BELT CONVEYOR

Capacity and power calculationCapacity and power calculation

Component Component

Free body DiagramFree body Diagram

Standards Standards

S i i h i d ill i b l Some companies in the industry will require a belt conveyor system to meet a certain standard. These standards insure the safety of the conveyor but also effectiveness of it.

Different standards: DIN (German), ISO (World) , BS (UK) , CEMA / RMA (USA) AS (AUSTRALIA) JIS (J ) GOST (R i ) RMA (USA), AS (AUSTRALIA), JIS (Japan), GOST (Russia)

Standards will include handling and storage of belts strengths of Standards will include handling and storage of belts, strengths of belts, and dimension restrictions of each part in the system.

Shut off switches for operators and adequate safety shields and guards required to meet OSHA standards

BeltBelt

D fi iti (UNE 18 025)Definition (UNE 18 025): The width, expressed in mm. The quality of the cover (standard UNE 18 052).q y ( ) The number of plies. The quality of the fabric (standard UNE 18 052). The thickness of the top cover (tenths of mm). The thickness of the bottom cover (tenths of mm).

The length of the belt (metres) The length of the belt (metres).

Belt Belt

Textile belts or smooth textiles

BeltBelt

Belt Belt

D b k f th t til Drawback of smooth textile belt: Grade limit : 18o - 20o Grade limit : 18o 20o

Different solutions: Profile belts: Herringbone profile. Nasta, Nappula, Ripa and

Pyramid profile.Pyramid profile. Grip Top profile. Ripro profile.

U l t d V l t fil U-cleats and V-cleats profiles. Corrugated edge belt.

Driving pulleyDriving pulley

TENSIONTENSION

The tension varies along the belt length. Depends on: Belt conveyor arrangement. The number and arrangement of the drive pulleys. The drive and brake features The drive and brake features. The type and tension devices arrangement. Operation phase (start-up, normal operation, braking, etc.).

TENSIONTENSION

One drive pulleyOne drive pulley

Most common situation. Operation conditions: Peripheral forces applied to the drive pulley have to be

transmitted to the belt b friction witho t slippagetransmitted to the belt by friction without slippage. The applied tension to the belt has to be adequate to avoid

an important sag (between two pulleys).

TENSIONTENSION

Euler-Eytelwein (without slip) equation:

Pulley diameterPulley diameter

Component weightComponent weight

MOBILE COMPONENT WEIGHT PER UNIT LENGTH

Resistant movementResistant movement

Principal resistantPrincipal resistant

T i i t d t th l d idl ll d t f i ti i th Turning resistance due to the load idlers rollers, due to friction in the bearings and joints in rollers.

Belt friction resistance due to the rolling of the belt over the idlers llrollers.

Secondary ResistantSecondary Resistant

Secondary ResistantSecondary Resistant

Secondary ResistantSecondary Resistant

LENGTH CORRECTION FACTORLENGTH CORRECTION FACTOR

Shorter belts need more power to overcome friction resistances than longer belt conveyors.

Special principal resistanceSpecial principal resistance

Special principal resistanceSpecial principal resistance

R i t d t f i ti ith f d i h t id ll Resistance due to friction with feed-in chute sidewalls, or with the longitudinal guide rails, when they take place along the total belt length:g g

Special secondary resistancesSpecial secondary resistances

Resistance due to slopes

POWER OF THE DRIVE PULLEYPOWER OF THE DRIVE PULLEY

For powered belts:For powered belts:

TRANSPORT CAPACITYTRANSPORT CAPACITY

TRANSPORT CAPACITYTRANSPORT CAPACITY

TRANSPORT CAPACITYTRANSPORT CAPACITY

U if t i l i ( l l ill d t ) d Uniform material size (cereals, granules or milled stones) do not influence belt width.

Non classified materials (materials obtained in quarries or Non classified materials (materials obtained in quarries or mines) influence on belt width: Maximum material size.

Fi d i Fine and coarse-grain percentage. It may occur that for little capacities the belt width is big

not economic Belt width as a function of the maximum grain size:

TRANSPORT CAPACITYTRANSPORT CAPACITY

Th b lt d h t b bi ibl th t idth i h t The belt speed has to be as big as possible so that width is short. Speed depends on material properties:

Fluidity. Dust risk.y Abrasion. Belt cut risk. Friable. Material split risk. Size Great impacts on the belt take place for big sizes and heavy ones Size. Great impacts on the belt take place for big sizes and heavy ones,

thus weakening the belt.

TRANSPORT CAPACITYTRANSPORT CAPACITY

EXAMPLE TRANSPORT CAPACITYEXAMPLE TRANSPORT CAPACITY

SOLUTIONSOLUTION

We select B = 1000 mm

Specify the Resultant load of the pulleySpecify the Resultant load of the pulley

Belt tension and frictionBelt tension and friction

nomenclaturenomenclature

Friction coefficientFriction coefficient

Pulley diameterPulley diameter

exampleexample

Example, from friction coefficientExample, from friction coefficient

Example from wrap angleExample from wrap angle

Bearing life and balancingBearing life and balancing

Discussion