GB1601037A

GB1601037A - Curved belt conveyor

Info

Publication number: GB1601037A
Application number: GB20926/78A
Authority: GB
Original assignee: Conrad Scholtz AG
Current assignee: Conrad Scholtz AG
Priority date: 1977-05-21
Filing date: 1978-05-19
Publication date: 1981-10-21
Also published as: JPS5417283A; DE2723033B1; IT1094568B; DE2723033C2; IT7821795V0; IT7823194A0; CA1093005A

Description

(54) CURVED BELT CONVEYOR (71) We, CONRAD SCHOLTZ AG, a German body corporate, of Am Stadtrand 55-59, 2000 Hamburg 70, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 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 interior, shorter longitudinal edge or inner edge by a series of rotatable guide rolls, each capable of limited displacement in a direction approximately radially 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 with the respective construction.

These radial forces must be accommodated in suitable manner. Besides a take-up of forces at the outer, longer longitudinal edge of the conveyor belt it has become customary to transfer these forces at the inner side, i.e. to support the conveyor belt at the shorter inner edge 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 reinforced in a 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 edge and the side guide means result in heavy stressing of the inner edge which is susceptible to wear. The less uniform the radial forces in the conveyor belt are distributed along the lateral guide means, the more serious 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 guide 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 because the radial displacement of one guide roll of necessity causes the opposed radial displacement of the other guide roll supported on the same rocking arm. Besides, 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 gradually 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 condition. Yet this cannot be realized at justifiable maintenance cost and, besides, it would often require greater adjustability 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 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. With improper adjustment and maintenance, un controllable high peak loads at the inner edge of the conveyor belt leading to premature wear can be avoided just as little as with the other known curved belt conveyor.

It is 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 adjustment and constant maintenance.

According to the present invention, there is provided a curved belt conveyor, comprising a generally circular ring-shaped conveyor belt which travels between two generally conical return members and is supported at its inner, shorter longitudinal edge by a series of rotatable guide rolls capable of limited displacement in an approximately radial direction with respect to the curve through which the conveyor belt moves, the guide rolls being adapted to be displaced individually and being biased by spring means in a direction toward the conveyor belt.

With the curved belt conveyor according to the invention all guide rolls are suspended individually, i.e. independently of each other so as to be displaceable in radial direction.

Thus, in contrast to the known curved belt conveyors, there is no coupling of movement between individual 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 adjust automatically 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 inadmissibly strong kneading of the inner edge resulting from such contact pressure, are thus 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 exerted by the spring means have been selected correctly, the conveyor belt is always held automatically in a certain part circular path, at an equilibrium between the spring forces and the radial forces originating from the longitudinal tensioning of the conveyor belt. 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 belt. 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 values is quite sufficient. For example, all guide rolls of the conveying run of the conveyor belt in the first half of the conveying distance may be adjusted 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 adjusted to a higher bias which again is 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 98.07 N).Then the initial resilience selected for the first half of the conveying distance, for example, may be 5 kp (49.03 N) and in the second half the initial resilience, for example, may be 7 kp (68.65 N).

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 is characterized in that each guide roll is rotatably supported at the free end of its own swinging lever which is engaged by a biased spring. Further simplification can be obtained by providing one biased spring for each two adjacent guide rolls, this spring being tensioned between their two swinging levers. True, with the latter design a certain elastic coupling of the two guide rolls by 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 advantage 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, an individual spring means for each guide roll serves to achieve the suspension as well as bias of the guide roll. Moreover, this embodiment is 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 course, is so designed and arranged that it holds the corresponding guide roll practically immovable in an 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 preferably is a leaf spring or a shaped rubber body. In a particularly simple manner the race embodies the inner ring of a ball bearing, on the outer ring of which, for example, a flanged ring is fitted to constitute the guide roll.

The invention and further advantageous details thereof will be described below, by way of example, with reference to the accompanying diagrammatic drawings in which several embodiments are shown and in which: Fig. 1 is an isometric view of a curved belt conveyor in greatly simplified illustration, Fig. 2 is an isometric view of two guide rolls and their suspension as used in the curved belt conveyor shown in 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, Fig. 6 is an isometric 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 rubber conveyor belt 1 of conventional design made in circular ring shape and revolving between two conical return cylinders 2 and 3. The axes of rotation of the two return cylinders are disposed in a common plane and 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. Transverse reinforcement of the conveyor belt 1 is obtained by radially oriented bars (not shown) which are embedded in the conveyor belt. The inner edge 5, i.e. the interior, shorter longitudinal edge of conveyor belt 1 is provided with edge protection in the form of a particularly wear-resistant and abrasionproof rubber.

Lateral guide means 8 and 9 cooperating with the inner edge 5 are associated with the upper run 6 of the conveyor belt 1 destined to convey goods, and with the lower run 7, respectively.

They serve to accommodate or take up the inwardly 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 of identical flanged guide rolls 10 rotatably mounted on pins or axles 11 at right angles to the plane of the conveyor belt and being arranged spaced apart at the inner edge 5 of the conveyor belt in a normal position along a curved path around the center of curvature, the flanges 12 of said guide rolls 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 of the swinging lever 13 so that the axis of rotation extends in a vertical direction with respect to the swinging plane. The two swinging levers 13 of each two adjacent guide rolls 10 are mounted on a common swivel pin 14 which is located between the two guide rolls approximately on their interconnecting line, and is held stationary in a manner not shown in detail. By virtue of this arrangement, each guide roll is adapted to be displaced back and forth individually, transversely of the axis of rotation, by swinging movement of its swinging lever, regardless of the other guide rolls.

This displacement is effected, within a limited swinging range, practically in the radial direction of the curve through which the conveyor belt moves.

As shown in fig. 2, 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 with a certain bias in a direction toward the conveyor belt.

The helical springs 17 which are coordinated with the guide rolls of the upper run 6 are dimensioned differently so that, in a 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 with a resilience of 5 kp (= 49.03 N), while the guide rolls in the second half of the conveying path are each biased with a resilience of 7 kp (= 68.65 N): The guide rolls of the lower run 7 are biased uniformly with a resilience of 5 kp (= 49.03 N). During operation, the tensioned conveyor belt 1 is subjected to driving forces which include radial forces tending to pull the belt inwardly, and between the belt and the biased guide rolls 10 a balance of forces is established.Thus the conveyor belt is automatically held in a part circular path and the radial forces taken up are distributed substantially evenly among the individually guide rolls 10.

A modified suspension of the guide rolls 10, as shown in fig. 3, comprises an angular, twoarm swinging lever 23 mounted for pivoting movement around a stationary pivot pin 24 by means of a bushing 25. In a normal position, one arm 28 of swinging lever 23 extends approximately parallel to the inner edge 5 of the conveyor belt 1. At its end, the arm 28 carries the axle 11 of its associated 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 its free end, the arm 29 is provided with a hole 26 in which one end of a helical spring 27 is hooked. The other end of helical spring 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 symmetry with respect to swinging lever 23 such that the helical spring 27 which is tensioned between the two swinging levers presses the two guide rolls 10 carried by the swinging levers against the inner edge 5 of the conveyor belt 1.

Fig. 4 shows another embodiment of the suspension of the guide rolls for the upper run 6 and the lower run 7 of the conveyor belt 1.

The guide rolls 10 are disposed in group of four, two guide rolls for the upper and two for the lower run, held by a common U-shaped stationary bracket 33. In planes somewhat lower than the corresponding plane of the conveyor belt, two legs 34 of the bracket 33 each extend in a radial direction up to the inner edge 5 of the conveyor belt 1. 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 a radial direction and fixation by way of tightening 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. The 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 at each of their free ends bent at right angles and retaining the pivot pin 31 which projects at either end from the respective guide roll 10. The guide rolls 10 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 clamping piece 35.

Fig. 5 illustrates a guide roll 40 with integrated suspension suitable to constitute guide means 8 or 9. The guide roll 40 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 the case with leaf spring 37 of the preceding embodiment. In a central section 45 the leaf spring 47 is bent in Ushape to form a slot which receives a screw 46 to clamp the leaf spring 47 to a stationary mounting means (not shown).

At either side of section 45 the leaf spring 47 has two arms 48 which are similar in mirror symmetry, each provided at its free end with a connecting piece 49. The connecting pieces 49 abut against the inside of race 41 and are immovable relative to the same. 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 a radial direction.

The bias with which the leaf spring 47 presses the guide roll 40 against the conveyor belt 1 can be adjusted by displacing 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 clamping section 55 which is reinforced in the axial direction of the guide roll and has a radially oriented 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 spring sections 58 are enlarged to form a connecting section 59 each.

Each connecting section 59 is cemented at its front end face to the inner surface of race 41.

Because of its configuration 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 a radial direction of the curved belt conveyor.

By mounting on a suitable supporting system, guide rolls 40 as well as guide rolls 10 can be used to form two lateral guide means 8 and 9 cooperating with the inner edge 5 of the conveyor belt 1, as shown in fig. 1. It is likewise possible to apply the measures explained above with regard to the adjustment of the spring bias.

WHAT WE CLAIM IS: 1. A curved belt conveyor, comprising a generally circular ring-shaped conveyor belt which travels between two generally conical return members and is supported at its inner, shorter longitudinal edge by a series of rotatable guide rolls capable of limited displacement in an approximately radial direction with respect to the curve through which the conveyor belt moves, the guide rolls being adapted to be displaced individually and being biased by spring means in a direction toward the conveyor belt.

2. A curved belt conveyor according to claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. approximately parallel to the inner edge 5 of the conveyor belt 1. At its end, the arm 28 carries the axle 11 of its associated 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 its free end, the arm 29 is provided with a hole 26 in which one end of a helical spring 27 is hooked. The other end of helical spring 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 symmetry with respect to swinging lever 23 such that the helical spring 27 which is tensioned between the two swinging levers presses the two guide rolls 10 carried by the swinging levers against the inner edge 5 of the conveyor belt 1. Fig. 4 shows another embodiment of the suspension of the guide rolls for the upper run 6 and the lower run 7 of the conveyor belt 1. The guide rolls 10 are disposed in group of four, two guide rolls for the upper and two for the lower run, held by a common U-shaped stationary bracket 33. In planes somewhat lower than the corresponding plane of the conveyor belt, two legs 34 of the bracket 33 each extend in a radial direction up to the inner edge 5 of the conveyor belt 1. 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 a radial direction and fixation by way of tightening 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. The 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 at each of their free ends bent at right angles and retaining the pivot pin 31 which projects at either end from the respective guide roll 10. The guide rolls 10 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 clamping piece 35. Fig. 5 illustrates a guide roll 40 with integrated suspension suitable to constitute guide means 8 or 9. The guide roll 40 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 the case with leaf spring 37 of the preceding embodiment. In a central section 45 the leaf spring 47 is bent in Ushape to form a slot which receives a screw 46 to clamp the leaf spring 47 to a stationary mounting means (not shown). At either side of section 45 the leaf spring 47 has two arms 48 which are similar in mirror symmetry, each provided at its free end with a connecting piece 49. The connecting pieces 49 abut against the inside of race 41 and are immovable relative to the same. 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 a radial direction. The bias with which the leaf spring 47 presses the guide roll 40 against the conveyor belt 1 can be adjusted by displacing 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 clamping section 55 which is reinforced in the axial direction of the guide roll and has a radially oriented 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 spring sections 58 are enlarged to form a connecting section 59 each. Each connecting section 59 is cemented at its front end face to the inner surface of race 41. Because of its configuration 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 a radial direction of the curved belt conveyor. By mounting on a suitable supporting system, guide rolls 40 as well as guide rolls 10 can be used to form two lateral guide means 8 and 9 cooperating with the inner edge 5 of the conveyor belt 1, as shown in fig. 1. It is likewise possible to apply the measures explained above with regard to the adjustment of the spring bias. WHAT WE CLAIM IS:

1. A curved belt conveyor, comprising a generally circular ring-shaped conveyor belt which travels between two generally conical return members and is supported at its inner, shorter longitudinal edge by a series of rotatable guide rolls capable of limited displacement in an approximately radial direction with respect to the curve through which the conveyor belt moves, the guide rolls being adapted to be displaced individually and being biased by spring means in a direction toward the conveyor belt.

2. A curved belt conveyor according to claim

1, wherein the bias produced by the spring means increases in the direction of movement of the conveyor belt.

3. A curved belt conveyor according to claim 1 or 2, wherein each guide roll is rotatably supported at the free end of an associated swinging lever which is engaged by spring means comprising a tensioned spring.

4. A curved belt conveyor according to claim 3 wherein the tensioned spring is common to and acts between, the two swinging levers of two adjacent guide rolls.

5. A curved belt conveyor according to claim 1 or 2, wherein the guide rolls are arranged in pairs, the two adjacent guide rolls of each pair being rotatably supported one at each end of a leaf spring which is held stationary at its center.

6. A curved belt conveyor according to claim 1 or 2, wherein each guide roller is rotatably supported by a bearing which is carried by spring means disposed inside the bearing.

7. A curved belt conveyor according to claim 6, wherein the spring means is leaf spring.

8. A curved belt conveyor according to claim 6, wherein the spring means is a shaped body of a natural or synthetic rubber of a synthetic plastics material.

9. A curved belt conveyor according to claim 6, 7, or 8, wherein the bearing is a race formed by the inner ring of a ball bearing.

10. A curved belt conveyor substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

11. A curved belt conveyor substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

12. A curved belt conveyor substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.

13. A curved belt conveyor substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.

14. A curved belt conveyor substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.