ITTO20131048A1 - DEVICE AND UNLOADING METHOD TO ALLOW THE DISCHARGE OF ONE OR MORE ARTICLES AT A TIME FROM A ROW OF ARTICLES ON A SHELF - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"DEVICE AND METHOD OF UNLOADING TO ALLOW THE UNLOADING OF ONE OR MORE ITEMS AT A TIME FROM A ROW OF ITEMS ARRANGED ON A SHELF"

The present invention relates to an unloading device and method for allowing the unloading of one or more articles at a time from a row of articles arranged on a shelf.

In particular, the items could be drug boxes or sundries boxes.

In the field of automatic warehouses, units for moving articles are known, substantially comprising:

- a loading device adapted to receive the articles to be stored;

- a pick-up device movable in a vertical plane and adapted to pick up an article to make it available to an operator; And

- a magazine formed by a plurality of shelves inclined downwards, proceeding from the loading device to the picking device.

According to a known solution, the shelves are horizontally placed side by side and vertically superimposed and are each provided, at one of its own lower ends, with a fixed stop and a movable actuator.

The stop protrudes from the shelf upwards to form a step, which blocks the items on the shelf itself.

The actuator is arranged at the lower end of the row, and can be moved between:

- a rest position in which it is coplanar with the shelf and therefore does not exert any action on the lower end article; And

- an operating position in which it protrudes from the shelf, lifts the lower end article and allows it to climb over the stop.

When it is necessary to pick up an item from one of the shelves, the picking device is placed in front of a lower end of this shelf and controls the actuator with a button. This actuator moves from the rest position to the operative position.

In this way, the end article thus bypasses the stop and falls on the pick-up device.

This known solution has the drawback that the withdrawal device must necessarily be placed immediately below the shelf from which the article must be removed in order to bring the button to interact with the actuator of the shelf itself.

Therefore, to reach the shelf where the item to be picked up is arranged, the pick-up device must continuously move in the vertical plane.

This makes the picking speed of the article dependent on the time required for the picking device to place itself immediately below the shelf where the article to be picked is arranged.

There is a need in the sector to increase the picking speed of the item from the warehouse.

Patent application CN-A-101486406 describes an unloading device formed by a wheel rotating around an axis, arranged at a lower end of the shelf and provided with a single arm protruding radially from the wheel itself.

The unloading device can be selectively moved by rotating the wheel between:

- a stop position, in which the arm blocks the end article of the shelf row; And

- an unloading position, in which the arm does not block the end article of the shelf row and, therefore, allows this article to be unloaded, by gravity, on the picking device.

The unloading device can be moved from the stop position to the unloading position by rotation in a first direction, and from the unloading position to the stop position by rotation in a second direction, opposite to the first direction.

Consequently, it is necessary to continuously rotate the wheel of the unloading device in the first direction from the stop position to the unloading position, and then in the second direction from the unloading position to the stop position.

This makes the unloading device described in patent application CN-A-101486406 particularly difficult to control, generating the risk that the end article is not properly locked when necessary and can therefore be erroneously unloaded without falling on the withdrawal device.

The industry is advised to have an unloading device that can be easily controlled and able to reduce as much as possible the risk that the end article is mistakenly unloaded without falling on the pickup device.

The object of the present invention is to provide an unloading device to allow the unloading of one or more articles at a time from a row of articles arranged on a shelf, which allows to satisfy at least one of the requirements specified above.

The aforesaid object is achieved by the present invention, since it relates to an unloading device for allowing the unloading of one or more articles at a time from a row of articles arranged on a shelf, as defined in claim 1.

The present invention also relates to an unloading method for allowing the unloading of one or more articles at a time from a row of articles arranged on a shelf, as defined in claim 14.

For a better understanding of the present invention, a preferred embodiment is described below, purely by way of non-limiting example and with reference to the attached figures, in which:

- Figure 1 illustrates, in side view, an article handling unit comprising a plurality of unloading devices made according to the dictates of the present invention;

- Figure 2 illustrates, in front view, the unit for handling items in Figure 1; And

Figures 3 to 7 illustrate, on a particularly enlarged scale, successive operating steps of an unloading device made according to the dictates of the present invention.

With reference to Figures 1 and 2, 1 indicates a handling unit for items 2a, 2b, 2c.

In particular, the articles 2a, 2b, 2c could be boxes of drugs or boxes of various kinds.

Unit 1 is preferably used in an automatic warehouse, even more preferably in an automated pharmacy.

Unit 1 essentially includes:

- a loading device 3 (visible in figure 1) to load unit 1 with items 2a, 2b, 2c to be stored;

- a magazine 4 which can be fed by the loading device 3 with the articles 2a, 2b, 2c and formed by a plurality of shelves 6, 7 defining respective loading surfaces for the articles 2a, 2b, 2c themselves; And

- a withdrawal device 5 suitable for picking up the items 2a, 2b, 2c unloaded from the shelves 6, 7 of the warehouse 4 and conveying them to a user, for example an automated pharmacy shop.

The loading device 3 and the pick-up device 5 are movable parallel to a direction Z, arranged in vertical use, and a direction Y orthogonal to the direction Z and arranged in horizontal use.

In the case illustrated, the loading device 3 and the pick-up device 5 are stacker elevators.

With reference to Figures 3 to 7, the shelves 6, 7 are elongated along an inclined X direction with respect to the Z, Y directions.

In the case illustrated, the X direction is inclined with respect to a horizontal plane.

Each shelf 6, 7 also comprises (Figure 1): - an inlet 9 arranged on the side of the loading device 3; And

- an outlet 10 arranged on the side of the withdrawal device 5.

Each shelf 6, 7 is descending, proceeding from the entrance 9 towards the exit 10, so that the articles 2a, 2b, 2c slide by gravity towards the exit 10.

The shelves 6, 7 form respective rows side by side parallel to each other parallel to the X direction and respective columns overlapping each other parallel to the Z direction.

Shelves 6 are arranged at a greater height than shelves 7.

Each shelf 6, 7 comprises a respective unloading device 15, which is illustrated in Figures 3 to 7.

A row 11 of articles 2a, 2b, 2c is arranged on each shelf 6, 7.

More precisely, the article 2a of each row 11 is arranged at the exit 10 of the respective shelf 6, 7 and defines the lower end of the row 11 itself.

Article 2b of each row 11 is placed immediately adjacent to and at a higher level than article 2a.

Article 2c of each row 11 is placed immediately adjacent to and at a higher level than article 2b.

In the following of the present description reference is made to a single unloading device 15 and to a corresponding shelf 6, 7, since all the unloading devices are identical to each other.

Advantageously, the unloading device 15 comprises an element 20 comprising, in turn, a plurality of vanes 21, 22, 23, three in the case illustrated, and can be selectively displaced between:

- a first stop position (Figure 3), in which the pallet 21 blocks the article 2a at the end of the row and prevents it from unloading from the shelf 6, 7; And

- a second stop position (Figure 7), in which the pallet 21 has freed the article 2b so as to allow it to be unloaded from said shelf, and in which the pallet 22 blocks the article 2b and prevents it from being unloaded from the shelf 6 , 7.

In greater detail, the displacement of the element 20 between the first stop position and the second stop position allows the unloading of the article 2a from the shelf 6, 7.

More precisely, the displacement of the element 20 between the first stop position and the second stop position moves the pallet 21 away from the article 2a, leaving the latter free to fall, under the action of the pressure of the weight of the articles 2b, 2c and / or by gravity, from shelf 6, 7.

In greater detail, in the first stop position of the element 20, the pallet 21 is arranged orthogonally to the X direction and defines a stop surface for the article 2a at the exit 10 of the shelf 6, 7 (Figure 3).

In this first stop position, moreover, the vanes 22, 23 are spaced from the article 2a.

In the second stop position of the element 20 (Figure 7), the pallet 22 is arranged orthogonally to the X direction and defines a stop surface for the article 2b at the exit 10 of the shelf 6, 7.

In this second stop position, moreover, the vanes 21, 22 are spaced from article 2b.

The element 20 can also be moved to a first intermediate position (figure 5), which is interposed between the first stop position and the second stop position and in which the article 2a overrides the vanes 21, 23 and can reach the pickup device 5.

The element 20 is also movable in a third stop position (not shown), in which the pallet 23 blocks the article 2c of the row 11 and prevents it from being unloaded from the shelf 6, 7.

In greater detail, in the third stop position, the pallet 23 is arranged orthogonally to the X direction and defines a stop surface for the article 2c at the exit 10 of the shelf 6, 7.

The element 20 is also movable in a second intermediate position (not shown) interposed between the second position and the third position, and in which the article 2b bypasses the pallets 21, 22 and can reach the picking device 5.

In greater detail, the element 20 is a rotating shaft mounted in an idle way at the exit 10 of the shelf 6, 7 and rotating around an axis A orthogonal to the Z, Y directions and transverse to the X direction.

Axis A is, in the case illustrated, horizontal. The vanes 21, 22, 23 protrude radially from the element 20 and are angularly equidistant to each other around the axis A.

Axis A is arranged on the opposite side of exit 10 with respect to entrance 9.

The overall dimensions of the vanes 21, 22, 23 in the radial direction to the axis A is such that they do not interfere with the shelf 6, 7, but that they are able to prevent the unloading of the article 2a, 2b, 2c when the element 20 it is arranged respectively in the first position, second position and third stop position.

The element 20 can be moved in succession between the first stop position, the first intermediate position, the second stop position, the second intermediate position and the third stop position, by rotation in one direction, clockwise in the case illustrated in the figures from 3 to 7.

The further rotation of the element 20 in the aforementioned single direction starting from the second intermediate position brings the element 20 back to the first stop position.

The displacement of the element 20 from the first stop position (Figure 3) to the first intermediate position (Figure 5) occurs thanks to the pressure due to the weight of the items 2b, 2c of row 11.

Similarly, the movement of the element 20 from the second stop position (Figure 7) to the second intermediate position occurs thanks to the pressure due to the weight of the articles 2b, 2c of row 11.

The unloading device 15 further comprises an actuator 30 adapted to:

- keep the element 20 in the first stop position, second stop position and third stop position;

- allow the movement, under the action of pressure due to the weight of the articles 2b, 2c, of the element 20 from the first stop position to the first intermediate position, and from the second stop position to the second stop position; And

- move the element 20 from the first intermediate position to the second stop position and from the second intermediate position to the third stop position.

In greater detail, the actuator 30 includes:

- a casing 31 arranged at the exit 10 of the shelf 6, 7 and fixed to the shelf 6, 7 itself in a lower position than the shelf 6, 7 itself;

- a solenoid 32 excitable by a direct or alternating current, and arranged in a fixed position with respect to the casing 31;

- a movable drawer 33 inside the casing 31 back and forth parallel to the X direction; And

- a stem 34 movable with respect to the solenoid 32 following the excitation of the latter and interposed between the solenoid 32 and the drawer 33.

The drawer 33 defines a groove 36 open orthogonally to the X direction towards the shelf 6, 7 and delimited parallel to the X direction between two walls 37, 38 opposite each other along the same X direction.

The wall 37 is arranged on the side of the stem 34 while the wall 38 is arranged on the opposite side of the stem 34 and, therefore, opposite the wall 37 with respect to the axis B.

The walls 37, 38 are connected to each other by a wall 39 parallel to the X direction and which delimits the groove 34 on the opposite side of the shelf 6, 7.

The wall 37 is orthogonal to the wall 39. The wall 38 is inclined with respect to the wall 39 and moves away from the wall 39, proceeding from the opposite side of the stem 34.

The drawer 33 also defines, on the opposite side of the groove 36 with respect to the wall 37, a wall 40 parallel to the shelf 6, 7.

Under the action of the solenoid 32, the drawer 33 is movable along the X direction and with respect to the exit 10 of the shelf 6, 7 between:

- a rearward position (Figures 3 and 7), in which one (the blade 22 in Figure 3 and the blade 23 in Figure 7) of the blades 21, 22, 23 abuts against the wall 40; And

- an advanced position (Figure 5), in which the aforesaid one (the blade 22 in Figure 5) of the blades 21, 22, 23 abuts against the wall 37 and engages the groove 36.

When the drawer 33 is in the retracted position, the wall 40 holds in a fixed position one (the pallet 22 in Figure 3 and the pallet 23 in Figure 7) of the pallets 21, 22, 23.

It follows that when the drawer 33 is in the back position, the rotation of the element 20 around the axis A is prevented.

Consequently, the drawer 33, when placed in the retracted position, blocks the element 20 in the first stop position (Figure 3), in the second stop position (Figure 7) or in the third stop position.

Moving the drawer 33 from the rear position to the advanced position (Figures 4 and 5) frees the pallet 22 and allows the rotation, under the action of the pressure of the weight of the articles 2a, 2b, 2c of the element 20.

When the drawer 33 is in the advanced position, the element 20 has rotated around the axis A until the pallet 22 abuts against the wall 37 (Figure 5).

In this condition, the vanes 21, 23 are bypassed by article 2a.

In this way, when the drawer 33 is in the advanced position, the element 20 is in the first intermediate position or in the second intermediate position.

Subsequently, moving drawer 33 back to the rear position causes:

- first the sliding of the wall 39 with respect to the blade 22 parallel to the direction X until the blade 22 contacts the wall 38 (Figure 6); and - then rotate the clockwise rotation of element 20 clockwise until the vane 22 stops in article 2b (Figure 7).

The actuator 30 also comprises a spring 45 interposed between the casing 31 and the drawer 33 and adapted to pre-load the drawer 33 towards the rear position.

The unit 1 also comprises a control unit 50 (only schematically illustrated in Figures 1 and 2), which controls the actuator 30 to move the drawer 33 between the forward and backward positions and controls the pick-up device 5 in the plane defined by the Y, Z axes.

The control unit 50 is also configured, on the basis of a withdrawal request of article 2a, 2b, 2c arranged on shelf 6, for:

- arranging the pick-up device 5 below the shelf 6; And

- rotate the element 20 from the first stop position to the second stop position, in order to determine the unloading of the article 2a from the shelf 6 on the pick-up device 5.

It is important to emphasize that the control unit 50 is not configured to arrange the picking device 5 necessarily at the exit 10 of the shelf 6 from which article 2a must be unloaded.

Otherwise, the control unit 50 has in memory a safety height corresponding to the height from which the article 2a can fall without being damaged and is configured to arrange the pick-up device 5 below the shelf 6 and at a distance along the Z direction equal to the aforementioned safety height.

For example, the control unit 50 could arrange the pick-up device 5 in correspondence with the shelf 7 and command, through the element 20, the unloading of the article 2a from the shelf 6, arranged at a higher level than the shelf 7.

The operation of the unloading device 15 is described with reference to a single shelf 6 and a single row 11 of articles 2a, 2b, 2c. The operation of the unloading device 15 is also described starting from a configuration (illustrated in Figure 3) in which the article 2a is arranged in correspondence with the outlet 10 of the shelf 6 and the articles 2b, 2c are arranged immediately adjacent to the respective articles 2a, 2b. The operation of the unloading device 15 is finally described starting in which the element 20 is in the first stop position, the drawer 33 is in the retracted position, the pallet 21 blocks the article 2a, 2b, 2c and the pallet 22 is blocked by the wall 40 of the drawer 33 itself.

In order to unload article 2a from shelf 6, the control unit 50 moves the drawer 33 to the forward position along the B axis (Figures 4 and 5).

More specifically, the control unit 50 operates the solenoid 32. The magnetic field created by the solenoid 32 causes the rod 34 and the drawer 33 to move along the axis B and so as to move the drawer 33 away from the outlet 10 of the shelf 6, 7.

The displacement of the drawer 33 in the forward position disengages the pallet 22 from the wall 40. Consequently, the element 20 rotates clockwise under the action of the weight of the articles 2a, 2b, 2c, up to the first intermediate position (Figure 5) and the article 2a can slide on the shelf 6 beyond the exit 10. Consequently, the article 2b slides, by gravity, on the shelf 6 until it reaches the exit 10.

In this intermediate position, the pallet 22 is in abutment against the wall 37 of the drawer 33 and the article 2a is partly resting on the shelf 6 and partly resting on the pallets 23, 21.

At this point, the control unit 50 moves the drawer 33 back along the B axis from the forward position to the back position (Figures 6 and 7).

In greater detail, the control unit 50 electrically supplies the solenoid 32, so that the latter creates a magnetic field generating a force on the rod 34 directed along the axis B and tending to bring the rod 34 closer to the shelf 6. Consequently , the stem 34 and the drawer 33 slide along the axis B and approach the outlet 10 of the shelf 6.

The movement of the drawer 33 from the forward position to the back position is facilitated by the elastic action of the spring 45.

The displacement of the drawer 33 from the forward position to the rear position first causes the groove 36 to slide with respect to the pallet 22 until the pallet 22 abuts against the wall 38 of the drawer 33 itself (Figure 6).

This causes a slight rotation (clockwise in Figures 3 to 7) of the element 20, which guides the article 2a resting on the vanes 21, 23 beyond the element 20 itself. The article 2a can thus, by gravity, fall on the withdrawal device 5 (Figure 6).

The further advancement of the drawer 33 towards the advanced position causes, thanks to the thrust action of the surface 38 on the pallet 22, the further rotation of the element 20 clockwise until reaching the second stop position (Figure 7).

In this second stop position, the pallet 22 blocks the article 2b, which has slipped on the shelf 6 until it reaches the exit 10, after the article 2a has been unloaded.

The element 20 is also blocked in the second stop position by the wall 40 of the drawer 33. This wall 40, in fact, stops the pallet 23, preventing the rotation of the element 20 under the action of the pressure due to the weight of the articles 2b, 2c.

If it is necessary to unload the article 2b, it is sufficient for the control unit 50 to bring the drawer 33 back to the forward position, so as to disengage the pallet 22 from the article 2b and then to the rear position, in order to reach the third stop position (not shown), in which the pallet 23 stops the article 2c.

The control unit 50 also moves the pickup device 5 to a lower position than the shelf 6 and at a distance, measured parallel to the Z direction, lower than the safety height.

In this way, the pick-up device 5 collects the articles 2a, 2b, 2c unloaded from the shelf 6 through the unloading device 15.

It is important to underline that the pick-up device 5 does not necessarily have to be arranged immediately below the outlet 10 of the shelf 6, but could be arranged well below along the Z direction, for example immediately below the outlet 10 of the shelf. shelf 7.

From an examination of the discharge device 15 and of the method implemented according to the present invention, the advantages it allows to obtain are evident.

In particular, the element 30 is movable between the first stop position in which the pallet 21 stops the article 2a, and the second stop position in which the pallet 21 has released the article 2a and the pallet 22 stops the article 2b.

Consequently, it is possible to allow the unloading of items 2a, 2b, 2c of row 11 simply by rotating the element 20 in one direction from the first stop position (Figure 3) to the second stop position (Figure 7).

It follows that the discharge device 15 is easier to control and more reliable than the discharge devices of the known type and described in the introductory part of the present description.

The drawer 33 allows you to easily control the movement of the member 20 between the first, second and third stop positions.

In greater detail, when the element 20 is in the first stop position and the drawer 33 is in the rear position, the wall 40 blocks the pallet 22, preventing the rotation of the element 20 (Figure 3).

When the drawer 33 is placed in the forward position, the wall 40 no longer holds the blade 22, allowing the rotation of the element 20 in the first direction, until the blade 22 hits the wall 37 (Figure 5). Moving the drawer 33 to the rear position determines the further rotation of the element 20 in the first direction, up to the second stop position (Figure 7), in which the pallet 22 blocks the article 2b.

The control unit 50 is configured to memorize a safety height and to arrange the pick-up device 5 below the shelf 6 from which to unload the article 2a, 2b, 2c and at a distance less than or equal to the height of safety.

It follows that the withdrawal device 5 does not necessarily have to be placed adjacent to the outlet 10 of the filling 6 from which to download the article 2a, 2b, 2c. but it can be arranged under the shelf 6 itself and receive the articles 2a, 2b, 2c unloaded from different shelves 6, 7.

Therefore, the number of movements that the pick-up device 5 must perform to unload a given number of articles 2a, 2b, 2c is dramatically reduced with respect to the known solutions and described in the introductory part of the present description.

It is thus possible to increase the picking speed of the articles 2a, 2b, 2c from the warehouse 4.

Finally, it is clear that modifications and variations can be made to the unloading device 15 and to the previously described and illustrated method without thereby departing from the scope of protection of the present invention.

In particular, the element 20 could include only two vanes 21, 22 (21, 23 or 22, 23) or a number of vanes greater than three.

The shelves 6, 7 could also be arranged on a horizontal plane. In this case, the shelves 6, 7 would comprise actuation devices such as conveyors or springs to advance the articles 2a, 2b, 2c along the horizontal direction X in this case.

Claims (1)

CLAIMS 1.- Unloading device (15) to allow the unloading of one or more articles (2a, 2b, 2c) at a time from a row (11) of articles (2a, 2b, 2c) arranged on a shelf (5, 6 ), characterized in that it comprises an element (20) comprising, in turn, a first blade (21) and at least a second blade (22); said element (20) being, moreover, selectively movable between: - a first stop position, in which the said first pallet (21) stops a first end article (2a) of the said row and prevents its unloading from the said shelf (6, 7); And - a second stop position, in which the said first blade (21) has freed the said article (2a, 2b, 2c) so as to allow it to be unloaded from the said shelf (6, 7), and in which the said second blade ( 22) stops a second article (2b) adjacent to said first article (2a) and prevents its unloading from said shelf (6, 7). 2.- Device according to Claim 1, characterized in that the displacement of said element (20) from said first stop position to said second stop position causes, in use, the disengagement of said first blade (21) from said first article (2a). 3.- Device according to Claim 1 or 2, characterized in that said element (20) is rotatable around a first axis (A) transversal to an extension direction (X) of said shelf (6, 7) and from which the said first and at least second blades (21, 22) project radially in cantilever fashion; said element (20) being displaceable from said first stop position to said second stop position and, subsequently, from said second stop position to said first stop position through a rotation around said axis (A) and in one direction only of rotation. 4.- Device according to any one of the preceding claims, characterized in that at least said first blade (21) can be overridden by said first article (2a), when said element (20) moves, in use, between said first and second stop positions. 5.- Device according to any one of the preceding claims, characterized in that said element (20) comprises a third blade (23) interposed between said first and second blades (21, 22); the said third blade (23) being spaced from the said first article (2a), when the said element (20) is arranged in the said first and second stop positions, and when the said element (20) moves between the said first and second stop position so as not to interfere with said first article (2a); said element (20) being movable by said rotation in the only said direction from said second stop position to a third stop position and from said third stop position to said first stop position; said third blade (23) contacting a third article (2c) consecutive to said second article (2b) and preventing it from sliding on said shelf, when said element (20) is arranged in said third stop position. 6.- Device according to any one of claims 2 to 5, characterized by the fact that said axis (A) is fixed, and by the fact that it comprises a drawer (33) movable along a second axis (B) transversal to said first axis (A) between: - a rearward position, in which the said drawer (33) blocks one (21) of the said vanes (21, 22, 23) against the corresponding said first or second article (2a, 2b), so as to prevent unloading of the corresponding said first or second article (2a, 2b); And - an advanced position, in which another (22) between said first or second blade (21, 22, 23) engages a groove (36) of said drawer (33). 7.- Device according to Claim 6, characterized in that the said drawer (33) is movable along a forward stroke described from the said backward position to the said forward position, and a return stroke described from the said second forward position to the said backward position; said forward stroke of said drawer (33) allowing, in use, the displacement of said element (20) from said first stop position to an intermediate position between said first stop position and second stop position; said return stroke of said drawer (33) causing, in use, the displacement of said element (20) towards said second stop position. 8.- Device according to Claim 7, characterized in that the said drawer (33) comprises: - a stop (40), which contacts and blocks said other (22) between said vanes (21, 22, 23) when said drawer (33) is in said retracted position, so as to lock said element (20 ) in said first stop position; And - a groove (36) extending at a greater distance from said first axis (A) with respect to said stop (40), which houses said other (22) between said vanes (21, 22, 23) when said drawer ( 33) is in the said advanced position; the said groove (36) being arranged upstream of the said stop (40), proceeding along the said second axis (B) according to the direction oriented from the said retracted position to the said advanced position of the said drawer (33). 9. A device according to Claim 8, characterized in that the said drawer (33) comprises, proceeding along the said second axis (B) according to the direction oriented from the said backward position to the said forward position: - a first wall (37) transversal to said second axis (B); - said groove (36); And - a second wall (38) opposite to said first wall (37) and transversal to said second axis (B). 10.- Device according to any one of claims 6 to 9, characterized in that it comprises: - an actuator (30, 32) which can be activated to move said drawer (33) between said first position and second position; And - elastic means (45) interposed between a fixed part of said device and said drawer (33), and preloaded so as to elastically load said drawer (33) towards one of said first and second positions. 11.- Device according to Claim 10, characterized in that said actuator (30, 32) comprises: - a solenoid (32) excitable so as to generate a magnetic field; And - a rod (34) sliding with respect to the said solenoid (32) along the said second axis (B) following the excitation of the said solenoid (33) and coupled with the said drawer (33). 12.- Device according to any one of claims 6 to 11, characterized in that it comprises a casing (31) which can be fixed to said shelf (6, 7) and accommodates said drawer (33) in a movable manner with respect to said second axis ( B). 13.- Item handling unit (2a, 2b 2c) comprising: - a plurality of shelves (6, 7) defining respective outlets (10) for said articles (2a, 2b, 2c) to be unloaded; - a plurality of unloading devices (15) according to any one of the preceding claims and each fixed to a respective shelf (6, 7); - a withdrawal device (5) adapted to receive said article (2a, 2b, 2c) unloaded; And - a control unit (50) configured for: i) memorize a maximum safety height corresponding to the maximum height from which the said article (2a, 2b, 2c) can fall without being damaged; ii) arranging the said pick-up device (5) below the said shelf (6, 7) and at a distance less than or equal to the said safety height; And iii) moving said element (20) of said unloading device (1) associated with shelf (6, 7) from which said article (2a, 2b, 2c) is to be unloaded from said first stop position to said second position stop. 14.- Method of unloading one or more articles (2a, 2b, 2c) at a time from a row (11) of articles (2a, 2b, 2c) arranged on a shelf (6, 7), characterized by the fact of comprising step i) of moving a first element (20) provided with a first blade and a second blade (21, 22, 23) between: - a first position, in which the said first pallet (21) blocks a said first end article (2a) of the said row (11) and prevents its unloading from the said shelf (6, 7); And - a second position, in which said first pallet (21) has freed said article (2a, 2b, 2c) so as to allow it to be unloaded from said shelf (6, 7) and in which said second pallet (22) contacts a further second article (2b) adjacent to said first article (2a) and prevents its unloading from said shelf (7). 15.- Method according to claim 14, characterized in that said step i) comprises step ii) of making said first article (2a) bypass said first blade (21) and a third blade (23) of said element (20), when said element (20) moves from said first stop position to said second stop position. 16.- Method according to claim 14 or 15, characterized that said step i) comprises step iii) of rotating said element (20) around a first axis (A) and in a single direction to cause the displacement of said first element (20) first from said first position to said second position and then from said second stop position to said first stop position. 17. Method according to any one of claims 14 to 16, characterized in that it comprises the steps of: iv) memorize a maximum safety height corresponding to the maximum height from which the said article (2a, 2b, 2c) can fall without being damaged; v) arranging the said pick-up device (5) below the said shelf (6, 7) and at a distance less than or equal to the said safety height; And vi) moving said element (20) of said unloading device (1) associated with shelf (6, 7) from which said article (2a, 2b, 2c) is to be unloaded from said first position to said second position.