Conveyor Belts

Definition

A mechanical apparatus consisting moving belt that transports material from one place to another.

Types of conveyor belt system

1) Troughed belt conveyor

2) Flat belt conveyor

3) Pipe belt conveyor

• Belt forms a trough on the carrying side while running over idler rollers

• in set of 5 rolls, 3 rolls or 2 rolls.

• The troughing angle adopted are: 15°, 20° , 25° , 30° , 35° , 40° , 45°.

Troughed belt conveyor

Flat belt conveyor

• Belt runs flat on the carrying side over straight roller type idler or a set of idlers.

• Suitable for lower capacity, low speed requirement .

Pipe belts

• Used where bulk materials must be conveyed along horizontal and vertical curves in confined spaces

• Used where spillage must be avoided.

• The belt can negotiate tight horizontal and vertical curves.

Belts

Conveyor belts

consists of 3 elements:

1)Top cover

2)Carcass

3)Bottom cover

Types of conveyor belts

1)Steel cord belt

2)Textile belts

Steel cord belt

1)Consists of top cover layer

2)Adhesive component

3)carcass(steel cord mesh)

4)bottom cover layer

Steel cord belt

1)They ensure maximum conveying performance under grueling stress conditions.

2)High tensile strength.

3)Excellent impact resistance.

Textile belts

1)Various cover stock properties according to applications.

2)Low price .

3)Easy maintenance.

Types of textile belts

1)Temperature resistance belts

2)Oil & grease resistance belts

3)Slit protection belts

4)Dirt repellent cover belts

Belt designation

1. Driving pulley2. Tail roller at end of installation3. Slider bed4. Carrying rollers on the carrying side5. Snub roller6. Tail roller7. Tension roller8. Carrying roller on the return side

Belt nomenclature

Steel cord belt conveyor 2000 m DIN 22131 AB 1200 St 1600 7T/5 X

2000 m Length DIN 22131 Applicable standard/norm AB Manufacturer's acronym 1200 Belt width in mm St Carcass material (steel cords) 1600 Belt's minimum breaking strength in N/mm *) 7 Top cover thickness in mm T Textile reinforcement (in top cover) **) 5 Bottom cover thickness in mm X Rubber Cover grade

Textile belt conveyorE.G 1000 m DIN 22102 AB 1000 EP 630/4 6/2 Y

1000 m Length

DIN 22102 Applicable standard/norm

AB Manufacturer's acronym

1000 Belt width in mm

EP Carcass material (polyester warp / polyamide weft)

630 Belt's minimum breaking strength in N/mm

4 Number of plies

6 Top cover thickness in mm

2 Bottom cover thickness in mm

Y Rubber cover grade

Failures in belt conveyor system

• Drive unit failure

• Pulley failure

• Idlers and belts failure

Drive unit failure

• Drive unit consist of electric motor, damping coupling, two or three stage gear-box and coupling that connect output shaft with pulley

• Failures occurs mainly in Pulleys and gear box

Actual Pulley

Failed pulley

Pulley failure

Idler & belt failure

• Due to over load Side idler may fail.

• Due to foreign Pointed bodies belt may cut along its length.

• Bearings in the idlers may fail

Belt conveyor troubleshooting

Problem Cause solution1) Conveyor belt runs to one side at a particular point on the conveyor.

One or more idlers not at right angles to longitudinalcenterline of belt.

Build up of material on idlers.

Sticking idlers.

Advance the end of idler to which the belt has shifted in the direction of belt travel.

Improve maintenance. Install scrapers.

Replace or free idler

Problem Cause Solution

2) Excessive wear on bottom side of belt.

Slippage between belt and drive pulley or pulleys. (Cont.)

Sticking troughing idlers.

Material ground between pulley and belt.

Lag drive pulleys, renew worn-out lagging.

Increase arc of contact drive pulley with snub pulley or use tandem drive. Replace or free stuck idlers. Install scrapers in front of tail pulley or return belt.

Problem Cause Solution

3) Excessive wear on carrying side of belt.

Dirt, frozen or misaligned return idlers.

Excessive sag between troughing idlers causing load to move and shift on belt as it passes over idlers.

Install belt-cleaning plows at head end and tail end.

Clean, repair and align return idlers. Increase belt tension if too low.

Reduce idler spacing.

Use rubber skirt material.

Avoid use of old belting.

Problem Cause Solution

4) Short breaks in carcass of belt parallel to edge and star breaks in carcass.

Impact of lumps falling on belt at loading station.

Material trapped between belt and pulley.

Use impact idlers.

Install plows or scrapers ahead of pulley.

Problem Cause Solution

5) Belt running off at tail pulley.

Build up of material on return idlers.

Return rollers out of line.

Unequal loading.

Remove material provide better housekeeping.

Adjust at right angle to frame.

Adjust loading chute to properly center the load.

Preventive maintenance of belt conveyor system

Daily preventive maintenance1) Check operation of conveyor controls. Ensure

that all "STOP" pushbuttons operate properly. Also ensure that all limit switches function properly

2) Clean any accumulation of dust

3) Never touch a moving belt or rotating part.

4) Keep large lumps of material off belts

5)Note and mark “frozen” or damaged idlers for repair or replacement.

Daily preventive maintenance

6) Check scrapers and plows for proper operation.

7)Watch for material to build up on decking or floor under idlers or pulleys. This is especially important at training idlers.

8)Prevent large lumps from dropping onto unprotected belt.

 

Weekly preventive maintenance1)(Conveyor Drive) Check reducer (gearbox) oil

level, Check reducer for oil leaks, Inspect drive coupling , Check oil level in backstop and inspect for leaks , Ensure all safety guards for drive are in place and in good condition. never touch a moving belt or rotating part.

 

2)(Safety Switches) Inspect cables for correct tension, Ensure flags are free from material build up. do not touch loose wires.

 

Weekly preventive maintenance

3)Head pulley) Inspect belt cleaners for worn or missing blades, Inspect belt cleaners for cleanliness of frames and blades , Check belt cleaner tension according to manufacturers recommendation , Ensure belt is cantered on pulley.

 4)(Tail pulley) Ensure belt is centered on pulley, check V-plow blade for wear, Check V-plow mounting , Check V-plow tension

How to avoid spillage over conveyor?

Spillage over the conveyor occurs mainly at three different areas:

1)Loading point containment

2)Preventing the escape of material from the run of conveyor

3)Managing the discharge of the materials being conveyed.

Use of pipe conveyor belt

Scrapper

1)Scrapper cleans belt after belt discharges material from it.

2)Material carry back and reduce spillage.

3)Avoid material built up on snub pulley and return idler.

Skirt rubber

1)Prevents material falling down.

2)Avoids spreading dust in atmosphere.

3)It also serves purpose of guarding.

Methods of conveyor belt joining

Belt splicing

Definition: Conveyer belt

splicing is the process of joining together two pieces of conveyer belt.

Mechanical splicing It involves use

of several types of metal fasteners

It is a quick and versatile method used in dirty and confined environments

Relatively inexpensive

Vulcanization

1)Vulcanization creates a splice by using heat and/or chemicals.

2)Requires special tools, expertise, and a clean, temperature- and moisture-controlled environment.

3)Splice is smoother and typically more durable than a mechanical splice

Types of vulcanization

Hot vulcanization Cold vulcanization

1)splices by using heat and pressure through use of a vulcanizing press.

1)Use of chemicals that bond two pieces of belt.

Safety

How to avoid accidents in belt conveyor?

Guarding

1) Each workplace must be examined at least once in each shift for conditions which may adversely affect safety.

2) Prompt action must be initiated to correct hazardous conditions.

3) Moving machine parts must be guarded to protect persons from contacting them.

4) Guards must be securely in place while machinery is being operated .

5) New employees must be indoctrinated in safety rules and safe work procedures

Best practice

1)Maintenance should not be performed unless the power is off and machinery components are blocked against hazardous motion.

2) Moving machine parts should be guarded to protect persons from contact that could cause injury.

M3)Maintenance should not be performed unless the power is off and machinery components are blocked against motion. 4)Visible or audible warnings should be provided before conveyor start-up when the entire length of the conveyor is not visible from the starting switch. 5)Machine operators should take measures to assure all personnel are trained in safe work procedures.

Guard comparison

Bad guard Better guard

Bad guard Better guard

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