Method for lifting a material unit from a material arrangement

Abstract

A method for lifting individual material units (2) from a material arrangement (17), having the following steps: A) providing a material arrangement (17) made up of material units (2), B) providing a lifting mechanism (3) for lifting one of the material units (2) and positioning the lifting mechanism (3) on an application surface (16) at one of the corners (18, 19, 20, 21) of the material arrangement (17), wherein, proceeding from the corner (18, 19, 20, 21) in a longitudinal direction and in a widthwise direction, the application surface (16) does not extend over a distance longer than the width (b) of one material unit (2).

Description

[0001] Description

[0002] Method for lifting a material unit from a material arrangement

[0003] The present invention relates to a method for lifting a material unit from a material arrangement, in particular from a pallet. In particular, the material unit can be in bale form. The bale can have different dimensions in different directions, in particular a width direction and a length direction, when viewed from above onto the pallet. The material can be, for example, a raw polymer or a polymer blend of a rubber mixture.

[0004] In the processing of rubber compounds, raw polymer bales are placed on pallets. The pallets can have different dimensions and designs. The bales are usually removed from the pallet one after the other by a gripper system. This requires position detection of each bale. However, position detection is difficult because the bales are often wrapped in film that overhangs the sides. In addition, the environment during material processing is often dirty and dusty.

[0005] To ensure smooth, fully automated operation, however, reliable bale position detection is essential. For this reason, optical systems are sometimes used, but these are expensive and often unreliable. Optical solutions such as 3D cameras or laser measurements reach their limits here. Alternatively, the bales are removed manually. This is hard physical labor and prone to errors.

[0006] It is an object to provide an improved method for lifting individual material units from a material arrangement.

[0007] In a method for lifting individual material units from a material arrangement, a material arrangement of material units is provided. The material units are, for example, cuboid-shaped. They are, for example, bales of raw polymer or a polymer mix of a rubber mixture. The material units can be arranged on a pallet. In particular, the material units can be arranged on top of one another in several layers. Each layer can have a dense packing pattern of the material arrangement.

[0008] In a top view, the material arrangement has a length along a longitudinal direction, a width along a width direction and a plurality of corners. In a top view, each of the material units has a length and a width, where the width is less than or equal to the length. The material units can be packed closely together in a layer and completely fill a pallet in the length and width directions. The material units are arranged in their length or width direction in particular parallel or perpendicular to the length of the material arrangement and / or a pallet.

[0009] In the method, a lifter is provided for lifting one of the material units. The lifter is designed, for example, as a vacuum lifter having a vacuum plate.

[0010] The vacuum plate, for example, has a hard sealing edge to form a sealing contact with the material unit. The sealing edge can be designed to be razor-sharp for cutting into the material unit. It has been found that an improved adhesive force can be achieved by making an incision compared to pressing the sealing edge into the material unit. The material units can also each have packaging. The sealing edge can be designed such that the packaging is completely or partially severed when the material units are attacked.

[0011] The material of the sealing edge is particularly hard than the material of the material unit to be lifted, so that the material of the sealing edge is not deformed or is only slightly deformed when cutting into the material unit. The vacuum plate therefore does not have a soft rubber seal to establish contact with the material unit.

[0012] The lifter is applied to an engagement surface at one of the corners of the material arrangement in such a way that the engagement surface, starting from the corner, extends along the longitudinal and width directions for a distance no longer than the width of a material unit. This is particularly the case at an outer corner of the material arrangement.

[0013] This ensures that only a single material unit is gripped for all packing patterns, without the need to identify the specific packing pattern. Due to the corner positioning, the material units are lifted eccentrically if the length of the material unit is greater than the width. The lifter must therefore apply a sufficiently large lifting force. It is also possible to use a lifter other than the vacuum lifter described above, as long as a sufficiently large lifting force can be applied.

[0014] After lifting a unit of material, the lifter can be positioned at another corner, choosing the attack surface as in the previous step. For example, the material arrangement has four corners, and the steps are performed sequentially at all four corners. In a densely packed material arrangement, the corners can correspond to the corners of the pallet.

[0015] It is also possible that the material arrangement of the respective layer is not originally tightly packed and therefore has fewer or more than four outer corners or the corners do not correspond to the corners of the pallet. In this case, for example, a sensor can be used to detect whether a material unit is present at each corner in this layer and then only the material units actually present in this layer can be lifted at the corners. An empty corner can also be detected by placing a lifter at the corner of the pallet in the plane of the respective layer and can be detected by the then lack of lifting force or a lack of negative pressure with a vacuum lifter.

[0016] It is also possible, after removing a first material unit at a corner, to move to one of the corners of the incomplete material arrangement that has been newly formed by removing the material unit. This does not have to be a corner of the pallet or the original material arrangement.

[0017] The position of a corner can be easily detected, for example, using a sensor based on the height difference to a lower layer or the floor.

[0018] The position of a corner can be easily detected, for example, using a sensor based on the height difference to a lower layer or the floor. It is also possible to detect the orientation of a lifted material unit when lifting a material unit, thereby determining the position and / or orientation of further material units. For example, light barriers, lasers, mechanical sensors, weight distribution on the lifter, or similar technologies can be used for this purpose.

[0019] For example, all material units at the corners are first removed as described above, and then the position of the remaining material units is detected. This is easily achieved after removing material units at the corners, as a height difference to the underlying layer or the floor can now be detected. For example, optical sensors, ultrasonic sensors, infrared sensors, capacitive sensors, magnetic sensors, or tactile sensors can be used for this purpose.

[0020] The present invention encompasses several aspects, in particular devices and methods. The features, properties, and embodiments described for one of the aspects are intended to apply accordingly to the other aspect.

[0021] Furthermore, the description of the objects specified here is not limited to the specific embodiments.

[0022] Rather, the characteristics of the individual embodiments

[0023] - as far as technically feasible - be combined with each other.

[0024] In the following, the objects described here are explained in more detail using schematic examples.

[0025] It shows :

[0026] Figure 1 shows a pallet for providing material units in material processing in a perspective view,

[0027] Figures 2a-2k show possible packing patterns of material units in a material arrangement in top view,

[0028] Figure 3 shows a lifter for lifting a material unit in a schematic sectional view,

[0029] Figure 4 shows a lifter lifting a material unit in a schematic sectional view,

[0030] Figure 5 shows a material unit with an attack surface for a jack in a perspective view,

[0031] Figure 6 shows a perspective view of a lifter engaging a material unit,

[0032] Figures 7a to 7f show process steps when lifting a material unit with a view from above onto a material arrangement,

[0033] Figure 8 shows a positioning of the lifter in process steps 7e and 7f in a perspective view according to an embodiment,

[0034] Figures 9a-9k show a schematic diagram of a method for lifting a material unit with different packing patterns in a top view.

[0035] Preferably, in the following figures, the same reference numerals refer to functionally or structurally corresponding parts of the various embodiments.

[0036] Figure 1 shows a pallet 1 for providing material units in material processing. For example, the material units can be in the form of bales. The bales can be cuboid-shaped. These are, for example, rubber bales for rubber processing.

[0037] The pallet 1 has a height H, a width B and a length L. Width B and length L are the dimensions of the pallet 1 when viewed from above, i.e. looking in the direction of gravity, in particular towards the bottom of the pallet 1 on which the material units lie. A pallet 1 with side walls is shown here. It is also possible to use a pallet 1 without side walls. It is also possible for the material units to be arranged directly on the floor. The pallet 1 serves to provide a large number of material units 2 which are stacked, for example, in several layers and lie close together in each layer. The top side of each layer is in particular at a uniform height. There can also be just one layer. The material units 2 can completely fill the pallet 1 in terms of width B and length L. It is also possible for the material units 2 to incompletely fill the pallet 1.

[0038] Figures 2a to 2k show possible packing patterns for a layer of material units 2 in a top view of a loaded pallet, such as pallet 1 from Figure 1. The material units 2 are stacked on top of one another in the pallet 1 and lie close to one another within one layer of the stack. For example, six layers of six material units 2 each are stacked on top of one another. The material units 2 do not overlap within one layer.

[0039] The material units 2 each have a length 1 and a width b when viewed from above onto the pallet 1, whereby length 1 and width b can be different. In this case, the length 1 is greater than the width b. In this case, six material units 2 can be stacked closely together in one stacking level. The material units 2 arranged next to and on top of one another form a material arrangement 17 whose length L and width B correspond to the length L and width B of the pallet 1. The material units 2 therefore fill the space within the pallet 1 as well as possible. It is also possible for the material arrangement 17 not to be arranged on a pallet, for example directly on the floor. The length 1 of a material unit 2 is in this case half the length L of the material arrangement 17 or of the pallet 1. The width b of a material unit 2 is in this case one third of the width B of the material arrangement 17.However, other width and length ratios are also possible.

[0040] The material units 2 can be arranged densely in or on the pallet 1 in the eleven packing patterns shown here.

[0041] For further processing, the material units 2 are to be lifted individually from or off the pallet 1, for example, in a plant and transported to a processing device and deposited there. For example, bales are to be placed from the pallet 1 onto a feed conveyor for processing, for example, in an internal mixer.

[0042] Such bales, for example, have dimensions ranging from 500 mm x 300 mm x 100 mm to 800 mm x 400 mm x 250 mm (L x W x H). The weight of one bale, for example, is in the range of 35 kg. However, several bales may stick together during delivery, so considerable forces (>400 kg) are required to lift the bales.

[0043] To remove the material units 2, it is usually necessary to know the packing pattern in order to be able to remove the material units 2 individually. Due to the tight fit of the material units 2 against one another, a relatively complex optical system has been necessary.

[0044] Figure 3 shows a lifter 3 for removing individual material units 2 from or from the pallet 1. This is a vacuum lifter comprising a vacuum plate 4 with an outlet 5 for extracting air from a cavity 6. The outlet 5 is arranged in a wall 7 of the vacuum plate 4. The vacuum plate 4 can be attached to a lifting arm 8 on its upper side.

[0045] The vacuum plate 4 has a hard sealing edge 9. In particular, the sealing edge 9 can be razor-sharp. The sealing edge 9 can be an integral component of the wall 7 which encloses the cavity 6 and in which the outlet 5 is formed. In order to compensate for unevenness of the material unit 2, the vacuum plate 4 is pressed so firmly against the material unit 2 that the sealing edge 9 is in complete contact with the surface of the material unit 2 all around. In particular, the sealing edge 9 can cut into the material unit 2 and, for example, sever fibers of the material. A vacuum pump 10 is connected to the outlet 5 of the vacuum plate 4 to generate a vacuum.

[0046] The vacuum plate 4 can, for example, be combined with a robot or crane as the last element of a kinematic chain (“end effector”).

[0047] The lifter 3 can have a pressing device 11 for pressing the vacuum plate 4 onto the material unit 2 after it has been placed on the material unit 2. By applying a force from above onto a holder 12, the pressing device 11 exerts a force from above onto the vacuum plate 4.

[0048] In addition, the lifter 3 can have a push-off device 13 in order to release the material unit 2 after it has been placed down and, for example, the vacuum of a vacuum lifter has been removed.

[0049] For example, a push-off device 13 can be formed by lateral projections that can be pressed downward relative to the vacuum plate 4. For example, the projections are arranged on the holder 12 so that they can be displaced downward and can be automatically displaced downward to exert a force on the material unit.

[0050] Alternatively, pressing and / or detaching can also be performed entirely manually. The lateral projections can also be provided solely for lateral positioning of the vacuum plates 4 and not provide a pressing function.

[0051] Figure 4 shows a lifter 3 in the form of a vacuum lifter lifting a material unit 2. Before a vacuum is generated, the vacuum plate 4 is pressed against the material unit 2 in such a way that the sealing edge 9 cuts into the material unit 2 all the way around, either partially or completely. Thus, for example, fibers of the material unit 2 are severed.

[0052] For example, beneath the material unit 2 there is a lower material unit 15 which adheres to the material unit 2. Thus, during the lifting process, a greater force must be provided in order to separate the material units 2, 15 from one another. In the process, the material unit 2 first detaches from the underlying material unit 15 in a central area, so that a deformation occurs compared to an outer area. As a result, some of the material on the outside of the sealing edge 9 detaches, which, however, is not detrimental to the sealing effect on the inside of the sealing edge 9 because the sealing edge 9 cuts into the material. The sealing edge 9 has a shape which promotes a close fit on the inside.

[0053] Thus, with the lifter 3 shown, a significantly higher force than the pure weight of the material units 2 can be applied, so that even several material units 2, 15 adhering to one another can be detached from one another.

[0054] In addition, Figure 4 shows an outer packaging 14, for example in the form of a film, which is completely severed by the sealing edge 9. The packaging 14 is shown, for example, only on the upper side of the material unit 2, but it can completely surround the material unit 2. A packaging 14 can also be arranged around the lower material unit 15.

[0055] For example, before the vacuum is generated, a force is applied from above to the vacuum plate 4 in the direction of the material unit 2. The force is, for example, up to 2000 N. The minimum and maximum force depends in particular on the deformability of the material unit.

[0056] As soon as the material unit 2 rests against the sealing edge 9 all around, a vacuum can be created by sucking the air out of the cavity 6. The vacuum plate 4 adheres to the material unit. As soon as a sufficient vacuum level and thus holding force is reached, the material unit 2 can be lifted.

[0057] To deposit the material unit 2, the vacuum plate 4 is ventilated and the vacuum released. If the material unit 2 is still attached to the vacuum plate 4, the connection can be released manually or via a mechanical release device 13.

[0058] The wall 7 can have the dimensionally stable sealing edge 9 as an integral component. Thus, the sealing edge 9 is not attached to a housing part of the vacuum plate 4, but rather forms the lower edge of the wall 7. The sealing edge 9 can be made of, for example, steel, hard plastic, or another sufficiently hard material. The material of the sealing edge 9 should not deform, in particular when pressed against the material unit 2, but rather cause an incision in the material unit 2.

[0059] Different geometries of the vacuum plate 4 and the sealing edge 9 are possible. For example, the vacuum plate 4 has a circular, rectangular, square, triangular, hexagonal or generally polygonal circumference. A vacuum lifter can also have several vacuum plates 4. The holding force of the vacuum lifter can be adjusted in particular via the base area of ​​the vacuum plate 4 enclosed by the sealing edge 9, via the quality of the vacuum, and via the number of vacuum plates 4.

[0060] The wall thickness of the sealing edge 9 decreases towards the bottom. "Downwards" here means in the direction of the opening of the vacuum plate 4, i.e. usually in the direction of gravity, "upwards" in the opposite direction. The sealing edge 9 tapers to a point towards the bottom. In this way, the sealing edge 9 can cut particularly well into the material unit 2. The sealing edge 9 is designed to be razor-sharp. In this way, the vacuum plate 4 can also cut into a material unit 2 provided with a packaging 14 in such a way that the packaging 14 is completely severed and the sealing edge 9 lies directly against the inner material unit 2.

[0061] In Figure 4, the sealing edge 9 is beveled on one side, i.e., chamfered. The slight inclination of the outer side of the sealing edge 9, together with the razor-sharp sealing edge 9, enables a good cut into the material unit 2. The greater inclination of the inner side ensures that the material unit 2 lies tightly against the inner side and is also slightly compressed by the sealing edge 9, thus improving the sealing effect. The seal is thus achieved by the material within the vacuum plate 4.

[0062] By cutting the sealing edge 9 into the material, it is also achieved that the material inside the vacuum plate 4 is partially mechanically decoupled from the material outside the vacuum plate 4, so that deformation of the material outside the vacuum plate 4 does not lead to detachment of the inner material from the sealing edge 9. The sealing effect is thus maintained, even if the outer material is deformed during lifting due to the force of weight or due to adhesion to underlying material units 2.

[0063] The sealing edge 9 can have different cutting geometries, for example, a straight or sawtooth-shaped geometry. Such a lifter 3 can also have several vacuum plates 4 attached to a common lifting arm 8.

[0064] Due to the good sealing effect, a holding force of approximately 500 kg is possible, so that even material units 2 that are stuck together, such as bales or skins, can be lifted.

[0065] Furthermore, due to the high holding force, it is not necessary for the lifter 3 to be placed centrally on a material unit 2. For example, it is sufficient for the lifter 3 to engage an engagement surface 16 that, viewed in the longitudinal direction, does not extend beyond half the length 1 of the material unit 2. Thus, the material unit 2 can be lifted, in particular, with less than half its length. This allows the material unit 2 to be lifted eccentrically. This also has the advantage that the material unit 2 detaches on one side due to the eccentric gripping, thus reducing the lifting force.

[0066] Figure 5 shows an engagement surface 16 for a lifter 3, which allows lifting of the material unit 2. The engagement surface 16, for example corresponding to the base area of ​​a vacuum plate 4, does not extend beyond half the length 1 of the material unit 2, as seen from a corner 23.

[0067] Figure 6 shows an example of an eccentric attachment of a lifter 3 to the material unit 2. The contact surface 16 is located only in an area which, viewed in the longitudinal direction, does not extend over the center of the material unit 2.

[0068] Regardless of the length and width ratios of the material unit 2, the engaging surface 16 should not extend from a corner 23 of the material unit 2 along a longitudinal direction and along a width direction over a distance greater than the width b of the material unit 2. In this way, it can be ensured that even with different positions of the material unit 2, only a single material unit 2 can be removed from the material arrangement 17 without knowing the exact packing pattern.

[0069] Figures 7a to 7f show steps of a method for lifting individual material units 2 from a pallet 1 by means of a lifter 3, for example by means of the previously described vacuum lifter with a particularly high holding force.

[0070] According to Figure 7a, the lifter 3 is first positioned in the area of ​​one of the corners 18, 19, 20, 21 of the material arrangement 17, and a lifting operation is carried out. These are always outer corners. Positioning at the corner 18 is possible with a simple optical system, since the outer contour of the material arrangement 17 or the pallet 1 can be easily recognized or is defined by solid walls.

[0071] The lifter 3 only engages an engagement surface 16 which, in the longitudinal and width directions of the material arrangement, does not extend over a distance longer than the width b of a material unit 2. Thus, for all packing patterns, the lifter 3 automatically only engages a single material unit 2, so that only one material unit 2 is lifted. This is shown in Figures 9a to 9k for all packing patterns and for all corners 18, 19, 20, 21. In Figure 7b, one of the material units 2 has now been removed from the material arrangement 17 at a corner 18. The lifter 3 is then positioned such that it engages another corner 19 of the material arrangement 17 and thus lifts out another of the material arrangement 17.

[0072] This is repeated in steps 7c and 7d for the additional corners 20, 21. The corners 18, 19, 20, 21 refer, for example, to the corners of the original material arrangement 17 with a complete packing pattern. However, it is also possible to remove the material units 2 at any corner of an incomplete material arrangement 17. It is also possible to use a hold-down device to hold down additional material units when lifting the material unit 2.

[0073] Thus, with the method used here, the four material units 2 arranged at the corners 18, 19, 20, 21 can be lifted out individually without detecting the packing pattern.

[0074] In Figure 7e, the lifter 3 is positioned at one of the remaining material units 2. The position of the two remaining material units 2 can be easily determined using a simple optical system due to the height differences now existing relative to the underlying level or the ground.

[0075] For example, light barriers, lasers, mechanical sensors, a weight distribution on the lifter 3 or similar technologies can be used for this purpose. For example, as shown in Figure 8, the position of three adjacent side surfaces is determined by one or more sensors 22. By detecting the weight distribution, the orientation of the material unit 2 and thus the orientation of the remaining material units can be determined. Thus, the arrangement of the material units 2 does not have to be detected in the full position using complex camera technology, but can be determined when individual material units 2 are lifted. The lifter 3 can then be applied eccentrically (Figure 8) or centrally (Figure 7e) to the surface of one of the remaining material units 2.

[0076] As shown in Figure 7f, the last material unit 2 is then lifted out in the same manner as in Figure 7e. If the material arrangement 17 comprises several levels stacked one above the other, the procedure for the level below can be as shown in Figures 7a to 7f.

[0077] The process described here makes it possible to remove individual material units from a densely packed pallet in a cost-effective manner. The process is particularly robust and reliable, as the position of the individual material units does not require complex optical detection. It can also be a redundant system if the packing pattern is detected using a combination of mechanical and optical detection. Reference symbol

[0078] 1 pallet

[0079] 2 material units

[0080] 3 lifters

[0081] 4 vacuum plates

[0082] 5 Outlet

[0083] 6 cavity

[0084] 7 Wall

[0085] 8 lifting arm

[0086] 9 Sealing edge

[0087] 10 Vacuum pump

[0088] 11 Pressing device

[0089] 12 Bracket

[0090] 13 Pressing device

[0091] 14 Packaging

[0092] 15 lower material unit

[0093] 16 attack area

[0094] 17 Material arrangement

[0095] 18 Corner material arrangement / pallet

[0096] 19 Corner material arrangement / pallet

[0097] 20 Corner material arrangement / pallet

[0098] 21 Corner material arrangement / pallet

[0099] 22 Sensor

[0100] 23 Corner material unit

[0101] B Width material arrangement / pallet

[0102] L Length of material arrangement / pallet

[0103] H Height of material arrangement / pallet b Width of material unit

[0104] 1 Length Material unit h Height Material unit

Claims

Patent claims 1. A method for lifting individual material units (2) from a material arrangement (17), comprising the steps: A) Providing a material arrangement (17) of material units (2), wherein, viewed from above onto the material arrangement (17), the material arrangement (17) has a length (L) along a longitudinal direction, a width (B) along a width direction and a plurality of corners (18, 19, 20, 21), wherein each of the material units (2) has a length (1) and a width (b), wherein the width (b) is less than or equal to the length (1), B) Providing a lifter (3) and attaching it to an engagement surface (16) at one of the corners (18, 19, 20, 21), wherein the engagement surface (16) extends from the corner (18, 19, 20, 21) along the longitudinal direction and along the width direction not over a distance longer than the width (b) of a material unit (2).

2. Method according to claim 1, wherein, in order to lift another of the material units (2), steps A) and B) are repeated, the lifter (3) acting on another of the corners (18, 19, 20, 21) of the material arrangement (17).

3. Method according to one of the preceding claims, in which the material arrangement (17) has four corners (18, 19, 20, 21) and steps A) and B) are repeated successively at the four corners (18, 19, 20, 21).

4. Method according to one of the preceding claims, in which, after lifting at least one material unit (2), the position of another of the material units (2) is detected by means of a sensor (22).

5. Method according to one of the preceding claims, wherein when lifting at least one of the material units (2) the orientation of the material unit (2) is detected by means of a sensor (22).

6. Method according to one of the preceding claims, wherein the width (b) of the material units (2) is smaller than the length (1).

7. Method according to one of the preceding claims, in which the engagement surface (16) does not extend over a center of the material unit (2) in the longitudinal direction.

8. Method according to one of the preceding claims, in which the material units (2) are arranged on a pallet (1) with or without side walls.

9. Method according to one of the preceding claims, in which the material units (2) are arranged with their length (l) and width (b) respectively parallel or perpendicular to the length (L) of the material arrangement (17).

10. Method according to one of the preceding claims, in which, before generating a vacuum, the vacuum plate (5) is pressed against the material unit (2) so that the sealing edge (9) at least partially cuts into the material unit and forms a sealing contact with the material unit (2).

11. The method according to claim 10, wherein the sealing edge has a straight, sawtooth-like or serrated cutting geometry.

12. Method according to one of claims 10 or 11, wherein the material unit (2) comprises a packaging (14), wherein the sealing edge (9) cuts through the packaging (14).

13. Method according to one of the preceding claims, in which the material units (2) are formed as bales or skins of a rubber mixture in the material processing for the rubber industry.

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