DRIVE BELT FOR CONCAVE GROOVE ROLLER CONVEYOR AND ASSOCIATED CONVEYOR

Abstract

A conveyor belt (100) for a roller conveyor having concave grooves made of steel or plastic, said belt comprising: - a body (102) made of elastomer comprising a dorsal portion (104) and a ventral portion (106) formed of a single tooth, the external surface of which has a convex shape configured to cooperate with a concave groove of a roller; - a set of traction cables (110) embedded in the body (102) between the dorsal portion (104) and the ventral portion (106) of said body; and - a coating (112) arranged on the external surface of the teeth defining, together with the shape of the external surface of the teeth, a non-zero coefficient of friction less than or equal to 0.8 with the concave groove of a roller. Figure for the abbreviation: Figure 5

Description

Title of the invention: TRANSMISSION BELT FOR CONCAVE-GROOVED ROLLER CONVEYOR AND ASSOCIATED CONVEYOR Technical field of the invention

[0001] The present invention relates to a transmission belt for a concave groove roller conveyor. The invention also relates to a concave groove roller conveyor provided with such belts. Technological background

[0002] Roller conveyors are widely used in the logistics and goods flow sector for transporting and sorting objects of all kinds, and in particular parcels. Generally speaking, these conveyors comprise a plurality of rollers driven in rotation by a motor element by means of transmission elements. There are different types of rollers and just as many transmission elements, each meeting specific criteria. In particular, roller conveyors with so-called concave grooves, most often round, are very widespread. They are shown for example in Figures 1 to 4.

[0003] Figures 1 and 2 show conventional configurations of round groove roller conveyors, i.e., a straight conveyor 1a as shown in [Fig.l] and a curved portion of a conveyor 1b as shown in [Fig.2].

[0004] Conventionally, each of the rollers 10 of the conveyor 1a, 1b comprises at least, at one of its longitudinal ends, grooves 12 whose groove bottom 14 is round. Belts 2 called round, that is to say whose section forms a disc, are engaged in these grooves 12 to allow the rollers 10 to be driven. These belts, typically made of polyurethane, have the advantage of being inexpensive and easy to mount in the grooves.

[0005] In operation, a motorized roller drives the adjacent rollers 10, called slave rollers, in rotation by means of the belts 2. This motorized roller is similar to the slave rollers except that it is equipped with a motor allowing it to rotate on itself. A motorized roller then drives a first slave roller in rotation, by means of a first belt 2, a first roller which can itself drive a second slave roller in rotation by means of a second belt, etc.

[0006] To maximize the transmission of torque between two rollers, the belt 2 must bear on the bottom 14 of the groove 12 with the largest possible contact surface, while avoiding as much as possible contact with the side 16 of the groove 12. Indeed, the existence of contact with the side of the groove implies several harmful consequences. Firstly, the belt is then subjected to two speeds that are too different because there are then two contact surfaces between the belt and the groove which are located at relatively different distances from the axis of rotation of the roller. Such a situation accentuates the deformation of the belt and therefore its wear. Secondly, it facilitates the reversal of the belt. These harmful situations are particularly encountered in the curved part of a conveyor, the curvature in fact favoring the contact of the belt with one side of the groove.

[0007] It is then appropriate to distinguish between different types of roller conveyors.

[0008] [Fig. 3] shows a first type of roller 10, made of steel, which has grooves 12 formed directly in the roller 10 at one of its ends. These grooves can, for example, be stamped into the roller. In such a case, there is a zone ZI for the passage of the parcels which extends over the entire length of the roller 10, thus including a transmission zone Z2 where the grooves 12 and the round belts 2 are located. Although this configuration makes it possible to have the widest possible passage zone ZI, this can prove problematic if a parcel comes into contact with one of the belts 2. Indeed, in the event of an impact between the belt 2 and the parcel, the belt 2 can disengage from the groove 12 of the roller 10, which is likely to cause the conveyor to stop.

[0009] Also, to prevent this from happening, the diameter of the section of the round belt 2 is chosen to be strictly less than the depth of the groove 12. For example, for a groove 10 mm (millimeter) deep, the diameter of the section of the belt is 6 mm.

[0010] Nevertheless, this limits the contact surface between the belt 2 and the bottom 14 of the groove 12, and therefore the torque transmissible by the belt between two rollers.

[0011] Alternatively, there are rollers with a drive head 18 mounted at one end of the roller 10, as illustrated in [Fig. 4]. The drive head 18, typically made of plastic material, offers the advantage of having a transmission zone Z2, closer to the end of the roller 10 and the lateral profile of the conveyor 1a, 1b. It is thus possible to separate the zone Z2 of the belts and the zone Z1 for the passage of the packages to be transported on the rollers, thus limiting, or even preventing, the packages from coming into contact with the belts 2. However, for an identical conveyor width, the rollers of [Fig. 4] will be able to drive smaller packages than the rollers of [Fig. 3].

[0012] In practice, it is found that current round belts offer relatively low torque transmission and service life, particularly in the curved parts of a conveyor where they are likely to turn over more easily, resulting in accelerated wear or even breakage, particularly at the level of belt welding.

[0013] Also, an objective of the invention is to propose a transmission belt for a roller conveyor with concave grooves which does not have at least one of the aforementioned drawbacks.

[0014] Another objective of the invention is to propose a transmission belt for a roller conveyor with concave grooves offering improved performance on the torque transmissible between two rollers.

[0015] Another objective of the invention is to propose a transmission belt for a roller conveyor with concave grooves which also limits the risks of the belt turning over, particularly in a curved part of a conveyor. Summary of the invention

[0016] There is therefore proposed a transmission belt for a roller conveyor having concave grooves made of steel or plastic, the belt comprising: - an elastomer-based body comprising a dorsal portion and a ventral portion formed of a single toothing, an external surface of which has a convex shape which is configured to cooperate with a concave groove of a roller; - a set of traction cables embedded in the body between the dorsal portion and the ventral portion of the body; and - a coating arranged at the level of the external surface of the teeth defining, with the shape of the external surface of the teeth, a coefficient of friction which is not zero and less than or equal to 0.8 with the concave groove of a roller.

[0017] Thus, thanks to the invention, an improvement in the torque transmissible by the belt and its stability are ensured. Indeed, in use, the contact surface between the belt and the bottom of the groove of the roller is high thanks to the convex shape of the teeth of the belt which adapts to the concave shape of the groove. In addition, the combination of this convex shape of the teeth with the coating arranged at the external surface of the teeth makes it possible to define the coefficient of friction of the belt in the groove at a controlled value. With a controlled coefficient of friction and the presence of cords improving the traction modulus of the belt, the transmissible torque can be controlled. Furthermore, this limits the risks of the belt turning over when it climbs up the side of the groove, in particular in a curved part of a conveyor.

[0018] The belt according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - the coefficient of friction is greater than or equal to 0.3; - the traction cable assembly defines a traction modulus of the belt of between 500 N and 1500 N, advantageously of between 800 N and 1500 N, and preferably of between 800 N and 1200 N; - the cables of the cable assembly are made of a polyamide or polyester-based material; - the coating, partially embedded in the teeth, is chosen from a knit, a fabric, a non-woven fabric or a set of fibers; - the coating is made of a material chosen from polyamide, polyester, cellulose fibers, for example cotton, a mixture of cellulose fibers and polyurethane or a combination thereof; - the body is made of a material chosen from ethylene-propylene-diene monomer, ethylene-propylene copolymer, polybutadiene, polyurethane or natural rubber; - the body is made of a material chosen from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the coating is a film of at least partly crosslinked thermoplastic material, comprising at least 30% polyethylene, the thermoplastic film covering the external surface of the teeth; - the film comprises particles and / or fibers of graphite, molybdenum disulfide and / or polytetrafluoroethylene.

[0019] The invention also relates to a conveyor comprising a plurality of rollers with concave grooves made of steel or plastic, in which the rollers are connected to each other two by two by a belt as described above, so that the coating of the belt is in contact with the concave grooves of the rollers.

[0020] The conveyor, according to the invention, may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - the belt has a height strictly less than the depth of the groove receiving it; - the concave grooves of the rollers are made of a plastic material chosen from a polyamide, a polypropylene or a composite material based on fibers embedded in a thermoplastic or thermosetting resin; - the belt is installed between the rollers with a laying tension between 60 N / strand and 100 N / strand. Brief description of the figures

[0021] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0022] [Fig.l] represents a schematic view of a straight roller conveyor according to the prior art,

[0023] [Fig. 2] represents a schematic view of a curved roller conveyor according to the prior art,

[0024] [Fig. 3] represents a schematic view in longitudinal section of a concave grooved roller with a conventional transmission belt according to the prior art,

[0025] [Fig. 4] represents a schematic view in longitudinal section of another form of concave grooved roller with a conventional transmission belt according to the prior art,

[0026] [Fig. 5] represents a schematic cross-sectional view of the transmission belt for a concave groove roller conveyor according to the invention,

[0027] [Fig.6] represents a schematic perspective and partial sectional view of the belt of [Fig.5],

[0028] [Fig. 7] represents a schematic cross-sectional view of the belt according to the invention, illustrating in particular different penetration rates of the coating at the external surface of the teeth of the belt body,

[0029] [Fig. 8] represents a schematic cross-sectional view of an embodiment of the belt according to the invention, defining in particular the dimensions of the belt,

[0030] [Fig.9] represents a photographic cross-sectional view of the belt of [Fig.8],

[0031] [Fig. 10] represents a schematic view in longitudinal section of a mandrel, around which belt materials are placed, and of a knitted sleeve as used during the manufacture of a belt according to the exemplary embodiment,

[0032] [Fig. 11] represents a schematic view in longitudinal section of the knitted sleeve placed on the belt materials, themselves arranged on the mandrel of [Fig. 10],

[0033] [Fig. 12] represents a schematic view in longitudinal section of the object of [Fig. 1 1] introduced into a mold,

[0034] [Fig. 13] is a schematic view of an experimental setup used to measure the coefficient of friction of a belt with a pulley,

[0035] [Fig. 14] is a graph comparing the evolution of the slip as a function of the transmitted torque for a conventional belt known from the prior art and the belt of the exemplary embodiment,

[0036] [Fig. 15] represents a schematic view in longitudinal section of the belt according to the invention, mounted on a roller with concave grooves as shown in [Fig. 3], and

[0037] [Fig. 16] represents a schematic view in longitudinal section of the belt according to the invention, mounted on a roller with concave grooves as shown in [Fig. 4], Detailed description of the invention

[0038] In the following, reference is made to a transmission belt for a concave groove roller conveyor, such as those described above to illustrate the state of the art and shown in Figures 1 to 4.

[0039] Now, we are interested in [Fig.5] and [Fig.6] which respectively show a sectional view and a perspective and partial sectional view of a transmission belt 100 for conveyor 1a, 1b with rollers 10 with concave grooves 12. The term "concave grooves" means any groove having a generally concave section, for example a round groove (i.e. having a groove base in the shape of an arc of a circle, or a groove having an elliptical or even ovoid base).

[0040] The belt 100 comprises an elastomer-based body 102, a set of traction cords 110 and a covering 112.

[0041] The elastomer-based body 102 comprises a dorsal portion 104.

[0042] The elastomer-based body 102 also comprises a ventral portion 106, formed of a single toothing of which an external, convex surface is configured to cooperate with a concave groove 12 of the roller conveyor 1a, 1b 10. The external, convex surface of the toothing may for example have the shape of an arc of a circle, an ellipse or an ovoid, in particular depending on the shape of the concavity forming the groove. Advantageously, the external surface of the toothing of the ventral portion 106 forms an arc of a circle, when the groove of the roller is round.

[0043] Furthermore, this convex external surface contributes to defining the coefficient of friction (COF) between the belt 100 and the groove 12 of the roller 10 in which the belt 100 is intended to be installed. In practice, the higher this coefficient of friction, the greater the torque that can be transmitted. However, the higher this coefficient of friction, the greater the risk of the belt 100 turning over, particularly in a curved part of a conveyor. On the contrary, the lower this coefficient of friction, the less torque that can be transmitted, thus limiting the torque that can be transmitted from one roller to another.

[0044] Control of this parameter will be discussed later.

[0045] Furthermore, the dorsal portion 104 and the ventral portion 106 of the body 102 may be connected to each other by lateral portions 108, but not necessarily.

[0046] The belt 100 also comprises a set of traction cables 110. The cables 110 are embedded in the body 102 between the dorsal portion 104 and the ventral portion 106 of the body 102. The cables 110 make it possible to increase the modulus of traction of the belt 100. They therefore extend along the length of the belt and are arranged next to each other across the width of the body 102. A cord 110 of the set of cords may in particular be made of a material chosen from polyamide (PA) or polyester. They therefore make it possible, for the application in question, to allow greater torque transmission while maintaining a very limited elongation of the belt 100.

[0047] The composition of each cord 110, the number of cords 110 arranged in the width of the belt 100 and the choice of the material constituting them is variable and depends on the desired tensile modulus for the belt 100 to ensure torque transmission while limiting the elongation of the belt 100. The presence of such cords 110 has the general effect of allowing higher torque transmission, in particular compared to known round belts (generally made of polyurethane) which do not have cords for this type of conveying application.

[0048] Advantageously, the traction modulus of the belt is chosen between 500 N (Newton) and 1500 N. Advantageously again, the traction modulus is between 800 N and 1500 N, and preferably between 800 N and 1200 N.

[0049] The belt 100 also comprises a coating 112 arranged at the external surface of the teeth. This coating 112 contributes, with the shape of the teeth, 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.

[0050] The coating 112 may typically be chosen from a knit, a fabric, a non-woven fabric or even a set of fibers.

[0051] In this case, the elastomer-based body 102 of the belt may be made of a material chosen in a non-limiting manner from ethylene-propylene-diene monomer (EPDM), ethylene-propylene copolymer (EPM), polybutadiene (BR), polyurethane (PU) or natural rubber.

[0052]

[0053] In this case, the coating 112 may be made of a material typically chosen from a polyamide, a polyester, cellulosic fibers, in particular cotton, a mixture of cellulosic fibers and polyurethane, in particular a mixture of cotton and polyurethane or a combination thereof.

[0054] In particular, the coating 112 may be a polyamide knit, a cotton fabric mixed with polyurethane.

[0055] In such a case also, a part of the coating 112 is embedded in the toothing.

[0056] In this case, the coefficient of friction is linked to different parameters, such as the type of coating 112, for example knit or fabric, the nature of its material, for example polyamide, its weight or even its penetration rate r in the ventral portion 106 at the level of the external surface of the teeth. This also depends also on the nature of the elastomer and its properties.

[0057] Indeed, the coefficient of friction of an elastomer with a steel or a plastic is particularly high, typically greater than 1.5. The parameters mentioned above to characterize the coating 112 make it possible, depending on the choices made, to reduce the coefficient of friction (compared to this same surface without coating 112) and, therefore, to control it. Given the number of parameters, there are multiple ways of defining the coefficient of friction. From a practical point of view, one can first choose the type of coating 112 (knit, fabric, etc.) then the material composing it (polyamide, polyester, etc.), its weight (the higher the weight, the more the coating 112 covers the external surface and vice versa) and finally its rate of penetration into the teeth. This rate of penetration r is defined as being the fraction of the total thickness of the coating 112 which is embedded in the teeth of the elastomer-based body 102.Locally, this penetration rate r can vary from one place to another on the belt 100, so we consider an average penetration rate r over the entire belt 100. In practice, the penetration rate r will be non-zero and strictly less than 100%, its exact value depending on the other parameters. The choice of these parameters will also depend on the nature of the elastomer used.

[0058] A concrete example of implementation will be given below.

[0059] [Fig.7] only aims to illustrate this notion of penetration rate r of the re garment 112 into the toothing from the external surface of this toothing, the covering 112 considered here being a knit. Thus, on the left of this [Fig.7], with a penetration rate r at new zero (0%), no fraction of the knit 112 penetrates into the body 102. On the contrary, on the right of this [Fig.7], with a penetration rate r at new of 100%, the knit 112 is entirely embedded in the body 102 (on the right). Finally, in the middle of this [Fig.7], various situations representative of a penetration rate r at new non-zero and strictly less than 100% have been shown.

[0060] Alternatively, the coating 112 may be a film of partially crosslinked thermoplastic material, comprising at least 30% polyethylene (PE), this film covering the external surface of the toothing. It is understood that the thermoplastic film does not penetrate into the toothing.

[0061] In such a case, the body 102 of the belt 100 is advantageously based on ethylene alpha olefin elastomer, in particular an EPDM or an EPM.

[0062] The thermoplastic film may comprise between 30% and 90% polyethylene, advantageously between 50% and 90% polyethylene, and preferably between 75% and 90% polyethylene.

[0063] The polyethylene of the film co-crosslinks with the elastomer, for example EPDM or EPM, due to the presence of peroxide or another crosslinking agent. This promotes the adhesion of the film to the elastomer.

[0064] The thermoplastic film may consist, in a non-limiting manner, of a mixture of polyolefins containing a homo or a copolymer comprising ethylene. Ethylene copolymers include, in particular, ethylene / alpha-olefin copolymers, ethylene / unsaturated ester copolymers, ethylene / acrylate / acrylic acid copolymers, ethylene / methacrylic acid copolymers and polyethylene-ethyleneoctene copolymers. The thermoplastic film may also be based on low-density polyethylene.

[0065] The thermoplastic film may have a thickness of between 10 μm (micrometer) and 500 μm, and more particularly between 50 μm and 200 μm.

[0066] Advantageously, the thermoplastic film also comprises particles and / or fibers of graphite, molybdenum disulfide and / or polytetrafluoroethylene (PTFE). This makes it possible, among other things, to influence the coefficient of friction.

[0067] The particles may have a particle size of between 15 pm and 200 pm, advantageously between 30 pm and 100 pm and more particularly between 30 pm and 90 pm.

[0068] The type of film described above for the coating 112 is already known per se to those skilled in the art and its manufacture therefore poses no difficulty. However, it is not used for the application considered here.

[0069] Example of embodiment of a belt according to the invention

[0070] In the following, reference is made to [Fig.5] and [Fig.8] which show an example of embodiment of the belt 100.

[0071] The elastomer-based body 102 is made of peroxide-vulcanized ethylene-propylene-diene monomer (EPDM) with a hardness of between 75 and 85 Shore A due to the presence of peroxide in the EPDM, which has an influence on the coefficient of friction. This EPDM is chosen with a viscosity of 100 Mooney points, ML (1+4) at 100°C. This viscosity is determined according to the ISO 289-1 standard, which specifies in particular the test temperature (100°C), the duration of preheating of the sample before starting shearing (1 min) and the shearing duration (4 min).

[0072] In this exemplary embodiment, the belt 100 has a geometry defined as follows and illustrated by [Fig.8]. The body 102 has a thickness, or height, H of 2.3 mm and a width L of 6 mm. The single convex toothing of the body 102 has the shape of an arc of a circle whose diameter D is 10 mm.

[0073] The set of cords 110 embedded in the body 102 comprises nine cords 110. The cords 110 have 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 furthermore located at a distance h of 0.7 mm from the dorsal portion 104 of the belt 100.

[0074] Each cord 110 is made of polyamide (PA), and in particular polyamide 6-6 (PA66) 940x1x2, that is to say that each thread has a count of 940 dtex (decitex), or 940x107 kg / m (kilogram per meter), and that each thread is first twisted individually before being twisted with the other. Each 110 cable also has a Young's modulus of 400 MPa (MegaPascal), or 400 N / mm2 (Newton per square millimeter).

[0075] The tensile modulus of the belt can thus be calculated and is expressed as the multiplication of the Young's modulus of the cord 110 with the cross-sectional area of ​​the cord 110. In the exemplary embodiment, the belt has nine cords 110, the diameter d of each cord 110 of which is 0.6 mm, i.e. a total cross-sectional area of ​​2.54 mm2. Thus, 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.

[0076] The coating 112 is a jersey-type knit made of polyamide (PA), and in particular polyamide 6-6 (PA66), with a tubular finish and a weight of 60 g / m2 (grams per square meter). [Fig. 9] shows a photograph of a section of the exemplary embodiment of the belt 100. In this [Fig. 9], the penetration rate r can be qualitatively estimated by measuring the fraction f2 of the knit found in the teeth relative to the thickness fl of the knit. In the present example, the penetration rate r when new of the knit in the teeth at its external surface is of the order of 50%.

[0077] With reference to what has been previously mentioned, the grammage chosen in this exemplary embodiment is 60 g / m2. However, the inventors believe that a lower grammage can be used to achieve similar properties. This grammage can be at least 20 g / m2, preferably at least 30 g / m2, and more preferably at least 40 g / m2.

[0078] Reference is now made to Figures 10 to 12 illustrating steps of manufacturing a belt 100 according to the aforementioned embodiment. Figures 10 to 12 show half-views in longitudinal section.

[0079] The method of manufacturing a belt is well known in the prior art. Conventionally, it consists of placing belt materials forming an assembly 200 around a mandrel 202 and then placing this mandrel 202 with the assembly 200 in a mold 204, this mold 204 then being pressed against the assembly 200 which takes the desired shape. The assembly 200 can then be cut to a desired width to obtain a belt 100.

[0080] [Fig. 10] represents the present case, where the belt materials that form the assembly 200 comprise the dorsal portion 104 (in the raw state) of the body 102 of the belt, the cords 110 and the ventral portion (in the raw state) of the body 102 of the belt. In [Fig. 10], on the right, the assembly 200 is already placed on the mandrel 202. On the left of this same [Fig. 10] is represented a sleeve 206 of knit 112.

[0081] The sleeve 206 of knit 112 is then elongated, by approximately 20%, in the direction defined by the circumference of the mandrel 202, to be placed around the mandrel 202 of so as to cover the external surface of the assembly 200, as shown in [Fig. 11].

[0082] [Fig. 12] shows the mandrel 202, with the assembly 200 and the sleeve 206 of knit 112 placed around it, once introduced into a mold 204 having on its internal wall 208 at least one concave pattern.

[0083] The mold 204 is pressed, with a pressure of 7 bars, against the assembly 200 and the sleeve 206 of knit 112 so that the internal wall 208 of the mold 204 with at least one concave pattern forms a corresponding convex pattern on the external surface of the assembly 200 with the knit 112. The pressure of the mold 204 further allows the penetration of the knit 112 at the external surface of the toothing thus formed. At the same time, the mandrel 202 is heated to 170°C to ensure vulcanization of the dorsal 104 and ventral 106 portions intended to form the body 102 of vulcanized elastomer. It is understood that the concave pattern of the mold 204 is printed on the assembly 200 with the knit 112.

[0084] In the following, various tests were carried out in order to characterize a belt 100 thus produced. In certain cases, the results obtained are compared with the characteristics of a belt of the prior art, namely a round belt based on polyurethane (PU), without cords or other form of reinforcement, the circular section of which has a diameter of 6 mm, and with a tensile modulus of 250 N.

[0085] Test: Determination of the coefficient of friction of the belt of the example embodiment on a steel pulley

[0086] The coefficient of friction of the belt was determined with the experimental installation shown in [Fig. 12]. For this test, the belt 100 in the form of a single strand (not welded to be closed on itself) is arranged on a pulley P. The pulley P is chosen to be representative of a steel roller with a round groove. One end of the belt strand 100 is mounted on a mass M generating a force F of 1.75 daN (deca Newton), the other end of the belt 100 being mounted on a frame, at which the tension T exerted on the belt strand 100 is measured by a suitable measuring means S, such as a force sensor. The pulley P is rotated at a speed of 43 revolutions per minute for the two minutes of the test duration. The force measurement is then carried out at the end of these two minutes, on the still rotating pulley.

[0087] The coefficient of friction (COF) is then determined by the following relation: [Math.l] COF = (U xln (J) Or : a is the angle of winding of the belt around the pulley, namely here a = ir / 2 expressed in radians (rad), T is the tension measured at one end of the belt expressed in Newton (N), F is the force generated by the mass placed at the other end of the belt expressed in Newton (weight).

[0088] The coefficient of friction of the belt strand 100 thus tested was evaluated at 0.3.

[0089] After specifying all the characteristics of the belt 100 according to the exemplary embodiment and in particular the traction modulus and the coefficient of friction on a steel pulley, representative of a round groove roller of a conveyor, tests were carried out to verify the performance of the belt 100.

[0090] Result 1: Determination of the maximum transmissible torque

[0091] Tests to determine the maximum transmissible torque of the belt 100 as well The experiments carried out were carried out on a test bench comprising two pulleys, one driving and one receiving, simulating two rollers of a conveyor. The driving pulley rotates at 305 revolutions per minute. A resistive torque is gradually applied in steps of 0.1 Nm (Newton meter) to the receiving pulley so as to slide the belt on the pulley. This torque defines the abscissa of the graph shown in [Fig. 14] and described later.

[0092] When the belt 2, 100 is engaged in the groove 12, it has a certain adhesion with the bottom 14 of the groove 12, which allows the roller 10 to be driven. This adhesion will resist a tangential force on the surface of the belt 2, 100 up to a certain limit on the torque. If this limit is exceeded, there is then slippage and therefore no more drive. Concretely, this is manifested by slippage of the belt 2, 100 in the groove 12.

[0093] The overall slip p can then be calculated according to the relation [Math.2] n _ ( ) y 1 GD P — P v Or : p is the overall slip, expressed as a percentage (%), Rm and Rr are respectively the radius of the driving pulley and the radius of the receiving pulley, each expressed in meters (m), and com and cor are respectively the angular velocity of the driving pulley and the angular velocity of the receiving hen, each expressed in radians per second (rad / s).

[0094] Thus, when the maximum torque is reached, that is to say when the receiving pulley locks and its speed cor becomes zero, the slip is worth 100%.

[0095] We now turn to [Fig. 14] which shows a comparison of the evolution of the slip as a function of the torque, for a conventional round belt 2 (curve A) and for a belt 100 according to the exemplary embodiment of the invention (curve B).

[0096] Curve A shown in [Fig. 14] shows that for a round belt 2 classic the slip is 100% for a maximum torque close to 0.7 Nm Curve B shows that for a belt 100 according to the exemplary embodiment, the slip is 100% for a maximum torque close to 2.1 Nm In other words, the belt 100 has a torque transmission capacity in this case approximately three times greater than that of a classic belt 2. Concretely, this means with this exemplary embodiment that a motor roller of a conveyor 1a, 1b equipped with the belt 100 of the exemplary embodiment will be able to drive three times more slave rollers 10 than with a classic round belt 2.

[0097] Result 2: Endurance test

[0098] Endurance tests of the belt 100 according to the exemplary embodiment were carried out on a test bench simulating a curved conveyor. This test bench comprises a drive roller and a slave roller arranged next to the drive roller, but whose longitudinal axis is not oriented parallel to the longitudinal axis of the drive roller, and more precisely arranged with a misalignment angle of 6° relative to the longitudinal axis of the drive roller. The installation on the rollers of the belt according to the exemplary embodiment required an elongation of 8% relative to its resting length, which results in an installation tension of 80 N / strand (taking into account its tensile modulus of 1000 N). The term "strand" is understood to mean the portion of belt 100 intended to extend, in use, between two rollers 10. The drive roller rotates at 305 revolutions per minute. The tests were carried out at room temperature.

[0099] In order to evaluate the belt's durability over time, the test consists of repeating a certain number of 1 s / 1 s (second) on / off cycles. This means that the motor roller rotates for one second then stops for one second before restarting for one second and so on until reaching 500,000 cycles. The accelerations / decelerations linked to the on / off cycles combined with the inertia of the slave roller thus generate a resistive torque.

[0100] It has been observed that the belt according to the invention passes this endurance test with limited wear. Consequently, this means that the coefficient of friction has remained stable over time.

[0101] A similar test was carried out on a conventional round belt as described above. It was observed that the round belt came out more worn, which weakened it.

[0102] This last test marks the end of the description and results associated with the example embodiment.

[0103] It should also be noted that other tests were carried out on belts similar to that presented in the embodiment example by only modifying the rate of penetration of the knit into the teeth, in order to modify the coefficient of friction. It was thus possible to determine that the coefficient of friction should not exceed the approximate value of 0.8 because beyond this there was a risk of the belt turning over in the groove of a roller of a curved conveyor.

[0104] Consequently, the coefficient of friction of the belt 100 with the groove 12 of the roller 10 must be less than or equal to 0.8.

[0105] Advantageously, this 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 500 N and 1500 N, advantageously between 800 N and 1500 N, and preferably between 800 N and 1200 N.

[0106] Advantageously again, the coefficient of friction of the belt 100 with the groove 12 of the roller 10 is between 0.3 and 0.8, and combined with a traction modulus of the belt 100 between 500 N and 1500 N, advantageously between 800 N and 1500 N, and preferably between 800 N and 1200 N.

[0107] The invention also relates to a concave groove roller conveyor similar to the conveyors 1a, 1b illustrated in Figures 1 and 2.

[0108] This conveyor 1a, 1b comprises a plurality of rollers 10 with concave grooves 12 which are connected to each other two by two by a belt 100 as described above. The belt 100 is advantageously installed between the rollers 10 with a laying tension of between 60 N / strand and 100 N / strand.

[0109] Figures 15 and 16 show the belt 100 according to the invention engaged respectively in a concave groove 12, for example made of steel, formed in a roller 10 and in a concave groove 12 belonging to a drive head 18, for example made of plastic such as a polyamide (PA), a polypropylene (PP) or a composite material based on fibers embedded in a thermoplastic or thermosetting resin, fixed on a roller 10. In each of the two cases, the convex toothing of the ventral portion 106 of the body 102 of the belt 100 cooperates with the concave groove 12, and in particular with the bottom 14 of the groove 12. It is understood that the radius of curvature of the bottom 14 of the groove 12 is substantially equal to the radius of curvature of the toothing of the ventral portion 106 of the body 102. In this way, the contact surface between the belt 100 and the bottom 14 of the groove 12 is maximum.

[0110] In Figures 15 and 16, it can also be seen that the belt 100 is mounted in the grooves 12 of the rollers 10 of the conveyor 1a, 1b such that each belt 100 has a height H strictly less than a depth PR of the groove 12 receiving it.

[0111] As described above, the transmission capacity of the belt 100 according to the invention is at least twice as large as that of a conventional round belt 2. Consequently, the conveyor according to the invention can comprise twice as many slave rollers 10 as a conveyor equipped with conventional round belts 2. This means that, if, for example, a conventional conveyor is sized to comprise a plurality of motor rollers separated from each other by at least 3 to 5 slave rollers, then the conveyor according to the invention may comprise a plurality of motor rollers separated from each other by at least 6 to 10 slave rollers. Of course, this could be more if the conventional conveyor is sized as such.

[0112] In light of what has been described in the foregoing, it clearly appears that the belt according to the invention allows an improvement in the torque transmissible by the belt and its stability. Indeed, in use, the contact surface between the belt and the bottom of the groove of the roller is high thanks to the convex shape of the teeth of the belt which adapts to the concave shape of the groove. In addition, the combination of this convex shape of the teeth with the coating arranged at the external surface of the teeth makes it possible to define the coefficient of friction of the belt in the groove at a controlled value.With a controlled coefficient of friction and the presence of cables improving the traction modulus of the belt, the transmissible torque can be controlled as well as the levels of deformation of the belt in the event of contact with one side of the groove, which limits the risks of the belt turning over, in particular in a curved part of a conveyor.

[0113] Another advantage is that it allows for improved durability of the belt over time. In fact, thanks to the coefficient of friction that is stable over time, the belt wears less quickly, which improves its lifespan.

[0114] Yet another advantage is to reduce the costs of developing a conveyor. Indeed, thanks to the improvement in the torque transmissible by the belt according to the invention, more slave rollers can be slaved to a motor roller in a conveyor. In fact, the number of motor rollers can be reduced, representing a saving in infrastructure and energy.

Claims

Claims

1. Transmission belt (100) for a conveyor (1a, 1b) with rollers (10) having concave grooves (12) made of steel or plastic, said belt comprising: - an elastomer-based body (102) comprising a dorsal portion (104) and a ventral portion (106) formed of a single toothing, an external surface of which has a convex shape which is configured to cooperate with a concave groove (12) of a roller (10); - a set of traction cables (110) embedded in the body (102) between the dorsal portion (104) and the ventral portion (106) of said body; and - a coating (112) arranged at the external surface of the teeth defining, with the shape of the external surface of the teeth, a coefficient of friction which is not zero and less than or equal to 0.8 with the concave groove of a roller.

2. The belt (100) of claim 1, wherein the coefficient of friction is greater than or equal to 0.

3.

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

4. A belt (100) according to any one of claims 1 to 3, wherein the cords (110) of the cord assembly are made of a polyamide or polyester based material.

5. Belt (100) according to any one of claims 1 to 4, in which the coating (112), partially embedded in the teeth, is chosen from a knit, a fabric, a non-woven or a set of fibers.

6. A belt (100) according to claim 5, wherein the covering (112) is made of a material selected from polyamide, polyester, cellulosic fibers, for example cotton, a mixture of cellulosic fibers and polyurethane or a combination thereof.

7. A belt (100) according to any one of claims 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.

8. Belt (100) according to any one of claims 1 to 4, in which the body (102) is made of a material chosen from ethylene-propylene-diene monomer or ethylene-propylene copolymer, and the coating (112) is a film of at least partly crosslinked thermoplastic material, comprising at least 30% polyethylene, said thermoplastic film covering the external surface of the teeth.

9. The belt (100) of claim 8, wherein the film comprises particles and / or fibers of graphite, molybdenum disulfide and / or polytetrafluoroethylene.

10. Conveyor (1a, 1b) comprising a plurality of rollers (10) with concave grooves (12) made of steel or plastic, in which said rollers are connected to each other two by two by a belt (100) according to any one of claims 1 to 9, so that the coating (112) of the belt is in contact with the concave grooves (12) of the rollers.

11. Conveyor according to claim 10, in which said belt (100) has a height (H) strictly less than a depth (PR) of the groove (12) receiving it.

12. Conveyor according to any one of claims 10 or 11, in which the concave grooves (12) of the rollers (10) are made of a plastic material chosen from a polyamide, a polypropylene or a composite material based on fibers embedded in a thermoplastic or thermoset resin.

13. Conveyor according to any one of claims 10 to 12, wherein the belt (100) is installed between the rollers (10) with a laying tension of between 60 N / strand and 100 N / strand.

Images