ATTACHMENT OF A TRAY GRIPPER OF A TRAY SEALING MACHINE

Abstract

A tray gripper may be attached to a gripper arm of a tray sealing machine. For this purpose, the tray gripper is moved to a pre-assembly position by hooking the tray gripper onto the gripper arm. In addition, an eccentric is operated for exerting a clamping force upon the tray gripper that is disposed in the pre-assembly position, so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to German patent application number DE 10 2019 206 384.5, filed May 3, 2019, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the detachable attachment of a tray gripper to a packaging machine that is formed as a tray sealing machine.

BACKGROUND

An exemplary tray sealing machine is known from EP 3 138 778 A1. The tray sealing machine comprises arranged consecutively in the direction of production a feed belt for packaging trays to be sealed, a sealing device for sealing the packaging trays, and a discharge belt for the sealed packaging trays. A gripper system is provided which relocates the trays to be packaged from the feed belt into the sealing device and relocates the sealed trays from the sealing device onto the discharge belt. The gripper system comprises two gripper arms that are movable in and against the direction of production and which, regarding the direction of production, are arranged on opposite sides of the trays. Two tray grippers are detachably attached on each of the gripper arms. Two respective tray grippers each provided on opposite sides of the trays interact for relocating, trays from the feed belt into the sealing device, while the other two oppositely disposed tray grippers interact for relocating sealed trays from the sealing device onto the discharge belt. The tray grippers each comprise a first and a second holding fixture, by way of which they are attachable and detachable in a keyless manner on and from a coupling device of the respective gripper arm. The holding fixtures each comprise two respective mounting bolts which are mounted at a fixed distance to each other on an adjustment plate attached in an adjustable manner to the tray gripper. The mounting bolts are received in U-shaped openings of the coupling device. For this purpose, the mounting bolts have a reduced diameter at their central portion which is provided in a precise fit for the U-shaped opening. After inserting the mounting bolts into the openings, a spring plate of the coupling device ensures a reliable connection of the tray gripper to the coupling device in that the spring plate in part encloses a mounting bolt. For detaching, the spring plate must be manually pushed away from the mounting bolt so that the tray gripper may be removed.

Gripper systems are also known from practice in which only one tray gripper is provided on each gripper arm and is responsible for relocating the trays into the sealing device as well as relocating the sealed trays out of the sealing device.

For a high throughput of the tray sealing machine, it is desirable to relocate the trays as quickly as possible. However, this results in very high forces acting upon the tray grippers when accelerating or decelerating. This is particularly critical with tray grippers which are shaped to be particularly long in order to be able to simultaneously relocate as many trays as possible. During operation, oscillations and vibrations of the tray grippers may arise, which may have a negative effect on the positioning accuracy and may cause faults.

SUMMARY

It is an object of the disclosure to provide a way of detachably attaching a tray gripper to a gripper arm of a tray sealing machine which allows for simple and quick exchange of the tray gripper and/or allows for particularly stable attachment.

According to the disclosure, a method for detachably attaching a tray gripper to a gripper arm of a tray sealing machine is provided. The tray gripper is moved to a pre-assembly position by hooking the tray gripper onto the gripper arm. By operating an eccentric, a clamping force is exerted on the tray gripper that is disposed in the pre assembly position, so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

By using the eccentric, a high tensioning force may be obtained for stable and reliable attachment of the tray gripper. Since the attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm, the tray gripper may be tensioned to the gripper arm in a well-defined position.

The eccentric is preferably adjusted between a receiving position and a tensioning position. In the receiving position, the tray gripper may be moved to the pre-assembly position. In the tensioning position, the attachment structure of the tray gripper is tensioned against the abutment. structure of the gripper arm. If the tray gripper is to be removed, the eccentric may be adjusted from the tensioning position to the receiving position, so that the attachment structure of the tray gripper is released.

The eccentric is preferably operated by operating a lever connected to an axis of the eccentric. Due to the lever effect, it is then easy to apply sufficiently high tensioning force. In the receiving position of the eccentric, the lever preferably projects away from the gripper arm and in the tensioning position of the eccentric bears against the gripper arm. This ensures that the lever does not represent an obstacle during operation of the tray sealing machine when the tray gripper is mounted. In addition, bearing against the gripper arm in the tensioning position may give a feedback about a correct tensioning of the tray gripper.

According to an easy-to-implement embodiment, the force upon the tray gripper by the eccentric is exerted directly by way of contact between the eccentric and the tray gripper. When tensioning the tray gripper against the abutment structure of the gripper arm, the eccentric may come into contact with the tray gripper and tension it directly against the abutment structure of the gripper arm.

Alternatively, the force by the eccentric upon the tray gripper may also be exerted indirectly via an intermediate element. This allows for the eccentric to be positioned and dimensioned more freely. In addition, the intermediate element may be designed and shaped for particularly good force transmission and/or a particularly good engagement with the tray gripper.

The intermediate element may be mounted, for example, to be slidable on a body of the gripper arm. With the mounting, a slide path of the intermediate element for tensioning the gripper arm may be specified.

The intermediate element preferably comprises a receiving structure, which receives the attachment structure of the tray gripper. In such an embodiment, particularly good force transmission between the intermediate element and the tray gripper is given. The receiving structure preferably receives the attachment structure of the tray gripper already in the pre-assembly position.

In order to obtain an increased tensioning force, at least one region of the intermediate element may be elastically deformed by the eccentric. In particular, the region of the intermediate element may be elastically deformed when the eccentric is operated for exerting the tensioning force, in particular when adjusting the eccentric to the tensioning position.

For a particularly vibration-resistant and defined attachment of the tray gripper, a line contact between the attachment structure and the gripper arm may be present when the attachment structure of the tray gripper is tensioned against the abutment structure of the gripper arm. Preferably, there are even several line contacts present between the attachment structure and the gripper arm, in particular at least two, at least three or at least four line contacts.

The eccentric may provide a tensioning force in the order of magnitude of, for example, 20 kN. In particular, the tensioning force may be at least 10 kN, at least 15 kN or at least 20 kN.

The disclosure also relates to a tray sealing machine. The tray sealing machine is suitable, adapted, and configured to perform the method according to the disclosure. Features described with regard to the method may be transferred to the tray sealing machine and vice versa.

A tray sealing machine according to the disclosure comprises a sealing device for sealing trays and a gripper system for introducing the trays into the sealing device. The gripper system is preferably also configured to remove the sealed trays from the sealing device. The gripper system comprises a gripper arm and a tray gripper for gripping the trays that is detachably attachable to the gripper arm. Preferably, two gripper arms are provided, on each of which at least one tray gripper for gripping the trays may be attached in a detachable manner.

The gripper arm comprises an eccentric which is operable to be adjusted between a receiving position and a tensioning position. In the receiving position of the eccentric, the tray gripper may be made to assume a pre-assembly position by hooking the tray gripper onto the gripper arm. The eccentric is configured to be adjusted to the tensioning position when the tray gripper is in the pre-assembly position. The eccentric thereby exerts a force upon the tray gripper, so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

The gripper arm preferably also comprises a lever for operating the eccentric connected to an axis of the eccentric. In the receiving position of the eccentric, the lever preferably projects away from the gripper arm and in the tensioning position of the eccentric, the lever bears against the gripper arm.

According to an embodiment, an intermediate clement is mounted to be slidable on a body of the gripper arm. The force upon the tray gripper when adjusting the eccentric to the tensioning position is exerted indirectly via the intermediate element.

The intermediate element may comprise a receiving structure which receives the attachment structure of the tray gripper. The receiving structure is preferably formed to be hook-shaped. This allows for particularly simple but also reliable reception of the attachment structure of the tray gripper and enables improved force transfer to the tray gripper.

In order to apply increased tensioning force for attaching the tray gripper, the intermediate element may comprise a region that is elastically deformable by the eccentric when the eccentric is adjusted to the tensioning position.

The abutment structure of the gripper arm may form a support for a line contact with the attachment structure of the tray gripper. The abutment structure of the gripper arm preferably even forms a support for more than one line contact with the attachment structure, for example, for at least two, at least three or at least four line contacts with the attachment structure.

The gripper arm preferably extends from the tray gripper upwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments according to the disclosure are explained in more detail with reference to the attached figures, where:

FIG. 1 shows a schematic perspective view of a tray sealing machine according to an embodiment;

FIG. 2 shows a schematic perspective view of the gripper system of the tray sealing machine according to the embodiment;

FIG. 3 shows a view of the gripper system from FIG. 2 in the viewing direction along the direction of production upon insertion of a tray gripper into the pre-assembly position according to an embodiment;

FIG. 4 shows a detailed view of section A from FIG. 3;

FIG. 5 shows the detailed view from FIG. 4 after the tray gripper has been inserted into the pre-assembly position;

FIG. 6 shows the detailed view from FIGS. 4 and 5 after the tray gripper has been tensioned onto the gripper arm;

FIG. 7 shows a schematic detailed view for illustrating the abutment structure of the gripper arm according to an embodiment;

FIG. 8 shows a schematic view of the attachment of the tray gripper to the gripper arm according to an alternative embodiment; and

FIG. 9 shows a schematic representation of the attachment of the tray gripper to the gripper arm according to a further alternative embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a tray sealing machine 1 according to an embodiment. Arranged consecutively along a direction of production P, tray sealing machine 1 comprises a feed device 3 embodied as a feed belt for packaging trays to be sealed, a sealing device 5 for sealing the packaging trays, and a discharge device 7 embodied as a discharge belt for sealed packaging trays. Sealing device 5 seals the packaging trays by sealing a top film on, which is withdrawn from a stock roll that is received on a film holder 9. For sealing the top film on, sealing device 5 comprises a sealing tool upper part 11 and a sealing tool lower part 13 which are movable along a vertical direction relative toward each other to seal between themselves the top film to the packaging trays. The sealing may be done, for example, subject to heat and/or pressure. A cutting device may also be integrated into sealing device 5 and cut the top film during or after the sealing process, thereby separating the packagings from the composite of the top film. A residual film lattice of the top film may be wound onto a residual film winding device 15.

Tray sealing machine 1 comprises a gripper system 17 for relocating packaging trays to be sealed from feed device 3 into sealing device 5. Gripper system 17 is shown individually in FIG. 2. Gripper system 17 comprises a carriage 19 which is mounted on two guide rods 21 extending parallel to the direction of production P to be slideable in and against the direction of production P by way of a drive 23. On both lateral sides with respect to the direction of production P, a gripper arm 25 is provided on carriage 19. The gripper arms 25 extend down from carriage 19. Respective tray grippers 27 are detachably attachable to gripper arms 25. In FIG. 2, a tray gripper 27 is attached to one of gripper arms 25, while other gripper arm 25 is shown without tray gripper 27 to illustrate the attachment mechanism. Gripper arms 27 extend substantially parallel to the direction of production P. By pivoting the gripper arms 25 relative to each other about axes running parallel to the direction of production P, the tray grippers 27 may be moved toward each other and in this manner may receive trays disposed between them. Carriage 19 may subsequently move along the direction of production P, whereupon the trays may be placed at a different position by pivoting gripper arms 25 apart from each other.

In the embodiment shown, exactly one tray gripper 27 is attachable to each gripper arm 25. Preferably, gripper system 17 may in one process step relocate packaging trays to be sealed from feed device 3 into sealing device 5 and sealed packaging trays from sealing device 5 to discharge device 7. For this purpose, tray grippers 27 are formed to be sufficiently long such that packaging trays present on feed device 3 and already sealed packaging trays in sealing device 5 may simultaneously be gripped. After gripping them, carriage 19 moves along the direction of production P and then places the packaging trays to be sealed, that were received from feed device 3, into sealing device 5 and the sealed packaging trays, that were received in sealing device 5, onto discharge device 7. However, it would also be conceivable to provide two (or more than two) separate tray grippers 27 on each gripper arm 25, of which, for example, one is responsible for feeding the packaging trays to be sealed into sealing device 5 and one for removing the sealed packaging trays from sealing device 5.

Tray grippers 27 should be detachably attached to the gripper arms 25 to allow for an exchange of tray grippers 27, for example for retooling tray sealing machine 1 to a different tray format. The attachment of tray grippers 27 on gripper arms 25 may be formed similarly for both gripper arms 25 and is explained in the following first for an embodiment shown in FIGS. 2 to 7. FIG. 3 shows gripper system 17 in the viewing direction along the direction of production P. Gripper system 17 comprises a lever 29 at each of gripper arms 25 which is movable between a receiving position and a tensioning position for the tensioning attachment of tray gripper 27. In FIG. 3, lever 29 of left gripper arm 25 is in the receiving position, whereas lever 29 of right gripper arm 25 is in the tensioning position. In the receiving position, lever 29 protrudes out from gripper arm 25. In the tensioning position, lever 29 bears against gripper arm 25.

FIG. 4 shows a detailed view of detail A from FIG. 3. In the embodiment shown, an intermediate element 33 is mounted to be movable on a body 31 of gripper arm 25. In particular, intermediate element 33 is mounted on body 31 for a motion in a horizontal plane along a direction V disposed perpendicular to the direction of production P. Intermediate element 33 in the illustrated embodiment has two hook-shaped receiving structures 35 and an end plate 39 connected to receiving structures 35. If lever 29 is in the receiving position, as shown in FIG. 4, a reset element 41 of lever 29 engages with end plate 39 of intermediate element 33 and in FIG. 4 slides it in the sliding direction V to the right, so that attachment structures 43 of tray gripper 27 formed as rods extending parallel to the direction of production P may be inserted into hook-shaped receiving structures 35 of intermediate element 33. FIG. 5 shows the arrangement in a pre-assembly position after insertion of attachment structures 43 of tray gripper 27 into receiving structures 35 of intermediate element 33 mounted to be slidable on body 31 of gripper arm 25. In the pre-assembly position, tray gripper 27 is already held independently on gripper arm 25 and need no longer be held by an operator during the further steps of tensioning tray gripper 27 onto gripper arm 25.

Lever 29 is connected to an axis 45 that extends parallel to the direction of production P and is mounted to be rotatable on gripper arm 25. Provided on axis 45 is also an eccentric 47 which is rotated when axis 45 is rotated by rotating lever 29. In the receiving position of lever 29 (FIGS. 4 and 5), eccentric 47 is also in a receiving position. In its receiving position, eccentric 47 exerts no force upon intermediate element 33.

In order to firmly lock gripper arm 25 hooked onto tray gripper 27 in the pre-assembly position, lever 29 is pivoted from the receiving position shown in FIG. 5 to a tensioning position shown in FIG. 6. While lever 29 in the receiving position projects away from gripper arm 25, in particular vertically, lever 29 in the tensioning position bears against gripper arm 25. When lever 29 is rotated to the tensioning position (in FIG. 5 clockwise), eccentric 47 is also rotated. With this rotation, eccentric 47 engages with end plate 39 of intermediate element 33, whereby intermediate element 33 in the representation of FIGS. 4 to 6 is moved in the sliding direction V to the left during this motion, tray gripper 27 is entrained. Attachment structures 43 of tray gripper 27 are moved toward body 31 of gripper arm 25 and finally tensioned against an abutment structure 49 of gripper arm 25. In FIG. 7, an abutment structure 49 for attachment structure 43 of tray gripper 27 is shown by way of example. Abutment structure 49 comprises a substantially V-shaped notch in body 31 of gripper arm 25 which extends parallel to the direction of production P. When attachment structure 43 of tray gripper 27 is tensioned against abutment structure 49 of gripper arm 25 due to the tensioning force exerted by eccentric 47 via intermediate element 33 upon attachment structure 43 of tray gripper 27, rod-shaped attachment structure 43 comes into contact with the notch along two lines. Due to these line contacts parallel to the direction of production P, tray gripper 27 may be attached in a particularly stable manner. In particular, tray gripper 27 is well stabilized against vibrations. Since two attachment structures 43 are present in the embodiment shown for every tray gripper 27 and are each tensioned against an abutment structure 49 of gripper arm 25, there are a total of four line contacts given between tray gripper 27 and gripper arm 25. Although the variant shown with two superimposed attachment structures 43 of tray gripper 27 provides a particularly stable attachment, it would be conceivable in principle to provide only one attachment structure 43 for every tray gripper 27. Of course, more than two attachment structures 43 may also be provided. As shown in FIG. 7, abutment elements 51 in the form of rods made of steel may be provided in the notch in body 31 of gripper arm 25 and provide the contact surfaces to attachment structure 43 of tray gripper 27.

In order to be able to tension attachment structure 43 with a particularly high tensioning force against abutment structure 49 of gripper arm 25, eccentric 47 in the tensioning position may elastically deform rear plate 39 of the intermediate element.

If tray gripper 27 is to be removed again, lever 29 is pivoted from the tensioning position back to the receiving position. Eccentric 47 then no longer exerts tensioning, force and tray gripper 27 may again be removed. In the embodiment shown, a reset element 41 is provided on lever 29 which engages with end plate 39 of intermediate element 33 when lever 29 is moved to the receiving position and again slides intermediate element 33 such that tray gripper 27 may be easily removed (sliding in sliding direction V to the right in FIGS. 4 to 6). However, it would also be conceivable to manually slide intermediate element 33 by pulling on tray gripper 27 when the tensioning force by eccentric 47 is no longer present.

FIG. 8 shows an alternative embodiment of the tensioning connection between gripper arm 25 and tray gripper 27. In this embodiment, attachment structures 43 of tray gripper 27 are not formed as rods extending parallel to the direction of production P, but as hook structures. Lever 29 is again provided pivotable on gripper arm 25. In addition, two rods 55 are fixedly attached to gripper arm 25. Tray gripper 27 may be hooked by way of hook-shaped attachment structures 43 onto rods 55 of gripper arm 25 and thereby made to assume a pre-assembly position. Subsequently, lever 29 may be adjusted by pivoting clockwise from the receiving position shown in FIG. 8 to a tensioning position. An eccentric 47 again rotates together with lever 29 and, when rotating lever 29 to the tensioning position, is pressed against an engagement region 57 of tray gripper 27 and thereby moves tray gripper 27 away from gripper arm 25. Hook-shaped attachment structures 43 of tray gripper 27 are thus pressed against rods 55 of gripper arm 25, which in this case form the abutment structure 49 of gripper arm 25. For releasing the attachment, lever 29 may be rotated from the tensioning position again counterclockwise to the release position, whereupon tray gripper 27 may be removed. In the embodiment according to FIG. 8, eccentric 47 engages directly with tray gripper 27 and no intermediate element 33 is provided.

FIG. 9 shows a further embodiment of the connection between tray gripper 27 and gripper am 25 in which eccentric 47 engages without intermediate element 33 directly with tray gripper 27. Similar to the embodiment of FIGS. 2 to 7, attachment structure 43 of tray gripper 27 is in this embodiment formed by a rod extending parallel to the direction of production P. A hook 58 is provided on gripper arm 25. In addition, a lever 29 that may be rotated between a receiving position and a tensioning position is again provided with an eccentric 47 on gripper arm 25. In the receiving position of lever 29 and eccentric 47 shown in FIG. 9, tray gripper 27 may be hooked in a pre-assembly position onto gripper arm 25 by hooking attachment structure 43 into hook 58 of gripper arm 25. From this pie-assembly position, lever 29 may be rotated clockwise. Eccentric 47 is thereby rotated to a tensioning position, where it engages with attachment structure 43 of tray gripper 27 and pushes the latter in the direction away from gripper arm 25. Attachment structure 43 of tray gripper 27 is thereby tensioned against an abutment structure 49 formed by hook 58 whereby gripper arm 27 is locked. If gripper arm 27 is to be removed again, lever 29 may again be rotated counterclockwise to the receiving position, whereby the tensioning force by eccentric 43 is cancelled.

Claims

1. A method for detachably attaching a tray gripper to a gripper arm of a tray sealing machine, comprising: moving the tray gripper into a pre-assembly position by hooking the tray gripper onto the gripper arm; andoperating an eccentric for exerting a clamping force upon the tray gripper that is disposed in the pre-assembly position, so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

2. The method according to claim 1, wherein operating the eccentric causes adjustment of the eccentric between a receiving position, in which the tray gripper is configured to be moved to the pre-assembly position, and a tensioning position, in which the attachment structure of the tray gripper is tensioned against the abutment structure of the gripper arm.

3. The method according to claim 2, wherein operating eccentric comprises operating a lever that is connected to an axis of the eccentric, wherein the lever in the receiving position of the eccentric projects away from the gripper arm and in the tensioning position of the eccentric bears against the gripper arm.

4. The method according to claim 1, wherein the force upon the tray gripper by the eccentric is exerted indirectly via an intermediate element.

5. The method according to claim 4, wherein the intermediate element is mounted to be slidable on a body of the gripper arm.

6. The method according to claim 4, wherein the intermediate element comprises a receiving structure which receives the attachment structure of the tray gripper.

7. The method according to claim 4, wherein at least one region of the intermediate element is elastically deformed by the eccentric.

8. The method according to claim 1, wherein the force upon the tray gripper by the eccentric is exerted directly by contact between the eccentric and the tray gripper.

9. The method according to claim 1, wherein a line contact between the attachment structure and the gripper arm is present when the attachment structure of the tray gripper is tensioned against the abutment structure of the gripper arm.

10. A tray sealing machine with a sealing device for sealing trays and a gripper system for introducing the trays into the sealing device, the gripper system comprising; a gripper arm; anda tray gripper detachably attachable to the gripper arm for gripping the trays;wherein the gripper arm comprises an eccentric which is operable to be adjusted between a receiving position and a tensioning position;in the receiving position of the eccentric, the tray gripper is configured to be brought into a pre-assembly position by hooking the tray gripper onto the gripper arm; andthe eccentric is configured to be adjusted to the tensioning position when the tray gripper is in the pre-assembly position and to thereby exert a force upon the tray gripper so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

11. The tray sealing machine according to claim 10, wherein the gripper arm further comprises a lever that is connected to an axis of the eccentric for operating the eccentric, wherein the lever in the receiving position of the eccentric projects away from the gripper arm and in the tensioning position of the eccentric bears against the gripper arm.

12. The tray sealing machine according to claim 10, further comprising an intermediate element mounted to be slidable on a body of the gripper arm, wherein the force upon the tray gripper when adjusting the eccentric to the tensioning position is exerted indirectly via the intermediate element.

13. The tray sealing machine according to claim 12, wherein the intermediate element comprises a receiving structure that is configured to receive the attachment structure of the tray gripper.

14. The tray ceiling machine according to claim 13, wherein the receiving structure is hook-shaped.

15. The tray sealing machine according to claim 12, wherein the intermediate element comprises a region that is elastically deformable by the eccentric when the eccentric is adjusted to the tensioning position.

16. The tray sealing machine according to claim 10, wherein the abutment structure of the gripper arm forms a support for a line contact with the attachment structure of the tray gripper.

17. A method for detachably attaching a tray gripper to a gripper arm of a tray sealing machine, the method comprising: moving the tray gripper into a pre-assembly position by hooking the tray gripper onto the gripper arm; andoperating an eccentric for exerting a clamping force upon the tray gripper that is disposed in the pre-assembly position, so that an attachment structure of the tray gripper is urged against an abutment structure of the gripper arm.