Device and method for conveying closure lids

Abstract

The invention relates to a device for conveying closure lids, in particular for cans, comprising a stacking device for receiving a stack of closure lids; additionally a transfer device for transferring the respective lowermost closure lid in the stacking device to a device for further processing, wherein the transfer device has at least one receiving area for a closure lid; and a conveyor worm device with at least one conveyor worm and a worm drive, by means of which the at least one conveyor worm can be driven in a drive direction so that the at least one conveyor worm supplies the closure lids individually from the stack to the at least one receiving area of the transfer device. The at least one conveyor worm can be driven and stopped by the worm drive independently of the transfer device, and a controller is provided which is designed to actuate the worm drive after the at least one conveyor worm has been stopped in order to drive the at least one conveyor worm opposite the drive direction before being started up again. The invention also relates to a corresponding method.

Description

[0001] Device and method for conveying closure caps

[0002] The invention relates to a device for conveying closure lids, in particular for cans, comprising a drop stacker for receiving a stack of closure lids, further comprising a transfer device for transferring the respective bottommost closure lids in the drop stacker to a further processing device, wherein the transfer device has at least one receptacle for a closure lid, and comprising a conveyor screw device with at least one conveyor screw and a screw drive, with which the at least one conveyor screw can be driven in a drive direction, so that the at least one conveyor screw feeds the closure lids individually from the drop stacker to the at least one receptacle of the transfer device.

[0003] The invention also relates to a method for conveying closure lids, in particular for cans, in which the closure lids which are respectively lowest in the drop stacker and which contain a stack of closure lids are transferred to a further processing device by means of a transfer device with at least one receptacle for a closure lid, wherein the closure lids are fed individually from the drop stacker to the at least one receptacle of the transfer device by means of at least one conveyor screw driven in a drive direction.

[0004] Can manufacturing devices can be designed in the form of so-called rotary liners. They typically comprise a drop stacker in which a stack of closures is stacked directly on top of one another. A transfer device, which may, for example, have a rotating transfer disc with receptacles on its circumference for each closure, a so-called star wheel, picks up closures from the drop stacker and conveys them to a further processing device, which in turn may, for example, comprise a turntable to which the closures are transferred individually from the receptacles of the transfer disc for further processing, for example, joining to a can body or forming the closures, etc.

[0005] Typically, the lowest closure caps in the drop stacker are fed individually from the drop stacker to the receptacles of the transfer disk by a screw drive with one or more conveyor screws. In the prior art, the drives of the conveyor screw device, the transfer device, and one or more further processing devices are usually mechanically coupled. This ensures particularly reliable synchronization of the various components. On the other hand, in the event of a fault in the drop stacker, for example, triggered by a misaligned closure cap in the drop stacker, or a fault downstream of the drop stacker, this leads to the problem that closure caps continue to be fed from the drop stacker to the transfer device and thus to the further processing device, even though this should no longer be happening due to the fault.

[0006] DE 28 411 45 C2 discloses a device for interrupting the feed during the discharge of can lids from a drop stacker. Interruption elements can be pivoted into the drop stacker above the conveyor screws, interrupting the feed of further lids from the drop stacker. Accordingly, no further lids are fed to the conveyor screws and thus to the downstream components of the device. In this way, for example, in the event of a defect downstream of the drop stacker, an undesired further feed of lids can be prevented. However, adjusting the interruption elements, which are designed as cutting knives, is extremely difficult. This is especially true since access to the drop stacker is generally severely restricted in such devices.Incorrect adjustment of the breakaway elements can result in damage to the closure lids and thus impact production. This applies to both the vertical position of the separating knives and the timing. Height tolerances of the curling of the outer edges of the lids, which affect stack separation, also play a role.

[0007] Another problem lies in the synchronization of the conveyor screws with downstream components, especially a transfer disk. As explained, the mechanical coupling of the drives provided in the state of the art ensures that, once correctly set, the synchronization is reliably maintained. However, the initial synchronization adjustment during mechanical tuning is very complex and must often be performed empirically using a lengthy trial-and-error process.

[0008] Based on the prior art explained above, the object of the invention is therefore to provide a device and a method of the type mentioned at the outset, with which an interruption of the supply of closure caps is made possible in a simple and safe manner and synchronization is facilitated.

[0009] The invention solves the problem by the independent claims 1 and 9. Advantageous embodiments can be found in the dependent claims, the description and the figures.

[0010] For a device of the type mentioned at the outset, the invention solves the problem in that the at least one conveyor screw can be driven and stopped by the screw drive independently of the transfer device, and in that a control device is provided which is designed to control the screw drive after a stop of the at least one conveyor screw to

[0011] ,.. / 4 to drive at least one screw conveyor in the opposite direction to the drive direction before starting up again.

[0012] For a method of the type mentioned at the outset, the invention achieves the object in that the at least one conveyor screw is driven and stopped independently of the transfer device, and in that the at least one conveyor screw is driven counter to the drive direction after a stop and before a renewed start.

[0013] The term "closure lid" is used here in a general sense and can form both the top and bottom lid of a container, for example, a can. It can therefore also be the base of a can, for example. The closure lid can also be part of a package or something similar. In principle, the closure lid can be made of metal, for example, in particular sheet metal. The closure lids can, for example, have a circular shape. However, shapes other than circular are also possible, in particular non-circular closure lids.

[0014] As explained at the beginning, the closure caps in the drop stacker are usually stacked directly on top of each other. The bottommost closure caps of the drop stacker are picked up by the transfer device in at least one of its receptacles and transported by this for further processing in the finishing device. The finishing device can, in principle, be any desired finishing device for the closure caps. For example, it can be a device for forming the closure caps or for connecting the closure caps to other components, such as the base body of a can or packaging. The finishing device can, in particular, be a so-called rotary liner.

[0015] ...15 It could also be, for example, a transfer press for producing tear-off lids or a packaging machine.

[0016] A screw conveyor system with at least one screw conveyor is provided for separating and conveying the bottommost closure caps from the drop stacker to the transfer device. The screw conveyor is driven by a screw drive in one drive direction, in particular rotating in a first direction. The screw conveyor picks up the bottommost closure caps from the drop stacker in its screw thread, thus separating them, and feeds them to the receiving area of ​​the transfer device. A control device is provided for controlling the screw drive.

[0017] According to the invention, it is initially provided that the at least one screw conveyor can be driven and stopped by the screw drive independently of the transfer device. It is also possible for the at least one screw conveyor to be driven and stopped by the screw drive independently of the further processing device or other components of the device for processing the closure caps. While the at least one screw conveyor is stopped, the transfer device and / or the further processing device can therefore continue to run. The possibility of stopping the at least one screw conveyor independently of the transfer device and, if applicable, the further processing device allows the supply of closure caps to be interrupted very quickly, for example in the event of faulty conveying or incorrect alignment of a closure cap or another error downstream of the drop stacker.According to the invention, the screw drive is not coupled to the drives of the transfer device and, if applicable, the further processing device. This makes it easy to interrupt the further supply of closure caps via the at least one conveyor screw to the transfer device.

[0018] ...16 interrupter elements designed as separating knives that can be pivoted into the drop stacker are therefore not necessary, thus avoiding the associated problems discussed above. Furthermore, in the prior art, the separating knives are arranged above the screw(s), and thus it is often unavoidable that, despite the intended interruption, several more lids are still fed in, with corresponding consequences. These problems are also avoided by the invention.

[0019] After the at least one conveyor screw has stopped and the transfer device continues to run, the at least one conveyor screw must be accelerated significantly within a short period of time when it starts up again in order to reliably and synchronously feed the closure caps conveyed by the at least one conveyor screw to the at least one receptacle of the continuing transfer device. In particular with fast-running transfer devices which, for example, convey more than 1,000 closure caps per minute, this is not always reliably possible due to a possibly only short start-up path of the at least one conveyor screw. Therefore, the invention further provides that the at least one conveyor screw is driven by the screw drive against the drive direction, i.e. in particular against the first direction of rotation, after a stop and before starting up again.The at least one screw conveyor is retracted by a specific travel distance after stopping and before starting up again. This maximizes the available travel distance when the at least one screw conveyor is started up again, allowing the at least one screw conveyor to be accelerated sufficiently over this extended travel distance. This ensures reliable synchronization of the at least one screw conveyor with the transfer device, even with a fast-running transfer device, and thus a reliable, synchronized transfer of the closure caps into the at least one receptacle of the transfer device.

[0020] ,.. / 7 direction in a simpler manner and up to automated synchronization is possible. The retraction of the at least one screw conveyor can, for example, be carried out to such an extent that a closure cap already held by the at least one screw conveyor, in particular a bottommost closure cap already held by the screw conveyor, is moved back to the stack of closure caps in the drop stacker. By extending the approach path for the at least one screw conveyor, the screw drive is reliably and safely synchronized from a standstill within a feed cycle to the process running at conveying speed, even with very fast-running transfer devices.

[0021] As already mentioned, automated synchronization is possible. For this purpose, the arrival of a closure cap in at least one receptacle can be detected using at least one sensor. Based on the measurement results of the at least one sensor, the starting point of the retracted conveyor screw can be adjusted and optimized according to the dynamics of the drive.

[0022] It should also be mentioned that the retraction of the screw conveyor involves pushing the closure lids up against gravity. To limit the weight of the stack of lids on the screw conveyor, a so-called lid brake can be used. Such a lid brake creates a clearance approximately 5 to 10 cm above the screw conveyor of up to half the diameter of the lid. This clearance is then available for pushing up the closure lids, and a limit stop prevents the closure lids from turning over.

[0023] According to one embodiment, the transfer device can comprise a transfer disk which is driven in rotation by means of a transfer drive and on the circumference of which several

[0024] ,.. / 8 receptacles are arranged, each for a closure cap. The transfer drive can therefore be a rotary drive. The transfer drive can be coupled, in particular mechanically coupled, to the drive of the further processing device. The aforementioned design of the transfer device with a transfer disk with several receptacles arranged in a star shape around the circumference, each for a closure cap, is particularly well suited for transferring the closure caps, for example, to rotary liners.

[0025] The transfer drive can further be designed to rotate the transfer disks at a speed such that the transfer disk transfers more than 1,000 closure caps per minute, in particular more than 1,500 closure caps per minute, for example up to 1,800 closure caps per minute, from the drop stacker to the further processing device. The at least one screw conveyor must convey the closure caps accordingly quickly and synchronized into the receptacles of the rapidly rotating transfer disk. As explained, restarting after a stop and the resulting resynchronization is problematic, especially at such high speeds, but reliably possible according to the invention. Rotary liners, in particular, are typically operated at such high speeds.

[0026] According to a further embodiment, the screw conveyor device can comprise at least two screw conveyors driven by the screw drive, which are arranged on different sides, in particular opposite sides, of the drop stacker. These screw conveyors receive the closure caps, which are to be individually fed from the drop stacker to the at least one receptacle of the transfer device, between their screw flights. This ensures particularly secure reception and thus conveyance of the closure caps into the receptacles of the transfer device. Of course, the screw conveyor device could also comprise more than two screw conveyors. The screw drive

[0027] ...19 may, for example, comprise separate drive means for the two or more conveyor screws, for example separate electric motors, or common drive means, for example a common electric motor, for several conveyor screws.

[0028] The screw flights of the conveyor screws can also be designed to hold several closure caps individually at the same time. This means that several closure caps are held individually between the conveyor screws and fed one after the other to the receiving device of the transfer device. In effect, this lengthens the screw flights of the conveyor screws so that they can receive several closure caps simultaneously, but individually. This further extends the approach path when the conveyor screws stop and subsequently retract, providing a longer approach path after a stop for the necessary synchronization with the continuing transfer device and, if applicable, the further processing device.

[0029] As already explained, the screw drive can comprise at least one electric motor. In a particularly practical manner, the screw drive can comprise at least one servo drive. As already explained, it is possible for each of several conveyor screws provided to have its own electric motor or servo drive, or for a common electric motor or servo motor to be provided for several conveyor screws. The aforementioned drive means are particularly suitable for independent drive and simple and rapid synchronization. Servo drives in particular can be controlled quickly and precisely by the control device, thus further simplifying synchronization.

[0030] The device can also comprise the further processing device. The method according to the invention can be carried out with a device according to the invention The device according to the invention can be designed accordingly to carry out the method according to the invention.

[0031] An exemplary embodiment of the invention is explained in more detail below with reference to a figure. The sole figure schematically shows a device according to the invention in a partially sectioned view.

[0032] The device shown in the figure is used to convey closure lids for cans. It comprises a drop stacker 10 for receiving a stack 12 of closure lids 36. The drop stacker 10 comprises a cylindrical housing 14 with an upper opening 16, through which closure lids 36 are fed into the interior of the housing 14 to form the stack 12, for example from a feed device arranged upstream of the drop stacker 10. For connection to such a feed device, a fastening flange 18 is provided in the region of the upper opening 16 of the housing 14. On its underside, the housing 14 also has a fastening flange 20, via which the housing 14 is connected to a housing 22 of a screw conveyor device. In the example shown, the screw conveyor device comprises two screw conveyors 24, 26 arranged on opposite sides of the drop stacker 10.The conveyor screws 24, 26 are each driven in rotation by a servo drive 32, 34 connected to the conveyor screws 24, 26 via a drive shaft 28, 30. The servo drives 32, 34, each comprising an electric motor, and the drive shafts 28, 30 are located within the housing 22, and the conveyor screws 24, 26 are located on the underside of the housing 22.

[0033] As can be seen in the figure, the conveyor screws 24, 26, as they rotate, pick up the bottommost closure caps 36 from the stack 12 within the drop stacker 10 in their screw flights and in this way convey these closure caps 36 downwards one by one out of the drop stacker 10. In the position shown in the figure In the example shown, the screw flights of the conveyor screws 24, 26 are each designed to simultaneously pick up three closure caps 36 individually and convey them downwards. The screw flights can also be progressive, thus increasing the distance between the caps during conveying.

[0034] Located beneath the drop stacker 10 is a transfer disk 40 of a transfer device, which is driven in rotation by a transfer drive 38, in this case a rotary drive 38. The transfer disk 40 has a plurality of receptacles 42 on its circumference, each for a closure cover 36. The transfer disk 40 is aligned with the drop stacker 10 such that the receptacles 42 rotate beneath the closure covers 36 separated by the conveyor screws 24, 26 and, with appropriate synchronization, each accommodate one of the closure covers 36. A control device 44 of the device controls at least the servo drives 32, 34 and thus the conveyor screws 24, 26. The servo drives 32, 34, and with them the conveyor screws 24, 26, can be driven and stopped independently of the transfer drive 38.The closure lids 36 received in the receptacles 42 of the transfer disk 40 are conveyed by the transfer disks 40 to a further processing device (not shown in detail), where the closure lids 36 are further processed, for example, joined to cylindrical base bodies of cans. For this purpose, the further processing device can have a turntable, which in turn receives the closure lids 36 received in the receptacles 42, as is known per se. The transfer drive 38 can, for example, be mechanically coupled to a drive of the further processing device.

[0035] Since the servo drives 32, 34, and thus the conveyor screws 24, 26 can be stopped by the control device 44 independently of the transfer drive 38 and, if necessary, a drive of the further processing device, a supply of further closure lids 36 to the transfer disk 40 can, if necessary, be interrupted quickly and reliably, for example in the event of a production error downstream. In order to be able to synchronize the conveyor screws 24, 26 again with the transfer disk 40, which continues to rotate, for example, after a stop, and thus to be able to reliably ensure the transfer of the closure lids 36 into the receptacles 42, the control device 44 controls the servo drives 32, 34 in a direction of rotation opposite to the drive direction for conveying the closure lids 36 downwards, so that the closure lids 36 held in the screw flights of the conveyor screws 24, 26 are moved back upwards in the direction of the stack 12, for example up to the stack 12.In this way, the acceleration path required for the re-start of the conveyor screws 24, 26 for synchronization with the rapidly rotating transfer disk 40 is maximized, thus reliably ensuring re-synchronization after the stop. By extending the screw flights of the conveyor screws 24, 26 so that they can accommodate several individual closure caps 36 simultaneously, the available start-up path can be further maximized.

[0036] As explained above, it is possible, for example, for the transfer disk 40 to be driven by the transfer device 38 at such a speed that the transfer disk 40 conveys more than 1,000 closure caps per minute, in particular more than 1,500 closure caps per minute. Especially at such high rotational speeds, the reliable synchronization of the conveyor screws 24, 26 during startup within a transfer cycle is a challenge that can be reliably overcome according to the invention. List of reference symbols

[0037] 10 drop stackers

[0038] 12 stacks

[0039] 14 housings

[0040] 16 Opening

[0041] 18 Mounting flange

[0042] 20 Mounting flange

[0043] 22 housings

[0044] 24 screw conveyor

[0045] 26 screw conveyor

[0046] 28 Drive shaft

[0047] 30 drive shaft

[0048] 32 servo drive

[0049] 34 Servo drive

[0050] 36 closure caps

[0051] 38 Transfer drive

[0052] 40 transfer disc

[0053] 42 recordings

[0054] 44 Control device

Claims

Claims 1. A device for conveying closure lids, in particular for cans, comprising a drop stacker (10) for receiving a stack (12) of closure lids (36), further comprising a transfer device for transferring the respective bottommost closure lids (36) in the drop stacker (10) to a further processing device, wherein the transfer device has at least one receptacle (42) for a closure lid (36), and comprising a screw conveyor device with at least one screw conveyor (24, 26) and a screw drive with which the at least one screw conveyor (24, 26) can be driven in a drive direction, so that the at least one screw conveyor (24, 26) feeds the closure lids (36) individually from the drop stacker (10) to the at least one receptacle (42) of the transfer device, characterized in that the at least one screw conveyor (24, 26) can be driven and stopped by the screw drive independently of the transfer device,and that a control device (44) is provided which is designed, after a stop of the at least one conveyor screw (24, 26), to control the screw drive to drive the at least one conveyor screw (24, 26) against the drive direction before starting up again.

2. Device according to claim 1, characterized in that the transfer device comprises a transfer disk (40) which is driven in rotation by means of a transfer drive (38), on the circumference of which a plurality of receptacles (42) for each closure lid (36) are arranged.

3. Device according to claim 2, characterized in that the transfer drive (38) is designed to drive the transfer disk (40) at a rotational speed such that the transfer disk (40) can rotate more than 1000 Closure lids (36) per minute, in particular more than 1500 closure lids (36) per minute, are transferred from the drop stacker (10) to the further processing device.

4. Device according to one of the preceding claims, characterized in that the conveyor screw device comprises at least two conveyor screws (24, 26) driven by the screw drive, which are arranged on different sides, in particular opposite sides, of the drop stacker (10), and which receive the closure covers (36) to be fed individually from the drop stacker (10) to the at least one receptacle (42) of the transfer device between their screw flights.

5. Device according to claim 4, characterized in that the screw flights of the conveyor screws (24, 26) are each designed to hold several closure covers (36) individually at the same time.

6. Device according to one of the preceding claims, characterized in that the worm drive comprises at least one electric motor.

7. Device according to one of the preceding claims, characterized in that the worm drive comprises at least one servo drive (32, 34).

8. Device according to one of the preceding claims, characterized in that it further comprises the further processing device.

9. Method for conveying closure lids, in particular for cans, in which the lowest closure lids in the drop stacker (10) are removed from a stack (12) of closure lids (36) (36) are transferred to a further processing device by means of a transfer device with at least one receptacle (42) for a closure lid (36), wherein the closure lids (36) are fed individually from the drop stacker (10) to the at least one receptacle (42) of the transfer device by means of at least one conveyor screw (24, 26) driven in a drive direction, characterized in that the at least one conveyor screw (24, 26) is driven and stopped independently of the transfer device, and in that the at least one conveyor screw (24, 26) is driven counter to the drive direction after a stop and before starting again.

10. Method according to claim 9, characterized in that the respective lowest closure lids (36) in the drop stacker (10) are transferred to the further processing device by means of a rotationally driven transfer disk (40) with a plurality of receptacles (42) on its circumference for each closure lid (36).

11. The method according to claim 10, characterized in that the transfer disk (40) is driven to rotate at a speed such that the transfer disk (40) transfers more than 1000 closure lids (36) per minute, in particular more than 1500 closure lids (36) per minute, from the drop stacker (10) to the further processing device.

12. Method according to one of claims 9 to 11, characterized in that the closure covers (36) are held between the screw flights of at least two conveyor screws (24, 26) arranged on different sides, in particular opposite sides, of the drop stacker (10) and are fed individually from the drop stacker (10) to the at least one receptacle (42) of the transfer device 13. Method according to claim 12, characterized in that the screw flights of the conveyor screws (24, 26) simultaneously hold several closure covers (36) individually.

14. Method according to one of claims 9 to 13, characterized in that the at least one conveyor screw (24, 26) is driven by at least one electric motor.

15. Method according to one of claims 9 to 14, characterized in that the at least one conveyor screw (24, 26) is driven by at least one servo drive (32, 34) 16. Method according to one of claims 9 to 15, characterized in that it is carried out with a device according to one of claims 1 to 8.

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