GB2265352A

GB2265352A - Gripper apparatus

Info

Publication number: GB2265352A
Application number: GB9305942A
Authority: GB
Inventors: Kurt Schmalz
Original assignee: J Schmalz GmbH
Current assignee: J Schmalz GmbH
Priority date: 1992-03-24
Filing date: 1993-03-23
Publication date: 1993-09-29
Anticipated expiration: 2013-03-23
Also published as: GB9305942D0; GB2265352B

Abstract

Gripper apparatus for gripping by suction and raising discrete articles in the form of one or more objects has a suction box (2) which can be placed on the discrete articles and which can be connected to a reduced pressure apparatus and which has on its side edges air-impermeable curtains (4). Simple manipulation of the discrete articles is achieved in that the position of at least one curtain (4) of a side edge is alterable horizontally and/or vertically especially by means of actuators 13. Preferably the actuators are operated together by a central, star-shaped drive. Preferably the vacuum for individual articles is controlled by rakes with push rods opened by the presence of an article. … <IMAGE> …

Description

1 Title: Gripper apparatus 2265352 9 The invention relates to a gripper

apparatus for gripping, in narticular bv suction and raising discrete articles. the apparatus having a suction box which can be placed on the discrete articles, which can be connected to a reduced pressure apparatus and which has on its side edges air- impermeable curtains.

Such a gripper apparatus is known for example from DE 29 21 005 Al, and serves for handling cartons, packages. etc. This known gripper apparatus has a suction box which is placed on the object or objects which represent the discrete articles. The interior of the suction bo is subjected to a reduced pressure by way of the reduced pressure apparatus so that the discrete articles, which, as mentioned above, may comprise one or more objects, are attracted by suction. For lateral sealing, the suction box has curtains which bear against the discrete articles. Using this gripper apparatus the discrete articles can be raised and manipulated without problems. It has proved to be disadvantageous that the size of the suction head, which is generally constructed to be rectangular, has to be adapted to the size of the discrete articles to be manipulated, since otherwise the curtain cannot bear laterally against the side walls of the discrete articles and cannot seal the gripper apparatus against infiltrated air. Thus, a plurality of differently constructed gripper apparatus are required in order to be able to manipulate objects of all types.

The object of the invention is thus to construct a gripper apparatus with which discrete articles of differing dimensions can be manipulated without problems.

According to the invention there is provided gripper apparatus for gripping, in particular by suction, and raising discrete articles in the form of one or more objects, the apparatus having a suction box which can be placed on the discrete articles, which 2 can be connected to a reduced pressure apparatus and which har? on its side edges air-impermeable curtains, wherein the position of at least one curtain (4) of a side edge can be altered horizontally and/or vertically.

As a result of altering the horizontal and/or vertical position or length of at least one curtain of the side edge, it becomes possible for the width of the surface of the gripper apparatus receiving discrete articles and/or the height to be adapted to the dimensions of the discrete articles. In this way, objects of differing dimensions can be gripped and raised without gripper apparatus adapted thereto having to be used, since the gripper apparatus according to the invention is adapted to different sizes by the displacement of the curtain. This curtain is displaced until it bears against the side surface of the object to be raised and externally seals the suction box.

Further advantages, features and details of the invention will emerge from the remaining claims and the description which follows, in which particularly preferred embodiments are described in detail with reference to the drawings, in which:

Figure 1 is a schematic view of a gripper apparatus according to the invention, in longitudinal section; Figure 2 shows a view in the direction of the arrow II of Figure 1, of the underside of the gripper apparatus; Figure 3 shows a schematic view of a further embodiment of a suction box equipped with an apparatus producing f low resistance, in longitudinal section; and Figure 4 shows a plan view of the embodiment of Figure 3.

Figure 1 shows a gripper apparatus, generally designated 1, which uses suction to attract and raise packages, cartons, sacks, cans, etc. The gripper apparatus 1 has a suction box 2 to which a 3 reduced pressure hose 3 is fixed. This reduced pressure hose 3 is connected to a reduced pressure apparatus (not shown) by way of which the interior of the reduced pressure hose 3 and the interior of the suction box 2 are subjected to a reduced pressure. Provided at the underside of the suction box 2 are curtains 4 which are connected to the suction box 2 only by their upper edge. The curtains 4 are made for example from a flexible material such as silicone or other synthetic material. and have a thickness of 0.5-5 mm, in particular 1 mm. The curtains 4 can also be constructed as telescopable plates which can be pushed into one another or drawn out of one another. The plates can be of metal or synthetic material. The suction box 2 has a rectangular base area which is slightly larger than the Euro-pallet size of 800 mm x 1200 mm. This ensures that the suction box 2 can be placed with reliability on a palletized layer 19 of discrete articles such that the lateral curtains 4 reach around the side walls 18 of the layer 19 of discrete articles. The uppermost layer 19 of discrete articles is located in the interior of the suction box 2, when the latter is placed on it. If a reduced pressure is produced by means of the reduced pressure pparatus, the uppermost layer 19 of discrete articles is attracted by suction by the suction box 2. Moreover, the curtains 4 bear against the side surfaces 18 of the layer 19 of discrete articles and thus externally seal the interior of the suction box 2, so that a reduced pressure can be developed in the interior of the suction box 2.

Figure 1 also shows a ventilation flap 5 in a closed position. A central drive 6 is also shown, by means of which the horizontal position of the curtains 4 can be altered. The reduced pressure hose 3 is attached to a suction connection piece 7 connected to the housing of the suction box 2. Within the suction connection piece 7 there is a suction f lap 8 which takes up an open position. To the side of the housing of the suction box 2, there are provided drives 9 for pallet gripping fingers 10 by means of which empty pallets can be gripped and also raised by means of the gripper apparatus 1. In the interior of the suction box 2 4 there is located, below the central drive 6, a star-shaped drive 11 which is shown more clearly in Figure 2. Manipulators 13 by means of which the curtains 4 can be moved horizontally are secured to this star-shaped drive 11 by means of pins 12. These curtains 4 and the end of the manipulators 13 facing the curtains 4 are mounted in guiderails 14 which ensure parallel displacement of the curtains. Moreover, the curtains 4 are suspended rotatably or pivotally so that they are pivotal about a vertical axis 22. The manipulators 13 are essentially composed of a housing 15 and a tie rod 16, and between the housing 15 and the tie rod 16 there is a spring element 17 which is biassed to draw the tie rod 16 into the housing 15. As a result of rotation of the star-shaped drive 11, the curtains 4 are applied to the side surfaces 18 of the layer 19 of discrete articles, which in this embodiment comprises a plurality of objects, e.g. cartons, such that the curtains 4 bear against the side surfaces 18 under the force of the spring elements 17. It can furthermore be seen that the layer 19 of discrete articles is not arranged centrally below the suction box 2 but is offset laterally. This lateral of f set is compensated by correspondingly displacing the curtains 4, the left-hand curtain 4 being displaced less far than the right-hand curtain 4.

Also visible in Figure 1 is a reinforcing frame 25, the underside of which is formed by a perforated metal sheet 24. An apparatus 26 producing flow resistance is inserted in this reinforcing frame -25 and is held on its rear side by a grid framework 27. The apparatus 26 producing flow resistance is, in the embodiment illustrated in Figure 1, an open-cell foam material which is divided into a plurality of individual bodies 28. The individual bodies 28 lie next to one another and fill the entire interior of the reinforcing frame 25. By means of suitable apparatus. the foam material can be compressedr as a result of which the flow resistance is adjustable to a desired amount. As a result of the apparatus 26. there is provided the advantage that, if there are blank positions below the perforated metal sheet 24. that is to say at positions in the perforated metal sheet 24 against which there bears no object to bp attracted by suction, the apparatus 26 offers a flow resistance to the air to be attracted by suction, so that the vacuum in the suction box 2 does not abruptly diminish or even collapse via these blank positions. In this way, relatively large areas not covered by objects can be accepted on the perforated metal sheet 24, since the vacuum in the suction box can be maintained by means of the flow resistance of the apparatus 26.

a As a resuit of the foam material, which increases the flow resistance, relatively large blank areas in the layer of discrete articles can be accepted, or relatively heavy objects can be raised at given blank areas.

Figure 2 represents in solid lines the starting position of the individual elements and in broken lines the working position, in which the curtains 4 bear against the side walls 18 of the layer 19 of discrete articles. The dot-and-dashed line represents the axis of the pallet gripping fingers 10, which are illustrated in the outward pivoted and inward pivoted (dashed) positions. The curtains 4 are suspended on a beam 20 which is connected to the manipulator 13 and the guiderail 14. By turning the star-shaped drive 11 the curtain 4 is displaced by the manipulator 13 in the direction of the axis of the guiderail 14 until the curtain bears against the side surface 18 of the layer 19 of discrete articles. On turning the star-shaped drive 11 further in the direction of the arrow 21, the tie rod 16 is withdrawn from the housing 15 and the spring element 7 is thus compressed. This spring force is transmitted to the pressure beam 20 and thus to the curtain 4, which now bears with this spring force against the side surface 18.

If the side surface 18 is not parallel to the direction of the beam 20, the latter can be adapted to the oblique position of the side surface 18 by being turned about the axis 22, so that the curtain 4 is once again in a sealing position. When all four curtains 4 bear against the side surfaces 18 of the layer 19 of 1 6 discrete articles, the layer 19 of discrete articles can be raised from the layer beneath and centred. During this, the entire layer 19 moves within the suction box 2 in the direction of the arrow 23. Another possibility for centring consists in the suction box 2 being moved, in this case in opposition to the direction of the arrow 23 and consequently aligning itself with respect to the position of the layer 19 of discrete articles.

Advantageously. the suction box 2 is suspended resiliently, so that even layers 19 of discrete articles which have oblique surfaces or are stacked obliquely can be gripped. Preferably, the central drive 6 is an electric motor, although a pneumatic adjustment of the curtains 4 is also possible. In this embodiment, the manipulators 13 are constructed as pneumatic cylinders. By means of path and angle measurement elements which are provided on the manipulators 13 or on the axes 22, it is possible after bringing the curtains 4 to bear against the side surfaces 18 of the layer 19 of discrete articles to determine the position thereof with respect to the suction box 2. This has the advantage that, after gripping the layer 19 of discrete articles, it can be deposited in a precise position and palletized exactly. Furthermore, the vertical length of the curtains 4 is adjustable,, so that it is also possible to attract by suction and to raise two or more layers 19 of discrete articles. These curtains 4 then bear against the side -surf aces 18 of the layer 19 of discrete articles lying one above the other. The layers 19 of discrete articles attracted by suction bear against the f low resistance apparatus 26, which is for example constructed as a perforated metal sheet 24 and which forms an abutment surface.

Furthermore. an apparatus for altering the suction pressure is provided which can be used to adjust the suction pressure and to match it to the particular layer 19 of discrete articles to be raised. As a result. it becomes possible to raise layers 19 of discrete articles of different weight without the layer underneath being attracted by suction as well. For this purpose, the apparatus altering the pressure of attraction by suction has 7 for example a storage unit in which data representative of thp pressure of attraction by suction required as regards the size, weight, nature and so on of the layer 19 of discrete articles to be attracted by suction can be entered and stored. After the layer 19 of discrete articles has been attracted by suction, for example with a low pressure of attraction by suction, and raised slightly. the pressure of attraction by suction can be increased to its maximum intensity and the layer of discrete articles raised further and transported away. As a result of this, it becomes possible to raise layers of discrete articles with or without intermediate partitions, which as a rule are of cardboard. Moreover, it is also possible to grip and raise these intermediate partitions separately. In that case, the curtains are offset to their innermost position. the suction box 2 is placed on the intermediate partition, and the intermediate partition is gripped and raised.

Preferably, the invention has a control circuit for the pressure prevailing in the gripper. For this purpose, a pressure measurement element is provided which determines the pressure prevailing in the gripper and, as a function of a pressure difference with regard to a pressure reference value, controls an infiltrated air flap, in particular by way of a proportional valve. In this way the gripper pressure is constantly re-adjusted.

Figures 3 and 4 show a further embodiment of the flow resistance apparatus 26, which in this case comprises a plurality of individual flow valves 29. Each flow valve 29 comprises a valve ring 30 in which a valve piston 31 is movably guided. The valve ring 30 is provided with four overflow channels 32 which open out radially, approximately at half the axial height, into the interior of the ring and axially upwardly, that is to say on the side opposite the perforated plate 24. The piston 31 is arranged in the valve ring 30 such that in its rest position, illustrated at I, it covers the overflow channel 32, and in its open position II is free of the channel 32. Moreover, the valve 8 piston 31 is provided with a tappet 33 which passes through the,. perforated plate 24 by way of correspondingly sized cutouts 34. Thus, in the rest position I of the piston 31, the tappet 33 projects into the receiving space for the layer 19 of discrete articles (Figure 1). If the suction box 2 is placed on a layer 19 of discrete articles, the tappets 33 are pressed in by the objects to be attracted by suction, as a result of which the piston 31 releases the channel 32 and air can be removed by suction by way of the channel 32 and the apertures 34. If there is no object under one or more tappets 33 then the tappet 33 remains in its extended position, so that the channel 32 remains closed by the piston 31 and thus no air is removed by suction in this region. A relatively large flow cross-section forthe air to be removed by suction is achieved by each flow valve 29, or each valve ring 30, having four channels 32 and the piston 31 being provided at its lower peripheral edge with a recess or if appropriate with a chamfer, as a result of which the flow resistance is reduced to a minimum. Moreover, the piston is provided on its end side facing the perforated metal sheet 24 with a seal 35 by way of which some of the holes of the perforated metal sheet 24 are closed in the rest position I-of the piston 34. The space 36 behind the piston 31 is also closed with respect to the suction box 2 by way of a seal 37, so that the piston 31 is not attracted by suction by the vacuum in the suction box 2 unless an object bears against the tappet 33. In order to ensure that the same pressure prevails in this space 36 as in the region of the layer 19 of discrete articles, the tappet 33 has a central axial bore 37 which connects the space 36 to the surroundings.

Using the apparatus 26 illustrated in Figures 3 and 4, double-lifting when depalletizing is avoided, that is to say on raising the uppermost layer of discrete articles the possibility that individual objects from the layer of discrete articles underneath are also taken at positions where the upper layer of discrete articles has blank positions is prevented. As a result of the individual flow valves 29, the stream of leakage air is 9 reduced to a minimum, so that a considerable vacuum can always be maintained.

1

Claims

1. Gripp6r apparatus for gripping, in particular by suction, and raising discrete articles in the form of one or more objects, the apparatus having a suction box which can be placed on the discrete articles, which can be connected to a reduced pressure apparatus and which has on its side edges air-impermeable curtains, wherein the position of at least one curtain of a side edge can be altered horizontally and/or vertically.

2. Gripper apparatus according to Claim 1, wherein the curtain is mounted such that it is displaceable and/or rotatable and/or pivotal.

3. Gripper apparatus according to Claim 1 or 2. wherein, when the gripper apparatus is placed on the discrete articles to be gripped, the curtains can be offset such that they bear laterally against the discrete articles.

4. Gripper apparatus according to one of the preceding claims, wherein the discrete articles can be offset with respect to the gripper apparatus by way of the curtains.

5. Gripper apparatus according to one of the preceding claims, wherein the gripper apparatus can be offset with respect to the discrete articles by way of the curtains.

6. Gripper apparatus according to one of the preceding claims, wherein the curtain or curtains are adjustable electrically or pneumatically.

7. Gripper apparatus according to one of the preceding claims, wherein the curtains bear against the discrete articles under spring force.

8. Gripper apparatus according to one of the preceding claimsr wherein it is suspended on a resilient apparatus and can be 11 lowered onto and placed on the discrete articles by means of this apparatus.

9. Gripper apparatus according to one of the preceding claims, wherein the position of the curtains with respect to a fixed point on the gripper apparatus can be determined by means of path and/or angle measurement elements.

10. Gripper apparatus according to one of the preceding claims, wherein the curtains are of flexible or rigid, in particular plate-type material.

11. Gripper apparatus according to one of the preceding claims, wherein pallet grippers which can be pivoted in are provided on the longitudinal sides.

12. Gripper apparatus according to one of the preceding claims, wherein an apparatus altering the pressure of attraction by suction, e.g. a by- pass, a choke. or an infiltrated air flap, a pump pressure reduction means or the like, is provided, in particular on the gripper or on the vacuum blower.

13. Gripper apparatus according to one of the preceding claims, wherein an apparatus for bearing the layers of discrete articles attracted by suction, in particular a perforated metal sheet, is provided, the holes of the perforated metal sheet being dimensioned so as to maintain the applied reduced pressure.

14. Gripper apparatus according to one of the preceding claims, wherein a control circuit for re-adjusting the pressure in the gripper is provided which controls in particular an infiltrated air flap, in particular by way of a proportional valve.

15. Gripper apparatus according to one of the preceding claims, wherein an apparatus forming a flow resistance is provided in the suction box, in particular behind a perforated metal sheet lying on the layer of discrete articles.

1 12

16. Gripper apparatus according to Claim 15, wherein tho? apparatus forming a flow resistance is formed by an open-cell, in particular compressible, foam material which in particular comprises a plurality of individual bodies lying next to one another.

17. Gripper apparatus according to Claim 15, wherein the apparatus forming a flow resistance is formed by a plurality of flow valves arranged in the manner of a grid, it being possible to actuate each flow valve individually.

18. Gripper apparatus according to Claim 17, wherein the flow valve has a tappet which can be actuated by the object to be raised of a layer of discrete articles, it being possible to offset the tappet by means of the object from a rest position closing the valve to a working position opening the valve.

19. Use of the gripper apparatus according to one of the preceding claims in refrigerated sheds for handling frozen articles.