FR3026029A1 - DEVICE FOR CLEANING A CRIBLE - Google Patents

Abstract

The present invention relates to a device (13) for cleaning a screen (11), comprising: - at least two parallel fixed rails (18, 19), arranged near the screen; and - a carriage (15) movable blowing; said carriage comprising: - a frame (16) provided with means (20, 73) for moving along the fixed rails; and - blowing nozzles (28, 29) connected to means (32, 33, 48, 49) for supplying compressed air, said nozzles being directed towards the screen. The invention also relates to a screening installation (10) comprising such a device.

Description

The present invention relates to a device for cleaning a screen, and to a screening installation comprising such a device. Known screening facilities are particularly intended to separate materials, including waste, according to their particle size. In particular, it is known to use trampoline screens. This type of screen consists of a strip comprising several layers of perforated elastic fabric, attached to transverse bars. The bars are subjected to a linear reciprocating movement that alternately tension and relax portions of webs, bouncing the material deposited on the web. The movement of the bars distorts the mesh of the canvas, avoiding the jamming of particles in the holes. However, in the case of household waste sorting facilities, long fibers are likely to be positioned astride between two holes, causing clogging of the fabric by clogging.

It is therefore necessary to regularly unclog these screens in order to evacuate the long fibers. Unclogging is usually done by manual brushing, or blowing by means of a compressed air apparatus manipulated by an operator. Such operations are tedious and time consuming, especially since screening fabrics can be several meters long.

There is therefore a need for a device facilitating the unclogging of screens, in particular trampoline screens. To this end, the present invention relates to a cleaning device of the aforementioned type, comprising: at least two fixed rails intended to be arranged near the screen, respectively according to a first and a second parallel axes; and a mobile blowing carriage. Said carriage comprises: a frame provided with displacement means along the fixed rails; and blowing nozzles connected to means for supplying compressed air, said nozzles being intended to be oriented towards the screen. According to other advantageous aspects of the invention, the device comprises one or more of the following characteristics, taken separately or according to all the possible technical combinations: the means for supplying compressed air comprise: at least one channel of air supply, carried by one of the fixed rails; an air manifold carried by the frame and connected to the blowing nozzles; said fixed rail and the frame comprising means for passage of compressed air between the supply channel and the air collector; - The compressed air passage means between the channel and the collector comprise: an inlet port carried by the air collector and disposed vis-à-vis the channel; a valve carried by the channel, said valve being movable between a closed position and an open position, said open position allowing an air passage out of the channel; means for passage of the valve from a closed position to an open position in contact with the air manifold, so as to connect the air supply channel to the inlet port of the manifold; the channel comprises a series of valves distributed over a length of the fixed rail, a distance between two consecutive valves being less than one dimension of the inlet orifice along the axis of the rail. The present invention further relates to a screening apparatus, comprising: a band-shaped screening screen substantially disposed along a third axis; a device for moving the screening strip; and a cleaning device as described above; the third axis being arranged parallel to the first and second axes and the carriage of the nozzle nozzles being oriented towards the screening screen. According to other advantageous aspects of the invention, the installation comprises one or more of the following characteristics, taken separately or according to all the possible technical combinations: the installation comprises a housing situated at one end of the fixed rails according to the first and second axes, said housing being adapted to receive the carriage. - The installation comprises two cleaning devices as described above, said two devices being arranged on either side of the screen fabric. The present invention further relates to a method of operating a screening plant as described above, comprising the steps of: moving the screening strip; then immobilization of the screening strip; then triggering, by said immobilization, the movement of the movable carriage along the fixed rails and the air blowing through the nozzles in the direction of the screening strip. Preferably, the installation comprises a housing as described above; during the motion of the screening strip, the carriage is received in the housing, and after moving the carriage along the fixed rails, the carriage returns to the housing. The present invention further relates to a screening installation as described above, provided with means for implementing a method as described above.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the drawings in which: FIG. 1 is a perspective view of a screening installation according to a embodiment of the invention, FIG. 2 is a perspective view of a cleaning carriage of the installation of FIG. 1; FIG. 3 is a detail view, in longitudinal section, of a device FIG. 4 is a partial cross-sectional view of the device of FIG. 3, and FIG. 5 is a diagrammatic representation of a device for operating the installation of FIG. FIG. 1 comprises a screen 11 of elastic material, in the form of a band substantially disposed along a first axis 12. For example, a length of the fabric 11 along axis 12 is about 7 meters. Preferably, the fabric 11 is part of a trampoline screen. The axis 12 is shown horizontally, however it is possible to arrange the fabric 11 in an inclined manner with respect to the horizontal. In Figure 1, the fabric 11 is shown substantially planar. However, the fabric 11 is preferably arranged so as to form waves, especially if said fabric 11 is part of a trampoline effect screen. The screening screen 11 is equipped with a movement device which will be discussed later, so as to alternately tension and relax portions of the fabric. The screening installation 10 comprises a device 13 for cleaning the fabric 11.

The device 13 comprises a carriage 15 disposed above the fabric 11. The carriage 15 comprises a chassis 16 of substantially elongate shape, perpendicular to the axis 12. The carriage 15 further comprises means 17 for moving along the two rails 18, 19 fixed. In the embodiment described here, the means 17 are sliding pads. Preferably, the pads 17 are coated with a low friction film, for example containing PTFE (or Teflon). The displacement of the carriage 15 is for example ensured by traction chains 20, connected to a motorization means which will be mentioned later. The rails 18, 19 of the device 13 are respectively disposed along a second axis 22 and a third axis 23. The axes 22, 23 are arranged parallel to each other and to the first axis 12.

In the example shown in Figure 1, the rails 18, 19 are disposed above the web 11, on either side of said strip, the axes 22, 23 forming a substantially horizontal plane. A length of the rails is preferably substantially equal to, or slightly greater than, a length of the fabric 11. According to one embodiment, at least one of the ends of the rails 18, 19 is provided with a housing (not shown) capable of to receive the carriage 15 when the latter is not in operation. The carriage 15 is shown in FIG. 2 in a perspective view, from a point of view opposite to that of FIG. 1, with respect to the plane of the axes 22, 23. The frame 16 comprises two ducts 24, 25 substantially aligned in a fourth direction. horizontal axis 26, perpendicular to the second and third axes 22, 23. Each duct 24, 25 communicates with nozzles 28, 29 for blowing, distributed regularly over a length of the duct. In the embodiment shown in FIGS. 1 and 2, each duct 24, 25 is connected to thirteen nozzles 28, 29. By way of example, a duct 24 or 25 measures approximately 1 m along the axis 26 and the nozzles 28. or 29 are spaced about 7.5 cm apart along the conduit. Preferably, the nozzles used are composed of several parallel channels located in the same plane to form a set called "knife" or "scraper". The multiple air jets exiting each nozzle are straight and have a large impact force at a compressed air pressure of less than 7 bar. Typically, the impact range of these jets is less than 180 mm. The conduits 24, 25 and the nozzles 28, 29 are arranged symmetrically with respect to a plane of symmetry of the frame 16, said plane of symmetry being vertical and parallel to the axes 22, 23.

As shown in Figure 1, the nozzles 28, 29 are oriented towards the web 11 screening. Preferably, a distance between an outlet of the nozzles 28, 29 and the fabric 11 is about 15 cm. The direction of the nozzles is oblique with respect to the first axis 12 in a vertical plane. Preferably, the direction of the nozzles forms with the first axis 12 an angle of between 30 ° and 90 ° elferentially close to 45 °.

Preferably, the nozzles are oriented forwardly with respect to the direction of movement of the frame 16 along the rails 18, 19. According to one variant, it is possible to orient the nozzles substantially perpendicularly to the axis 12 and to the surface 11. The frame 16 carries two collectors 32, 33 of air, positioned laterally on either side of the plane of symmetry of the frame 16. An inlet mouth 36, 37 of each duct 24, 25 is connected. to a collector 32, 33.

The collector 32 connected to the duct 24 is particularly visible in FIG. 2. The description below of the collector 32 and the duct 24 also applies to the other collector 33 and to the other duct 25. A lateral face 40 of the manifold 32 has an orifice 41 of air inlet. In the embodiment shown in FIG. 2, the orifice 41 is in the form of two longitudinal slots, located one above the other and separated by a blade 42. The face 40 of the collector 32 is intended for come into contact with a rail 18, as shown in Figure 1. In order to press the face 40 against the rail 18, the frame 16 is connected to the collector 32 by compression springs 43. Some of the springs 43 are shown in detail in Figures 3 and 4. A similar device connects the frame 16 to the other manifold 33. In the example shown in Figure 2, the conduit 24 has two mouths 36, 44 of air inlet. Each of said mouths connects one end of the manifold 32, along the second axis 22, to one end of the duct 24 along the fourth axis 26. This air supply at each end of the duct 18 facilitates a pressure equalization in the nozzles 28. Each end of the face 40, along the axis 22, is connected to a tab 45, 46. With respect to the face 40, the tabs 45, 46 deviate from the rail 18 and are inclined towards the other rail 19. A tab 45, shown in detail in Figures 3 and 4, thus forms a ramp 47 oriented obliquely with respect to the side face 40 of the manifold 32. The other tab 46 has a similar shape. The rails 18, 19 comprise channels 48, 49 able to transfer compressed air to the collectors 32, 33. The channels 48, 49 are respectively disposed along the second axis 22 and the third axis 23. A channel 48 is visible in FIG. longitudinal section in Figure 3 and in cross section in Figure 4. The channels 48, 49 are equipped with valves 50 arranged at regular intervals along the axes 22, 23. Preferably, a distance 51 (Figure 1) between two valves 50 consecutive on a channel 48, 49 is less than a length 52 (Figure 2) slots forming the inlet port 41 of the collectors 32, 33.

A valve 50 of the channel 48 is shown in detail in FIGS. 3 and 4. The description below of the channel 48 also applies to the other channel 49. The valve 50 comprises a compression coil spring 53 located at Inside the channel 48. The spring 53 is arranged transversely with respect to the axis 22. One end 55 of the spring 53 is integral with a wall of the channel 48. Another movable end of the spring 53 is connected to a plug 56, said plug being also located inside the channel 48. In a so-called closed position of the valve 50, the spring 53 plates the cap 56 against an orifice 57 of a wall 58 of the channel 48, so as to obstruct said orifice. An outer face of the wall 58 is intended to come into contact with the lateral face 40 of the manifold 32. On the plug 56 is mounted a ball 60. When the plug 56 is pressed against the wall 58, the ball 60 passes through the orifice 57 and forms an outward projection channel 48. The ball 60 is rotatable relative to the cap 56, about an axis perpendicular to the second axis 22 and the fourth axis 26. More specifically, the ball is adapted to rolling against the collector 32 when said collector moves along the axis 22.

In the closed position of the valve 50, the spring 53 is in a partially compressed state, so as to exert a force towards the plug 56. A pressure exerted in the opposite direction on the ball 60 and / or the plug 56 increases the compression of the spring 53 and discards the plug 56 of the orifice 57. In this so-called open position of the valve 50, the inside of the channel 48 is in communication with the outside via the orifice 57. As it will be explained further, the open position allows in particular to transfer compressed air into a manifold 32,33 through the orifice 41 of the collectors. The screening installation 10 further comprises an electronic device 70 for operating the installation, according to a method which will be detailed below. The device 70 is diagrammatically shown in FIG. 5. The device 70 typically comprises a program memory in which a program 71 is stored that implements the different steps of the method. The device 70 is able to actuate a device 72 for moving the screening fabric 11. The device 70 is also able to actuate a motor 73. The motor 73 is for example connected to pinions (not shown) on which the traction chains of the carriage 15 are mounted. The startup of the motor 73 moves the carriage 15 along the rails 18, 19, the pads 17 sliding on the rails. The device 70 is also able to actuate a compressor 75 which sends compressed air into the channels 48, 49.

According to a variant of the embodiment described above, the carriage 15 and the rails 18, 19 are arranged below the fabric 11, the nozzles 28, 29 remaining oriented towards the fabric 11. According to another variant, the installation 10 comprises two cleaning devices, similar to the device 13 described above. More specifically, each cleaning device comprises a carriage 15 and rails 18, 19 as described above. One of said cleaning devices is disposed above the fabric 11 and the other of said cleaning devices is disposed below the fabric 11, the nozzles 28, 29 of each carriage remaining oriented towards said fabric. An operating method of the installation 10, shown in Figure 1, will now be described. The various steps of said method are carried out by the program 71. In a first step, a screening of materials placed on the fabric 11 is carried out. The fabric 11 is set in motion by the device 72. During this step, the carriage 15 is preferably in a housing located at one end of the rails 18, 19. At the end of the screening step, the device 72 stops working. and the canvas 11 stops. The program 71 then performs a unclogging step of the web 11. The compressor 75 is started to supply compressed air to the channels 48, 49. Preferably, the supply pressure is about 5 bars. Meanwhile, the motor 73 is started to move the carriage 15 along the rails 18, 19. As an example, the speed of movement of the carriage 15 is 25 mm / s. The lateral face 40 of each of the collectors 32, 33 slides along the wall 58 of each of the channels 48, 49. When a lug 45 located at the front of a collector comes into contact with a ball 60 of a valve 50, the oblique ramp 47 gradually pushes the ball 60 towards the inside of the channel 48 or 49. The orifice 57 is thus open when it is opposite the inlet orifice 41 The compressed air stream passing through the channels 48, 49 thus reaches the manifolds 32, 33. By the inlet mouths 36, 37, 44, the compressed air passes through the ducts 24, 25 and 29 arrives at the nozzles 28, 29. The nozzles 28, 29 and project air jets in the direction of the web 11 to unclog said web.

During the passage of the face 40 of the manifold in contact with the valve 50, the ball 60 rolls on the blade 42 separating the slots forming the orifice 41. The blade 42 thus holds the valve 50 in the open position. When a rear end of the face 40 arrives at the valve 50, the ball 60 comes into contact with the oblique ramp 47 of the rear tab 46. The inclination of the ramp 47 gradually releases the pressure on the spring 53, bringing the plug 56 into contact with the orifice 57. When the carriage 15 deviates from the valve 50, the latter has thus found a closed position. Preferably, the distance 51 between two valves 50 is less than the length 52 of the inlet orifice 41 of the collectors 32, 33. Thus, said collectors are always in contact with an open orifice 57 and the supply of compressed air nozzles 28, 29 are continuous during the movement of the carriage 15.

During the unclogging step, the carriage 15 travels the entire length of the rails 18, 19 while the nozzles 28, 29 blow jets of compressed air. At the end of the unclogging step, the supply of compressed air is interrupted and the carriage 15 travels the rails 18, 19 in the opposite direction to reach its housing.

Alternatively, the supply of compressed air is maintained during the course of the carriage in the opposite direction, to double the duration of the unclogging step. According to another variant, the program 71 provides several round trips of the carriage 15 on the rails 18, 19 to extend the duration of the unclogging step. In the case where the installation 10 comprises two cleaning devices 13, one being above and the other being below the fabric 11, each of the carriages 15 operates in a manner similar to that described above. . According to a first variant, the two carriages 15 move in relation to one another with respect to the fabric 11. According to a second variant, the carriages are moved in an offset manner.

Claims (10)

CLAIMS1.- Device (13) for cleaning a screen (11), of the type comprising blowing means, characterized in that it comprises: - at least two fixed rails (18, 19) intended to be arranged in the vicinity sieve, respectively according to a first and second parallel axes (22, 23); and - a carriage (15) movable blowing; said carriage comprising: a frame (16) provided with means (20, 73) for moving along the fixed rails; and blowing nozzles (28, 29) connected to means (32, 33, 48, 49) for supplying compressed air, said nozzles being intended to be oriented towards the screen. 2.- Device according to claim 1, such that the compressed air supply means comprise: - at least one channel (48, 49) for supplying air, carried by one of the rails (18, 19) fixed a manifold (32, 33) of air carried by the frame and connected to the blast nozzles, said fixed rail and the frame comprising means (41, 50, 57) for the passage of compressed air between the duct supply and the air collector. 3.- Device according to claim 2, such that the means for passage of compressed air between the channel and the collector comprise: - an inlet orifice (41) carried by the air collector and disposed opposite to -vis the channel, - a valve (50) carried by the channel, said valve being movable between a closed position and an open position, said open position allowing an air passage out of the channel, - means (42, 47) passing the valve from a closed position to an open position in contact with the air manifold, so as to connect the air supply channel to the inlet port of the manifold. 4.- Device according to claim 3, such that the channel comprises a series of valves (50) distributed over a length of the fixed rail, a distance (51) between two consecutive stages being less than a dimension (52) of the orifice d entrance along the axis of the rail. 5.- Screening apparatus, comprising: - a screen web (11) substantially arranged in a third axis (12), - a device (72) for moving the screening strip, - a device (13) cleaning according to one of the preceding claims, the third axis being disposed parallel to the first and second axes (22, 23) and the carriage of the nozzle nozzles being oriented towards the screening screen. 6.- Installation according to claim 5, comprising a housing located at one end of the fixed rails along the first and second axes, said housing being adapted to receive the carriage. 7.- Installation according to one of claims 5 to 6, comprising two devices (13) for cleaning according to one of claims 1 to 4, said two devices being arranged on either side of the screen fabric. 8. A method of operation of a screening installation according to one of claims 5 to 7, comprising the following steps: - moving the screening strip; then - immobilization of the screening strip; then - triggering, by said immobilization, the movement of the movable carriage along the fixed rails and the blowing of air through the nozzles in the direction of the screening strip. 9. A method of operation according to claim 8 of a screening installation according to claim 7, such that: during the setting in motion of the screening strip, the carriage is received in the housing, - at the end of the moving the carriage along the fixed rails, the carriage returns to the housing. 10.- Installation according to one of claims 5 to 7, provided with means (70, 71) for carrying out a method according to one of claims 8 to 9.