Patent Application
20220410408
The invention relates to a gripper unit, and in particular to a gripper unit being configured to attain, maintain, and terminate an interface between machinery and a packaging container.
Individual packaging containers, such as liquid food packaging containers, are typically produced from a carton-based material and filled using a high-speed filling machine. When the filled, formed, and sealed packaging containers are unloaded from the filling machine they are typically transferred to a cardboard packer in which a predetermined number of packaging containers are stacked in a packing pattern and placed in a case made from a cardboard blank, or to a film machine or similar equipment that encloses groups of packaging containers.
During such manufacturing, there is a need to move the packaging containers from one location to another. For example, packaging containers need to be moved from the filling machine (or any conveyor associated thereto) to the cardboard packer (or any conveyor associated thereto).
In order to move packages from one area to another within industrial machine equipment, a robot arm can be used. The robot arm may be programmed to move in three dimensions with various degrees of freedom. At the distal end of the robot arm, a gripper is arranged providing an interface between the machine and the packaging container.
Such packaging container interfaces are traditionally mechanical grippers, or vacuum cup grippers that operate on the upper plane of the packaging container. However, prior art grippers do not provide the speed nor stability required for the cycle time that is typically needed, i.e. the time needed to perform one complete operation. In modern manufacturing, grippers must be able to perform a complete handling sequence in 1 second or less.
Most constrains of prior art grippers bore down to the cycle time required. Problems stem from excessive robot movement being needed to accommodate the physical size and geometric requirements of a gripper. This includes positioning, activation, placing, release and careful withdrawal of the gripper in relation to the packaging container. Also, problems are related to excessive time required to evacuate the vacuum cups used to grip the packaging containers, as well as to excessive time needed to ensure that the vacuum has been completely broken so as not to disturb the packaging containers as the gripper retreats.
There is thus a need for an improved gripper unit, providing more robust, more accurate, and faster positioning of packaging containers.
It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. In particular, it is an object to provide a gripper unit which reduces any “pushing action” on the packaging container once the vacuum is removed for releasing the packaging container from the gripper unit.
According to a first aspect, gripper unit is provided. The gripper unit comprises a vacuum distribution unit connected to a housing such that linear motion of the vacuum distribution unit is allowed in a first direction towards and away from the housing. This improves accuracy of the gripper unit.
The gripper unit may further comprise at least a first leaf spring connecting the vacuum distribution unit to the housing.
The gripper unit preferably further comprises at least one additional leaf spring connecting the vacuum distribution unit to the housing.
The at least one additional leaf spring may have substantially the same length as the first leaf spring.
The at least one additional leaf spring may be arranged in parallel with the first leaf spring, but spaced apart in the first direction. Hence, rotation of the vacuum distribution unit is prevented in a plane defined by a central axis of the first leaf spring and a central axis of the additional leaf spring.
The gripper unit may comprise two additional leaf springs arranged on opposite sides of the first leaf spring. Symmetry is thereby achieved.
The gripper unit may comprise a plurality of gripper units according to the first aspect. In such embodiment it is possible to move a plurality of packaging containers using a single robotic arm.
The gripper unit may comprise at least one vacuum suction cup. The at least one suction cup is moveable between an idle position in which the at least one suction cup is arranged completely within a housing of the gripper unit, and an active position in which the at least one suction cup is extending out from said housing.
The gripper unit may comprise at least two suction cups operating in the same plane and being jointly movable between the idle position and the active position. Improved gripping of the packaging container is thereby achieved.
The position of the at least one suction cup may be controlled using vacuum, which allows for the use of readily available and high quality vacuum generators.
The gripper unit may further comprise a control suction cup. Activation of the control suction cup may urge the at least one suction cup to move from the idle position to the active position, which is advantageous in that a common air supply can be utilized for the attaching suction cups and for the control suction cup.
The control suction cup may be arranged inside a cavity of the housing, wherein said cavity is closed by a lid against which the control suction cup will apply a vacuum.
According to a second aspect, a robotic arm assembly is provided. The robotic arm assembly comprises a robot arm, such as an articulated robot arm or a delta robot, and at least one gripper unit being provided on the robot arm.
Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which
Starting in
The robotic arm assembly 1 is arranged in a machine environment, such as between a filling machine and a cardboard packer (not shown) or other type of equipment. In such example, the robotic arm assembly 1 is provided in order to move individual packaging containers 20, being produced by the filling machine and discharged therefrom by means of a conveyor 30. The packaging containers 20, which typically have a main body 22 including at least one planar panel 24, are gripped by the robotic arm assembly 1 as they are transported on the conveyor 30, and moved to a feeding conveyor 40 of the cardboard packer to be transported to further equipment downstream the conveyor 40. It should be noted that the planar panel 24 of the main body 22 must not necessarily form an entire side of the packaging container 20, but should preferably be a planar surface big enough to be gripped by the gripper unit 100.
The robotic arm assembly 1 is configured to operate at very high speed; from an idle position, it must be capable of performing the following motion sequence: arranging the gripper unit 100 in close proximity to the approaching packaging container 20, to activate the gripper unit 100 in order to attach the packaging container 20 to the gripper unit 100, to move the gripper unit 100 and the attached packaging container 20 to the desired position, to release the packaging container 20 by deactivating the gripper unit 100, and to return to the idle position. The complete motion sequence should typically be performed in less than 1 second, such as below 0.5 seconds, even more preferably below 0.3 seconds.
A controller 50 is therefore provided and connected to the gripper unit 100 in order to control activation and deactivation of the gripper unit 100. In some embodiments, the controller 50 is also in communication with the robotic arm 10.
The controller 50 preferably comprises a non-transitory computer-readable storage medium, storing one or more programs configured for execution by one or more processors, the one or more programs comprising instructions for controlling the gripper unit 100.
Now turning to
The gripper unit 100 comprises a housing 110 and a vacuum distribution unit 120. The vacuum distribution unit 120 is moveable in relation to the housing 110, and comprises at least one suction cup 130. In the shown example, the vacuum distribution unit 120 comprises two spaced apart suction cups 130 for attaching to the packaging container by applying vacuum, and one control suction cup 140.
All suction cups 130, 140 are preferably activated simultaneously. This is particularly the case when the suction cups 130, 140 share a common air supply (as will be described later). By activation of the suction cups 130 and the control suction cup 140, the vacuum distribution unit 120 is moved towards the housing 110, in the direction indicated by the block arrow in
In the active position, as shown in
The gripper unit 100 is used to collate individual packaging containers while they are in motion, necessitating the activation of the suction cups 130. The vacuum operated suction cups 130 need to interfere with the packaging containers that they are picking in order to attain a seal, and therefore a robust grip.
Should the suction cups 130 stand out of the housing 110 (and ready to contact a packaging container), it would possibly impede the collection of the packaging container. Thus, the gripper unit 100 described herein is configured to retract the suction cups 130, leaving a “clean” housing surface that does not impede packaging container movement.
In fact, the suction cups 130 are controlled to protrude to ensure the suction cups 130 meet the packaging container before the housing 110. The suction cups 130 are retracted by cutting off air supply to the vacuum generators 150, 152 (see
In the embodiment shown in
During operation, placement of the packaging container will be stable as the suction cups 130 withdraw from the packaging container, into the housing 110, as the vacuum is released. This is achieved by de-activating the control suction cup 140 and the suction cups 130 simultaneously, whereby the vacuum distribution unit 120 is allowed to return to its idle position of
Now turning to
As shown in
Still referring to
The vacuum generators 150, 152 may share a common air supply 154, thus making the connection of the gripper-unit 100 both simple and fast when change-overs or replacements of components are needed. As can be further seen in the drawings, the vacuum generators 150, 152 and the suction cups 130, 140 are placed in extreme proximity, thereby reducing the reaction times for pick and place of packaging containers 20.
An additional advantage of the gripper unit 100 is that the low-profile design allows the gripper unit 100 to work in close proximity to other packaging containers without causing crashes or collisions, and again reducing cycle time.
The gripper unit 100 reduces lost time by creating high-flow low-vacuum at the exact point of need, in a design that is dimensioned to reduce air consumption, and to reduce areas that are subjected to the vacuum. These features reduce the time needed to create a positive bond between the gripper unit 100 and an adjacent packaging container 20, and similarly reduce the time needed to release the bond.
In a preferred embodiment, the gripper unit 100 has no sliding or rotating parts; the lifetime will benefit from this. However, the vacuum distribution unit 120 should be allowed to move relative the housing 110 as explained above. Even more preferably, the vacuum distribution unit 120 should also be allowed to automatically return to its idle position once the control suction cup 140 is de-activated.
Accordingly, a gripper unit 100 is proposed where a housing 110 is connected to a vacuum distribution unit 120 in a way that allows for a linear motion of the vacuum distribution unit 120 towards and away from the housing 110, while at the same time preventing movement of the vacuum distribution unit 120 in any other direction.
An embodiment of such connection is shown in
The first leaf spring 170 is arranged at an inner part of the gripper unit 100, facing the robotic arm 10 during use, connecting the housing 110 to the rigid frame 122 of the vacuum distribution unit 120.
Two additional leaf springs 172 are preferably also provided, spaced apart from the first leaf spring 170. The two additional leaf springs 172 (of which only one is shown in
The motion of the vacuum distribution unit 120 is physically constrained by leaf springs 170, 172, which protect the vacuum distribution unit 120 against overtravel. The housing 110 is provided with two spaced apart T-shaped members 180 which form stop surfaces for the vacuum distribution unit 120 during activation and de-activation of the suction cups 130, 140. Due to the arrangement of the leaf springs 170, 172, the motion is guided in a pure longitudinal direction by use of the leaf springs 170, 172 disposed in a parallelogram configuration.
The beneficial effects of the first leaf spring 170 are thereby enhanced by the arrangement of the additional leaf springs 172 interconnecting the vacuum distribution unit 120 and the housing 110. The arrangement of the additional leaf springs 172 further reduces the freedom of movement of the vacuum distribution unit 120, such that it may essentially only move up and down in the first direction, as limited by a constant radii provided by each leaf spring 170, 172.
In particular, the addition of the additional leaf springs 172 reduces any torsion along the length direction of the primary leaf spring 170 or any bending of the leaf spring 170. Furthermore, arranging essentially equally long leaf springs 170, 172 in parallel but separated in the motion direction, provides a means of maintaining the orientation of the vacuum distribution unit 120, meaning that the vacuum distribution unit 120 is prevented from rotating.
In
Now returning to
Now turning to
From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19217884.6 | Dec 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/086685 | 12/17/2020 | WO |
