The invention concerns a gripper device for opening or closing foldable side walls of a folding crate or a cardboard box or similar, comprising a first gripper for gripping a first side wall of the side walls, a second gripper for gripping a second side wall of the side walls, a first actuator and a second actuator for generating control movements for controlling the first gripper and the second gripper, and transfer means for transferring the control movements of the actuators into displacement movements of the first gripper and second gripper for opening or closing the foldable side walls.

The text below discusses a gripper device for opening a folding crate. A gripper device according to this invention may however, mutatis mutandis, also be used for other purposes such as for example opening or closing foldable side walls of a cardboard box.

Said side walls of such a folding crate are moved by means of such a gripper device between an open state for folding open (opening) the folding crate and a closed state for folding closed (closing) the folding crate.

The invention also concerns a folding crate opener for opening or closing a folding crate, comprising a displacement device for displacing the folding crate in a transport direction, a first gripper device for opening or closing foldable side walls of the folding crate which extend in the transport direction, and a second gripper device for opening or closing foldable side walls of the folding crate which extend transversely to the transport direction.

An example of such a folding crate opener with such gripper devices is described and depicted in EP 2 181 841 Al. The present invention, more specifically but without restriction, relates to said second gripper device of such a folding crate opener. This second gripper device from EP 2 181 841 Al comprises a heavy structure in which the grippers are provided. This heavy structure must be moved in order to achieve the displacement movement of the grippers. High inertia is associated with the movement of such a heavy structure, whereby very high mass forces must be absorbed. Thus there is a limit to the speed of and hence the capacity for opening or closing folding crates.

The object of this invention is to provide an alternative such gripper device which can be designed lighter than said second gripper device, so that the capacity of such a gripper device can be increased or so that lighter actuators may be used for control in such a gripper device.

This object is achieved by the provision of a said gripper device in which the transfer means comprise: a first guide element which is displaceable in a first linear displacement direction by means of the control movement of the first actuator; a second guide element which, viewed in the first linear displacement direction, is arranged offset relative to the first guide element and is displaceable in this first linear displacement direction by means of the control movement of the second actuator; a first transmission arm which on the one hand is connected to the first guide element so as to be pivotable about a first pivot axis and on the other hand is connected to the first gripper; a second transmission arm which on the one hand is connected to the second guide element so as to be pivotable about a second pivot axis and on the other hand is connected to the first gripper; a third transmission arm which on the one hand is connected to the first guide element so as to be pivotable about a third pivot axis and on the other hand is connected to the second gripper; and a fourth transmission arm which on the one hand is connected to the second guide element so as to be pivotable about a fourth pivot axis and on the other hand is connected to the second gripper; wherein the first transmission arm or the second transmission arm is connected to the first gripper pivotable about a fifth pivot axis and respectively the second transmission arm or the first transmission arm is fixedly connected to the first gripper, and wherein the third transmission arm or the fourth transmission arm is connected to the second gripper pivotable about a sixth pivot axis and respectively the fourth transmission arm or the third transmission arm is fixedly connected to the second gripper. By varying the spacing of the guide elements relative to one another, and the distance relative to the folding crate to be opened or closed, each gripper can be displaced in a plane. In this way, the grippers can be controlled to perform a desired displacement movement in order to open or close such a folding crate. Since only the transfer means need be moved for this, the parts to be moved may be much lighter than in the prior art.

As in the prior art, the folding crate may be placed with its base horizontal, wherein using the gripper device, the grippers are moved from above down to the folding crate or up away from this so as to open or close the folding crate. It is however also possible, using a gripper device according to this invention, for example to place such a base vertically and move the grippers substantially horizontally up to and away from the folding crate. Furthermore, using such a gripper device, it is also possible to move these from below up to a folding crate of which the base is for example placed at the top.

In a gripper device according to this invention, the fifth pivot axis is preferably provided for connecting the second transmission arm to the first gripper, and the sixth pivot axis is preferably provided for connecting the fourth transmission arm to the second gripper. The hook mechanism may thus be implemented more simply.

The displacement movements of the first gripper and second gripper of a gripper device according to this invention take place in one or more parallel displacement planes. The first linear displacement direction is parallel to said one or more displacement planes. Even more preferably, both grippers are displaceable in the same displacement plane.

In a preferred embodiment, the transfer means comprise: first guide means for guiding the displacement movement of the first guide element in the first linear displacement direction; and second guide means for guiding the displacement movement of the second guide element in the first linear displacement direction. The first guide means and the second guide means more specifically comprise a same guide rail which extends substantially in the first linear displacement direction.

A gripper device according to this invention furthermore comprises one or more limiters for limiting the displacement movements of the guide elements. These limiters limit the displacement movements, preferably in both directions, at an outermost position.

Furthermore, the displacement movement of the second guide element is preferably limited as a function of the displacement movement of the first guide element, preferably such that the mutual distance between the first guide element and second guide element is limited between a minimum and a maximum.

The second guide element is more specifically arranged between the first guide element and the first gripper, and between the first guide element and the second gripper.

Here the second pivot axis and the fourth pivot axis lie at approximately the same distance relative to the respective grippers. The first pivot axis and the third pivot axis also lie at approximately the same distance relative to the respective grippers.

The first transmission arm and the third transmission arm have approximately the same length and are designed longer than the second transmission arm and the fourth transmission arm, which also have approximately the same length.

The second pivot axis and the fourth pivot axis are preferably arranged as close as possible to one another. The second pivot axis and said fourth pivot axis may in principle also coincide and be configured as a common pivot axis. Preferably however, a distance is provided between the two.

The first pivot axis and the third pivot axis are preferably different pivot axes which preferably are arranged further apart from one another than the second pivot axis and the fourth pivot axis. The distance between the first pivot axis and the third pivot axis is then greater than the distance between the second pivot axis and the fourth pivot axis. In this way, the associated transmission arms can be brought close to one another in order to be able to also grip with the grippers side walls which, in closed state, almost touch one another. The grippers are preferably connected to the respective transmission arms by means of a fixing body, so that each gripper can easily be replaced by removing/installing this on the fixing body. They can for example easily be replaced on a fault or change of gripper type. Thus for example, as in the prior art, different grippers may be provided for different sizes of folding crates.

Preferably, the grippers are however multifunctional so that they can be used for different sizes of folding crates. More specifically, for this the first gripper may comprise a first hook element which points towards the second gripper, and a second hook element which is provided below the first hook element and points away from the second gripper. Similarly, the second gripper may comprise a first hook element which points towards the first gripper, and a second hook element which is provided below the first hook element and points away from the first gripper. By means of the second hook element, the top edges of said side walls can be gripped in order to open or close the side walls, while by means of the first hook element, the folding crate can be opened or closed by bringing the grippers into handles in the side walls of these folding crates.

The object of this invention is furthermore achieved by the provision of a folding crate opener for opening or closing a folding crate, comprising a displacement device for displacing the folding crate in a transport direction, a first gripper device for opening or closing foldable side walls of the folding crate which extend in the transport direction, and a second gripper device for opening or closing foldable side walls of the folding crate which extend transversely to the transport direction, wherein the second gripper device is a gripper device according to this invention as described above.

This invention will now be explained in more detail below with reference to the following detailed description of a preferred folding crate opener with only preferred gripper devices according to this invention. The object of this description is solely to give clarifying examples and indicate further advantages and features of this invention, and may thus in no sense be interpreted as a restriction of the area of application of the invention or of the patent rights claimed in the claims.

In this detailed description, reference is made by means of reference signs to the appended drawings in which: figure 1 shows in perspective a part of a device for opening folding crates which comprises two folding crate openers according to this invention; figure 2 shows a folding crate opener from figure 1 separately in perspective; figure 3 shows a gripper device of a folding crate opener from the device from figure 1, separately in perspective and viewed from the rear; figure 4 shows the gripper device from figure 3 in perspective, viewed from the front; figure 5 - 11 show in a rear view, in various stages, how a folding crate can be opened by means of a gripper device in figure 3 using first hook elements of the grippers; figures 12 - 20 show in perspective from the rear, in various stages, how a folding crate can be opened by means of a gripper device from figure 3 using the second hook elements of the grippers.

The device (1) shown in figure 1 is provided for opening folding crates (8). These folding crates (8) are delivered in a known fashion via a conveyor belt (2) in a transport direction (X), wherein they are arranged with their base flat on said conveyor belt (2) and the side walls (9, 10) are folded down over this base. By means of a further transport device, said folding crates (8) are then conducted through a first folding crate opener (3) and a second folding crate opener (4). Depending on the dimensions of the folding crates (8), these are opened either in the first folding crate opener (3) or in the second folding crate opener (4). Then these folding crates (8) are conducted in a known fashion through a test device (5) for checking.

The folding crate openers (3, 4) each comprise a first gripper device (6, 6') for folding open, in the known fashion, the side walls (9) of the folding crates (8) which are attached to the base by pivot axes which extend in the transport direction (X).

In addition, the folding crate openers (3, 4) each comprise a second gripper device (7, 7') according to this invention for opening the side walls (10) of the folding crates (8) which are attached to the base by pivot axes which extend in a direction (Y) transversely to the transport direction (X). The gripper devices (7, 7') according to the invention comprise a first gripper (11) and a second gripper (12) which grip the side walls (10) and are moved up in a circular movement to open the side walls (10).

To control this movement, two guide elements (15, 16) are arranged sliding by means of guide feet (28) on a common guide rail (27) which extends in a height direction (Z). These guide elements (15, 16) are both actuated independently of one another by two servo motors (13, 14). The rotating movement of each servo motor (13, 14) is converted by means of a drive pulley (33) to a toothed belt (35) which returns via a reversing pulley (34). Each guide element (15, 16) is fixed relative to a respective toothed belt (35) by a clamping bracket (36). In figure 4, the clamping bracket (36) of the first guide element (15) is attached to said guide element (15). The clamping bracket (36) of the second guide element (16) is shown in figure 4 at a distance below said guide element (16), but in mounted state is also attached to said second guide element (16). By means of the toothed belt (35) and clamping bracket (36), the rotating movement of the servo motor (13, 14) is converted into a corresponding vertical movement of the respective guide element (15, 16) on the guide rail (27).

The first guide element (15) is arranged furthest away from the grippers (11, 12) while the second guide element (16) is provided closer to the grippers (11, 12) at a distance from the first guide element (16).

The motors (13, 14) are provided on the front of a frame (37), wherein the drive pulleys (33) are arranged on the rear of said frame (37). The shafts of the motors (13, 14) are arranged rotatably through the frame (37) The reversing wheels (34) and the guide rail (27) are also mounted on the rear of said frame (37).

The two guide elements (15, 16) extend from the rear of the frame (37) with legs (39) through vertical slots (38) in the frame (37) in order to also protrude on the front of the frame (37).

On the front of the frame (37), a first transmission arm (17) is connected on one side to the first guide element (15) so as to be pivotable about a first pivot axis (21), and on the other side is fixedly connected to a fixing body (43) on which the first gripper (11) is attached. A second transmission arm (18) is connected on one side to the second guide element (16) so as to be pivotable about a second pivot axis (22), and on the other side is connected to the fixing body (43) of the first gripper (1 1) so as to be pivotable about a fifth pivot axis (25).

RECTIFIED SHEET (RULE 91) ISA/EP A third transmission arm (19) is connected on one side to the first guide element (15) so as to be pivotable about a third pivot axis (23), and on the other side is fixedly connected to a fixing body (43) on which the second gripper (12) is attached. A fourth transmission arm (20) is connected on one side to the second guide element (16) so as to be pivotable about a fourth pivot axis (24), and on the other side is connected to the fixing body (43) of the second gripper (12) so as to be pivotable about a sixth pivot axis (26).

By moving the two guide elements (15, 16) up and down at the same speed, it is possible to move the grippers (11, 12) up and down. By reducing the distance between the two guide elements (15, 16), it is possible to move the grippers (11, 12) towards one another. By increasing the distance between the two guide elements (15, 16), it is possible to move the grippers (11, 12) away from one another. By the independent movement of the two guide elements (15, 16), it is therefore possible to move to any point in a displacement plane within a specific range. Any manner of movement (straight line, circle) within this displacement plane is thus also possible.

The mutual distance between the two guide elements (15, 16) is limited by a bracket (40). This bracket (40) is connected to the second guide element (16) and is provided with a slot (41). A pin (42) is attached to the first guide element (15) and is arranged slidingly in said slot (41). In this way, the two guide elements (15, 16) are connected together. This achieves two things:

1. The grippers (11, 12) cannot collide with one another when they are moved inward towards one another .

2. The grippers (11, 12) cannot collide with surrounding parts of the folding crate opener (3, 4) when they are moved apart from one another.

The highest position and the lowest position of the two guide elements (15, 16) are limited by rubber dampers (29, 30) so as to prevent the two guide elements (15, 16) from moving too far up or down. The clamping brackets (26) would otherwise be able to collide with the pulleys (33, 34).

In order to ensure that the two transmission arms (17, 18 and 19, 20) of each gripper (11, 12) never lie in the extension of one another, the pivot axes (22, 23) of the top transmission arms (17, 18) on the first guide element (15) are each positioned further from the guide rail (27) than the pivot axes (22, 24) of the bottom transmission arms (18, 20) on the second guide element (16). If the two transmission arms (17, 18 and 19, 20) of each gripper (11, 12) were to lie in the same line, it would not be possible to choose whether the gripper (11, 12) were to move inward or outward at this point. Moving the pivot axes (22, 23) of the top transmission arms (17, 19) on the first guide element (15) outward ensures that the angle of contact of the grippers (11, 12) on the folding crate (8) to be opened or closed is more perpendicular to the base of the folding crate (8). The top transmission arms (17, 19) are fixedly connected to the respective fixing bodies (43) and thus determine the angle of contact. The bottom transmission arms (18, 20) are arranged as close as possible to the line of the guide rail (27) and are attached pivotingly on the respective fixing bodies (43).

Because the transmission arms (17, 18, 19, 20) are connected to the respective grippers (11, 12) by means of fixing bodies (43), these grippers (11, 12) are easy to replace.

In most folding crates (8), a known gripper (11, 12) is sufficient to open the side walls (10). This takes place as illustrated in figures 5 - 11. If the two side walls (10) are however so long that they lie against one another, a problem arises. The grippers (11, 12) can then no longer be arranged between these side walls (10). Therefore the adapted grippers (11, 12) shown in the figures are provided. The first gripper (11) here comprises a first hook element (31) which points towards the second gripper (12), and a second hook element (32) which is arranged below the first hook element (31) and points away from second gripper (12). Similarly, the second gripper (12) comprises a first hook element (31) which points towards the first gripper (11) and a second hook element (32) which is arranged below the first hook element (31) and points away from the first gripper (11). These adapted grippers (11, 12) can thus engage, by means of the second hook element (32), in the handles (44) in the side walls (10) of the folding crates (8), instead of on the top edge of the side walls (10) as illustrated in figures 12- 16. When the side wall (10) is almost upright, as in figure 16, however, a problem arises: the second hook element (32) can no longer move out of the handle (44). Therefore the extra upright first hook element (31) is provided. By moving the grippers (11, 12) slightly upward as shown in figures 17 - 18, the second hook element (32) is cleared and pushes the first hook element (31) against the folding crate (8). When the folding crate (8) is opened, the grippers (11, 12) can be moved down slightly as shown in figures 19 - 20 in order to move out of the handle (44). Instead of the servo motors (13, 14) and toothed belts (35) shown, other actuators may be used to achieve the displacement movement of the guide elements (15, 16). Thus for example a spindle system could also be provided for driving the displacement movement of the guide elements (15, 16).