CA1093005A

CA1093005A - Curved belt conveyor

Info

Publication number: CA1093005A
Application number: CA303,399A
Authority: CA
Inventors: Heinz Gerdes; Karl-Gunther Blattermann
Original assignee: Conrad Scholtz AG
Current assignee: Conrad Scholtz AG
Priority date: 1977-05-21
Filing date: 1978-05-16
Publication date: 1981-01-06
Also published as: DE2723033B1; IT1094568B; IT7821795V0; DE2723033C2; GB1601037A; IT7823194A0; JPS5417283A

Abstract

A B S T R A C T

A curved belt conveyer in which all of the lateral guide rolls are suspended individually and biased by spring means in a direction towards the conveyor belt.
Individual spring biasing of the lateral guide rolls tends to avoid coupling of movement between individual guide rolls and each guide roll can adjust automatically according to the instantaneous geometry of the conveyor belt. This in turn avoids the necessity of previously known designs to adjust the guide rolls frequently to meet gradual changes in dimensions of the belt.

Description

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, ~ . .

:
, ,, `~3~,~V

: ~ .
.

10~.~3005 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.

' ~o9~oos 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 .

~, .. .,, ~ .. ,.. . . ., ., . . ............ , - , .

10~9~005 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 . .

~093005 - S~

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.

~.

~0~3U05 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 - 5a -10~3005 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:

~i' - 5b -10~3005 _ 6 --~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.

10~3005 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 . .
at a certain bias in a direction toward the conveyor belt.

The helical springs 17 whioh are coordinated with the guide rolls ~093005 _ 8 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 10~30~5 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).

.

,,,, , ~ , .
.

~0930~S

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.
::
~,, ,~, ; 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.
_ . .. .

.
~ .. -. ~ .

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. 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, said supporting and guiding means comprising a plurality of guide roller means for engaging said inner peripheral edge of said belt, means mounting said roller means adjacent said arc and for individual independent movement radially of said arc, and means operatively connected with said mounting means and said roller means for resiliently biasing each of said roller means radially outwardly against said edge of said belt, wherein said means for resiliently biasing said roller means comprises a plurality of pivoting lever means corresponding in number to the number of said roller means, each said lever means rotatably supporting a corresponding one roller means, and a plurality of spring means operatively connected to said lever means for imposing biasing forces thereon.

2. A conveyor according to claim 1, further comprising means operatively connected with said supporting and guiding means for driving said belt in movement in a predeter-mined direction along said runs, and further wherein said means for resiliently biasing said roller means imposes bias forces which increase in said direction of movement of said belt.

- Page 1 of Claims -

3. A conveyor according to claim 1, wherein said means for resiliently biasing said roller means comprises a plurality of pivoting lever means corresponding in number to the number of said roller means, each said lever means rotata-bly supporting a corresponding one roller means and a plurality of spring means operatively connected to said lever means wherein each of said spring means operatively connects a pair of said lever means for imposing biasing forces on a corresponding pair of said roller means.

4. A conveyor according to claim 3, further comprising means operatively connected with said supporting and guiding means for driving said belt in movement in a predeter-mined direction along said runs, and further wherein said means for resiliently biasing said roller means imposes bias forces which increase in said direction of movement of said belt.

5. A conveyor according to claim 1, wherein said means for resiliently biasing said roller means comprises a plurality of leaf spring means, each said leaf spring means having spaced end portions for rotatably supporting an adjacent pair of said roller means, and means for stationarily supporting each of said leaf spring means at points thereof intermediate said end portions.

6. A conveyor according to claim 5, further comprising means operatively connected with said supporting and guiding means for driving said belt in movement in a predeter-mined direction along said runs, and further wherein said means for resiliently biasing said roller means imposes bias forces which increase in said direction of movement of said belt.

- Page 2 of Claims -

7. A conveyor according to claim 1, wherein said means for resiliently biasing said roller means comprises a plurality of race means, corresponding in number to the number of said roller means, each said race means rotatably supporting a corresponding one roller means, and a plurality of spring means corresponding in number to the number of said race means, each said spring means being disposed within a corresponding one race means.

8. A conveyor according to claim 7, further comprising means operatively connected with said supporting and guiding means for driving said belt in movement in a predeter-mined direction along said runs, and further wherein said means for resiliently biasing said roller means imposes bias forces which increase in said direction of movement of said belt.

9. A conveyor according to claim 7, wherein each said spring means comprises a metallic leaf spring member.

10. A conveyor according to claim 7, wherein each said spring means comprises a shaped elastomeric material member.

11. A conveyor according to claim 7, wherein each said race means comprises an inner race of an anti-friction bearing means.

- Page 3 of Claims -