WO2004048199A1

WO2004048199A1 - Method and device for fixing a cover onto a container

Info

Publication number: WO2004048199A1
Application number: PCT/NL2003/000827
Authority: WO
Inventors: Jan Hendrik Kolkman
Original assignee: Kolkman Verpakkingen Hedel B.V.
Priority date: 2002-11-22
Filing date: 2003-11-24
Publication date: 2004-06-10
Also published as: AU2003283869A1

Abstract

The invention relates to a method for fixing a cover (3) onto a container (2), comprising the steps of: supplying the container, supplying the cover , fixing the supplied cover onto the supplied container, and discharging the container provided with a cover, wherein fixing of the cover onto the container is performed in a continuous movement between the supply and discharge. With such a method covers can be fixed, for instance welded, onto containers in rapid and shock-free manner. The invention further relates to a device with which this method can be performed.

Description

METHOD AND DEVICE FOR FIXING A COVER ONTO A CONTAINER

The invention relates to a method for fixing a cover onto a container, comprising the steps of:

- supplying the container,

- supplying the cover - fixing the supplied cover onto the supplied container, and

- discharging the container provided with a cover. Such a method is known and is applied for instance by mushroom growers to seal containers filled with mushrooms. The method has herein been mechanized and is usually performed by devices which are made commercially available by applicant.

In the method known heretofore the containers ■filled with mushrooms are carried along a conveyor belt to a cover station. A supply of covers is stored here in the form of a stack. These covers are stacked with their open side, to be connected to the container, facing upward and, after being taken from the stack, must each be rotated through 180° before they can be fixed onto the container. Each time a container reaches the cover station it is brought to a stop and lifted. A cover is then taken from the stack, turned over and placed on the container, whereafter the cover is fixed to the container at several point by means of ultrasonic welding. For this welding use is made of a number of welding heads distributed over the periphery of the container and the cover. After the cover has been welded onto the container, the container is moved downward again and discharged.

The known method has a number of drawbacks. It is for instance relatively slow, since each container must be brought to a halt for the purpose of arranging a cover. This stopping and then setting the filled container into motion again after the welding moreover results in the content of the container being exposed to accelerations. The mushrooms are hereby shaken up, which does not enhance the quality. The content of the container hereby also acquires an untidy appearance. Because the covers are usually transparent in the case of mushroom packages, this is immediately noticeable to the consumer.

The invention has for its object to provide a method of the above described type, wherein these drawbacks do not occur. According to the invention this is achieved in that fixing of the cover onto the container is performed in a continuous movement between the supply and discharge. By fixing the cover onto the container in a continuous movement, this operation can be carried out considerably more rapidly without great accelerations occurring therein.

A uniform and certain placing of the cover on the container is achieved when the container and the cover are supplied in substantially parallel manner. The mutual positioning can herein be simplified when the cover is co- displaced by the container.

During supply the container is preferably engaged in the vicinity of the or each fixing point of the cover thereon. In this manner the container is loaded only minimally when the cover is fixed. Furthermore, containers of diverse dimensions can thus be engaged in the same manner. Containers with for instance a bottom which is not wholly flat can thus also be processed in simple manner, since they do not have to rest on the bottom during fixing of the cover.

A firm connection between the cover and the container is achieved when the cover is fixed to the container by welding. Use can also be made in the case of welding of thinner-walled covers and containers than in the case of for instance a snap connection. In order to prevent the connection being broken here before the welded material has solidified, the cover is preferably pressed onto the container during discharge.

The cover is preferably supplied in the position in which it is fixed onto the container. In contrast to the known methods, the cover does not therefore have to be turned over first, thus increasing the processing speed.

The invention further relates to a device for carrying out the above described method. Applicant already markets a cover device which is provided with means for supplying the container, means for supplying the cover, means connecting to the container supply means and cover supply means for fixing the cover onto the container, and means connecting onto the fixing means for discharging the container provided with a cover. According to the invention such a cover device is now developed further such that the fixing means are adapted to fix the cover onto the container in a continuous movement. Such a device operates more rapidly and more smoothly than the known cover device, and is moreover less susceptible to malfunction due to the more regular character of the processes. The container supply means and the cover supply means preferably run substantially parallel at least in the vicinity of the fixing means. In order to create sufficient space for the supply of the containers and covers, the container supply means and the cover supply means can herein enclose an angle upstream of the fixing means and converge at a meeting point in the vicinity of the fixing means. For a correct mutual positioning, combined with a simple construction, it is then recommended that the distance between the container supply means and the cover supply means at the meeting point is such that the cover is co-displaced by the container from the meeting point to the fixing means. As discussed, it is advantageous when the container supply means are adapted to engage the container in the vicinity of the or each fixing point of the cover thereon. The container can for instance comprise an edge on which the cover is fixed, and the container supply means can be adapted to support this edge. This can be achieved in structurally simple manner if the container supply means, the cover supply means and/or the discharge means comprise rope conveyors.

In order to ensure a firm fixing of the cover on the container, the fixing means preferably comprise at least one pressing member clamping the container and the cover together. A structurally simple and robust embodiment is herein obtained when the pressing member is rotatable and has protruding counter-pressure members.

If the fixing means comprise at least one welding apparatus placed opposite the pressing member, a fixing is obtained which cannot be released without difficulty. Use can moreover be made in this case of relatively thin-walled containers and covers, whereby the packaging costs remain limited. In the case of a welded connection it is however recommended that the discharge means are adapted to press the cover onto the container.

In order to enable supply of the covers, which are supplied by the stack, one by one to the fixing location, the cover supply means can comprise at least one unstacking mechanism placed above the rope conveyor. A precisely defined supply of covers can be realized in structurally simple manner when the unstacking mechanism comprises at least one endless friction member for placing into engagement with a stack of covers and being movable in stepwise manner, as well as at least one movable holding member co-acting therewith.

The invention is now elucidated on the basis of two embodiments, wherein reference is made to the annexed drawing, in which: Fig. 1 is a perspective view of a first embodiment of the cover device according to the invention in operation,

Fig. 2 is a view corresponding with fig. 1, wherein a side wall of the device is however broken away for the sake of clarity, Fig. 3 is a perspective view along arrow III in fig. 2, showing the supply of containers and covers,

Fig. 4 shows a perspective view of an unstacking mechanism for the covers, as seen according to arrow IV in fig. 2, Fig. 5 is a side view according to arrow V in fig.

2 of the point in the cover device where the supplied containers and covers meet each other,

Fig. 6 is a side view according to arrow VII in fig. 2, showing the means for fixing the covers onto the containers,

Fig. 7 is a perspective top view according to arrow VII in fig. 2 of a container with a cover fixed thereon, and

Fig. 8 is a schematic side view of an alternative embodiment of the fixing means. It is noted first of all that, although the containers in the embodiments are generally shown empty, the method and device according to the invention are aimed at fixing covers onto containers which are filled with products such as mushrooms . A device 1 for fixing covers 3 onto containers 2 consists in the shown embodiment (fig. 1, 2) of means 4 for supplying containers 2, means 5 placed thereabove for supplying covers 3, means 6 connecting onto these supply means 4, 5 for fixing covers 3 onto containers 2, and means 7 connecting onto fixing means 6 for discharging containers 2 with covers 3 fixed thereon. These different components 4-7 are incorporated in a common frame 8, which in the shown embodiment is formed by a number of posts 9 and two platelike side walls 10 supported thereby. The mutual distance of side walls 10 is adjustable, whereby containers 2 of different dimensions can be processed.

Container supply means 4 are formed by an infeed conveyor 11 and a throughfeed conveyor 12 connecting thereto. Infeed conveyor 11 consists of a conveyor belt 13 trained around a driven roller 14 received in frame 8 and a free- running roller 16 mounted outside frame 8 in a sub-frame 15. Throughfeed conveyor 12 is arranged wholly in frame 8 and is formed by two ropes 17 trained around rollers 18, 19, 20, 21 mounted in frame 8. Containers 2 are supported on their side edges 22, on which the covers 3 will eventually also be fixed, by these ropes 17.

The first part of throughfeed conveyor 12, between rollers 18 and 19, encloses an angle with infeed conveyor 11. Containers 2 of different heights can hereby be taken off infeed conveyor 11. The point where containers 2 are transferred to throughfeed conveyor 12, because their side edges 22 come into contact with ropes 17 (fig. 3), herein shifts further as containers 2 become higher.

The following part of throughfeed conveyor 12, between rollers 19 and 20, runs substantially horizontally. At some distance from infeed conveyor 11 this part meets cover supply means 5, which in the shown embodiment also comprise a rope conveyor 62, with two ropes 23 which are trained around rollers 24, 25 mounted in frame 8. This rope conveyor 62 encloses an angle with throughfeed conveyor 12, whereby space is created inter alia for parts of a mechanism 26 for unstacking covers 3.

This unstacking mechanism 26 comprises a holder 27, in which a stack of covers 28 is received between a number of guides 39 (fig. 4). These covers 3 are directed with the side for fixing onto container 2 facing downward, so that turning over is no longer necessary before fixing. In holder 27 an endless friction member 29, for instance a toothed belt, is trained around a free-running roller 30 and a driven roller 31. The distance between teeth 32 of belt 29 herein corresponds with the distance between two covers 3 in stack 28. Further arranged in holder 27 are two movable holding members 33 which co-act with friction member 29. These holding members 33 take the form here of toothed rollers, the teeth 34 of which in turn have an intermediate distance corresponding with that of covers 3 in stack 28. The movements of friction member 29 and holding members 33 are synchronized, in the shown embodiment in that a drive motor 35, which causes rotation of a shaft 36 carrying the driven roller 31 of friction member 29, also causes the holding members 33 to turn via two sets of bevel gear wheels 37, 38. At the position of the point where cover supply means 5 and container supply means 4 meet each other, a further holding member 40 is arranged above throughfeed conveyor 12, whereby each cover 3 supplied by rope conveyor 62 from the unstacking mechanism 27 is held back until it is co-displaced by a container 2 supplied on throughfeed conveyor 12 (fig. 5) . This co-displacement is caused in that cover 3 comes to rest with its edge 41, which will be fixed on the edge 22 of container 2, on ropes 17 of throughfeed conveyor 12 and thus always comes into engagement with the passing container 2.

Situated above throughfeed conveyor 12 between holding member 40 and fixing means 6 is a short rope conveyor 42, formed on either side by a rope 71 trained around rollers 72, 73 (fig. 5, 6) . Cover 3 is hereby placed with its edge 41 accurately on the edge 22 of container 2 and clamped until it is permanently fixed. In the shown embodiment the fixing means 6 are adapted to form a welded connection. Fixing means 6 comprise for this purpose two welding heads 43 which are each in line with one of the ropes 17, therefore in the path in which a side edge 22 of container 2 moves. In the shown embodiment use is made of ultrasonic welding heads 43, which each have a vibrating member 44 which is set into motion by an electric generator 45 with a high frequency, for instance in the order of several tens of kHz. Placed in each case opposite this vibrating member 44 is an anvil 46 against which vibrating member 44 strikes, thereby exciting the heat required for the welding.

Anvil 46 is connected in the shown embodiment to a - for instance pneumatic - actuator 47, whereby it can be moved slightly toward welding head 43 during the welding. The anvil thus also functions as pressing member, whereby edges 22, 41 of container 3 and cover 3 are pressed firmly together during forming of the welded connection. After welding, the anvil 46 is moved slightly downward again by actuator 47, so that container 2 with the cover 3 welded thereon can be transported further. Anvil 46 is herein pivotally connected to actuator 47 by means of a bearing 80, so that the position thereof can adjust to that of edges 22, 41 of container 2 and cover 3.

Downstream of fixing means 6 the container 2 with cover 3 welded thereon is taken up by discharge means 7. These discharge means 7 in fact form a mirror image of container supply means 4 and comprise a second throughfeed conveyor 48 arranged in frame 8 and a discharge conveyor 49 connecting thereto and extending outside frame 8. The second throughfeed conveyor 48 is in turn embodied as rope conveyor with two ropes 50 which support the side edges 22 of containers 2 and which are guided over rollers 51, 52, 53, 54. Conversely however, discharge conveyor 49 comprises a conveyor belt 55 which is trained around a driven roller 56 mounted in frame 8 and a freely-running roller 58 mounted in a sub-frame 57.

So as not to load the welded connection during cooling thereof, and then press the cover 3 firmly onto container 2, discharge means 7 further comprise two pressing ropes 59 arranged immediately downstream of fixing means 6 above the second throughfeed conveyor 48. These pressing ropes 59 are trained around rollers 60, 61. The different conveyors 11, 12, 42, 48, 49, 62 are driven in the shown embodiment by the same motor 63. This has an output shaft 64, which protrudes through a side wall 10 and on which is mounted a chain wheel 65. Trained around this chain wheel 65 is a chain 66 which is guided along a number of chain wheels 67, 68, 69, 70 on the outside of frame 8. These chain wheels 67, 68, 69 and 70 are mounted on ends of the shafts which protrude through side wall 10 and on which the respective driven rollers 51, 60, 73 and 20 are mounted. These rollers 51, 60, 73 and 20 thus provide the driving of respectively the second throughfeed conveyor 48, pressing ropes 59, rope conveyor 42 and the first throughfeed conveyor 12. Chain wheel 70 further takes a dual form and a second chain 74 is trained therearound which runs to a chain wheel 75. This chain wheel 75 is connected to driven roller 25 of rope conveyor 62 which supplies covers 3.

For the control of device 1 there is provided a control system 76 with one or more PLCs and pneumatic control elements. In the shown embodiment this control system 76 is accommodated in a cabinet which is fixed on frame 8 and on which are arranged a number of control members, for instance buttons 77.

The operation of cover device 1 is now as follows. Containers 2 filled with products such as mushrooms are placed on infeed conveyor 11 and thereby carried into device 1. Containers 2 each still rest here on their bottom 78. Containers 2 are then picked up on their edges 22 by the first throughfeed conveyor 12 and carried to the location at holding member 40, where container supply means 4 meet cover supply means 5.

Covers 3 are supplied synchronously with supply of containers 2. The stack 28 is herein moved downward one step at a time by friction member 29 of unstacking mechanism 27, wherein through a simultaneous movement of holding member 33 one cover 3 at a time is released and falls onto rope conveyor 62. This moves the cover 3 to holding member 40.

At the position of holding member 40 the cover 3 is then co-displaced by container 2, clamped fixedly with its edge 41 on edge 22 of container 2 by rope conveyor 42, and carried to fixing means 6. Through the movement of anvil 46 the edges 22, 41 are here pressed against welding head 43 and welded together at a point 79. This operation is repeated at a second point 79, after container 2 with cover 3 have been moved slightly further. The welding furthermore takes place on two sides of device 1, so that the cover is eventually fixed on container 2 by means of four spot welds (fig. 7).

The container 2 closed by cover 3 is then taken up at its edge 22 by the second throughfeed conveyor 48 and carried away to discharge conveyor 49, on which the container 2 comes to rest once again with its bottom 78. The sealed container 2 can be taken from discharge conveyor 49 and be stored or transported. The invention thus provides a rapid and simple manner of fixing covers onto containers, wherein the content of the containers is disturbed as little as possible. This fixing method can moreover be performed in a structurally simple and robust device. Relative to existing cover devices with comparable dimensions and motor powers, the capacity can be increased by tens of percent.

Although the invention is elucidated above on the basis of one embodiment, this can be varied in many ways. Thus, instead of an anvil 46 movable up and downward by an actuator 47, a rotating member 47 with a number of, for instance three, anvils 46 could be used as shown schematically in fig. 8. As shown, the supply and discharge means could here also be embodied differently, wherein it is noted that in fig. 8 the supply and discharge direction are drawn the other way round. Other transport mechanisms, for instance narrow toothed belts, chains or full-width belts, could further also be used instead of the shown rope conveyors. The conveyors could also have own drives, which could be synchronized by means of a suitable control. The mutual position and direction of the different supply and discharge means could also be chosen differently. Finally, the construction of the frame could also be varied, for instance by assembly thereof from modules of tubular profile instead of solid plates as shown.

The scope of the invention is therefore defined solely by the following claims.

Claims

1. Method for fixing a cover onto a container, comprising the steps of:

- supplying the container,

- supplying the cover, - fixing the supplied cover onto the supplied container, and

- discharging the container provided with a cover, characterized in that fixing of the cover onto the container is performed in a continuous movement between the supply and discharge.

2. Method as claimed in claim 1, characterized in that the container and the cover are supplied in substantially parallel manner.

3. Method as claimed in claim 2, characterized in that the cover is co-displaced by the container.

4. Method as claimed in any of the foregoing claims, characterized in that during supply at least the container is engaged in the vicinity of the or each fixing point of the cover thereon.

5. Method as claimed in any of the foregoing claims, characterized in that the cover is fixed to the container by welding.

6. Method as claimed in claim 5, characterized in that the cover is pressed onto the container during discharge.

7. Method as claimed in any of the foregoing claims, characterized in that the cover is supplied in the position in which it is fixed onto the container.

8. Device for fixing a cover onto a container, comprising:

- means for supplying the container, - means for supplying the cover,

- means connecting to the container supply means and cover supply means for fixing the cover onto the container, and - means connecting onto the fixing means for discharging the container provided with a cover, characterized in that the fixing means are adapted to fix the cover onto the container in a continuous movement.

9. Device as claimed in claim 8, characterized in that the container supply means and the cover supply means run substantially parallel at least in the vicinity of the fixing means.

10. Device as claimed in claim 9, characterized in that the container supply means and the cover supply means enclose an angle upstream of the fixing means and converge at a meeting point in the vicinity of the fixing means.

11. Device as claimed in claim 10, characterized in that the distance between the container supply means and the cover supply means at the meeting point is such that the cover is co-displaced by the container from the meeting point to the fixing means .

12. Device as claimed in any of the claims 8-11, characterized in that the container supply means are adapted to engage the container in the vicinity of the or each fixing point of the cover thereon.

13. Device as claimed in claim 12, characterized in that the container comprises an edge on which the cover is fixed, and the container supply means are adapted to support this edge.

14. Device as claimed in any of the claims 8-13, characterized in that the container supply means, the cover supply means and/or the discharge means comprise rope conveyors .

15. Device as claimed in any of the claims 8-14, characterized in that the fixing means comprise at least one pressing member clamping the container and the cover together.

16. Device as claimed in claim 15, characterized in that the pressing member is rotatable and has protruding counter-pressure members.

17. Device as claimed in claim 15 or 16, characterized in that the fixing means comprise at least one welding apparatus placed opposite the pressing member.

18. Device as claimed in claim 17, characterized in that the discharge means are adapted to press the cover onto the container.

19. Device as claimed in any of the claims 14-18, characterized in that the cover supply means comprise at least one unstacking mechanism placed above the rope conveyor.

20. Device as claimed in claim 19, characterized in that the unstacking mechanism comprises at least one endless friction member for placing into engagement with a stack of covers and movable in stepwise manner, as well as at least one movable holding member co-acting therewith.