CA1162875A - Stretchable load-retaining conveyor belt - Google Patents
Stretchable load-retaining conveyor beltInfo
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- CA1162875A CA1162875A CA000384738A CA384738A CA1162875A CA 1162875 A CA1162875 A CA 1162875A CA 000384738 A CA000384738 A CA 000384738A CA 384738 A CA384738 A CA 384738A CA 1162875 A CA1162875 A CA 1162875A
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- belt
- layer
- cords
- edges
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Abstract
STRETCHABLE LOAD-RETAINING
CONVEYOR BELT
ABSTRACT OF THE DISCLOSURE
A conveyor salt of stretchable elastomeric material reinforced by layers of cords which permit an initial stretching of the belt at installation of at least 5 percent. Reinforcing cords are positioned in the belt elastomeric material to generate transverse forces during stretching of the belt which results in the interaction of the material of the belt with the cords. This interaction causes the edge portions of the belt to curl upwardly and form load-retaining walls at the edges. The belt may have a bottom stretchable portion which is reinforced to resist outside transverse forces resulting from the passage of the belt around a curve. A top stretchable portion of the belt has edge portions which bend upwardly to form the load-retaining.
walls. The edge portions of the belt may curl suffi-ciently to bring the edges together and they may be connected for enclosing the load on the belt surface.
CONVEYOR BELT
ABSTRACT OF THE DISCLOSURE
A conveyor salt of stretchable elastomeric material reinforced by layers of cords which permit an initial stretching of the belt at installation of at least 5 percent. Reinforcing cords are positioned in the belt elastomeric material to generate transverse forces during stretching of the belt which results in the interaction of the material of the belt with the cords. This interaction causes the edge portions of the belt to curl upwardly and form load-retaining walls at the edges. The belt may have a bottom stretchable portion which is reinforced to resist outside transverse forces resulting from the passage of the belt around a curve. A top stretchable portion of the belt has edge portions which bend upwardly to form the load-retaining.
walls. The edge portions of the belt may curl suffi-ciently to bring the edges together and they may be connected for enclosing the load on the belt surface.
Description
~7S ' The present invention relates to conveyor belts and especially to belts having load-retaining walls a-t the edges.
In most belt conveyors the belt is manufactured in a flat configuration but is troughed for retaining the conveyed material by rollers set at an angle and engaging the edge portions. Belts have also been molded in a U-shape such as the belt of my U.S. Patent No. 4,061,223.
In another case it was proposed to transversely prestretch the upper ply of a belt prior to curing so tha-t after curing it would contract and cause the belt edges to curve upwardly.
It has also been proposed to make the plies at the edges of the belt of materials having different coefficients of expansion so that during operation in a low temperature environment the edge portions will be curled upward and retain a fluid material. Other belts have been proposed having hinged edge portions which are supported by special brackets between a supporting power belt and the load-carrying container belt.
In some cases it is desirable to enclose the space over the load-carrying surface and belts have been made with retaining walls which have connecting edges. These belts have usually required elaborate mechanical equipment for connecting and disconnecting the edges.
According to the present invention, there is pro-vided a conveyor belt which is longitudinally stretchable at least 5 percent, said belt embodying belt narrowing means responsive to longitudinal s-tretching of said belt, and means resisting narrowing of said belt, said belt narrowing means being closer to -the load-carrying surface of said belt than said means resisting narrowing, whereby -tension on the belt genera-tes transverse forces bending the edges of the belt to form retaining walls for the load carried by the belt.
The present invention is directed to a conveyor belt which is stretchable a predetermined amount upon ins-'~
- - -tallation.
As abobe mentioned the belt edge portions curl up during the stretching and provide load-re-taining walls.
These walls may curl a greater or lesser amount depending on the belt construction and, where desired, may curl enough to connect the edges and enclose the material being conveyed. The belt edge portions curl up upon longitudi-nal stretching of the belt due to the interaction of belt narrowing means responsive to stretching of the belt and means resisting narrowing of the belt.
The belt narrowing means can be one or more layers of bias cords which pantograph upon elongation of the belt.
The means resisting narrowing can be a layer of transversely ex-tending cords or the elastomeric material of the belt.
It is usually desirable to have a belt cover a-t the load-carrying surface to protect the belt narrowing cords but the means resisting narrowing under the narrowing means must be sufficient to overcome the resistance of the elastomeric material of the cover and provide a sufficient net resistance in the desired direction to produce the curvature needed.
Since the edges of the belt in the present invention are under sufficien-t tension to hold the load without distortion, simple flat rollers may be used to support the load-carrying belt run.
Another advantage is derived from the minimum tension required to stretch the belt a predetermined amount upon installation. This minimum tension is more or less maintained throughout the belt length providing a built-in take-up action distributed along the entire belt conveyor rather than concentrating this action at a single point on the conveyor which may be a considerable distance from ~' ' where the take-up action is needed.
The novel construction thus provides a more uniform distribution of s-tresses and makes possible a conveyor which may have rollers spaced apart a greater distance than rollers for a conventional conveyor.
Preferred embodiments will now be described as example only, without limitative manner, with reference to the drawings, wherein: -Fig. 1 is a schematic side elevation of a stretchable belt embodying the invention mounted on a conveyor in the stretched condition, parts being broken away, and the unloading and loading conveyors being shown in chain-dotted lines.
Fig. 2 is a schematic plan view of the belt and conveyor shown in Fig. 1.
Fig. 3 is a fragmentary enlarged sectional view taken along the line 3-3 in Fig. 1.
Fig. 4 is an enlarged cross-sectional view of the belt of Figs. 1-3 in the unstretched condition showing the position of the reinforcing cords.
Fig. 5 is a cross-sectional view of the stret-chable belt of Fig. 4 showing the belt in the stretched condition.
Fig. 6 is a fragmentary cutaway plan view of the belt of Fig. 4 showing -the position of the reinforcing cords and plies.
Fig. 7 is a cross-sectional view of a modifi-cation of the belt construction embodying the invention.
Fig. B is a fragmentary cutaway view of the belt of Fig. 7.
Fig. 9 is a cross-sectional view of another modification of the invention.
Fig. 10 is a fragmentary cutaway view of the belt of Fig. 9.
Plg~ a cros~-~ectional view o~ a belt construction simllar to the belt of Figs. 9 and 10.
Fig. 12 ~8 ~ cros~-sec:tlonnl vlew of ~ modi~i-cation ~hown in the unstretched condition in whlch the belt i~ adapted to be trained around curve~.
Fig. 13 iB A frag~entary cutaw~y plan vlew o~
the belt of Flg. 12 in the unstretched conditio~.
Fig. 14 is a partially schematlc cro~-eectional view of the belt of Figs. 12 and 13 ~howing the belt in the stratched conditlon.
Fig. 15 i~ a cro~ ection~l view of a belt simllar to the belt of ~iy8. 12, 13 nnd 14.
Fig. 16 i8 A fragmentary cutaway plan view o~
th~ belt of Fig. 15.
Fig. 17 15 a schemAtic plan view of ~ conveyor includlng a further belt modification h~ving ~dge~
which are connected for enclo~ing the materlal conveyed.
~ lg. 18 i8 n fragmentary cro~ ection~l vlew of the helt of ~ig. 17 taken along the line 18-18 in Fig. 17.
Fig. 19 18 a cro~ ection~l view of the belt of Fig. 17 ~hown ln the unstretched conditionO
Fig. 20 i~ an enl~rged fragmen~ry sectlon~l vlew taken along the line 20-20 in Fig. 17, Pig. 21 i~ an enl~rged ~r~gme~tary soctlonal view taken along the line 21-21 in ~ig. 17, Fig. ~2 le a sectional vlo~ o~ ~nother b~lt similar to the belt o~ Flgn. 17-20.
~eferrlng to Fig~. 1 and 2, z conveyor 10 ~8 shown located ln a horlzont~l posltion for conv~ying bulk materlals such as coal ~rom a loadlng belt 11 at one end to an unlo~dlng b~lt 12 ~t the other end. The convayor 10 h~a a ~tr~tchable conveyor belt 13 extending over termlnal pulleys 8uch as tail pulley 14 and di.~charge pulley 15 located at the ends of the con-veyor. A ~uitable be~t drive 16 include6 an electric motor 17 or ~ther ~uitable power means connected to the dl.scharge pulley 15 by a flexlble chain or belt drive assen~ly 18.
With reference to F:Lgs. 1 and 3, a load-carrying upper run 19 of the conveyor ~elt 13 is supported by support rollers 22 mounted on roller frame~ 23 spaced longltudlnally ~long the conveyor 10.
A lower run 24 of the conveyor belt 13 is supported on split rollers 25 rotatably ~ounted on cent~r supports 26 which are ~tened to the roller frn~es 23.
As ~hown ln ~igs. 4 and 6, the conveyor belt 13 include~ an elongated elastomer~c ~ody o rubber or other rubberlike material with spac~d-apar~ ~dges 27 snd 28. A load-carrying belt surface 31 extends between the edge~ 27 and 28 and i~ located at the top side of the ~elt when in the load-carrying upper xun 19 of the conveyor 10.
The conveyor bslt 13 i8 stretchable at least 5 percent when sub~e~ted to lo~gitudlnal forces ln tenslon and ~ mounted in ten~ion on the conveyor 10.
In this embodim~nt the conveyor belt 1~ 1~ spliced a~
a length such that th~ b~lt ls elongated at lea~t 5 percent when 'n the mounted po~ition on the aonveyor 10.
Belt narrowing me~ns re~pon01ve to ~etching of the ~elt 13 ~uch a~ fir~t and second layers 32 ~nd 33 o~ bl~s cord r~in~orcing makerial g~nerate pxedetoro 30 mined transverse orces in a dlrection to reduce the width of the belt upon stretchlng durlng the lniti~l installation on the convoyor 10. Slnce the transverse force~ generat~ by the layera 32 and 33 are closest ~o.
~7S
the upper belt surface 31 and are resisted by the stiffness of the underlying material, the edges 27 and 28 and edge por-tions 29 and 30 of the belt 13 are caused to curl or bend upwardlyr as shown in Fig. 5, and thereby provide re-taining walls 34 and 35 at the edges for retaining material on the belt surface.
In other words, the first and second layers 32 and 33 are positioned closer to the belt surface 31 carrying the load than they are to the surface on the other side of the belt and this is believed to contribute further to bending of the edge portions 29 and 30 upwardly along the belt surFace 31. Also, as shown in Fig. 4, the first and second layers 32 and 33 separate the resilient material of the conveyor body into an upper portion 36 between said layers and the belt sur-face 31 and a lower portion 37 on the other side of the firstand second layers. Accordingly when the belt 13 is stretched the reduction in width of the belt surface 31 between the edges 27 and 28 is greater than the reduction in width of the belt at the lower portion 37 which further contributes to the curling or bending of the edges upwardly and away from the belt surface 31.
The belt 13, shown in detail in Figs. 4, 5 and 6, has a top cover 38 which may be of the same resilient material as the rest of the belt, or may be of a more wear-resistant material, because the belt surface 31 over this cover is exposed to abrasion from the material to be conveyed. The elastic material of the belt 13 is highly stretchable and has a hardness on the durometer scale from about 60 to 80. For installations in coal mines the material may be a flame-resistant elastomer. For above-ground operation, the material of the belt 13 may be any convent ~
-resistant rubber. The first and second layers 32 and 33 have reinforcing cords 39 and 40 laid on a bias of about 55 degrees and may be at angles in the range of from about 40 degrees to about 60 degrees relative to a transverse axis A-A of the belt shown in Fig. 6. The first layer 32 extends from edge 27 to edge 28 and the second layer 33 is coexten-sive with and positioned under the first layer, but with the cords 40 laid at an opposite bias angle to the cords 39 of the first layer.
10A third layer 43 of reinforcing cords is coexten-sive with and positioned under the second layer 33 and is formed of parallel cords 44 extending substantialIy trans-versely of the belt 13. A fourth layer 45 of reinforcing cords 46 is positioned under the third layer 43 with layer 15edges 47 and 48 spaced from the edges 27 and 28 or the belt 13. The cords 46 of the fourth layer 45 are laid on a bias at substantially the same angle as the cords 39 of the first layer 32. A fifth layer 49 of reinforcing cords 50 is coextensive with and positioned under the fourth layer 45 and has the cords laid on a bias at substantially the same angle as the cords 40 or the second layer-33.
The presence of the narrow band consisting of layers 45 and 49 of reinforcing material on the other side of the midplane balances the forces so that the reduction in width when the belt is stretched does not curl the center of the belt.
In the belt 13 of this embodiment, the cords 39, 40, 44, 46 and 50 of the first through fifth layers 32, 33, 43, 45 and 49 are of polyester and are spaced at about 22 ends per inch with each layer having a total thickness of about 0.05 inches. Separating or _~ ' .~ .
.~ . ' .
~s cushioning components 51 of elastomeric material are provided between the layers 32, 33, 43, 45 and 49 so that there can be relative angular movement of the cords 39 and 40, 40 and 44, 44 and 46, and 46 and 50. The relative movement of the cords contributes to the stretching of the belt 13 in the longitu-dinal direction and can be increased or decreased by changing the thickness of the cushioning components 51. In building the belt 13, the cords 39~ 40, 44, 46 and 50 may be covered by a skim coat of elastomeric rubber and after vulcanization the skim coats of overlapping layers form the cushioning com-ponents 51.
In the belt 13, shown in Figs. 4, 5 and 6, the cords 39, 40, 44, 46 and 50 have a thickness of about 0.03 inches and a skim coat of from about O.Ol to 0.02 inches is calendered or otherwise applied to each side of the cords resulting in each of the cushioning components 51 having a thickness of from about 0.02 to 0.04 inches. When the belt 13 is vulcanized the thickness of the cushioning components 51 will be reduced because of the removal of air and compact-ing of the elastomeric material. The top cover 38 has a - thickness of about 0.06 inches and a bottom layer or bottom cover 53 of the belt 13 has a thickness of about 0.06 inches at the center portion. The total thickness of the belt 13 in - the vulcanized condition is about 0.37 inches. The belt 13 -of this embodiment has a total wid-th of about 38 inches. The width of the fourth and fifth layers is about 20 inches and the width of each of the edge portions 29 and 30 of the belt is about 9 inches. The thickness of the bottom cover 53 is greater by 0.1 inches or 0.16 inches at the edge portions 29 and 30. This compares with the thickness of the top cover 38 of only 0.06 inches. It is therefore believed that the greater thickness of the bottom cover 53 adjacent the edges 27 and 28 of the belt 13 as co~ared with the thickness of the top cover 38 contributes to the curling or bending of the ~7S
edge portions 29 and 30 away fr~m the bottom cover and towards the top cover. In fact lt has been found that the greater the difference in thickness between the top cover 38 and the bottom cover 53 the greater is the tendency of the edge portions 29 and 30 to curl.
The belt 13 is built and vulcanized in a ~lat con-dition, as shown in Figs. 4 and 6, and then installed in a stretched condition as shown in Figs. 1, 2, 3 and 5. The initial stretching of the belt 13 of at least 5 percent and preferably in the range of from 5 to 15 percent causes the cords 39 and 40 of the first and second layers 32 and 33 and the cords 46 and 50 of the fourth and fifth layers 45 and 49 to pantograph and progressively resist further elongation as the belt is stretched. It has been found that with the cord angles of around 55 degrees relative to the transverse axis A-A the belt 13 may be stretched between 5 and 15 percent after which the resistance to stretching is substantial and sufficient for load-carrying operation of the conveyor 10.
It has also been found that the pantographing of the cords 39 and 40 in the first and second layers 32 and 33 generates a substantial transverse force which interacts with the resistance of the resilient material of the belt 13 and bends the edge portions 29 and 30 upwardly to function as retaining walls 34 and 35 as shown in Fig. 5. The cords 46 and 50 of the fourth and fifth layers 45 and 49 neutrali~e the action of the cords 39 and 40 of the first and second layers 32 and 33 at the center portion of the belt 13, thus maintaining a relatively flat surface 31 between the curled side edge portions 29 and 30. The transverse cords 44 of the third layer 43 further resist a reduction in width or narrowing of the belt 13 and accordingly con-tribute to the curling or bending of the edge portions 29 and 30. Nevertheless, when the belt 13 passes over the tail pulley 14 and discharge pulley 15 it will flatten out as shown in Figs. 1 and 2. -~5 In the return lower run 24 the belt 13 is in the stretched condition and retaining walls 34 and:35 extend downwardly at each side of the split rollers 25. As shown in Fig. 3, if the belt 13 in the lower run Z4 travels to either side, it wi-ll-be prevented from running of:E the split rollers 25 by engagement of the retaining walls 34 and 35 with the ends of the split rollers.
As described hereinabove, when the belt 13 is subjected to a sufficient tension, the walls 34 and 35 will be retained in the operating condition for containiny the bulk material so tha-t the rollers 22 may be cylindrical. The substantial tension maintained throughout the leng-th of the - belt 13 also makes possible a greater spacing between the support rollers 22 than is possible with a conventional con-veyor belt.
Referring to Figs. 7 and 8, a modified constructionof a conveyor belt 54 is shown having an elongated elastomeric body of resilient material with spaced edges 55 and 56. A
first layer 57 has reinforcing cords 58 laids on a bias of about 45 degrees to transverse axis B-s of the belt and ex'~ends between the edges 55 and 56 of the belt 54. The belt 54 has a load-carrying belt surface 59 on a top cover 62 under which the first layer 57 is located. A second layer 63 of reinforcing cords 64 is positioned under said first layer,57 - with the cords laid at an opposi-te bias angle of 45 degrees to the angle of the cords 58 of -the first layer. The second layer 63 has edges 65 and 66 whi.ch are spaced from the edges 55 and 56 of the belt 54 providing a center portion between the edges 65 and 66. Edge portions 67 and 68 are also pro-vided between the edges 55 and 65 and the edges 56 and 66.
A bottom cover 69 is positioned under the second layer 63 and has a thickness of about 0.07 inches at the center portion. The top cover 62 also has a thickness of about 0.07 inches and the first layer 57 and second layer 63 each have a thickness of about 0.05-inches. A cushioning component 70 is located between the cords 58 and 64 of the first and second layers 57 and 63 and may have a -thickness of about 0.01 to 0.02 inches prior to vulcanization of the be-lt 54. As shown in Figs. 7 and 8, the thickness of the bottom cover 69 at the edge portions 67 and 68 is greater than the thickness at the center portion which further con-tributes to the curling or bending upwards of the edge por-tions.
The cords 58 and 64 of the first and second layers 57 and 63 are of a suitable textile material such as polyester and may be spaced at about 22 ends per inch. The width of the belt is about 34 inches with the center portion having a width of 10 inches and the edge portions 67 and 68 each having a width of about 12 inches in the unstretched condition. The belt 54 is stretchable at least 5 percent and when stretched decreases in width a proportional amount. Also the edge por-tions 67 and 68 bend upwardly to provide retaining walls at the sides of the belt surface 59 in the stretched condition in a similar manner to that described hereinabove for the embodiment of Figs. 4, 5 and 6. The cords 64 of the second layer 63 neutralize the curling action of the cords 58 of the first layer 57 and provide a relatively flat surface 59 between the curled side edges 55 and 56.
Another modification is shown in Fiys. 9 and 10 in which a belt 71 has an elongated elastomeric body with edges 72 and 73 and a belt surface 74 extending between the edges.
The belt 71 has a center portion 75 with margins 76 and 77 spaced from the edges 72 and 73 providing edge portions 78 and 79. The belt surface 74 is on a top cover 82 which has a thickness of about 0.07 inches. The top cover 82 may be of a resilient material having good wear characteristics as indi-cated above. Under the top cover 82 is a first layer 83 of reinforcing cords 84 and 85 in the edge portions 78 and 79, ~L~6~75 respectively. The irst layer 83 extends from the eclges 72 and 73 of the belt 71 to the margins 76 and 77 of the central portion 75 in the edge portions 78 and 79. The cords 84 in the edge portion 78 are laid on a bias to the transverse axis C-C at an angle of 45 degrees in one direc-tion. The cords 85 of the edge portion 79 are laid at an angle of 45 degrees to the transverse axis C-C and at an opposite bias angle -to the cords 84 of the other edge portion 78. Under the first layer 83 is a second layer 86 of.re-inforcing cords 87 and 88 in edge portions 78 and 79 laid at an angle of 45 degrees to the transverse axis C-C but at an - opposite bias angle direction to the cords 84 and 85 of the first layer.
Under the second layer 86 is a third layer 89 of square woven stretch fabric 90.
-~L~6Za~S
The third layer 89 extends from one edge 72 of the belt 71to the other edge 73. The stretch fabric 90 of the third layer 89 has the property of stretching a predetermined distance when subject to tension during the initial stretch-ing of the belt 71 and then its resistance to further elon-gation increases rapidly to resist any appreciable stretching of the belt in operation.
In this modification, the top cover 82 has thick-ness of about 0.07 inches. The first layer 83 is of poly-ester cords spaced at about 22 ends per inch with the firstlayer having a thickness of about 0.05 inches. The second layer 86 also has a thickness of about 0.05 inches and polyester cords spaced at about 22 ends per inch. A bottom cover 93 under the third layer 89 has a thickness of about 0.07 inches. Cushioning components 92 are located between the cords 89 and 85 of the first and second layers 83 and 86 and between the cords 87 of the second layer 86 and the stretch fabric 90 of the third layer 89. The cushioning components 92 may have a thickness of about 0.01 to 0.02 inches prior to vulcanization.
In operation the belt 71 is built and vulcanized in the flat condition as shown in Figs. 9 and 10 with the stretch fabric 90 of the third layer 89 in the unstretched condition. Upon installation of the belt 71 on a conveyor, the belt is initially stretched a predetermined amount of at least 5 percent, at which point further stretching of the belt is stronlgy resisted. During the stretching process, the cords 84, - - --~ ~ !
85, 87 and 88 of the first and second layers 83 and 36 pantograph and bend the edge portions 78 and 79 upwardly at the sides of the belt surface 74 providing retaining walls such as those shown in Figs~ 3 and 5. With the stretch fabric 90 of the third layer 89 -the longitudinal force neces-sary for initial stretching of the belt 71 is less than it would be if the stretching of the belt was limited by layers of reinforcing cord laid on a bias such as that shown in the modifications of Figs. 4 through 8. Also -transverse cords oE
the stretch fabric 90 resist reduc-tion in width of the belt 71 and contribute to -the bending of the edge por-tions 78 and 79.
Referring to Fig. 11, a belt 71' is shown which is identical to the belt of Figs. 9 and 10 except that in the second layer 86' a center portion 94 has been added to fill the space between the margins 76' and 77'. The center portion 94 of the second layer 86' is of square woven stretch fabric 95 having the property of being stretchable upon initial stretching of the belt 71' during installation on the con-veyor and then having a high resistance to further stretchingof the belt in operation. The stretch fabric 95 of the center portion 94 of the second layer 86' may have the same charac-teristics as the stretch fabric 90 of the third layer 89 of the belt 71 sho~n in Figs. 9 and 10. The cushioning component 92' between the cords of the second layer 86' and the stretch fabric of the third layer 89' also extends between the stretch fabric of the second and third layers. In operation, the belt of Fig. 11 is stretchable and will provide upstanding re-tain-ing walls in a similar manner to the belt of Figs. 9 and 10:
however, the belt of Fig. 11 may have greater strength in the longitudinal direction in the s-tretched condition.
- A belt 96 adaptable for movement around curves is shown in Figs. 12, 13 ancl 14. 'l'l~e belt 96 has an elonga-ted elastomeric body with a top portion 97 and a bottom portion 98 connected at a center portion 99. As shown in FicJs. 12 and 13, the top portion 97 has a top cover 102 extending between edges 103 and 104 which may be of a resilien-t material having good wear characteristics. Under the top cover 102 is a first layer 105 of reinforcing cords 106 in eage portions 108 and 109 extending inward from edges 103 and 104 to the center portion 99. The cords 106 in the edge por-tions 108 and 109 are laid at a bias angle of about 45 degrees to the transverse axis D-D.
Under the first layer 105 is a second layer 112 of reinforcing cords 113 coextensive with the cords 106 of the first layer 105. The reinforcing cords 113 are laid at an angle of about 45 degrees to the transverse axis D-D and at an opposite bias angle to the cords 106 of the first layer 105.
Under the second layer 112 is a third layer 115 of transversely extending cords 116 between the edges 103 and 104 of the belt 96. Under the third layer 115 is a middle cover 118 which is connected at the center portion 99 to a middle cover 119 of the bottom portion 98. As shown in Figs.
12, 13 and 14, the bottom portion 98 in the unstretched con-dition preferably has a width less than the width of the top portion 97.
Under the middle cover 119 is a fourth layer 122 of reinforcing cords 123 extendiny -transversely between the edges 103 and 104 of the bottom portion 98 of the bel-t 96.
Preferably the reinforcing cords 123 are of a high modulus material such as steel.
Under the fourth layer 122 is a fifth layer 124 of reinforcing cords 125 positionecl at a bias angle substantially the same as the bias angle of the cords 106 of the first layer 105 and extending from edge-to-edge of the center portion 99.
Under the fifth layer 124 and coextensive therewith is a sixth layer 126 of reinforcing cords 127 laid on a ~ias at an ~1~2~75 angle similar to the angle of cords 113 of the second layer 112.
Under the sixth layer 126 is.a seventh layer ].28 of reinforcing cords 129 extending transversely between the edges 103-and 104. The cords 129 are preferably of high modulus material such as steel. Under the seventh layer 128 is a bottom cover 130 which e~tends from edge 103 to edge 104 of the bottom portion ~8. The transverse cords 129 of -the seventh layer 128 and cords 123 of the fourth layer 122 are spaced longitudinally of the belt 96 sufficiently to permit longitudinal stretching of the belt 96 by an initial amount of at least 5 percent. During this stretching the cords 106 and 113 of the first and second layers 105 and 112 interact with the transverse cords 116 of the third layer 115 and with the elastomeric material of the belt 96 causing the upper surface of the edge portions 108 and 109 to contract laterally and bend upwardly forming retaining walls 131 and 132 for con-taining material being conveyed on a load-carrying belt sur-face 133. Cushioning com~onents 139 are located between the cords of the first and second layers 105 and 112, the second and third layers 112 and 115, the fourth and fifth layers 122 and 124, the fifth and sixth layers 124 and 126, and the sixth and seventh layers 126 and 128.
. The belt 96 is-fabricated and molded in the flat condition shown in Figs. 12 and 13 with the edge portions 108 and 109 of the top portion 97 and bottom portion 98 separated by a sheet or plate of material to form slots 134 and 135 - extending to the center portion 99. In operation the belt 96 is stretchable an initial amount of from 5 to 15 percent due to the pantographing of the reinforcing cords 106 of the first layer 105, reinforcing cords 113 of the second layer 112, cords 125 of -the fifth layer 124, and cords 121 of the sixth layer 126. The in-teraction of the cords 106 of the f~rst layer 105 and the cor~s 113 of the second layer 112 7~i - with the elastomeric material of the belt 96 and the trans-verse cords 116 of the third layer 115 during the stretching of the belt causes the edge portlons 108 and 109 to bend upwardly and form -the walls 131 and 132.
In this embodiment the top cover 102 has a thick-ness of about 0.07 inches a-t the edge portions 108 and 109 and about 0.13 inches at the center portion 99. The re-inforcing cords 106 of the first layer 105 and cords 113 of the second layer 112 may be of polyester and be spaced at about 22 ends per inch. The thickness of the first and second layers 105 and 112 may be about 0.05 inches each. The third layer 115 may also have reinforcing polyester cords 116 spaced at about 22 ends per inch and have a thickness of about 0.05 inches. The middle cover 118 for the top portion 97 may have a thickness of about 0.07 inches.
The middle cover 119 of the bottom portion 98 may also have a thickness of about 0.07 inches. The transverse reinforcing cords 123 and 129 of the Eourth and seventh layers 122 and 128 may be steel strands spaced at eight ends per inch and having a thickness of about 0.1 inches. The fifth and sixth layers 124 and 126 may have reinforcing polyester cords 125 and 127 spaced at about 22 ends per inch with a thickness of about 0.05 inches for each layer. The bottom cover 130 may -have a thickness of 0.07 inches. The cushioning components 139 may have a thickness depending on the thickness of the skim coat on the cords. The cords of polyester have a skim coat of a thickness oE from about 0.01 to 0.02 inches and the - cords of steel have a skim coat of from about 0.01 to 0.03 inches. Therefore the to-tal thickness of the cushioning com-ponents 139 may be from about 0.02 to 0.05 inches.
In operation when the bel-t 96 is clirected around a curve the bottom portion 98 resists transverse deflection of the belt and supports the top portion 97 which has the walls 131 and 132 for re-taining the material on the belt surface S
133. Due to the stretching of the,walls 131 and 132 they will be maintained in position even though the elongation of the belt 96 varies across -the wicl-th of the bel~. Normally pulleys (not shown) are positioned around the edges 103 and 104 of the bottom portion 98 and also under the bottom cover 130 to maintain the configuration of the belt 96 around curves.
- A belt 136 is shown in Figs. 15 and 16 which is similar to the belt 96 shown in Figs. 12, 13 and 14. However~
instead of the fifth and sixth layers 124 and 126 of re-inforcing cords 123 and 125 being positioned at a bias angle to the transverse axis D-D, a separating layer 137 oE square woven stretch fabric 138 extending between the edges of the center portion 99' is positioned between the fourth and seventh layers 122' and 128'. The stretch fabric 138 of the separating layer 137 has the property of stretching a pre-determined distance upon initial stretching during installa-tion of the belt 136 from about 5 to 15 percent and then has a high resistance to further stretching of the belt in opera-tion. In other respects the construction of belt 136 of Figs.
15 ancl 16 is the same as the construction of the belt 96 except there is one less cushioning component 139'. In operation the transverse cords of the stretch fabric 138 and the elastomeric material of the belt 136 interact with the reinforcing cords 106' of the first layer 105' and the cords 113' of the second layer 112' to bend the edge portions 108' and 109' of the top portion 97' upwardly into the shape shown in Fig. 14.
Referring to Figs. 17, 18, 19, 20 and 21 a further modification is shown in which a belt 142 having a construc-tion shown in greater detail in Fig. 19 has edge portiQns 143 and 144 and a center portion 145. The edge portions 143 and 144 are located between the center portion 145 and edges 146 and 147 of the belt 142. The eclge portions 143 and 144 may be divided into outer margins 148 and 149 ad~acent the edges .... . .. . .. . ....... . ... .. . . .
146 and 147 and inner margins 152 and 153 adjacent the center portion 145. The bel-t 142 may be of an elastomeric material and have a construction similar to the construction described hereinabove for the belt 13 shown in Figs. 4 and 5 except that the belt 142 shown in Fig. 19 has edge portions 143 and 144 of greater wid-th than the edge portions of the belt 13 by the width of the outer margins 148 and 199. Also the third layer 43' extends beyond the ends of the first and - second layers 32' and 33' so that when the belt 142 is in the stretched condition as shown in Fig. 18 the edye portions 143 and 144 will overlap to enclose the space above the load-carrying belt surface 31l. With the construction of the belt 142 the thickness of the belt at the outer margins 148 and 149 is reduced which also reduces the weight at the edges 146 and 147.
As shown in Figs~ 19 and 20 connecting means such as channels 154 and 155 are mounted on the bottom cover 53' at the outer margin 149 and ribs 156 and 157 are mounted on the surface 31' of the top cover 38' at the other outer margin 148 for matching engagement upon pressing of the margin 148 against the margin 149 by suitable means such as rollers 158 and 159. As shown in Fig. 17 the rollers 158 and 159 may be mounted on a frame 162 at one end of a con-veyor 163 close to the tail pulley 164. After the load is applied to the belt surface 31' and the belt 142 takes the configuration shown in Fig. 18 the ribs 156 and 157 may be pushed into engagement with the channels 154 and 155 provid-ing a sealed chamber within the belt for conveying material.
At the discharge end of the conveyor 163, discharge pulley 165 tends to spread the walls 34' and 35' and as shown in Fig. 21 separating rollers 166 and 167 may be used to assist in this ac-tion and pull the ribs 156 and 157 out oE the channels 154 and 155 so that the material conveyed on the surface 31 may be discharged and the return run 168 carried 75~
back to the tail pulley 164 by suitable rollers 169 as shown in Fig. 18. The upper run 170 may be supported by support rollers 172. As shown in Fig. 18 a roller frame 173 mounted on a supporting surface such as the ground or hung from the roof supports the rollers 169 and 172.
In operation the belt 142 is mounted on the con-veyor 163 under tension in a similar manner to that described hereinabove for the other modifications. As the belt 142 is driven from the tail pulley 164 to the discharge pulley 165 the rollers 158 and 159 will urge the ribs 156 and 157 into engagement with the channels 155 and 154. Then at the dis-charge end the discharge pulley 165 spreading -the walls 34' and 35' and supplemented by the separating rollers 166 and 167 will pull the ribs 156 and 157 out of the channels 154 and 155 and permit the discharge of the material at the dis-charge pulley 165. The elastomeric material of the belt 142 and the reinforcing cords may be the same as that described hereinabove for the belt 13 of Figs. 4, 5 and 6. The channels 154 and 155 and ribs 156 ana 157 may be of a resilient ma-terial such as nylon which is adhered to the belt 142 by a suitable adhesive.
Referring to Fig. 22 a belt 174 has a construction similar to the construction of the belt 71' shown in Fig. 11 except that the first layer 83 " and second layer 86 " extend over only inner margins 175 and 176 adjacent the central portion 75 " . Outer margins 177 and 178 extend beyond the ends of the first and second layers 83 " and 86 " and are adjacent the edges- 72 " and 73 " of the belt 174. Also con-necting means such as channels 179 and 182 are mounted on the bottom cover 93 " at the outer margin 178 and ribs 183 and 184 are mounted on the surface 74 " of the top cover 82 " at the outer margin 177 for matching engagement upon pressing of the margin 177 against the margin 178 by suitable means such as the rollers 158 and 159 shown in Fig. 20.
In operation the belt 174 is mounted on a conveyor similar to the conveyor 163 shown in Fig. 17 and operated under tension in the same manner as that described for the belt 142 shown in Figs. 17, 18, 19 and 20.
In Figs. 19 and 21 the belts 142 and 174 have outer margins 148, 149, 177 and 178 which are shown substantially equal in width to the corresponding inner margins 152, 153, 176 and 175. I-t is evident that the outer margins may have a width substantially greater than the width of the inner margins and be in relation to the wid-th of -the center por-tions 145 and 75" so that the edges will overlap to enclose the load carried by the belts.
While certain representative embodiments and details have been shown for the purpose of illustrating the inven-tion it will be apparent to those skilled in the art that various changes and modifications may be made therein without depart-ing from the invention.
In most belt conveyors the belt is manufactured in a flat configuration but is troughed for retaining the conveyed material by rollers set at an angle and engaging the edge portions. Belts have also been molded in a U-shape such as the belt of my U.S. Patent No. 4,061,223.
In another case it was proposed to transversely prestretch the upper ply of a belt prior to curing so tha-t after curing it would contract and cause the belt edges to curve upwardly.
It has also been proposed to make the plies at the edges of the belt of materials having different coefficients of expansion so that during operation in a low temperature environment the edge portions will be curled upward and retain a fluid material. Other belts have been proposed having hinged edge portions which are supported by special brackets between a supporting power belt and the load-carrying container belt.
In some cases it is desirable to enclose the space over the load-carrying surface and belts have been made with retaining walls which have connecting edges. These belts have usually required elaborate mechanical equipment for connecting and disconnecting the edges.
According to the present invention, there is pro-vided a conveyor belt which is longitudinally stretchable at least 5 percent, said belt embodying belt narrowing means responsive to longitudinal s-tretching of said belt, and means resisting narrowing of said belt, said belt narrowing means being closer to -the load-carrying surface of said belt than said means resisting narrowing, whereby -tension on the belt genera-tes transverse forces bending the edges of the belt to form retaining walls for the load carried by the belt.
The present invention is directed to a conveyor belt which is stretchable a predetermined amount upon ins-'~
- - -tallation.
As abobe mentioned the belt edge portions curl up during the stretching and provide load-re-taining walls.
These walls may curl a greater or lesser amount depending on the belt construction and, where desired, may curl enough to connect the edges and enclose the material being conveyed. The belt edge portions curl up upon longitudi-nal stretching of the belt due to the interaction of belt narrowing means responsive to stretching of the belt and means resisting narrowing of the belt.
The belt narrowing means can be one or more layers of bias cords which pantograph upon elongation of the belt.
The means resisting narrowing can be a layer of transversely ex-tending cords or the elastomeric material of the belt.
It is usually desirable to have a belt cover a-t the load-carrying surface to protect the belt narrowing cords but the means resisting narrowing under the narrowing means must be sufficient to overcome the resistance of the elastomeric material of the cover and provide a sufficient net resistance in the desired direction to produce the curvature needed.
Since the edges of the belt in the present invention are under sufficien-t tension to hold the load without distortion, simple flat rollers may be used to support the load-carrying belt run.
Another advantage is derived from the minimum tension required to stretch the belt a predetermined amount upon installation. This minimum tension is more or less maintained throughout the belt length providing a built-in take-up action distributed along the entire belt conveyor rather than concentrating this action at a single point on the conveyor which may be a considerable distance from ~' ' where the take-up action is needed.
The novel construction thus provides a more uniform distribution of s-tresses and makes possible a conveyor which may have rollers spaced apart a greater distance than rollers for a conventional conveyor.
Preferred embodiments will now be described as example only, without limitative manner, with reference to the drawings, wherein: -Fig. 1 is a schematic side elevation of a stretchable belt embodying the invention mounted on a conveyor in the stretched condition, parts being broken away, and the unloading and loading conveyors being shown in chain-dotted lines.
Fig. 2 is a schematic plan view of the belt and conveyor shown in Fig. 1.
Fig. 3 is a fragmentary enlarged sectional view taken along the line 3-3 in Fig. 1.
Fig. 4 is an enlarged cross-sectional view of the belt of Figs. 1-3 in the unstretched condition showing the position of the reinforcing cords.
Fig. 5 is a cross-sectional view of the stret-chable belt of Fig. 4 showing the belt in the stretched condition.
Fig. 6 is a fragmentary cutaway plan view of the belt of Fig. 4 showing -the position of the reinforcing cords and plies.
Fig. 7 is a cross-sectional view of a modifi-cation of the belt construction embodying the invention.
Fig. B is a fragmentary cutaway view of the belt of Fig. 7.
Fig. 9 is a cross-sectional view of another modification of the invention.
Fig. 10 is a fragmentary cutaway view of the belt of Fig. 9.
Plg~ a cros~-~ectional view o~ a belt construction simllar to the belt of Figs. 9 and 10.
Fig. 12 ~8 ~ cros~-sec:tlonnl vlew of ~ modi~i-cation ~hown in the unstretched condition in whlch the belt i~ adapted to be trained around curve~.
Fig. 13 iB A frag~entary cutaw~y plan vlew o~
the belt of Flg. 12 in the unstretched conditio~.
Fig. 14 is a partially schematlc cro~-eectional view of the belt of Figs. 12 and 13 ~howing the belt in the stratched conditlon.
Fig. 15 i~ a cro~ ection~l view of a belt simllar to the belt of ~iy8. 12, 13 nnd 14.
Fig. 16 i8 A fragmentary cutaway plan view o~
th~ belt of Fig. 15.
Fig. 17 15 a schemAtic plan view of ~ conveyor includlng a further belt modification h~ving ~dge~
which are connected for enclo~ing the materlal conveyed.
~ lg. 18 i8 n fragmentary cro~ ection~l vlew of the helt of ~ig. 17 taken along the line 18-18 in Fig. 17.
Fig. 19 18 a cro~ ection~l view of the belt of Fig. 17 ~hown ln the unstretched conditionO
Fig. 20 i~ an enl~rged fragmen~ry sectlon~l vlew taken along the line 20-20 in Fig. 17, Pig. 21 i~ an enl~rged ~r~gme~tary soctlonal view taken along the line 21-21 in ~ig. 17, Fig. ~2 le a sectional vlo~ o~ ~nother b~lt similar to the belt o~ Flgn. 17-20.
~eferrlng to Fig~. 1 and 2, z conveyor 10 ~8 shown located ln a horlzont~l posltion for conv~ying bulk materlals such as coal ~rom a loadlng belt 11 at one end to an unlo~dlng b~lt 12 ~t the other end. The convayor 10 h~a a ~tr~tchable conveyor belt 13 extending over termlnal pulleys 8uch as tail pulley 14 and di.~charge pulley 15 located at the ends of the con-veyor. A ~uitable be~t drive 16 include6 an electric motor 17 or ~ther ~uitable power means connected to the dl.scharge pulley 15 by a flexlble chain or belt drive assen~ly 18.
With reference to F:Lgs. 1 and 3, a load-carrying upper run 19 of the conveyor ~elt 13 is supported by support rollers 22 mounted on roller frame~ 23 spaced longltudlnally ~long the conveyor 10.
A lower run 24 of the conveyor belt 13 is supported on split rollers 25 rotatably ~ounted on cent~r supports 26 which are ~tened to the roller frn~es 23.
As ~hown ln ~igs. 4 and 6, the conveyor belt 13 include~ an elongated elastomer~c ~ody o rubber or other rubberlike material with spac~d-apar~ ~dges 27 snd 28. A load-carrying belt surface 31 extends between the edge~ 27 and 28 and i~ located at the top side of the ~elt when in the load-carrying upper xun 19 of the conveyor 10.
The conveyor bslt 13 i8 stretchable at least 5 percent when sub~e~ted to lo~gitudlnal forces ln tenslon and ~ mounted in ten~ion on the conveyor 10.
In this embodim~nt the conveyor belt 1~ 1~ spliced a~
a length such that th~ b~lt ls elongated at lea~t 5 percent when 'n the mounted po~ition on the aonveyor 10.
Belt narrowing me~ns re~pon01ve to ~etching of the ~elt 13 ~uch a~ fir~t and second layers 32 ~nd 33 o~ bl~s cord r~in~orcing makerial g~nerate pxedetoro 30 mined transverse orces in a dlrection to reduce the width of the belt upon stretchlng durlng the lniti~l installation on the convoyor 10. Slnce the transverse force~ generat~ by the layera 32 and 33 are closest ~o.
~7S
the upper belt surface 31 and are resisted by the stiffness of the underlying material, the edges 27 and 28 and edge por-tions 29 and 30 of the belt 13 are caused to curl or bend upwardlyr as shown in Fig. 5, and thereby provide re-taining walls 34 and 35 at the edges for retaining material on the belt surface.
In other words, the first and second layers 32 and 33 are positioned closer to the belt surface 31 carrying the load than they are to the surface on the other side of the belt and this is believed to contribute further to bending of the edge portions 29 and 30 upwardly along the belt surFace 31. Also, as shown in Fig. 4, the first and second layers 32 and 33 separate the resilient material of the conveyor body into an upper portion 36 between said layers and the belt sur-face 31 and a lower portion 37 on the other side of the firstand second layers. Accordingly when the belt 13 is stretched the reduction in width of the belt surface 31 between the edges 27 and 28 is greater than the reduction in width of the belt at the lower portion 37 which further contributes to the curling or bending of the edges upwardly and away from the belt surface 31.
The belt 13, shown in detail in Figs. 4, 5 and 6, has a top cover 38 which may be of the same resilient material as the rest of the belt, or may be of a more wear-resistant material, because the belt surface 31 over this cover is exposed to abrasion from the material to be conveyed. The elastic material of the belt 13 is highly stretchable and has a hardness on the durometer scale from about 60 to 80. For installations in coal mines the material may be a flame-resistant elastomer. For above-ground operation, the material of the belt 13 may be any convent ~
-resistant rubber. The first and second layers 32 and 33 have reinforcing cords 39 and 40 laid on a bias of about 55 degrees and may be at angles in the range of from about 40 degrees to about 60 degrees relative to a transverse axis A-A of the belt shown in Fig. 6. The first layer 32 extends from edge 27 to edge 28 and the second layer 33 is coexten-sive with and positioned under the first layer, but with the cords 40 laid at an opposite bias angle to the cords 39 of the first layer.
10A third layer 43 of reinforcing cords is coexten-sive with and positioned under the second layer 33 and is formed of parallel cords 44 extending substantialIy trans-versely of the belt 13. A fourth layer 45 of reinforcing cords 46 is positioned under the third layer 43 with layer 15edges 47 and 48 spaced from the edges 27 and 28 or the belt 13. The cords 46 of the fourth layer 45 are laid on a bias at substantially the same angle as the cords 39 of the first layer 32. A fifth layer 49 of reinforcing cords 50 is coextensive with and positioned under the fourth layer 45 and has the cords laid on a bias at substantially the same angle as the cords 40 or the second layer-33.
The presence of the narrow band consisting of layers 45 and 49 of reinforcing material on the other side of the midplane balances the forces so that the reduction in width when the belt is stretched does not curl the center of the belt.
In the belt 13 of this embodiment, the cords 39, 40, 44, 46 and 50 of the first through fifth layers 32, 33, 43, 45 and 49 are of polyester and are spaced at about 22 ends per inch with each layer having a total thickness of about 0.05 inches. Separating or _~ ' .~ .
.~ . ' .
~s cushioning components 51 of elastomeric material are provided between the layers 32, 33, 43, 45 and 49 so that there can be relative angular movement of the cords 39 and 40, 40 and 44, 44 and 46, and 46 and 50. The relative movement of the cords contributes to the stretching of the belt 13 in the longitu-dinal direction and can be increased or decreased by changing the thickness of the cushioning components 51. In building the belt 13, the cords 39~ 40, 44, 46 and 50 may be covered by a skim coat of elastomeric rubber and after vulcanization the skim coats of overlapping layers form the cushioning com-ponents 51.
In the belt 13, shown in Figs. 4, 5 and 6, the cords 39, 40, 44, 46 and 50 have a thickness of about 0.03 inches and a skim coat of from about O.Ol to 0.02 inches is calendered or otherwise applied to each side of the cords resulting in each of the cushioning components 51 having a thickness of from about 0.02 to 0.04 inches. When the belt 13 is vulcanized the thickness of the cushioning components 51 will be reduced because of the removal of air and compact-ing of the elastomeric material. The top cover 38 has a - thickness of about 0.06 inches and a bottom layer or bottom cover 53 of the belt 13 has a thickness of about 0.06 inches at the center portion. The total thickness of the belt 13 in - the vulcanized condition is about 0.37 inches. The belt 13 -of this embodiment has a total wid-th of about 38 inches. The width of the fourth and fifth layers is about 20 inches and the width of each of the edge portions 29 and 30 of the belt is about 9 inches. The thickness of the bottom cover 53 is greater by 0.1 inches or 0.16 inches at the edge portions 29 and 30. This compares with the thickness of the top cover 38 of only 0.06 inches. It is therefore believed that the greater thickness of the bottom cover 53 adjacent the edges 27 and 28 of the belt 13 as co~ared with the thickness of the top cover 38 contributes to the curling or bending of the ~7S
edge portions 29 and 30 away fr~m the bottom cover and towards the top cover. In fact lt has been found that the greater the difference in thickness between the top cover 38 and the bottom cover 53 the greater is the tendency of the edge portions 29 and 30 to curl.
The belt 13 is built and vulcanized in a ~lat con-dition, as shown in Figs. 4 and 6, and then installed in a stretched condition as shown in Figs. 1, 2, 3 and 5. The initial stretching of the belt 13 of at least 5 percent and preferably in the range of from 5 to 15 percent causes the cords 39 and 40 of the first and second layers 32 and 33 and the cords 46 and 50 of the fourth and fifth layers 45 and 49 to pantograph and progressively resist further elongation as the belt is stretched. It has been found that with the cord angles of around 55 degrees relative to the transverse axis A-A the belt 13 may be stretched between 5 and 15 percent after which the resistance to stretching is substantial and sufficient for load-carrying operation of the conveyor 10.
It has also been found that the pantographing of the cords 39 and 40 in the first and second layers 32 and 33 generates a substantial transverse force which interacts with the resistance of the resilient material of the belt 13 and bends the edge portions 29 and 30 upwardly to function as retaining walls 34 and 35 as shown in Fig. 5. The cords 46 and 50 of the fourth and fifth layers 45 and 49 neutrali~e the action of the cords 39 and 40 of the first and second layers 32 and 33 at the center portion of the belt 13, thus maintaining a relatively flat surface 31 between the curled side edge portions 29 and 30. The transverse cords 44 of the third layer 43 further resist a reduction in width or narrowing of the belt 13 and accordingly con-tribute to the curling or bending of the edge portions 29 and 30. Nevertheless, when the belt 13 passes over the tail pulley 14 and discharge pulley 15 it will flatten out as shown in Figs. 1 and 2. -~5 In the return lower run 24 the belt 13 is in the stretched condition and retaining walls 34 and:35 extend downwardly at each side of the split rollers 25. As shown in Fig. 3, if the belt 13 in the lower run Z4 travels to either side, it wi-ll-be prevented from running of:E the split rollers 25 by engagement of the retaining walls 34 and 35 with the ends of the split rollers.
As described hereinabove, when the belt 13 is subjected to a sufficient tension, the walls 34 and 35 will be retained in the operating condition for containiny the bulk material so tha-t the rollers 22 may be cylindrical. The substantial tension maintained throughout the leng-th of the - belt 13 also makes possible a greater spacing between the support rollers 22 than is possible with a conventional con-veyor belt.
Referring to Figs. 7 and 8, a modified constructionof a conveyor belt 54 is shown having an elongated elastomeric body of resilient material with spaced edges 55 and 56. A
first layer 57 has reinforcing cords 58 laids on a bias of about 45 degrees to transverse axis B-s of the belt and ex'~ends between the edges 55 and 56 of the belt 54. The belt 54 has a load-carrying belt surface 59 on a top cover 62 under which the first layer 57 is located. A second layer 63 of reinforcing cords 64 is positioned under said first layer,57 - with the cords laid at an opposi-te bias angle of 45 degrees to the angle of the cords 58 of -the first layer. The second layer 63 has edges 65 and 66 whi.ch are spaced from the edges 55 and 56 of the belt 54 providing a center portion between the edges 65 and 66. Edge portions 67 and 68 are also pro-vided between the edges 55 and 65 and the edges 56 and 66.
A bottom cover 69 is positioned under the second layer 63 and has a thickness of about 0.07 inches at the center portion. The top cover 62 also has a thickness of about 0.07 inches and the first layer 57 and second layer 63 each have a thickness of about 0.05-inches. A cushioning component 70 is located between the cords 58 and 64 of the first and second layers 57 and 63 and may have a -thickness of about 0.01 to 0.02 inches prior to vulcanization of the be-lt 54. As shown in Figs. 7 and 8, the thickness of the bottom cover 69 at the edge portions 67 and 68 is greater than the thickness at the center portion which further con-tributes to the curling or bending upwards of the edge por-tions.
The cords 58 and 64 of the first and second layers 57 and 63 are of a suitable textile material such as polyester and may be spaced at about 22 ends per inch. The width of the belt is about 34 inches with the center portion having a width of 10 inches and the edge portions 67 and 68 each having a width of about 12 inches in the unstretched condition. The belt 54 is stretchable at least 5 percent and when stretched decreases in width a proportional amount. Also the edge por-tions 67 and 68 bend upwardly to provide retaining walls at the sides of the belt surface 59 in the stretched condition in a similar manner to that described hereinabove for the embodiment of Figs. 4, 5 and 6. The cords 64 of the second layer 63 neutralize the curling action of the cords 58 of the first layer 57 and provide a relatively flat surface 59 between the curled side edges 55 and 56.
Another modification is shown in Fiys. 9 and 10 in which a belt 71 has an elongated elastomeric body with edges 72 and 73 and a belt surface 74 extending between the edges.
The belt 71 has a center portion 75 with margins 76 and 77 spaced from the edges 72 and 73 providing edge portions 78 and 79. The belt surface 74 is on a top cover 82 which has a thickness of about 0.07 inches. The top cover 82 may be of a resilient material having good wear characteristics as indi-cated above. Under the top cover 82 is a first layer 83 of reinforcing cords 84 and 85 in the edge portions 78 and 79, ~L~6~75 respectively. The irst layer 83 extends from the eclges 72 and 73 of the belt 71 to the margins 76 and 77 of the central portion 75 in the edge portions 78 and 79. The cords 84 in the edge portion 78 are laid on a bias to the transverse axis C-C at an angle of 45 degrees in one direc-tion. The cords 85 of the edge portion 79 are laid at an angle of 45 degrees to the transverse axis C-C and at an opposite bias angle -to the cords 84 of the other edge portion 78. Under the first layer 83 is a second layer 86 of.re-inforcing cords 87 and 88 in edge portions 78 and 79 laid at an angle of 45 degrees to the transverse axis C-C but at an - opposite bias angle direction to the cords 84 and 85 of the first layer.
Under the second layer 86 is a third layer 89 of square woven stretch fabric 90.
-~L~6Za~S
The third layer 89 extends from one edge 72 of the belt 71to the other edge 73. The stretch fabric 90 of the third layer 89 has the property of stretching a predetermined distance when subject to tension during the initial stretch-ing of the belt 71 and then its resistance to further elon-gation increases rapidly to resist any appreciable stretching of the belt in operation.
In this modification, the top cover 82 has thick-ness of about 0.07 inches. The first layer 83 is of poly-ester cords spaced at about 22 ends per inch with the firstlayer having a thickness of about 0.05 inches. The second layer 86 also has a thickness of about 0.05 inches and polyester cords spaced at about 22 ends per inch. A bottom cover 93 under the third layer 89 has a thickness of about 0.07 inches. Cushioning components 92 are located between the cords 89 and 85 of the first and second layers 83 and 86 and between the cords 87 of the second layer 86 and the stretch fabric 90 of the third layer 89. The cushioning components 92 may have a thickness of about 0.01 to 0.02 inches prior to vulcanization.
In operation the belt 71 is built and vulcanized in the flat condition as shown in Figs. 9 and 10 with the stretch fabric 90 of the third layer 89 in the unstretched condition. Upon installation of the belt 71 on a conveyor, the belt is initially stretched a predetermined amount of at least 5 percent, at which point further stretching of the belt is stronlgy resisted. During the stretching process, the cords 84, - - --~ ~ !
85, 87 and 88 of the first and second layers 83 and 36 pantograph and bend the edge portions 78 and 79 upwardly at the sides of the belt surface 74 providing retaining walls such as those shown in Figs~ 3 and 5. With the stretch fabric 90 of the third layer 89 -the longitudinal force neces-sary for initial stretching of the belt 71 is less than it would be if the stretching of the belt was limited by layers of reinforcing cord laid on a bias such as that shown in the modifications of Figs. 4 through 8. Also -transverse cords oE
the stretch fabric 90 resist reduc-tion in width of the belt 71 and contribute to -the bending of the edge por-tions 78 and 79.
Referring to Fig. 11, a belt 71' is shown which is identical to the belt of Figs. 9 and 10 except that in the second layer 86' a center portion 94 has been added to fill the space between the margins 76' and 77'. The center portion 94 of the second layer 86' is of square woven stretch fabric 95 having the property of being stretchable upon initial stretching of the belt 71' during installation on the con-veyor and then having a high resistance to further stretchingof the belt in operation. The stretch fabric 95 of the center portion 94 of the second layer 86' may have the same charac-teristics as the stretch fabric 90 of the third layer 89 of the belt 71 sho~n in Figs. 9 and 10. The cushioning component 92' between the cords of the second layer 86' and the stretch fabric of the third layer 89' also extends between the stretch fabric of the second and third layers. In operation, the belt of Fig. 11 is stretchable and will provide upstanding re-tain-ing walls in a similar manner to the belt of Figs. 9 and 10:
however, the belt of Fig. 11 may have greater strength in the longitudinal direction in the s-tretched condition.
- A belt 96 adaptable for movement around curves is shown in Figs. 12, 13 ancl 14. 'l'l~e belt 96 has an elonga-ted elastomeric body with a top portion 97 and a bottom portion 98 connected at a center portion 99. As shown in FicJs. 12 and 13, the top portion 97 has a top cover 102 extending between edges 103 and 104 which may be of a resilien-t material having good wear characteristics. Under the top cover 102 is a first layer 105 of reinforcing cords 106 in eage portions 108 and 109 extending inward from edges 103 and 104 to the center portion 99. The cords 106 in the edge por-tions 108 and 109 are laid at a bias angle of about 45 degrees to the transverse axis D-D.
Under the first layer 105 is a second layer 112 of reinforcing cords 113 coextensive with the cords 106 of the first layer 105. The reinforcing cords 113 are laid at an angle of about 45 degrees to the transverse axis D-D and at an opposite bias angle to the cords 106 of the first layer 105.
Under the second layer 112 is a third layer 115 of transversely extending cords 116 between the edges 103 and 104 of the belt 96. Under the third layer 115 is a middle cover 118 which is connected at the center portion 99 to a middle cover 119 of the bottom portion 98. As shown in Figs.
12, 13 and 14, the bottom portion 98 in the unstretched con-dition preferably has a width less than the width of the top portion 97.
Under the middle cover 119 is a fourth layer 122 of reinforcing cords 123 extendiny -transversely between the edges 103 and 104 of the bottom portion 98 of the bel-t 96.
Preferably the reinforcing cords 123 are of a high modulus material such as steel.
Under the fourth layer 122 is a fifth layer 124 of reinforcing cords 125 positionecl at a bias angle substantially the same as the bias angle of the cords 106 of the first layer 105 and extending from edge-to-edge of the center portion 99.
Under the fifth layer 124 and coextensive therewith is a sixth layer 126 of reinforcing cords 127 laid on a ~ias at an ~1~2~75 angle similar to the angle of cords 113 of the second layer 112.
Under the sixth layer 126 is.a seventh layer ].28 of reinforcing cords 129 extending transversely between the edges 103-and 104. The cords 129 are preferably of high modulus material such as steel. Under the seventh layer 128 is a bottom cover 130 which e~tends from edge 103 to edge 104 of the bottom portion ~8. The transverse cords 129 of -the seventh layer 128 and cords 123 of the fourth layer 122 are spaced longitudinally of the belt 96 sufficiently to permit longitudinal stretching of the belt 96 by an initial amount of at least 5 percent. During this stretching the cords 106 and 113 of the first and second layers 105 and 112 interact with the transverse cords 116 of the third layer 115 and with the elastomeric material of the belt 96 causing the upper surface of the edge portions 108 and 109 to contract laterally and bend upwardly forming retaining walls 131 and 132 for con-taining material being conveyed on a load-carrying belt sur-face 133. Cushioning com~onents 139 are located between the cords of the first and second layers 105 and 112, the second and third layers 112 and 115, the fourth and fifth layers 122 and 124, the fifth and sixth layers 124 and 126, and the sixth and seventh layers 126 and 128.
. The belt 96 is-fabricated and molded in the flat condition shown in Figs. 12 and 13 with the edge portions 108 and 109 of the top portion 97 and bottom portion 98 separated by a sheet or plate of material to form slots 134 and 135 - extending to the center portion 99. In operation the belt 96 is stretchable an initial amount of from 5 to 15 percent due to the pantographing of the reinforcing cords 106 of the first layer 105, reinforcing cords 113 of the second layer 112, cords 125 of -the fifth layer 124, and cords 121 of the sixth layer 126. The in-teraction of the cords 106 of the f~rst layer 105 and the cor~s 113 of the second layer 112 7~i - with the elastomeric material of the belt 96 and the trans-verse cords 116 of the third layer 115 during the stretching of the belt causes the edge portlons 108 and 109 to bend upwardly and form -the walls 131 and 132.
In this embodiment the top cover 102 has a thick-ness of about 0.07 inches a-t the edge portions 108 and 109 and about 0.13 inches at the center portion 99. The re-inforcing cords 106 of the first layer 105 and cords 113 of the second layer 112 may be of polyester and be spaced at about 22 ends per inch. The thickness of the first and second layers 105 and 112 may be about 0.05 inches each. The third layer 115 may also have reinforcing polyester cords 116 spaced at about 22 ends per inch and have a thickness of about 0.05 inches. The middle cover 118 for the top portion 97 may have a thickness of about 0.07 inches.
The middle cover 119 of the bottom portion 98 may also have a thickness of about 0.07 inches. The transverse reinforcing cords 123 and 129 of the Eourth and seventh layers 122 and 128 may be steel strands spaced at eight ends per inch and having a thickness of about 0.1 inches. The fifth and sixth layers 124 and 126 may have reinforcing polyester cords 125 and 127 spaced at about 22 ends per inch with a thickness of about 0.05 inches for each layer. The bottom cover 130 may -have a thickness of 0.07 inches. The cushioning components 139 may have a thickness depending on the thickness of the skim coat on the cords. The cords of polyester have a skim coat of a thickness oE from about 0.01 to 0.02 inches and the - cords of steel have a skim coat of from about 0.01 to 0.03 inches. Therefore the to-tal thickness of the cushioning com-ponents 139 may be from about 0.02 to 0.05 inches.
In operation when the bel-t 96 is clirected around a curve the bottom portion 98 resists transverse deflection of the belt and supports the top portion 97 which has the walls 131 and 132 for re-taining the material on the belt surface S
133. Due to the stretching of the,walls 131 and 132 they will be maintained in position even though the elongation of the belt 96 varies across -the wicl-th of the bel~. Normally pulleys (not shown) are positioned around the edges 103 and 104 of the bottom portion 98 and also under the bottom cover 130 to maintain the configuration of the belt 96 around curves.
- A belt 136 is shown in Figs. 15 and 16 which is similar to the belt 96 shown in Figs. 12, 13 and 14. However~
instead of the fifth and sixth layers 124 and 126 of re-inforcing cords 123 and 125 being positioned at a bias angle to the transverse axis D-D, a separating layer 137 oE square woven stretch fabric 138 extending between the edges of the center portion 99' is positioned between the fourth and seventh layers 122' and 128'. The stretch fabric 138 of the separating layer 137 has the property of stretching a pre-determined distance upon initial stretching during installa-tion of the belt 136 from about 5 to 15 percent and then has a high resistance to further stretching of the belt in opera-tion. In other respects the construction of belt 136 of Figs.
15 ancl 16 is the same as the construction of the belt 96 except there is one less cushioning component 139'. In operation the transverse cords of the stretch fabric 138 and the elastomeric material of the belt 136 interact with the reinforcing cords 106' of the first layer 105' and the cords 113' of the second layer 112' to bend the edge portions 108' and 109' of the top portion 97' upwardly into the shape shown in Fig. 14.
Referring to Figs. 17, 18, 19, 20 and 21 a further modification is shown in which a belt 142 having a construc-tion shown in greater detail in Fig. 19 has edge portiQns 143 and 144 and a center portion 145. The edge portions 143 and 144 are located between the center portion 145 and edges 146 and 147 of the belt 142. The eclge portions 143 and 144 may be divided into outer margins 148 and 149 ad~acent the edges .... . .. . .. . ....... . ... .. . . .
146 and 147 and inner margins 152 and 153 adjacent the center portion 145. The bel-t 142 may be of an elastomeric material and have a construction similar to the construction described hereinabove for the belt 13 shown in Figs. 4 and 5 except that the belt 142 shown in Fig. 19 has edge portions 143 and 144 of greater wid-th than the edge portions of the belt 13 by the width of the outer margins 148 and 199. Also the third layer 43' extends beyond the ends of the first and - second layers 32' and 33' so that when the belt 142 is in the stretched condition as shown in Fig. 18 the edye portions 143 and 144 will overlap to enclose the space above the load-carrying belt surface 31l. With the construction of the belt 142 the thickness of the belt at the outer margins 148 and 149 is reduced which also reduces the weight at the edges 146 and 147.
As shown in Figs~ 19 and 20 connecting means such as channels 154 and 155 are mounted on the bottom cover 53' at the outer margin 149 and ribs 156 and 157 are mounted on the surface 31' of the top cover 38' at the other outer margin 148 for matching engagement upon pressing of the margin 148 against the margin 149 by suitable means such as rollers 158 and 159. As shown in Fig. 17 the rollers 158 and 159 may be mounted on a frame 162 at one end of a con-veyor 163 close to the tail pulley 164. After the load is applied to the belt surface 31' and the belt 142 takes the configuration shown in Fig. 18 the ribs 156 and 157 may be pushed into engagement with the channels 154 and 155 provid-ing a sealed chamber within the belt for conveying material.
At the discharge end of the conveyor 163, discharge pulley 165 tends to spread the walls 34' and 35' and as shown in Fig. 21 separating rollers 166 and 167 may be used to assist in this ac-tion and pull the ribs 156 and 157 out oE the channels 154 and 155 so that the material conveyed on the surface 31 may be discharged and the return run 168 carried 75~
back to the tail pulley 164 by suitable rollers 169 as shown in Fig. 18. The upper run 170 may be supported by support rollers 172. As shown in Fig. 18 a roller frame 173 mounted on a supporting surface such as the ground or hung from the roof supports the rollers 169 and 172.
In operation the belt 142 is mounted on the con-veyor 163 under tension in a similar manner to that described hereinabove for the other modifications. As the belt 142 is driven from the tail pulley 164 to the discharge pulley 165 the rollers 158 and 159 will urge the ribs 156 and 157 into engagement with the channels 155 and 154. Then at the dis-charge end the discharge pulley 165 spreading -the walls 34' and 35' and supplemented by the separating rollers 166 and 167 will pull the ribs 156 and 157 out of the channels 154 and 155 and permit the discharge of the material at the dis-charge pulley 165. The elastomeric material of the belt 142 and the reinforcing cords may be the same as that described hereinabove for the belt 13 of Figs. 4, 5 and 6. The channels 154 and 155 and ribs 156 ana 157 may be of a resilient ma-terial such as nylon which is adhered to the belt 142 by a suitable adhesive.
Referring to Fig. 22 a belt 174 has a construction similar to the construction of the belt 71' shown in Fig. 11 except that the first layer 83 " and second layer 86 " extend over only inner margins 175 and 176 adjacent the central portion 75 " . Outer margins 177 and 178 extend beyond the ends of the first and second layers 83 " and 86 " and are adjacent the edges- 72 " and 73 " of the belt 174. Also con-necting means such as channels 179 and 182 are mounted on the bottom cover 93 " at the outer margin 178 and ribs 183 and 184 are mounted on the surface 74 " of the top cover 82 " at the outer margin 177 for matching engagement upon pressing of the margin 177 against the margin 178 by suitable means such as the rollers 158 and 159 shown in Fig. 20.
In operation the belt 174 is mounted on a conveyor similar to the conveyor 163 shown in Fig. 17 and operated under tension in the same manner as that described for the belt 142 shown in Figs. 17, 18, 19 and 20.
In Figs. 19 and 21 the belts 142 and 174 have outer margins 148, 149, 177 and 178 which are shown substantially equal in width to the corresponding inner margins 152, 153, 176 and 175. I-t is evident that the outer margins may have a width substantially greater than the width of the inner margins and be in relation to the wid-th of -the center por-tions 145 and 75" so that the edges will overlap to enclose the load carried by the belts.
While certain representative embodiments and details have been shown for the purpose of illustrating the inven-tion it will be apparent to those skilled in the art that various changes and modifications may be made therein without depart-ing from the invention.
Claims (32)
1. A conveyor belt which is longitudinally stretchable at least 5 percent, said belt embodying belt narrowing means responsive to longitudinal stretching of said belt, and means resisting narrowing of said belt, said belt narrowing means being closer to the load-carrying surface of said belt than said means resisting narrowing, whereby ten-sion on the belt generates transverse forces bending the edges of the belt to form retaining walls for the load car-ried by the belt.
2. A belt in accordance with claim 1 in which said belt narrowing means includes tension-resisting elements at a bias angle to both the longitudinal and transverse directions of said belt, and said means resisting narrowing being stretchable in the longitudinal and transverse directions and resistant to a change in dimension in the transverse direc-tion of said belt.
3. A stretchable conveyor belt comprising an elongated elastomeric body having spaced-apart edges, edge portions along said edges, a load-carrying belt surface on one side of said body extending between said edges, said belt being stretchable at least 5 percent when subjected to lon-gitudinal forces in tension, belt narrowing means responsive to stretching of said belt whereby tension on said belt gener-ates transverse forces in a direction to reduce the width of the belt, and resistance means positioned in said belt to selectively resist said transverse forces generated by said narrowing means and bend said edge portions of said belt by interaction with said narrowing means providing retaining walls at said edges for the load carried by said belt surface.
4. A belt in accordance with claim 3 wherein said belt narrowing means includes a layer of reinforcing cords laid on a bias to the transverse axis of the belt.
5. A belt in accordance with claim 4 wherein said cords are laid on a bias in the range of from 45 to 60 degrees to a transverse axis of the belt.
6. A belt in accordance with claim 5 wherein said body has a center portion spaced from said edges, a pair of said edge portions between said center portion and said edges, a second layer of reinforcing cords having substantially the same width as said center portion, said first-mentioned layer of reinforcing cords being laid at a bias to the transverse axis and extending from one of said edges to the other of said edges at a position between said second layer and said load-carrying belt surface.
7. A belt in accordance with claim 3 wherein said belt contains overlapping layers of reinforcing cords and cushioning components of resilient material located between the cords of said layers to permit relative angular movement of the cords of the overlapping layers during stretching of said belt.
8. A belt in accordance with claim 3 wherein said resistance means includes the resilient material of said elastomeric body and said narrowing means includes a layer of reinforcing material, said layer of reinforcing material separating said resilient material into at least two portions with the upper portion between said layer of reinforcing material and said load-carrying belt surface being of less thickness than the lower portion on the other side of said layer of reinforcing material whereby the reduction in width between said edges at said belt surface is greater than the reduction in width at said lower portion causing said edge portions to curl up and away from said belt surface.
9. A belt in accordance with claim 4 wherein said layer of reinforcing cords extends from one of said edges to the other of said edges in a first layer under said belt sur-face, a second layer of reinforcing cords coextensive with and positioned under said first layer laid at an opposite bias angle to the cords of said first layer, a third layer of reinforcing cords coextensive with and positioned under said second layer formed of parallel cords extending substantially transversely of the belt, a fourth layer of reinforcing cords under said third layer of cords having layer edges spaced from said edges of said belt and positioned under said third layer laid on a bias at substantially the same angle as the cords of said first layer, and a fifth layer of reinforcing cords coextensive with and positioned under said fourth layer laid on a bias at substantially the same angle as the cords of said second layer.
10. A belt in accordance with claim 9 wherein the cords of said first, second, fourth and fifth layers are laid on a bias of about 55 degrees to a transverse axis of the belt.
11. A belt in accordance with claim 10 wherein the cords of said first through fifth layers are of polyester spaced at about 22 ends per inch with a thickness of about 0.05 inches for each layer.
12. A belt in accordance with claim 11 wherein said elastomeric body has a top layer of wear-resistant material between said first layer and said belt surface on one side of said body, a bottom layer of resilient material under said fifth layer, said top layer having a thickness of about 0.06 inches and said bottom layer having a thickness of about 0.06 inches and the total thickness of said belt in the vulcanized condition being about 0.37 inches.
13. A belt in accordance with claim 4 wherein said layer of reinforcing cords extends only part way across the belt and constitutes a first layer under said belt surface extending from the edges towards the middle of the belt but being separated by a center portion of the belt, said reinforcing cords of said first layer being laid on a bias at an angle to a transverse axis at a first edge portion of the belt adjacent one of the edges, said first layer having cords at a second edge portion of the belt adjacent the other of said edges laid at an opposite bias angle to the cords at said first edge portion, a second layer coextensive with and positioned under said first layer having reinforcing cords laid at an opposite bias angle to the cords of said first layer, a third layer of stretch fabric under said second layer and extending from one of said edges to the other of said edges, said stretch fabric of said third layer having the property of stretching a predetermined distance when sub-ject to tension during installation of the belt and then having a rapidly increasing resistance to further elongation of the belt in operation.
14. A belt in accordance with claim 13 wherein the cords of said first and second layers are laid on a bias of about 45 degrees to the transverse axis of the belt.
15. A belt in accordance with claim 14 wherein the cords of said first and second layers are of polyester and are spaced at about 22 ends per inch with a thickness of about 0.05 inches for each layer.
16. A belt in accordance with claim 15 wherein said elastomeric body has a top layer of wear-resistant material between said first layer and said belt surface on one side of said body, a bottom layer of resilient material under said third layer, said top layer having a thickness of about 0.07 inches and said bottom layer having a thickness of about 0.07 inches.
17. A belt in accordance with claim 13 wherein said second layer has a center portion of stretch fabric having the property of being stretchable upon initial stretch-ing of the belt when subject to tension during installation on the conveyor and then having a rapidly increasing resist-ance to further elongation of the belt in operation.
18. A belt in accordance with claim 17 wherein said stretch fabric of the center portion of said second layer is of the same material as the stretch fabric of said third layer.
19. A belt in accordance with claim 3 wherein said elastomeric body has a top portion containing said narrowing means responsive to stretching of said belt, and said top portion at said edges being bendable to form said retaining walls upon stretching of said belt, a bottom por-tion reinforced by transversely extending reinforcing means to resist transverse deflection of said belt when passing around a curve, said bottom portion being connected to said top portion at a center portion of said belt spaced from said edges to permit bending of said top portion at said edges upon stretching of said belt.
20. A belt in accordance with claim 19 wherein said bottom portion includes transversely extending reinforc-ing members at spaced-apart positions longitudinally of said belt.
21. A belt in accordance with claim 20 wherein said reinforcing members include at least two spaced layers of reinforcing cords of a material having a high modulus of elasticity.
22. A belt in accordance with claim 19 wherein said narrowing means of said top portion includes a first layer of reinforcing cords positioned under said belt surface and extending from the edges towards the middle of the belt but being separated by a center portion of the belt, said reinforcing cords of said first layer being laid on a bias at an angle to a transverse axis of said belt, a second layer coextensive with and positioned under said first layer having reinforcing cords laid at an opposite bias angle to the cords of said first layer, a third layer of reinforcing cords under said second layer and extending from one of said edges to the other of said edges, said cords of said third layer being substantially transverse of the belt, a fourth layer posi-tioned under said third layer and in said bottom portion of said belt, said cords of said fourth layer extending trans-versely of the belt and being of a material having a high modulus of elasticity, a fifth layer of reinforcing cords under said fourth layer, said cords of said fifth layer being laid on a bias at an angle to the transverse axis of the belt, a sixth layer under said fifth layer, said sixth layer being coextensive with said fifth layer, said cords of said sixth layer being laid at an opposite bias angle to the cords of said fifth layer, a seventh layer under said sixth layer, said cords of said seventh layer being of a material having a high modulus of elasticity and extending transversely of said belt whereby said belt is stretchable an initial amount due to the pantographing of the reinforcing cords of said fifth and.
sixth layers and said first and second edge portions are bendable upwardly to provide retaining walls due to the inter-action of said first and second layers with the resilient material of said elongated elastomeric body.
sixth layers and said first and second edge portions are bendable upwardly to provide retaining walls due to the inter-action of said first and second layers with the resilient material of said elongated elastomeric body.
23. A belt in accordance with claim 22 wherein said first, second, third, fifth and sixth layers have re-inforcing plies of polyester cords spaced at about 22 ends per inch and a thickness of about 0.05 inches, said fourth and seventh layers have reinforcing cords of steel spaced at about 8 ends per inch with a thickness of about 0.1 inches and said reinforcing cords in layers one, two, five and six are laid at an angle of about 45 degrees to the transverse axis of said belt.
24. A belt in accordance with claim 19 wherein said narrowing means of said top portion includes a first layer of reinforcing cords positioned under said belt surface and extending from the edges towards the middle of the belt but being separated by a center portion of the belt, said reinforcing cords of said first layer being laid on a bias at an angle to the transverse axis of said belt, a second layer coextensive with and positioned under said first layer and having reinforcing cords laid at an opposite bias angle to the cords of said first layer, a third layer of reinforcing cords under said second layer and extending from one of said edges to the other of said edges, said cords of said third layer being substantially transverse of the belt, a fourth layer positioned under said third layer and in said bottom portion of said belt, said cords of said fourth layer extend-ing transversely of the belt and being of a material having a high modulus of elasticity, a fifth layer of square woven stretch fabric located in said center portion under said fourth layer, said stretch fabric of said fifth layer having the property of stretching a predetermined distance when sub-ject to tension during installation of the belt and then having a rapidly increasing resistance to further elongation of the belt in operation, a sixth layer under said fifth layer, said cords of said sixth layer extending transversely of said belt whereby said belt is stretchable an initial amount due to the stretching of the stretch fabric of said fifth layer and said first and second edge portions of said top portion being bendable upwardly to provide retaining walls due to the interaction of said first and second layers with the resilient material of said elongated elastomeric body and the transverse cords of said third layer.
25. A belt in accordance with claim 4 wherein said edge portions are of sufficient width and said interaction of said narrowing means and said resistance means is suffi-cient to bend said edge portions of said belt until said retaining walls substantially enclose the space above said load-carrying belt surface when said belt is in the stretched condition.
26. A belt in accordance with claim 25 wherein each of said edges has a connecting means for engaging the other of said edges for enclosing the space above said belt surface during operation of the belt in the stretched condi-tion.
27. A belt in accordance with claim 25 wherein said body has a center portion positioned between said edge portions, said narrowing means including a first layer of reinforcing cords positioned under said belt surface and extending from within one of said edge portions into the other of said edge portions, said reinforcing cords of said first layer being laid on a bias at an angle to a transverse axis of the belt, a second layer coextensive with and posi-tioned under said first layer having reinforcing cords laid at an opposite bias angle to the cords of said first layer, a third layer of transverse reinforcing cords extending from one of said spaced-apart edges to the other of said edges, a fourth layer of reinforcing cords having substantially the same width as said center portion, said cords of said fourth layer being laid on a bias at an angle to said transverse axis, a fifth layer of reinforcing cords coextensive with and positioned under said fourth layer having reinforcing cords.
laid at an opposite bias angle to the cords of said fourth layer.
laid at an opposite bias angle to the cords of said fourth layer.
28. A belt in accordance with claim 27 wherein each of said edge portions has an inner margin adjacent said center portion and an outer margin adjacent one of said edges, said first and second layers extending through said inner margin but terminating short of said outer margin of each of said edge portions, said transverse reinforcing cords extending through both said inner and outer margins of each of said edge portions and a bottom cover positioned under said fifth layer and the ends of said third layer having a relatively constant thickness to reduce the thickness of said belt at said outer margin of each of said edge portions.
29. A belt in accordance with claim 27 wherein the angle of said reinforcing cords of said first, second, fourth and fifth layers relative to said transverse axis is about 55 degrees.
30. A belt in accordance with claim 25 wherein said body has a center portion positioned between said edge portions and each of said edge portions has an inner margin adjacent said center portion and an outer margin adjacent one of said edges, said narrowing means including a first layer of reinforcing cords positioned under said belt sur-face and in said inner margin of each of said edge portions, said reinforcing cords of said first layer at one of said margins being laid on a bias at an angle to a transverse axis of said belt, said reinforcing cords of said first layer in the other of said margins being laid at an opposite bias angle to the cords in said first-mentioned margin, a second layer of reinforcing cords coextensive with and posi-tioned under said first layer, said reinforcing cords of said second layer in said inner margins being laid on a bias at an opposite bias angle to the cords of said first layer, said second layer including square woven stretch fabric in said center portion having the property of stretching a pre-determined distance under tension during installation of the belt and then rapidly increasing resistance to further elongation of the belt in operation, a third layer of stretch fabric under said second layer and extending through said center portion and said inner margin of each of said edge portions but terminating short of said outer margin.
31. A belt in accordance with claim 30 including a bottom cover positioned under said third layer and has a relatively constant thickness in said edge portions to reduce the thickness of the belt at said outer margins.
32. A belt in accordance with claims 27 or 31 wherein connecting means for each of said edges are mounted on said edge portions for engagement upon enclosing the space above said belt surface. during operation of the belt in the stretched condition.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384738A CA1162875A (en) | 1981-08-27 | 1981-08-27 | Stretchable load-retaining conveyor belt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384738A CA1162875A (en) | 1981-08-27 | 1981-08-27 | Stretchable load-retaining conveyor belt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162875A true CA1162875A (en) | 1984-02-28 |
Family
ID=4120819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000384738A Expired CA1162875A (en) | 1981-08-27 | 1981-08-27 | Stretchable load-retaining conveyor belt |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1162875A (en) |
-
1981
- 1981-08-27 CA CA000384738A patent/CA1162875A/en not_active Expired
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