FR3040986A1 - TRANSPORTER BELT SCRAPER, BELT CARRIER AND CORRESPONDING SCRAPING METHOD - Google Patents

Abstract

The scraper comprises: - a supporting structure; at least one organ. At least the leading edge (19) of the scraper member (17) comprises: - a substrate layer (21) made of a first material having a Vickers hardness of between 10 and 45 GPa, facing downstream; a superstrate layer (23) of a second material different from the first material, having a Vickers hardness greater than or equal to 40 GPa, and greater than that of the first material, facing upstream, the superstrate layer (23) covering the substrate layer (21).

Description

The invention relates generally to scrapers for a conveyor belt.

More specifically, the invention relates in a first aspect a scraper for a conveyor belt traveling longitudinally from an upstream direction to a downstream direction, the scraper being of the type comprising: - a bearing structure; - At least one scraper member having a leading edge provided to come into contact with the conveyor belt, the scraper member being bonded to the carrier structure.

Conveyor belts are frequently used to transport bulk goods, such as material extracted from a mine, a site being excavated, etc.

The conveyor belt is typically arranged to have a transport strand and a return strand. The materials to be transported are loaded onto a large face of the web, which is upwardly oriented along the transport line.

In some bands, said large face, along the return strand, is facing downwards and is therefore in contact with the rollers or the support pads of the strip. This is the case in particular for the short-length strips, in which it is not possible to reverse the strip upstream of the return strand, so as to point up the large face.

This large face is soiled by the transported product. Product residues remain glued to the large face, after unloading at the end of the transport strand. At each contact between the band and one of the rollers or one of the pads, a little product is detached from the band and falls on the ground. In a few hours, a small mound of product is formed at the foot of the support station, and must be evacuated by a worker, for example using a shovel. This mobilizes a large workforce, and entails significant costs.

There are many scrapers on the market, which are used to clean the large face of the strip, at the upstream end of the return strand.

However, the effectiveness of existing scrapers is limited so that the problem of forming a product mound at the foot of the support stations is not really solved.

An example of a belt scraper is described in FR 2 976 930.

In this context, the invention aims to provide a conveyor belt scraper that is more efficient. To this end, the invention relates to a conveyor belt scraper of the aforementioned type, characterized in that at least the leading edge of the scraper member comprises: a substrate layer of a first material having a Vickers hardness included between 10 and 45 GPa, facing downstream; a superstrate layer made of a second material different from the first material, having a Vickers hardness greater than or equal to 40 GPa, and greater than that of the first material, facing the upstream direction, the superstrate layer covering the substrate layer.

The substrate layer, which is made of a relatively less hard material, will be quickly worn away due to friction against the conveyor belt. On the contrary, the superstrate layer, which is made of an extremely hard material, will not be or very little worn because of the friction against the conveyor belt. Thus, after a few days, the leading edge consists almost entirely of the superstrate layer.

The substrate layer is used bevel. At the leading edge, a narrow, tapered ridge is formed consisting almost entirely of the superstrate layer. The contact surface between the strip and the scraper member is limited to this edge and is therefore smaller than when the scraper member is new, that is to say when the substrate layer is not worn.

The superstrate layer is indeed significantly thinner than all of the two layers, namely the substrate layer and the superstrate layer superimposed on the substrate layer.

Surprisingly, it has been found that this allows an extremely efficient scraping of the conveyor belt, eliminating all deposits on the conveyor belt, or virtually all deposits. The superstrate layer due to the hardness of the second material wears only extremely slowly, so that the scraper member has a very long life. This lifetime is much higher than that of scraping wafers of the state of the art, consisting for example of tungsten carbide.

The thinness of the ridge formed almost exclusively by the superstrate layer, contributes significantly to increase the scraping efficiency.

Surprisingly, it has been found that the conveyor belt, which is typically made of rubber, is not significantly damaged by scraping although the superstrate layer is made of an extremely hard material.

The scraper may also have one or more of the following characteristics, considered individually or in any technically possible combination: the first material has a Young's modulus of between 300 GPa and 800 GPa, and the second material has a modulus of Young greater than 900 GPa; the second material comprises polycrystalline diamond particles, or monocrystalline diamond particles, or polycrystalline cubic boron nitride particles, or cubic monocrystalline boron nitride particles, or carbon nitride particles or particles of a ternary compound BNC; the second material is obtained by compression of the particles at high temperature or by sintering or electrodeposition; the superstrate layer has a thickness of between 0.4 and 1.6 mm; the substrate layer has a thickness of between 0.8 and 5 mm; the first material is a cemented carbide; - The carrier structure comprises a carrier member, each scraper member being attached to the carrier member by an adhesive; and the carrier structure comprises a device for orienting the scraper member, arranged to selectively modify an angle between the scraper member and the strip.

According to a second aspect, the invention relates to an assembly comprising: - a belt conveyor comprising a conveyor belt; a scraper having the above characteristics, the leading edge of the scraper being in contact with the strip.

According to a third aspect, the invention relates to a method of scraping a conveyor belt, the method comprising: - obtaining a scraper having the above characteristics; - scrape a large face of the conveyor belt with the scraper. Other features and advantages of the invention will emerge from the detailed description given below, for information only and in no way limitative with reference to the appended figures, among which: FIG. 1 is a simplified schematic representation of a assembly comprising a conveyor belt and a scraper according to the invention; - Figure 2 is an enlarged view of a portion of the carrier member and the wiper member of the scraper of Figure 1; and FIG. 3 is an enlarged view of a portion of the scraper member of FIG. 2. The assembly 1 shown in FIG. 1 comprises: a belt conveyor 3, comprising a conveyor belt 5; - A scraper 7, intended to scrape the conveyor belt 5.

The conveyor belt 5 is typically closed in a loop, and has a transport strand 7 and a return strand 9. It extends from a first end (not shown) to a second end 10, with rollers 11 being placed at each end. The band circulates around the rollers 11.

The transport strand 7 serves to transport materials, which are typically bulk products, for example products extracted from quarries or excavation sites. These products are deposited on a large face 13 of the strip 5, facing upwards along the transport strand 7.

The transport strand 7 flows from the first end of the web 5 to the second end 10 of the web 5, the products being unloaded from the transport strand 7 when they arrive at the second end.

The strip 5 flows empty along the return strand. Alternatively, the strip 5 is loaded along the return strand 9.

The large face 13 of the strip is turned down along the return strand 9. It carries product residues, which remained stuck to the band at the time of unloading.

The band 5 is typically rubber.

The scraper 7 is intended to scrape the large face 13 of the conveyor belt. It is positioned near the second end of the strip. It is typically located at the upstream end of the return strand 9.

In the present description, the upstream and downstream are heard relative to the direction of movement of the conveyor belt at the return strand.

Alternatively, the scraper 7 is provided to scrape the web 5 at the overturning drum 11 at the second end 10 of the web 5, or even is provided to scrape the web 5 at the transport strand 7 between the web point of unloading of the products and the turning roller 11.

According to another variant, the scraper 7 is intended to be implanted at any other point of the strip 5.

As shown in Figure 1, the scraper 7 comprises a supporting structure 15, and at least one scraper member 17 having a leading edge 19 provided to come into contact with the conveyor belt 5. The scraper member 17 is connected to the carrier structure 15 in a manner to be described below.

The leading edge 19, as illustrated in Figure 1, is in contact with the large face 13 of the conveyor belt.

The conveyor belt 5, passing to the right of the scraper 7, circulates longitudinally from an upstream direction to a downstream direction as illustrated by the arrows of FIG. 1.

According to the invention, the leading edge 19 of the scraper member 17 comprises: a substrate layer 21 made of a first material having a Vickers hardness between 1020 and 4590 HV, that is to say between 10 and GPa, facing downstream; a superstrate layer 23 made of a second material different from the first material, having a Vickers hardness greater than or equal to 4080 HV, that is to say greater than or equal to 40 GPa, and greater than that of the first material, towards the upstream direction, the superstrate layer 23 covering the substrate layer 21

Furthermore, preferably, the first material has a Young's modulus of between 300 GPa and 800 GPa, and the second material has a Young's modulus greater than 900 GPa.

Typically, the difference in hardness between the second material and the first material is greater than 10 GPa, preferably greater than 20 GPa and more preferably greater than or equal to 40 GPa.

Typically, the wiper member 17 is a determined surface wafer, the substrate layer and the superstrate layer 21, 23 extending over the entire surface of the wafer. The scraper member 17 is delimited towards the strip by the leading edge 19. It is delimited towards the upstream direction by a large upstream face 25 and towards the downstream direction, by a large downstream face 27. Typically, the large upstream faces and downstream 25, 27 are defined by the superstrate layer and the substrate layer 23, 21 respectively.

The leading edge 19 typically extends in a horizontal and transverse direction. The transverse direction is perpendicular to the longitudinal direction;

The superstrate layer 23 covers the substrate layer 21 in the sense that it is directly deposited on the substrate layer 21 and is in contact therewith. There is typically no intervening layer between the superstrate layer 23 and the substrate layer 21.

The second material advantageously comprises polycrystalline diamond particles (PCD, polycrystalline diamond), or monocrystalline diamond particles, or polycrystalline cubic boron nitride (cBN) particles, or monocrystalline cubic boron nitride particles. , or particles of carbon nitride or particles of a ternary compound BNC.

The second material is typically obtained by compressing the particles at high temperature.

More specifically, the particles are dispersed in a matrix, and the mixture is subjected to a high pressure and high temperature compression operation.

This type of material is typically used to make drill heads in the mining or petroleum field.

According to one variant, the particles are sintered or electro-deposited on the substrate layer 21.

Sintering is an operation in which the particles are mixed with a binder powder and then heated to a temperature slightly below the binder melting temperature. The particles agglomerate with each other under the effect of heat. Electroplating involves applying a continuous electric current to a substrate having a surface in contact with a liquid containing the substance to be deposited in solution in a solvent. In this case, the substance to be deposited is a biphasic comprising metal and the particles to be deposited, in solution in a solvent.

Preferably, the first material is a cemented carbide, also called cermets (ceramic metal). The cemented carbide is typically selected from the following list: tungsten carbide, titanium carbide, nickel-plated tungsten carbide. Tungsten carbide has a Vickers hardness of the order of 2040 HV, i.e., 20 GPa.

Alternatively, the first material is a case hardened steel, or a steel having a very high hardness.

In a first exemplary embodiment, the substrate layer is a steel having a hardness of about 20 GPa, and the superstrate layer comprises polycrystalline cubic boron nitride (cBN) particles, the superstrate layer having a hardness about 60 GPa.

In a second exemplary embodiment, the substrate layer is of tungsten carbide and has a hardness of about 42 GPa. The superstrate layer comprises polycrystalline diamond (PCD) particles, the superstrate layer having a hardness of about 90 GPa.

The superstrate layer advantageously has a thickness of between 0.4 and 1.6 mm, preferably between 0.5 and 0.8 mm. It has for example a thickness of 0.6 mm. Such a thickness is sufficiently small to constitute, after wear of the substrate layer 21, a thin leading edge, having a reduced contact surface with the strip. This thickness is large enough that the superstrate layer, and in particular the leading edge, has sufficient mechanical strength not to break.

The substrate layer 21 has a thickness of between 0.8 and 5 mm, preferably between 0.9 and 3 mm, and is for example 1 mm. This thickness should not be too great, so as not to unnecessarily increase the cost of the scraper member, and to allow the rapid formation of an attacking edge constituted almost exclusively by the superstrate layer 23. On the other hand, it does not must not be too thin, so as to confer a certain rigidity and a certain mechanical resistance to the scraper member 17.

The supporting structure 7 is of any suitable type. It is for example of the type described in the patent published under the number FR 2 976 930. In any case, the carrier structure 7 comprises a carrier member 29 to which each scraper member is fixed.

Typically, each scraper member 17 is fixed to the carrier member 29 by an adhesive 30 (see FIG. 3), and more specifically by a two-component metal glue.

Such a method of attachment allows great flexibility in the implementation of the wiper members 17. Furthermore, the bonding provides flexibility to the connection between the scraper member and the support member, and allows good absorption of vibrations resulting from the running of the strip in contact with the scraper member.

In a variant, the scraper member 17 is fixed by fastening members such as screws or tie rods to the carrier member 29.

Typically, the scraper comprises a plurality of scraper members 17, juxtaposed transversely next to each other, so as to cover the entire transverse width of the strip 5.

The scraper members 17 are preferably all attached to the same carrier member 29.

Advantageously, the carrier structure 7 comprises a device 31 for orienting the scraper member 17, arranged to selectively modify the angle α, formed between the or each scraper member 17 and the strip 5.

Indeed, it has been found that the effectiveness of the scraping was greater if the scraper member was not perpendicular to the strip 5. The angle a, here corresponds to the angle formed between the superstrate layer 23 and the large face 13 of the strip, taken at the level of the contact zone of the large face 13 with the scraper member 17.

Preferably, this angle a is between 60 ° and 120 °.

An angle of 120 ° corresponds to a rotation of the scraper member 17 upstream. An angle of 60 ° corresponds to a rotation of the scraper organ 17 downstream.

It has been observed that the scraping is more effective when the angle a varies between 90 ° and 120 °, a little less effective when the angle has varies between 90 ° and 60 °, and still a little less effective when the angle has is close to 90 °.

The orientation device 31 is of any suitable type, and is for example of the type described in the application published under the number FR 2 976 930.

For example, the support structure 15 comprises a frame 33, the orientation device 31 being arranged to move in rotation the carrier member 29 relative to the frame 33 about a substantially horizontal and transverse axis of rotation X, as shown in FIG. Figure 1.

As a variant, the carrier member 29 is not orientable with respect to the frame 33. On the other hand, the carrier member 29 is arranged in such a way that each scraper member 17 can be mounted in different positions on the carrier member 29, each position corresponding to a different orientation with respect to the band 5.

According to yet another variant, the scraper 7 comprises several different carrier members. Each carrier member corresponds to a different orientation of the scraper members 17 with respect to the band 5. Thus, to change the orientation of the scraper members relative to the band, the scraper members of the carrier member are disassembled, and they are wound on another carrier member, to give the scraper members the desired angle with respect to the band.

The operation of the belt conveyor and scraper will now be detailed.

When the belt conveyor 3 is operating, the conveyor belt 5 moves around the overturning drums 11. The return strand 9 of the conveyor belt circulates longitudinally from the upstream direction to the downstream direction as evidenced by the arrows of FIG. The leading edge 19 of the scraper member 17 is applied in contact with the conveyor belt 5, and more precisely with the large face 13 of the conveyor belt at the return strand 9.

We see in Figure 1 that the contact between the scraper member 17 and the band 5 causes a slight deformation of the band 5 upwards. The orientation of the scraper member 17 with respect to the band is chosen and adjusted, by mounting the scraper members on a carrier member 29 of the form provided for this purpose, and / or by using the orientation device 31, which allows to modify the position of the carrier member 29 with respect to the frame 33.

When the wiper member 17 is new, the substrate layer 21 and the superstrate layer 23, at the leading edge 19, have substantially the same shape. They are superimposed along the leading edge 19 and therefore extend towards the strip substantially to the same level, as illustrated in phantom in FIG.

The strip 5 rubs on the edge of the substrate layer 21 and on the edge of the superstrate layer 23.

Due to the difference in hardness between the substrate layer 21 and the superstrate layer 23, the substrate layer 21 will wear much faster than the superstrate layer 23.

Thus, after a few days, and as illustrated in Figure 3, the superstrate layer 23 will be practically not worn. On the contrary, the substrate layer 21 will be worn, so that a difference in level is created between the substrate layer 21 and the superstrate layer 23 at the leading edge 19. FIG. scraper member 17 in section, in a vertical plane containing the longitudinal direction. It can be seen that the substrate layer 21 is worn in a bevel, this wear being more pronounced at the level of the large downstream face 27, and going down to the superstrate layer 23. Thus, the superstrate layer 23, at the level of the leading edge, is prominent with respect to the substrate layer 21, and creates an edge protruding towards the strip with respect to the greater part of the substrate layer 21.

This helps to increase scraping efficiency. Indeed, the pressure exerted increases because the surface in contact decreases.

Claims (11)

1. -Racleur (7) for a conveyor belt (15) flowing longitudinally from an upstream direction to a downstream direction, the scraper (7) comprising: - a bearing structure (15); - At least one scraper member (17) having a leading edge (19) adapted to come into contact with the conveyor belt (5), the scraper member (17) being bonded to the carrier structure (15); characterized in that at least the leading edge (19) of the scraper member (17) comprises: - a substrate layer (21) of a first material having a Vickers hardness of between 10 and 45 GPa, facing the downstream direction; a superstrate layer (23) made of a second material different from the first material, having a Vickers hardness greater than or equal to 40 GPa, and greater than that of the first material, facing upstream, the superstrate layer (23) covering the substrate layer (21). 2. - Wiper according to claim 1, characterized in that the first material has a Young's modulus of between 300 GPa and 800 GPa, and the second material has a Young's modulus greater than 900 GPa. 3. - Wiper according to claim 1 or 2, characterized in that the second material comprises polycrystalline diamond particles, or monocrystalline diamond particles, or particles of polycrystalline cubic boron nitride, or particles of monocrystalline cubic boron nitride, or particles of carbon nitride or particles of a ternary compound BNC. 4. - scraper according to claim 3, characterized in that the second material is obtained by compression of the particles at high temperature or by sintering or electroplating. 5. - Wiper according to any one of the preceding claims, characterized in that the superstrate layer (23) has a thickness of between 0.4 and 1.6 mm 6. - scraper according to any one of the preceding claims, characterized in that the substrate layer (21) has a thickness of between 0.8 and 5 mm 7. - scraper according to any one of the preceding claims, characterized in that the first material is a cemented carbide. 8. - Wiper according to any one of the preceding claims, characterized in that the carrier structure (15) comprises a carrier member (29), each scraper member (17) being fixed to the carrier member (29) by an adhesive . 9. - Wiper according to any one of the preceding claims, characterized in that the carrier structure (15) comprises a device (31) for orienting the scraper member (17), arranged to selectively modify an angle (a) between the scraper member (17) and the strip (5). An assembly (1) comprising: - a belt conveyor (3) having a conveyor belt (5); - A scraper (7) according to any one of the preceding claims, the leading edge (19) of the scraper member (17) being in contact with the strip (5). 11. - Method of scraping a conveyor belt (5), the method comprising: - obtaining a scraper (7) according to any one of claims 1 to 9; - scrape a large face (13) of the conveyor belt (5) with the scraper (7).