Patent Application
20060263196
The invention concerns a device for removing a stack of flat products, in particular, of folding boxes, from a stacking device and disposing it in a bundling device, in particular, in a folding box manufacturing machine, wherein the stack, in the stacking device, is grasped by a gripper mounted to a robot arm, and is disposed in the bundling device.
DE 100 13 417 A1 discloses a method and a device for palletizing cardboard boxes. The cardboard boxes are thereby lifted off a transport means by a gripper which is mounted to a robot arm and are disposed on a bundling station. The robot is positioned between the transport means and the bundling station, and the robot arm is pivoted through 180° after grasping the pile to place the grasped stack on the bundling station. The bundling station comprises a Doppler station for grasping, lifting, and turning the deposited stack and optionally placing it onto another stack. It has turned out that a means of this type not only has a complex construction but also operates relatively slowly such that the stacks supplied by the robot arm cannot be conveyed as quickly as would be required by the material flow.
It is therefore the underlying purpose of the invention to further develop a device of the above-mentioned type such that high production speeds can be obtained.
This object is achieved in accordance with the invention by a device of the above-mentioned type in that a first stack grasped by the gripper and/or a subsequent second stack are turned as well as pivoted before being placed in the bundling device.
The inventive device has the essential advantage that the stacks are already oriented upon disposal in a manner which is required for further transport or for further processing e.g. tying up. The stack disposed by the robot arm must not subsequently be grasped and/or be turned by an additional unit to move it into the desired position. This not only increases the transport speed but also protects the product stack since it must be grasped less frequently, and therefore reduces mechanical interactions on the surface of the stacked, flat products.
In accordance with the invention, all stacks deposited by the gripper can be turned into a respective desired direction. However, rotation may also be restricted to only certain selected stacks.
In a further development, a subsequent stack is disposed onto a previously deposited stack, thereby forming higher stacks which then can be removed by the gripper e.g. from a stack shaft. In this variant, the previously deposited stacks need not be grasped and re-stacked. Stacking is already effected by the gripper such that the stack formed from several stacks can be further transported to be tied up without requiring further handling such as pivoting, stacking etc.
In a preferred method step, the first stack is rotated through +90° and the second stack is rotated through −90°. Alternatively, only the second stack is rotated through 180°. In this manner, the second stacks can be rotated through 180° relative to the first stack and disposed thereon. The stack produced in this fashion has the advantage that even when the flat products are not uniform, e.g. have a thick or high longitudinal side and a thin longitudinal side, such that the stacks have the shape of a prism instead of a cube, they have a substantially uniform and generally cuboid shape and can be immediately packaged after tying up.
They are preferably removed, turned and disposed in parallel planes, i.e. the stack is rotated about a vertical axis. In this manner, large and also heavy piles can be transported to the bundling device, thereby preventing the flat products, which form the stack, from being displaced and also avoiding exertion of excessive moments on the gripper.
In a further development, the second stack is rotated about a horizontal axis. The upper side of the stack is thereby turned downwards before being disposed in the bundling device. Sensitive surfaces of the flat products can e.g. thereby be turned inwards for protection.
In accordance with the invention, the stacking device has two removal planes for the stacks and the gripper removes the stacks from both removal planes. In one removal plane, a stack is formed by downward stacking and in the other removal plane a stack is formed by upward stacking, wherein both stacks are grasped by the gripper and can be disposed at the provided location in the bundling device. Separate gripping devices for upward and downward piled stacks are thereby required.
In accordance with the invention, during transport of the stack from the stacking device to the bundling device, the gripper performs a pivoting motion through an angle which is different from 180°. The stacking device and the bundling device need not be disposed in a straight line, one behind the other, rather can be arranged at an angle with respect to each other or be offset from each other. They may also be parallel and next to each other such that the gripper disposes the grasped pile parallel to the longitudinal axis of the stacking device. In this manner, the overall length of the production plant can be reduced.
The robot arm preferably receives a gripper which is adapted to the format of the folding box, wherein the respective gripper is disposed in a special magazine, thereby minimizing the set-up time.
Further advantages, features and details of the invention can be extracted from the following description which illustrates a preferred device with reference to the drawing. The features shown in the drawing and in the claims and description may be essential to the invention either individually or in arbitrary combination.
It should be emphasized that the stack 21 located in the stacking device 12 can be grasped by the gripper 18 irrespective of where it is stacked. If the folding boxes 19 are downwardly stacked, the finished stack 21 is provided in a lower region of the stacking device 12 to be dispatched, whereas a finished stack 21 which is stacked towards the top must be grasped in an upper region by the gripper 18. For grasping the stack 21, two prongs 26 of a gripper fork 28 underride the stack 21, and a holding-down device 30 is pressed onto the upper side of the stack 21. The stack 21 is thereby safely held such that the individual flat products 17 are not displaced during transport from the stacking device 12 to the bundling device 16. This is also ensured when the stack has a prismatic rather than a cuboid shape, in particular, for stacks of flat products 17 which have a substantially wedge-shaped cross-section with a thicker and a thinner end.
As is shown in
The finished stack 21 in the stacking device 12 is grasped and then supplied to the disposing table 24 through pivoting the robot arm 20. The gripping fork 28 is moreover rotated through +90° or −90° such that the stack 21 held by the gripper fork 28 is either oriented in accordance with arrow 42 or arrow 44. The stack 21 can then either be disposed directly on the disposing table 24 or on a previously deposited stack 21. This has the essential advantage that for prism-shaped stacks 21, a substantially cuboid stack can be formed through stacking two stacks 21 and can subsequently be transported from the disposing table 24 to a bundling station 46 in which a packet cord is tied around the stack.
It is, however, also feasible to position the first stack 21 on the disposing table 24 without turning it about the vertical axis 40, wherein the second stack 21 is then disposed on the first stack 21 after rotation through 180°.
In a further variant, the gripper fork 28 can be rotated about an axis which is orthogonal to the plane of the drawing of
In
The inventive method also permits forming stacks of prism-shaped stacks 21 without having to re-grasp and relocate the individual stacks 21 after disposal by the robot arm 20. As soon as the required number of stacks 21 has been piled on top of another, the finished stack can be bound in the bundling station 46.
