Note: Descriptions are shown in the official language in which they were submitted.
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CONVEYOR BELT SCRAPER BLADE
ASSEMBLY WITH CONTOURE~ STJRF~E
Background of the Invention
-
The present invention relates to conveyor belt
scraper blade assemblies and, more particularly, to scraper
blade assemblies adapted to clean older conveyor belts.
Conveyor belt assemblies of the type having a
flexible, endless belt are frequently used in mining oper-
ations to convey abrasive, particulate material. After
long periods of use, the flexible be]t, which may be a
fabric coated with rubber or polyvinyl chloride, tends to
stretch and wear such that the load-carrying surface of
the belt assumes a concave contour across its width. This
occurs in part because such belt systems employ troughed
idlers to support the belt so that it has a concave shape
in use to concentrate the load in the middle of the belt.
This troughing effect causes the belt fabric to stretch
along its middle.
When such belts are used to carry ~articulate
material which may be wetted, accumulations of m~terial
build up on the belt. Such accumulations are removed by
conveyor belt scrapers such as that shown in Stoll rJ.s.
Patent ~o. 4,402,394, which is commonly assigned. Such
conveyor belt scrapers include one or more scraper blades,
each having an elongate scraping blade surface which is
urged into contact with the load-carrying surface of the
conveyor belt, preferably on a return run of the conveyor
apparatus. The scraping surfaces of such blades are gener-
ally flat in shape, and therefore are unable to conform to
the concave contour of a worn conveyor belt in order to
remove accumulations of material from the central portion
of the belt.
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Attempts have been made to develop conveyor belt
scrapers which are capable of conforming to the contour of
the conveyor belt. Such an apparatus is exemplified by
the blade shown in Matson V.S. Patent No. 3,~04,78~. That
patent shows a conveyor belt scraper assembly which com-
prises a plurality of scraper blade segments which are
mounted on the ends of rods attached to a bar spanning the
width of ~he conveyor belt and mounted on a support which
rotates the bar to urge the blades into contact with the
belt. The blade segments are each sizea and positioned to
extend across only a part of the belt, and the rods are
sufficiently flexible so that the blade segments are indi-
vidually biased to engage an associated part of the belt,
whether the belt is substantially flat in contour or has a
convex shape.
A disadvantage with such designs is that the
large number of parts required to fabricate such an assem-
bly results in an increased cost of production and high
maintenance costs. Furthermore, the use of individual
blade segments which are urged into the load-carrying
surface of the belt by resilient rods often results in the
"chattering" of the blade segment, during which it bounces
into and out of contact with the belt surface. This sub-
stantially reduces the efficiency of the blade scraper
since the individual scraper elements are in contact with
the load-carrying surface on a less-than-constant basis
during use.
Accordinqly, there is a need for a conveyor belt
scraper blade assembly which is capable of conforming to
the concave contour of a worn conveyor belt, and which is
relatively low-cost and does not have a high maintenance
requirements. There is also a need for a conveyor belt
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scraper blade assembly which reduces the likelihood of
blade chatter, and therefore increases the efficiency o
material removal.
Summary of the Invention
The present invention is a conveyor belt scraper
blade assembly which utilizes a continuous blade body
having a concave shape which matingly engages the convex
shape of the worn conveyor belt. The blade assemblv in-
cludes an elongate blade body made of a resilient material
and having a longitudinally-extending belt scraping sur-
face, a frame attached to the body for imparting a convex
shape to the belt scraping surface, and brackets attached
to the ends of the frame which are adapted to be attached
to a suitable supporting structure.
In a preferred embodiment of the invention, the
scraping surface consists of a pair of continuous surface
portions positioned on opposing longitudinal sides of the
blade body, and the blade body includes a central, longi-
tudinally-extending slit. The frame includes an insert
having a double convex shape which is inserted into the
slit. The double convex shape of the insert imparts a
convex contour to both of the surface portions of the
blade body.
The frame also includes a pair of side bars which
extend along the outer side walls of the blade body and
are attached to the insert. The side panels include a
plurality of inwardly-directed prongs which en~age the
blade body and hold it in position relative to the insert.
The brackets are attached to the ends of the side panels
and are shaped such that the blade body may be positioned
to place either of the two surface portions into contact
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with a conveyor belt, so that as one surface portion
becomes worn and unusable, the blade may be rotated to
place the other surface portion into engagement with the
belt. This design effectively doubles the useful life of
the scraper blade assembly.
An advantage of the use of a continuous scraper
blade body is that the likelihood of blade chattering is
minimized, since there is a single blade contacting the
conveyor belt, and that blade is supported securely at its
ends by a rigid frame structure. Another advantage of the
present invention is that the design can be modified to
accomodate blade bodies having different comPositions
which may be useful in certain selected applications. For
example, the blade body may consist of a central portion
made of a relatively soft rubber (40 durometer) sandwiched
between outer layers of a relatively hard rubber (6~ duro-
meter).
The structure of the preferred embodiment pos-
sesses an advantage over a comparably shaped blade made of
a solid slab of material. If the scraping surface of the
latter extruded far enough above the side panels to give
reasonable blade life, folding over of the unsupPorted
portion of the blade would occur. In addition a substan-
tial portion of such a blade would be unusable since it
would be covered by the side panels.
Accordingly, it is an object of the present inven-
tion to provide a conveyor belt scraper blade assembly
which is particularly adapted for use with worn conveyor
belts having a concave shape; a scraper blade assembly
having a continuous belt scraping surface to engage worn
belts; and a conveyor belt scraper blade assembly which is
relatively inexpensive to manufacture and maintain.
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Other objects and advantages of the invention
will be apparent from the following description, the accom-
panying drawings, and the aPpended claims.
Brief Description of the Drawings
.
Fig. l is a perspective view of a ~referred embod-
iment of the conveyor belt scraper blade assembly of the
present invention, shown mounted on supportina structure
and engaging a conveyor belt;
Fig. 2 is an exploded, perspective view of the
scraper blade assembly of Fig. l; and
Fig. 3 is a front elevational view of the scraper
blade assembly of Fig. l.
Fig. 4 i8 a view looking toward the belt scraping
surface.
Detailed Description of the Preferred Embodiment
As shown in Fig. l, the conveyor belt scraper
blade assembly of the present invention, aenerally desi~-
nated l0, is particularly adapted to be used in combination
with a worn conveyor belt 12 of the type having a concave
contour in a transverse direction. The scraper blade
assembly l0 includes an elongate blade body 14, a frame
16, and a pair of brackets 18, 20 which are attached to
the frame and are adapted to be attached to the support
arms 22, 24 of a supporting structure 26. The supporting
structure 26 may be a conveyor belt scraper of the type
shown in Stoll U.S. Patent 4,402,394, commonly assigned,
the disclosure of which is incorporated herein by refer-
ence.
As shown in Figs. 2, 3, and 4, the blade body 14
is a composite having a central core or plate 28 of a
relatively soft material, such as 40 durometer rubber, and
outer layers or plastics 30 of a relatively hard material,
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such as 60 durometer rubber. It is within the scope of
the invention to utilize blade bodies 14 made of a urethane
or of solid rubber. Depending on the desired application,
the rubber could vary from 40 to gO durometer.
The blade body 14 includes a longitudinally-
extending, continuous belt scraping surface, generally
designated 32, which comprises a pair of scraping surface
portions 34, 36, located on opposite sides of the blade
body 14. The scraping surface portions 34, 36 each have a
convex shape which matingly engages the concave shape of
the conveyor belt 12. That is, the distance from the
mid-portion of either scraping surface to a central longi-
tudinal axis A of the blade assembly 10 (see Fig. 3) is
greater than the distance of the end portions of the scrap-
ing surfaces from the central longitudinal axis.
The convex shape of the scraping sur~ace portions
34, 36 is the result of a double convex insert 38 which is
positioned within in a central longitudinal slit 40 formed
in the blade body 14. The insert 38 consists of upper and
lower bars 42, 44, respectively, welded together at their
ends and bowed apart by a central strut 46 welded to the
bars.
The frame 16 also includes a Pair of side bars
48, 50, which extend along the side walls 52, 54 of the
blade body 14. The side bars 48, S0 each include upper
and lower arcuate portions 56, 58 that correspond to the
double convex contour of the insert 38, so that the insert
extends between the arcuate members. The side bars 48,
50, like the insert 38, are made of steel and are welded
to the insert to form an integral frame. Gang nail plates
60 are welded to the inside walls of the side bars 48, 50
and are spaced along their lengths. Each nail plate 60
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includes inwardly-directed prongs 62 which engage the side
walls 52, 54 of the blade body 14 and secure the blade
body in position relative to the insert 38.
The side bars 48, 50 include end plates 64, 66
which are bent at right angles to the arcuate members 56,
58 and include cutouts 6~ for receiving the end brackets
18, 20. The brackets 18, 20 each include a plate-shaped
base 70 and a cruciform extension 72. The bases 70 extend
through the openings formed by the engaging cutouts 68 of
the end plates 64, 66 and are welded in position.
As shown in Fig. 1, the cruciform extensions 72
are received within correspondingly-shaped openinqs formed
in plate brackets 73 abutted to the support arms 22, 24 of
the supporting structure 26. The cruciform shape is sym-
metrical so that the scraper blade assembly 10 may bepositioned to place either of the scraPing surface portions
34, 36 into contact with the conveyor belt 12.
In operation, the scraper blade assembly 10 is
mounted on the supporting structure 26, and oriented such
that the scraping surface portion 34 is urged into the
concavity of the conveyor belt 12. The convex shape of
the surface portion 34 results in a continuous line of
contact with the conveyor be~t across its width. When
surface 34 is worn, the blade 10 may be rotated 180 about
axis A, thereby presenting surface 36 to the belt 12.
While the form of apparatus herein described
constitutes a preferred embodiment of the invention, it is
to be understood that the invention is not limited to this
precise form of apparatus, and that changes may be made
therein without depar~ing from the scope of the invention.
What is claimed is:
