FR2728852A1 - Intermittent drive conveyor carrying series of wheeled trucks - Google Patents

Abstract

The conveyor has at least one drive bar (3) close to the running track of the trucks, which moves reciprocally and cyclically, driven by a motor. The drive bar carries lever arms (9) at a spacing at least equal to the length of one truck, which have a drive hook (5) at their free ends and a transverse pivot axis (14) at their other end. A roller (10) is mounted at an intermediate point of each lever arm. The lever arms pivot cyclically between an upper position in which their hooks engage a truck, and a lower position in which they are below the level of the bottom surface of the trucks. The cyclical action is caused by contact between the roller and a cam surface defined by the shaped bottom of each truck.

Description

DESCRIPTION
The invention relates to a conveyor internittently driving vehicles which are guided on a movement track provided with guide tracks or rails, comprising at least a displacement bar with rectilinear guidance which is arranged in the region of the movement track. movement, which can be moved cyclically back and forth on a path, which is driven by a motor, the length of which is equal to that of the conveyor and on which drive hooks are arranged at a distance from each other, these being formed with a view to engaging parts of the vehicle or with projecting parts of the vehicle, being able to be alternately driven in a drive position and in a release position.

 Conveyors intermittently driving vehicles which are guided on a track can find use in different fields, such as in assembly and manufacturing workshops or for postal handling, several conveyors of this kind can also be juxtaposed in function needs. The vehicles can be mobile containers which roll on rollers or on wheels and the realization of which can be most varied, or even pallet trolleys. In general, they are characterized by a basic frame provided with roller supports and pivoting rollers with the help of which they are guided on rails or in tracks conformed in another way.

 As a general dewlap, vehicles which are brought by hand or automatically to one end of the conveyor at different tenps intervals must be moved forward by a cyclic nanometer, individually or in groups, or even in complete lines, to be accumulated on the conveyor. At the end of the conveyor, the vehicles must then be removed back to the dwarf or automatically at any time intervals. An introduced vehicle must be moved in such a way that it joins the accumulation of vehicles already formed and that it then continues to be moved with the latter under the form of a file until the first vehicle has arrived at the last place at the end of the conveyor and that it can be removed.

 Such a conveyor should operate as much as possible without maintenance and without disturbances. it must be ensured, among other things, that a safety distance will always be maintained between accumulated vehicles without damage being produced, for example, by docking. The entire installation must be insensitive to external influences such as those due to very small parts which tone or have disturbing or sinilary edges.

 We know from US patent no 2,961,973 an installation in which drive claws which can pivot against a weight are arranged on a movable displacement bar back and forth along a conveyor, and this, & a minimum distance at least equal to the length of the carriages to be moved, these claws being able to come into engagement with the lower side of the carriages. A swivel arm provided with a nonwoven roller rotating on this arm is each time placed in front of the drive claws in the direction of movement. During the movement stroke, the roller passes under another carriage than it is precisely a question of moving, which causes the pivoting arm to tilt downwards, while a spring is stretched which is connected to the clamp by its other end. When the feed dog is no longer in engagement with the carriage when running backwards, the spring also rotates it downwards, and it maintains it in this inactive position as long as the roller is in contact with the bottom of a cart. The carts first of all keep a distance between them which is equal to the length of a cart; it is only when the first carriage has reached the final position that the following ones meet directly little by little at each subsequent race without maintaining a safety distance.

 The absence of this safety distance is a disadvantage because it can occur as a result that the carts and the moved goods are damaged. Another drawback is that when the carriage is removed from the end station, there is a minimum waiting tenps which is equal to the duration of a cycle before the following carriages have joined closely and until that a next cart can be removed. in any case there are waiting times, either until all the carriages in the queue have joined, or between the movement cycles, as we have said. It is not possible to load and unload the conveyor in a regular and synchronous naniere.

 The object of the invention is to create a conveyor of the kind specified at the start in which carriages introduced at one end can also meet on the conveyor, but in any case maintaining a safety distance.

 In the conveyor according to the invention, this object is achieved by means of levers 9 an arm which are pivotally mounted, which are arranged on the displacement bar at mutual distances at least equal to a length of vehicle, and: (a) which carry at their free end a drive hook beveled towards the free end and, between their pivot axis and the entrainment hook, a roller which can rotate around an axis or a rounded slide, (b) which are each held in the release and center positions by a spring drive, (c) and which can be moved from their center position to their release position when passing in front of a vehicle, and this at by means of a part of the vehicle or of a projecting part of the vehicle which comes to bear on the roller or on the slide.

 Thus, one or more vehicles can be seized after a race to the rear of the movement bar, and they can be moved on a constant path during the next race to the front.

 The conveyor according to the invention requires only a few movable parts. it is not necessary to compensate for weights by springs, which makes it possible to avoid disturbances due for example to the relaxation of the force of a spring. However, an even more important point is that the carriages can be transported in the form of a closed queue while maintaining a safety distance. The fact that this safety distance is guaranteed eliminates the need for stop devices for forward or reverse. Trolleys brought to the conveyor at a distance in time with respect to a line of displaced carriages join the line of carriages which is placed in front of the picking station at each removal cycle, which avoids waiting times.

 The invention creates a mechanical conveyor of the kind specified at the start which is robust and insensitive to disturbances and which can operate largely without maintenance, but whose operation is very safe and reliable.

 In a very simple embodiment of the invention, a simple oblique surface can also be provided on the lever in place of the rollers or slides.

 The projecting parts or the parts of the vehicle which it is necessary to provide for the engagement of the centering hook with the vehicles may be transverse crosspieces which are in any case present on the bottom of the vehicle.

 The one-arm levers can preferably be brought back each to the entrained position with the drive hooks by a compression spring.

 The path s which is traversed during a cyclic displacement of the displacement bar in the two directions corresponds at least to the length 1 of a vehicle.

 In another embodiment of the invention, this path s corresponds to the length 1 of a vehicle increased by a safety distance a.

 According to a particularly preferred embodiment of the invention, the path s is greater by a minimum value than the length 1 of a vehicle increased by a safety distance a.

 In another embodiment of the invention, the drive hooks can also be moved from their rest position maintained by the force of a spring to their position of movement by means of a magnetic or motor drive which can be controlled by a switching pulse, which can be triggered by the vehicle.

 The one-arm levers are pivotally mounted on the displacement bar at a mutual distance which is each time equal to the path traveled s or s + a, respectively.

 The vehicles can be provided with rollers or wheels mounted at a distance in the transverse and longitudinal directions, or they can be guided in rails by means of pads.

 The displacement bar can be guided on rollers with fixed axes or between pairs of rollers with 9 fixed axes.

 A reversible rack and pinion drive can be used to drive the displacement bar, or the latter can also be driven by means of a pressurized fluid cylinder.

 Thanks to its robust mechanical construction, the conveyor according to the invention offers yet a series of other advantages. Thus, it does not require an exact positioning of the vehicles during their introduction at the start of the conveyor. Vehicles can even be pushed on the conveyor or removed by hand in the direction of travel without disturbances occurring. The removal of vehicles at the end of the conveyor is possible regardless of the shift sequence of the displacement bar. Vehicles of different lengths can be moved, and it only occurs between accumulated vehicles distances that are also different and that are greater. The installation can be stopped and restarted in all positions. When the installation is stopped, all vehicles can be removed by hand forwards.

 The operation of the installation is easy and uncomplicated, and its structure is extremely easy to maintain. The control function is clearly visible and insensitive to external influences. Thanks to the choice of suitable materials, it is possible to obtain for the installation a sufficiently silent and wear-free operation. The technique can be applied to many other conveying works.

 In the following, the invention is described in more detail with the aid of the accompanying drawings.

 Figure 1 shows a perspective view of part of a conveyor according to the invention on which are shown two rolling containers which constitute a possible embodiment of vehicles to be moved.

 Figure 2 shows an enlarged perspective view of part of Figure 1, the actual displacement bar being shown with a partial cutaway.

 Figure 3 shows a part of the actual displacement bar, viewed obliquely from above, together with one of the drive hooks which are arranged on it.

 Figures 4a and 4b each show a side view of a drive hook arranged on the displacement bar, on the one hand in the drive position (Figure 4a) and on the other hand in the release position (Figure 4b ).

 FIG. 5 shows a partial side view of a vehicle which is on the conveyor, one and the same drive hook being shown in its drive position in solid lines and in its release position in broken lines.

 Figures 6a and 6b show in successive diagrams marked from a to j the process of moving several individual vehicles and one behind the other on the conveyor according to the invention.

We see in Figure 1 the movement track F of a conveyor according to the invention which comprises guide rails 1 arranged on both sides. The guide rails 1 can be shaped in a different nanier; by way of example, a U-shaped cross section and an L-shaped cross section are shown. In the guide rails 1 are guided with the aid of rollers 11 of the vehicles 2 which are shown as simple example like rolling containers such as those used among others by post. On the movement track F, and below the vehicles 2, there is the movement bar 3 which can be moved over a determined and constant stroke, first of all opposite to the direction of movement proper, then in the direction of movement, and this, under the control of a signal from a sensor and using a reversible notor which does not is not shown in the drawing. The displacement bar 3 is constituted by a profiled sheet which is folded down twice on both sides and which is guided on fixed rollers 12, these being mounted on the movement track F and covered from below by the profile of the displacement bar, as can be seen more clearly in FIG. 2. Driving members are located laterally on the displacement bar 3, at a mutual distance which corresponds at least to the length
L of a vehicle 2 increased by a safety distance a, and they can come into engagement with protruding parts 4 which are provided on the lower side of the vehicles 2 and which can be constituted by transverse crosspieces 6 mounted on the bottom 7 of the vehicles (see Figure 5).

 As shown in more detail in Figure 3, the drive member is constituted by a lever with an arm 9 which can pivot around a fixed axis 14 mounted transversely to the displacement bar 3 by means of retaining cheeks 13 and on the free end of which a drive hook is fixed 5. A roller 10 whose role will be explained below is mounted rotating about an axis on the lever 9, in a position 9 approximately central between the axis of rotation of the latter and the drive hook 5. The latter is held against a stop by a compression spring 8 in the starting position which is in this case the position of engagement or To this end, the compression spring 8 rests on the one hand on a projecting part of the lever 9 and on the other hand on a pivot 15 which is integral with the displacement bar 3.

 If a vehicle is introduced at one end of the conveyor, the drive of the displacement bar 3 is switched on by a sensor installed in the region of the start of the conveyor, and this bar is first moved on a constant stroke or on a constant path s opposite the direction of movement proper; firstly, the drive hook 5 which is first of all in front of the vehicle in the direction of movement and which slopes towards the free end passes here under the vehicle 2, then it is also the turn of the roller 10 which is mounted on the same lever 9, without the vehicle being moved. The roller 10 rolls here, either on the bottom 7 of the vehicle itself, or again on a longitudinal cross member mounted on this bottom 7. When it passes under the vehicle 2, the lever 9 pivots down around the axis 14 against the force of the compression spring 8, the drive hook 5 being brought into its release position (see Figure 4b and Figure 5 on this subject) and held therein as long as the roller 10 is in contact with the bottom 7 of the vehicle. This ensures that, during the next displacement stroke on the path s, the drive hook 5 can only come into engagement with the projecting part 4 which is specially provided for this purpose or with the transverse cross member 6 which is furthest forward when the roller 10 comes effectively to leave the bottom 7 of the vehicle and the compression spring 8 brings the drive hook 5 into the drive position. The roller 10 thus guarantees a minimum safety distance a between the vehicles 2 when these follow one another in a row, because the drive hook 5 is brought into its release position, thus no longer moving the vehicle concerned 2, even when the roller 10 is in contact with a vehicle 2 which is located in front of it in the direction of travel.

 The course of the movement is shown diagrammatically in FIGS. 6a and 6b by several stages a to j. In a, the conveyor which is still empty is indicated with the drive members, these being mounted on the displacement bar 3 at a distance equal to the length of the vehicles increased by a safety distance. vehicle is introduced at the start of the conveyor, a signal from a sensor triggers the reversible drive which is intended for the displacement bar 3 and, when taking the back stroke, the drive member which is in front the vehicle in the direction of travel passes under it, and, as described above, it is brought and maintained in the release position until, during the following forward race Immediately, the roller 10 of the drive member comes out of contact with the bottom of the vehicle, that the drive hook 5 comes into engagement and that the vehicle is moved to the first location of the conveyor, such as is schematized in b. on the neck next CSR to the rear, the same drive member passes under the first vehicle over its entire length and also still, in part, under the next vehicle which is ready, however it is kept permanently in its release position , either by the oblique part of the drive hook 5, or by the roller 10; no movement therefore takes place during a backward stroke. The drive member of the next place passes under the first vehicle as described. In the next rearward stroke, the drive members engage with the respective vehicles, and shift them by one place.

This then occurs exactly the same way for the following vehicles, as shown in diagrams in c, d and e.

 It was then assumed in f that no additional carriage was first introduced into the conveyor after the fourth vehicle. The reversible drive, however, continues to be in action, and it continues to move the four vehicles in a line during each cycle until the first vehicle has reached the end of the conveyor, that is, its last location. It is only then that a signal from a sensor interrupts the reversible drive, and therefore the movement operation, when the direction of movement of the movement bar is reversed. This process is shown in f, g and h in Figure 6b. It should be noted that only two sensors are required in total in this conveyor according to the invention, one recording the fact that a vehicle is ready at the start of the conveyor and the other detecting the arrival at the last location.

 If other vehicles are introduced into the conveyor, they are moved with the others in the manner previously described, at a distance from the vehicle queue, as long as the first vehicle is not yet at the last location. If then the first vehicle has reached the latter location, the vehicle which has been introduced at a distance from a distance continues to be moved until it has reached the end of the queue. No force tending to move is exerted on the line of vehicles which is located at the front, since the drive members concerned are kept in their release position. If a vehicle reaches the end of a stationary vehicle, the drive member passes under the stationary vehicle, and it moves the other vehicle up to a release distance fixed by construction. This is shown diagrammatically in i and j in FIG. 6b.

 If a vehicle is removed at the end of the conveyor, it no longer keeps the next drive member down in its released position, and the next vehicle is offset by one place, all other vehicles which have accumulated being trained.

 Because the drive member is only released for a distance of about 100 nn in a concrete embodiment of the invention, while the race would lead to a distance of 120 sn, the vehicles are brought together until the ninimal distance of 100 minutes during the next forward race. This effect is not annoying, and on the contrary it even leads to relieving the drives, since the vehicles are easily delayed and accelerated one after the other.

 The invention has been described on an exemplary embodiment without being related thereto; on the contrary, numerous modifications are possible without leaving the scope of the invention. For example, one can also provide on the drive member, 9 the place of the roller 10, a slide or uniquenent an oblique surface. Alternatively, the displacement bar can be arranged on the conveyor with the drive members in a position which is located laterally relative to the vehicles. It is possible to obtain a movement of the vehicles which is even quieter by means of additional rollers which are arranged on the axis 14 of the drive member and which then also roll on the bottom of the vehicle.

Claims (10)

1. Conveyor intermittently driving vehicles which are guided on a movement track provided with guide tracks or rails, comprising at least one movement bar with rectilinear guidance which is arranged in the region of the movement track, which can be moved cyclically back and forth on a path (s), which is driven by a motor, the length of which is equal to that of the conveyor and on which drive hooks are arranged at a distance from each other, these these being formed to engage parts of the vehicle or with projecting parts of the vehicle which can be alternately brought into a drive position and into a release position, characterized by one-arm levers (9) which are not swiveling, which are arranged on the displacement bar (3) at mutual distances at least equal to a length of vehicle (1), and: (a) which carry at their extrem ity free a drive hook (5) beveled towards the free end and, between their pivot axis (14) and the drive hook (5), a roller (10) which can rotate about an axis or a rounded slide, (b) which are each held in the release or drive positions by a drive & spring (8), (c) and which can be moved from their drive position to their release position when 'They pass in front of a vehicle, and this at the core of a part of the vehicle or of a projecting part (4) of the vehicle which comes to bear on the roller (10) or on the slide. 2. Conveyor according to claim 1, characterized in that the projecting parts (4) which are intended on the vehicle for the engagement of the drive hook (5) are transverse cross members (6) of the bottom (7 ) of the vehicle. 3. Conveyor according to claim 1, characterized in that the one-arm levers (9) are each returned to the drive position with the drive hooks (5) by a compression spring (8). 4. Conveyor according to claim 1, characterized in that the path (s) which is traversed during a cyclic displacement of the displacement bar (3) in both directions corresponds at least to the length (1) of a vehicle (2). 5. Conveyor according to claim 1, characterized in that the path (s) which is traversed during a cyclic displacement of the displacement bar (3) in both directions corresponds to the length (1) of a vehicle (2) increased by a safety distance (a). 6. Conveyor according to claim 1, characterized in that the path (s) which is traversed during a cyclic displacement of the displacement bar (3) in both directions is greater by a minimum value than the length ( 1) of a vehicle (2) increased by a safety distance (a). 7. Conveyor according to claim 3, characterized in that the drive hooks (5) can be moved from their drive position held by the force of a spring to their position of release to the core of a magnetic or motor drive which can be controlled by a switching pulse, which can be triggered by the vehicle. 8. Conveyor according to one of the preceding claims, characterized in that the levers with one arm (s) are pivotally mounted on the displacement bar (3) at a mutual distance which is each time equal to the path traveled (s or s + a, respectively). 9. Conveyor according to one of the preceding claims, characterized in that the displacement bar (3) is guided on rollers with fixed axes (12) or between pairs of rollers with fixed axes. 10. Conveyor according to one of the preceding claims, characterized in that a reversible pinion and rack drive serves to drive the displacenent bar (3).