FIELD OF THE INVENTION
The present invention relates to improved configuration of the bottom idler roller for belt
conveyor adapted for enhanced life of roller. More particularly, the invention is directed to
an improved corrosion resistant surface treatment with rubber lagging apart from selective
variable diameter configuration of idler roller, especially for conveyors for handling of
quenched coke in coke oven plant. The present invention provides for improved
configuration of the idler roller on one hand helps reducing the frequency of replacement
and downtime for maintenance, on the other hand ensure running of the conveyor belt at
the central portion of idler so that the spillage of carried material is avoided enhancing belt
life. The idler rollers for the conveyors in coke oven plant thus reduce down time and
maintenance time and cost and thus improving the productivity in coke oven plant in
terms of uninterrupted handling of quenched coke.
BACKGROUND ART
The conventional bottom idler rollers for belt conveyors for material handling in continuous
operation, are typically fabricated from steel pipe of selective gauge mounted over an
axle/spindle having bearing housing of suitable size such that the pipe rotates freely with
the movement of conveyor belt while the spindle mounted on the brackets on the
supporting stringer frame on both sides remain stationary. Particularly, when the handling
of quenched coke in coke oven plant is considered, such idler rollers of the conveyor belt,
the middle portion of the pipe gets damaged at a faster rate reducing the life of bottom
idler rollers. The presence of phenolic water that is acidic in nature and its contact with the
roller surface as well as high abrasive nature of coke breeze causes the faster wear and
damage to the idlers requiring frequent replacement. Normally, replacement of the idlers
in conventional configuration requires more time and manpower and resultant loss of
productivity in terms of interruption of material handling. Thus the conventional
configuration of the bottom idlers of conveyor belt in the coke oven plants carrying the
quenched coke suffered from reduced life due to the following main reasons:

a. The wet and sticky coke granules deposited in the middle portion of carrying side of
the conveyor belt have substantial abrasive effect on the middle portion of bottom
rollers and cause damage to the middle portion of pipe.
b. The water used for quenching carried along with quenched coke being conveyed
contains acidic phenol causing corrosion of roller surface.
There has thus been a persistent need to developing an improved configuration of idler
rollers for the conveyors used to carry materials, especially quenched coke in coke oven
plant of steel plants such that the surface corrosion due to acidic phenol effluent after
quenching or abrasive wear due to wet and sticky granules of coke on middle part of
conveyor surfaces. The invention is directed to enhance the idler roller life and avoids
frequent replacement thus improving productivity by reducing the frequency of idler
replacement and related down time and thereby ensuring uninterrupted material handling
and production.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to developing an improved
configuration of bottom idler rollers for belt conveyors, especially for those used to carry
quenched coke in coke oven plants, to reduce the wear and damage of roller surface,
enhancing its operational life and improving productivity of plant by reducing frequency of
downtime and consequent replacement time and costs.
A further object of the present invention is directed to developing an improved
configuration of bottom idler rollers such that the conveyor belt running in the central
portion of idler resulting in reduced spillage of quenched coke material carried, enhancing
the belt life.
Another object of the present invention is directed to developing an improved
configuration of bottom idler rollers that would facilitate quick replacement of roller with
less manpower.
A still further object of the present invention is directed to use selective diameter of pipes
for fabricating the bottom idler roller such that a recess is maintained to relieving the

excess abrasive wear of the middle part of the pipe from adhering abrasive wet and sticky
coke fragments on conveyor.
A still further object of the present invention is directed to developing an improved
configuration wherein the pipes used in the idler is coated with a phenolic corrosion
resistant rubber coating.
A still further object of the present invention is directed to developing an improved
configuration of the bottom idler roller is made easy to install/replace and is automatic
self-centering type on return side such as to carry material centrally without spillage,
avoiding interruption of handling of quenched coke for longer operation time.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a bottom idler/roller for belt
conveyor adapted for handling wet & sticky material and/or with corrosive content such as
handling of quenched coal comprising:
tubular steel pipe adapted to be mounted over an axle/ spindle having bearing housing of
suitable size and adapted such as to favour rotation freely with the movement of the
conveyor when installed with respect to said stationary spindle mounted on brackets
comprising:
said tubular pipe having a middle portion of smaller diameter with the ends thereof of
greater diameter adapted to favour abrasive material, in the middle, pass without
touching the idler/roller surface.

Another aspect wherein said tubular pipe having a diameter in the middle of 88.9 mm to
98.9 mm and at the end of 152.4 mm to 182.4 mm.
A still further aspect of the present invention is directed to a bottom idler/roller for belt
conveyor wherein the middle portion of smaller diameter defines a space /gap which is
selectively provided based on the loading of the empty belt.
A still further aspect of the present invention is directed to a bottom idler/roller for belt
conveyor wherein the tubular pipe is obtained of as a single integral piece or plurality of
concentric pipes of stated dimensions with said smaller diameter pipe in the middle.
A still further aspect of the present invention is directed to a bottom idler/roller for belt
conveyor comprising rubber lagging provided on the idler/roller pipe for safe guarding the
steel against corrosion from phenolic water.
According to yet another aspect of the present invention directed to a conveyor system
adapted for handling wet & sticky material and/or with corrosive content such as handling
of quenched coal comprising
bottom idler /roller mounted over axle /spindle having bearing housing of suitable size
such that the idler/roller rotates freely with the movement of conveyor belt while spindle
mounted on the brackets on both sides of the stringer frame remains stationary.
The present invention and its objects and advantages are described in greater details with
reference to the accompanying non-limiting illustrative drawing.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the schematic illustration of an embodiment of the bottom idler roller for belt
conveyor according to the present invention, adapted to prevent wear/corrosion and
ensure enhanced bottom idler/roller life.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURE
The present invention is directed to developing an improved configuration of the bottom
idler roller, particularly for carrying quenched coke in the coke oven plant. The disposition
of the bottom idlers on return path of the empty conveyor belt in the arrangement of
handling of quenched coke in the coke oven plant are susceptible to corrosion by phenol
water having acidic characteristic carried along quenched coke and also the wet and sticky
hard coke particles/small fragments attached to the carrying side of the loaded conveyor
causes abrasive wear at the middle portion of the pipe of the bottom idler/rollers in
contact with the conveyor in the existing configuration of the handling system For
quenched coke in the coke quenching plant.
Attention is now invited to accompanying Figure 1 that illustrates an embodiment of the
bottom idler/roller according to the present invention directed to an improved
configuration adapted to reduce surface wear/corrosion to enhance the idler life as well, as
provide ease of servicing/replacement. It is a point of distinguishing inventive intent that
once the hard coke particle adhering to the conveyor surface has been identified to be the
principal cause of fast erosion of the middle part of roller surface, the present invention
achieved the solution to the problem by selectively configuring the middle diameter at
lower dimension compared to the two ends having higher diameter over desired length
such as to nullify the effect of abrasion in the middle portion. The gap in the middle
portion is selected to suit the loading of empty belt. Attention is now invited to the
accompanying Figure 1 wherein the concentric pipes/tube assembly (11) of two
selectively different diameters are found to be mounted on a common spindle (1) made of
bright bar, by means of seize resistant bearing (5) at two ends with housing (3) and
suitable spacers (2) and a cap (9) fixed with counter sunk rivet (10). The diameter of the
middle portion of the tubing is maintained selectively smaller in diameter than the two

extreme ends. It has already been stated that the wet and sticky coke granules deposited
in the middle portion of carrying side of conveyor belt have abrasive effect on the middle
portion of bottom idler/rollers and cause damage to the middle part of the pipe. To avoid
this abrasive wear and corrosion, an improved design configuration of the idler/roller
comprised concentric tubular construction wherein the central portion is fabricated from
smaller diameter preferably 88.9 mm pipe, over a length of 572 mm, while the pipes at
either ends of the idler/roller is configured to have larger diameter preferably 182.4 mm,
stretching over a length of 532 mm at the ends symmetrically, to nullify the effect of
abrasive wear of the pipe in the middle portion. The gap is thus selectively maintained to
suit the loading of the empty belt on return path. It is another aspect of the present
invention to develop an improved configuration of the idler rollers as described such that
the selective diameters of pipes used at the middle and the ends respectively, favor
running of the conveyor belt in the centre of rollers on the carrying side of conveyor and
provide means for automatic self-centering in return side, resulting in decreasing the
spillage of materials and thus help enhancing the belt life. Importantly also, the entire
surface of the variable diameter concentric steel pipes of idler rollers having improved
configuration is covered with rubber coating/lining (12) of selective thickness preferably
15mm thick, for the full length to avoid direct contact with the phenol water and hence
protecting the steel surface against corrosion.
The performance of the newly developed configuration having the aforesaid attributes, has
been put on trial in actual operation wherein the bottom rollers has been fabricated having
the constructional features as detailed above and installed on belt conveyors carrying
quenched coke as bottom idler/roller to support the empty conveyor load. The
performance trial on continuous operation of the coke oven plant and handling the
quenched coke on conveyor confirmed an enhancement of life by four times as compared
to the conventional bottom idler rollers used for the same purpose. The improved design
configuration of the bottom idler rollers also proved to be of great help when replacement
was essential. The end users because of improved life, easy to install and replace involving
simple steps and less time and manpower, prefer these return rollers according to the
invention. The down time of equipment/handling plant is significantly reduced with
reduction of frequency of roller damage and requirement of changeover. The replacement
of the improved idler rollers are also found to be simple to replace requiring less
manpower and less time of about 5 minutes as against the usual 15-20 minutes time for
the conventional configuration.

It is thus possible by way of the present invention to develop an improved configuration of
the idler/rollers for conveyors transporting the quenched coke such that the idler life is
enhanced, reducing the frequency of replacement requirement due to damage by either
phenolic water which is acidic in nature or abrasive wear by hard coke fragments sticking
to the conveyor carrying surface, thus reducing the downtime for repair/replacement and
enhancing the productivity in coke oven plant. The idler/rollers of the present configuration
also favor quick replacement with less manpower, making the system capable of longer
uninterrupted operation and thus favoring a wide range of industrial applications in
material handling and similar end uses.

We claim:
1. A bottom idler/roller for belt conveyor adapted for handling wet & sticky material
and/or with corrosive content such as handling of quenched coke comprising:
tubular steel pipe adapted to be mounted over an axle/ spindle having bearing housing
of suitable size and adapted such as to favour free rotation with the movement of the
conveyor when installed with respect to said stationary spindle mounted on brackets
comprising:
said tubular pipe having a middle portion of smaller diameter with the ends thereof of
greater diameter adapted to favour abrasion at the middle from said handling of the
wet & sticky material and/or with corrosive content.
2. A bottom idler/roller for belt conveyor as claimed in claim 1 wherein said tubular pipe
has a diameter in the middle of 88.9 mm to 98.9 mm and at the end of 152.4 mm to
182.4 mm.
3. A bottom idler/roller for belt conveyor as claimed in anyone of claims 1 or 2 wherein
the middle portion of smaller diameter defines a space /gap which is selectively
provided based on the loading of the empty belt.
4. A bottom idler/roller for belt conveyor as claimed in anyone of claims 1 to 3 wherein
the tubular pipe is obtained of as a single integral piece or plurality of concentric pipes
of stated dimensions with said smaller diameter pipe in the middle.

5. A bottom idler/roller for belt conveyor as claimed in anyone of claims 1 to 4 comprising
rubber lagging provided on the idler/roller pipe for safe guarding the steel against
corrosion.
6. A conveyor system for adapted for handling wet & sticky material and/or with corrosive
content such as handling of quenched coke comprising
bottom idler /roller as claimed in anyone of claims 1 to 5 mounted over axle /spindle
having bearing housing of suitable size such that the idler/roller rotates freely with the
movement of conveyor belt while spindle mounted on the brackets on both sides of the
stringer frame remains stationary.
7. A bottom idler/roller for belt conveyor and a conveyor system involving the same
substantially as hereindescribed and illustrated with reference to the accompanying
figures.

The present invention relates to an improved configuration of the bottom idler/roller for
belt conveyor adapted for reduced wear/corrosion and enhanced life of roller. More
particularly, the invention is directed to an improved corrosion resistant surface treatment
with rubber lagging on concentric pipes that form parts of said idler/rollers apart from
selective variable stepped diameter configuration of said idler/roller, especially for
conveyors handling quenched coke in coke oven plant. The idler/rollers on one hand helps
reducing the frequency of replacement and downtime for maintenance, on the other hand
ensure running of the conveyor belt centrally to thereby reducing the possibility of spillage
of material and thus enhancing the belt life. The idler rollers of the invention thus reduce
down time / maintenance time and cost and thus improving the productivity in coke oven
plant in terms of uninterrupted handling of quenched coke and thus having prospects of
wide industrial application in steel plants and the like. This type of bottom rollers when
used also eliminates the requirement of self centring device in return side of belt.