On Belt Conveyors By Neil Kinder & Charles Pratt
Equipment Characteristics Irrespective of the material, the same type of conveyors are used, all using the same technology, operating principles, operating parameters and safety measures. Each has equally its own challenges in the transportation of material from point A to point B. Using conveyors or bucket elevators.
Basic Technical Expectations To provide a clean and safe work site free of spillage from conveyors. To achieve rated service life from conveyor belts. To achieve rated service life from conveyor hardware. Idlers / Pulleys To limit outages during production caused by conveyor problems.
Same Objectives Improve productivity. Improve reliability. Operate safely without incidents. Be cost effective. Be environmentally responsible.
What has changed? Safety is #1priority. Risk of silicosis. Be environmentally responsible. Operate with unskilled labor and limited access to skilled labor. Ageing Workforce.
Safety Is Now A Measure Of Conveyor Performance. The measure of success in all production operations should use safety as its primary rule of measure. There are a number of reasons for running a safe operation. 1. Good business practice. 2. Maintains high staff morale. 3. Helps to retain the best highly skilled. Especially in a period of skill shortage. 4. Let alone it s against the law and there are some tough penalties for serious breaches.
Identifying the Risk
Conveyor Maintenance Includes proper not only care of the belt itself but includes care and maintenance of the frame and conveyor hardware. More importantly it includes eliminating the risk of injury and death to personnel operating in the vicinity of the live conveyor.
Types of Conveyors
Each Conveyor Type Has Its Own Inherent High Risk Potential Belt Conveyor Fire Bucket Elevator Explosion
Belt Tracking is considered a route cause of many problems leading to serious damage. Belt Conveyor Structural Damage. Belt Damage. Spillage. Dust Leakage. Entanglement of operating personnel. Fire
Belt Conveyor Inspection. Good Housekeeping - Critical Structural Damage. Missing or Loose or Damaged Rollers. Belt Damage / Splice Damage. Belt Mistracking.
Belt / Chain Tracking is considered a route cause of many problems leading to serious damage or risk exposure. Bucket Elevator Structural Damage. Belt / Splice Damage. Or Chain Damage. Bucket Damage. Fire. Entanglement of operating personnel. Explosion.
Bucket Elevator Inspection. Good Housekeeping Critical Check for Structural Damage Elevator Casing Looseness or Corrosion Missing or Loose or Damaged Buckets. Chain Stretch or Damage. Belt Damage / Splice Damage. Belt Mistracking.
Belt Tracking Why is it so important that the belt runs TRUE? It s a bit like a laden truck on a freeway. The situation is worse when the truck is travelling at high speed without proper steering.
Belt Tracking Safety Efficiency Reliability The goal in achieving proper and consistent belt tracking is to ensure safe, consistent, trouble-free, economical conveyor system operation in short, to be able to walk away from the system and not worry about its operation for reasonable periods of time.
Worsley Cable Belt 52 Kl Overland Conveyor at Worsley W.A.
Belt Tracking Route Cause of Spillage. Understanding that belt mis-tracking is the route cause of spillage, reduced belt life and the cause of many serious accidents, some resulting in death of workers. Or the loss of limbs. Don t accept that conveyors will not track true under all operating conditions and work towards rectifying the faults. Use the signs of spillage and belt damage during inspection find the cause of belt misalignment. In the case of elevators - belt and or bucket damage.
COMMON CAUSES OF BELT MISALIGNMENT. Sunken or not level foundations. The driving and idler pulleys not normal to the conveyor centreline and not parallel with each other. Seized or out of round rollers. Transverse forces applied to the belt by items such as over tight angled belt scrapers. Material build up on the pulleys, belt or rollers. Damaged, twisted and or missing conveyor idler frames. Crosswinds. Uneven placement of load on the belt or the belt being loaded off centre. Uneven skirting pressure.
What to look for. Poor workmanship with belt splicing / slitting / ends squaring. This includes localised edge repairs with associated tension differences. Transition idlers not installed or unevenly adjusted. Poor quality pulley manufacture with the diameter not symmetrical to the centreline of the belt. (Pulley faces may be worn.) Excessive tensioning of the belt preventing all of the idlers from helping to direct the belt. Under tensioning of the belt which restricts the pulleys from controlling the belt. This also applies to all pulleys including take-ups. Uneven or misaligned pulley take-up carriage forces. The belt hotter on one side than the other, for example near a furnace.
You will get dirty. Worn pulley faces, pulley lagging unevenly worn or pulley shaft locking elements worn. Trough and return idlers not installed at right angles to the axial centreline and therefore the belt not making proper contact with the rollers. Trough idlers installed back the front with the lead roller not leading. Offset trough idlers being used on reversing conveyors rather than in-line idlers being used. Out of round or seized rollers giving the belt contact forces asymmetric to the centreline. Poor belt quality with the weave / fabric asymmetric to the centreline. Incorrect belt storage which has caused the belt to warp or bow. Belting of a different manufacture in the same length.
You may need a torch. Traveling trippers and shuttle not running true. One side of the belt running wet. Extraneous articles fouling the conveyor belt. The belt too stiff for the idler width or trough angle, therefore not allowing the idlers to direct the belt. Return idler spacing too great to direct the belt. Existing self-aligning idlers worn out, seized, or locked into position. Existing self-aligning idlers installed incorrectly or in wrong location. Mechanical fasteners not installed square. Conveyor rollers of various diameters installed.
Bucket Elevators
Elevator Check List 1.Visually check motor 2.Grease motor bearings 3.Check gearbox oil 4.Change gearbox oil 5.Visually check gearbox seals 6.Check gearbox mounting 7.Visually check pulleys/sprockets 8.Check pulleys/sprockets mounting 9.Visually check belts/chain 10.Check belts/chain tension 11.Check backstop mounting 12.Visually check head and boot bearings 13.Grease head and boot bearings 14.Check/adjust discharge throat wiper 15.Check head pulley lagging 16.Visually check belting 17.Check belt joiners 18.Check belt tracking head and boot 19.Check belt tension 20.Check buckets and mounting 21.Check bucket bolts 22.Visually check elevator casing
Common Elevator Problems Premature belt wear Belt slipping on head pulley Check the belt tension is adequate. Check boot is not being overfed, thereby putting extra drive load on the head pulley. Check the head pulley surface condition to see if needs re lagging. Check there isn't a build-up of "hardened product in the boot. Abrasive wear caused by excess product in boot. Control flow of product into boot. If product is abrasive, feed on up leg ONLY. Buckets pull loose from belt Obstruction in boot Check and clean out residual material in boot. Bucket bolts not tight Check bucket bolt tightness at regular intervals. Ensure nuts have some locking mechanism.
Conveyor or Bucket Elevator Belt running off-centre Product build up on pulleys Scrape pulleys and belt clean. If boot pulley is a plain drum type, change for slatted cone type. Check that product isn't falling back from incorrect discharging at head. Poor belt joint whatever belt joining system is used, the joint must be square. Rejoin according to bucket elevator manufacturer's recommendation. Belt not tracking around head pulley "Jack" bearing/s as required and shim to hold in place. To track belt, RAISE the bearing on the side the belt is running towards. Belt not tracking around boot pulley Adjust takeup and lock into position. To track belt, LOWER the bearing on the side the belt is running.
The fundamentals are the same. Each Conveyor Type Has Its Own Inherent High Risk Potential Belt Conveyor Fire Bucket Elevator Explosion
Or the worst case scenario.
Safety Is Now A Measure Of Conveyor Performance.