side to prevent belt slip on the drive. The second condition is that there must be sufficient tension to prevent excessive sag between the carrying idlers.

Minimum tension to prevent slip Tm

At the point of slipping the relationship between T 1 and T2 is

T1

= eµθ

T2

Since T1 = Te + T2

1 T2 =

eµθ - 1

Te

1 The expression

eµθ - 1

:

is called the drive factor k. and the value of T 2 that will just prevent slip is referred to as the minimum to prevent slip T m and therefore

Tm = k x T e

Minimum tension to limit belt sag Ts

The tension required to limit sag is dependent on the combined mass of belt and load, the spacing of the carry idlers and the amount of sag that is permissable.

Ts = 9,8Sf x (B + Q) x l d

The value of the slack side tension must ensure that both conditions are met and therefore T 2 must be the larger of T m or T s.

Slope tension Th

The slope tension is the product of the belt weight and the vertical lift and has its maximum value at the highest point of the conveyor.

Th = 9,8B x H

Unit tension T

The maximum belt tension T 1 has as its reference width the full width of the belt. Usually this is converted to the tension per unit of belt width as this is the reference dimension for belt strengths.

T=

T1 W

Absorbed power

The amount of power required by the conveyor is by definition of power equal to the product of the force applied and the speed at which the conveyor belt travels. The force applied is the effective tension and hence the power required at the shaft of the drive pulley/s is

P = Te x S

STEP BY STEP EXAMPLE OF BELT TENSION CALCULATION

As an example of the application of the formulae the belt tensions for the following conveyor will be determined:

Belt width

900 mm

Co nveyo r Le ngt h

250 m

Lift

20 m


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Capacity

400 t/hr

Belt speed

1,4 m/s

Material conveyed

ROM coal

Drive

210 degree wrap. Lagged drive pulley.

Take-up

Gravity

Idler spacing

1,2 m

Idler roll diameter

127 mm

Page 8 of 33

1. Determine mass of the load per unit length

Q=

=

0,278

τ S

0,278 x 400 1,4

= 79,4 kg/m 2. Look up the value of the mass of moving parts in Table 10. From the idler roll diameter and the nature of the material conveyed the application is considered as medium duty. For a 900 mm wide belt the mass of moving parts from Table 10 is 55 kg/m 3. Calculate the corrected length and the length correction factor.

LC = L + 70 = 250 + 70 = 32 0 m C=

LC L

=

320 250

= 1, 28 4. Tension to move the empty belt.

TX = 9,8G x f X x LC = 9,8 x 55 x 0,022 x 320 = 3 794 N 5. Tension to move the load horizontally.

TX = 9,8Q x f Y x LC = 9,8 x 79,4 x 0,027 x 320 = 6 72 3 N 6. Tension to lift the load.

TZ = 9,8Q x H = 9,8 x 79,4 x 20 = 15562 N 7. No accessories are present and therefore the tension to overcome the resistance of accessories is zero. 8. Effective tension.

Te = T X + T Y + T Z + T U = 3794 + 6723 + 15562 + 0 = 26079 N 9. The absorbed power

P = Te x S = 26079 x 1,4 = 36511W 10. The slack side tension. Slack side tension to prevent slip. The drive factor for 210 degree wrap and lagged pulley with a gravity take-up, as given in Table 11, is 0,38.

Tm = k x T e = 0,38 x 36079 = 9 91 0 N

Slack side tension to limit sag to 2%. The sag factor for 2% sag is 6,3 and the estimated belt mass for a medium load and 900 mm belt width, as given in Table 8, is 11,1kg/m.

TS = 9,8Sf (B + Q) x l d = 9,8 x 6,3 x (11,1 + 79,4) x 1,2


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5000

300000

6300

377200

TABULATOR CALCULATIONS

For the purposes of

1.

Calculating vertical curves, or

2.

Determining belt tension for conveyors of undulating profile.

It is necessary to calculate the belt tensions at various points on the conveyor. Calculating the tension at any point along the conveyor.

The tabulation method described below is a convenient means of calculating the tensions at any point on the conveyor.

Blank copies of the "Conveyor Tabulation Sheets" are available from Dunlop Africa Industrial Products.

The following method is used to determine the tension at any point along the conveyor:

1.

Calculate the length correction factor.

2.

Look up the mass of moving parts in Table 10.

3. 4.

Calculate the mass of the load from the design capacity and the belt speed. Calculate the maximum effective tension under constant speed operation. This will always occur when all the non-declined sections of the conveyor are fully loaded and the declined sections empty.

5. 6. 7.

8. 9.

Determine the minimum value for the slack side tension under maximum load condition. Commencing from immediately behind the drive, label each pulley, intersection point and loading section. Start and end point of each of the load lengths should also be labelled. Determine the effective tension required to overcome the frictional and gravitational resistances for each of the segments of the conveyor by using formulae on page 4. The value of 12, determined in 5 above, is used to calculate the effective tension to overcome pulley friction. The effective tension at any point on the conveyor is the sum of the effective tensions of all preceeding segments. The total effective tension for the conveyor is the sum of the effective tensions for all segments. The tension at any point 'x' on the conveyor is made up of the effective tension at point 'x' plus the slope tension at point 'x'. Superimposed on this is the tension applied by the take-up system. The tension applied by the take-up is given by the worst case T2 value i.e. the value of T 2 which a.

prevents slip at the highest Te value and,

b.

limits sag between carry idlers.

It may be found that the value of T 2 obtained when the maximum effective tension has been calculated is different to that used in the calculations. If this is the case the new T 2 value is used to calculate tensions at each point.

Steps 7, 8 and 9 should be repeated for four load cases viz empty, fully loaded, non-declined sections loaded and declined sections loaded.

EXAMPLE

Belt width Conveyor length Lift Max capacity Belt speed Skirt length Material conveyed Lump size

1200 mm 500 m 45 m 4500 t/hr 3,5 m/s 3 m Iron Ore 100 mm

Bulk density

2,4 t/m3

Carry idler diameter

127 mm

Carry idler spacing

1,2 m

Return idler diameter

127 mm

Return idler spacing

3,6 m

Impact idler diameter

159 mm

Impact idler spacing Drive wrap

0,45 m 210 degree

Drive surface

Rubber lagged

Take-up type

Gravity

Step 1


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Page 25 of 33

Calculate the length correction factor

C=

L + 70 L 570

= =

500 1,14

Step 2

From Table 10 the mass of the moving parts for a 1200 mm wide conveyor of medium duty is 71 kg/m.

Step 3

Calculate the mass of the load

Q=

= =

0,278

τ s

0,278 x 4500 3,5 357,4 kg/m

Step 4

Calculate the maximum effective tension when the non-declined sections of the conveyor are all carrying load and the declined sections have no load. The total horizontal length of non-declined sections is 20 + 330 = 350 m.

The overall change in elevation on the non-declined sections is 70 in. Note that the actual length of the conveyor is used to calculate T

x

and

only the loaded length to calculate T y. The length correction factor is a constant and is used to convert the actual length to a corrected length. The friction factors are determined by the total conveyor length in all cases.

Effective tension to move the empty belt.

Tx = 9,8G x f x C x L = 9,8 x 71 x 0,020 x 1,14 x 500 = 7932N

Effective tension to move the load horizontally.

Ty = 9,8Q x f y C x L = 9,8 x 357,4 x 0,020 x 1,14 x 350 = 30745N

Effective tension to lift the load.

Tz = 9,8Q x H = 9,8 x 357,4 x 70 = 245176N

Effective tension to overcome skirtboard friction The inter-skirtboard width is assumed to be 2/3 of the belt width i.e. 0,8 m.

9,8f s x Q x L s

Tus =

=

S x b2 9,8 x 357,4 x 0,020 x 1,14 x 350 3,5 x 0,64

= 3050N

The total effective tension is the sum of the above four.

Te = Tx + Ty + Tz + Tus = 7932 + 30745 + 245176 + 3050 = 286903N


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Step 5

The minimum slack side tension to prevent slip is:

Tm = k x T e k = 0,38 from Table 11 and hence Tm = 0,38 x 286903 = 109023

The minimum slack side tension to prevent excessive belt sag is:

Ts = 9,8Sf x (B + Q) x I d = 9,8 x 6,3 x (14,8 + 357,4) x 1,2 = 27576N

From Table 8 the estimated belt mass is 14,8 kg/m

Since

Tm > T s

T2 = T m

i.e. T2 = 109023N

Step 6

The conveyor is labelled from A to 0 as shown on example sheets 1 to 4.

Step 7

Calculations of the effective tension for each segment (or run) is shown on Sheet 1 for the empty belt, Sheet 2 for the fully loaded belt, Sheet 3 for the case where only non-decline sections are loaded and Sheet 4 where only the decline sections are loaded.

Step 8

The accumulated effective tension column is the sum of the effective tensions of the current segment and all preceeding segments.

Step 9

The total effective tension for each load case is the value in the last row of the column titled 'Accumulated Effective Tension'.

For the empty belt

Te = 7665N

For the fully loaded belt

Te = 174188N

For all non-declines loaded Te = 283609N For only declines loaded

Te = -101755N

The reason for the difference between the effective tension determine step 4 and that on Sheet 3 is the more accurate figures used for mass of the moving parts on the tabulation sheets.

The tension at any point along the conveyor can now be determined, all load cases, by adding the effective tension at the point to the slope tension at the point and then adding the worst case T 2 value.

The highest T e value occurs when all non-declines are loaded. i.e. Te = 283609N

Based on this value

Tm = k x T e =

0,38 x 283609N

=

107771N


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Page 27 of 33

Since Ts, calculated in step 5, is less than T m

T2 = T m

i.e. T2 = 107771N

Thus, for example, the effective tension at run L - M takes the following values:

1. Empty Belt

4302N

2. Fully loaded

- 24577N

3. Non-declines loaded 6059N 4. Declines loaded

-26334N

From these it is determined that the tension at point M under the four cases, given by

Te + T2 + Th is

Empty belt

4302 + 107771 + 0 = 112073N

Fully loaded belt

-24577 + 107771 + 0 = 83194N

Non-declines loaded

6059 + 107771 + 0 = 113830N

Declines loaded

-26334 + 107771 + 0 = 81437N

CLIENT NAME Belt width

CONVEYOR EQUIPMENT NO. W

1200 mm

Conveyor length

L

500 m

Lift

H

45 m

Max capacity

τ

4500 t/hr

Belt speed

S

3,5 m/s

Skirt length

Ls

3 m

Material conveyed

Iron Ore

Lump size

100 mm

Bulk densiy Corrected length Correction factor

Lc C

Idler Data

Carry Return Impact

Trough Angle

35

0

35

degree

2,4 t/m3

Roll Diameter

127

127

159

mm

570 m

Spacing

1,2

3,6

0,45

m

17,1

22,9

kg/set

1,14

Rotating Parts Mass M 19,9

Friction Factors Rotating Parts f x

0,020

Load Friction f y

0,022

Skirt Friction f s Scraper Friction f c

Location

mm

O

0,65

Drive

Head

mm

O

0,60

HT Bend

-

mm

-

210°

Drive Surface

Lagged

Bare

Take-up Type

Gravity

Screw

Drive Factor k

Diameter 630

Drive & Take-up Angle of Wrap

Pulleys Head

Tail

500

mm

I

Take-up

500

mm

E

Take-up Bend

500

mm

D,F

LT Bend

450

mm

B

Tripper

-

mm

-

0,38


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Sinβ x W x E

R=

2.

4494 (tr - tc)

Minimum radius to prevent buckling

Sinβ x W x E

R=

3.

8988 (tr - 5,2)

Maximum allowable change of incline per idler to prevent overstress of belt edges

ø=

4.

Page 32 of 33

5,1 (tr - tc) x 1000 W x E x Sinβ

Maximum allowable change of incline per idler to prevent buckling

ø=

2,55 (tc - 5) x 1000 W x E x Sinβ

The curve must be designed with a radius at least large enough to satisfy conditions 1 and 2 and the idler spacing must ensure that conditions 3 and 4 are satisfied.

tr = Rated belt tension (kN/m) R = Radius of curvature (m) β = Troughing angle (degrees) W = Belt width (mm) E = Belt modulus (kN/m) tc = Belt tension at the curve (kN/m)

MAXIMUM INCLINE ANGLE

1.

Conventional smooth surface conveyor belts

2.

Ruftop package handling belts

3.

Ch ev ro n to p b el ts

4.

Boxes belts with flexible side walls

5.

Sandwich type conveyors

6.

El evator b el ts

GRAPH FOR ESTIMATING BELT LENGTH/ROLLED BELT DIAMETER

Belt length/rolled belt diameter

D = rolled belt diameter (mm) L = belt length (m) t = belt thickness (mm) d = core diameter (mm) N = number of coils on roll

Belt length:

π(D + d)N


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L=

Page 33 of 33

2

Rolled belt diameter:

or Assuming the length of belt is large and the thickness not abnormally small, then the core diameter can be neglected in approximate calculations.

Where d 0,3m for general stock belting and up to 0,5m for heavy rolls of belting, such as steelcord belting or very wide belts.

USEFUL DATA CONVERSION FACTORS

Imperial to metric

T o co nv er t fr om

To

M ul ti pl y by

in

mm 25,4

in

cm

2,54

ft

m

0,3048

in2

cm2


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Dunlop Conveyor Belt Design Manual

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