Note: Descriptions are shown in the official language in which they were submitted.
10~300~5
The invention relates to a curved belt conveyor, comprising
a circular ring shaped rubber conveyor belt which revolves
between two conical return cylinders and is supported at its
lnterior, shorter longltudinal edge or inner edge at a series
Or rotatable guide rolls, each capable of limited displacement
approximately in radial direction of the curve through which
the conveyor belt moves.
! As is well known, radial forces act on the conveyor belt of
a curved belt conveyor in accordance wlth the respective
construction, These radial forces must be accommodated in suitable
manner.Besides a take-up of force~ at the outer, longer
longitudinal edge of the conveyor belt it has become customary
to transfer these forces at the inner side , i.~. to
support the conveyor belt at the shorter inner ed~e by a guide
means adapted to the curve through which the conveyor belt
moves. The conveyor belts provided for such inner take-up,as
a rule,are relnforced in transverse direction, for example by
means of transverse members embedded in the conveyor belt so
;as to prevent it from warping up in transverse direction. The
radial forces acting between the inner ed~e and the side guide
m~eans result in heavy stressing of the inner edge which is
susceptible to wear. The less uniform the radial forces in the
conYeyor belt aro distributed along the lateral guide means,
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the more 8e~0US the stressing and wear become.
In a known curved belt conveyor of the kind initially mentioned
local peaks of radial forces are reduced by a design according
to which guide rolls constituting the lateral ~uide means are
rotatably supported in pairs each at the two ends of a rocking
arm adapted to swing around its center. Although this provides
for certain adaptation of the lateral guide means or its guide
rolls to the instantaneous geometry of the conveyor belt subjected
to constant variations in operation, the degree thereof is very
limited only ~ecause the radial displacement of one guide roll
of neoessity causes the opposed radial displacement of the other
guide roll supported on ths same rocking arm. ~esides, an exact
fundamental adjustment of the individual guide rolls with respect
to the conveyor belt is required, and eccentric members are
provided for this purpose. However, as the conveyor belt ~radually
changes in dimension, mainly in length during its operational
lifetime because of its natural extension caused by the belt
bias as well as by aging and finally also by its loading, the
basic adjustment should be renewed regularly in accordance with
the changing operating conditions. Yet this cannot be realized
at justifiable maintenance cost and, besides, it would often
require greater adjustibility than the eccentric members offer.
Somewhat better adaptability to the conveyor belt is afforded
by a likewise known further development of the curved belt
conveyor mentioned above. In accordance with this known design
- two rocking arms with guide rolls are suspended for pivoting
movement at the ends of another rocking arm~ This kind of
suspension continues in the form of a Christmas tree until a
~ single ultimate rocking arm is reached. Yet again the prevention
`~ 30 of at least the highest peaks of radial forces requires that the
rocking arm system be adjusted accurately in accordance with the
operating conditions to be expected and the radial forces occurring.
W~th improper adjustment and maintenance uncontrollable high peak
loads at the inr.er edge of the conveyor belt leading to premature
wear can be avoided just as little as with the other known curved
belt conveyor.
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It i8 therefore the object of the invention to provide a curved
belt conveyor with inner accommodation of the radial forces at
a lateral guide means, positively avoiding local high peak values
of the radial forces as well as the necessity of accurate adjust-
ment and constant maintenance.
Starting from a curved belt conveyor of the kind initially mentioned
this object is met, in accordance with the invention, in that the
guide rolls which are adapted to be displaced individually are
biased by ~pring means in a direction toward the conveyor belt.
With the curved belt conveyor according to the invention all
guide rolls are suspended individually, i.eO independently of
each other so as to be displaceable in radial direction. Thus,
ln contrast to the known curved belt conveyors there i6 no
coupling of movement between lndividual guide rolls~ This suspension
of the guide rolls in combination with the spring bias of the
guide rolls in a direction toward the conveyor belt makes it
possible for each individual guide roll to adjusta~omatically
according to the instantaneous geometry of the conveyor belt and
thus achieve optimum adaptation to the respective radial forces
in the sense that the radial forces are always distributed
substantially evenly to several guide rolls. In other words,
the individual guide rolls can give way under the influence of
locally increased radial forces until the adjacent guide rolls
take a greater share in the support, and vice versa~ Undue
contact pressure of the conveyor belt inner edge which is
susceptible to wear against individual guide rolls and in-
; admissibly strongkneading of the inner edge resulting fromsuch contact pressure thus are effectively avoided. The lifetime
of the inner edge and consequently of the entire rather
expensive circular ring shaped conveyor belt, therefore, is
much longer than that of known curved belt conveyors~ Another
essential advantage of the curved belt conveyor according to
the invention resides in the self-centering capacity of the
conveyor belt. Once the resilience, in other words the forces
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exerted by the spring means have been selected correctly, the
conveyor belt is always held automatically in a certain part
circular Fath~ at an equilibrium between the spring forces and
the radial forces originating from the longitudinal tensioning
of the conveyor beltO This is true even if the dimensions, in
particular the length of the conveyor belt change during the
operational life. Thus expensive adjustment manipulation and
considerable maintenance work can be dispensed with.
The self-centering of the conveyor belt is especially accurate
if the bias produced by the spring means increases in the
direction of movement of the conveyor beltO This allows for the
fact that the radial forces of a conveyor belt in operation
rise progressively from the driven return cylinder or drum
in the direction of movement. Yet a relatively coarse adjustment
of the bias ~alues is quite sufficient. For example, all guide
rolls of th~e/run of the conveYor belt in the flrst half of the
conveying distance may be ad~usted to a certain bias which is
the same for all of them, and all guide rolls in the second half
of the conveying distance may be ad~usted to a higher bias which
again ls the same for all of them. With curved belt conveyors
of medium size and load the required resilience values lie in a
range from 5 to 10 kp (49.03 to 98007 N). Then the initial
resilience selected for the first half of the conveying distance,
for example, may be 5 kp (49003 N), and in the second half the
i~itial resilience, for example, may be 7 kp (68.65 N)o
The term spring means is understood to be very broad. It is to
comprise not only the normal mechanical springs, such as leaf
springs, spiral springs, helical springs, and the like but also
hydraulic or pneumatic spring means comprising working cylinders
for instance. However, in the interest of obtaining a simple
structure mechanical springs are preferred.
A convenient structural embodiment of the novel curved belt
conveyor comprising a mechanical spring ls charact,erized in that
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each guide roll is rotatably supported at the free end of a
of its own
swinging leverrwhich is engaged by a biased spring. Further
simplification can be obtained by providing or.e biased spring
for two ad~acent guide rolls each, th;s spring being tensioned
between their two sw~ging levers. True9 with the lat~er design
a certain elastic coupling of the two guide rolls cy way of the
common spring must be put up with. Yet in most cases it should
be meaningless for the effect aimed at by the invention.
In another convenient structural embodiment of the novel curved
belt conveyor two adjacent guide rolls each are rotatably
supported at both ends of a leaf spring which is held stationarily
in its center. This has the a~vantage that a single structural
element, namely the leaf spring serves to suspend as well as to
bias the guide rolls. Also in a third embodiment of the novel
curved belt conveyor a spring means each per guide roll serves
to achieve the suspen8ion as well as bias of the ~uide roll.
Moreover, thls embodlment 18 characterized by a particularly
space-saving structure. Its characteristic feature resides in
the fact that each guide roll is rotatably supported on a race
which is carried by the spring means disposed inside the race.
The spring means in this case, of course9 is so designed and
arranged that it holds the corresponding guide roll practically
immovable in axial direction, whereas it permits radial
displacement of the guide roll in its plane~ in accordance with
the balance of power between the radial force of the conveyor
belt and the bias of the spring means. The spring means pre-
ferably is a leaf spring or a shaped rubber body. In a particular-
ly simple manner the race embodies the inner ring of a ball
`bearmg, on the outer ring of which, for example~ a flanged ring
is fitted to constitute the guide roll.
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The present invention is directed to a curved
conveyor having a generally planar ring shaped belt, and means
for supporting the belt and for guiding the belt along a closed
path of travel having first and second generally parallel,
spaced apart runs with an inner peripheral edge of the belt
substantially defining an arc of a circle about a predetermined
center. The supporting and guiding means comprises a plurality
of guide roller means for engaging the inner peripheral edge of
the belt, means mounting the roller means adjacent the arc and
for individual independent movement radially of the arc, and
means operatively connected with the mounting means and the
roller means for resiliently biasing each of the roller means
radially outwardly against the edge of the belt.
In the invention described the conveyor further
comprises means operatively connected with the supporting and
guiding means for driving the belt in movement in a predetermined
direction along the runs, wherein the means for resiliently
biasing the roller means imposes bias forces which increase in
the direction of movement of the belt.
The means for resiliently biasing the roller means
; may comprise a plurality of pivoting lever means corresponding
in number to the number of roller means, each lever means
rotatably supporting a corresponding one roller means, and a
plurality of spring means operatively connected to the lever
means for imposing biasing forces thereon. Alternatively, the
spring means may operatively connect a pair of the lever means
for imposing biasing forces on a corresponding pair of the
roller means.
According to another aspect of the invention, the
means for resiliently biasing the roller means comprises a
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plurality of leaf spring means, each having spaced end portions
for rotatably supporting an adjacent pair of the roller means,
and means for stationarily supporting each of the leaf spring
means at points thereof intermediate the end portions.
In the invention described, the means for resiliently
biasing the roller means may comprise a plurality of race
means, corresponding in number to the number of roller means,
each race means rotatably supporting a corresponding one
roller means, and a plurality of spring means corresponding
in number to the number of race means, each spring means being
disposed within a corresponding one race means. The spring
means may comprise a metallic leaf spring member, or a shaped
elastomeric material member, and each race means may comprise
an inner race of an anti-friction bearing means.
The invention and further advantageous details
thereof will be described belo~, by way of example, with
reference to the accompanying diagrammatic drawings in which
several embodiments are shown and in which:
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~lg~ 1 ls an isometric view of a curved belt conveyor in
~reatly simplified illustration,
fig. 2 is an isometric view of two guide rolls and their
suspension as used in the curved belt conveyor shown
i~ fig. 1,
fig. 3 is an isometric view of two guide rolls with a different
kind of suspension for a curved belt conveyor,
fig. 4 is an isometric view of guide rolls and yet another type
of suspension for a curved belt conveyor,
fig. 5 is an isometric view of a guide roll with integrated
suspension for a curved belt conveyor,
flg. 6 is an isometri¢ view of a guide roll with a different
kind of integrated suspension for a curved belt conveyor.
As shown in fig. 1, a curved belt conveyor comprises an endless,
closed rub~er conveyor belt 1 of oonvent~onal design made in
circular ring shape and revolvlng between two conical return
cylinders 2 and 3. The axes of rotation of the two return
cyllnders disposed in a common plane extend at a certain angle
with respect to each other in accordance with the curve through
which the conveyor belt 1 has to move. The front ends of the
two return cylinders which are visible in fig. 1 and located
at the smaller radius are facing inwardly, i.e. toward the
imagined center of curvature of the curve. The right return
`~ ~ cylinder 3, as seen in fig. 1, is driven and moves conveyor
belt 1 in the direction of movement indicated by arrow 4. Trans-
verse reinforcement of the oonveyor belt 1 is obtained by
; radially oriented bars (not shown) which are embedded in the
~conveyor ~elt. The inner edge 5, i.e. the interior, shorter
; longitudir~l edge of conveyor belt 1 is provided with ed~e
`30 ~ protection in the form of a partlcularly wear-resistant and
abrasion-proo~ rubber.
Lateral guide means 8 and 9 cooperating with the inner edge 5
are assoc~s~ed with the upper run 6 of the conveyor belt 1
destined to convey goods and with the lower run 7~ respectively.
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They serve to accommodate or take up the lnwardly directed
radial forces acting on the conveyor belt, i.e. to support
belt 1 with respect to these radial forces. Both lateral guide
means extend practically across the entire distance between the
two return cylinders 2 and 3 and are of identical design. They
each comprise a series o~ identical flanged guide rolls 10
havingrotation~pi~ ght angles to the plane of the
conveyor belt and being arranged spaced apart at the inner edge 5
of the aonveyor belt in a normal position along a curved
path around the center of curvature, the flanges 12 of said
guide ~olls projecting over the inner edge 5.
For purposes of suspension of the guide rolls 10 a straight,
one-arm swinging lever 13 is associated with each guide roll.
The axle 11 of the respective guide roll is fixed to the
free end Or the swinging lever 13 so that the axis Or rotation
extends in vertical direction with respect to the swinging plane.
In a guide means the two swinging levers 13 of two adjacent
guide rolls 10 each have a common swivel pin 14 which is located
between the two guide rolls approximately on their interconnecting
line and held stationary in a manner not shown in detail. By
virtu~e o~ this arrangement each guide roll is adapted to be
displaced back and forth individually transversely Or the axis
of rotation by swinging movement Or its swinging lever, regard-
less of the other guide rolls. This diSplacement is effected ,
within a limited swinging range, practically in radial direction
of the curve through which the conveyor belt moves.
The axle 11 of each guide roll 10 has an extension 15
passing downwardly through the swinging lever 13 and provided
near its end with an annular groove 16~ A helical spring 17 is
clamped in the annular groove 16 and biased in radial direction
between the extension and a stationary means (not shown) below
the conveyor belt 1 so as to pull the associated guide roll 10
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at a certain bias in a direction toward the conveyor belt.
The helical springs 17 whioh are coordinated with the guide rolls
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of the upper run 6 are dimensioned differently so that, in
normal position~ the guide rolls 10 of the first half of the
conveying distance between return cylinder 2 and approximately
the midpoint of the curved belt conveyor are each biased at a
resilience of 5 kp (= 49.03 N), while the guide rolls in the
second half of the conveying path are each biased at a resilience
of 7 kp (= 68.65 N). The guide rolls of the lower run 7 are
biased lln~formly at a resilienoe of 5 kp (= 49.03 N). Between
the te~sioned conveyor belt 1 which is subjected to driving
forces during operation and which the radial forces tend to
pull inwardly and the biased guide rolls 10 a balance of forces
is establishedO Thus the oonveyor belt is automatically held in
a part circular path and the radial forces taken up are distributed
substa~tially evenly among the indi~idual guide rolls 10.
A modifled suspension of the ~uide rolls 10, as shown in fig. 3,
comprises an angular,two-arm swinging lever 23 mounted for
.. plvoting movement around a stationary pivot pin ~4 by means of
a bushing 25. In normal position one arm 28 of æwinging lever
23 extends approximately parallel to the inner edge 5 of the
. 20 conveyor belt 1. At its end the arm 28 carries the axle 11
of its asæociated guide roll 10. The other arm 29 extends
radially inwards in a direction toward the center of curvature
approximately at right angles to arm 28. At itæ free end the
arm 29 is provided with a hole 26 ln which one end of a helical
spring 27 is hooked. The other end of helical æpring 27 is hooked
in a hole 26' in swinging lever 23' of the adjacent guide roll 10.
. Swinging lever 23' is designed and arranged in mirror æymmetry
with respect to swinging lever 23 such that the helical spring
27 which is tenæioned between the two æwinging leveræ presses
the two guide rollæ 10 carried by the æwinging levers against
: : the inner edge 5 of the ¢onveyor belt 1.
Fig. 4 shows another embodlment of the suspe~sion of the guide
rolls for the upper run 6 and the lower run 7 of the conveyor
belt 1. Four guide rolls 10 each, two for the upper and two for
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the lower run are held in common by a U-shaped stationary
bracket 33. In planes somewhat lower than the corresponding
plane of the conveyor belt the two legs 34 of the bracket 33
each extend in radial direction up to the inner edge 5 of the
conveyor belt lo A clamping piece 35 is fastened by a screw
connection to each leg 34. An oblong hole 36 permits adjustment
of clamping piece 35 in radial direction and fixation by way of
tighte~i~g the screw connection.
A leaf spring 37 is welded in the middle to the front end of
clamping piece 35 facing the inner edge 5. The plane of the
undulated leaf spring 37 extends vertically to the plane of the
conveyor belt. ~he leaf spring 37 has two arms 38 which are
similar in mirror symmetry, extend next to the inner edge 5,
and have two one-piece lugs 39 ea¢h at their free ends bent at
right angles and retainlng the plvot pln 31 which projects at
elther end from the respective guide roll lO. The guide rolls
lO are pressed against the inner edge 5 of the conveyor belt 1
by the leaf springs 37 and their respective arms 38, the bias
or resilience being adjustable by corresponding adjustment of
the Flamping piece 35.
Fig. 5 illustrates a guide roll 4O with integrated suspension
suitable to constitute guide means 8 or 9. The guide roll 4O is
supported for rotation on a race 41 constituting the inner ring
of a ball bearing. A flanged ring 42 is secured against rotation
on the outer ring 44 of the ball bearing 43 and, together with
the outer ring 44, forms the guide roll proper.
The race 41 is carried by a leaf spring 47, the plane of which
is oriented in vertical direction with respect to the plane of
the conveyor belt and which is undulated transversely of its
own plane, as is tha case with leaf spring 37 of the preceding
embodiment. In a central section 45 the leaf spring 47 is bent
in U-shape to form a slot ~Jhich receives a screw 4~ to clamp
the leaf spring 47 to a stationary mounting means (not shown).
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At either side of section 45 the leaf spring 47 has two arms 48
which are s~m11ar in mirror symmetry and each provided at the
free end with a connecting piece 49. The connecting pieces 49
abut against the inside of race 41 and are immovable relative to
the ~ame. The arms 48 of leaf spring 47 extend approximately
parallel to the inner edge 5 of conveyor belt 1, and with this
disposition the slot formed by section 45 extends approximately
in radial direction. The bias at which the leaf spring 47 presses
the guide roll 40 against the conveyor belt 1 can be adjusted
by displ~cing the leaf spring along the slot with respect to
screw 46.
Fig. 6 shows a modification of the previous embodiment in which
the same guide roll 40 is suspended by means of a shaped rubber
body 57 taking the place of leaf spring 47. The rubber body 57
has a central clamplng seatlon 55 which iB reinrorced in axlal
dire¢tion of the gulde roll and has a radially or1ented oblong
hole 56 serving to receive a clamping screw (not shown) for
stationary fixing of the shaped rubber body. At either side of
the clamping section 55 the shaped rubber body has a waist-like
spring section 58. At their ends the spr~ng sections 58 are
enlarged to form a connecting section 59 each. Each connecting
sect~on 59 is cemented at its front end face to the inner surface
~; of race 41. Because of its conf~guration the shaped rubber body
57 yields relatively little in axial direction of the guide roll
40, in other words transversely of the plane of the conveyor belt.
Yet by lateral deformation of its waist-like spring sections 58
it permits displacement of the guide roll 40 in radial direction
~of the curved belt conveyor.
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; By mounting on a suitable supporting system guide rolls 4O
as wel} as guide rolls lo can be used to form two lateral
gulde means 8 and 9 cooperating with the inner edge 5 of the
conveyor beltjl, as shown in fig~ 1. It is likewise possible
to apply the measures explained above with regard to the ad-
justment of the spring bias.
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