Drive belt for a roller conveyor having rollers with concave grooves and associated conveyor

Abstract

A transmission belt (100) for a roller conveyor having rollers, made of steel or plastic and having concave grooves, the belt comprising: - an elastomeric body (102) comprising a back portion (104) and a belly portion (106) formed by a single tooth, the outer surface of the elastomeric body having a convex shape configured to engage with the concave grooves of the rollers; - a set of tension cords (110) embedded in the body (102) between the back portion (104) and the belly portion (106) of the body; - a coating (112) disposed on the outer surface of the tooth, having the shape of the outer surface of the tooth and defining a coefficient of friction with the concave grooves of the rollers that is non-zero and less than or equal to 0.8.

Description

[Technical Field]

[0001] The present invention relates to a transmission belt for a roller conveyor having rollers with grooves. The present invention also relates to a grooved roller conveyor having such a belt. [Background technology]

[0002] Roller conveyors are widely used in the transportation and logistics sectors to route and sort all kinds of objects, especially packages. Generally speaking, these conveyors consist of multiple rollers driven by rotational forces driven by transmission elements. There are various types of rollers and just as many transmission elements, each with its own specific requirements. In particular, roller conveyors with rollers that usually have circular grooves are extremely common. These are shown, for example, in Figures 1 to 4.

[0003] Figures 1 and 2 show the conventional configuration of a circular groove roller conveyor, namely, the curved sections of a straight conveyor 1a as shown in Figure 1 and a conveyor 1b as shown in Figure 2.

[0004] Typically, each of the rollers 10 of conveyors 1a and 1b has a groove 12 with a circular groove bottom 14 at at least one of its longitudinal ends. A circular belt 2, i.e., a circular belt 2 having a disc-shaped cross-section, engages with 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.

[0005] During operation, the drive roller rotates an adjacent roller 10, known as a slave roller, via belt 2. This drive roller is similar to the slave roller, except that it has a motor that can be turned on by itself. The drive roller then rotates a first slave roller via the first belt 2, and the first roller itself may rotate a second slave roller via a second belt, etc.

[0006] To maximize torque transmission between the two rollers, the belt 2 must be placed on the bottom 14 of the groove 12 with the largest possible contact surface, while avoiding contact with the side surface 16 of the groove 12 as much as possible. Contact with the side surface of the groove leads to several detrimental consequences. Firstly, because there are two contact surfaces between the belt and the groove located at relatively different distances from the axis of rotation of the rollers, the belt is subjected to two very different speeds. This increases the deformation and wear of the belt. Secondly, the belt is more likely to flip over. These detrimental situations are particularly common in curved sections of a conveyor, as the curvature facilitates contact between the belt and one side of the groove.

[0007] Reference US-A1-2009 / 107809 describes a typical example of a roller conveyor.

[0008] Next, it is necessary to distinguish between different types of roller conveyors.

[0009] Figure 3 shows a first type of roller 10 made of steel, which has grooves 12 formed directly at one end of the roller 10. These grooves may, for example, be pressed into the roller. In this case, there is a region Z1 for the passage of packages that extends along the entire length of the roller 10 and thus surrounds the transmission region Z2 in which the grooves 12 and circular belts 2 are located. While this configuration allows for the widest possible passage region Z1, problems may arise if a package comes into contact with one of the belts 2. If an impact occurs between the belt 2 and the package, the belt 2 may come out of the grooves 12 of the roller 10, which may cause the conveyor to stop.

[0010] To prevent this, the diameter of the cross-section of the circular belt 2 is selected to be strictly smaller than the depth of the groove 12. For example, if the groove depth is 10 mm, the diameter of the belt cross-section is 6 mm.

[0011] However, this limits the contact surface between the belt 2 and the bottom 14 of the groove 12, and therefore the torque that can be transmitted by the belt between the two rollers.

[0012] Alternatively, as shown in Figure 4, there are rollers equipped with a drive head 18 attached to one end of the roller 10. The drive head 18, usually made of plastic, has the advantage of having a transmission region Z2 near the end of the roller 10 and the side profiles of the conveyors 1a and 1b. In this way, it is possible to separate the belt region Z2 from the region Z1 over which the conveyed package passes on the roller, and thus limit or even prevent contact between the package and the belt 2. However, for the same conveyor width, the roller in Figure 4 can drive smaller packages than the roller in Figure 3.

[0013] In reality, current circular belts have relatively poor torque transmission and insufficient service life, especially in the curved sections of conveyors where they are likely to easily flip over, and in particular, at the level of belt welding, they lead to accelerated wear or even breakage.

[0014] The documents in U.S. Patent Publication No. 2002 / 03997, U.S. Patent Publication No. 2014 / 323257, Japanese Patent Publication No. 53-37266, European Patent Publication No. 3045771, or British Patent Publication No. 697901 illustrate other types of belts that may be used in roller grooves.

[0015] Furthermore, an object of the present invention is to propose a transmission belt for a roller conveyor having grooves that do not have at least one of the above-mentioned drawbacks.

[0016] Another object of the present invention is to provide a transmission belt for a roller conveyor having rollers with grooves that provide improved performance with respect to torque that can be transmitted between two rollers.

[0017] Another object of the present invention is to propose a transmission belt for a roller conveyor having rollers with grooves, which also limits the risk of the belt turning over, particularly in curved sections of the conveyor. [Overview of the project]

[0018] Therefore, we propose a transmission belt for a roller conveyor having rollers with grooves made of steel or plastic, the belt being, - An elastomer body comprising a dorsal portion and a ventral portion formed by a single tooth, wherein the outer surface of the elastomer body has a convex shape configured to cooperate with the grooves of the roller, - A set of tension cords embedded within the main body between the back and belly portions of the main body; - A coating placed on the outer surface of the teeth, which defines the coefficient of friction with the grooves of the roller, which is 0.8 or less, not zero, based on the shape of the outer surface of the teeth.

[0019] Therefore, the present invention ensures improved torque transmission by the belt and its stability. In practice, during use, the contact surface between the belt and the bottom of the groove in the roller is wide thanks to the convex shape of the belt teeth conforming to the concave shape of the groove. In addition, the combination of this convex shape of the teeth and the coating placed on the outer surface of the teeth means that the coefficient of friction of the belt in the groove can be set to a controlled value. With a controlled coefficient of friction and the presence of a cord that improves the tensile modulus of the belt, the transmitted torque can be maintained under control. This also reduces the risk of the belt flipping over when it rides up onto the side of the groove, particularly in curved sections of the conveyor.

[0020] The belts according to the present invention may, separately from each other or combined with each other, include one or more of the following features: - The coefficient of friction is 0.3 or higher. - The tension cord set specifies the tensile modulus of the belt between 500N and 1500N, preferably between 800N and 1500N, and more preferably between 800N and 1200N. - The code of the code set is made of a polyamide-based or polyester-based material, and - the coating partially embedded in the teeth is selected from a knitted fabric, a woven fabric, a non-woven fabric, or a set of fibers. - The coating is made of a material selected from polyamide, polyester, cellulose fibers, such as cotton, a mixture of cellulose fibers and polyurethane, or a combination thereof. - The body is made of a material selected from ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane, or natural rubber. - The body is made of a material selected from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the coating is a film of at least partially cross-linked thermoplastic material containing at least 30% polyethylene, and the thermoplastic film covers the outer surface of the teeth. - The film contains particles and / or fibers of graphite, molybdenum disulfide, and / or polytetrafluoroethylene.

[0021] The present invention also relates to a conveyor comprising a plurality of rollers provided with concave grooves made of steel or plastic rollers, and the rollers are connected to each other in pairs by a belt as described above such that the coating of the belt contacts the concave grooves of the rollers.

[0022] The conveyor according to the present invention may include one or more of the following features, separately or in combination with each other: - The belt has a height strictly lower than the depth of the groove for receiving the belt. - The concave grooves of the rollers are made of a plastic material selected from polyamide, polypropylene, or a composite material based on fibers embedded in a thermoplastic or thermosetting resin, and - the belt is installed between the rollers with a laying tension between 60 N / strand and 100 N / strand.

Brief Description of the Drawings

[0023] The present invention will be preferably understood by the following description, which is given by reference to the accompanying drawings, merely as an example.

[0024] [Figure 1] This is a schematic diagram of a conventional linear roller conveyor.

[0025] [Figure 2] This is a schematic diagram of a conventional curved roller conveyor.

[0026] [Figure 3] This is a schematic diagram of the longitudinal cross-section of a grooved roller equipped with a conventional transmission belt using prior art technology.

[0027] [Figure 4] This is a schematic diagram of a longitudinal cross-section of a grooved roller with a conventional transmission belt, using prior art technology, but with a different shape.

[0028] [Figure 5] This is a schematic cross-sectional view of a transmission belt for a grooved roller conveyor according to the present invention.

[0029] [Figure 6] Figure 5 shows a schematic perspective view and a partial cross-sectional view of the belt.

[0030] [Figure 7] In particular, this is a schematic cross-sectional view of the belt according to the present invention, showing different penetration rates of the coating at the level of the outer surface of the teeth of the belt body.

[0031] [Figure 8] This is a schematic cross-sectional view of one embodiment of a belt according to the present invention, specifically defining the dimensions of the belt.

[0032] [Figure 9] Figure 8 is a cross-sectional photograph of the belt.

[0033] [Figure 10]This is a schematic diagram of a longitudinal cross-section of a mandrel around which belt material is arranged, and a braided sleeve used in the manufacture of a belt according to an example of an embodiment.

[0034] [Figure 11] Figure 10 is a schematic diagram of the longitudinal cross-section of a knitted sleeve placed on a belt material positioned on a mandrel.

[0035] [Figure 12] This is a schematic diagram of the longitudinal cross-section of the object shown in Figure 11, which has been inserted into the mold.

[0036] [Figure 13] This is a schematic diagram of the experimental setup used to measure the friction coefficient between a belt and a pulley.

[0037] [Figure 14] This graph compares the occurrence of slip as a function of transmitted torque for conventional belts known from prior art and belts in exemplary embodiments.

[0038] [Figure 15] This is a schematic diagram of the longitudinal cross-section of the belt according to the present invention, attached to a roller having the grooves shown in Figure 3.

[0039] [Figure 16] This is a schematic diagram of the longitudinal cross-section of the belt according to the present invention, attached to a roller having the grooves shown in Figure 4. [Modes for carrying out the invention]

[0040] Detailed description of the invention In the following, to explain the prior art, we will refer to the transmission belt for a roller conveyor having grooved rollers, as described above and shown in Figures 1 to 4.

[0041] Figures 5 and 6 show cross-sectional, perspective, and partial cross-sectional views of a transmission belt 100 for conveyors 1a and 1b, which have rollers 10 with grooves 12, respectively. "Groove" means any groove having a substantially concave cross-section, for example, a circular groove (i.e., a groove with a groove bottom in the shape of a circular arc, or a groove with an elliptical or egg-shaped bottom).

[0042] The belt 100 comprises an elastomer body 102 and a set of tension cords 110 and coating 112.

[0043] The elastomer body 102 includes a back portion 104.

[0044] The elastomer body 102 also includes a ventral portion 106 formed with a single tooth, the outer convex surface of which is configured to cooperate with the groove 12 of the roller conveyors 1a, 1b, 10. The outer convex surface of the tooth may be, for example, arched, elliptical, or oval, depending in particular on the shape of the concave surface forming the groove. Advantageously, the outer surface of the tooth of the ventral portion 106 forms an arc when the groove of the roller is circular.

[0045] Furthermore, this convex outer surface helps to define the coefficient of friction (COF) between the belt 100 and the groove 12 of the roller 10, where the belt 100 is installed. In practice, a higher coefficient of friction means that more torque can be transmitted. However, a higher coefficient of friction also increases the risk of the belt 100 flipping over, especially in curved sections of the conveyor. Conversely, a lower coefficient of friction means less torque is transmitted, and therefore the torque that can be transmitted from one roller to another is limited.

[0046] The control of this parameter will be discussed later.

[0047] In addition, the back portion 104 and the belly portion 106 of the main body 102 do not need to be connected by the side portion 108, but they may be connected.

[0048] The belt 100 also comprises a set of tension cords 110. The cords 110 are embedded in the body 102 between the back portion 104 and the belly portion 106 of the body 102. The cords 110 increase the tensile modulus of the belt 100. Therefore, they extend along the length of the belt and are arranged adjacent to each other across the width of the body 102. The cords 110 of the set of cords are made of a material selected from polyamide (PA) or polyester. Therefore, in the application of the problem, it is possible to transmit a large torque while maintaining the extremely limited elongation of the belt 100.

[0049] The structure of each cord 110, the number of cords 110 arranged across the width of the belt 100, and the selection of materials constituting them are modifiable and depend on the tensile modulus required for 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 that it enables higher torque transmission, in particular compared to known circular belts (generally made of polyurethane) that do not have cords for this type of conveying application.

[0050] Advantageously, the tensile modulus of the belt is selected between 500 N (Newtons) and 1500 N. More advantageously, the tensile modulus is between 800 N and 1500 N, preferably between 800 N and 1200 N.

[0051] The belt 100 also includes a coating 112 positioned on the outer surface of the teeth. This coating 112, along with the tooth shape, contributes to defining the coefficient of friction (COF) between the belt 100 and the steel roller 10 or the plastic drive head 18 of the roller 10.

[0052] The coating 112 can typically be selected from knitted fabrics, woven fabrics, nonwoven fabrics, or fiber aggregates.

[0053] In this case, the elastomer body 102 of the belt may be made of a material selected from, but is not limited to, ethylene-propylene-diene monomer (EPDM), ethylene-propylene copolymer (EPM), polybutadiene (BR), polyurethane (PU), or natural rubber.

[0054]

[0055] In this case, the coating 112 may be made of a material typically selected from polyamide, polyester, cellulose fibers, in particular cotton, a mixture of cellulose fibers and polyurethane, in particular a mixture of cotton and polyurethane, or a combination thereof.

[0056] In particular, the coating 112 may be a polyamide knit or cotton fabric mixed with polyurethane.

[0057] In this case as well, a portion of the coating 112 is embedded in the tooth.

[0058] In this case, the coefficient of friction is related to various parameters such as the type of coating 112, such as knitted or woven fabric, the properties of the material, such as polyamide, its basis weight, or its penetration rate τ into the ventral portion 106 at the level of the outer surface of the tooth. This also depends on the properties and characteristics of the elastomer.

[0059] The coefficient of friction between elastomers and steel or plastics is particularly high, usually exceeding 1.5. The above-mentioned parameters for characterizing the coating 112, depending on the selection made, make it possible to reduce the coefficient of friction (compared to the same surface without the coating 112) and thus control it. Given a number of parameters, there are many ways to define the coefficient of friction. From a practical standpoint, one may first select the type of coating 112 (knitted, woven, etc.), then the material forming it (polyamide, polyester, etc.), its basis weight (the higher the basis weight, the more the coating 112 covers the outer surface, and vice versa), and finally the penetration rate into the teeth. This penetration rate τ is defined as the ratio of the total thickness of the coating 112 embedded in the teeth of the elastomer body 102. Locally, this penetration rate τ can vary from any point on the belt 100 to another, so the average penetration rate τ over the entire belt 100 is considered. In practice, the penetration rate τ is not zero, but strictly less than 100%, and its exact value depends on the other parameters. The selection of these parameters also depends on the properties of the elastomer used.

[0060] The following are specific examples of embodiments.

[0061] Figure 7 is simply intended to illustrate this concept of the penetration rate τ of the coating 112 from the outer surface of these teeth to the teeth, where the coating 112 is considered to be a braided fabric. Thus, on the left side of Figure 7, the penetration rate τ is 0 (0%), and no part of the braided fabric 112 penetrates the body 102. In contrast, on the right side of Figure 7, the penetration rate τ is 100%, and the braided fabric 112 is completely embedded in the body 102 (right). Finally, in the center of Figure 7, various situations representing a penetration rate τ of 9, which is not zero, but strictly less than 100%.

[0062] Alternatively, coating 112 may be a film of a partially crosslinked thermoplastic material containing at least 30% polyethylene (PE), which covers the outer surface of the tooth. It is understood that the thermoplastic film does not penetrate the tooth.

[0063] In such cases, the body 102 of the belt 100 is advantageously based on ethylene alpha-olefin elastomer, particularly EPDM or EPM.

[0064] The thermoplastic film may contain polyethylene between 30% and 90%, preferably between 50% and 90%, and more preferably between 75% and 90%.

[0065] The polyethylene in the film co-crosslinks with the elastomer, such as EPDM or EPM, in the presence of peroxides or other crosslinking agents. This facilitates the adhesion of the film to the elastomer.

[0066] The thermoplastic film may consist of a blend of polyolefins containing an ethylene-containing homopolymer or copolymer. The ethylene copolymer includes ethylene / alpha-olefin copolymer, ethylene / unsaturated ester copolymer, ethylene / acrylate / acrylic acid copolymer, ethylene / methacrylic acid copolymer, and polyethylene-ethylene octene copolymer. The thermoplastic film may also be based on low-density polyethylene.

[0067] The thermoplastic film may have a thickness between 10 μm (micrometers) and 500 μm, more specifically between 50 μm and 200 μm.

[0068] Advantageously, thermoplastic films also contain particles and / or fibers of graphite, molybdenum disulfide, and / or polytetrafluoroethylene (PTFE). In particular, this affects the coefficient of friction.

[0069] The particles may have a particle size between 15 μm and 200 μm, preferably between 30 μm and 100 μm, and more specifically between 30 μm and 90 μm.

[0070] The film type described above for coating 112 is already known to those skilled in the art, and therefore its manufacture is not difficult. However, it is not used for the application under consideration here.

[0071] Example of an embodiment of the belt according to the present invention

[0072] The following shows an example of an embodiment of a method in which belt 100 may be used, with reference to Figures 5 and 8.

[0073] The elastomer body 102 is made of peroxide-cured EPDM having a hardness between 75 and 85 Shore A due to the presence of peroxides in the ethylene propylene diene monomer (EPDM) which affects the coefficient of friction. This EPDM is selected to have a viscosity of ML(1+4) and a Mooney point of 100°C. This viscosity is determined according to the ISO 289-1 standard, which specifies the test temperature (100°C), the sample preheating time before starting shearing (1 minute), and the shearing time (4 minutes).

[0074] In this embodiment, the belt 100 has the following geometric shape, as defined in Figure 8: The body 102 has a thickness, i.e., height H, of 2.3 mm and a width L of 6 mm. Each convex tooth of the body 102 has the shape of a circular arc with a diameter D of 10 mm.

[0075] The set of cords 110 embedded in the main body 102 comprises nine cords 110. Each cord 110 has a diameter d of 0.6 mm, and their centers are separated laterally by a pitch p of 0.7 mm. The center of each cord 110 is located at a distance h of 0.7 mm from the back 104 of the belt 100.

[0076] Each Code 110 is made of polyamide (PA), specifically 940 × 1 × 2 polyamide 6-6 (PA66), meaning each yarn is 940 dtex, i.e., 940 × 10 -7Each cord 110 has a linear mass density of kg / m (kilograms per meter), and each thread is first twisted individually before being twisted with the others. Each cord 110 also has a load capacity of 400 MPa (megapascals), or 400 N / mm². 2 It has a Young's modulus of (Newtons / square millimeter).

[0077] Therefore, the tensile modulus of the belt may 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 the embodiment, the belt has nine cords 110, each having a diameter d of 0.6 mm, and 2.54 mm 2 This gives the total cross-sectional area. Therefore, the tensile modulus of the belt is approximately 1000 N. In other words, the set of codes 110 defines the tensile modulus of belt 100.

[0078] Coating 112 has a tubular finish and is 60 g / m². 2 The material is a polyamide (PA) jersey knit having a basis weight of (grams / square meter), particularly polyamide 6-6 (PA66). Figure 9 shows a photograph of a cross-section of an example embodiment of belt 100. In Figure 9, the permeability τ may be qualitatively estimated by measuring the ratio f2 of the knitted fabric within the teeth to the thickness f1 of the knitted fabric. In this example, the permeability τ of the new knitted fabric into the teeth at the level of the outer surface of the knitted fabric is approximately 50%.

[0079] As described above, the basis weight selected in this example of the embodiment is 60 g / m². 2 However, the inventors believe that a lower basis weight can be used to achieve similar properties. This basis weight is at least 20 g / m². 2 Preferably, at least 30 g / m² 2 More preferably, at least 40 g / m² 2 That's fine.

[0080] Here, we refer to Figures 10 to 12, which show the steps in the manufacturing of the belt 100 according to the embodiment described above. Figures 10 to 12 show half views of the longitudinal cross-section.

[0081] Methods for manufacturing belts are well known in the prior art. Typically, this involves arranging the belt material that will form the assembly 200 around a mandrel 202, then placing the mandrel 202 together with the assembly 200 in a mold 204, and then pressing the mold 204 onto the assembly 200 to form the desired shape. The assembly 200 can then be cut to the desired width to obtain the belt 100.

[0082] Figure 10 shows the case where the belt material forming the assembly 200 comprises the (rough) back portion 104 of the belt body 102, the cord 110, and the (rough) belly portion of the belt body 102. On the right side of Figure 10, the assembly 200 is already placed on the mandrel 202. On the left side of Figure 10 is the sleeve 206 of the knitted fabric 112.

[0083] The sleeve 206 of the knitted fabric 112 is stretched by approximately 20% in the direction defined by the circumference of the mandrel 202 so that it is positioned around the mandrel 202 to cover the outer surface of the assembly 200, as shown in Figure 11.

[0084] Figure 12 shows a mandrel 202 around which an assembly 200 and a knitting sleeve 206 112 are arranged, when introduced into a mold 204 having at least one recessed pattern on its inner wall 208.

[0085] The mold 204 is pressed against the assembly 200 and the sleeve 206 of the knitted fabric 112 with a pressure of 7 bar, so that the inner wall 208 of the mold 204, which has at least one concave pattern, forms a corresponding convex pattern on the outer surface of the assembly 200 together with the knitted fabric 112. The pressure of the mold 204 also allows the knitted fabric 112 to penetrate the outer surface of the formed teeth. At the same time, the mandrel 202 is heated to 170°C to vulcanize the back portion 104 and belly portion 106 configured to form the vulcanized elastomer body 102. It is understood that the concave pattern of the mold 204 is printed onto the assembly 200 using the knitted fabric 112.

[0086] Various tests were conducted to characterize the belt 100 manufactured in this manner. In some cases, the results obtained were compared with those of a conventional belt, i.e., a circular polyurethane (PU) belt having a circular cross-section, a diameter of 6 mm, and a tensile modulus of 250 N, rather than a cord or any other form of reinforcement.

[0087] Test: Determination of the coefficient of friction of a belt in an example embodiment on a steel pulley.

[0088] The coefficient of friction of the belt was determined using the experimental apparatus shown in Figure 12. For this test, a belt 100 in the form of a single strand (not welded to close itself) is placed on a pulley P. The pulley P is selected to represent a steel roller with a circular groove. One end of the belt strand 100 is attached to a mass M that generates a force F of 1.75 daN (decanewtons), and the other end of the belt 100 is attached to a frame. The tension T exerted on the strand of the belt 100 is measured by appropriate measuring means S, such as a force sensor. The pulley P is rotated at a speed of 43 rpm for two minutes of the test. Then, at the end of these two minutes, the force is measured on the still rotating pulley.

[0089] Next, the coefficient of friction (COF) is determined by the following relationship.

number

[0090] The coefficient of friction of the strands of belt 100 tested in this manner was evaluated to be 0.3.

[0091] After identifying all the characteristics of the belt 100 according to the examples of the embodiments, particularly the tensile elastic modulus and the coefficient of friction on the steel pulley representing the circular-grooved roller of the conveyor, tests were conducted to verify the performance of the belt 100.

[0092] Result 1: Determination of the maximum transmission torque

[0093] The test for determining the maximum transmissible torque of the belt 100 manufactured in this way was conducted on a test bench comprising two pulleys simulating two rollers of the conveyor, one drive part, and one receiving part. The drive pulley rotates at 305 rpm. The resistance torque is gradually applied to the driven pulley in steps of 0.1 Nm (Newton meter) so that the belt slides on the pulley. This pair defines the abscissa of the graph shown in FIG. 14 and described below.

[0094] When the belt 2,100 engages with the groove 12, the belt has a certain adhesion force with the bottom 14 of the groove 12 and can drive the roller 10. This adhesion will withstand a certain torque limit for the tangential force on the surface of the belt 2,100. If this limit is exceeded, slip occurs and it will not be driven any further. Practically, this means that the belt 2,100 slips within the groove 12.

[0095] Next, the overall slip ρ is calculated according to the relationship

Equation

[0096] Therefore, when the maximum torque is reached, that is, when the driven pulley is blocked, its speed ω r When it becomes 0, the slip becomes 100%.

[0097] Here, we refer to Figure 14, which shows a comparison of the occurrence of slip as a function of torque for a conventional circular belt 2 (curve A) and a belt 100 (curve B) according to an example of an embodiment of the present invention.

[0098] Curve A in Figure 14 shows that, in the case of the conventional circular belt 2, slip is 100% at a maximum torque close to 0.7 Nm. On the other hand, curve B shows that, in the case of belt 100 according to the embodiment, slip is 100% at a maximum torque close to 2.1 Nm. In other words, belt 100 has approximately three times the torque transmission capacity of the conventional belt 2. In practice, this means that the drive rollers on conveyors 1a and 1b equipped with belt 100 in the embodiment can drive three times the number of slave rollers 10 compared to the conventional circular belt 2.

[0099] Result 2: Durability Test

[0100] The durability test of the belt 100 according to the embodiment was performed on a test stand simulating a curved conveyor. This test stand comprises a drive roller and a slave roller positioned next to the drive roller, but its longitudinal axis is not oriented parallel to the longitudinal axis of the drive roller, but more precisely, it is positioned at an angle of 6° with respect to the longitudinal axis of the drive roller. Laying the belt on the roller according to the embodiment requires an elongation of 8% compared to its resting length, which translates to a laying tension of 80 N / strand (for a tensile modulus of 1000 N). "Strand" refers to the portion of the belt 100 configured to extend between the two rollers 10 when in use. The drive roller rotates at 305 rpm. The test was performed at room temperature.

[0101] To evaluate the belt's behavior over time, the test consists of repeating a certain number of on / off cycles of 1 s / 1 s (seconds). This means the drive roller rotates for 1 second, then stops for 1 second, then starts again for 1 second, and continues until 500,000 cycles are reached. The acceleration / deceleration associated with the start / stop cycles, combined with the slave roller's inertia, generates resistive torque.

[0102] The belt according to the present invention has been observed to pass this durability test with limited signs of wear. This means that the coefficient of friction remains stable over time.

[0103] Similar tests were conducted with conventional circular belts, as described above. It was observed that the circular belts became more brittle and more prone to wear.

[0104] This final test concludes the description and results related to the manufacturing examples of the embodiments.

[0105] It should also be noted that, in order to change the coefficient of friction, other tests were conducted on belts similar to those shown in the embodiment, by only changing the rate at which the knitted fabric penetrated the teeth. It was determined that the coefficient of friction should not exceed an approximate value of 0.8, because exceeding this value poses a risk of the belt turning inside out in the grooves of the rollers on a curved conveyor.

[0106] Therefore, the coefficient of friction between the belt 100 and the groove 12 of the roller 10 must be 0.8 or less.

[0107] Advantageously, the coefficient of friction of belt 100 is less than 0.8, not zero, and at the same time, the tensile modulus of belt 100 is between 500N and 1500N, advantageously between 800N and 1500N, preferably between 800N and 1200N.

[0108] More advantageously, the coefficient of friction between the belt 100 and the groove 12 of the roller 10 is between 0.3 and 0.8, which is combined with a tensile modulus of elasticity of the belt 100 between 500N and 1500N, preferably between 800N and 1500N, and more preferably between 800N and 1200N.

[0109] The present invention also relates to a grooved roller conveyor similar to the conveyors 1a and 1b shown in Figures 1 and 2.

[0110] The conveyors 1a and 1b are equipped with a plurality of rollers 10 having grooves 12 that are connected to each other in pairs by a belt 100 as described above. Advantageously, the belt 100 is laid between the rollers 10 with a laying tension of 60 N / strand to 100 N / strand.

[0111] Figures 15 and 16 show a belt 100 according to the present invention that engages with grooves 12 formed in a roller 10, for example, made of steel, and grooves 12 belonging to a drive head 18 attached to the roller 10, which are made of plastic, such as polyamide (PA), polypropylene (PP), or composite material based on fibers embedded in thermoplastic or thermosetting resin. In both cases, the convex teeth of the belly portion 106 of the body 102 of the belt 100 cooperate with the grooves 12, in particular the bottom 14 of the grooves 12. It is understood that the radius of curvature of the bottom 14 of the grooves 12 is substantially equal to the radius of curvature of the teeth of the belly portion 106 of the body 102. This maximizes the contact surface between the belt 100 and the bottom 14 of the grooves 12.

[0112] Figures 15 and 16 also show that the belts 100 are mounted in the grooves 12 of the rollers 10 of the conveyors 1a and 1b such that each belt 100 has a height H that is strictly lower than the depth PR of the groove 12 that receives each belt 100.

[0113] As described above, the transmission capacity of the belt 100 according to the present invention is at least twice that of a conventional circular belt 2. Therefore, the conveyor according to the present invention may have twice the number of slave rollers 10 as a conveyor with a conventional circular belt 2. This is because, for example, a conventional conveyor has multiple drive rollers separated from each other by at least 3 to 5 slave rollers. If sized to include rollers, the conveyor according to the present invention can have a plurality of drive rollers separated from each other by at least 6 to 10 slave rollers. Naturally, this can be even larger if a conventional conveyor is of such size.

[0114] In light of the above, it is clear that the belt according to the present invention enables improvements in the torque that can be transmitted by the belt and its stability. In fact, during use, the contact surface between the belt and the bottom of the groove of the roller is wide thanks to the convex shape of the belt teeth that conforms to the concave shape of the groove. In addition, the combination of this convex shape of the teeth and the coating placed on the outer surface of the teeth means that the coefficient of friction of the belt in the groove can be set to a controlled value. The controlled coefficient of friction and the presence of a cord that improves the tensile modulus of the belt allow for control of the transmitted torque and the level of deformation of the belt when in contact with one side of the groove, which limits the risk of the belt turning over, especially in curved sections of the conveyor.

[0115] Another advantage is that the belt is durable over time. In fact, thanks to a stable coefficient of friction over time, the belt does not wear out rapidly, which extends its service life.

[0116] Another advantage is the reduction in conveyor manufacturing costs. In fact, thanks to the improved torque transmittable by the belt according to the present invention, many slave rollers can be subordinate to the drive rollers in the conveyor. As a result, the number of drive rollers can be reduced, saving infrastructure and energy.

[0117] The present invention includes the matters described in the following sections.

[0118] Item 1. A transmission belt (100) for a roller conveyor (1a, 1b) having rollers (10) with grooves (12) made of steel or plastic, wherein the belt is - An elastomer body (102) comprising a dorsal portion (104) and a ventral portion (106) formed by a single tooth, wherein the outer surface of the elastomer body (102) has 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 main body (102) between the back portion (104) and the belly portion (106) of the main body, - A coating (112) disposed on the outer surface of the tooth, wherein the shape of the outer surface of the tooth defines the coefficient of friction with the groove of the roller, which is 0.8 or less, not zero. A transmission belt (100) equipped with [a specific feature].

[0119] Item 2. The belt (100) described in Item 1, wherein the coefficient of friction is 0.3 or greater.

[0120] Item 3. The belt (100) according to either item 1 or 2, wherein the set of tension cords (110) specifies a tensile modulus of the belt between 500N and 1500N, preferably between 800N and 1500N, and more preferably between 800N and 1200N.

[0121] Item 4. The belt (100) according to any one of items 1 to 3, wherein the code (110) of the set of codes is made of a polyamide or polyester material.

[0122] Item 5. The belt (100) according to any one of items 1 to 4, wherein the coating (112) partially embedded in the teeth is selected from a set of knitted fabrics, woven fabrics, nonwoven fabrics, or fibers.

[0123] Item 6. The belt (100) according to Item 5, wherein the coating (112) is made of a material selected from polyamide, polyester, cellulose fibers, for example, cotton, a mixture of cellulose fibers and polyurethane, or a combination thereof.

[0124] Item 7. The belt (100) according to any one of items 1 to 6, wherein the body (102) is made of a material selected from ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane, or natural rubber.

[0125] Item 8. The belt (100) according to any one of items 1 to 4, wherein the body (102) is made from a material selected from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the coating (112) is a film of at least partially crosslinked thermoplastic material containing at least 30% polyethylene, the thermoplastic film covering the outer surface of the teeth.

[0126] Item 9. The belt (100) according to Item 8, wherein the film comprises particles and / or fibers of graphite, molybdenum disulfide, and / or polytetrafluoroethylene.

[0127] Item 10. A conveyor (1a, 1b) comprising a plurality of rollers (10) having grooves (12) made of steel or plastic, wherein the rollers are connected in pairs by a belt (100) as described in any one of items 1 to 9, so that the coating (112) of the belt is in contact with the bottom (14) of the grooves (12) of the rollers.

[0128] Item 11. The conveyor according to item 10, wherein the belt (100) is at a height (H) that is strictly lower than the depth (PR) of the groove (12) that receives the belt (100).

[0129] Item 12. The conveyor according to either item 10 or 11, wherein the groove (12) of the roller (10) is made of a plastic material selected from polyamide, polypropylene, or composite materials based on fibers embedded in thermoplastic or thermosetting resin.

[0130] Item 13. The conveyor according to any one of items 10 to 12, wherein the belt (100) is installed between the rollers (10) with a laying tension of 60 N / strand to 100 N / strand.

Claims

1. A transmission belt (100) for a roller conveyor (1a, 1b) having rollers (10) with grooves (12) made of steel or plastic, wherein the belt is - An elastomer body (102) comprising a dorsal portion (104) and a ventral portion (106) formed by a single tooth, wherein the outer surface of the elastomer body (102) has a convex shape configured to engage with the bottom portion (14) of the groove (12) of the roller (10), - A set of tension cords (110) embedded in the main body (102) between the back portion (104) and the belly portion (106) of the main body, - A coating (112) disposed on the outer surface of the tooth, wherein the shape of the outer surface of the tooth defines the coefficient of friction with the groove of the roller, which is 0.8 or less, not zero. A transmission belt (100) equipped with [a specific feature].

2. The belt (100) according to claim 1, wherein the coefficient of friction is 0.3 or more.

3. The belt (100) according to claim 1 or 2, wherein the set of tension cords (110) defines the tensile modulus of the belt between 500 N and 1500 N, preferably between 800 N and 1500 N.

4. The belt (100) according to claim 1, wherein the cord (110) of the set of cords is made of a polyamide or polyester material.

5. The belt (100) according to claim 1, wherein the coating (112) partially embedded in the teeth is selected from a set of knitted fabrics, woven fabrics, nonwoven fabrics, or fibers.

6. The belt (100) according to claim 5, wherein the coating (112) is made of a material selected from polyamide, polyester, cellulose fiber, a mixture of cellulose fiber and polyurethane, or a combination thereof.

7. The belt (100) according to claim 1, wherein the main body (102) is made of a material selected from ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane, or natural rubber.

8. The belt (100) according to claim 1, wherein the main body (102) is made from a material selected from ethylene-propylene-diene monomer or ethylene-propylene copolymer, the coating (112) is a film of at least partially crosslinked thermoplastic material containing at least 30% polyethylene, and the thermoplastic film covers the outer surface of the teeth.

9. The belt (100) according to claim 8, wherein the film 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, wherein the rollers are connected to each other in pairs by a belt (100) as described in claim 1, so that the coating (112) of the belt contacts the bottom (14) of the grooves (12) of the rollers.

11. The conveyor according to claim 10, wherein the belt (100) is at a height (H) that is strictly lower than the depth (PR) of the groove (12) that receives the belt (100).

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

13. The conveyor according to claim 10, wherein the belt (100) is installed between the rollers (10) with a laying tension of 60 N / strand to 100 N / strand.

14. The belt (100) according to claim 3, wherein the tensile modulus of the belt is between 800 N and 1200 N.

15. The belt (100) according to claim 6, wherein the cellulose fiber is cotton.

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