Belt conveyor pulley

This invention relates to a conveyor pulley and more particularly to a roller for the pulley which is made from a suitably bonded particulate material such as silica sand.

FIELD OF THE INVENTION 
This invention relates to pulleys such as head, tail or idler pulleys for 
use in a belt conveyor systems. 
BACKGROUND TO THE INVENTION 
Belt conveyor pulleys are generally made from or at least their running 
surfaces are faced with metal. Most belt conveyors which are used in the 
mineral processing industry operate in harsh environmental conditions and 
are subject to corrosion and abrasive wear. Corrosion of conveyor pulleys 
is a particularly serious problem in the fertilizer industry where the 
conveyors transport highly oxidic and acidic chemicals. Yet further 
problems with conventional metal conveyor pulleys is that in some 
applications they become magnetised and/or charged with static electricity 
to a point where sparking may result which could be extremely dangerous in 
certain environments such as in mines. 
OBJECT OF THE INVENTION 
It is the object of this invention to provide conveyor pulley in which the 
above disadvantages with metal pulleys are eliminated. 
SUMMARY OF THE INVENTION 
A conveyor pulley according to the invention includes a roller which is 
made from a suitably bonded non-magnetic particulate material, and a shaft 
which is located in the roller, on its axis of rotation to project from 
each end of the roller. 
In one form of the invention the shaft is moulded into the roller material. 
Conveniently the portion of the shaft which is located in the roller is 
squared or has some other non-circular shape or includes outwardly 
projecting formations which key into the roller material to prevent 
relative rotation between the roller and shaft. 
In another form of the invention the roller includes an axial bore in which 
the shaft is rotatably located and recesses in its ends with the pulley 
including bearings which are located in the roller recesses and in which 
the shaft is journalled for rotation. 
Further according to the invention the roller includes a plurality of mass 
reducing bores which extend over the length of the roller between the 
shaft axis and the outer surface of the roller in a balanced relationship 
about the roller axis. 
Still further according to the invention the roller includes a plurality of 
reinforcing rods which extend over a substantial proportion of the length 
of the roller between the shaft axis and the outer surface of the roller 
in a balanced relationship about the roller axis. 
A conveyor pulley roller according to the invention is made from a 
non-magnetic particulate material which is bonded by a suitable bonding 
material. 
A conveyor pulley roller according to the invention is sleeved by a sleeve 
of particulate material which is bonded by a suitable bonding material. 
Preferably the particulate material is a washed silica sand. 
The bonding material may be an expoxy resin, polyurethane or like material. 
The conveyor pulley roller could, additionally, be made from a fired 
ceramic clay.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
The pulley rollers 10 of the invention are moulded from a mixture of washed 
silica sand and epoxy resin. The sand/epoxy mix which is used in moulding 
a particular roller will depend on the compressive strength required of 
the roller material. For example, in using a 7 sand to 1 epoxy mix and a 
5 sand to 1 epoxy mix the compressive strength of 150 MM cubes of the 
material 25 days after moulding were respectively 21.0 and 53.5 MPa 
respectively. The bulk of the sand used in the mix was material screw 
overflow grade with about 15% of the material being of a less coarse grade 
and approximately 0.05% of fine material. 
The FIGS. 1 and 2 embodiment of the conveyor pulley roller is shown to 
include a shaft bore 12 which extends through the roller on its axis of 
rotation and a recess 14 in each of its ends. In assembling the conveyor 
pulley of the invention a bearing seat 16 which is made from a suitably 
robust resilient plastics material is press fitted onto the base of the 
recesses 14 as shown in FIG. 2. A shaft 18, which is conveniently made 
from a non-corrosive metal such as stainless steel, which has its ends 
shaped as shown in FIG. 2, is then located in the bore 12 of the roller 
with lands 20 on the shaft in register with the outer faces of the bases 
of the seals 16. Bearings 22 are then pressed over the shaft and into the 
seats 16 as shown in FIG. 2. Circlips 24 are then engaged in grooves 26 in 
the shaft 18 to lock the bearings 22 and the shaft 18 in the roller 10. A 
suitable dust seal 28 is then pressed into the forward part of the recess 
to prevent the ingress of fines into the bearings 22. Preferably, the 
internal cavities in the seals 28 and the bearings 22 are greased packed 
prior to the location of the seals 28 in the roller recesses. The seals 28 
may frictionally be held in place but may conveniently also be held in 
place by a suitable adhesive. 
It is to be noted that the bearing and seal system described above is only 
one embodiment of many which may be used with the conveyor pulley of the 
invention. 
The pulley shown in FIG. 3 of the drawings is intended for use as a drive 
or tail pulley in a conveyor system and in this embodiment the shaft 18 is 
embedded in the. material of the roller 10 with the portion 30 of its 
length which is embedded in the roller material being squared as shown in 
the drawing or provided with other suitable radially projecting formations 
which will key into the roller material to prevent relative rotation of 
the roller and the shaft 18 in use. 
Because the FIG. 3 pulleys are generally of a fairly large diameter they 
may conveniently include mass reducing bores 32 which are located around 
the axis of the shaft 18 in a configuration which will maintain the 
rotational balance of the rollers 10 about the axis of the shafts 18 in 
use. 
In another variation of the roller of the invention, where great strength 
is required from the roller, reinforcing rods made from metal, glass fibre 
or the like could be embedded in the roller material to extend over a 
substantial proportion of the length of the roller in a balancing pattern 
around the roller axis much as are the bores 32 of the FIG. 3 embodiment. 
Another means of reinforcing the roller material on any of the pulleys of 
the invention, would be to include in the roller material mix, prior to 
moulding, chopped strands of fibreglass or other suitably strong stranded 
material. 
The invention is not limited to the precise details as herein described and 
for example the particulate material from which the rollers are made need 
not necessarily be sand but could be any suitable particulate material. 
Such a material could for example be a fired ceramic clay. 
From the above it will be apparent that the pulleys of the invention are 
entirely corrosion resistant, are non-magnetic and their slightly 
roughened outer surfaces, particularly of the drive pulleys, provide the 
pulleys with excellent traction characteristics.