FIELD OF THE INVENTION
The present invention in general relates to belt scrapers used in bulk material
handling belt conveyors and in particular to an improved belt scraper assembly which
can be mounted on the head pulley so that the cleaned material falls close to the
center of the chute. The scraper has segmented blade body and is capable of
avoiding obstacles without producing any threat of damage to the belt surface.
BACKGROUND OF THE INVENTION
Belt Scrapers are used in bulk material handling belt conveyors to avoid material
carry back, reduce spillage and keep belts clean. Clean belts help prevent material
build up on snub pulley and return idlers and increase their life, thereby reducing
cleaning cost, downtime cost and miss-tracking of the belt.
In first generation counter-weight belt scraper, single blade design is made from
thick rubber strip (wider than belt width) under the return belt and the counter
weights are provided at the side of the belt scraper with a pivot point to provide
contact with the belt. The initial load exerted on the belt is approximately 80 - 90
Kgs. With use, when the cleaning effectiveness reduces, the weight is gradually
increased and can go up to 150 Kgs.
Cleaning efficiency is approximately 60-68 % and it is necessary to increase counter
weight load on a regular basis to counter the effect of blade wear. Such scrapers are
not very effective and involve high maintenance.
Second generation fixed mount belt scrapers have segmented blades which are
made of hard alloy steel with rubber cushion at the bottom of the blades. The blades
are mounted on a steel tube having a both ends fixed mount. It does not have
automatic adjustments against blade wear. It provides an inconsistent contact
pressure, which is approximately 100 - 125 Kgs, to the belt.
Cleaning efficiency of such scrapers is approximately 70-85 % and there is always, a
need to raise the fixed mount on a regular basis to counter blade wear. Such
scrapers too are less effective and involve high maintenance.
Pneumatically operated third generation belt scrapers have segmented blades which
are made of hard alloy steel with or without polymer cushion at the bottom of the
blades. The blades are mounted on a steel tube with ratchet-and-pinion mounts

which are adjusted through compressed air at 7-10 bars pneumatically. They provide
inconsistent load of approximately 90 - 110 Kgs to the belt. Cleaning efficiency is
approximately 75-85 %. Moreover, there is a need to pump air periodically to
maintain proper blade-to-belt contact due to drop in air pressure / leakage /
chocking of air. Maintenance requirement is high.
In the fourth generation belt scrapers with shock absorbers, semi automatic
adjustments are present to some extent. But there is a need for periodic manual
adjustments against blade wearing every 3-4 weeks. This type of belt scrapers
have segmented metallic blades with pivot point below the scraping edge mounted
on a steel tube with both ends mounted on rubber shock absorbers. It provides
comparatively less load to the belt, which is approximately 24 - 80 Kgs. Cleaning
efficiency is approximately 92-95 %. It provides less consistency in heavy duty, high
speed, vibration and bi-directional belt operation applications.
Above mentioned scrapers of the prior art are all installed at a position off the head
pulley. But cleaning at this position causes the material to accumulate along the
chute wall and eventually cover the scraper itself. It is always desirable that the
cleaned material should move with the main materials flow which takes place close
to the centre of the chute. There are a few scrapers made to scrap the material from
the belt surface on the head pulley itself, but these belt scrapers are not as efficient
as the scrapers installed off the head pulley. Clearly, the above mentioned
conventional belt scraper assemblies are far from the desired scrapper and suffer
from one problem or the other while in operation.
Accordingly there is a long felt need to design a belt scraper assembly which ensures
that the cleaned material falls close to the center of the chute, efficient belt cleaning,
automatic adjustment of the blades, lesser wear out rate of the blades and no
material build up. It also must achieve size reduction and be adapted to easy
installation, suitable for different belt speeds and reduce maintenance costs. It
should be suitable for various types of material and operating in corrosive
environment and provide easy joining of sub-assemblies.
The present invention meets the aforesaid long felt needs.

All throughout the specification including the claims, the words "conveyor belt",
"scraper blade" "scraper holding arm", "torsion spring", "compression spring", "lead
screw", "washer", "blade", "blade tip", "blade tip assembly ", "spring", "fasteners"
"hinge assembly", "lock", "pin", "bellow", "angle" and "nut" are to be interpreted in
the broadest sense of the respective terms and includes all similar items in the field
known by other terms, as may be clear to persons skilled in the art.
Restriction/limitation, if any, referred to in the specification, is solely by way of
example and understanding the present invention.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved belt scraper
assembly for belt conveyors which ensures efficient cleaning of the belt surface,
which is capable of being installed on the head pulley and which ensures avoidance
of the blade tip getting damaged by a mechanical fastener if attached with the belt.
Such mechanical fasteners are used to join two belt surfaces.
It is another object of the present invention to eliminate misalignment of blades.
Misalignment in the blades reduces the cleaning efficiency of the scraper as it allows
material to pass between two blades. The present invention ensures minimum
misalignment with easy assembly process.
It is another object of the present invention to ensure automatic adjustment of the
blades, lesser blade wear rate and no material build up.
It is a further object of the present invention to provide an improved belt scraper
assembly for belt conveyors which ensures size and weight reduction and easy
installation.
It is another object of the present invention to provide an improved belt scraper
assembly for belt conveyor which is suitable for variable belt speeds and reduces
maintenance costs.
It is yet another object of the present invention to provide an improved belt scraper
assembly for belt conveyor which is suitable for variable materials and is suitable for
working in corrosive environment.

It is a further object of the present invention to provide an improved belt scraper
assembly for belt conveyors which is suitable for used up to 200°C ambient
temperature.
It is a further object of the present invention to provide an improved belt scraper
assembly for belt conveyors which ensures easy joining of the subassemblies.
How the foregoing objects are achieved and other aspects of the present invention
will be clear from the following description which is purely by way of understanding
and not by way of any sort of limitation.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an improved belt scraper assembly for
belt conveyors suitable for mounting on the head pulley comprising of a plurality of
blade subassemblies, a mounting structure and two side-mounting subassemblies to
ground the whole assembly and provide translatory motions in perpendicular
directions. The assembly is provided with a torsion spring for providing the flipping
action required to disengage the blades in case a blade fastener or protrusion in the
belt surface appears and for preventing the blade tip from being damaged. The
assembly also has a compression spring to provide automatic continuous adjustment
of the scraper blades to keep the blades in contact with the belt surface in the event
of the blades wearing out.
In accordance with preferred embodiments of the belt scraper assembly of the
present invention:
-said blade subassembly consists of blade tip , blade body , a torsion spring , a
plurality of bushes , slotted pins , a rivet, a blade body pin, a compression spring
and a cap;
-said blade tip is made of high resistant metal brazed on a plate of metal body;
-said torsion spring has legs at both ends of the spring which are clamped by said
slotted pins at both the ends;

-said slotted pin is placed within hole of said blade block element, clamped to one leg
of said torsion spring which is also placed within hole and then fixed to the blade
block element whereas said slotted pin is clamped to the other leg of said torsion
spring and then fixed to the blade body , the arrangement providing a fully covered
torsion spring action to the assembly;
-said torsion spring is provided with a pre-tension during the assembly of said blade
subassembly;
-said mounting structure is connected to two side mounting subassemblies at both
the ends of the structure which ground the structure;
-said side mounting subassembly is provided with arrangement to move the scraper
in two perpendicular directions;
-all the components of the assembly can withstand temperature of up to 200°C
ambient;
-all the blades are aligned at a uniform angle throughout the life of the scraper;
-said uniform angle of alignment of the blades is achieved by pre-tensioning of
torsion spring and by the design of the blade element acting as a stopper.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from the
accompanying drawings, which are by way of illustration of a preferred embodiment
and not by way of any sort of limitation. In the accompanying drawings,
Figure 1 is the side view of the complete scraper assembly.
Figure 2 is the front view of the complete scraper assembly.
Figure 3 is an isometric view of the side mounting subassembly of the scraper.
Figures 4 is an side view of the side mounting subassembly of figure 3 indicating the
connections between its different components.

Figure 5 is an isometric view of the side mounting subassembly indicating
connections between different components.
Figures 6a to 6c are three isometric views of different components of the side
mounting subassembly.
Figure 7 is an isometric view of the blade subassembly.
Figure 8 is a blown up isometric view of the blade subassembly which is connected to
the angle, showing its important components.
Figure 9 is the front view of the blade subassembly of figure 7 showing the
connections between its various components.
Figure 10 is an isometric view of different components of the blade subassembly.
Figure 11 is an isometric view of the blade body and the blade body pin.
DETAILED DESCRIPTION OF THE INVENTION
The following describes a preferred embodiment of the present invention, which is
purely for the sake of understanding the performance of the invention, and not by
way of any sort of limitation.


The present invention brings all the above changes in a way never done before. The
blade elements in the present invention have two degrees of flexibility, one along the
belt for obstacle avoidance and another perpendicular to the belt surface for
automatic adjustment. Both the flexibilities result in scraper disengagement in case
the pressure between the blade and the belt increases.
For understanding the invention better, reference will now be made to the following
preferred embodiment of the invention, which is illustrated in the accompanying
drawings.
In the figures like reference numerals represent like features.
Turning first to figure 1, it shows the side view of the complete scraper assembly and
the relative positions of the blade subassembly (2), angle (1) and side mounting
subassembly (3), which is best shown in figure 3.
Figure 2 shows the front view of the complete scraper assembly. It shows the
connection of a plurality of blade subassemblies (2) with the angle (1) and the
connection of angle (1) with the side mounting sub assembly (3) at the two ends.
Figure 3 shows the isometric view of the side mounting subassembly (3). Reference
. is also made here to figures 6a, 6b and 6c for detailing. Subassembly (3)
incorporates lead screws (15) and (14) which allow its movement in two
perpendicular directions. Frame (16) is used to attach angle (1) with the side
mounting subassembly (3). Main frame (12) is bolted to the chute periphery using
holes (30) for fixing the whole scraper assembly. Main frame (12) also has two bolt
holes (28, 29) on two opposing side walls (best shown in figure 6a). A rectangular
block (13) is connected with main frame (12) using fastener (14) which goes through
the holes (31, 32, 28 and 29), best shown in figures 6(a) and 6(b), which are
present on rectangular block and main frame respectively. A circlip (17) is used to
hold the fastener (14) at its position and lock its translatory motion, allowing only
rotatory motion. An elongated body part or edge (35) of rectangular block (13) slides
over a top surface part of the main frame (12). Frame (16) is connected to the
rectangular block (13) using patches (25, 26, 18 and 27), best shown in figure 4.
The linear motion to the frame (16) is provided by using the lead screw principle.

Figure 4 shows the side view of the side mounting subassembly (3) indicating the
connection between its different components, namely frame (16), patches (25, 26,
18, 27) and rectangular block (13).
Figure 5 shows an isometric blown up view of the side mounting subassembly (3)
indicating connections between its different components, namely frame (16), patches
(25, 26, 18 and 27), rectangular block (13), main frame (12), fastener (14), circlip
(17) and lead screw (15).
Figures 6a to 6c show isometric views of different components of the side mounting
subassembly with their detailing.
Figure 6a shows the main frame (12) which is adapted to be fixed with the chute
periphery using holes (30) for grounding the whole scraper assembly. The elongated
body of main frame (12) contains bolt holes (28, 29) on its two opposing side faces,
through which the fastener (14) passes.
Figure 6b shows the rectangular block (13), an edge (35) of which slides over a top
surface of the main frame (12). The block has holes (31, 32) on its two vertical
sidewalls through which said fastener (14) passes. The top face of the rectangular
block (13) has a hole (34') through which lead screw (15) passes.
Fig 6c shows details of constructional features of frame (16). The bolt holes (33) are
present on one sidewall of the frame (16). The angle (1) is connected with frame
(16) by bolting through these holes (33). The top and bottom surfaces have bolt
holes (34) through which lead screw (15) passes.
The side mounting subassembly (3) is connected to the angle (1). There are two
such side mounting subassemblies at both ends of the angle (1). Angle (1) contains
a series of holes to hold the plurality of blade subassemblies (2), best shown in
figure 2. The angle (1) ensures automatic adjustment of the blades.
Reference is now made to figures 7 and 8. Figure 7 shows an isometric view of the
blade subassembly (2), while figure 8 gives the details of its components primarily
related to compression spring (24) and its assembly. A plurality of blade
subassemblies is connected to angle (1) using blade body pins (20) and caps (22).
Pin (20) passes through a vertical blade block element (4), compression spring (24),
a spring cover (23) and the angle 1, not shown in these figures. Cap (22) is used to
close the hole in blade block element (4).

With this arrangement, the compression spring (24) provides the required
suspension to the blade block element (4). It also provides the forward force for
automatic continuous adjustment of the scraper blades and for keeping the blades in
contact with the belt surface even as the blades wear out. This eliminates the need
of frequent maintenance required to keep adjusting the scraper to compensate for
the wear of the blades.
Coming to figures 9, 10 and 11, blade block element (4) is connected to blade body
(6) using pins (8) and (10) respectively. These three drawings collectively show the
connections between different components of the blade assembly used mainly to
connect the two springs, namely the torsion spring (5) and the compression spring
(28) with the blade body.
Bush (7) is a covering provided at both ends for the hole (36) on block element (4),
best shown in figure 10. Bush (7), which allows proper rotation of blade body (6),
has a sealing outer rim (39), second rim (38) and internal hole (37) which
accommodates pins (8) and (10). Torsion spring (5) is placed inside hole (36) of the
blade block (4). Torsion spring (5) is provided with legs (45) which are present at
both ends of the spring. One leg is clamped in the gap (42) of pin (10) and the other
leg is clamped in the gap (43) of pin (8). Pin (8) is riveted to blade block (4) using
hole (19) on the blade block element (4). Pin (10) is connected to the blade body (6)
by screwing at the points (47) and (48) on the blade body, best shown in figure 11,
and holes (40) on the pin (10). The blade tip (9) is attached at the front part (46) of
the blade body (6) through brazing or similar means. The blade tip (9) is made of a
hard and wear-resistant material. In the present case it is a tungsten carbide tip
brazed on a plate named here as the blade body.
Before assembly, hole (44) on the pin (8) lags 10 degrees with respect to hole (19)
on the blade block element (4). This is achieved by having a 10 degrees difference in
the two legs (45) of the torsion spring (5). At the time of assembling, the pin (8) is
rotated by 10 degrees such that hole (44) coincides with hole (19). While doing so
one of the legs (45) of torsion spring (5) clamped by pin (8) is also twisted giving a
pre-tension to the torsion spring i.e. the torsion spring has already been rotated by
10 degrees before the assembly is put into operation.
This pre-tensioning enables use of a torsion spring having a lower wire diameter,
consequently reducing the overall dimension of the whole assembly because all other
dimensions are based on the dimension of the torsion spring. Secondly, the pre-

tensioning rotates the blade body (6) till the edge of the blade block element (4)
provides a uniform angle to all the blade bodies in the whole assembly (irrespective
of the clamping clearance of the torsion spring).
After clamping of the two ends of the torsion spring (5) by pins (8) and (10), pin (8)
is twisted to provide a pre-tensioning force to the torsion spring (5). Pin (8) is
rotated till hole (19) on blade block element (4) and hole (44) on pin (8) coincide
and a rivet is placed in the two concentric holes. This results in a uniform angle for
all the blades and eliminates the chance of misalignment at the time of assembly. So
the uniform angle of alignment of the blades is achieved by pre-tensioning of torsion
spring and by the design of the blade element acting as a stopper. All the blades are
aligned at a uniform angle throughout the life of the scraper.
The torsion spring (5) provides the flipping action required to disengage the blades in
case a blade fastener or protrusion in the belt surface appears. This feature protects
both the belt and the blade tip from being damaged.
From the foregoing description and the appended claims it should be clear that all
the desired objectives of the present invention are fulfilled.
The present invention has been described with reference to some drawings and
preferred embodiments, purely for the sake of understanding and not by way of any
limitation and the present invention includes all legitimate developments within the
scope of what has been described hereinbefore and claimed in the appended claims.

We Claim:
1. An improved belt scraper assembly for belt conveyors suitable for mounting on
the head pulley comprising of a plurality of blade subassemblies (2), a mounting
structure (1) and two side-mounting subassemblies (3) to ground the whole
assembly and provide translatory motions in perpendicular directions, said assembly
being provided with a torsion spring (5) for providing the flipping action required to
disengage the blades in case a blade fastener or protrusion in the belt surface
appears and for preventing the blade tip from being damaged, the assembly also
having a compression spring (24) to provide automatic continuous adjustment of the
scraper blades to keep the blades in contact with the belt surface in the event of the
blades wearing out.
2. The improved belt scraper assembly as claimed in claim 1, wherein said blade
subassembly (2) consists of blade tip (9), blade body (6), a torsion spring (5), a
plurality of bushes (7), slotted pins (8, 10), a rivet, a blade body pin, a compression
spring (24) and a cap (22).
3. The improved belt scraper assembly as claimed in claim 2, wherein said blade tip
(9) is made of high wear resistant metal brazed on a plate of metal body (6).
4. The improved belt scraper assembly as claimed in claim 2, wherein said torsion
spring (5) has legs (45) at both ends of the spring which are clamped by said slotted
pins (8, 10) at both the ends.
5. The improved belt scraper assembly as claimed in claim 4 , wherein said slotted
pin (10) is placed within hole (36) of said blade block element (4), clamped to one
leg (45) of said torsion spring (5) which is also placed within hole (36) and then fixed
to the blade block element whereas said slotted pin (8) is clamped to the other leg
(45) of said torsion spring (5) and then fixed to the blade body (6), the arrangement
providing a fully covered torsion spring action to the assembly.
6. The improved belt scraper assembly as claimed in claim 2, wherein said torsion
spring (5) is provided with a pre-tension during the assembly of said blade
subassembly (2).

7. The improved belt scraper assembly as claimed in claim 1, wherein said mounting
structure (1) is connected to two side mounting subassemblies (3) at both the ends
of the structure which ground the structure.
8. The improved belt scraper assembly as claimed in claim 1, wherein said side
mounting subassembly (3) is provided with arrangement to move the scraper in two
perpendicular directions.
9. The improved belt scraper assembly as claimed in claim 1, wherein all the
components of the assembly can withstand temperature of up to 200°C ambient.
10. The improved belt scraper assembly as claimed in claim 1, wherein all the blades
are aligned at a uniform angle throughout the life of the scraper.
11. The improved belt scraper assembly as claimed in claims 1 and 10, wherein said
uniform angle of alignment of the blades is achieved by pre-tensioning of torsion
spring and by the design of the blade element acting as a stopper.

ABSTRACT

An improved belt scraper for belt conveyors suitable for mounting on the head pulley
comprises blade subassemblies (2), angle (1) and side-mounting subassemblies (3).
Torsion spring (5) and compression spring (24) provided in blade subassembly (2)
provide automatic continuous adjustment of scraper blades and keep scraper blades
in continuous contact with the belt surface. The blade subassembly (2) consists of
high resistance metal tip (9), metal blade body (6), torsion spring (5), bushes (7),
compression spring (24) and cap (22) and provides full torsion spring action to the
assembly. The said torsion spring (5) is given a pre-tension during the assembly of
the blade subassembly (2). The compression spring (24) provides suspension to
blade block element (4), forward force for automatically adjusting scraper blades for
less wear. Blades are kept aligned at a uniform angle throughout the life of the
scraper.
The scraper can withstand a temperature of 200°C ambient.