WO1987003566A1

WO1987003566A1 - Arrangement in a two-belt conveyor

Info

Publication number: WO1987003566A1
Application number: PCT/SE1986/000553
Authority: WO
Inventors: Jan A^oke Torsten LOODBERG; Arne Evert Wall; Olle Lennart Siwersson
Original assignee: Ab Scaniainventor
Priority date: 1985-12-09
Filing date: 1986-12-04
Publication date: 1987-06-18
Also published as: SE8505792L; SE8505792D0; SE451127B

Abstract

The two belts (1, 2) of a two-belt conveyor are sealed along a part of an endless path of motion at each longitudinal edge of the conveyor by means of two longitudinal belt edge portions (3, 5; 4, 6) contacting one another. Each belt edge portion (3, 5; 4, 6) is provided at each longitudinal edge with a transverse force-absorbing element (15-18) extending along the entire length of the belt and projecting from an adjacent part of the respective belt (1, 2). A plurality of first transverse force members (7, 8; 11, 12) are mounted along the sealed portion in contact with the transverse force-absorbing elements (15-18) for applying a compressive force (P) to the two belt edge portions (3, 5; 4, 6) of each longitudinal edge which are in contact with one another. A plurality of second transverse force members (9, 10; 13, 14) are also mounted along the sealed part in contact with said transverse force-absorbing elements (15-18) for keeping apart the two longitudinal edges of the conveyor against the action of the material conveyed between the belts (1, 2). The transverse force-absorbing elements (15-18) also absorb tensile forces in the longitudinal reaction of the belts (1, 2). Furthermore, the two belt edge portions (3, 5; 4, 6) are bent out at each longitudinal edge from the center plane (M) of the belt conveyor.

Description

ARRANGEMENT IN A TWO-BELT CONVEYOR

The present ^'invention relates to an arrangement in a two-belt conveyor, the two belts of which are sealed along at least a part of an endless path of motion at each longitudinal edge of the conveyor by means of two longitudinal belt edge portions contacting one another.

In prior art belt conveyors of this type, sealing is achieved in that the two longitudinal belt edge portions at each longitudinal edge are held pressed together by various means, for example by application of an excess pressure to the outwardly facing sides of the two belt edge portions contacting one another at each longitudinal edge. It is also known to form the belt edge portions with means engaging one another in such a manner that the belt edge portions are held together.

The prior art solutions to the problem of providing a reliable seal at the longitudinal edge of a belt conveyor suffer from a number of shortcomings. Merely holding the belt edge portions together is difficult, and the seal may easily become inadequate. During its conveyance, the material shifts its position and works it way out toward the longitudinal belt edges. The shifting motion is caused by the varying cross- sectional shape of the channel formed between the belts and is especially pronounced with fine-grained or pulverulent materials in which a hydrostatic pressure prevails. Applying an excess pressure to the outer sides of the belt edge portions also is a highly compli- cated and therefore expensive solution. The provision of various types of engagement means at the belt edge portions causes difficulties when the material is fed onto or discharged from the conveyor in that the conveyed material may get stuck in and jam the engage- ment means, thereby preventing the desired engagement.

The sealing of the longitudinal edge can be improved by providing each longitudinal edge of each of the two belt edge portions with a transverse force-absorbing element which extends along the entire belt length and projects from an adjacent part of the respective belt, and by mounting a plurality of transverse force members along the sealed part in contact with said transverse force-absorbing elements, on the one hand for applying a compressive force to the two belt edge portions of each longitudinal edge which are in con¬ tact with one another and, on the other hand, for keeping apart the two longitudinal edges of the con¬ veyor against the action of the material conveyed between the belts.

It is the object of this invention to establish, in an arrangement of the above-mentioned type, a more reliable sealing of the longitudinal edge, while avoid¬ ing the shortcomings associated with prior art solu- tions.

According to the invention, this object is achieved in that the two belt edge portions at each longitudi¬ nal edge are bent out from the center plane of the belt conveyor. To facilitate the bending-out, each belt edge portion preferably is delimited from the adjoining intermediate portion by means of a longitudi¬ nal bending indication which may be in the form of an insert in the belt or a change in the belt thick¬ ness. The bending-out of the belt edge portions, in accordance with the present invention, makes it possible to establish the requisite seal solely by means of rollers which are distributed along the longitudinal edges and by which the belt edge portions are bent, compressed and kept apart. To further improve the seal, a pressure may be maintained within the belt conveyor which is lower than the outside pressure. A further advantage is obtained if the inner belt edge portion within the bent region is made out¬ wardly spring-biased towards the outer belt edge portion.

The invention will now be described in more detail, reference being had to the accompanying drawings illu- strating examples of embodiments of the invention.

Fig. 1 is a schematic cross-sectional view of a belt conveyor having transverse force-absorbing elements and transverse force members cooperating with said elements. Figs. 2 and 3 illustrate schematically two examples of the practical application of the inven¬ tion in a belt conveyor having two belts and bent belt edge portions. Figs. 4 and 5 illustrate two examples of a practical embodiment of the arrangement according to the invention, having bent belt edge portions. Fig. 6 illustrates a preferred embodiment of a guide roller. Fig. 7 illustrates an example of an alternative embodiment of the belt edge portion of belts that may be used in the arrangement according to the invention. Eig. 1 is a cross-sectional view of two belts 1 and 2 in a two-belt conveyor. The belts 1 and 2 are shown to abut one another across their entire width, but are flexible in the transverse direction of the belt plane at least in a center region between the belt edge portions 3, 4 and 5, 6, respectively, of the belts 1, 2 so that they can bulge outwardly away from one another to accommodate between themselves the material to be conveyed. The belts 1 and 2 are located on both sides of a center plane M of the belt conveyor and jointly moving in an endless path guided by rollers 7-14. Each edge portion 3, 5 at one longi¬ tudinal edge of the conveyor has, like the two edge portions 4 and 6 at the other longitudinal edge of the conveyor, a transverse force-absorbing element 15, 16 and 17, 18, respectively, which in cross-sec- tion has the shape of, for example, a truncated wedge. The elements 15-18 are joined together in some suit¬ able manner or made integral with the respective belt 1, 2 and are preferably reinforced such that they are relatively inflexible in the transverse di¬ rection about the shafts of the rollers 7-14 and in¬ flexible against torsion about the respective longi- tudinal center line.

The sealing at each longitudinal edge of the belt conveyor is achieved by making the respective belt edge portions 3, 5 and 4, 6 engage one another. More particularly the rollers 7, 8 and 11, 12 act as transverse force members in contact with the trans¬ verse force-absorbing elements 15, 16 and 17, 18, respectively, to apply to the belt edge portions 3, 5 and 4, 6, respectively, engaging one another at each longitudinal edge a compressive force as shown by the arrows P. Several such roller pairs 7, 8 and 11, 12, respectively, are distributed at suitable intervals along at least the sealed part of the belt conveyor.

The rollers 9, 10 and 13, 14 form second trans- verse force members which also are distributed along the sealed part of the belt conveyor, and engage with the transverse force-absorbing elements 15-18 to hold the longitudinal edges apart against the action of the material conveyed between the belts 1, 2. More particularly, the rollers 9, 10 and 13, 14 may be mounted in stationary roller mountings (not shown), the belts 1, 2 consisting, at least in the central part, of an elastic material and being bent out by the conveyed material. As a result of the bending-out of the belts 1, 2, the two longitudinal edges of the belt conveyor are drawn against each other, but the engagement between the rollers 9, 10 and 13, 14 and the sides of the transverse force-absorbing elements 15-18 holds the longitudinal edges apart, thus ensuring, in combination with the rollers 7, 8 and 11, 12, that the longitudinal edges of the belt conveyor are sealed. Alternatively, the rollers 9, 10 and 13, 14 may be adapted to stretch the belts 1, 2 in their trans¬ verse direction by applying to the transverse force- absorbing elements 15-18 divergent forces indicated by the arrows Q in Fig. 1. For example, the rollers 13, 14 may be mounted in a stationary roller mounting (not shown), while the rollers 9, 10 may be mounted in a roller mounting (not shown) which is spring-loaded in the outward direction from the associated belt edge. Other combinations of stationary and actively transverse force-applying mountings for the rollers 9, 10 and 13, 14 are, of course, conceivable.

In order to establish a reliable seal along the longitudinal edges of the belt conveyor, it is pre- ferred that the transverse force-absorbing elements 15-18 also absorb tensile forces in the longitudinal direction of the belts 1, 2, in which case the sealing along the longitudinal edges will be the result of a combination of longitudinally directed tensile forces in the elements 15-18, the torsional rigidity of these elements and the holding-together and holding-apart effect of the rollers 7-14.

According to the present invention, the two belt edge portions 3, 5 and 4, 6, respectively, at each longitudinal edge of the belt conveyor are bent out from the center plane M of the belt conveyor. As will appear from Fig. 2, the belt edge portions 3, 5 and 4, 6 may be bent out in the same direction relative to the center plane M. However, as will appear from Fig. 3, the belt edge portions 3, 5 may also be bent out in the opposite direction to the belt edge portions 4, 6.

Fig. 4 illustrates a guiding device in the form of a pair of rollers 19, 20 for the belt edge portions 3, 5 which are connected each with one transverse and tensile force-absorbing element 15, 16 extending along the entire belt length and urging said belt edge portions 3, 5 against one another by their contact with the rollers 19 and 20, respectively, while pro¬ viding a guiding effect such that the desired bending- out of the belt edge portions 3, 5 is obtained. The rollers 19, 20 are rotatably mounted each on a shaft 21, 22 mounted in an arm 23 which is carried by a frame (not shown). Each roller 19, 20 has a peripheral groove of the same cross-sectional shape as the tensile force-absorbing element 15 and 16, respectively. In Fig. 4, the groove cross-section has the form of a truncated wedge, but other cross-sectional shapes are also possible. The rollers 19, 20 replace both the rollers 7, 8 and the rollers 9, 10 in the schematic embodiment illustrated in Fig. 1. However, in the construction according to Fig. 4, also a roller con¬ figuration of the type shown in Fig. 1 may be used, or use may be made of a combination of these two con¬ figurations.

To further improve the contact between the belt edge portions 3, 5, at least the belt edge portion

3 in Fig. 4 has an insert 24 which extends along the entire length of this belt edge portion- and which, in the bent region, is outwardly spring-biased against the outer belt edge portion 5. Also the outer belt edge portion 5 may have a corresponding insert.

Fig. 5 illustrates an embodiment similar to the one shown in Fig. 4, but with the difference that the transverse and tensile force-absorbing elements 15", 16' make contact with one and the same roller 20' which consequently has two peripheral axially juxtaposed grooves. Alternatively, the roller 20' may suitably have the shape illustrated in Fig. 6 where the elements 15', 16' are in side-by-side con¬ tact. The roller 20' cooperates with a roller 19' which merely serves as a thrust roller. As in the embodiment according to Fig. 4, the rollers 19', 20' are rotatably mounted on shafts 21', 22' mounted in an arm 23' which is carried by a frame (not shown). The belt design shown in Fig. 5 where the tensile and transverse force-absorbing elements 15', 16' are facing in the same direction may, of course, be used in both examples of two-belt conveyors according to Figs. 2 and 3.

The arrangement according to the invention gives a highly reliable seal along the longitudinal edges of a two-belt conveyor, and the spacing between the roller pairs can be made relatively large. According to the invention, the force compressing the belt edge portions 3, 5 and 4, 6, respectively, may be further increased to make the seal even more re¬ liable, especially between the roller pairs, in that a subpressure is generated within the belt conveyor. To facilitate bending-out of the belt edge por¬ tions, each belt edge portion suitably is delimited from the adjoining intermediate portion by means of ^■a longitudinal bending indication in a position shown by dash-dot lines in Figs. 4 and 5. The bending indica- tion may be formed by means of inserts in the belt, as for example the insert 24 in Fig. 4. Alternatively, the bending indication may be in the form of a change in the belt thickness, as shown in Fig. 7.

The inner belt edge portion 3 as shown in Figs. 2-5 may preferably be preformed with a part which is located adjacent the belt edge at an angle in the di¬ rection of the outward bend relative to the center plane M of the belt conveyor, the more central part being located essentially in the center plane. The transition between the angled part and the more central part can constitute the bending indication, i.e. the angled part normally is bent out by an additional amount.

It is especially suitable that each belt 1, 2 consists of two separately manufactured belt edge portions 3, 4 and 5,6, respectively, and a separately manufactured intermediate part which are interconnected, for example vulcanised, to form the respective belt. For the intermediate part, a standard belt may be used. The load-contacting surface of each intermediate part must smoothly merge with the corresponding surface of the adjacent belt edge portions.

Claims

1. An arrangement in a two-belt conveyor, the two belts (1, 2) of which are sealed along a part of an endless path of motion at each longitudinal edge of the conveyor by means of two longitudinal belt edge portions (3, 5; 4, 6) contacting one another, each of said two belt edge portions (3, 5; 4, 6) being provided at each longitudinal edge with a transverse force-absorbing element (15-18) which extends along the entire belt length and projects from an adjacent part of the respective belt (1, 2), a plurality of first transverse force members (7, 8; 11, 12) being mounted along the sealed part in contact with said transverse force-absorbing elements (15-18) for applying a compressive force (P) to the two belt edge portions (3, 5; 4, 6) contacting one another at each longitudinal edge, and a plurality of second transverse"force members (9, 10; 13, 14) also arranged along the sealed part in engagement with said transverse force-absorbing elements (15-18) for keeping apart the two longitudinal edges of the conveyor against the action of the mate¬ rial conveyed between the belts (1, 2), c h a r a c ¬ t e r i s e d in that the two belt edge portions (3, 5; 4, 6) at each longitudinal edge are bent out from the center plane (M) of the belt conveyor.

2. An arrangement as claimed in claim 1, c h a ¬ r a c t e r i s e d in that the inner belt edge portion (3) within the bent region is outwardly spring-biased towards the outer belt edge portion (5).

3. An arrangement as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the inner belt edge portion (3) is preformed with a part which is located adjacent the belt edge at an angle in the direction of the outward bend relative to the center plane (M) of the belt conveyor, the more central part^' being located essentially in the center plane. 10

4. An arrangement as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that each belt edge portion (3, 4, 5, 6) is delimited from the adjoining intermediate portion by means of a longitudinal bending indication.

5. An arrangement as claimed in claim 4, c h a ¬ r a c t e r i s e d in that said bending indication is formed by means of inserts (24) or by a change in the belt thickness. 6. An arrangement as claimed in any one of claims 1-5, c h a r a c t e r i s e d in that the two belt edge portions (3, 5) at one longitudinal edge are bent out in opposite direction to the two belt edge portions (4,

6) at the other longitudinal edge.

7. An arrangement as claimed in any one of claims 1-6, c h a r a c t e r i s e d in that each belt (1, 2) consists of two separately manufactured belt edge 'portions (3, 4; 5, 6) and a separately manufactured intermediate part which are interconnected.

8. An arrangement as claimed in claim 1, c h a ¬ r a c t e r i s e d in that said first and second transverse force members (7 -14) are rollers.

9. An arrangement as claimed in claim 1, c h a ¬ r a c t e r i s e d in that said second transverse force members (9, 10; 13, 14) are adapted to stretch the belts (1, 2) in the transverse direction thereof by application of divergent forces (Q) to the trans¬ verse force-absorbing elements (15-18).

10. An arrangement as claimed in claim 1, c h a - r a c t e r i s e d in that the transverse force-ab¬ sorbing elements (15-18) also absorb tensile forces in the longitudinal direction of said belts (1, 2).