GRASPING SYSTEM AND METHOD FOR INSERTING SEPARATION SHEETS IN A RECEPTACLE

Abstract

The invention relates to grasping system comprising a grasping head (15) for a sheet transporting device, in particular for transporting an insert sheet to be inserted between rows of folding boxes in a receptacle, the grasping head (15) having at least one support frame (80) and a plurality of aspiration elements (17, 18). The aspiration elements (17, 18) are mounted on holding elements (50) which are received on the support frame (80) so as to be displaceable with respect to the support frame (80).

Claims

1. A grasping system for placing an insert sheet between rows of folding boxes in a receptacle, the grasping system comprising: a grasping head configured to grasp and pick up the insert sheet from a loading location, and displace and position the insert sheet on a depositing surface in the receptacle, the grasping head having a support frame and a plurality of gripping elements, the plurality of gripping elements configured to adhere to an upper surface of the insert sheet, the gripping elements being connected to the support frame via a plurality of holding elements, which are movably mounted to the support frame, and wherein the holding elements and the gripping elements are movable in a vertical direction in relation to the support frame when the gripping elements contact the insert sheet or the depositing surface in the receptacle, and wherein the grasping system further comprises a control unit and sensing arrangement, the sensing arrangement being configured to sense a vertical displacement of the holding elements with respect to the support frame, and wherein the control unit is configured to receive information from the sensing arrangement and determine when the grasping head is brought into contact with the insert sheet or the depositing surface.

2. The grasping system according to claim 1, wherein the control unit is further configured to stop a further vertical downward movement of the grasping head when the sensing arrangement senses a vertical movement of at least one of the holding elements.

3. The grasping system according to claim 1, wherein the depositing surface is an upper surface of a row of folding boxes or a bottom surface in the receptacle.

4. The grasping system according to claim 1, wherein the holding element is a rod which is received in an opening in the support frame, and wherein the rod comprises a free end onto which the gripping element is attached.

5. The grasping system according to claim 1, wherein the gripping elements are biased away from the support frame by biasing members.

6. The grasping system according to claim 1, wherein the control unit is configured to control the displacement of the grasping head and to operate the gripping elements in an alternating way between a gripping state and a release state such that the gripping elements are in a gripping state when the grasping head contacts the insert sheet in the loading location and in a release state when the grasping head subsequently contacts the depositing surface with the insert sheet.

7. The grasping system according to claim 2, further comprising a memory comprising spatial coordinates of a first descent position and spatial coordinates of a second descent position of the grasping head, the first and second descent positions defining a starting point of a first and second vertical descent trajectory, and wherein the first descent trajectory is vertically aligned with the loading location and the second descent trajectory is vertically aligned with the depositing location and wherein the control unit is configured to operate the grasping head to be moved into the first descent position and the second descent position, respectively.

8. The grasping system according to claim 7, wherein end points of the first and second vertical descent trajectories are defined by a first and second vertical end position, and wherein the first vertical end position and the second vertical end position are only defined by the sensing arrangement.

9. The grasping system according to claim 7, wherein the grasping system comprises a rectilinear guide and wherein the grasping head is linearly movable and guided by the rectilinear guide in a lateral direction, and wherein the descent positions are defined as one-dimensional coordinates in a horizontal plane in a direction along a longitudinal extension of the rectilinear guide.

10. The grasping system according to claim 1, wherein the sensing arrangement comprises at least one sensor located on the support frame and at least one detection element located on at least one holding element, and wherein the sensor is configured to sense a displacement of the detection element.

11. The grasping system according to claim 10, wherein the sensor is a magnetic sensor or an inductive sensor and the detection element comprises a metallic material.

12. The grasping system according to claim 1, wherein the support frame comprises a first frame portion comprising a first group of gripping elements and a second frame portion comprising a second group of gripping elements, and wherein the first and second frame portions are movable in relation to each other between a distal position in which the first and second group of gripping elements are located distal from each other and a proximate position, in which the gripping elements are located closer to each than in the distal position other, such that the first and second group of gripping elements are horizontally displaceable in relation to each other.

13. The grasping system according to claim 10, wherein the gripping elements are aspiration elements, configured to apply a suction force against the insert sheet.

14. The grasping system according to claim 13, wherein the control unit is configured to apply a vacuum to the grasping head when the sensor detects a displacement of the holding element with respect to the support frame and when the control unit determines that the grasping head is at the loading location.

15. The grasping system according to claim 14, wherein the gripping elements are configured to discharge air to apply a positive pressure against the insert sheet when the control unit determines the grasping head is in contact with the depositing surface.

16. The grasping system according to claim 1, wherein the control unit is configured to gradually stop/decelerate a downward movement of the grasping head when the sensing arrangement detects a vertical displacement of the holding element with respect to the support frame.

17. A method of introducing an insert sheet into a receptacle or between rows of folding boxes by using a grasping head comprising a plurality gripping elements which are mounted on vertically displaceable holding elements, movably connected to a support frame including a first frame portion and a second frame portion, the method comprising: moving the grasping head to be vertically aligned with a loading location and lowering the grasping head so that the gripping elements contact an upper surface of the insert sheet, moving the support frame further downwards a predetermined distance whereby the support frame moves in relation to the holding elements and the gripping elements remain stationary against the upper surface of the insert sheet, detecting a displacement of at least one holding member and stopping a further downward movement of the grasping head, grasping the insert sheet such that the insert sheet adheres to the gripping elements, moving the first frame portion closer towards the second frame portion such that the insert sheet is folded, picking up, displacing, and positioning the insert sheet such that the insert sheet is aligned with an opening in the receptacle, lowering the grasping head and placing the insert sheet on a depositing surface in the receptacle, moving the support frame further downwards a predetermined distance whereby the support frame moves in relation to the holding elements and while the insert sheet remains stationary against the upper surface of the insert sheet, detecting a displacement of at least one holding element and stopping a further downward movement of the grasping head, and releasing the gripping elements from the insert sheet.

18. The method according to claim 17, further comprising: detecting, with a sensor, a vertical displacement of the holding elements in relation to the support frame, and stopping the vertical movement of the grasping head.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The invention will now be described by way of example and with reference to embodiments shown in the enclosed drawings, where the same reference numerals will be used for similar elements and in which:

[0093] FIG. 1 shows elements of a filling station, in particular a box conveyor/filler, a receptacle conveyor, and an inserting device according to the prior art;

[0094] FIG. 2a shows an example of a receptacle with side walls shown as transparent, the receptacle being loaded with folding boxes arranged in orderly manner with a folded insert sheet inserted between the two rows of boxes;

[0095] FIG. 2b shows another example of a receptacle whose side walls are shown as transparent, the receptacle being loaded with folding boxes arranged in orderly manner with a folded insert sheet inserted between the two rows of boxes, and with two levels of folding boxes, a folded insert sheet being inserted between two levels;

[0096] FIGS. 3a and 3c show a cross sectional view of the receptacle, the folding boxes and the insert sheets of FIGS. 2a and 2b;

[0097] FIG. 3b shows a view similar to FIG. 3a in which the folding boxes have been removed;

[0098] FIG. 4a shows a diagram of an insert sheet before folding, seen from above;

[0099] FIG. 4b shows a perspective view of the insert sheet of FIG. 4a during the folding process;

[0100] FIG. 5 shows a perspective view of the inserting device of FIG. 1;

[0101] FIG. 6 shows a perspective view of a grasping head of the inserting device of FIG. 5 with hood elements shown as being transparent, the aspiration elements being represented in the grasping position;

[0102] FIG. 7a shows a view of the grasping head of FIG. 6 where the hood elements have been removed to better display an actuating mechanism;

[0103] FIG. 7b shows a view similar to FIG. 7a with the aspiration elements in the folding position;

[0104] FIG. 8a shows a side view of the grasping head of FIG. 7a;

[0105] FIG. 8b shows a side view of the grasping head of FIG. 7b;

[0106] FIG. 9 shows a perspective view of the grasping head of FIG. 7b having pivoted 180° and carrying a folded insert sheet;

[0107] FIG. 10 shows a grasping head according to an embodiment of the present invention in a perspective view;

[0108] FIG. 11 shows a side view of the grasping head of FIG. 10 in a condition in which it is lowered onto an insert sheet;

[0109] FIG. 12 shows a side view of the grasping head of FIG. 10 in a condition in which it is placed on an insert sheet;

[0110] FIG. 13 shows in a perspective view the insert head of FIG. 12 in a condition in which an insert sheet is being grasped;

[0111] FIG. 14 shows in a perspective view the insert head of FIG. 13 in a condition in which an insert sheet is being transported; and

[0112] FIG. 15 shows in a perspective view the grasping system according to the present invention.

DETAILED DESCRIPTION

[0113] An embodiment of the present invention will now be described with reference to FIGS. 10 to 15. For those elements which are known from FIGS. 1 to 9, the same reference numerals are used, and only the differences in construction and operation between the grasping head of the prior art and the grasping head as shown in FIGS. 10 to 14 will be discussed in the following.

[0114] A main difference between the prior art grasping system and the grasping system 15′ of FIGS. 10 to 14 is that gripping elements 17, 18 of the grasping head 15 according to the present invention are mounted to the grasping head 15 so as to be displaceable with respect to support bars 21, 22 of the support frame 80. In particular, the gripping elements 17, 18 are mounted so as to be displaceable in a direction which is parallel to the vertical direction along which grasping head 15 is moved by drive means 16 when descending to pick up or deposit an insert sheet 11.

[0115] In the embodiment shown in the drawings, the gripping elements 17, 18 are mounted at the lower ends of holding elements 50, which are here formed as rods. The lower ends of the holding elements 50 are configured as free ends, onto which the gripping elements 17, 18 are mounted. The holding elements 50 are displaceably received in the support bars 21, 22. In the illustrated example, and as best seen in FIG. 13, the holding elements 50 are received within openings 52 provided in the support bars 21, 22. The gripping elements 17, 18 are displaceable in a direction defined by the axial extension of the holding elements 50.

[0116] At the upper ends of holding elements 50, a stop 54 is arranged. The stop 54 limits the downward movement of the holding elements 50 with respect to support bars 21, 22 by abutting at the upper surfaces of the support bars 21, 22.

[0117] Underneath the support bars 21, 22 of the support frame 80 (and thus between the support bars and the gripping elements 17, 18, a biasing means 56 is provided which biases the gripping elements 17, 18 away from support bars 21, 22. In the illustrated embodiment, the biasing means 56 are formed as compression springs 56 mounted around the rod-shaped holding elements 50. As best seen in FIG. 14, the compression springs 56 are suspended between a first abutment surface 57 located on the support frame 80 and a second abutment surface 59 located on the holding elements 50.

[0118] As illustrated in the figures, the gripping elements 17, 18 are preferably configured as aspiration elements 17,18. The aspiration elements 17, 18 are connected to a vacuum generator (not shown). However, other types of mechanical gripping elements are also possible. For applying a vacuum to the aspiration elements 17, 18, a vacuum connection 60 is provided at the grasping head 15. The vacuum connection 60 is connected via vacuum lines 62 to a distribution line 64 which in turn is connected to the upper ends of holding elements 50 (the end which is opposite to the end at which aspiration elements 17, 18 are provided).

[0119] From the upper end of holding elements 50, a bore or duct extends in the interior of holding element 50 towards aspiration elements 16, 17 so that a vacuum can be applied to aspiration elements 17, 18 by applying a vacuum to vacuum connection 60. The vacuum duct can also be configured to discharge/blow air in order to release the vacuum and push the insert sheet 11 away from the aspiration elements 17, 18 as the insert sheet 11 is to be placed on top of the row of folding boxes 3.

[0120] As best seen in FIGS. 13 and 14, associated with at least one of holding elements 50 is a sensing arrangement 66, comprising a sensor 70 for detecting a displacement of a detection element 55 located on the respective holding element 50. The displacement is determined with respect to the support 20, 21 at which the holding elements 50 are mounted. Hence, the sensor 70 may be configured to sense when the detection element 55 is in proximity with the sensor 70 and is further configured to sense a displacement when the detection element 55 is moved further away from the sensor 70.

[0121] The sensor 70 can be a magnetic sensor or an inductive sensor. The sensor 70 is adapted for detecting a displacement of the respective holding element 50 upwardly with respect to the position shown in FIG. 11. The detection element 55 may be located on the stop 54 and preferably comprises a material which can be detected by the magnetic or inductive sensor 70. For instance, the material can be a metallic material.

[0122] As can be seen in FIG. 14, the detection element 55 on the stop 54 is arranged at the same vertical height as the sensor 70, and opposite the sensor 70 when aspiration elements 17, 18 are not pressed against the insert sheet 11 (in the loading location or against the row of folding boxes). Hence, the sensor 70 and detection element 55 are aligned when the gripping elements 17, 18 are located in their lowest position, in which they are placed at a maximum distance from the respective support frame 21, 22. As illustrated in FIG. 13, the detection element 55 on the stop 54 is arranged further away from the sensor 70 when the aspiration elements 17, 18 are pressed against the insert sheet 11.

[0123] In the embodiment illustrated in FIG. 10, the sensing arrangement 66 comprises one sensor 70 and one detection element 55. However, in the embodiment illustrated in FIG. 13, the grasping system 15′ comprises a first sensor 70a and a second sensor 70b which are reading a first detection element 55a and a second detection element 55b, respectively. This is advantageous when the support frame 80 comprises a first frame portion 80a comprising a first group of gripping elements 17 and a second frame portion 80b comprising a second group of gripping elements 18. The control unit 30 may be configured to receive signals from both sensors 70a, 70b and only enable the operation of the gripping elements 17, 18 when both sensor signals have been received. Hence, the operation of the gripping elements 17, 18 is enabled when both sensors 70a, 70b have determined a displacement of each respective detection element 55a, 55b.

[0124] Preferably, the first sensor 70a and the first detection element 55a are located on the first frame portion 80a, and the second sensor 70b and second detection element 55b are located on the second frame portion 80b. In an embodiment, the first sensor 70a and the second sensor 70b are arranged in a diagonal manner on the first and second frame portions 80a, 80b, respectively. In such a way, the first and second sensors 70a, 70b are arranged diagonally over the folding lines L1, L2. L3 when grasping the insert sheet 11. This enables a detection if the insert sheet 11 is not flat at its loading location 9 (e.g. if the stack of insert sheets 11 is not flat). In such a case, the grasping head 15 can be operated to activate the gripping elements 17, 18 when both the first detector 70a and the second detector 70b have sensed a contact with the insert sheet 11 (or deposit location). Optionally, a threshold distance can be applied to limit further downward movement after the first sensor 70a has sensed a contact. The threshold distance is the vertical distance of the grasping head 15 after the first sensor 70a has sensed a contact. For example, this threshold distance can be set to approximately 50 mm. The threshold distance enables deceleration and stop of the grasping head 15. Alternatively, instead of a threshold distance, a threshold time duration can be used. Similarly, the threshold time duration is set from the time when the first sensor 70a has sensed a contact. The threshold distance or threshold time enables a stop of the grasping head 15 if the second sensor 70b does not sense a contact.

[0125] Alternatively, a sensor 70 can be provided for each gripping element 17, 18. In the illustrated embodiment, there would be four sensors 70.

[0126] As best seen in FIG. 15, the grasping head 15 can be linearly operated in the lateral direction L and the vertical direction V. The lateral direction L is in the horizontal plane. The lateral direction L may be perpendicular to a transport direction T of the recipient 2 at the position of the grasping head 15.

[0127] A first descent position P11 for the grasping head 15 can be vertically aligned with the loading position P12 of the insert sheet 11 at the loading location 9. Similarly, a second descent position P21 for the grasping head 15 is located vertically aligned with a deposit position P22. The deposit position P22 is in the recipient 2. The first and second descent positions P11, P21 can be defined as coordinates in a memory 35 of the grasping system 15′. In an embodiment, the first and second descent positions P11, P21 are only defined in a first 11 and second lateral coordinate 12 in the lateral direction L. A restricted movement in the lateral direction L can be achieved by a rectilinear guide 31 configured to guide the grasping head 15 in the lateral direction L.

[0128] Hence, the first descent position P11 can be defined in a one-dimensional spatial coordinate I1. Similarly, the second descent position P21 can be defined in one-dimensional spatial coordinate I2. These coordinates I1, I2 define the starting points (in the horizontal plane) of vertical descent trajectories V1, V2 at the loading location 9 and the deposit location 13, respectively. The first descent trajectory V1 at the loading location 9 extends between the first descent position P11 and the first vertical end position P12 (corresponding to the loading position). The second descent trajectory V2 at the deposit location 13 extends between the second descent position P21 and the second vertical end position P22.

[0129] In another embodiment, there is no rectilinear guide. In this embodiment, the descent positions P11, P21 are defined in a two-dimensional horizontal plane defined by the longitudinal axis T and the lateral axis L. The coordinates I1, t1; I2, t2 define the descent positions P11, P21.

[0130] The control unit 30 is configured to retrieve the descent coordinates I1, I2 defining the descent positions P11, P21 from the memory 35. The control unit 30 positions the grasping head 15 in the descent positions P11, P21 and initiates the descent of the grasping head 15 in the vertical direction V along the descent trajectories V1, V2.

[0131] The first vertical end position P12 and the second vertical end position P22 may be defined by only the sensing arrangement 66. A stop signal is thus generated by the control unit 30 when the sensing arrangement 66 detects a displacement of at least one detection element 55. Hence, when a contact between the gripping elements 17, 18 and a surface has been sensed. The surface can be a stack with insert sheets 11 or a row of folding boxes. Alternatively, the stop signal is generated when a plurality of sensors 70a, 70b have sensed displacement of their respective detection element 55a, 55b. Still in another embodiment, the stop signal is generated when one sensor has sensed a displacement and the threshold distance or time has been exceeded.

[0132] The present sensing arrangement 66 thus enables the grasping head 15 to sense the position of the insert sheets 11 at the loading location 9 and also sense the depositing surfaces 13, 14 at the deposit location 13. The depositing surfaces 13, 14 correspond to a top surface 13 of a row of folding boxes 3, and the bottom surface 14 of the receptacle 2.

[0133] This is an important improvement, as in comparison with the prior art WO2017/202500A1, a simpler system can be achieved which automatically adapts to variable operating conditions. The previous system in WO2017/202500A1 needed more programming parameters, especially when several layers of insert sheets 11 had to be deposited at different heights in the receptacle 2 (as illustrated in FIG. 2b). Hence, the control unit needed to retrieve predefined data for each vertical deposit position. However, in reality, the vertical position at which the rows of folding boxes were actually positioned often differed slightly from the theoretical position. Therefore, in order to alleviate the risk of damaging the boxes, the grasping head was decelerated before the theoretical deposit position was reached even if a loss in speed was compromised. Contrarily, with the present system, only a short setup time and simple programming of the coordinates of the descent positions P12, P21 is needed in order to obtain a precise system.

[0134] In addition to the before-mentioned advantages, the present grasping system 15′ also improves reliability and durability. The grasping head 15 will automatically stop even if the sensed object is not an insert sheet 11 or a row of folding boxes 3. If for instance an object is present in the descent trajectories V1, V2 of the grasping head 15, the control unit 30 will also activate a stop of the grasping head 15 if a contact with the object has been sensed.

[0135] Another improvement in view of the system in WO2017/202500A1 is that the movable gripping elements 17, 18 are also configured to yield when a contact with an insert sheet 11 or a row of folding boxes has been detected. The stroke of the gripping elements 17, 18 can be selected such that the gripping elements 17, 18 are vertically movable after the sensing arrangement 66 has detected a contact. In such a way, the grasping head 15 can still yield against the stack of insert sheets or the row of folding boxes.

[0136] Optionally, in an embodiment, a time-lapse difference between the reception of the first sensor signal and the second sensor signal can be measured. If the difference exceeds a predefined threshold value, the control unit 30 may send an error signal to a central machine control system. Such a time difference between the sensor signals may be indicative of that the insert sheet 11 is picked up or deposited on an uneven surface.

[0137] In another (non-illustrated) embodiment, the sensing arrangement 66 comprises an electromechanical sensing switch comprising a mechanical latch configured to be activated at a predetermined displacement distance of the gripping elements 17, 18. The control unit 30 is configured to activate and deactivate the gripping elements 17, 18 in response to an activation of the electromechanical switch.

[0138] In FIGS. 10 and 11, the grasping head 15 is shown in a condition before being placed on an insert sheet 11. The aspiration elements 17, 18 have their maximum distance from the respective support 21, 22, and supports 21, 22 have a maximum horizontal distance from each other.

[0139] For grasping an insert sheet 11, the grasping head 12 is moved vertically downwards until the aspiration elements 17, 18 touch the upper surface of the insert sheet 11 arranged in a stack in a loading location 9. This process is best illustrated in FIG. 1, which general working principles also apply to the present grasping system 15′. This contact stops a further downward movement of the aspiration elements 17, 18. As the holding elements 50 are vertically movable in relation to the support frame 80, the supports 21, 22 are moved further downwardly, whereby the stops 54 move vertically upwardly. This changes of position of the detection element 55 on the stop 54 with respect to supports 21, 22 and can be detected by the sensor 70.

[0140] In response to the corresponding signal from the sensor 70, the control unit 30 stops the drive means 16 from displacing grasping head 15 further downwardly.

[0141] In an advantageous embodiment, the control unit 30 is configured to send instructions to the actuator 25, which gradually stops/decelerates the downward movement of the grasping head 15 when the sensing arrangement 66 detects a vertical displacement of the holding elements 50 with respect to the support frame 80). The gradual deceleration provides a more controlled and softer contact between the aspiration elements 17, 18 and the insert sheet. The decelerated distance enables the aspiration elements 17, 18 to establish the vacuum connection. The biasing devices 56 also enables the aspiration elements 17, 18 to yield when they contact the insert sheet 11, such that any undesired deformation of the insert sheet 11 can be avoided.

[0142] This condition of grasping head 15 is shown in FIG. 12. It can be seen that biasing devices 56 are in a compressed state as supports 21, 22 have been displaced downwardly on holding elements 50.

[0143] In this condition, a vacuum generator (not shown) is connected to aspiration elements 17, 18 and is activated so that the respective insert sheet 11 is grasped by the aspiration elements 17, 18. Thereafter, groups of aspiration elements 17, 18 can be moved towards each other in the horizontal direction H as illustrated in FIG. 12 so as to arrive in the condition shown in FIG. 13 in which insert sheet 11 is held with a fold 12. This is possible as the first frame portion 80a and the second frame portion 80b are horizontally movable in relation to each other between a distal position in which the first 17 and second group of aspiration elements 18 are located distal from each other and a proximate position, in which the first and second groups aspiration elements 17, 18 are located closer to each (than in the distal position other).

[0144] In a subsequent step, the grasping head 15 is lifted upwardly so as to also lift the insert sheet 11 as illustrated in FIG. 14. This results in that the biasing devices 56 return to their uncompressed state and moves the aspiration elements 17, 18 such that they return to a position in which they are placed at a maximum distance from the supports 21, 22.

[0145] The insert sheet 11 can then be transported to the position in the storage container where the insert sheet 11 should be deposited. The control unit 30 determines based on information from the sensing arrangement 66 when the grasping head 15 is brought into contact with a bottom portion of the storage container 2 or a top surface of a row of folding boxes 3 located in the storage container 2.

[0146] The control unit 30 then gradually stops/decelerates the downward movement of the grasping head 15 and releases the vacuum such that the insert sheet is deposited. The aspiration elements 17, 18 can then be configured to actively release the insert sheet 11 by discharging/blowing air.

[0147] Preferably, as previously described, the vacuum duct in the suction members 17, 18 is configured to discharge air in order to release the vacuum and push the insert sheet 11 away from the aspiration elements 17, 18 as the insert sheet 11 is to be placed on top of the row of folding boxes 3.