Apparatus for preloading a scraper blade in a conveyor cleaning system

An apparatus is provided for preloading a scraper blade against a conveyor belt in a conveyor cleaning system. The apparatus includes a blade support adapted to mount a scraper blade for engagement with a conveyor belt, a torsion member including a first end segment spaced from a second end segment along an axis, and a stop engageable with the second end segment to maintain the torsion member in a preloaded condition with the second end segment rotated about the axis relative to the first end segment to generate a preload between a scraper blade mounted on the blade support and a conveyor belt. In one form, the first end segment has an essentially polygonal cross section engageable with the blade support to restrict rotation of the first end segment relative to the blade support.

FIELD OF THE INVENTION 
This invention relates to conveyor cleaning systems, and more particularly, 
to apparatus for preloading a scraper blade against a conveyor belt in a 
conveyor cleaning system. 
BACKGROUND OF THE INVENTION 
Conveyor belt cleaning systems are commonly used to remove debris and other 
material adhering to the belts of conveyor systems. Such cleaning systems 
typically employ one or more scraper blades that are preloaded against the 
conveyor belt of a conveyor. It is not uncommon for the operating 
environment of such cleaning systems to be very hostile and often the 
environment may include combinations of moisture, dirt, abrasive 
materials, and/or corrosive materials and liquids. Additionally, belt 
joints or splices and large localized accumulations and/or large pieces of 
debris or material adhering to the belt must be accommodated by such 
conveyor cleaning systems. Given the demanding working environment and 
conditions commonly encountered by conveyor belt cleaning systems, there 
is a continuing need to provide conveyor belt cleaning systems which 
minimize the amount of maintenance, repair, and replacement required in 
order for the cleaning system to provide an acceptable cleaning/scraping 
of the conveyor belt. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an apparatus is provided for 
preloading a scraper blade against a conveyor belt in a conveyor cleaning 
system. The apparatus includes a blade support adapted to mount a scraper 
blade for engagement with a conveyor belt, a torsion member including a 
first end segment spaced from a second end segment along an axis, and a 
stop engageable with the second end segment to maintain the torsion member 
in a preloaded condition with the second end segment rotated about the 
axis relative to the first end segment to generate a preload between a 
scraper blade mounted on the blade support and a conveyor belt. 
In one form, the first end segment has a cross section that is non-circular 
over at least 25% of its outer periphery to engage the blade support to 
restrict rotation of the first end segment relative to the blade support. 
In one form, the first end segment has an essentially polygonal cross 
section engageable with the blade support to restrict rotation of the 
first end segment relative to the blade support. 
In one form, the polygonal cross section is essentially rectangular. 
In one form, the apparatus further includes a hollow stub shaft surrounding 
a portion of the torsion member. The stub shaft is engageable with the 
blade support to restrict rotation of the stub shaft relative to the blade 
support. The stub shaft is also engageable with a frame to restrict 
translational movement of the blade support relative to the conveyor belt 
while allowing rotation of the blade support about an axis relative to the 
conveyor belt. 
In one form, the hollow stub shaft and the portion of the torsion member 
have generally conforming circular cross sections to allow relative 
rotation between the torsion member and the hollow stub shaft. 
In one form, the blade support has a first end spaced from a second end, 
and the first end segment of the torsion member includes an elastomeric 
material. The first end segment is rotationally fixed to the blade support 
between the first and second ends of the blade support. 
In one form, the blade support has a receptacle extending from one of the 
first and second ends towards the other of the first and second ends. The 
first end segment of the torsion member is engaged within the receptacle 
to rotationally fix the first end segment to the blade support. 
In one form, the receptacle and the first end segment have generally 
conforming polygonal cross sections to rotationally fix the first end 
segment to the blade support while allowing the first end segment to 
translate relative to the blade support. 
In one form, the first end segment of the torsion member is engageable with 
the blade support to restrict rotation of the first end segment relative 
to the blade support, and the second end segment includes at least one 
stop surface. The stop includes a flange, an opening in the flange for 
receiving the second end segment, at least one pair of apertures in the 
flange spaced on opposite sides of the opening and extending from the 
opening into the flange, and a stop pin engageable with the at least one 
pair of apertures and the at least one stop surface of the second end 
segment to restrict rotation of the second end segment with the torsion 
member in the preloaded condition. 
In one form, the at least one pair of apertures is a plurality of 
circumferentially spaced holes extending radially through the flange, and 
the at least one stop surface is part of a cylindrical wall surface 
defining a hole extending through the second end segment of the torsion 
member. 
In one form, the first end segment is formed from an elastomeric material, 
and the second end segment is formed from a second material having a 
higher modulus of elasticity than the elastomeric material. The 
elastomeric material is connected to the second material between the first 
and second end segments to restrict rotation of the first end segment 
relative to the second end segment. One of the first and second end 
segments is engageable with the blade support to restrict rotation of the 
one segment relative to the blade support. The stop is engageable with the 
other end segment to maintain the torsion member in the preloaded 
condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As seen in FIG. 1, the invention is embodied in an apparatus 10 for 
preloading a scraper blade 12 against a conveyor belt 14 in a conveyor 
belt cleaning system 16. The apparatus 10 is mounted between a pair of 
spaced frame members 18, 19. 
As best seen in FIG. 2, the apparatus 10 includes a blade support 20 
adapted to mount the scraper blade 12 for engagement with the conveyor 
belt 14, a torsion member 22 including a pair of end segments 24, 26 
spaced from each other along an axis 28, and a stop, shown generally at 
30, engaged with the end segment 26 to maintain the torsion member 22 in a 
preloaded condition with the end segment 26 rotated around the axis 28 
relative to the end segment 24 to generate a preload between the scraper 
blade 12 mounted on the blade support 20 and the conveyor belt 14. The 
apparatus 10 further includes a pair of cylindrical stub shafts 32, 34 
which mount the blade support 20 and the torsion member 22 to the frame 
members 18, 19 via respective cylindrical bushings 36, 38 to restrict 
translational movement of the blade support relative to the conveyer belt 
14 while allowing rotation of the blade support 20 about the axis 28. The 
apparatus 10 also includes a pair of cylindrical locking collars 40, 42, 
each of which is engaged with one of the shafts 32, 34 to prevent 
translation of the shafts 32, 34, the torsion member 22, and the blade 
support 20 along the axis 28 relative to the frame members 18, 19. 
As best seen in FIGS. 2 and 3, the blade support 20 includes a tube 44 
having an essentially square cross section transverse to the axis 28, a 
blade mount 46 fixed to a side 48 of the tube 44, and a plurality of 
threaded bosses 50 fixed to another side 52 of the tube 44. The interior 
surface of the tube 44 defines a receptacle 53 having an essentially 
square cross section transverse to the axis 28 and extending from one end 
54 of the tube 44 to the other end 55 of the tube 44, as best seen in FIG. 
2. The blade mount 46 is formed from a pair of elongated members 56, each 
of which has an L-shaped cross section transverse to the axis 28. The 
blade mount 46 is adapted to engage an elongated slot 58 in the scraper 
blade 12. As best seen in FIG. 2, the blade mount 46 includes a pair of 
through holes 62 which are engaged by pins 64 to retain the scraper blade 
12 to the blade mount 46. While a specific form of the blade mount 46 has 
been described, it should be understood that the blade mount 46 may be 
configured to be compatible with any of the many various types of scraper 
blades employed in the art. While the tube 44, blade mount 46, and bosses 
50 may be formed of any suitable material that will provide adequate 
structural support for a scraper blade, it is preferred that these 
components be formed from a metal such as steel, with the members 54, 56 
provided in the form of an angle iron that is welded or brazed to the tube 
44, and the bosses 50 provided in the form of threaded nuts that are 
welded or brazed to the tube 44. Similarly, it should also be understood 
that the blade support 20 can be formed from a single unitary piece that 
is cast or machined to provide the required features, rather than being 
fabricated from multiple components. 
As best seen in FIG. 2, the end segment 24 of the torsion member 22 is 
preferably formed from an elastomeric material, such as 93 Ester or 93A 
Urethane, and the end segment 26 of the torsion member 22 is preferably 
formed of a material, such as steel, having a higher modulus of elasticity 
than the elastomeric material of the end segment 24. As best seen in FIGS. 
2 and 3, the end segment 24 extends into the receptacle 53 of the tube 44 
and has an essentially polygonal cross section in the form of a square 
transverse to the axis 28 that conforms to, and is thereby keyed within, 
the square cross section of the receptacle 53 and extends over a length X 
along the axis 28. The end segment 26 is preferably formed from a solid 
bar 70 having a polygonal cross section transverse to the axis 28 in the 
general form of a hexagon. The bar 70 extends into a receptacle 72 formed 
in the elastomeric material between the end segments 24, 26. The 
receptacle 72 has a polygonal cross section that generally conforms to the 
polygonal cross section of the bar 70 to restrict relative rotation 
between the end segments 24, 26. More specifically, an end 73 of the bar 
70 extends in the receptacle 72 to within a distance Y from the end 
segment 24. It should be appreciated that by varying the distance Y, the 
torsion member 22 can be configured to provide various torsional spring 
rates and thereby various preloading capabilities. More specifically, as 
the distance Y is decreased, the spring rate and preload capabilities of 
the torsion member 22 will be increased. Conversely, as the distance Y is 
increased, the torsional spring rate and preloading capabilities of the 
torsion member 22 will be decreased. Preferably, the elastomeric material 
is bonded to the bar 70 by a suitable bonding agent or by molding the 
elastomeric material around the bar 70. 
The elastomeric material surrounding the bar 70 extends continuously from 
one axial end of the blade support toward the other axial end of the blade 
support 20 over at least one half the distance between the ends of the 
blade support. 
One advantage of the polygonal cross sections of the end segment 24, the 
receptacle 53, the bar 70 and the receptacle 72 is that they provide a 
convenient form for a cross section that is non-circular, preferably over 
at least 25% of the outer periphery of the cross section, which keys the 
end segment 24 to the blade support 20 and thereby tends to provide 
effective shear resistance. 
The stop 30 includes a cylindrically shaped flange 72, a bolt flange 74, a 
cylindrical stop pin 76, and a cylindrical hole 78 extending through the 
end segment 26 of the torsion member 22 to define a stop surface 80 that 
engages the pin 78. The flanges 72, 74 are preferably made from a 
structural material, such as steel, and are integrally joined, such as by 
brazing, welding, or are machined or cast as a unitary piece. A 
cylindrical bore 82 centered on the axis 28 extends through the flanges 
72, 74. The bushing 38 is mounted in the bore 82 by an interference fit or 
by bonding or molding the bushing 38 to the bore 82. Accordingly, the 
flanges 72, 74 and the bushing 38 form an integral subassembly that is 
fixed to the frame member 19 via fasteners (not shown) that extend through 
a plurality of through bores 84 in the flange 74. An identical 
subassembly, using the bushing 36, is fixed to the frame 18 on the 
opposite side of the apparatus 10 to mount the stub shaft 32. While the 
bushings 36, 38 may be formed from any suitable bearing material, the 
bushings 36, 38 are preferably formed from 93 Ester or 93A Urethane. 
The flange 72 includes a pair of apertures 86, 88 spaced on opposite sides 
of the cylindrical bore 82, extending from the opening 82 into the flange 
72. Preferably, the apertures 86, 88 are provided in the form of a 
plurality of paired, cylindrical through holes 90 that extend radially 
through the flange 72 to allow the torsion member 22 to be maintained in a 
plurality of preloaded conditions with the second end 26 rotated about the 
axis 28 relative to the end segment 24. 
The stub shafts 32, 34 are preferably identical and formed from a suitable 
structural material such as cylindrical stainless steel tubing. Each of 
the stub shafts 32, 34 extends into the receptacle 53 of the tube 44 and 
is fixed to the blade support 20 by a plurality of square head set screws 
91 that are threaded into the bosses 50 to engage the stub shafts 32, 34. 
Each of the stub shafts 32, 34 includes a cylindrical through bore 92. The 
through bore 92 of the stub shaft 34 surrounds a cylindrical outer surface 
94 of the torsion member 22 that extends between the end segments 24, 26. 
A loose fit between the bore 92 and the surface 94 allows relative 
rotation between the stub shaft 34 and the torsion member 22. 
One advantage of the stub shafts 32, 34 is that they are located relative 
to the elastomeric material of the torsion member 22 and define walls with 
surfaces to shield the elastomeric material from contaminants, such as 
dirt and other materials and liquids from the conveyor belt 14, in the 
working environment of the cleaning system. The tube 44, the flanges 72, 
74 and the bushings 36, 38 also provide such shielding. 
The locking collars 40, 42 may be formed from any suitable structural 
material, such as from steel tubing. Each of the collars 40, 42 includes a 
threaded bore 96 that receives a square headed set screw 98 that locks the 
respective collars 40, 42 to their respective stub shafts 32, 34. The 
collars 40, 42 have respective bearing surfaces 98, 99 that extend 
perpendicularly to the axis 28 and bear against the respective frames 18, 
19 to restrict translational movement of the stub shafts 32, 34, the blade 
support 20, and the torsional member 22 along the axis 28. 
As best seen in FIG. 1, the apparatus 10 also includes a protective washer 
100 that is mounted to the end segment 26. More specifically, the washer 
100 includes a hexagonal opening 102 that conforms to the hexagonal cross 
section of an exposed portion of the end segment 26 which extends through 
the washer 100. A hitch pin 104 retains the washer 100 on the end segment 
26. 
In operation, the apparatus is assembled with the torsion member 22 in a 
"free" or unloaded condition, with no relative rotation between the end 
segments 24, 26. After the apparatus 10 is assembled to the frame members 
18, 19, a tool is used to engage either the hexagonal cross section of an 
exposed cantilevered portion of the rod 70 or a through hole 108 that 
extends through the exposed portion of the rod 70. With reference to FIG. 
1, a user then operates the tool to rotate the end segment 26 
counterclockwise relative to the end segment 24 to generate a 
predetermined preload between the scraper blade 12 and the conveyor belt 
14. When the counterclockwise rotation generates the predetermined 
preload, the stop pin 76 is engaged through the appropriate hole pair 90 
and the bore 80 in the end segment 26 to maintain the torsion member 22 in 
the preloaded condition with the end segment 26 rotated around the axis 28 
relative to the end segment 24. As the belt 14 is moved past the blade 12, 
the rotational mounting provided by the stub shafts 32, 34 and the 
bushings 36, 38 combines with the resiliency of the torsion member 22 to 
allow the blade 12 to follow the surface of the moving conveyor belt 14 
while encountering belt joints or splices in the conveyor belt 14 as well 
as large localized accumulations and/or large pieces of debris or material 
adhering to the belt 14. 
Further, as previously discussed, the stub shafts 32, 34, the tube 44, the 
flanges 72, 74 and the bushings 36, 38 tend to protect or shield the 
elastomeric material of the torsion member 22 from contaminants in, and 
moving through, the working environment. 
It should be appreciated that, because identical stub shafts 32, 34, 
identical locking collars 40, 42, and identical flanges 72, 74 and 
bushings 36, 38 are provided on each side of the apparatus 10, the 
apparatus 10 may be assembled with the end segment 26 of the torsion 
member 22 extending from either end 54, 55 of the blade mount 20 to engage 
either of the frame members 18, 19 via the stop 30. It should also be 
appreciated that the cross sections of the tube 44, the torsion member 22 
and the stub shafts 32, 34 allow translational movement of the torsion 
member 22 and the stub shafts 32, 34 along the axis 28 when the set screws 
93 are not engaged with the stub shafts, 32, 34. These features simplify 
the assembly of the apparatus 10 to the frame members 18, 19. It should 
further be appreciated that the conforming cross sections of the end 
segment 24 and the receptacle 53 allow the torsion member 22 to transmit 
torsional loads to the blade support 20 while also allowing translational 
movement of the end segment 24 relative to the tube 44 caused by the 
twisting of the torsion member 22. 
The foregoing disclosure of specific embodiments is intended to be 
illustrative of the broad concepts comprehended by the invention.