WO2018172892A1

WO2018172892A1 - Stacker crane for warehouses

Info

Publication number: WO2018172892A1
Application number: PCT/IB2018/051763
Authority: WO
Inventors: Marco Camelli
Original assignee: Jbc S.R.L.
Priority date: 2017-03-22
Filing date: 2018-03-16
Publication date: 2018-09-27
Also published as: IT201700031492A1; EP3601143A1

Abstract

Stacker crane (1) for automatic warehouses is disclosed that is suitable for moving rapidly packages with low stability or consistency, in which a load is carried on a fork supporting surface (2), a constant velocity joint of the type with balls connects the supporting surface to an articulated arm (15) that is movable along at least one horizontal controlled axis, a linear actuator (22) enables the tilt to be modified of the supporting surface around the joint with respect to a horizontal position.

Description

Stacker Crane for Warehouses

Background of the invention

[0001] The invention relates to a stacker crane, which is usable in particular for handling packages in automatic warehouses.

[0002] Specifically, but not exclusively, the invention can be applied in automatic warehouses for packages with low stability or consistency, for example warehouses for laundries, assembly lines, forwarders, food picking, etc.

[0003] Innumerable examples are known of automatic warehouses provided with stacker cranes, for example stacker cranes with forks for handling pallets, boxes or trays, stacker cranes with forks provided with supporting surfaces with ridges or grooves that enable forks to be inserted underneath the package to be lifted, stacker cranes with arms provided with orthogonal Cartesian movements on slides, stacker cranes with simple or complex articulated arms with interpolated movements, stacker cranes with articulated and interpolated arms with sensors (for example optical sensors) to centre with precision the grooves of the shelves and/or the openings of the pallets, robots travelling on rails parallel to the shelves and provided with articulated arms with various controlled axes and provided with forks/grippers at the end, etc.

[0004] Patent publications JP 2001240213 A and JP 2007297189 A show stacker cranes with systems for compensating for the load inertia.

[0005] Patent publication DE 3739136 Al shows a stacker crane with an oscillating horizontal arm and a system for retaining the pack constantly parallel to the original position thereof during the movement of the arm.

[0006] Patent publication DE 19518618 Al shows a stacker crane with a fork with an articulated system with two arms hinged together.

[0007] Patent publication EP 0322539 Al shows a stacker crane with a system for retaining the pack with suction cups.

[0008] Patent publication DE 9413114 Ul shows a stacker crane suitable for warehouses with cantilever shelving, in which the fork with several tines of the stacker crane couples with the slatted plane of the shelving.

[0009] Patent publication GB 1124901 A shows a monorail stacker crane with orientable forks.

[0010] Patent publication US 5174454 A shows a stacker crane with a conveying table formed by sliding belts. [0011] Patent publication WO 03/019425 Al shows a stacker crane for warehouses with a lateral gripping system for gripping the packs.

[0012] One of the problems of the prior art is to move quickly a particularly unstable load, for example a free load not provided with a support or container (a pallet, a box or an auxiliary tray), maintaining the stability of the load itself. At times, in fact, especially for simply resting packages, it is necessary to adopt limited speeds and accelerations to avoid losing the load.

Summary of the invention

[0013] One object of the invention is to make a stacker crane that is able to solve the aforesaid problem of the prior art.

[0014] One advantage is to provide a stacker crane that is suitable for handling fast and safely packages with low stability.

[0015] One advantage is to permit handling of both free packages, and of packages placed on a support or a container (for example pallet).

[0016] One advantage is to handle a load safely and effectively without the need to hold the load with specific gripping means (for example with grippers or other temporary retaining systems).

[0017] One advantage is to handle rapidly free packages of low consistency, that cannot be held (for example packages that have to be taken from below by a fork or a pallet), without risk of losing the load.

[0018] One advantage is to make available a stacker crane with a movable plane for supporting the load that can work as a cantilever at great lateral depth without stressing excessively the support structure of the plane.

[0019] One advantage is to reduce the stress and deformation of the support structure, in particular of the column on which the slide can slide that supports the articulated arm that in turn supports the supporting surface of the load.

[0020] One advantage is to provide a stacker crane for warehouses that is constructionally simple and cheap.

[0021] These objects and advantages, and yet others, are reached by a stacker crane according to one or more of the claims set out below.

[0022] In one embodiment, a stacker crane comprises a movement system with one or more controlled axes, a (flat) supporting surface connected to the movement system by a connection joint that permits tilt variations of the (flat) supporting surface with respect to a horizontal plane (for example a constant velocity joint, in particular of the ball or double Cardan joint type), an actuator for varying the tilt of the (flat) supporting surface around the connection joint so that the (flat) supporting surface, whilst it moves in a horizontal direction, is tilted forwards during the acceleration step and backwards during the deceleration step, so as to balance the inertia force applied to the load and maintain the stability of the load even at great acceleration.

[0023] In one embodiment, an automatic warehouse is provided with at least one stacker crane that comprises a (flat) supporting surface of the load that can be tilted (at the command of an actuator) around a connection joint so as to compensate for the inertia forces that act on the load in the acceleration and deceleration steps and/or so as to compensate for aerodynamic resistance.

Brief description of the drawings

[0024] The invention can be better understood and implemented with reference to the attached drawings that illustrate some embodiments thereof by way of non-limiting examples, in which:

figure 1 is a perspective view of a first embodiment of a stacker crane made according to the invention;

figure 2 is a view in another perspective of the stacker crane of figure 1 ;

figure 3 is a top view of a detail of the stacker crane of figure 1 that includes the articulated arm and the fork supporting surface;

figure 4 is a perspective view of the detail of figure 3;

figure 5 is a partially sectioned vertical raised side view of the detail of figure 3, with an enlarged detail;

figure 6 shows the detail of figure 5 in an operating configuration in which the supporting surface is tilted backwards;

figure 7 shows the detail of figure 5 in an operating configuration in which the supporting surface is tilted forwards;

figure 8 is a vertical raised view of the articulated arm and of the supporting surface in a configuration tilted forwards;

figure 9 is the view of figure 8 in a horizontal configuration;

figure 10 is the view of figure 8 in a configuration tilted backwards;

figure 11 is a perspective view of a detail of a second embodiment of a stacker crane made according to the invention; figure 12 shows two different operating configurations of a stacker crane made according to the invention, in which the supporting surface is, on the left, in a transferring position (outside the shelving of the warehouse) and, on the right, in a loading/unloading position (inside the shelving of the warehouse);

figure 13 shows, with top plan views, three steps in sequence in which the supporting surface moves from the transferring position to the loading/unloading position;

figure 14 shows, with vertical raised side views, three operating configurations that the supporting surface can adopt, through the effect of the drive of the linear actuator, when it is in the loading/unloading position;

figure 15 is a top plan view of the stacker crane of figure 1 between two sets of shelving arranged opposite one another;

figure 16 is a diagram that shows five steps in sequence of the movements performed by the arm of the stacker crane of figure 15 to rotate the supporting surface from one set of shelving to the other;

figure 17 is a perspective view of a third embodiment of a stacker crane made according to the invention.

Detailed description

[0025] For greater clarity and simplicity of exposition, analogous elements of different embodiments have been indicated by the same numbering.

[0026] With reference to the aforesaid figures, with 1 a stacker crane for an automatic warehouse has been indicated overall. The stacker crane 1 comprises a movement system (with one or more controlled axes) and at least one supporting surface 2 for a load moved by the movement system. In particular, the supporting surface 2 may comprise a resting surface of flat or almost flat shape.

[0027] The supporting surface 2 is rotatably coupled with the movement system around a first (vertical) rotation axis A, as will be explained better below. The supporting surface 2 may comprise, as in this embodiment, a fork 33 with several tines that are parallel to one another. The upper surface of the tines may have a surface with great adhesion to retain a moving package C more effectively.

[0028] The movement system comprises at least one first controlled axis of linear movement (in a horizontal direction). In particular, the movement system comprises at least one first column 3 extending in a vertical and movable direction in a horizontal direction F along the first controlled movement axis. The first column 3 is coupled with at least one (horizontal) linear guide, in particular with a lower guide 4 and with an upper guide 5.

[0029] The horizontal movement is controlled by a first motor 6. The first motor 6 is mounted on the first column 3. A rotor of the first motor 6 is connected to at least one pinion coupled with at least one rack. In particular, the rotor of the first motor 6 is connected to an upper pinion 7 coupled with an upper rack 8 (parallel and adjacent to the linear upper guide 5) and to a lower pinion 9 coupled with a lower rack 10 (parallel and adjacent to the lower linear guide 4).

[0030] The movement system comprises a movable support 11 (a carriage, as in this embodiment, or a slide or another type of movable support) on the first column 3 in a vertical direction along a second controlled axis of (vertical) linear movement. The movable support 11 is coupled with a (vertical) linear guide 12 fixed to the first column 3. The vertical movement of the movable support 11 is controlled by a second motor 13. The second motor 13 is mounted on the first column 3. The movable support 11 is fixed to a flexible member 14 (for example a toothed belt) wound in a closed loop (that is slidable on pulleys). A rotor of the second motor 13 controls the sliding of the flexible member 14 and thus the vertical movement of the movable support 11 carried by the flexible member 14.

[0031] The movement system comprises an articulated arm 15 rotatably coupled with the movable support 11 (carriage) around a second (vertical) rotation axis B parallel to the first rotation axis A. The rotation of the arm 15 around the second rotation axis is controlled by a third motor 16 (mounted on the movable support 11). The supporting surface 2 (in this case of the fork type) is rotatably coupled with the aforesaid arm 15 around the first rotation axis A. The movement system of the supporting surface 2 may accordingly comprise, as in this embodiment, at least three controlled axes of which at least two are linear axes (horizontal movements on guides 4 and 5 and vertical movements on the guide 12) and at least one rotational axis (movements on a horizontal plane around the second rotation axis). The first rotation axis is far from the second rotation axis, so the arm 15 extends along a (horizontal) longitudinal axis passing through the first rotation axis and the second rotation axis.

[0032] The rotating arm 15 may adopt (rotating around the second rotation axis B) at least one transferring position - see figures 1-10, 12 (on the left), 13 (on the left), 15 and 17 - in which the longitudinal axis thereof is parallel to the aforesaid horizontal movement direction F or almost parallel to this direction, for example tilted with respect to the horizontal movement direction F with a tilt angle comprised within a + 5°, or + 10°, or + 15°, or + 20° range. The drive element is configured in such a manner as to tilt forwards or backwards the supporting surface 2 when the arm 15 is in the aforesaid transferring position.

[0033] The rotating arm 15 may adopt (rotating around the second rotation axis B) at least one loading/unloading position - see figures 11, 12 (on the right), 13 (on the right), 14 and 16 (on the right) - in which it is perpendicular to a vertical plane that passes for the aforesaid horizontal movement direction F, or almost perpendicular to this vertical plane, for example tilted with respect to the perpendicular to this vertical plane with a tilt angle comprised within a range of + 5°, or + 10°, or + 15°, or + 20°.

[0034] A connection joint 17 is interposed between the supporting surface 2 and the movement system. In particular, the connection joint 17 is interposed between the supporting surface 2 and the movable (rotating) arm 15 on the horizontal plane.

[0035] The connection joint 17 may be configured, in particular, to enable the supporting surface 2 to rotate around two or more rotation axes. The connection joint 17 may comprise, in particular, a constant velocity joint, for example a constant velocity joint of the type with non-sliding balls. In other embodiments the connection joint may comprise another type of constant velocity joint, for example a double Cardan joint. In particular the connection joint may be capable of transmitting torque and having a fixed axial position. In other embodiments the connection joint may comprise a joint that is not a constant velocity joint, for example a simple Cardan joint, or an elastic joint. The connection joint may comprise a joint (in particular a mechanical joint) that is able to transmit torque between at least two elements and to enable the two elements coupled by the joint to perform tilts in relation to one another. The connection joint may permit, in particular, tilts in more directions, for example in all directions at 360°. The connection joint may permit, in particular, tilts of at least 10°, or at least 15°, or at least 20°.

[0036] The connection joint 17 is configured in such a manner as to enable the supporting surface 2 to be tiltable with respect to a horizontal plane. In particular, the supporting surface 2 may adopt, by movements around the connection joint 17, at least one horizontal position (figures 5 and 9, with reference to the aforesaid transferring position; figure 14 in the centre, with reference to the aforesaid loading/unloading position), at least one position tilted forwards (figures 7 and 8, with reference to the aforesaid transferring position; bottom of figure 14, with reference to aforesaid loading/unloading position) and at least one tilted backwards position (figures 6 and 10, with reference to the aforesaid transferring position; top of figure 14, with reference to the aforesaid loading/unloading position).

[0037] When the arm 15 is in the transferring position, the terms "forwards" and "backwards" refer to a movement of the supporting surface 2 in a horizontal movement direction F. Substantially, "forwards" means that a front edge of the supporting surface 2 is lower than the horizontal position (figure 8), whereas "backwards" means that the aforesaid front edge is higher than the horizontal position (figure 10).

[0038] When the arm 15 is in the loading/unloading position, the terms "forwards" and "backwards" refer a position of the distal end of the supporting surface 2. This distal end substantially coincides with the front edge, i.e. with the end more cantilevered and further from the coupling zone of the joint 17, so that, substantially, "forwards" means that the distal end (or front edge) of the supporting surface 2 is lower (bottom of figure 14) than the horizontal position (centre of figure 14), whereas "backwards" means that the aforesaid distal end (or front edge) is higher (top of figure 14) than the horizontal position.

[0039] The connection joint 17 may comprise, as in these embodiments, a hollow outer body 18 (tubular, in particular with a cylindrical outer surface) coupled rotatably (in particular by at least one rolling support, for example a pair of ball bearings) with the arm 15 around the first (vertical) rotation axis to enable the supporting surface 2 to rotate on a horizontal plane around the first rotation axis A (orientation on a horizontal plane).

[0040] The connection joint 17 may comprise, as in these embodiments, an inner body 19 arranged in a cavity of the outer body 18. The inner body 19 is coupled with the outer body 18 and is movable in the aforesaid cavity. The cavity is bounded by an inner surface of the outer body 18 in the form of a ball portion. The inner body 19 comprises an outer surface in the form of a ball portion. The outer surface of the inner body 19 has grooves (tracks) in which balls 20 are slidingly arranged, each of which is housed in a seat obtained in the outer body 18.

[0041] The connection joint 17 comprises a pin 21 that traverses a hole obtained in the inner body 19. The pin 21 comprises a (lower) first end connected to the element (fork) that has the supporting surface 2 and a second (upper) end, opposite the first end, connected to at least one drive element that is suitable for controlling the tilt variation of the supporting surface 2.

[0042] The first rotation axis A comprises, in this embodiment, the rotatable coupling between the outer body 18 (in the form of a rotating sleeve) and the corresponding hole in the arm 15. The axis of the outer body 18 always remains vertical and parallel to the rotation axis of the arm 15 (second rotation axis B). The connection joint 17 is, substantially, in the cavity defined by the outer body 18. The pin 21 that traverses the inner body 19 of the joint 17 is configured for supporting the group that comprises the supporting surface 2. The absolute tilt of the pin 21 with respect to the vertical axis, i.e. to the first rotation axis A, is regulated by the drive element (governed by the control system of the stacker crane 1).

[0043] The drive element comprises a linear actuator 22, for example an electrically driven actuator, in particular an actuator with recirculating ball screw or with a nut screw made of bronze or plastics. The second (upper) end of the pin 21 is connected, by an articulation, to a movable element (stem) of the actuator 22. The drive element is adjusted in such a manner that the supporting surface 2, when it moves in a horizontal direction F, adopts the tilted forward position in the acceleration step (figure 8) and the tilted backwards position in the deceleration step (figure 10).

[0044] The supporting surface 2 may perform movements controlled by the drive element (actuator 22) around the connection joint 17 so as to raise and lower, selectively, the distal end of the supporting surface. As said, the distal end is the end of the supporting surface 2 that is further from the connection joint 17, or further from the aforesaid vertical plane.

[0045] The supporting surface 2 is provided with at least one rolling element 23 coupled with an end of the supporting surface 2 opposite the aforesaid distal end. In this embodiment two rolling elements 23 are arranged that are next to one another. The rolling elements 23 are arranged to rest on an outer element (for example a shelf of a shelving of a warehouse) to act as a support pin when the aforesaid distal end is raised and/or lowered.

[0046] In the embodiment of figure 11, the stacker crane comprises a mechanism configured for varying a relative angular position of the supporting surface 2 with respect to the arm 15 around the first rotation axis A through the effect of a variation of the relative angular position of the arm 15 with respect to the movable support 11 (carriage) around the second rotation axis B. The mechanism is configured, in particular, for maintaining constant the orientation of the supporting surface 2, i.e. the absolute angular position of the supporting surface 2 with respect to the advancement direction F (see figure 13). In this embodiment the mechanism comprises an articulated parallelogram 32. With 24, a rod is indicated that constitutes one side of the articulated parallelogram 32; the other sides of the articulated parallelogram 32 consist of the arm 15, of a first plate 34 and of a second plate 35 on which the rod 24 is articulated. The first plate 34 is fixed to the fork 33, whereas the second plate 35 is fixed to the movable support 11 (carriage).

[0047] In the embodiment of figures 1-10, the stacker crane comprises a fourth motor 25 (for example an electric motor or any other type of motor) arranged for varying an angular position of the supporting surface 2 around the first rotation axis A, in particular for varying the absolute angular position of the supporting surface 2 with respect to the advancement direction F (see figure 16). The fourth motor 25 is connected to the first rotation axis A by a motion transmission mechanism that may comprise, as in this embodiment, a flexible member 26 (belt) wound in a closed loop. The flexible member 26 is coupled with a first pulley 27 coaxial with the first rotation axis A and rigidly connected with the outer body 18 of the connection joint 17. The flexible member 26 may be coupled with a second pulley 36 coaxial with the second rotation axis B. The pulleys 27 and 36 may have the same diameter. In particular, the pulleys 27 and 36 are pulleys toothed with the same number of teeth. The second pulley 36 may be locked in rotation so as to permit behaviour that is identical to the aforesaid articulated parallelogram of the embodiment of figure 11, i.e. to maintain the orientation of the supporting surface 2 constant.

[0048] The stacker crane 1 comprises programmable electronic control means configured for controlling the drive element (actuator 22), and consequently also the tilt of the supporting surface 2, on the basis of at least one set value (for example a variation in the movement speed in the horizontal direction F that is detected, in particular, by the drive of the first motor 6) to drive the movement of the supporting surface 2 in a horizontal direction F.

[0049] In one embodiment that is not illustrated, the programmable electronic control means may be configured for controlling the drive element (actuator 22 of linear type) on the basis of at least one acceleration value detected by a sensor (for example an accelerometer) applied to the supporting surface 2 and/or to the movement system (for example to the arm 15).

[0050] The stacker crane 1 comprises at least one revolving contact element 28 and at least one contact or proximity sensor (for example an electrical contact). The revolving contact element 28 (for example a wheel located on one side of the supporting surface 2 and rotatably mounted with an axis perpendicular to the supporting surface) is arranged on a side edge of the supporting surface 2 to limit possible friction with an outer body (for example objects arranged in the warehouse). The contact sensor is arranged for sending a signal when the revolving contact element 28 touches an outer body. The signal may be used by the control means of the stacker crane 1 to control through feedback the movement of the supporting surface 2. Accordingly, the lateral contact elements 28, in addition to limiting possible friction, may be used to insert the tines of the forks correctly into the spaces between the bars of the shelf of the shelving of the warehouse, in particular with the possibility of retroactively correcting the interpolation between the translation of the first column 3 and the rotation of the arm 15.

[0051] In the embodiment of figure 17, The movement system comprises at least two columns, in particular a first column 3 (identical to the first column 3 disclosed previously) and a second column 29 parallel and stiffly connected to the first column 3 by at least one crosspiece 30. The second column 29 is movable in a horizontal direction on at least one (lower) second guide with sliding linearly parallel to and at the same height as the lower guide 4. The second column 29 is far from the first column 3 at a distance that is perpendicular to the aforesaid horizontal movement direction. The aforesaid distance is suitable for enabling the at least one shelving unit of a warehouse M to be arranged between the two columns 3 and 29.

[0052] The arm 15 supports a supporting surface 2 (fork), which is suitable for carrying the load and is able to tilt to compensate for the inertia forces on the load that are due to accelerations and decelerations in speed changes and/or is able to compensate also for possible aerodynamic resistances. The value of the tilt that compensates for the inertia forces (adjustable by the actuator 22) may be determined according to the acceleration value of the supporting surface 2. As said, this tilt value may be determined according to the setting parameters of the drives (the various motors 6, 13, 16, 25) of the movement system, in particular of the first horizontal movement motor 6 of the first column 3 of the stacker crane 1. The acceleration value of the supporting surface 2, which is usable for adjusting the value of the aforesaid tilt, may be detected directly with one or more inertia sensors.

[0053] The linear actuator 22 is mounted on the arm 15. In particular, the actuator 22 comprises an end (bottom side) coupled with the arm 15 (for example with turning coupling) and the opposite end (stem side) coupled with the pin 21 (for example with spherical coupling). The movable element of the actuator 22 is connected to the arm 15 by a rod 31 that on one side is pivoted on the arm 15 with a vertical axis pin and on the opposite side it has a collar that holds a portion of the movable element (stem) of the actuator 22. The rod 31 ensures that the supporting surface 2 is tilted around the joint 17 with the desired orientation (in particular along a vertical or almost vertical plane). The solution of using a simple rod 31 to guide the trajectory of the movable head of the linear actuator 22 is one of the many possible solutions. Alternatively, it is possible to use other guide means of the movable element of the drive element (actuator 22), for example linear guides that maintain the head of the actuator 22 on a (perfectly) vertical plane or articulations (that are more complex than the simple rod 31) that is able to compensate at least partially for the settling errors of the supporting surface 2 in the various angular positions that the arm 15 may adopt during complete rotation.

[0054] In figure 8 the supporting surface 2 is shown tilted forwards by about 20° with respect to the horizontal, for example to compensate for the inertia forces generated in an acceleration step at about 2 m/sec². In the figure, the supporting surface 2 is shown tilted backwards by about -20° with respect to the horizontal, for example to compensate for the inertia forces generated in a deceleration step at about 2 m/sec².

[0055] The aforesaid controlled variation of the tilt of the supporting surface 2, around the connection joint 17 could further compensate not only for the inertia forces (with a positive or negative tilt that depends, for example in a proportional manner, on the acceleration of the supporting surface 2), but also the aerodynamic resistance, calculating an additional tilt (also positive) that may be, in particular, proportional to the speed of the supporting surface and/or to the resistant section of the moved object (package C). The aerodynamic resistance may be detected directly by one or more sensors (for example one or more load cells) or may be determined according to the aerodynamic characteristics of the package C (for example on the basis of the aerodynamic resistance coefficient and/or the frontal area of the package). Such aerodynamic features may be presented in a database and may be combined with the package C (which is generally identifiable automatically by a barcode or other system).

[0056] In the system of figure 11 the controlled axes comprise, in addition to the horizontal linear movement, (controlled by the first motor 6) and to the vertical linear movement (controlled by the second motor 13), also the rotation of the arm 15 around the second rotation axis B (controlled by the third motor 16) and the tilt of the supporting surface 2 with respect to the horizontal around the joint 17 (controlled by the actuator 22). In this system, as can be seen, the orientation of the supporting surface 2 is kept constant with respect to the advancement direction F by the articulated parallelogram 32. Operationally, the arm 15 is suitable for operating on one side of the warehouse M, as illustrated in figure 13.

[0057] In the system of figures 1-10 the controlled axes comprise, in addition to those indicated, also the rotation of the supporting surface 2 around the first rotation axis A (controlled by the fourth motor 25) for varying the orientation of the supporting surface 2 on a horizontal plane independently of the rotation of the first arm 15 around the second rotation axis B. In this system, the arm 15 may operate on two opposite sides of the warehouse (as illustrated in figure 15) and may further load/unload frontally the packages in a central zone between the shelving.

[0058] Figure 16 shows some steps of the transition from the operating condition on one side of the warehouse to the operating condition on the opposite side, through the effect of the rotation of the supporting surface 2 around the first rotation axis A driven by the fourth motor 25. It is observed that in this case the supporting surface 2 may move in the horizontal direction F (horizontal movement of the column/s) whereas the plane rotates around the first rotation axis A to change the side of the warehouse on which to operate, nevertheless maintaining the peculiarity of compensating for the inertia forces on the moving load, as the supporting surface is always maintained tilted, with respect to the horizontal advancement direction F, precisely with a substantially appropriate tilt to compensate for the inertia forces. In fact, the arm 15 always remains substantially in the transferring position, i.e. roughly parallel to the horizontal movement direction F, so that, by rotating around the first rotation axis A (from one side to the other of the warehouse), the supporting surface 2 maintains roughly the same tilt with respect to the horizontal plane, i.e. always being tilted forwards (if accelerating) or backwards (if decelerating). In practice, it may be sufficient to adjust the absolute tilt of the central pin 21, determining the tilt in function of the acceleration of the load carried by the supporting surface (for example a tilt that is proportional to the acceleration of the load), without the need to provide a further adjusting drive to allow for the rotation of the supporting surface 2 on itself (around the first rotation axis).

[0059] It has been seen that the (articulated) joint 17 enables the inertia forces to be compensated for when the arm 15 is in the transferring position, i.e. when the arm 15 is (at least approximately) aligned on the horizontal translation direction F of the supporting surface (horizontal movement of the column/s). Regardless of this, the (articulated) joint 17 may be used to raise and lower the distal end of the supporting surface 2 (substantially, the tips or free ends of the tines of the fork 33), when the arm 15 is (approximately at least) orthogonal to the aforesaid horizontal movement direction F (translation axis of the column/s), as in the part further on the right of figure 13. This situation is also shown in figure 14, where the distal end (tips of the tines) may be lifted or tilted upwards (higher part of figure 14, where the plane is tilted by 5° with respect to the horizontal), not tilted (part in the centre of figure 14), lowered or tilted downwards (lower part of figure 14, where the plane is tilted by -3° with respect to the horizontal). This feature may be useful, in particular, when the supporting surface 2 (the tines of the fork) enter in depth into the shelving, with the risk of lowering the plane owing to the elasticity of the arm 15 under a load.

[0060] It is noted that the lower rolling elements 23 may contribute to the vertical support, especially when the supporting surface 2 enters the shelving to a great depth; in this case the actuator 22 may vary the tilt of the supporting surface 2 so as to raise the load with the lower rolling elements acting as a pivot; the latter may be positioned, in particular, on the side opposite the load with respect to the joint 17 around which the supporting surface 2 varies its tilt. With this lifting mode it is possible to reduce the stress and the deformation of the stacker crane, even when the cantilever protrusion of the arm is great. In other words, the possibility of acting as a pivot and varying the tilt of the supporting surface during lifting of the load enables operation at great lateral depth, even when using a movement system (in particular column guides) that is relatively light.

Claims

1. S tacker crane ( 1 ) , compri sing :

a movement system comprising at least one first controlled axis of movement in a horizontal direction (F);

- at least one supporting surface (2) for a load being moved by said movement system in said horizontal direction (F);

at least one connection joint (17) interposed between said supporting surface (2) and said movement system so that said supporting surface (2) is inclinable with the ability to assume, by displacements around said connection joint (17), at least one horizontal position, at least one forward inclined position and at least one backward inclined position, where "forward" and "backward" is understood with reference to a movement of said supporting surface (2) in said horizontal direction (F), whereby "forward" means that a front edge of said supporting surface (2) is lower with respect to said horizontal position and "backward" means that said front edge is higher with respect to said horizontal position;

at least one actuator (22) for controlling said displacements in such a way that said supporting surface (2), when it moves in said horizontal direction (F), assumes said forward inclined position in acceleration phase and said backward inclined position in deceleration phase.

2. Stacker crane according to claim 1, wherein said connection joint (17) is rotatably coupled to said movement system around a vertical first rotation axis (A) to allow said supporting surface (2) to rotate about said first rotation axis (A).

3. Stacker crane according to claim 2, wherein said movement system comprises at least one arm (15) that is rotatable around a vertical second rotation axis (B), said connection joint (17) being rotatably coupled to said arm (15) around said first rotation axis (A).

4. Stacker crane according to claim 3, wherein said first rotation axis (A) is at a distance from said second rotation axis (B), said arm (15) being extended along a longitudinal axis at least between said first rotation axis (A) and said second rotation axis (B), said arm (15) being capable of assuming at least one transfer position in which said longitudinal axis is parallel to said horizontal direction (F), or almost parallel, for example inclined with respect to said horizontal direction (F) within a range of + 5°, or + 10°, or + 15°, said actuator (22) being configured to incline forward or backward said supporting surface (2) when said arm (15) is in said transfer position.

5. Stacker crane according to claim 3 or 4, wherein said movement system comprises at least one column (3) extending in a vertical direction and movable in said horizontal direction (F), said movement system comprising at least one movable support (11) that is movable on said column (3) in said vertical direction along at least one second controlled axis of vertical movement, said arm (15) being rotatably coupled to said movable support (11) about said second rotation axis (B).

6. Stacker crane according to any one of claims 3 to 5, wherein said arm (15) is able of assuming at least one loading/unloading position in which it is perpendicular to a vertical plane passing through said horizontal direction (F), or almost perpendicular, for example inclined with respect to the perpendicular to said vertical plane within a range of + 5°, or + 10°, or + 15°, said supporting surface (2) being able to perform displacements controlled by said actuator (22) around said joint (17) so as to raise and lower, selectively, a distal end of said supporting surface (2), said distal end being the end of said supporting surface (2) that is most distant from said joint (17).

7. Stacker crane according to claim 6, comprising at least one rolling element (23) coupled to one end of said supporting surface (2) opposite to said distal end, said at least one rolling element (23) being arranged to go and rest on an external element to act as a fulcrum support when said distal end is raised and/or lowered.

8. Stacker crane according to any one of claims 3 to 7, comprising a mechanism (32) configured to vary a relative angular position of said supporting surface (2) with respect to said arm (15) about said first rotation axis (A) due to a variation in a relative angular position of said arm (15) with respect to said movement system around said second rotation axis (B); said mechanism (32) being configured, in particular, to maintain a constant absolute angular position of said supporting surface (2) with respect to said horizontal direction (F); said mechanism (32) comprising, in particular, an articulated parallelogram.

9. Stacker crane according to any one of claims 2 to 7, comprising motor means (25) arranged to vary an angular position of said supporting surface (2) about said first rotation axis (A), in particular to vary the absolute angular position of said supporting surface (2) with respect to said horizontal direction (F) of movement.

10. Stacker crane according to any one of the preceding claims, wherein said connection joint (17) comprises a hollow outer body (18) that is rotatably coupled to said movement system about said first rotation axis (A), an inner body (19) coupled to a cavity of said outer body (18) and movable in said cavity, and a pin (21) which passes through said inner body (19) and which includes a first end connected to said supporting surface (2) and a second end opposite to said first end and connected to said actuator (22); said actuator comprising, in particular, a linear actuator (22) with a movable element coupled to said second end.

11. Stacker crane according to any one of the preceding claims, wherein said connection joint (17) comprises a joint that is able to transmit torque and to allow inclinations in multiple directions, for example, a constant velocity joint of the type with balls or of the double Cardan type.

12. Stacker crane according to any one of the preceding claims, comprising: control means, in particular programmable electronic control means, configured for controlling said actuator (22), and consequently the inclination of said supporting surface (2), on the basis at least one set value to actuate said movement of said supporting surface (2) in said horizontal direction (F) and/or on the basis of at least one acceleration value or aerodynamic resistance value detected by a sensor applied to said supporting surface (2) and/or said arm (15).

13. Stacker crane according to any one of the preceding claims, comprising at least one rolling contact element (28) and at least one contact sensor, said at least one rolling contact element (28) being arranged on at least one side edge of said supporting surface (2) to limit a possible friction with an outer object, said contact sensor being arranged to send a signal when said at least one rolling contact element (28) touches an outer object, said signal being used by control means for feedback controlling at least one movement of said stacker crane (1).

14. Stacker crane according to any one of the preceding claims, wherein said movement system comprises: a first column (3) extending in a vertical direction and movable in said horizontal direction (F) on at least one linear sliding guide (4; 5); a movable support (11) that is movable on said first column (3) in said vertical direction along at least one second controlled axis of vertical movement; an arm (15) rotatably coupled to said movable support (11) around a second rotation axis (B) that is parallel to said first rotation axis (A); a second column (29) that is parallel and rigidly connected to said first column (3), said second column (29) being movable in said horizontal direction (F) and being distant from said first column (3) with a distance that is perpendicular to said horizontal direction (F), said distance being suitable so that a shelf of a warehouse (M) can be arranged in the space between the two columns.

15. An automatic warehouse comprising a stacker crane (1) according to any one of the preceding claims.