Conveyor belt for roller conveyor having grooved rollers and associated conveyor

Abstract

A conveyor belt (100) for a roller conveyor having rollers with grooves, the grooves being made of steel or plastic, the belt comprising:-an elastomer-based body (102) comprising a back side portion (104) and a ventral side portion (106), the ventral side portion being formed by a single toothing, the outer surface of the toothing having a convex shape, the convex shape is configured to be jointed with the groove of the roller; -a set of tension cords (110) embedded in the body (102) and located between the dorsal portion (104) and the ventral portion (106) of the body; and-a cover layer (112) arranged on the outer surface of the toothing, the cover layer, together with the shape of the outer surface of the toothing, defining a coefficient of friction with the groove of the roller, the coefficient of friction being non-zero and less than or equal to 0.8.

Description

[0001] Technical field of the present invention

[0002] The invention relates to a conveyor belt for a roller conveyor having grooved rollers. The invention also relates to a grooved roller conveyor equipped with such a belt. Background Art

[0003] Roller conveyors are widely used in the field of logistics and cargo flow to route and sort various items, especially parcels. Generally speaking, these conveyors include a number of rollers that are driven to rotate by a drive element via a transmission element. There are different types of rollers and just as many transmission elements, each with its own specific requirements. In particular, roller conveyors with rollers with grooves, which are usually circular, are very common. For example, they are Figures 1 to 4 shown.

[0004] Figure 1 and Figure 2 The conventional construction of a circular grooved roller conveyor is shown, i.e. Figure 1 The linear conveyor 1a shown and the Figure 2 The curved section of conveyor 1b is shown.

[0005] Typically, each roller 10 of the conveyor 1a, 1b comprises, at least at one of its longitudinal ends, a groove 12 with a circular groove bottom 14. A round belt 2 (i.e., a round belt with a disc-shaped cross section) engages in these grooves 12 to drive the rollers 10. These belts are usually made of polyurethane, are inexpensive, and are easy to fit into the grooves.

[0006] In operation, a driving roller rotates an adjacent roller 10 (referred to as a driven roller) via a belt 2. The driving roller is similar to the driven roller, except that it is equipped with a motor that allows it to start on its own. The driving roller then rotates the first driven roller via a first belt 2, which itself can drive the second driven roller via a second belt, and so on.

[0007] To maximize torque transmission between the two rollers, the belt 2 must rest on the bottom 14 of the trough 12 with the largest possible contact surface, while minimizing contact with the sides 16 of the trough 12. Contact with the sides of the trough can have several detrimental consequences. First, because there are two contact surfaces between the belt and the trough, and these two contact surfaces are located at significantly different distances from the roller's axis of rotation, the belt is subjected to two speeds that differ significantly. This increases belt deformation and wear. Second, it makes the belt more susceptible to overturning. These detrimental conditions are particularly common in curved sections of the conveyor, as the bend forces the belt to contact one side of the trough.

[0008] Document US-A1-2009 / 107809 describes a typical example of a roller conveyor.

[0009] Next, we need to distinguish between different types of roller conveyors.

[0010] Figure 3 A first type of roller 10, made of steel, is shown. This roller includes grooves 12 formed directly into the roller 10 at one end. These grooves could, for example, be pressed into the roller. In this case, there is a zone Z1 for the passage of packages, which extends over the entire length of the roller 10, encompassing the grooves 12 and the conveying zone Z2 where the circular belts 2 are located. While this configuration allows for the widest possible passage zone Z1, problems can arise if a package comes into contact with one of the belts 2. In the event of a collision between a belt 2 and a package, the belt 2 could break free from the grooves 12 in the roller 10, potentially causing the conveyor to stop.

[0011] In order to prevent this from happening, the cross-sectional diameter of the circular strip 2 is chosen to be strictly smaller than the depth of the groove 12. For example, for a groove 10 mm (millimeters) deep, the diameter of the strip cross section is 6 mm.

[0012] However, this limits the contact surface between the belt 2 and the bottom 14 of the groove 12 and therefore limits the torque that can be transmitted by the belt between the two rollers.

[0013] Alternatively, as Figure 4 As shown, there are rollers with drive heads 18 mounted at one end of the rollers 10. The drive heads 18, which are usually made of plastic, have the advantage of having a conveying zone Z2 closer to the ends of the rollers 10 and the side profiles of the conveyors 1a, 1b. In this way, it is possible to separate the zone Z2 of the belt from the zone Z1 in which the parcels to be transported pass over the rollers, thereby limiting or even preventing the parcels from coming into contact with the belt 2. However, for the same conveyor width, Figure 4 The rollers in the Figure 3 The rolls in the small package.

[0014] In practice, current round belts have relatively poor torque transmission and poor service life, especially in curved sections of the conveyor where they can more easily roll over, leading to accelerated wear or even breakage (especially at belt welds).

[0015] Documents US-A1-2002 / 03997, US-A1-2014 / 323257, JP-A-S53-37266, EP-A1-3045771 or GB-A-697901 show other types of belts that can be used for roller grooves.

[0016] The invention also aims to propose a conveyor belt for a grooved roller conveyor which does not have at least one of the above-mentioned disadvantages.

[0017] Another object of the present invention is to provide a conveyor belt for roller conveyors with grooved rollers, which conveyor belt offers improved performance in terms of the torque that can be transmitted between the two rollers.

[0018] Another object of the present invention is to propose a conveyor belt for roller conveyors with grooved rollers which also limits the risks of the belt turning over, in particular in curved sections of the conveyor. Summary of the Invention

[0019] Therefore, a conveyor belt for a roller conveyor having rollers with grooves, the grooves being made of steel or plastic, is proposed, the belt comprising:

[0020] - a body based on an elastomer comprising a dorsal part and a ventral part, the ventral part being formed by a single tooth

[0021] The outer surface of the portion has a convex shape configured to mate with the groove of the roller;

[0022] - a set of tension cords embedded in the body and located between the dorsal portion and the ventral portion of the body;

[0023] and

[0024] a covering layer arranged on the outer surface of the toothing, which covering layer, together with the shape of the outer surface of the toothing, defines a coefficient of friction with the groove of the roller, this coefficient of friction being non-zero and less than or equal to 0.8.

[0025] The present invention thus ensures improved belt torque and stability. Indeed, during use, the belt's contact surface with the bottom of the roller's groove is large, thanks to the convex shape of the belt's teeth, which adapts to the concave shape of the groove. Furthermore, the combination of this convex shape of the teeth and the covering layer applied to their outer surfaces means that the belt's coefficient of friction in the groove can be set to a controlled value. By controlling the coefficient of friction and providing a rope that improves the belt's tensile modulus, control over the belt's torque can be maintained. This also reduces the risk of the belt tipping over as it extends along one side of the groove, particularly in curved sections of the conveyor.

[0026] The belt according to the invention may comprise one or more of the following features, which may be separated from one another or combined with one another:

[0027] - the coefficient of friction is greater than or equal to 0.3;

[0028] - the set of tension cords defines a tensile modulus of the belt between 500 N and 1500 N, advantageously between 800 N and 1500 N and preferably between 800 N and 1200 N;

[0029] - the ropes of the set of ropes are made of a polyamide-based or polyester-based material;

[0030] - the covering layer partially embedded in the teeth is chosen from a braided fabric, a woven fabric, a non-woven fabric or a fiber group;

[0031] The cover layer is made of a material selected from the group consisting of polyamide, polyester, cellulose fibers such as cotton, cellulose fibers and polyurethane

[0032] A mixture of esters, or a combination of the above materials;

[0033] - the body is made of a material selected from the group consisting of ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane, or natural rubber;

[0034] - the body is made of a material chosen from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the covering layer is a film of at least partially cross-linked thermoplastic material comprising at least 30% of polyethylene, the thermoplastic film covering the outer surface of the tooth;

[0035] The membrane comprises particles and / or fibers of graphite, molybdenum disulphide and / or polytetrafluoroethylene.

[0036] The invention also relates to a conveyor comprising a plurality of rollers having grooves made of steel or plastic, wherein the rollers are connected together in pairs by means of the above-mentioned belt so that the cover of the belt is in contact with the grooves of the rollers.

[0037] The conveyor according to the present invention may include one or more of the following features, which may be separated from each other or combined with each other:

[0038] - the height of the strip is strictly less than the depth of the groove receiving the strip;

[0039] - the grooves of the roller are made of a plastic material chosen from polyamide, polypropylene, or a material based on an embedded thermoplastic resin or

[0040] Composite materials of fibers in thermosetting resins;

[0041] The belt is mounted between the rollers with a laying tension between 60 and 100 N / strand. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention will be better understood with the aid of the following description, given by way of example only, and made with reference to the accompanying drawings, in which:

[0043] Figure 1 shows a schematic diagram of a linear roller conveyor according to the prior art,

[0044] Figure 2 shows a schematic diagram of a curved roller conveyor according to the prior art,

[0045] Figure 3 shows a schematic diagram of a longitudinal cross section of a grooved roller with a conventional drive belt according to the prior art,

[0046] Figure 4 A schematic diagram showing a longitudinal cross section of a grooved roller with another shape of a conventional drive belt according to the prior art,

[0047] Figure 5 shows a schematic cross-sectional view of a conveyor belt for a grooved roller conveyor according to the present invention,

[0048] Figure 6 Shown Figure 5 Schematic perspective view and partial cross section of the belt shown,

[0049] Figure 7 shows a schematic cross-section of a belt according to the invention, in particular illustrating the different permeabilities of the covering layer at the level of the outer surface of the teeth of the body of the belt,

[0050] Figure 8 shows a schematic cross-sectional view of an embodiment of a belt according to the invention, in particular defining the dimensions of the belt,

[0051] Figure 9 Shown Figure 8 Photographic view of a cross section of the band in;

[0052] Figure 10 Schematic diagram showing a longitudinal cross-section of a mandrel around which the belt material is placed and a braiding sleeve used in the manufacture of a belt according to an example of an embodiment,

[0053] Figure 11 A schematic diagram showing a longitudinal cross section of a braided sleeve placed on a belt material, which itself is arranged on Figure 10 On the central axis,

[0054] Figure 12 Shown is the insertion into the mold Figure 11 A schematic diagram of a longitudinal cross section of an object in

[0055] Figure 13This is a schematic diagram of an experimental setup for measuring the friction coefficient of a belt using a pulley.

[0056] Figure 14 is a graph comparing the slip as a function of the torque transmitted by a conventional belt known in the prior art and the slip as a function of the torque transmitted by a belt in an exemplary embodiment,

[0057] Figure 15 A schematic diagram showing a longitudinal cross section of a belt according to the invention is shown, which is mounted on a Figure 3 The grooved roller shown, and

[0058] Figure 16 A schematic diagram showing a longitudinal cross section of a belt according to the invention is shown, which is mounted on a Figure 4 On the roller shown with grooves. DETAILED DESCRIPTION

[0059] In the following, reference is made to a conveyor belt for a roller conveyor having grooved rollers such as those described above for illustrating the prior art and in Figures 1 to 4 Those rollers shown in .

[0060] Figure 5 and Figure 6 Shown are a cross-sectional view and a perspective view and a partial cross-section, respectively, of a conveyor belt 100 for conveyors 1a, 1b having rollers 10 with grooves 12. "Grooved" is understood to mean any groove having a generally concave cross-section, such as a circular groove (i.e., a groove bottom in the shape of an arc of a circle, or a groove having an elliptical or oval bottom).

[0061] The belt 100 includes an elastomeric-based body 102 , a set of tension cords 110 , and a cover layer 112 .

[0062] The elastomer-based body 102 includes a backside portion 104 .

[0063] The elastomer-based body 102 also includes a ventral portion 106 formed by a single toothing, the outer convex surface of which is configured to cooperate with the groove 12 of the conveyor 1a, 1b roller 10. The outer convex surface of the toothing can be, for example, arcuate, elliptical or oval, depending in particular on the shape of the recess forming the groove. Advantageously, when the groove of the roller is a circular groove, the outer surface of the toothing of the ventral portion 106 forms a circular arc.

[0064] Furthermore, this convex surface helps define the coefficient of friction (COF) between the belt 100 and the groove 12 of the roller 10 in which the belt 100 is configured to fit. In practice, the higher the COF, the greater the torque that can be transmitted. However, a higher COF also increases the risk of the belt 100 flipping, particularly in curved sections of the conveyor. Conversely, a lower COF reduces the torque that can be transmitted, thereby limiting the torque that can be transferred from one roller to the other.

[0065] The control of this parameter is discussed below.

[0066] Furthermore, the dorsal portion 104 and the ventral portion 106 of the body 102 may, but need not necessarily, be connected by a lateral portion 108 .

[0067] The belt 100 also includes a set of tension cords 110. The cords 110 are embedded in the body 102 and are located between the dorsal portion 104 and the ventral portion 106 of the body 102. The cords 110 increase the tensile modulus of the belt 100. Thus, the cords extend along the length of the belt and are arranged adjacent to each other across the width of the body 102. In particular, the cords 110 of the set can be made of a material selected from polyamide (PA) or polyester. Thus, for the application in question, the cords allow for greater torque transmission while maintaining a very limited elongation of the belt 100.

[0068] The structure of each cord 110, the number of cords 110 arranged across the width of the belt 100, and the choice of material of which these cords are composed are variable and depend on the tensile modulus required of the belt 100 to ensure torque transmission while limiting the elongation of the belt 100. The general effect of the presence of such cords 110 is to allow higher torque transmission, especially compared to known round belts (typically made of polyurethane) that do not have cords for this type of conveying application.

[0069] Advantageously, the tensile modulus of the tape is chosen between 500 N (Newtons) and 1500 N. Even more advantageously, the tensile modulus is between 800 N and 1500 N, and preferably between 800 N and 1200 N.

[0070] The belt 100 also includes a cover layer 112 disposed on the outer surface of the teeth. The cover layer 112, together with the shape of the teeth, helps define the coefficient of friction (COF) between the belt 100 and the steel roller 10 or the plastic drive head 18 of the roller 10.

[0071] The cover layer 112 may generally be selected from a braided fabric, a woven fabric, a nonwoven fabric, or an assembly of fibers.

[0072] In this case, the elastomeric body 102 of the belt may be made of a material selected from, but not limited to, ethylene-propylene-diene monomer (EPDM), ethylene-propylene copolymer (EPM), polybutadiene (BR), polyurethane (PU), or natural rubber.

[0073] In this case, the cover layer 112 may be made of a material generally selected from the group consisting of polyamide, polyester, cellulose fibers (especially cotton), a mixture of cellulose fibers and polyurethane (especially a mixture of cotton and polyurethane), or a combination of the above materials.

[0074] In particular, the cover layer 112 may be a polyamide braid or a cotton fabric blended with polyurethane.

[0075] In this case as well, a portion of the cover layer 112 is embedded in the toothing.

[0076] In this case, the coefficient of friction is associated with various parameters such as the type of covering layer (e.g., braided or woven fabric), the nature of its material (e.g., polyamide), its grammage, or even its permeability τ into the ventral portion 106 at the level of the outer surface of the teeth. This also depends on the nature of the elastomer and its performance.

[0077] The coefficient of friction between elastomers and steel or plastic is particularly high, typically exceeding 1.5. Depending on the selections made, the parameters used to characterize the cover layer 112 described above allow for a reduction in the coefficient of friction (compared to the same surface without the cover layer 112) and, therefore, control of the coefficient of friction. Given the number of parameters, there are numerous ways to define the coefficient of friction. From a practical perspective, one can first select the type of cover layer 112 (braided, woven, etc.), then the material from which it is made (polyamide, polyester, etc.), the grammage of the cover layer (the higher the grammage, the more of the outer surface the cover layer 112 covers, and vice versa), and finally, the penetration rate of the cover layer into the teeth. This penetration rate, τ, is defined as the proportion of the total thickness of the cover layer 112 that is embedded in the teeth of the elastomer-based body 102. Locally, this penetration rate, τ, can vary from one point to another on the belt 100, so an average penetration rate, τ, over the entire belt 100 is considered. In practice, the penetration rate, τ, will be non-zero and strictly less than 100%, with its exact value depending on other parameters. The choice of these parameters will also depend on the properties of the elastomer used.

[0078] Specific examples of embodiments will be given below.

[0079] Figure 7 It is intended only to illustrate the concept of the permeability τ of the cover layer 112 from the outer surface of these teeth into the teeth, the cover layer 112 considered here is a woven fabric. Figure 7 On the left side, where the permeability τ is zero (0%), the woven fabric 112 does not penetrate the body 102 at all. Figure 7 On the right side, with a permeability τ of 100%, the woven fabric 112 is completely embedded in the body 102 (right). Figure 7 In the middle, we show various cases where the permeability τ is non-zero and strictly less than 100%.

[0080] Alternatively, the cover layer 112 may be a film of partially cross-linked thermoplastic material comprising at least 30% polyethylene (PE), which covers the outer surface of the teeth. It will be appreciated that the thermoplastic film cannot penetrate the teeth.

[0081] In this case, the body 102 of the belt 100 is advantageously based on an ethylene-α-olefin elastomer, in particular EPDM or EPM.

[0082] The thermoplastic film may comprise between 30% and 90% polyethylene, advantageously between 50% and 90% polyethylene, and preferably between 75% and 90% polyethylene.

[0083] The polyethylene in the film is co-crosslinked with the elastomer (e.g., EPDM or EPM) due to the presence of peroxide or other crosslinking agents. This helps the film adhere to the elastomer.

[0084] Thermoplastic films can be made from a mixture of polyolefins containing homopolymers or copolymers comprising ethylene. Ethylene copolymers include ethylene / α-olefin copolymers, ethylene / unsaturated ester copolymers, ethylene / acrylate / acrylic acid copolymers, ethylene / methacrylic acid copolymers, and polyethylene-ethylene octene copolymers. Thermoplastic films can also be based on low density polyethylene.

[0085] The thickness of the thermoplastic film may be between 10 μm (micrometers) and 500 μm, more particularly between 50 μm and 200 μm.

[0086] Advantageously, the thermoplastic film also comprises particles and / or fibers of graphite, molybdenum disulfide and / or polytetrafluoroethylene (PTFE), which among other things influence the coefficient of friction.

[0087] The particles may have a particle size between 15 μm and 200 μm, advantageously between 30 μm and 100 μm, more particularly between 30 μm and 90 μm.

[0088] The type of film mentioned above for the cover layer 112 is known per se to a person skilled in the art, so that its production does not cause any difficulties. However, it is not used for the application considered here.

[0089] Examples of embodiments of the belt according to the invention

[0090] In the following, reference Figure 5 and Figure 8 , showing an example of how an embodiment of belt 100 may be used.

[0091] The elastomer-based body 102 is made of peroxide-cured ethylene-propylene-diene monomer (EPDM) having a hardness between 75 Shore A and 85 Shore A due to the presence of peroxide in EPDM, which affects the coefficient of friction. The EPDM is selected to have a viscosity of 100 Mooney value (ML(1+4) at 100°C). The viscosity is determined according to ISO 289-1, which specifies the test temperature (100°C), the sample preheating time before the start of shear (1 minute), and the shear time (4 minutes).

[0092] In this example of embodiment, the belt 100 has the following definition and Figure 8 The body 102 has a thickness or height H of 2.3 mm and a width L of 6 mm. The single convex tooth of the body 102 is in the shape of an arc of a circle with a diameter D of 10 mm.

[0093] The set of cords 110 embedded in the body 102 includes nine cords 110. The cords 110 have a diameter d of 0.6 mm and their centers are laterally separated by a pitch p of 0.7 mm. The center of each cord 110 is also located at a distance h of 0.7 mm from the back portion 104 of the belt 100.

[0094] Each rope 110 is made of polyamide (PA), in particular polyamide 6-6 (PA66) of 940x1x2, ie the fineness of each thread is 940 dtex (dtex), ie 940x10 -7 kg / m (kilograms / meter), and each wire is first wound individually and then wound around each other. Each rope 110 also has 400MPa (megapascals) or 400N / mm 2 Young's modulus (Newtons / square millimeter).

[0095] Therefore, the tensile modulus of the belt can be calculated and expressed as the Young's modulus of the cord 110 multiplied by the cross-sectional area of ​​the cord 110. In this example of embodiment, the belt has nine cords 110, each of which has a diameter d of 0.6 mm, resulting in a total cross-sectional area of ​​2.54 mm. 2 Therefore, the tensile modulus of the belt is approximately 1000 N. In other words, the set of cords 110 defines the tensile modulus of the belt 100 .

[0096] The cover layer 112 is a polyamide (PA), specifically polyamide 6-6 (PA66) plain weave fabric with a tubular finish and a 60 g / m 2 (g / m2) weight. Figure 9 A photograph of a cross section of an example of an embodiment of the belt 100 is shown. Figure 9 The permeability τ can be estimated qualitatively by measuring the fraction f2 of the woven fabric in the teeth relative to its thickness f1 . In this example, the permeability τ of the woven fabric into the teeth at the level of its outer surface is approximately 50%.

[0097] As mentioned above, the grammage selected in this example of embodiment is 60 g / m 2 However, the inventors believe that a lower basis weight can be used to achieve similar performance. The basis weight can be at least 20 g / m 2 , preferably at least 30 g / m 2 , and more preferably at least 40 g / m 2 .

[0098] Now refer to Figures 10 to 12 , showing the manufacturing steps of the belt 100 according to the aforementioned embodiment. Figures 10 to 12 A view of the upper half of a longitudinal cross section is shown.

[0099] Methods for making tape are well known in the art. Typically, this involves placing the tape material forming the assembly 200 around a mandrel 202, then placing the mandrel 202 and assembly 200 in a mold 204, and then pressing the mold 204 against the assembly 200, which will have the desired shape. The assembly 200 can then be cut to the desired width to obtain the tape 100.

[0100] Figure 10 1 represents the present case in which the strap material forming the assembly 200 comprises the dorsal portion 104 of the strap body 102 (in its original state), the cord 110 and the ventral portion of the strap body 102 (in its original state). Figure 10 In FIG, on the right, the assembly 200 has been positioned on the mandrel 202. Figure 10 On the left side is the sleeve 206 of the braided fabric 112 .

[0101] Then, the sleeve 206 of the braided fabric 112 is stretched approximately 20% in the direction defined by the circumference of the mandrel 202 to be placed around the mandrel 202, thereby covering the outer surface of the assembly 200, as shown. Figure 11 shown.

[0102] Figure 12 A mandrel 202 is shown with the assembly 200 and a sleeve 206 of the woven fabric 112 placed around it, the mandrel having been introduced into a mold 204 comprising at least one concave pattern on an inner wall 208 thereof.

[0103] The mold 204 is pressed against the sleeve 206 of the assembly 200 and the woven fabric 112 at a pressure of 7 bar, so that the inner wall 208 of the mold 204 having at least one concave pattern forms a corresponding convex pattern on the outer surface of the assembly 200 having the woven fabric 112. The pressure of the mold 204 also allows the woven fabric 112 to penetrate the outer surface of the tooth-shaped portion thus formed. At the same time, the mandrel 202 is heated to 170°C to vulcanize the dorsal portion 104 and the ventral portion 106 configured to form the vulcanized elastomer body 102. It should be understood that the concave pattern of the mold 204 is printed on the assembly 200 having the woven fabric 112.

[0104] Various tests were performed to characterize the belt 100 produced in this manner. In some cases, the results obtained were compared with the characteristics of a prior art belt, a round belt based on polyurethane (PU), without cords or any other form of reinforcement, having a circular cross section, a diameter of 6 mm and a tensile modulus of 250 N.

[0105] Test: Determination of the coefficient of friction of a belt of an example embodiment on a steel pulley

[0106] use Figure 12 The experimental setup shown is used to determine the coefficient of friction of a belt. In this test, a single-strand belt 100 (not welded to close itself) is placed on a pulley P. The pulley P is chosen to represent a steel roller with a circular groove. One end of the strand of the belt 100 is mounted on a mass M that generates a force F of 1.75 daN (decades of Newtons), while the other end of the belt 100 is mounted on a frame where the tension T applied to the strand of the belt 100 is measured by a suitable measuring device S (such as a force sensor). During the two minutes of the test, the pulley P rotates at a speed of 43 rpm. At the end of the two minutes, the force is then measured on the still rotating pulley.

[0107] The coefficient of friction (COF) is then determined by the following relationship:

[0108] [Formula 1]

[0109]

[0110] in:

[0111] α is the angle of the belt around the pulley, i.e., α = π / 2, expressed in radians (rad).

[0112] T is the tension measured at one end of the belt, expressed in Newtons (N),

[0113] F is the force generated by the mass at the other end of the belt, expressed in Newtons (weight).

[0114] The coefficient of friction of the strands of tape 100 tested in this manner was estimated to be 0.3.

[0115] After describing all the characteristics of the belt 100 according to an example of embodiment, in particular the tensile modulus and the coefficient of friction on steel pulleys representing the round grooved rollers of a conveyor, tests were performed to verify the performance of the belt 100 .

[0116] Result 1: Determination of the maximum transmittable torque

[0117] To determine the maximum transmittable torque of the belt 100 thus produced, a test was conducted on a test bench comprising two pulleys, one of which was a driving pulley and the other a driven pulley, simulating two rollers of a conveyor. The driving pulley rotated at a speed of 305 rpm. A resistance torque was gradually applied to the driven pulley in a gradient of 0.1 NM (Newton meter), causing the belt to slip on the pulleys. This had an impact on the defined Figure 14 The abscissa of the graph shown and described below.

[0118] When the belt 2, 100 is engaged in the groove 12, it has a certain adhesion to the bottom 14 of the groove 12, which allows the roller 10 to be driven. This adhesion resists the tangential forces on the surface of the belt 2, 100 up to a certain torque limit. If this limit is exceeded, slippage occurs and the drive is no longer possible. In practical terms, this means that the belt 2, 100 slips in the groove 12.

[0119] The total slip ρ can then be calculated from this relationship.

[0120] [Formula 2]

[0121]

[0122] in:

[0123] ρ is the total slip, expressed as a percentage (%),

[0124] R m and R rare the radius of the driving pulley and the radius of the driven pulley, respectively, each expressed in meters (m), and

[0125] ω m and ω r are the angular velocity of the driving pulley and the angular velocity of the driven pulley, respectively, each expressed in radians per second (rad / s).

[0126] Therefore, when the maximum torque is reached (i.e., when the driven pulley is stuck and its speed ω r becomes zero), the slide is 100%.

[0127] We now turn to Figure 14 , which shows a comparison of the slip according to the torque of the conventional round belt 2 (curve A) and the slip according to the torque of the belt 100 according to the example of the embodiment of the present invention (curve B).

[0128] Figure 14 Curve A shows that for a conventional round belt 2, slippage reaches 100% when the maximum torque approaches 0.7 NM. Curve B, on the other hand, shows that for the belt 100 according to the example embodiment, slippage reaches 100% when the maximum torque approaches 2.1 NM. In other words, the torque transmission capacity of the belt 100 is approximately three times that of the conventional belt 2. In practical terms, this means that the driving rollers on conveyors 1a and 1b equipped with the belt 100 according to the example embodiment can drive three times the number of driven rollers 10 as a conventional round belt 2 can.

[0129] Result 2: Durability test

[0130] The belt 100 according to the example of the embodiment was subjected to a durability test on a test bench simulating a curved conveyor. The test bench includes a drive roller and a driven roller arranged next to the drive roller, but the orientation of the longitudinal axis of the driven roller is not parallel to the longitudinal axis of the drive roller, but is more precisely arranged to be offset by 6° relative to the longitudinal axis of the drive roller. Laying the belt on the roller according to the example of the embodiment requires an 8% elongation compared to its rest length, which translates into a laying tension of 80 Newtons per strand (when its tensile modulus is 1000N). "Strand" means the portion of the belt 100 that is configured to extend between the two rollers 10 when in use. The drive roller rotates at a speed of 305rpm. These tests were carried out at room temperature.

[0131] To evaluate the belt's performance over time, the test involves repeating a certain number of on / off cycles (1s / 1s). This means the drive roller rotates for one second, then stops for one second, then starts again for one second, and so on, until 500,000 cycles are reached. The acceleration / deceleration associated with the start / stop cycles combines with the inertia of the driven roller to produce a resistive torque.

[0132] It has been observed that the belt according to the invention passes the durability test with limited signs of wear, which means that the coefficient of friction has remained stable over time.

[0133] As mentioned above, similar tests were carried out on a conventional round belt. It was observed that the round belt wore more, which made it more fragile.

[0134] This final test marks the end of the description and results associated with the fabrication example of the embodiment.

[0135] It should also be noted that other tests have been carried out on belts similar to those shown in the example of embodiment, in which only the penetration of the woven fabric into the teeth was varied in order to change the coefficient of friction. We have been able to determine that the coefficient of friction should not exceed an approximate value of 0.8, as above this value there is a risk of the belt turning over in the grooves of the rollers on curved conveyors.

[0136] Therefore, the coefficient of friction between the belt 100 and the groove 12 of the roller 10 needs to be less than or equal to 0.8.

[0137] Advantageously, the coefficient of friction of the belt 100 is non-zero and less than 0.8, and at the same time the tensile modulus of the belt 100 is between 500N and 1500N, advantageously between 800N and 1500N and preferably between 800N and 1200N.

[0138] Advantageously still, the coefficient of friction of the belt 100 with the grooves 12 of the roller 10 is between 0.3 and 0.8, combined with a tensile modulus of the belt 100 of between 500N and 1500N, advantageously between 800N and 1500N and preferably between 800N and 1200N.

[0139] The present invention also relates to Figure 1 and Figure 2 The conveyors 1a, 1b shown are similar grooved roller conveyors.

[0140] The conveyor 1a, 1b comprises a plurality of rollers 10 having grooves 12, which are connected together in pairs by the aforementioned belt 100. Advantageously, the belt 100 is mounted between the rollers 10 with a laying tension of between 60 and 100 Newtons per strand.

[0141] Figure 15 and Figure 16 The belt 100 according to the present invention is shown engaged in a groove 12 formed in the roller 10 (the groove being made, for example, of steel) and in a groove 12 belonging to the drive head 18 attached to the roller 10 (the groove being made, for example, of plastic, such as polyamide (PA), polypropylene (PP), or a composite material based on fibers embedded in a thermoplastic or thermosetting resin). In both cases, the convex teeth of the ventral portion 106 of the body 102 of the belt 100 cooperate with the groove 12, in particular with the bottom 14 of the groove 12. It should be understood that the radius of curvature of the bottom 14 of the groove 12 is substantially equal to the radius of curvature of the teeth of the ventral portion 106 of the body 102. This maximizes the contact surface between the belt 100 and the bottom 14 of the groove 12.

[0142] Figure 15 and Figure 16 Also shown are belts 100 mounted in the grooves 12 of the rollers 10 of the conveyors 1a, 1b such that the height H of each belt 100 is strictly less than the depth PR of the groove 12 housing it.

[0143] As described above, the belt 100 according to the present invention has a transmission capacity at least twice that of a conventional round belt 2. Therefore, a conveyor according to the present invention can include twice as many driven rollers 10 as a conveyor equipped with a conventional round belt 2. This means, for example, that if a conventional conveyor is designed to include a plurality of drive rollers separated from each other by at least 3 to 5 driven rollers, a conveyor according to the present invention can include a plurality of drive rollers separated from each other by at least 6 to 10 driven rollers. Of course, this number can be greater depending on the size of the conventional conveyor.

[0144] From what has been described above, it is clear that the belt according to the present invention allows for improvements in both the transmittable torque and the belt's stability. Indeed, in use, the belt's contact surface with the bottom of the roller's groove is large, thanks to the convex shape of the belt's teeth, which adapts to the concave shape of the groove. Furthermore, the combination of this convex shape of the teeth and the covering layer applied to their outer surfaces means that the belt's coefficient of friction in the groove can be set to a controlled value. By controlling the coefficient of friction and the presence of a rope that improves the belt's tensile modulus, the transmittable torque and the degree of deformation of the belt when in contact with one side of the groove can be controlled, which limits the risk of the belt flipping, particularly in curved sections of conveyors.

[0145] Another advantage is that the belt is more durable over time. In fact, since the coefficient of friction stabilizes over time, the belt wears more slowly, which increases the service life of the belt.

[0146] Another advantage is the reduced costs of producing the conveyor. Due to the improved transmittable torque achieved by the belt according to the invention, more driven rollers can be assigned to the drive rollers in the conveyor. Consequently, the number of drive rollers can be reduced, saving infrastructure and energy.

Claims

1. A conveyor belt (100) for a roller conveyor (1a, 1b) having rollers (10) with grooves (12), the grooves being made of steel or plastic, the belt include: - an elastomeric body (102) comprising a dorsal portion (104) and a ventral portion (106), the ventral portion being formed by a single tooth, the outer surface of the tooth having a convex shape configured to engage with the bottom (14) of the groove (12) of the roller (10); - a set of tension cords (110) embedded in the body (102) and located between the dorsal portion (104) and the ventral portion (106) of the body; and - a covering layer (112) arranged on the outer surface of the toothing, said covering layer defining, together with the shape of the outer surface of the toothing, a coefficient of friction with the grooves of a roller, said coefficient of friction being non-zero and less than or equal to 0.

8.

2. The belt (100) according to claim 1, in, The friction coefficient is greater than or equal to 0.

3.

3. The belt (100) according to any one of claims 1 or 2, in, The set of tension cords (110) defines a tensile modulus of the belt between 500N and 1500N, advantageously between 800N and 1500N and preferably between 800N and 1200N.

4. The belt (100) according to any one of claims 1 to 3, in, The ropes (110) of the set of ropes are made of a polyamide-based or polyester-based material.

5. The belt (100) according to any one of claims 1 to 4, in, The covering layer (112) partially embedded in the teeth is selected from a braided fabric, a woven fabric, a non-woven fabric or a fiber group.

6. The belt (100) according to claim 5, in, The cover layer (112) is made of a material selected from the group consisting of polyamide, polyester, cellulose fibers such as cotton, a mixture of cellulose fibers and polyurethane, or a combination of the above materials.

7. The belt (100) according to any one of claims 1 to 6, in, The body (102) is made of a material selected from the following: ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane, or natural rubber.

8. The belt (100) according to any one of claims 1 to 4, in, The body (102) is made of a material selected from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the covering layer (112) is a film of at least partially cross-linked thermoplastic material, the thermoplastic material comprising at least 30% polyethylene, the thermoplastic film covering the outer surface of the toothed portion.

9. The belt (100) according to claim 8, in, The membrane comprises particles and / or fibers of graphite, molybdenum disulfide and / or polytetrafluoroethylene.

10. A conveyor (1a, 1b) comprising a plurality of rollers (10) having grooves (12) made of steel or plastic, in, The rollers are connected together in pairs by means of a belt (100) according to any one of claims 1 to 9, such that the cover layer (112) of the belt is in contact with the bottom (14) of the groove (12) of the rollers.

11. The conveyor according to claim 10, in, The height (H) of the strip (100) is strictly smaller than the depth (PR) of the groove (12) receiving the strip.

12. The conveyor according to any one of claims 10 or 11, in, The grooves (12) of the roller (10) are made of a plastic material selected from polyamide, polypropylene, or a composite material based on fibers embedded in a thermoplastic or thermosetting resin.

13. The conveyor according to any one of claims 10 to 12, in, The belt (100) is mounted between the rollers (10) at a laydown tension between 60 Newtons per strand and 100 Newtons per strand.

Images