Technical Field

The present invention relates to a gripper for the grip of loads.

Background Art

Retail companies, above all within large-scale organized distribution, need to reduce surface areas used as internal warehouse.

For such purpose, these companies avail themselves of third-party warehouses and logistics, each of which serves a plurality of retailers.

To these third-party warehouses pertain the goods packed on single-product pallets, which have to undergo re-palletizing procedures, so as to create multiproduct pallets, the composition of which is based on the requests of the single retailer (e.g., a supermarket).

The goods, or loads, are arranged on the relative single-product pallets in superimposed layers, often with separation elements, such as cardboard interlayer pads or the like, in between.

Each layer comprises a plurality of loads, the number and arrangement of which are determined by the size of the pallet, according to specific standards.

For the preparation of multi-product pallets, one or more operators manually take a certain number of loads from the single-product pallets and load them, according to the customer's order, and they arrange them suitably in a stack of goods, naturally loaded on a pallet, and this stack will go to make up the multiproduct pallet commissioned by that customer.

The remaining loads on the single-product pallet are sent to one of the secondary warehouses, where they are stocked until they themselves have to be used to form further multiproduct pallets.

This system is too expensive both because the use of secondary warehouses implies the occupation and management of extremely large surface areas inside the above third-party warehouses, and because the use of dedicated labor involves high costs, besides the fact that it does in fact represent a bottleneck in a system the rest of which is automated.

The re-palletizing operation is further complicated by the fact that it covers a multitude of loads having the most varied shapes and sizes, among which are: bundled plastic or glass bottles, i.e. groups of bottles held together by a shrink film, which constitutes a so-called "bundle";

other bundled loads different from plastic and glass bottles, such as bundled cans, bundled jars, bundled bricks (i.e. beverage containers, usually in multilayer cardboard);

boxes, i.e. any type of goods packaged in a box container, from tea bags to bottles of beer and wine, which are therefore very variable in size and weight. To get an idea of the variety of sizes of the boxes, one should think that, at present, the single-product pallet may comprise boxes ranging in size from 80 x 120 x 200 mm and 400 x 400 x 600 mm.

It is easy to understand, therefore, that for reasons of efficiency, the third-party warehouses feel the need to re-palletize loads regardless of the type, the weight and size, without damaging the goods.

This need has remained unsatisfied so far.

Description of the Invention

The main aim of the present invention is to provide a gripper for the grip of loads which permits, in a practical, easy and functional manner, to grip and re- palletize loads very different from one another, so as to prepare multiproduct pallets starting with single-product pallets, avoiding the use of the above secondary warehouses.

Within this aim, an object of the invention is to provide a gripper for the grip of loads which allows doing without the manual action of operator personnel or totally doing without labor.

Another object of the invention is to provide a gripper for the grip of loads which allows to overcome the mentioned drawbacks of the prior art in the ambit of a simple, rational, easy and efficient to use as well as low cost solution.

The above mentioned objects are achieved by the present gripper for the grip of loads, according to claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become evident from the description of a preferred, but not exclusive embodiment, of a gripper for the grip of loads, illustrated by way of an indicative, but not limitative example in the accompanying drawings in which:

Figure 1 is an axonometric view of the gripper according to the invention;

Figure 2 is a side view of the gripper according to the invention;

Figures 3 to 6 show, in a succession of side views, a first mode of operation of the gripper according to the invention;

Figures 7 to 10 show, in a succession of side views, a second mode of operation of the gripper according to the invention;

Figure 11 is an axonometric view of the auxiliary gripping unit having the gripper according to the invention;

Figures 12 to 17 show, in a succession of side views, a third mode of operation of the gripper according to the invention;

Figure 18 is an axonometric view of the gripper according to the invention in the gripping phase of a separation element;

Figure 19 is an axonometric view of the gripper according to the invention in the gripping phase of a pallet.

Embodiments of the Invention

With particular reference to such figures, reference number 1 globally designates a gripper for the grip of loads.

The gripper 1 according to the invention is particularly intended for use in the above-mentioned third-party warehouses, in which single-product pallets 2 arrive which carry loads 5 to be re-palletized on a multiproduct pallet 3.

It should be noticed that in the present description, by the word "pallet" reference is made to the assembly made up of both the pallet 4 and the loads 5 supported on it, and not to the pallet 4 alone.

The loads 5 are distributed on the pallet 4 to form layers, separated by sheet- shaped separation elements 6, usually cardboard sheets.

The types of loads 5 graspable by the gripper 1 are the most diverse: bundled plastic bottles, bundled glass bottles, boxes, bundled cans, bundled jars, bundled bricks, additional bundled loads other than plastic and glass bottles, unbundled goods in trays, etc.

The gripper 1 therefore has a universal use.

The gripper 1 comprises at least a base frame 7 associable with a load handling machine 8.

Usefully the load handling machine 8 consists of an anthropomorphous robot. Anthropomorphous robots are known in the sector and comprise an articulated arm having hinge joints which give it at least three degrees of freedom.

The arm 8 terminates at an attachment member 9 provided to carry the gripper 1 (and if necessary other devices) which defines, so to speak, the "wrist" of the arm, if the gripper 1 is considered as the "hand" of the anthropomorphous robot 8.

In this case, the gripper 1 is an interchangeable grip means, i.e., a so-called "end effector".

On the attached tables, the robot 8 of the invention is approximately shown from its attachment member 9, but this should be deemed as a mere choice of the representative kind and is not limiting within the scope of the invention. By means of the robot 8, the gripper 1 can be able to rotate with respect to prefixed axes with respect to the arm.

On the base frame 7 of the gripper 1 are mounted at least a fixed jaw 10 and at least a movable jaw 11, substantially plate-shaped and substantially vertical in use.

In this regard it is noted that in the present discussion, the expression "in use" refers to the configuration of normal use of the gripper 1, i.e. the one with which the loads 5 are grasped.

In this configuration, the base frame 7 is placed above the loads 5 and the jaws 10, 11 protrude from the base frame 7 downwards, remaining substantially vertical.

As obvious, the gripper 1 can be both shifted in translation and rotated by the robot 8, which as mentioned is equipped with several hinge joints, and therefore the jaws 10, 11 can be tilted in space in different ways depending on how the gripper 1 is oriented by the robot 8.

It is therefore necessary to establish a reference position, which precisely is that of normal use of the gripper 1, in which the jaws 10, 11, as said, are arranged substantially vertically.

It follows that in the present discussion, expressions such as "upper/top /above", "below/lower /bottom", and the like, are used with reference to the position of normal use.

One should also considers the fact that when it is stated that the jaws 10, 11 are "substantially vertical" it means not only that they can be arranged exactly along vertical planes, but also that they can have a slight inclination with respect to the vertical direction, between 0° and 15°.

In particular, in the embodiment shown in the figures, the jaws 10, 11 are slightly inclined towards each other so as to converge downwards.

The angle of convergence a, i.e. the angle of inclination of each jaw 10, 11 with respect to the vertical direction, is substantially between 0.5° and 5°.

More in detail, the fixed jaw 10 has an angle of convergence of 1.25°, while the movable jaw 11 has an angle of convergence equal to 3°.

This layout facilitates the grip of loads 5; when tightened on a load 5, in fact, the jaws 10, 11 tend to bend with the result that, in the grip configuration, they end up being perfectly vertical and abutted on opposite grip sides of the load 5.

The jaws 10, 11 have a very limited thickness, e.g. between 4 mm and 13 mm in total, to release the load 5 on the multiproduct pallet 3 substantially adjacent to the other loads 5 already positioned.

More in detail, the first jaw 10 has a thickness substantially constant and equal to 11 mm; the second jaw 11, on the other hand, has a thickness which, in the upper part, is substantially equal to 9.5 mm and which tapers downwards up to 5 mm at the bottom.

Notwithstanding the reduced thickness, at least one of the fixed jaw 10 and the movable jaw 11, preferably both, is so strong to allow the forced insertion thereof between two loads 5 arranged adjacent, as it will be explained in detail below.

To combine together strength and lightness and at the same time contain the thicknesses, the jaws 10, 11, as well as different parts of the base frame 7, are made of carbon fiber or composite materials reinforced with carbon fiber.

The fixed jaw 10 is fixed to the base frame 7, in particular at one side extremity of the base frame 7.

The fixed jaw 10, in particular, lies on a plane, indicated below as front surface F which in use is substantially vertical and which defines a first semi-space P, which contains all the components of gripper 1, and a second semi-space S substantially free (see figure 2).

In practice, the gripper 1 does not comprise components that protrude beyond the front surface F within the second semi-space S, at least in a starting configuration as shown in figure 2.

The gripper 1, in fact, is conveniently provided with an image acquisition device 12, e.g., having a camera 13 or other similar means, which is mounted on the base frame 7 in a manner movable between the starting configuration of Figure 2, in which it is entirely arranged in the first semi-space P, and a work configuration, in which it protrudes beyond the front surface F and enters the second semi-space S (Figure 3).

When in the work configuration, in practice, the image acquisition device 12 allows to detect the exact position of the load 5 to grasp, by communicating this to a processing unit which will use this information in subsequent operation stages of the system.

The movable jaw 11 is associated with the base frame 7 in a movable manner with respect to the fixed jaw 10 along a sliding direction D which in use is substantially horizontal to grip the load 5 when this is tightened between the jaws 10, 11.

In particular, the movable jaw 11 is mounted on guides 14 associated below with the base of the base frame 7 and at least a first actuator device is provided, preferably of the electric type, interposed between the base frame 7 and the movable jaw 11 for moving the latter along the sliding direction D; the first actuator device is not illustrated in detail in the figures.

The fixed jaw 10 and the movable jaw 11 respectively comprise a first lower end edge 10a and a second lower end edge 11a.

At least one of the lower end edges 10a, 1 la lies in use on a horizontal reference plane O.

In the embodiment shown in the figures, both lower end edges 10a, 11a lie in use on the horizontal reference plane O, which is precisely uniquely defined by the position taken by the lower end edges 10a, 1 la in the position of normal use of the gripper 1.

Alternative embodiments are however possible wherein one of the two jaws 10, 11 has a vertical extension different to the other and the lower end edges 10a, 1 la are arranged at different levels; in this case the horizontal reference plane O is the horizontal plane on which lies the lower end edge 10a, 11a which in use is located at the highest level.

The gripper 1 is also equipped with at least a suction device 15 which has an aspirating plane 16 substantially horizontal in use.

The suction device 15 is associated with the base frame 7 so as to move vertically in the space between the jaws 10, 11 between:

a substantially raised resting position, wherein the aspirating plane 16 is arranged above the horizontal reference plane O, such as shown e.g. in Figure 2; and

a substantially lowered first operating position, wherein the aspirating plane 16 is arranged below the horizontal reference plane O.

For the vertical movement of the suction device 15, the gripper 1 has:

a vertical guide system 17, 18, comprising e.g. one or more vertical uprights 17 associated with the suction device 15 and one or more guide sleeves 18, associated with the base frame 7 and inside which slide the vertical uprights 17;

at least a second actuator device 19, preferably of the electric type, interposed between the base frame 7 and the suction device 15.

The suction device 15 is connected in a fluidic manner, e.g. through flexible hoses and ducts, to an aspiration system 20, the type of a compressor or the like. The aspiration system 20 is e.g. mounted on the gripper 1 on board the base frame 7, but alternative embodiments are not rules out wherein, instead, it is carried by the robot 8 or is installed on the ground.

When the aspirating plane 16 is placed in the first operating position in contact with an upper side of the load 5, the aspiration system 20 is able to generate an aspiration force so as to allow the horizontal dragging of the load 5 and its moving away from another adjacent load 5.

Similarly, when the aspirating plane 16 is placed in the first operating position in contact with a separation element 6 or the pallet 4, it is able to generate an aspiration force so as to allow the lifting and removal of the separation element 6 or the pallet 4.

The suction device 15 can be placed in a second operating position, wherein the aspirating plane 16 is arranged above the horizontal reference plane O and rests on a top side of the load 5, to retain the load 5 during the grip by the jaws 10, 11 and therefore helps to firmly grip the load itself.

The gripper 1 also comprises at least an ejector element 21 associated with the base frame 7 in a manner movable along a substantially vertical direction, the ejector element 21 comprising at least a contact surface 22 able to rest on a top side of the load 5 and to retain it downwards during the lifting and removal of the gripper 1.

In practice, during the release of the load 5 on the multiproduct pallet 3, the base frame 7 is lifted taking with it the jaws 10, 11, while to the contact surface 22 is imposed a relative motion with respect to the base frame 7 which allows to remain in contact with the load 5.

This way the load 5 is retained on the multiproduct pallet 3 even when it would be raised by friction with the jaws 10, 11.

Usefully, in the embodiment shown in the figures, the ejector element 21 coincides with the suction device 15 and the contact surface 22 coincides with the aspirating plane 16.

Alternative embodiments, however, are not ruled out wherein the ejector element 21 and the suction device 15 are separate and distinct from one another. The gripper 1 also comprises an auxiliary gripping unit 23 which allows to grip particular types of loads 5 consisting of unbundled goods carried by trays 30. The auxiliary gripping unit 23 comprises:

at least a support structure 24 associated in a removable manner with the suction device 15;

at least a lateral suction body 25 for the grip of trays 30; and

- at least a stabilization surface 26 which, in use, can be placed above the horizontal reference plane O resting on an upper side of the load 5, to stabilize the load 5 during the grip by the jaws 10, 11. In particular, the auxiliary gripping unit 23 is normally separated from the rest of the gripper 1 and remains in a waiting warehouse placed in the proximity of the load handling machine 8.

When loads 5 need to be handled with trays 30, the suction device 15 is brought in the proximity of the waiting warehouse, is associated with the support structure 24 and picks up the auxiliary gripping unit 23, which is thus brought together with the suction device 15 in the space between the jaws 10, 11.

Advantageously, the auxiliary gripping unit 23 comprises movement means 27 interposed between the support structure 24 and the lateral suction body 25, for the movement of the lateral suction body 25 between an active position, wherein the lateral suction body 25 defines a suction surface 28 substantially vertical in use, and an inactive position substantially moved away with respect to the active position.

In the particular embodiment shown in the figures, the lateral suction body 25 is hinged to the support structure 24 around an axis of rotation which, in use, is substantially horizontal and parallel to the faces of the jaws 10, 11 and the suction surface 28 is defined by a plurality of aspiring recesses distributed on the lateral suction body 25 parallel to the axis of rotation.

The stabilization surface 26 is associated with the lateral suction body 25 and movable with it; thanks to the movement means 27, the stabilization surface 26, which is substantially flat, can be placed in a horizontal configuration to be resting on the upper side of the load 5.

The auxiliary gripping unit 23 comprises at least an auxiliary aspirating plane 29 which, in use, is substantially horizontal and is associated with the support structure 24.

When the auxiliary gripping unit 23 is picked up by the suction device 15, the auxiliary aspirating plane 29 is placed below the aspirating plane 16 and, through suitable connection openings not illustrated in detail in the figures, enters into fluidic connection with the aspirating plane 16 itself.

In this way the auxiliary aspirating plane 29 is able to perform the same functions as the aspirating plane 16 using its own aspirating force when placed in the first operating position. Using the gripper 1 it is possible to implement a method to grasp loads comprising the steps of:

a) identifying at least a load 5 to grasp with the gripper 1, the load 5 having opposite gripping sides 31, 32. This step of the method can be carried out, e.g., by means of the image acquisition device 12, as shown by way of example in Figure 3;

b) checking whether the load 5 to grasp falls into a first group of predetermined loads, into a second group of predetermined loads or into a third group of predetermined loads. In the particular embodiment shown in the figures the groups of loads are defined as follows:

the first group of predetermined loads comprises one or more of the following types of loads: boxes, bundled cans, bundled jars, bundled bricks, additional bundled loads other than plastic and glass bottles; the second group of predetermined loads comprises one or more of the following types of loads: bundled plastic bottles, bundled glass bottles; the third group of predetermined loads comprises unbundled goods carried by trays 30;

c) gripping the load 5 to grasp with the gripper 1, according to the following rules:

cl) if the load 5 to grasp has both gripping sides 31, 32 free, that is, not adjacent to a side of other loads 5, then each jaw 10, 11 has to be placed against a respective gripping side 31, 32, to tighten the load 5 to grasp in the gripper 1. In practice, for those singled loads 5 that are located on the single-product pallet 2 without being in the immediate vicinity of other loads 5, the jaws 10, 11 can fall from one side and from the other side of load 5 to grasp without sliding against it, to then be approached horizontally to the gripping sides 31, 32 once a predetermined height has been reached;

c2) if the load 5 to grasp has a first gripping side 31 free and a second gripping side 32 adjacent to a different load 5 and the load 5 to grasp falls into the first group, then:

the aspirating plane 16 is placed in the first operating position in contact with an upper side of the load 5 to grasp;

the load 5 to grasp is dragged horizontally to move it away from the different load 5. In this phase the aspirating plane 16 sucks the load 5 to grasp, lifts it up at least at a first lower corner 31a of the first gripping side 31 and moves it horizontally, making it slide on the underlying layer of loads 5, or on the pallet 4, at most only at a second lower corner 32a of the second gripping side 32, so as to avoid the jamming of the load 5 to grip against any corners protruding from the underlying layer of loads 5, or from the pallet 4 (Figure 4);

once the load 5 to grasp is moved away, also the second gripping side 32 becomes free and each of the jaws 10, 11 is placed against a respective gripping side 31, 32, to tighten the load 5 to grasp in the gripper 1 (Figure 5) in a manner similar to what was said in step cl);

at this point the load 5 can be placed on the multiproduct pallet 3, making the gripper 1 descend vertically to the desired point and then pulling it out by using the contact surface 22 to retain the load 5 downwards (Figure 6). In this regard it is noticed that if the load 5 to grasp should be placed in the vicinity of a wall 33, namely of a set of loads 5 already arranged on the multiproduct pallet 3 and stacked one above the other, the particular device to provide a starting configuration wherein there are no components that protrude beyond the front surface F within the second semi-space S allows to make the gripper 1 descend vertically without colliding with the wall 33;

c3) if the load 5 to grasp has a first gripping side 31 free and a second gripping side 32 adjacent to a different load 5 and the load 5 to grasp falls into the second group, then:

- one of the jaws 10, 11 is forcibly inserted between the second gripping side 32 and the different load 5. This stage of the procedure is carried out by placing the gripper 1 above the load 5 to grasp (Figure 7) and lowering the gripper 1 vertically (Figure 8). The penetration of one of the jaws 10, 11 between the two loads 5 is favored by:

the pliability of the bottles, when these are made of plastic; the elasticity of the film of the bundle, which allows the bottles, particularly those made of glass, to move relative to one another within the same bundle;

the presence of an upper flaring 34, defined by the necks 35 of the bottles which belong to two adjacent bundles 5. In fact, given that each neck 35 tapers towards the respective bottle cap, and is wrapped in adherence by the film, then two adjacent bundles 5 define between them, near the top, a V-shaped upper flaring 34 facing upwards (but it may have different shapes based on the appearance of the neck 35 of the bundled bottles). Therefore, the presence of the upper flaring 34 helps to permit a smooth introduction of the jaws 10, 11 between two different bundles 5, without the respective bottles or their film being damaged. The forced thrust of jaws 10, 11 between the bundle 5 to grasp and an adjacent one, produces an, albeit small, opening between these bundles 5, and in practice singularizes the bundle 5 to grasp;

subsequently the other jaw 10, 11 is placed in abutment with the first gripping side 31, to tighten the load 5 to grasp in the gripper 1 (Figure 9);

at this point the load 5 can be placed on the multiproduct pallet 3, making the gripper 1 descend vertically to the desired point and therefore pulling it out by using the contact surface 22 to retain the load 5 downwards (Figure 10);

c4) if the load 5 to grasp has a first gripping side 31 free and a second gripping side 32 adjacent to a different load 5 and the load 5 to grasp falls into the third group, then:

the auxiliary gripping unit 23 is associated with the suction device 15 (Figure 12);

the auxiliary aspirating plane 29 is placed in the first operating position in contact with an upper side of the load 5 to grasp (Figure 13);

- the lateral suction body 25 is placed in the active position in contact with a lateral flank of the tray 30 (Figure 14);

the tray 30 is dragged horizontally to move the load 5 to grasp away from the different load 5. In this phase the auxiliary aspirating plane 29 sucks the top side of the goods present on the tray 30, while the lateral suction body 25 operates directly on tray 30. The gripper 1 is moved so as to lift the load 5 to grasp at least at the first lower corner 31a of the first gripping side 31 and moves it horizontally, making it slide on the underlying layer of loads 5, or on the pallet 4, at the second lower corner 32a of the second gripping side 32, so as to avoid the jamming of the load 5 to grasp against any corners protruding from the underlying layer of loads 5, or from the pallet 4 (Figure 15);

once the load 5 to grasp has been moved away, the second gripping side 32 also becomes free. Then the stabilization surface 26 is placed in a horizontal configuration and resting on a top side of the load 5, to stabilize the load 5 to grasp during gripping by the jaws, and each of the jaws 10, 11 is placed against a respective gripping side 31, 32, to tighten the load 5 to grasp in the gripper 1 (Figure 16) in a manner similar to what was said in point cl);

- at this point the load 5 can be placed on the multiproduct pallet 3, making the gripper 1 descend vertically to the desired point and therefore pulling it out possibly using the stabilization surface 26 as a contact surface to retain the load 5 downwards (Figure 17).

Thanks to the suction device 15, moreover, the method according to the invention may also include a lifting and removal phase of the separation elements 6 (Figure 18) and/or of the pallet 4 (Figure 19), wherein the aspirating plane 16 is placed in the first operating position and exploits the aspiration force generated by the aspiration system 20 to grasp the separation elements 6 and the pallet 4.