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Chain speed, normally calculated in feet or metres per minute, is a critical consideration in determining the

conveyor capacity. It is in considering this parameter that conveyor chain pitch and conveyor chain drive and

idler sprocket can be determined. fig. 5.1 illustrates the relationship between speed, chain pitch and sprocket

size. The maimum recommended conveyor will be up to !" metres #1"" feet$%minute. Chain speed is a critical

influence in smooth conveyor chain operation and etended service life. Too high speeds can create the

condition of pulsing or surging which can seriously compromise conveyor chain performance.

The chain speed, the distance travelled by the chain in a given unit of time, is a fundamental factor in

determining the conveyor capacity. It is from this parametr that chain pitch and the diameter of the driven

wheels is derived. fig. 5.1 illustrates this relationship.

& ' chain pitch (mm)

T ' number of teeth

n ' revolution per minute of the wheel (rpm)

5.1Intermittent contact between chain and track guides creating variations in friction factor and pulsing. This

can be controlled by reducing chain speed.

5.2*ow Conveyor chain speed can create a similar effect. Typically speed below ! metres #1" feet$%minute.5.3+cessive friction due to the condition of the chain and wear strips. This could be the result of

contaminants or general wear in mating components within the system.

5.4The polygonal effect in considering the relationship of the chain and sprockets #see fig 5.$.This can be

particularly prevalent on long pitch chains and small diameter sprockets. The designer must take care to

ensure compatibility between chain pitch and sprocket diameter to establish smooth chordal action.

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n ' rpm

T ' number of teeth of the wheel

- ' pitch radius of the wheel (mm)

-r ' range of variation of the polygonal effect (mm)

5.5/neven loading on the conveyor will also influence the condition. In some case this is unavoidable, but

must therefore be taken into account in the process of chain selection to ensure correct parameters are

established.

5.60lip tick0 will be seen on roller conveyors running at slow speed. This is often the result of over

lubrication between roller and wear strip. The friction factor is reduced to the point where friction is greater than

bush and roller bore. The roller stops turning. The intermittent condition of roller rotation and skid causes the

chain speed to fluctuate. This condition is slip stick. It tends to occur on lighter conveyors since heavier loads

will tend to increase bearing pressure and thus friction which will encourage roller rotation. This can often be a

route to a solution if this condition is encountered.

5.72ery long conveyors which become difficult to tension or are sub3ect to varying operational conditions canalso be sub3ect to pulsing or surging. The designer needs to make additional considerations for conveyors over

4" metres#5" feet$.

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+ste tipo de transportador tambi6n denominado 7ulk 8lo tiene usos particulares en el transportede materias primas alimentarias sensibles a las condiciones ambientales.

+l transportador 9-edler9 #8igura. 5"$ consta de una ca3a rectangular :ue alo3a la cadena deeslabones anchos y planos, acanalados transversalmente; est< compuesto de &untos descarga; #1y $; Tambor propulsor; #!$; =daptador a canal de tolva o silo #$; &alanca reguladora de descarga

#>$

Figura. 50 Transportador "Redler" (horizontal)

+l tramo inferior se mueve por el fondo de la ca3a y es el ?rgano transportador, mientras :ue elsuperior marcha en retorno sobre rieles su3eto a las paredes de la ca3a y, por encima del material@una rueda dentada hace de transmisi?n del movimiento; en el otro etremo el rodillo sirve como

?rgano tensor.

*a cadena, al pasar por el fondo de la ca3a, arrastra la capa de material alimentario comprendidaentre las piezas transversales, y esta capa le transmite el movimiento al material situado encima.

+l material y la cadena forman asA una corriente Bnica de velocidad uniforme, la altura m

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Fig. 51 Transportador "Redler" (erti!al horizontal).

+l tramo descendente de la misma cadena cuelga libre en el interior de la ca3a vertical, separadodel canal elevador propiamente dicho por una pared intermedia y va a arrollarse en el rodillo #>$, *acurvatura #E$, permite suprimir el ?rgano tensor igualando cual:uier alargamiento posible de lacadena en su caAda libre.

Tanto los elevadores de cangilones, como los 9-edler9, sirven principalmente para materiales detipo alimenticio desmenuzado y fino, no pega3oso.

*a capacidad de los transportadores se determina por la f?rmula@

# $ 3600 % & % h % % % ' (10)

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Fonde@

7 ' ancho de la aleta en m;

h ' altura de la aleta en m;

v ' velocidad de la cadena en m%seg;

' densidad aparente del material en t%m !;

G ' coeficiente #",E ",H para transporte horizontal$ y #",5",4 para transporte vertical$.