Sorting machine with always tilted transportation planes

Abstract: A sorting machine of the type comprising a plurality of dollies each provided with a rotating mat forming a transportation and discharging plane for the objects and in which means are provided suited to keep the dollies in a tilted position during the displacement along their path, wherein each dolly is provided with a pair of idle wheels which run along a guide that is so shaped as to form two superposed guide, the front and rear rolls of the dolly respectively rolling along these paths so as to maintain the dolly in an inclined position. To perform the discharging operation a rack is provided, mounted on movable support, which is displaced until it engages a toothed wheel mounted on the shaft of one of the support rolls of the rotating mat.

Description: The present invention proposes a switching machine of the type comprising a plurality of dollies each provided with a rotating mat forming a transportation and discharging plane for the objects, in which said dollies move keeping the tilted position. Each dolly is provided with a pair of idle wheels which are arranged on the same side of the dolly and glide whitin superposed rails so as to keep said wheels at different heights, thereby tilting the dolly. On the shaft of at least one of the support rollers for the rotating mat a gear wheel is mounted that at the time of discharge is engaged by a rack, thereby actuating the rotation of the mat that discharges the object into underlying collecting devices. Switching apparatuses in which the objects to be switched are laid down onto a transportation plane consisting of a rotating mat mounted on a dolly that is dragged along a fixed path are already known. When the dolly passes in correspondence with the collection devices that are to receive the object, the electronic apparatuses that control the plant actuate the rotating mat to carry out the discharge operation. One of these switching machines is known from the patent application MI A 2213 dated 06.08.91, published under the number IT-B-1254117 on the 08.09.95, after the priority date of the present document. In some of these switching machines the collection devices are arranged to the side of the dolly path and the rotating mat moves consequently in a direction that is orthogonal to the advacement direction. This system has however the drawback of being quite bulky and, most of all, of requiring an extremely heavy management of the machine because both the position of the object on the transportation plane and the discharge speed are to be controlled with the highest precision in order to avoid mistakes. Apparatuses in which the collection devices are arranged below the dollies are also known, said dollies being titled at the time of discharge in order to let the object fall into an underlying container. Such an apparatus is disclosed, e.g., in EP-A2-0611713, which proposes a handling-switching apparatus in which the pieces to be handled are placed on conveyor tables constituted by rotating carpets that are inclined and set to rotation to unload the piece into collecting vessels suitably preset: Means are provided to control the unloading of the piece, that are operated and subsequently brought again to a non-operative position by the carriage itself while it moves forward; so as to avoid the risk of breakage. The carpets are inclined at the moment of unloading only. The present invention relates to an apparatus of this kind, but it is distinguished in that the dollies are kept in a tilted position along the whole path. This feature provides marked simplifications in the management of the machine because, in order to put the mat in rotation at the precisely right moment, even mechanical means can be provided, said mechanical means being easily implemented and working reliably. The present invention will now be described in detail in a merely examplarily, non-limiting way with reference to the enclosed figures, in which: figure 1 is a perspective schematic view of a switching apparatus according to the state of the art; figure 2 is a perspective view of a dolly in a switching apparatus according to the invention; figure 3 illustrates a detail of the actuating devices for mat discharge; figure 4 is a partial side view of a rail on which the dollies roll; figure 5 is a partial sectional view of one of the discharge mats. The apparatus is preferably, but not necessarily, of the closed circuit type that develops along a vertical plane with an outward path and a return path, said paths being interconnected by curved tracts and exhibiting for example the pattern shown in figure 1, which is a representation of a machine according to the state of the art as disclosed in EP-A-611713. The path consists of rails or guides along which by means of chains or another known system a plurality of dollies of the kind shown in figure 2 are dragged, each dolly being provided with a rotating mat, shown in figure 1, that forms the transportation and discharge plane for the objects. The dolly comprises a framework 2 that is provided with pins or arms 3 which in turn are connected to chains (not shown) that drag the dollies, idle mat support rollers 4 supporting the mat 1 being mounted on said framework 2. The pins 3 are hinged to the chains, thereby allowing the dolly to rotate around the axis of the same. On the shafts of mat support rollers 4 the same number of gear wheels 5 are fit, said gear wheels 5 matching in turn with gear wheels 6 that are mounted on pins 7 on which also idle dolly support rollers 8 or the like are mounted. The dolly support rollers 8 lean on the guides or rails that form the path, one of which is illustrated in the figure 4, generally indicated with numeral 9. This guide, that can be seen better in figure 4, has an upper wing 10 that forms a support or roll plane for dolly support rollers 8 and a groove or guide 11, approximately at half height, that runs in parallel with wing 10, at a short distance therefrom. The guide 11 has, at the beginning of the path, a first lenght 12 immediately below wing 10 that thereafter is bent downwards and continues at a lower height for the rest of the path. Guide 11 also has a linking tract 13 that is opened towards the upper part of the guide. At the opposite end, guide 11 is again bent upwards and goes on with a length 15 at the same level as the beginning length 12. Under guide 11, in correspondence with each of the collection devices, as many racks 16 are arranged, only one of which is visible in figures 3 and 4, said racks being subject to the action of pistons 17 that move them from a retracted or disengagement position to a position in which they meddle with the path of the gear wheels 6 that, upon advancement of the dolly, engage in the toothing of the rack and are caused to rotate. In figure 3 both of these positions of rack 16 are illustrated. The mats 1 (see figure 5) consists of a flexible material belt to which a pair of containment tabs 18 are welded, said containment tabs preventing possible transported objects from slipping off the mat in advance of the discharge time. The tabs 18 form an enlargement 19 that protrudes a short length from the inner surface of the mat and are arranged in such a way that in the resting position, as shown in figure 5, they are close to a vertical plane that is perpendicular to the plane defined by the two axes of the mat support rollers 4 but displaced a short distance inwards. The length of belt 1 is such that it is always sufficiently taut, thereby appling a pulling force between the rollers. Owing to this pattern, when the belt stops in a different position from that shown in figure, the enlargement 19 causes the belt of the support rollers to be driven away, thereby causing it to be elastically stretchted for a short distance. This builds up a greater tension in belt 1 which acts by causing a light rotation of the mat to bring it to the resting position shown, in which the enlargement 19 of the tabs no longer engages the surfaces of mat support rollers 4. The apparatus works as follows: the dollies come from the introduction and loading area for the objects to be switched along the guide part 12 (position I of figure 4). Each dolly is provided with three support points, said support points consisting of the dolly rollers support 8 that roll along the guide and of the pin 3 that restrains them to the dragging chains. The front roller passes the entrance of the lower guide length 11 while the dolly is kept in an horizontal position, as it is prevented from rotating around pin 3 by the walls of guide 12 that engage the back dolly support roller 8. When this other roller comes to the entrance of the lower guide part 11, the front roller begins the ascending length 13, thereby tilting the dolly that rotates around pin 3 (position II), said dolly reaching then the transportation position 3, said position being maintained along the whole straigth path length, with the front roller leaning on wing 10 and the lower one rolling along groove 11. During this phase, the tabs 18 prevent the object on mat 3 from slipping off due to the gradient thereof. Upon discharge, the piston 17 is actuated, which moves rack 16 to bring it in corrispondence with the path of the gear wheels 6. Said gear wheels, in their advancement, engage the toothing of the rack and are caused to rotate, thereby transmitting their motion to mat support roller 4 and mat 1. The diameter of the gear wheel 6 will determine, as a function of the dolly speed, the mat discharge speed. Rack 16 is preferably mounted onto the related support with the possibility of moving a short length along its own axes in contrast to the elastic means. For example, rack 16 can comprise slots 20 in which as many pins 21 are inserted, said pins being solidly connected to the support means (not shown), and will have the possibility of moving relative to said pins 20 in contrast to springs or the like. This will allow the rack to better take up the impact with the gear wheel 6. The length of the rack is such that mat 1 is caused to make a rotation that is sufficient to bring it to the starting position, with tabs 18 aligned, as shown in figure 4. Should for any reason the belt stop in a slightly biased position, for example in the position shown with a broken line in figure 5, the mat tension due to the greater extention caused by the presence of anlargement 19 leaning on roller 4 is enough to bring it again to the provided position, centering it again on the roller.

Claims: A switching machine comprising a plurality of dollies each provided with a rotating mat (1) forming a transportation and discharging plane for objects to be sorted said dollies being dragged along a fixed path, characterized in that it further comprises means (8,9) suited to keep the dollies in a tilted position during the displacement. A switching machine as claimed in claim 1, characterized in that each dolly is hinged at a central point and is provided with a pair of idle dolly support rollers (8), said dolly support rollers (8) rolling along a double guide (9) that comprises two superposed lengths (10,11), means (13) suited to direct the front roller (8) towards one (10) of these superposed lengths and the back roller (8) towards the other one (11) being provided, so as to keep the dollies in a tilted position during the transportation. A switching machine as claimed in claim 2, characterized in that said double guide (9) at the starting position exhibits a common length that is limited upwardly and downwardly by parallel waits, said guide presenting an entrance directed towards the lower part (11) of the path and an ascending length (13) directed towards the upper part (10) of the path, the distance between said entrance and said ascending length being the same as the distance between the two idle support rollers (8) on the dolly, said dolly being hinged to a support pin (3) that is arranged in a central position between said rollers. A switching machine according to the proceeding claims, characterized in that gear wheels are provided on the outside of the dolly, said gear wheels (6) being mounted on pins (7) on which also dolly support rollers (8) are mounted, racks (16) being provided level with the object discharge areas, said racks being mounted on movable supports that are suited to bring them from a position in which they do not meddle with the dolly path to a position in which they engage said gear wheels, thereby causing the mat (1) to rotate. A switching machine as claimed in claim 4, in which said racks (16) are mounted on the related supports with the possibility of moving a short length in contrast to elastic means. A switching machine according to the preceeding claims, characterized in that said mats have pairs of containment tabs that form front walls (18), said front walls being suited to prevent the transported objects from slipping off the mat, said tabs presenting, on the inner surface of the mat, a protruding part (19) that is suited to cause the mat to be elastically stretched a short length when it leans onto the related roller, said pairs of tabs being arranged level to each roller, lightly offset so that said protruding parts do not engage the roller when the mat is at rest.

Inventors: FAURE ANDREA ING, GENNARI NEDO ING, FAURE, ANDREA, ING., GENNARI, NEDO, ING.
Applicants: FINMECCANICA SPA, FINMECCANICA S.P.A.
Application year: 1996
Main classification: B07C3
IPC codes: B65H29, B07C5, B65G17, B07C3