Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
A FOLDING BELT SYSTEM AND SAID BELT
Technical Field
This invention relates to a folding belt conveyor
systems and more particularly relates to folding belts
and methods of making the same. This conveyor system,
adapted to move a folding conveyor belt by means of the
usual drive rolls while supported on idler rolls, has a
folding belt which in one view is a conventional belt
having a pair of continuous, flexible, longitudinal
cover flaps attached hingeably along each longitudinal
edge of said belt to permit the flaps to be folded to
fully cover the load and confine the material being
conveyed on the belt or to move to the axially unfolded
position. This folding belt may be loaded with the
cover flaps unfolded to the fully opened position or
with the cover flaps unfolded only sufficiently to
permit on-loading of the material. The width, W, of a
folding belt is defined as the distance between the two
longitudinal hinges. This dimension W defines the
conveying capacity of the belt at a specified speed.
First, the inherent containment provided by the cover
flaps allows a fold belt to be loaded all the way to
its hinge area, thus eliminating the unused edge
distance required by conventional belting to prevent
spillage. This allows a fold belt to carry a
substantially greater load than a conventional belt on
the same width conveyor system. Thus, a folding belt
conveyor system with a belt width of W can carry a
larger load than a conventional belt of the same width
of W. At its minimum and maximum capacity the folding
belt can carry a load respectively 50 and 100 percent
more relative to the conventional belt of the same
width W and also protect the load from external
contamination. In addition, the enclosed load feature
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of the fold belt can substantially reduce the need for
metal shrouding in applications where dust is a
problem. This also ofers many advantages including
easier conveyor maintenance and reduced dust collecting
systems requirements. The result can be improved
conveyor safety and reduced costs. And finally, by
containing the load with its flaps, a fold belt is able
to convey materials up steeper inclines and operate at
higher speeds with less spillage than conventional
belts. Consequently, conveyor operation time can be
reduced while efficiency is increased.
Prior Art
The conventional flexible belt conveyor systems
are open and thus the material carried on the belt can
be contaminated by rain, dust and related contaminates
as the conventional belt i5 open to the atmosphere.
Consequently, the trade has resorted to metal shrouding
or related enclosure means to protect the belt from
contamination, but this shrouding increases the volume
for the accumulation of dust and thereby allows for the
creation of large masses of explosive mixtures.
Although the folding belt conveyor systems are known,
these systems require special hardware for the conveyor
system or were subjected to appreciable spillage due to
the belt construction. This material loss and
accumulated dust contributed to the explosion hazards
in handling coal, ore, minerals, grain, feed, and flour
to mention only a few of the bulk materials handled on
con~eyor belts.
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2a
Summary of the Invention
Various aspects of this invention are as follows:
A cured reinforced plastic or elastomeric belt for use
on a continuous self closing belt conveyor comprising a
multiply belt having two displaced longitudinal fold areas
to allow said belt to fold to give a fully enclosed belt,
said longitudinal fold areas being formed by removing at
least one ply of said belt in each fold area and
essentially at equal distances from the respective
longitudinal edge of the belt for each fold area.
A method of forming a belt capable of folding to give an
enclosed belt comprising forming a multiply cured belt,
forming two longitudinal fold areas with each longitudinal
fold area being displaced a like distance from
longitudinal edge of said belt by removing at least one ply
from said belt in each area.
Disclosure and Practice of the Invention, Including
the Best Mode
The nature of this invention and its advantages and
benefits can be seen and understood by referenca to the
drawings wherein:
Figure l is a schematic plan view of the conveying
apparatus of this invention,
Figure 2 is a schematic elevational view of the
apparatus having a tensioning means in the tail
terminal.
Figure 3 is a schematic elevational view of the
apparatus of Figure 1 having the tensioning means near
the head terminal.
Figure 4 is a cross-sectional view through Figure
l along lines 4-4 showing the minimum and maximum
additional load carrying capacity aspect of the
conveying apparatus.
Figure 5 is an enlarged view of the transition
area of the conveying apparatus showing the width of
the terminal pulley and the idler rolls relative to W,
the width of the belt between the fold lines.
Figure 6 is an enlarged view of the tail terminal
showing an embodiment having a loading chute positioned
in the apparatus whereby the belt can be on-loaded
without fully opening the flaps.
Figure 7 is a cross~sectional view of a
conventional belt which has had two longitudinal
sections removed to form the fold lines.
Figure 8 is a cross-sectional view showing a
conventional belt partially cured and folded over to
form two fold lines and then fully cured in this
position to yield a folded belt.
Referring to the drawings and specifically figures
1, 2, and 3 a folding belt conveyor 10 is shown in
schematic outline where numeral 11 designates the
folding belt. The belt 11 passes over a head roll,
herein designated as pulley 13, and a tail roll herein
designated as pulley 12. These head and tail rolls are
sometimes called terminals. The belt intermediate the
head and tail terminals is supported by a series of
conventional idler rolls 14 as best seen in figures 2
and 3. Preferred forms of the idler roll as shown in
Figure 4 comprise three in line rolls 15 mounted to
cause the belt to form the conventional trough shape.
It should be appreciated that roles 14 can be straight
or any other shape in conveyor usage. Also, the
conveyor system may have tension means such as the ones
shown in Figures 2 and 3 and designated generally as a
tail tension means 17 and a head tension means 18. The
amount of tension on the tail roll 12 is controlled by
applying weights 19 to the tension member 20 usually a
chain, rope, or cable that passes over tension pulley
21 and has one end attached to the tail roll 12 in a
manner to permit the tail roll 12 to rotate under
suitable rotation means such as a motor driven roll
(not shown) and thus moves the belt in the direction
indicated by arrow 22. The tension system used at the
head end preferably is positioned as shown in Figure 3
as this allows the load on the belt to be discharged
without being obstructed by the tension means. The
tension means shown in Figure 3 comprises rolls 23 and
24 having a tension roll 25 positioned between rolls 23
and 24 to pull the belt down tight in the manner shown
in Figure 3. The amount of pull down or tension
applied to the belt is a function of the amount of
weights 27 attached to one end 28 of tension member 26
and having its other end 29 attached rotatably to
tension roll 25.
Referring again to Figure 1, the folding belt 11
is unfolded 31 as it passes around tail roll 12 and
head roll 13. Therefore, the tail roll 12 and the head
roll 13 has to be at least twice the width of the belt
between the fold lines 30. Also, the head and tail
rolls are twice the width of the idler rolls 14. The
tension on the folding belt tends to cause the belt to
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want to fold inwardly, but to insure its proper folding
and unfolding, it is essential that the belt have a
transition distance of 7 to 15 times W of tra~el from
the head and tail pulleys. The belt is supported by
troughing idler rolls as needed throughout this
transition length.
A folding belt conveyor system according to this
invention in its preferred embodiment requires head and
tail pulleys that are twice as wide as the systems
idler rolls and a transition area at both head and tail
ends if the loading chute of Figure 6 is not used.
This embodiment of the invention permits an existing
conveyor system to be modified in two ways to provide a
facility in accordance with the instant invention,
namely, the head and tail pulleys of a conventional
conveyor system are replaced with head and tail pulleys
twice as wide and are provided with loading and
unloading transition areas to provide for opening the
belt as it passes over the tail and head pulleys to
permit the belt to be loaded and unloaded.
Alternately, the conventional belt system can be
altered by leaving the head and tail pulleys the same,
but modify the idlers to half their original width and
provide transition loading and unloading areas.
Naturally the preferred modification is where the head
and tail pulle~s are enlarged as in the first
modification, but the second modification would be
desirable where space limitations makes providing the
wider heads and tail pulleys undesirable.
Referring to Figures 2 and 3, to insure proper
folding and unfolding of the belt, idler rolls 14 and
troughing idler rollers 32 may be positioned in the
transition length to aid in the support of the open
belt. Closing rollers 33 may be placed along the
closed portion of the folding belt to aid in keeping
the belt closed and especially is this desirable on
steep grades of 30 to 45 or more such as where the
conveyor is operating in an open pit mine or on a grain
elevator.
The nature of the transition area is more clearly
shown in Figure 5. The terminal roll either head 13 or
tail 12 has the belt passing around it in the unfolded
or flat position 34 showing the flaps 35 unfolded about
fold lines 30 to rest in contact with the surface 36 of
the respec~ive head or tail pulleys. ~s indicated
before the tension applied to the belt in the
tr~nsition area and construction of the belt with fold
lines causes the belt as it moves toward the head or
tail roll to open as shown in Figure 5 where the belt
moves from the fully closed position 37 to the ~ully
open position. Then as the belt passes the head roll
13 and losses its load of bulk material it slowly
closes to present the fully closed position 39 on the
return run.
Sometimes for space limitation, it is desirable
not to open the belt on the tail or loading end. In
this case the tail end roll is only the width "w" of
the belt and the belt is run closed as shown in Figure
6. In this case a loading chute 40 is positioned
inside the belt to force it open as the belt moves pass
the chute and thus the belt is loaded as the material
drops down the chute. I discovered that this
embodiment operates best where there is a transition
length or zone surrounding the chute. Best results are
obtained when the chute is placed about the midpoint of
the transition length which is 7 to 15 times the width
of the belt.
In general, the conveyor system of this invention
will be about 250 to 1000 or more meters; and will
permit ~reater loads to be carried on the belt as
illustrated by Figure 4 where numeral 41 indica-tes the
maximum load carrying capacity of a c~nventional belt
and numerals 42 and 43 respectively designate the
minimum and maximum capacities of the folding belt of
this invention. For these greater loads the drive
systems of the belt must be sufficient to handle the
increased load and speed of the belt. The drive
system, motors, etc., are well known and need no
description to those skilled in the conveyor belt art
or how to calculate required power for the loads to be
handled.
Although this invention has been described in
straight runs, those of ordinary skill readily
appreciates that the system could be operated around
curves with properly banked lateral turns. Likewise,
where steep angle conveying is desired the usual
devices such as cover belts, hugger belts, rubber
covered drums or rolls, terra-tires, etc., may be used,
but for normal operations they are not essential.
A belt especially useful in this invention such as
a conventional belt plied up of conventional rubbers
such as a sulfur carbon b~ack butadiene styrene or
butadiene acrylonitrile rubber was cured preferably at
elevated temperature, about 40C - 190C, 40 - 60% and
preferably to about 30-40% of its cure in the flat
unfolded open position with longitudinal hinge areas
molded into the belt as shown by lines 44 of Figure 8.
Then the areas were formed by folding the flaps 46 over
to bring the edges in to the laid over position 48. A
shim or a flat strip of steel (not shown) may be used
during the initial molding step to aid in folding the
edges over and forming a straight grooved fold line
longitudinally of the belt. The press is closed on the
folded belt and the cure finished at elevated
temperature to give a fully cured folded belt of Figure
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8. It is preferred that the flags 46 in the laid over
position have their ends 47 lap over so the conveyor is
completely closed. Talc and related mold releases may
be used to prevent sticking to the mold or the rubber
sticking to itself. A belt made as above was
vulcanized spliced to give a continuous belt which was
tested on the Herman Morse belt tester for the
equivalent of 486 hours at a speed of about 800 meters
per minute with the flaps open at the head pulley, but
closed at the tail pulley analogous to the embodiment
of Figure 6. Normal test conditions on the Herman
~iorse belt tester is 500 hours at 800 meters per
minute. This embodiment performed satisfactory on the
Herman Morse belt tester. It was observed during the
test runs that the use of a silicone oil lubricant on
the edges of the flaps reduce belt wear. Also, the
test belt could be used for much longer runs as there
was no evidence of belt failure.
A fully cured conventional rubber multiple plied
up coal belt, i.e. a sulfur cured natural rubber fabric
belt was grooved by slitting longitudinally through the
first l~yer of rubber to form two parallel axial fold
lines 47. Then the rubber was removed through the
first layer or ply to give a fold line area about 2.5
centimeters wide, and two plys thick. It was removed
preferably by pulling the cut strip away or by abrading
away with an abrader. Multiple plied belts should be
reduced to two plys in the hinge area for preferred
embodiments. This cut grooved belt was run on the
Herman Morse belt tester and was found to give
satisfactory service when operated according to this
invention.
Another suitable embodiment is a hinge groove
~hich is molded into the belt cover during cure. The
! 35 key to this technique is to use a suitably shaped
molding device which displaces enough of the
conventional multiple ply belts top cover and
compresses the multiple plied belt constructions so as
to form a preferentially flexible, grooved hinge area,
preferably about 1-4 cm. wide and 0.1-2 cm. deep.
Alternatively, this technique may be utilized by
partially curing the belt with the molded groove hinges
and then folding the partially cured belt at the hinges
and finishing the cure while folded. This provides a
fold belt with self closing hinged cover flaps as shown
in Figure 8 usually of at least one-half w in width.
The fold belt will, for most services, be returned with
the cover flaps closed to provide a clean return,
minimize idler wear, and minimize the width of the
return idlers and the conveying structure. The fold
belt can be driven and/or run on pulleys with the flaps
in the fully open, flat position (preferred), or with
the flaps in the fully closed position folded over, on
top of the fold belt as it goes around a pulley, but
never in the fully closed position, folded under, on
the bottom of the fold belt as it goes around a pulley.
While certain representative embodiments and
details have been shown for the purpose of illustrating
the invention, it will be apparent to those skilled in
this art that various changes and modifications may be
made therein without departing from the scope of the
invention.
