FR2723359A1 - TRAY CONVEYOR - Google Patents

Abstract

A tray conveyor, comprising a plurality of independent trays (1) guided on at least one guide track (30, 31) and carried upon an air cushion, wherein the air supply is provided by said track itself, only when said tray is present upon the track and at the level thereof. The guide track includes an upper, substantially horizontal sole (31), with valve ends (3) terminating at the sole through apertures (4a, 5a) provided at regular intervals, according to the length of the trays (1) and the loads that may be carried thereupon. In dynamic operation, said valves (3) are open and discharge a compressed air jet when their apertures (4a, 5a) are covered by a tray (1), and are otherwise completely closed.

Description

TRAY CONVEYOR
The invention relates to a tray conveyor, comprising a plurality of trays independent of each other, and intended for the transport of products inside, including workshops, factories, etc.

 This device can be used as a free plate conveyor, both in the assembly line sector and for any other sector in the field of transit.

In the field of assembly, the free plate conveyors are more widespread because they meet for the most part, the needs of these lines of assemblies, and in particular
- the smoothing of hazards, that is to say the non-dependence of the progression of the trays downstream of the stop of an upstream plateau, and this, unlike special machines and other chain conveyors (s)
- product flexibility: due to the constant evolution of products, machines, especially conveyors need to be changed quickly, with the shortest possible series change times; thus, an assembly line with free plates makes it possible to have a tooling change time in hidden time;
- the flexibility of the machines and workshop: considering that there is no connection between the positions of an assembly line, and that these stations are located on interchangeable modules, the assembly range of a product can be modified at a lower cost;
- and finally, to progressive automation: the modularity of the stations of a free-plate assembly line makes it possible, for example, to create a line in manual mode and to automate, at the request, such or such a particular item.

There are two categories of free plate conveyors:
- firstly, the free-moving conveyors with active track; in such conveyors, the free trays are conveyed by adhesion by means of belts (belts or roller chains), allowing sliding for the accumulation of trays in front of the workstations and thus meeting the needs of smoothing hazards;
- free-moving passive conveyors; in such conveyors, the free trays are equipped with on-board electric motors, whose energy comes either from a battery also on board, or rolling tracks, which in this case are electrically conductive, like some subways.

 In the field of transit, the management of production flows is directly related to the performance of the conveyor. Existing equipment is distributed in the same way as above, namely active track conveyors, low-load conveyor belts or belts, or medium-duty conveyor or roller conveyors, and passive-track conveyors, including trays. become electric trolleys, wire-guided or optoguidées, and whose energy comes either from integrated rails on the ground, or from an on-board battery.

 For active track conveyors, the load capacity per platform is limited to a few kilograms. In addition, to meet the modularity of the machine, and to avoid premature wear of the conveyor belts, it is necessary to multiply the motorizations. This multiplication of engines and bands is on the one hand expensive, and on the other hand, is a source of hazards. Indeed, the greater the number of engines is important, the higher the manufacturing costs are high, and in parallel, the more the number of failures or malfunction increases. In fact, maintenance costs are also increased, and productivity is likely to be affected.

 In addition, when a conveyor belt is defective, it takes several hours to replace it, during which production is necessarily stopped. In the case of motorized pallets, the purchase, management, operation and maintenance costs of the automation systems are also very important.

 In order to overcome these various disadvantages, it has been proposed, for example in document FR-A-2 254 499, an active air-cushion conveyor. Said conveyor is provided with a plurality of orifices, divided according to the size and mass of the loads to be conveyed, and connected to a source of compressed air. These holes, in the absence of charge at their level, are partially closed so as to cause a leakage of compressed air. On the other hand, when they are covered by a load, the equilibrium of the pressures on both sides of the shutter member induces the opening of the corrresponding orifices, releasing the compressed air and creating a lift air film.

 Although such a conveyor certainly makes it possible to overcome a number of the drawbacks listed above, on the other hand, it is very much a consumer of compressed air, since conceptually a leak at each of the orifices is necessary for its proper operation. Moreover, it does not lead to a progression of the charges it receives, the air film playing a single role of sustenance.

 The object of the invention is to eliminate the various disadvantages mentioned above. It thus relates to a conveyor with independent trays, active track type, so in which no electric motor is embedded on the trays, and air cushion type, so in which there is no contact between the or transport routes and trays.

 This tray conveyor comprises a plurality of independent trays guided in at least one guideway, and resting on an air cushion, the air supply being carried out by the track itself, only in the presence of the tray on said track and at the only one level thereof, the guide path having a substantially horizontal upper sole, at which open at regular intervals, depending on the length of the trays and the loads they are likely to carry, the ends of the valves.

 I1 is characterized in that said valves are dynamic open function and release a jet of compressed air when their orifices are covered by a plate, and completely closed in the opposite case.

 In other words, the air coming from the guideways is sent into the lower cavity defined at each plate, so as to form a film of air between the track (s) and the plate, and allow them to slide. without contact on said guideway, the actual guidance being provided by the side edges of the track. Thus, the wear of the sliding surface is totally eliminated.

 In addition, the air supply is provided by air jets, coming from the guideway, and which are active only when there is a plateau at said jets, thus avoiding overconsumption of air. 'air.

 The presence of the plate at the level of the air jets is not detected by specific sensors, but by the internal pressure within the tray cavity, which, during its progression, itself drives the opening of the valves under the relevant tray, thus inducing the activation of the air jets. Thus, as soon as a flap is no longer covered by a tray, it closes automatically.

 Furthermore, the internal cavity defined by the trays, has an upper surface of clean profile, in cooperation with the orientation of the air jet delivered by the valves, suitable for inducing the progression of the trays in the direction of the guideway in one direction or the other.

 Indeed, the force required to move a plate on air cushion is relatively low, so that the shape of the inner cavity of said trays and the orientation of the jets are sufficient to ensure the progression to said plate in the desired direction. Thus, the trays can slide in turn in front of the workstations where they are stopped, either by means of mechanisms assigned to each of the stations, or by trays that precede them, thus accumulating behind each other.

 In addition, the speed of progression of the trays can be adjusted by varying the pressure and the flow of the jets.

 This gives a free-plate conveyor implementing the qualities of the principle of the air cushion. The products, of small or heavy loads, are transported in flexibility by free trays, possibly with variable dimensions, and which themselves are self-powered, directed and supported without contact, by channels with air supply incorporated.

 The manner in which the invention can be realized and the advantages which result therefrom will emerge more clearly from the exemplary embodiments which follow given by way of indication and not by way of limitation with the aid of the appended figures.

 Figure 1 is a schematic representation in perspective of a general view of the installation according to the invention.

 Figure 2 shows a schematic view of a configuration of trays and tracks.

 Figure 3 is a longitudinal sectional view of Figure 1 along the line A-A, and in particular showing a valve in the open position and a valve valve in the closed position.

 Figure 4 is a schematic view also in longitudinal section of a plate on its guide path according to a first embodiment of the invention.

 Figures 5a and 5b are views similar to Figure 4 of another embodiment of the invention, Figures 5c and 5d of which are cross-sectional views.

 Figures 6a and 6b are also diagrammatic representations in longitudinal section of another embodiment of the invention, of which Figures 6c and 6d are cross-sectional views.

 FIG. 7a shows another embodiment of the invention in which the valves are substituted by a single-wire seal, and FIGS. 7b and 7c of which are cross sections, respectively in the presence and in the absence of a plate, and whose Figure 7d is a view from above.

 Figure 8 shows another embodiment of the invention for dual channels and wide trays.

 FIG. 2 shows a plant implementing the invention. It consists of different modules that allow handling trays, with the general reference (1), to route products they transport to workstations.

 The course of these trays is of course based on the distribution of workstations within this facility. Thus, the trays (1) can move either on modules in a straight line, of a type "straight section" (9), or move on modules in a curved line (10). Moreover, the trays (I) can be stopped by stopper mechanisms (II), shown in more detail in FIG. 1, arranged along the tracks, and particularly at the workstations. These stopper mechanisms (11), and more specifically the retractable part (11a) of these mechanisms cooperate, as can be seen in Figure 1, with the outer peripheral rim (la) of the plate (1). This part (11a) can indeed retract on demand to allow the release or not the trays.

 When a plate (1) is stopped, the trays that follow can possibly accumulate one behind the other, as materialized by the reference (12) in Figure 2. In parallel, the plates (1) can be directed vertically, by means of modules of type descenceur (13) or ascenceur (14). In addition, the trays (I) can be derived by lateral displacement type modules (15), but can also be switched by horizontal curve type branching modules (17).

 The guide path (2) of the trays (1) is constituted by these different modules connected together by junction modules (16), to ensure on the one hand, the continuity of the sliding sole ( 31), but on the other hand, the extension of the supply of compressed air (29).

 This compressed air supply is provided by a main pipe (29), connected to a source of compressed air and from which is taken by the various valves (3), the compressed air necessary for the realization of the cushion of air, as described in more detail later.

 The guiding lane thus formed comprises at its upper surface the actual guide lug, plane (31), at which and in particular along its median line, open outlets (4a, 5a) of the compressed air supply valves. as well as further described later.

 The trays (1) of substantially rectangular shape comprise a base (32), intended to cooperate with the sole (31) on the one hand, and whose side walls are guided by the flanges (30) of the guideway (2). ).

 This base (32) defines an internal cavity (6) closed on its five faces, respectively the four lateral faces and the upper face, the lower face being open to allow the creation of the air cushion.

 FIGS. 3 and 4 show a first embodiment of the invention. According to this embodiment, and over the entire length of the guideway (2) is arranged in a specific pitch p, depending on the length of the trays, and the loads they are intended to carry, a series of n flaps (3).

 At rest, that is to say during the non-operation of the installation, these valves are in the closed position under the action of the pressure P1 of the compressed air of the pipe (29), and which induces the thrust of a ball (8) closing, as can be seen in Figure 3, the channel (33) connecting said valve to said pipe (29).

 These valves (3) comprise an intermediate chamber (34) divided into two parts by an elastic membrane (7), each of the two parts thus defined, respectively communicating with the channel (33) for supplying compressed air under pressure. P1, and on the other hand, with the channel (4) opening at (4a) at the sole (31) of the guideway (2).

 In addition, parallel to the channel (4), the valve comprises a channel (5) opening at one of its ends (5a) in the vicinity of the end (4a) on the sole (31) of the track (2) , and at its other end at the channel (33). The air jet used for the creation of the air cushion and the progression of the trays is emitted by this channel (5).

 Thus, in dynamic operation, when a plate (1) covers the track (2), in particular at the two ends (4a) and (5a) of a valve (3), the internal air pressure of the plate P2 , and more precisely the pressure within the cavity (6) defined by the base (32), passes through the channel (4) and will induce the application of this pressure P2 at the section of the chamber (34) in communication with said channel (4). In fact, and as can be seen in Figure 3, this membrane will deform and induce the thrust of the ball (8), which was held in the shut position under the action of the pressure Pi of the pipe (29), thereby releasing the access of the channel (5) to the channel (33), and thus the release of an air jet, and thus the pressurization of the cavity (6) underlying the plate and thus create the air cushion.

 Due to this pressure being applied to the cavity (6) at the pressure of the compressed air P1, this compressed air passes through the pipes (19) in communication with the cavity (6) at the level of the lateral skirt ( 36) of the plate, said pipes opening at the base (37) of said skirt, the base (37) being itself closed by an elastic membrane (18), which under the action of the pressure, thus comes to ensure a relative sealing the cavity (6) relative to the outside, and thus allow the realization of a real air cushion on the sole (31) of the track (2).

 Meanwhile, the upper face of the cavity (6) has a special profile (38) symmetrical sawtooth, whose edges are substantially oriented at 45 "relative to the horizontal, so that, given the inclination substantially also at 45 relative to the horizontal of the channel (5) of the valve (3), and from the resulting air jet, it follows a cooperation of the air jets with the edges of the profile (38). and therefore, the progression of the plate (1) in the direction shown by the arrow in Figures 3 and 4.

According to one characteristic of the invention, the length L of the cavity (6) defined by the two membranes (18) (FIG. 4) is greater than the pitch p between the valves. In this way, the following relationship is permanently checked
P2 x membrane surface (7)> Pi x surface of the sealing ball (8)
Thus, when the orifices (4a) and (5a) of the valves (3) are covered by the plate (1), then putting the corresponding channels (4) and (5) valves (3) in communication with the cavity (6), the channel (5) is brought into communication with the channel (33), that is to say the formation of air jets, inducing the progression of said plate. However, since a valve (3) is no longer covered by a plate (1), it is not subjected to the pressure P2 of the cavity (6) and therefore the ball (8) subject to the overpressure Pi returns to its closed position. The plate (1) advances the length of the tracks (2) by self-feeding air.

Thus, in Figure 4, the valves (3a) and (3e) are closed, while the valves (3b), (3c) and (3d) are in the open position.

 In the event of a general breakdown of compressed air, all sliding trays on the tracks (2) are stopped at the place where they are located. The sealing balls (8) of the corresponding valves are then in the open position. When the compressed air is restarted in the tracks (2), the progressive air supply makes it possible, on the one hand, to feed the trays to put them on an air cushion, and on the other hand to closing the channels (33) of the valves not covered by a plate.

 In the exemplary embodiment described illustrated in Figures 3 and 4, the direction of progression of the trays is determined by the inclination of the dams.

 In another embodiment shown in Figures 5a to 5d, the channels (4) and (5) from the valves are directed perpendicular to the sole (31) of the channel (2). In this embodiment, the internal cavity (6) defined by the base (32) of the plate, has an internal profile (38) capable of being moved within the cavity itself in a direction perpendicular to the direction of progression of the plateau, these movements being controlled on demand by an actuator located at a specific workstation. In fact, this profile (38) has two parallel series of saw teeth, said saw teeth being asymmetrical with respect to the normal to the upper surface of said cavity (6), the asymmetry of the row (38a) being opposite. the asymmetry of the other row (38b) of said profile. Thus, according to the selected row of the profile (38a) or (38b), a progression is obtained in one direction or the other of the plate, the vertically directed jets meeting the inclined surfaces, in particular oriented substantially to plus or minus 45 "by In fact, the direction of progression of the trays is directed from right to left in Figure 5a, and from left to right for Figure 5b.

 In another embodiment shown in connection with Figures 6a to 6d, the channels (5) of the valves are also oriented perpendicular to the surface of the sole (32) of the channel (2). When said valves are covered by a plate (1), they actuate a turbine (21) whose axis of rotation is parallel to the direction of progression of said plate within the channel (2). This turbine (21) actuates, by means of a gearbox (23), one or more wheels (22), of axis of rotation perpendicular to the direction of progression of the plate, and susceptible, when said plate is on air cushion, to bear on said sole (32) and thus, by the actuation by the turbine, to ensure the progression in one direction or the other of said plate. As can be seen in FIGS. 6c and 6d, said turbine (21) is capable of being displaced laterally, ie in a direction perpendicular to the direction of progression of the plate, within the cavity (6) said plateau. In this way, according to its position relative to the outlet (5a) of the air jet, the turbine (21), receiving at its vanes said jets, rotates in one direction or the other and therefore, the wheels (22) are driven in one direction or the other. The actuator can thus select the direction of progression of the plate.

 In another embodiment described in connection with FIGS. 7a to 7d, the valves (3) are replaced by an elastic single-wire joint (25), for example made of silicone, which is provided with a certain number of orifices ( 26), for example oriented at 450 relative to the horizontal and likely to create, when covered by a plate (1), air jets like the jets emitted by the valves described above. Thus, as can be seen in FIGS. 7b and 7c, when the seal is not covered by the plate (1) (FIG. 7c), the pressure Pi of the compressed air is confined in the channel (2) to level of a conduit (40). On the other hand, in the presence of a plate (1), the action of the internal pressure F2 of the cavity (6) deforms the seal (25) from top to bottom and thus releases the pressure Pi via said orifices ( 26).

 In the event of a general air cut, the trays (1) then rest on the tracks (2). Meanwhile, the piece (24) integral with the profile (38) placed against the upper surface of the cavity (6), bears on the seal (25). Thus, when the compressed air is restarted, the cavity (6) is supplied with compressed air and thus the air cushion can be recreated. As in the case of the previous example, the inclination of the channels (26) and the particular shape of the profile (38) give the plate its direction of progression.

 Although described in connection with trays traveling on a single track track, the invention also relates to configurations in which the track comprises two rails, such as for example shown in FIG. 8. It thus comprises a rail (2a) and a rail (2a). rail (2b), in which for example only the rail (2a) is equipped with a flap system or the like, and only the pad (27) of the plate (1) has an internal cavity (6) with a profile (38) adapted to ensure the direction of progression. Of course, the rail (2b) is also used to ensure the air cushion, the pressure P1 passing through a channel (20) in communication with the two internal cavities of said pads.

 Such a configuration is particularly suitable for heavy loads or cumbersome and bulky loads.

 It is thus understood that the invention has many advantages over the conveyors of the prior art known to date. In addition to the ease of implementation of the conveyor of the invention and its great modularity, it can also be mentioned its operation more particularly facilitated by the use of an air cushion, allowing more to carry a wide variety of loads , especially in terms of mass.

Claims (9)

 1 / Tray conveyor comprising a plurality of independent trays (1) guided along at least one guideway (30, 31), and resting on an air cushion, the air supply being carried out by the track itself , only in the presence of the plate on said channel and at only one level thereof, the guide path comprising a substantially horizontal upper sole (31), at which open through openings (4a, 5a) at regular intervals, function the length of the trays (1) and the loads they are likely to carry, the valve ends (3), characterized in that, in dynamic operation, said valves (3) are open and release a jet of air compressed when their orifices (4a, 5a) are covered by a tray, and completely closed in the opposite case.  2 / tray conveyor according to claim 1, characterized in that the plates (1) has an internal cavity (6), defined laterally by a lateral skirt (36), whose base (37) is closed by an elastic membrane ( 18), said skirt (36) integrating a pipe (19) communicating with the interior of the cavity (6) and opening at the base (37), so that, under the action of the pressure prevailing at the inside the cavity (6), pushing the diaphragm (18) against and resting on the sole (31) of the track (2), and thus ensuring a certain sealing of said cavity (6) with respect to the outside.  3 / tray conveyor according to claim 2, characterized in that the internal cavity (6) has at its upper surface a profile (38), intended in cooperation with the compressed air jets emitted by the valves (3). in a determined orientation, to induce the progression of the trays (1) in a specific direction.  4 / tray conveyor according to claim 3, characterized in that the profile (38) is formed according to symmetrical sawtooth, and in that the jets emitted by the valves have an orientation substantially close to 45 "relative to the horizontal.  5 / tray conveyor according to claim 3, characterized  in that the profile (38) has two parallel series of saw teeth, said sde teeth being asymmetrical with respect to the normal to the upper surface of said cavity (6), the asymmetry of the row (38a) being opposite to the asymmetry of the other row (38b) of said profile,  in that said profile (38) is capable of being displaced within the internal cavity (6) of the plate in a direction perpendicular to the direction of progression of said plate,  and in that the jets of compressed air are oriented vertically and upwardly, so as to cooperate with the indented surfaces of the rows (38a) or (38b) of the profile (38) to ensure the progression in one direction or in the other of the plateau.  6 / tray conveyor according to claim 3, characterized by:  in that the profile (38) is constituted by a turbine (21) whose axis of rotation is oriented parallel to the direction of progression of the plate, said turbine (21) actuating, via a gearbox with an angle of rotation, one or more wheels (22) having an axis of rotation perpendicular to the direction of progression of the plate, and capable, when said plate is on an air cushion, to bear on the sole (32) ,  in that said turbine (21) is capable of being displaced within the internal cavity (6) of the plate in a direction perpendicular to the direction of progression of said plate,  and in that the jets of compressed air are oriented vertically and upwardly, so as to cooperate with the blades of the turbine, so as to induce its rotation, and hence that of the wheels (22) and thus the progression in one direction or the other of said plateau.  7 / tray conveyor according to one of claims 1 to 6, characterized in that the valves (3) generating in connection with the pipe (29) compressed air air jets, comprise  - a channel (33) for connection to the line (29) supplying compressed air, communicating on the one hand, with the sole (31) by means of a second channel (5), opening at (5a) to level of said sole (31), and secondly with an inner chamber (34), split into two parts by means of an elastic membrane (7);  - a channel (4), also opening at the sole (31) by an orifice (4a), and the other end is in communication with the other part of the inner chamber (34); said channel (33) being closable, upstream of the chamber (34) and the channel (5) by means of a closing ball (8) in the absence of a sufficient pressure within the internal chamber ( 34).  8 / tray conveyor according to one of claims 1 to 6, characterized in that the jets of compressed air are emitted by a compressible wire seal (25) in connection with a compressed air pipe (40), said seal wired releasing the compressed air supply at the plateau when in the compressed position, and stopping it when it is not compressed, ie, in the absence of a plateau at the level of the channels (26) emerging from said seal.  9 / tray conveyor according to one of claims 1 to 8, characterized in that the guideway comprises two rails (2a, 2b) parallel, at least one (2a) is equipped with a valve system or equivalent and an internal cavity (6) profile (38) adapted to ensure the direction of progression, the two cavities of the pads (27, 28) of the plate being implemented to ensure the realization of the air cushion, said cavities being in communication by means of an internal pipe (20).