Device for lifting and moving stack of flat products arranged one on top of other

Abstract

The invention relates to a device for lifting and moving a stack of flat products, such as folds, lying one on top of the other, comprising a robot-guided gripping device (30), which comprises a lower gripping element (31), an upper gripping element (33), which is designed as a clamping element, and a sensor (40), which is designed as a clamping element, the gripping elements (31, 33) can be moved towards the lower gripping element (31), and the sensor (40) is designed as a distance sensor (40a) or a proximity switch (40b) in such a way that the actual height (12) of the stack (10) gripped by the gripping device (30) and gripped between the gripping elements (31, 33) is determined using the sensor (40). The invention is preferably used in the graphics industry and in particular in the environment of folding machines or product taps thereof. According to the invention, a stack of flat products stacked on top of one another can be reliably gripped, transported and unloaded in a robot-guided manner in an advantageous manner.

Description

Technical Field

[0001] The invention relates to a device for lifting and moving stacks of flat products placed one on top of the other, having the features of the preamble to claim 1.

[0002] The invention belongs to the technical field of the graphics industry, in particular in the field of handling (e.g. gripping, holding, moving, rotating, flipping and / or unloading) stacks of flexible (and preferably printed and folded) flat products (e.g. leaflets) stacked on top of each other, preferably made of paper, cardboard, paperboard, plastic or a composite material, with the aid of a manipulator (in particular an articulated arm robot / folding arm robot with a robot arm and a gripping device for stacking). Background Art

[0003] In the post-press field, it is known that a stack of flat products is conveyed on a (e.g. roller) conveyor section, the stack is picked up by a gripper head arranged on a robot arm, the stack is lifted from the conveyor section, moved to a bracket or pallet located near the conveyor section, and unloaded there into a pallet stack, for example, as known from documents DE102020103398A1 or DE202019106975U1.

[0004] Document DE 202019 106 975 U1 discloses a conveyor section for stacks of printed products stacked on top of one another and a so-called collaborative robot system having a robot arm with a gripper for receiving the stack from the conveyor section and placing the stack on a pallet.

[0005] Document DE102020103398A1 also discloses a conveyor section for stacks of printed products stacked on top of each other and a robot having a robot arm with a gripper for receiving the stack from the conveyor section and placing the stack on a pallet. The robot can be configured as an industrial articulated arm robot.

[0006] Document FR3110152B1 also discloses a conveyor section and a robot-guided gripping head, which comprises a vertically movable upper gripping element, which is implemented as a clamping element, and a horizontally movable lower gripping element, which is implemented as a pair of fork teeth.

[0007] Document DE69420616T2 discloses a discharge system for discharging a stack on a pallet, which has a gantry robot and a gripper. The gripper comprises a suction-type upper gripper element and a swingable lower gripper element. In addition, a sensor is mounted on the gripper. The sensor detects the horizontal position of the stack in the gripper.

[0008] When discharging stacks of flat products stacked on top of each other, for example from a folding machine, it can happen that not all stacks have the same height or that some stacks contain fewer flat products. This could be the last stack of a production order, for example. Such stacks could be too low in height to be transported and discharged reliably by a robot-guided gripper head. Summary of the invention

[0009] The object of the present invention is therefore to provide a technical concept which is improved compared to the prior art and which in particular allows stacks of flat products stacked on top of one another to be reliably gripped, transported in a robot-guided manner and to be deposited.

[0010] The object solution according to the invention is:

[0011] The above object is achieved according to the invention by a device according to claim 1 .

[0012] Advantageous and therefore preferred developments of the invention are apparent from the dependent claims as well as from the description and the drawings.

[0013] According to the present invention, a device for lifting and moving a stack of flat products stacked on top of each other is proposed, the device having a robot-guided gripping device, wherein the gripping device comprises a lower gripping element, an upper gripping element and a sensor, characterized in that the upper gripping element is configured as a clamping element that can move toward the lower gripping element, and the sensor is configured as a distance sensor or a proximity switch, so that the actual height of the stack gripped by the gripping device and clamped between the gripping elements can be determined with the aid of the sensor.

[0014] Advantageous configuration and effects of the present invention:

[0015] The invention advantageously enables stacks of flat products stacked on top of one another to be reliably gripped, transported in a robot-guided manner and to be set aside.

[0016] The invention is preferably used in the graphics industry and has particular application in the context of a folder (or a product outfeeder of a folder).

[0017] The invention advantageously allows the height of a stack of flat products stacked on top of one another to be directly measured by means of a robot arm and a gripping head and thus allows a direct decision to be made as to whether the stack in question can be handled reliably. In this way, problems can be avoided during transport and in particular during unloading of the stack.

[0018] The invention also has the advantage that the height of a stack of flat products stacked on top of one another can be detected in the clamped state and thus the stack can be prevented from falling apart when the stack height is detected. This distorts the measurement.

[0019] The robot arm is preferably part of a robot system, which usually also includes a robot base, and which can be designed as a conventional industrial robot, which includes a fence for operator protection, in particular an articulated arm robot with three to seven rotation axes, or as a so-called collaborative robot system, in particular a so-called Cobot. The latter does not require a fence, because the system has its own force sensor and detects contact with the operator with the help of the force sensor and prevents possible injuries, for example by automatically stopping the robot arm movement. As an alternative to a Cobot, a collaborative robot system can also be realized by an industrial robot with an additional area scanner (detection of operators in the danger zone) and an automatic stop device.

[0020] Improvement scheme of the present invention:

[0021] Preferred improvements of the present invention (improvements for short) will be described below. These improvements can also be combined with each other as long as there are no technical exclusions.

[0022] One refinement can be characterized in that the sensor is designed as a distance sensor, which is arranged at the gripping device above the gripped stack and determines the distance. One refinement can be characterized in that the distance sensor measures the distance to the (upwardly directed) surface of the stack. One refinement can be characterized in that the distance sensor measures the distance to the (upwardly directed) surface of the clamping element or the clamping face of the clamping element. The distance sensor can preferably be designed as a laser triangulation sensor or an ultrasonic sensor.

[0023] A further development can be characterized in that the upper gripping element comprises a linear drive which serves as a distance sensor or its controller and which determines the distance. The linear drive preferably comprises at least one pneumatically actuated telescopic rod, for example two such rods are used in parallel.

[0024] One refinement can be characterized in that the distance sensor sends the distance to a computer and the computer calculates the actual height of the stack from the distance. One refinement can be characterized in that the actual height is compared with a setpoint height of the stack with respect to deviations. One refinement can be characterized in that it is detected whether the actual height is less than a predefined minimum height of the stack; this can also preferably be detected as a deviation.

[0025] One refinement can be characterized in that the computer calculates the actual weight of the stack as a function of the actual height. One refinement can be characterized in that the computer transmits the actual weight to the control of the robot and the control takes the actual weight into account when implementing the robot movements. In robot-guided product transport, in particular when using so-called cobots, knowledge of the actual weight is very important.

[0026] A further development can be characterized in that the sensor is designed as a proximity sensor / proximity switch The proximity switch is arranged at the gripping device next to the gripped stack. A refinement can be characterized in that the proximity switch detects, based on its (vertical) positioning, whether the actual height is less than a predetermined minimum height of the stack. A refinement can be characterized in that the proximity switch sends a signal to a computer and the computer determines the existing deviation from this. The proximity switch can be, for example, an inductive, capacitive or optical switch; alternatively, it can be a light barrier or a limit switch.

[0027] One development can be characterized in that, as a function of an existing (detected) deviation, a predefined interference warning is output (for example visually or acoustically) or a predefined interference mode (for example stop) is activated.

[0028] A further development can be characterized in that the sensor transmits its measurement results wirelessly to the computer. This is particularly advantageous in robot-guided transport, since in this way it is possible to avoid having to guide the line through or along a robot arm.

[0029] The features and feature combinations disclosed in the above technical fields, inventions and improvements and in the following example section represent further preferred developments of the invention in any combination with one another.

[0030] Alternative solutions:

[0031] As an alternative to the above-described embodiment, it can be provided that the height of the stack of flat products stacked on top of each other is detected before it is received by the gripper head, in particular on the conveyor section between an upstream machine (e.g. a folding machine) and the receiving position for the gripper head. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 and Figure 2 Preferred embodiments of the invention and its developments are shown. In the drawings, corresponding features are provided with the same reference numerals.

[0033] Figure 1 A schematic top view of a preferred embodiment of the device according to the invention is shown.

[0034] Figure 2 A schematic cross-section through a preferred embodiment of the device according to the invention is shown. DETAILED DESCRIPTION

[0035] Figure 1 A machine 2 for the graphics industry, preferably a post-processing machine 2 and in particular a folding machine 2, is shown in detail, as well as a (preferably linear) conveyor section 3 (for example a roller table 3 with transfer rollers) located downstream of the machine 2, which conveyor section 3 has a conveying direction 4 and a motor 5 for (preferably horizontally) conveying a continuous stack 10 consisting of flat products stacked one above the other, for example printed and folded paper.

[0036] also, Figure 1 A device 1 according to the invention for transferring stacks 10, in particular for unloading stacks 10 onto a pallet 52, is shown. The device 1 comprises a robot 20 having a movable robot arm 21 (e.g. an articulated arm 21), on which a gripping device 30 for gripping individual stacks 10 is arranged. The danger zone 23 is defined by the maximum movement of the robot arm 21. The gripping device 30 grips one stack 10 in each case, lifts it from the conveyor section 3 and holds the stack 10 during the robot movement 24 to the pallet 52. In this way, the stacks 10 conveyed from the machine 2 are unloaded one after the other onto the pallet 52 and form a pallet stack 53 on the pallet 52 (arranged side by side and one above the other according to a predetermined unloading scheme). The upper (and preferably complete) flat stack 10 forms the upper edge of the pallet stack 53. Figure 1 In the embodiment of the present invention, two pallets 52 are placed, by way of example, at one longitudinal side of the conveyor section 3. The robot 20 is also placed, by way of example, at this longitudinal side of the conveyor section 3; the robot 20 can alternatively also be arranged at the end of the conveyor section 3. The two pallets 52 can be loaded successively with stacks 10 by means of the robot 20; alternatively, the two pallets 52 can also be loaded alternately. A control device 25 is provided, which controls the movements 24 of the robot 20 when transferring the stacks 10.

[0037] Figure 2A device 1 according to the invention for lifting and moving a stack 10 of flat products stacked on top of one another is shown. The stack 10 has an upwardly directed surface 11 and a height (actual height) 12. The gripping device 30 (or gripping head 30) of the device 1 comprises a housing 30a, a first lower gripping element 31 movable horizontally 70, and a second upper gripping element 33 movable vertically 80; these gripping elements 31 and 33 are used to grip and hold / clamp each stack 10. The movement 32 of the lower gripping element 31 is carried out by means of a controllable linear drive 31a, for example a pneumatic cylinder. The movement 34 of the upper gripping element 33 is carried out by means of a further controllable linear drive 33a, for example a pneumatic cylinder and preferably a pneumatic telescopic rod; particularly preferably, two linear drives 33a operating in parallel are provided. The lower gripping element 31 is also shown in part in another position 31b, for example a position completely retracted into the housing 30a (indicated by dashed lines); in this position, no stack 10 is held. The gripping device 30 also includes two controllable suction grippers 36 for sucking, holding and transporting so-called intermediate layers 37 for the pallet stack. The housing 30a is arranged at the end of the robot arm 21 of the robot 20, preferably rotatable and / or swivellable via a joint 22.

[0038] The device 1 comprises at least one sensor 40. The sensor 40 can be designed as a distance sensor 40a and is preferably arranged on the housing 30a above the stack 10. The distance sensor 40a measures the distance 13 to the surface 11 of the stack 10. If the distance sensor 40a is arranged in another position 40c (indicated by dashed lines), it can also measure the distance 14 to the surface 35 of the second gripping element 33 (or gripping plate), the distance of which from the surface 11 is known during clamping. Alternatively, it can also be provided that the distance or height 12 is determined directly by the linear drive 33a (or the controller 33b of the linear drive 33a), i.e., for example, by the position of the upper gripping element 33 in the extended and clamped state.

[0039] Alternatively, the sensor 40 can be designed as a proximity switch 40 b and is preferably arranged on the housing 30 a next to the stack 10 ; preferably in a vertical position at a height of a predefined minimum height 15 of the stack 10 .

[0040] The results of the respective measurements (or measured values) can be transmitted to a (preferably digital) computer 41 (preferably wirelessly, i.e. via a radio connection which is only indicated symbolically), which performs calculations and thereby determines by calculation the actual height 12 of the clamped stack 10. The value of the actual height 12 (or the actual weight of the stack 10 derived therefrom) can be transmitted to the control device 25 of the robot 20. The warning device 42 can also be activated, for example, if problems can be expected during gripping, holding, clamping, transporting and / or unloading based on the measured actual height.

[0041] Reference numerals list

[0042] 1 device

[0043] 2Machines, especially folding machines

[0044] 3Conveyor sections, especially roller tables

[0045] 4 conveying direction

[0046] 5 Motor

[0047] 10 Stacks of flat products stacked on top of each other

[0048] 11 Stacking surface

[0049] 12 (Actual) height of stack

[0050] 13Distance from the surface

[0051] 14 Distance from the grabber

[0052] 15 Predetermined minimum height

[0053] 20Robots / Robot Systems

[0054] 21Robotic Arm

[0055] 22 joints

[0056] 23 Danger Zone

[0057] 24 (unloading) movement

[0058] 25Robot control device

[0059] 30 Grabbing device, grabbing head

[0060] 30a housing

[0061] 31 (lower part) first gripping element, horizontally movable

[0062] 31a Linear Actuator

[0063] 31b First gripping element in another position

[0064] 32 Movement directions

[0065] 33 (upper) second gripping element, vertically movable

[0066] 33a Linear Actuator

[0067] 33b controller

[0068] 34 Movement direction

[0069] 35 Surface of the second gripping element

[0070] 36 Suction grabber

[0071] 37 Middle Layer

[0072] 40 sensors

[0073] 40a distance sensor

[0074] 40b proximity switch

[0075] 40c Sensor in another position

[0076] 41 Computer

[0077] 42 Warning device

[0078] 50 Receiving position, at the conveyor section

[0079] 51 Unloading position, on the pallet

[0080] 52 Pallets

[0081] 53 Pallet stacking

[0082] 60The floor of the production workshop

[0083] 61 operators

[0084] 70 levels

[0085] 80 vertical

Claims

1. A device for lifting and moving stacks of flat products stacked on top of each other, the device having a robot-guided gripping device (30), wherein: The gripping device (30) comprises a lower gripping element (31), an upper gripping element (33) and a sensor (40). It is characterized in that The upper gripping element (33) is designed as a clamping element which can be moved toward the lower gripping element (31), and The sensor (40) is designed as a distance sensor (40a) or a proximity switch (40b), so that the sensor (40) is used to determine the actual height (12) of a stack (10) gripped by the gripping device (30) and clamped between the gripping elements (31, 33).

2. The device according to claim 1, It is characterized in that The sensor (40) is designed as a distance sensor (40a), is arranged on the gripping device (30) above the gripped stack (10), and determines the distance (13, 14).

3. The device according to claim 1, It is characterized in that The upper gripping element (33) comprises a linear drive (33a), The linear drive (33a) or the controller (33b) of the linear drive is used as a distance sensor (40), and The linear drive (33a) or a controller (33b) of the linear drive determines the distance (13, 14).

4. The device according to claim 1, It is characterized in that The distance sensor (40) transmits the distance (13, 14) to a computer (41), and The computer (41) calculates the actual height (12) of the stack (10) based on the distance (13, 14).

5. The device according to claim 4, It is characterized in that The actual height (12) is compared with a setpoint height of the stack (10) with respect to deviations.

6. The device according to claim 4, It is characterized in that It is detected whether the actual height (12) is less than a predefined minimum height (15) of the stack (10).

7. The device according to claim 4, It is characterized in that The computer (41) calculates the actual weight of the stack (10) based on the actual height (12).

8. The device according to claim 7, It is characterized in that The computer (41) transmits the actual weight to the control device (25) of the robot (20), and the control device (25) takes the actual weight into account when implementing the robot movement (24).

9. The device according to claim 1, It is characterized in that The sensor (40) is designed as a proximity switch (40b) and is arranged on the gripping device (30) next to the stack (10) to be gripped.

10. The device according to claim 9, It is characterized in that The proximity switch (40) detects, based on its positioning, whether the actual height (12) is less than a predefined minimum height (15) of the stack (10).

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