The present invention relates to a gripper for a depalletization machine and to a method of depalletization.
In general, depalletization machines are known with the purpose of disassembling unit loads, which comprise a pallet and a plurality of layers stacked on it.
In detail, the unit load comprises:
Furthermore, the unit loads comprise a plurality of pallet interlayers, which are sheets generally made of cardboard and may be placed:
Each layer of the unit load comprises a plurality of containers or boxes of containers, for example, bottles containing food products arranged next to one another.
The known depalletization machines comprise a thrust element, which is controllable to repeatedly thrust the containers forming one layer, so as to remove the layers from the unit load one after the other, starting from the uppermost layer of the unit load.
In detail, when the thrust element is operated, the current uppermost layer is horizontally moved, while the underlying layers and the pallet remain substantially stationary.
After the uppermost layer is removed from the unit load, the layer placed beneath the uppermost layer with respect to the vertical direction becomes the new uppermost layer of the unit load.
Eventually, after the penultimate layer with respect to the vertical direction is removed from the unit load, the lowermost layer becomes at the same time the new uppermost layer of the unit load.
However, when the thrust element of the known depalletization machines is operated, the pallet interlayer placed beneath the current uppermost layer must be held tight, in order to avoid possible interference with the functioning of the thrust element.
In detail, during the functioning of the thrust element the pallet interlayer placed beneath the current uppermost layer could undesirably move with respect to the pallet.
The known depalletization machines comprise two kinds of grippers for this purpose.
In detail, a first kind of grippers is configured to grip one pallet interlayer placed between two consecutive layers of the unit load, by gripping both of its sides along the vertical direction.
A second kind of grippers is configured to grip the pallet interlayer placed between the pallet and the lowermost layer, by gripping only one of its sides along the vertical direction.
Grippers of first and second kinds cannot be used interchangeably.
On the one hand, if a gripper of the first kind were used to grip the pallet interlayer placed between the pallet and the lowermost layer, there would be interference between the gripper and the pallet.
On the other hand, if a gripper of the second kind were used to grip one pallet interlayer placed between two consecutive layers of the unit load, there would not be an effective gripping, because the gripper of the second kind is not configured to grip both sides of the interlayer along the vertical direction.
In particular, the known depalletization machines comprise three grippers of the first kind and two grippers of the second kind.
The two grippers of the second kind are generally interposed between the three grippers of the first kind, forming an ordered array in a direction transversal to the vertical direction.
As a consequence, since grippers of both the first and the second kinds need to be used to grip the pallet interlayers, the known depalletization machines are affected by various drawbacks.
In fact, each kind of grippers requires different mounting and maintenance operations and replacement parts.
This is very disadvantageous, because it causes major economic losses.
A need is therefore felt within the industry for improved grippers, which allow to solve the drawbacks of the known depalletization machines.
It is an object of the present invention to provide a gripper for a depalletization machine, allowing to meet the aforementioned need in a simple and cost-effective manner.
This object is achieved by a gripper, as claimed in claim 1.
The invention also relates to a method of depalletization, as claimed in claim 11.
One preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
In the following of the present description and in the claims the expression “in use” means “during operation”.
With reference to
It is also possible to define two directions X, Y, which are transversal to each other and to direction Z.
Each layer 6, 6a, 6b of unit load 5 comprises a plurality of containers or boxes of containers 10, for example, bottles or cans.
In detail, bottles or cans may be empty or filled with food products.
As shown in
Unit load 5 comprises, with reference to direction Z:
In a unit load 5 comprising only one layer 6, 6a, 6b, uppermost layer 6a and lowermost layer 6b coincide.
Preferably, pallet 7 protrudes from layers 6, 6a, 6b along directions X and/or Y (
Furthermore, unit load 5 comprises (
Preferably, interlayers 11, 12, 13 protrude from layers 6, 6a, 6b along directions X and/or Y (
Interlayers 11, 12, 13 are generally made of cardboard or a polymer material.
In the embodiment shown, interlayers 11, 12, 13 are equal to each other.
Depalletization machine 1 comprises (
Depalletization machine 1 further comprises (
Support platform 9 and unit load 5 placed on support platform 9 are movable along direction Z by means of chain or belt drives.
Furthermore, container discharge station 3 and interlayer discharge station 4 are arranged on opposite sides of support platform 9 along direction X.
In the embodiment shown, container discharge station 3 comprises a conveyor (not shown), for conveying containers 10 removed from unit load 5.
Interlayer discharge station 4 comprises a discharge container (not shown), in which interlayers 11, 12, 13 removed from unit load 5 are collected.
In the embodiment shown, thrust element 2 reciprocates parallel to direction X, so as to horizontally move containers 10 of the current uppermost layer 6a of unit load 5 towards container discharge station 3 (
After uppermost layer 6a is removed from unit load 5, the layer 6 placed beneath uppermost layer 6a with respect to direction Z becomes the new uppermost layer 6a of unit load 5.
Eventually, after the penultimate layer 6 with respect to direction Z (i.e. the closest layer 6 to lowermost layer 6b) is removed from unit load 5, lowermost layer 6b becomes at the same time the new uppermost layer 6a of unit load 5.
Thrust element 2 translates on guides 14, which are directed parallel to direction X and fixed to fixed base 51 (
Thrust element 2 comprises, in turn (
Preferably, thrust element 2 removes only one layer 6, 6a, 6b at a time from unit load 5.
Interlayer removal element 8 reciprocates along direction X as well, so as to grab interlayers 11, 12, 13 and to move them towards interlayer discharge station 4.
In detail, interlayer removal element 8 translates on guides 15, which are directed parallel to direction X and fixed to fixed base 51 (
In the embodiment shown, guides 15 are placed above guides 14 with respect to direction Z.
Interlayer removal element 8 comprises:
Interlayer removal element 8 may be an automatic handling system of any kind; in the embodiment shown, grabbing means 21 comprise suction cups 16.
Depalletization machine 1 further comprises a conveyor 17, which is configured to convey unit load 5 towards support platform 9 (
Furthermore, depalletization machine 1 comprises a plurality of grippers 22, three in the embodiment shown (
Only one gripper 22 is disclosed, being grippers 22 identical to one another.
Each gripper 22 comprises, in turn:
As shown in
In detail, arms 24, 25 are symmetrical with respect to an axis A of gripper 22, which is preferably directed parallel to direction X.
In the embodiment shown, gripper 22 is at a fixed position along direction Z with respect to guides 14 and unit load 5 is translated parallel to direction Z by means of support platform 9 (
Furthermore, arms 24, 25 are movable between respective retracted and forward positions with respect to frame 23 along axis A.
In the embodiment shown, the retracted positions of arms 24, 25 correspond to respective minimum distances between homologous points of arms 24, 25 and frame 23; the forward positions of arms 24, 25 correspond to respective maximum distances between homologous points of arms 24, 25 and frame 23.
Advantageously, arms 24, 25 are movable independently of each other and gripper 22 is settable at least in:
Gripper 22 is further settable in a third configuration, in which arms 24, 25 are both in respective retracted positions (
Gripper 22 is set in the third configuration when interlayers 11, 12, 13 need not to be held tight, for example during the translation of support platform 9 parallel to direction Z, so as to avoid interference between gripper 22 and unit load 5.
Gripper 22 further comprises actuators 34, 35, which are related to arms 24, 25 respectively, and are selectively settable in respective contracted positions (
Actuators 34, 35 are linear and arranged parallel to axis A.
In the following of the present description and in the claims the length of actuators 34, 35 parallel to axis A must be intended as the length of actuators 34, 35 outside frame 23.
In detail, actuators 34, 35 are in the respective contracted positions, when they have respective minimum lengths parallel to axis A and in the respective extended positions, when they have respective maximum lengths parallel to axis A.
In further detail, arm 24 is in the retracted or forward positions when actuator 34 is in the contracted or extended positions respectively (
Arms 24, 25 are articulated on frame 23 and on respective actuators 34, 35.
In detail, arm 24 is rotatable and translatable with respect to frame 23 independently of arm 25 and vice versa.
Furthermore, each arm 24, 25 comprises a gripping stretch 26, at a front free portion 27 of arms 24, 25, which is configured to hold tight one interlayer 11, 12, 13 (
Each arm 24, 25 further comprises a rear portion 28, which is connected to respective actuator 34, 35 and is opposite to front free portion 27 along axis A.
In detail, the retracted (forward) position of arms 24, 25 corresponds to the respective minimum (maximum) distances between homologous gripping stretches 26 and frame 23.
In addition, when gripper 22 is set in the first configuration, gripping stretches 26 of both arms 24, 25 are in contact with interlayer 12 and prevent it from moving (
Furthermore, when gripper 22 is set in the second configuration, gripping stretch 26 of arm 24 only is in contact with base interlayer 11 and exerts a force F on pallet 7 (
In detail, force F is directed parallel to direction Z and prevents base interlayer 11 from moving with respect to pallet 7.
When grippers 22 are set in the first or in the second configuration, axis A is preferably aligned with the midplane of the gripped interlayer 11 or 12 perpendicular to direction Z (
In the embodiment shown, when arms 24, 25 are in respective forward positions, respective gripping stretches 26 are directed substantially parallel to axis A (
In detail, stretches 29, 30 and 31 are formed in one piece.
Gripper 22 further comprises two cranks 32, 33 having respective first ends 32a, 33a and second ends 32b, 33b, which are opposite to respective first ends 32a, 33a (
In the embodiment shown, cranks 32, 33 are rectilinear and respective first, second ends 32a, 32b, 33a, 33b are rounded (
In detail, first ends 32a, 33a of respective cranks 32, 33 are hinged to frame 23 about respective axes B, C, which are directed transversally to axis A.
Furthermore, second ends 32b, 33b of cranks 32, 33 are hinged respectively to arms 24, 25.
As shown in
As a consequence, arms 24, 25 are rotatable with respect to frame 23 about respective axes B, C.
In detail, arm 24 is rotatable about axis B independently of the rotation of arm 25 about axis C and vice versa.
In addition, cranks 32, 33 have a shorter length than arms 24, 25 along axis A.
Depalletization machine 1 further comprises detecting means 50, only schematically shown in
Detecting means 50 are further configured to send the information to control unit 45 (
In the embodiment shown, detecting means 50 comprise a position transducer, e.g. an encoder.
Actuators 34, 35 comprise:
Rods 38, 39 have two respective opposite ends 38a, 38b; 39a, 39b.
In detail, ends 38a, 39a (not shown) are positioned inside respective cylinders 36, 37 and ends 38b, 39b are positioned outside respective cylinders 36, 37 (
Furthermore, rods 38, 39 comprise respective driving knobs 40, 41 at respective ends 38b, 39b (
As shown in
In detail, rods 38, 39 and respective cylinders 36, 37 form two linear pneumatic actuators.
In the embodiment shown, cylinders 36, 37 are double-acting cylinders and comprise two respective openings, for the passage of air.
Furthermore, arm 24 is hinged to rod 38 at end 38b and arm 25 is hinged to rod 39 at end 39b.
In detail, arm 24 is hinged at its rear portion 28 on knob 40 about an axis D and arm 25 is hinged at its rear portion 28 on knob 41 about an axis E (
As a consequence, arms 24, 25 are rotatable with respect to respective rods 38, 39 and are translatable with respect to frame 23 integrally with respective rods 38, 39.
Axes D and E are directed parallel to axes B and C.
Arms 24, 25 are in respective forward positions when knobs 40, 41 are in respective furthest positions from respective cylinders 36, 37 and in respective retracted positions when knobs 40, 41 are in respective closest positions to respective cylinders 36, 37.
Furthermore, grippers 22 are aligned parallel to direction Y and are located at the same height along direction Z with respect to guide 14 (
In addition, grippers 22 are mounted on a beam 42 of fixed base 51 (
Furthermore, grippers 22 are positioned on the side of unit load 5 close to interlayer discharging station 4.
Preferably, the three grippers 22 are controlled by control unit 45, so as to be set simultaneously in the same configuration.
In the embodiment shown (
Whenever interlayers 11, 12, 13 need not to be held tight, grippers 22 may also be translated parallel to axis A and away from unit load 5, so as to avoid interference between grippers 22 and unit load 5.
The operation of grippers 22 and depalletization machine 1 is described with reference to a condition, in which grippers 22 are set in the third configuration, i.e. arms 24, 25 are both in respective retracted positions (
The operation is further described with reference to a condition in which unit load 5 comprises a top interlayer 13.
Control unit 45 commands interlayer removal element 8 to remove top interlayer 13 (
In detail, interlayer removal element 8 translates along direction X on guides 15 (
In general, grippers 22 are not used to grip top interlayer 13.
Before or after the removal of top interlayer 13, support platform 9 and unit load 5 placed on support platform 9 is commanded by control unit 45 to translate along direction Z (
As support platform 9 and unit load 5 translate along direction Z, detecting means 50 detect the information on whether the interlayer placed beneath uppermost layer 6a to be thrusted is a base interlayer 11 or an intermediate interlayer 12 and sends the information to control unit 45.
After the translation of support platform 9 and unit load 5 along direction Z, thrust element 2 is commanded by control unit 45 to thrust the current uppermost layer 6a of unit load 5 towards container discharge station 3.
In detail, with the aim of thrusting layer 6, 6a, 6b, thrust element 2 translates along direction X towards container discharge station 3 (from right to left in
Preferably, while thrust element 2 translates towards container discharge station 3, interlayer removal element 8 translates towards interlayer discharge station 4 (
As thrust element 2 removes layers 6, 6a, 6b from unit load 5, unit load 5 is progressively emptied.
Eventually, after the penultimate layer 6 with respect to direction Z is removed from unit load 5, lowermost layer 6b becomes at the same time the new uppermost layer 6a of unit load 5.
In general, before thrust element 2 starts to thrust layer 6, 6a, 6b, control unit 45 controls grippers 22 on the basis of the information, so as to move them in the first or in the second configuration (
In case detecting means 50 detect that the interlayer placed beneath uppermost layer 6a is an intermediate interlayer 12, control unit 45 sets grippers 22 in the first configuration.
In this condition, both arms 24, 25 are in respective forward positions and grip both sides of intermediate interlayer 12 along direction Z (
In further detail, when grippers 22 are set in the first configuration starting from the third configuration, both actuators 34, 35 move from respective contracted positions (
As a consequence, rods 38, 39 telescopically slide with respect to respective cylinders 36, 37 parallel to axis A and knobs 40, 41 move from the respective closest positions to the respective furthest positions from respective cylinders 36, 37.
Since arm 24 is hinged at its rear portion 28 on knob 40 about axis D and arm 25 is hinged at its rear portion 28 on knob 41 about axis E, arms 24, 25 translate with respect to frame 23 integrally with respective rods 38, 39, move away from frame 23 (
At the same time, cranks 32, 33 rotate about respective axes B, C in respective anticlockwise and clockwise directions, with reference to
As a consequence, gripping stretches 26 of respective arms 24, 25 are set at the respective maximum distances from frame 23.
While thrust element 2 thrusts layer 6, 6a, 6b, grippers 22 in the first configuration grip intermediate interlayer 12, thus avoiding intermediate interlayer 12 to be undesirably moved with respect to pallet 7 and avoiding interference between intermediate interlayer 12 and thrust element 2.
After thrust element 2 has thrusted layer 6, 6a, 6b, control unit 45 sets grippers 22 in the third configuration, controls interlayer removal element 8 to remove intermediate interlayer 12 from unit load 5 and controls support platform 9 to upwardly translate parallel to direction Z (
In case detecting means 50 detect that the interlayer placed beneath the current uppermost layer 6a is a base interlayer 11, control unit 45 sets grippers 22 in the second configuration.
In this condition, arm 24 is in the respective forward position and grips one side of base interlayer 11 and arm 25 is in the respective retracted position (
In detail, when grippers 22 are set in the second configuration starting from the third configuration, actuator 34 moves from the contracted position (
As a consequence, rod 38 telescopically slides with respect to cylinder 36 parallel to axis A and knob 40 moves from the closest position to the furthest position from cylinder 36.
Since arm 24 is hinged at rear portion 28 on knob 40 about axis D, it translates with respect to frame 23 integrally with rod 38, moves away from frame 23 (
At the same time, crank 32 rotates about axis B in anticlockwise direction, with reference to
As a consequence, gripping stretch 26 of arm 24 is set at the respective maximum distance from frame 23.
While thrust element 2 thrusts layer 6, 6a, 6b, grippers 22 in the second configuration grip base interlayer 11 and exert a force F on pallet 7, thus avoiding base interlayer 11 to be undesirably moved with respect to pallet 7 and avoiding interference between base interlayer 11 and thrust element 2.
After thrust element 2 has thrusted layer 6, 6a, 6b, control unit 45 sets grippers 22 in the third configuration and controls interlayer removal element 8 to remove base interlayer 11.
The advantages of gripper 22 and of the method according to the present invention will be clear from the above description.
In particular, since arms 24, 25 are movable independently of each other, only one kind of gripper 22 is necessary to grip both base and intermediate interlayers 11, 12.
In fact, since arms 24, 25 are settable in the respective retracted or forward positions independently of each other, grippers 22 can be set in the first configuration, in which they are adapted to grip intermediate interlayer 12, or in the second configuration, in which they are adapted to grip base interlayer 11.
As a consequence, the number of different components of depalletization machine 1 is reduced, compared to the known depalletization machines discussed in the introductory part of the present description, with a considerable reduction of warehouse and installation costs.
In detail, the mounting operations, the maintenance operations and the allocation of replacement parts of grippers 22 are considerably simplified.
The applicant has found that a depalletization machine 1 with three grippers 22 is particularly advantageous as compared with the known depalletization machines, comprising three grippers of the first kind and two grippers of the second kind.
In addition, since grippers 22 are interchangeable, they can be positioned indiscriminately along direction Y.
Finally, it is apparent that modifications and variants not departing from the scope of protection of the claims may be made to the gripper and to the method according to the present invention.
In particular, machine 1 may comprise only one or two grippers 22.
Grippers 22 could be translatable along direction Z, so as to be placed at a variable position with respect to guides 14.
In addition, only two grippers 22 could be set in the second configuration so as to grip one side of base interlayer 11.
Unit load 5 might not comprise top interlayer 13.
Furthermore, the retracted positions of arms 24, 25 may correspond to respective first distances between homologous points of arms 24, 25 and frame 23, instead of to respective minimum distances.
In detail, the first distances are greater than the respective minimum distances between homologous points of arms 24, 25 and frame 23.
Similarly, the forward positions of arms 24, 25 may correspond to respective second distances between homologous points of arms 24, 25 and frame 23, instead of to respective maximum distances.
The second distances are smaller than the respective maximum distances between homologous points of arms 24, 25 and frame 23.
In further detail, the second distances are greater than the respective first distances.
Furthermore, actuators 34, 35 may be in the respective contracted positions, when they have respective first lengths parallel to axis A, which are greater than the respective minimum lengths and in the respective extended positions, when they have respective second lengths parallel to axis A, which are smaller than the respective maximum lengths.
In detail, the second lengths are greater than the respective first lengths.
In addition, when arms 24, 25 are set in the respective retracted positions and homologous points of arms 24, 25 and frame 23 are set at the respective first distances, actuators 34, 35 are set in the respective contracted positions and have respective first lengths parallel to axis A.
When arms 24, 25 are set in the respective forward positions and homologous points of arms 24, 25 and frame 23 are set at the respective second distances, actuators 34, 35 are set in the respective extended positions and have respective second lengths parallel to axis A.
Number | Date | Country | Kind |
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19213304.9 | Dec 2019 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/084329 | 12/2/2020 | WO |