Packaging

Abstract

A method and apparatus for applying a tie around the gathered open end or neck of a bag to close the bag. A feed device (6) feeds a length of tie material (1) to a former (3) where the tie material is formed into a tie loop (2) around the gathered open or neck of a bag inserted in the former (3). After forming the tie loop (2), a leading, free end of the tie material 1 is held in a gripper device (14) and the feed device (6) for the tie material (1) reversed to pull the tie material and close the tie loop (2) around the gathered open end or neck of the bag. A cutter device cuts the tie material (1) after the tying operation to allow the bag to be removed from the former (3) with the tie secured thereto. A guard ring (16) prevents tightening of the tie loop and requires the operator to use both hands to initiate removal of the guard ring so that the tie loop (2) cannot be tightened with a part of the operators hand or fingers in the former (3). In one embodiment, the gathered open end or neck of the bag is inserted into the former (3) with a vacuum device.

Description

This invention concerns improvements in or relating to packaging containers, especially containers such as bags, sacks, pouches and other similar containers, and to apparatus for closing such containers to retain the contents therein. For convenience, the term “bag” is used hereinafter and it will be understood that this term includes any similar type of container.

The invention has particular, but not exclusive, application to bags for food products and is especially useful for packaging food products that are to be cooked in the bag. One such application is the bags of plastics material typically used to contain chickens while they are being cooked.

Previous methods of closing plastic bags have included heat sealing but problems can arise when heat sealing bags containing chickens to be cooked in the bag. Grease transferred from the chicken to the plastics material of the bag during the packaging process can impair the heat sealing process producing a partial or incomplete seal. As a result, the bag may leak allowing fat and other liquids produced during the cooking process to escape. Also, because the bag is not sealed, there is a risk of contamination of the cooked chicken with airborne bacteria or the like entering the bag.

Another commonly employed method of closing plastic bags has made use of metal clips that are pressed around the gathered open end or neck of the bag. Such metal clips are effective to close the bag even if grease is present on the plastics material of the bag. However, where metal clips are used to close bags containing chickens to be cooked in the bag, the metal clips become very hot during the cooking process and can melt the plastics material of the bag producing a hole resulting in the same problems and disadvantages arising from partial heat sealing of plastic bags discussed above.

Furthermore, it is common to check food products for the presence of foreign metal objects in the food that would present a health and safety risk to the consumer. Usually, the product is scanned with a metal detector and this gives rise to a problem if metal clips are used to close the bag. Plastic clips avoid this problem but the manufacture and use of such clips adds to costs.

The present invention has been made from a consideration of the foregoing problems and disadvantages.

According to a first aspect of the present invention we provide a closure for a bag comprising a flexible tie of plastics material configured to form a double knot around a gathered open end or neck of a bag to close the bag.

Preferably, the tie comprises a length of plastics of substantially uniform cross-section, typically circular which may be formed by extrusion.

Preferably, the plastics material of the tie is coated with a plastics material that softens or melts during the tying operation and sets to prevent the knot being undone.

According to a second aspect of the present invention we provide apparatus for applying a tie to a bag to close the bag, the apparatus comprising a former configured to receive a length of tie material and form the tie material into a tie loop, and means for tightening the tie loop around a gathered open end or neck of a bag to close the bag and secure the tie.

Preferably, the former comprises an annular ring member with an internal surface defining an opening in which the gathered end or neck of a bag can be inserted, and the internal surface has a groove configured to form the tie material into the tie loop. In this way, when the tie loop is tightened the loop contracts to form the tie around the gathered open end or neck of the bag received within the tie loop. As a result, the tie loop can adapt to form different sizes of tie according to the size of the open end or neck of the bag inserted into the former. The gathered open end or neck of the bag may be inserted in the former before forming the tie loop but is more preferably inserted after forming the tie loop.

Preferably, the groove extends circumferentially around the internal surface for substantially two complete turns that cross-over at a plurality of circumferentially spaced apart locations. In this way, when the tie loop is tightened, the tie material forms a knot where the turns cross-over and the tie loop is preferably configured to secure the tie with a double knot.

Preferably, one end of the groove is arranged to receive a leading end of the tie material from a feed device and the other end of the groove is arranged to deliver the leading end to a gripper device. In this way, the tie loop is forced to contract and form the tie around the gathered open end or neck of the bag when the tie loop is tightened.

Preferably, the feed device is reversible to tighten the tie loop to form the tie when the leading end of the tie material is held by the gripper device. In this way, the same device can be used both to form the tie loop and then tighten the tie loop to form the tie.

Preferably, the feed device includes a guide pulley and a drive belt arranged to grip the tie material between the guide pulley and drive belt. In this way, rotation of the guide pulley in one direction feeds tie material to the former and rotation of the guide pulley in the opposite direction tightens the tie loop.

Preferably, a cutting device is provided to cut the tie material between the feed device and the former. In this way, the bag can be removed from the former with the tie secured to close the bag and the feed device operated to feed the tie material to the former to form the next tie loop.

Preferably, a continuous length of tie material is stored on a reel or drum and the feed device is arranged to receive the tie material from the reel or drum and feed the tie material to the former. In this way, the required length of tie material to form the tie loop can be fed to the former and, after tightening, the tie material is cut ready to feed the next length of tie material to the former.

Preferably, the former is provided with a guard ring received in the opening in a first position preventing the tie loop being tightened and the guard ring is movable to a second position allowing tightening of the tie loop. In this way, the tie loop cannot be tightened until it is desired to form the tie.

Preferably, the guard ring covers the groove in the first position and is clear of the groove in the second position. In this way, the guard ring may assist formation of the tie loop by confining the leading end of the tie material to follow the groove as it is fed through the former by the feed device.

Preferably, the tying operation requires the operator to use both hands, for example to operate two switches—one for each hand—within a pre-determined time. In this way, the operator cannot start the tying operation while placing the gathered open end or neck of a bag in the former and therefore the risk of the tie loop being tightened while part of the operators hand or fingers is in the former is reduced or eliminated.

Preferably, an insertion device is provided to assist in locating the gathered open end or neck of a bag in the former. In this way, the operator does not have to place any part of their hand or fingers into the former.

Preferably, the insertion device is a vacuum device that draws the gathered open end or neck of a bag into the former. In this way, the operator can present the gathered open end or neck of a bag to the former and operate the vacuum device to draw the bag into the former.

Preferably, the vacuum device is arranged to draw the gathered open end or neck of a bag a pre-determined distance into the former. In this way, the bag can be located in the correct position for attaching the tie.

Preferably, the vacuum device incorporates the guard ring to prevent the tie loop being tightened until the bag is located in the correct position and the guard ring is withdrawn.

Preferably, the tie material is made of plastics, for example polyamide such as nylon although other plastics materials may be used according to the requirements of a given application. In some applications, the tie material may be made of metal, for example wire, which may be coated with plastics material. Metal wire or plastics coated metal wire may be employed where the packaging does not require checking for foreign metal bodies in the packaged product, for example non-food products.

According to a third aspect of the present invention, we provide a method of closing a bag with a tie comprising the steps of providing a tie material, forming the tie material into a tie loop in which the tie material crosses over at a plurality of circumferentially spaced positions, and tightening the tie loop to form and secure a tie around the gathered open end or neck of a bag received in the tie loop to close the bag.

Preferably, the tie loop comprises substantially two complete turns that cross-over to form a double knot to secure the tie when the tie loop is tightened. In this way, the tie is secured in a reliable manner that reduces the risk of the bag opening.

Preferably, the tie is formed by feeding a leading end of the tie material through a former to form the tie loop and gripping the leading end of the tie material while applying a force to the tie material to tighten the tie loop. The gathered open or neck of the bag may be inserted in the former before forming the tie loop but is more preferably inserted after forming the tie loop.

Preferably, the tie material is fed to the former from a continuous length of the tie material and the continuous length is cut after the tie is formed to release the bag. In this way, a plurality of ties can be formed consecutively from one continuous length of tie material.

Preferably, the tie is made entirely of plastics material although other materials including metal wire or plastic coated metal wire may be employed for certain applications.

According to a fourth aspect of the present invention, we provide a closure for a bag comprising a flexible tie having an outer surface of a plastics material that softens or melts during a tying operation to form a knot and hardens or sets to prevent the knot being undone.

The tie may have a core made of plastics material and the outer surface may be made of the same or different plastics material. Alternatively, the tie may have a core of metal or alloy having a coating of plastics material forming the outer surface.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings wherein:

FIG. 1 is a side view of a bag tying machine embodying the present invention;

FIG. 2 is an enlarged detailed view of the circled area A in FIG. 1;

FIG. 3 is a perspective view, to an enlarged scale, of the former for the tie material 1 shown in FIGS. 1 and 2;

FIG. 4 is a perspective view of one half of the former shown in FIG. 3;

FIGS. 5a,5b,5c are side, end and plan views, to a reduced scale of the former half shown in FIG. 4;

FIG. 6 is a perspective view of the other half of the former shown in FIG. 3;

FIGS. 7a,7b,7c are side, end and plan views, to a reduced scale of the former half shown in FIG. 6;

FIGS. 8a,8b,8c are perspective views, to a reduced scale, showing formation of the tie material 1 loop in the former of FIG. 3;

FIGS. 9a,9b,9c,9d are views, to a reduced scale, of the tie material 1 loop produced in the former of FIG. 3; and

FIG. 10 shows a modification to the bag tying machine of FIG. 1.

Referring to FIGS. 1 to 9 of the accompanying drawings, there is shown a machine 100 for applying a tie around the gathered open end or neck of a bag (not shown) to close the bag by forming a length of tie material 1 into a tie loop 2 in a former 3, inserting the gathered open end or neck of the bag into the tie loop 2, tightening the tie loop 2 about the gathered open end or neck of the bag to secure the tie, and cutting the tie material 1 to release the bag with the tie secured to close the bag.

As best shown in FIGS. 1 and 2, the former 3 is mounted in a block 4 and the tie material 1 is supplied to the former 3 through a bore 5 in the block 4 by a reversible feed mechanism 6 described in more detail later. A cutter device (not shown) is mounted in a bore 7 transverse to the bore 5 for cutting through the tie material 1 after the tie has been secured to close the bag. The cutter device may be operated manually or automatically on completion of the tying operation described in more detail later.

As best shown in FIGS. 3 to 7, the former 3 is in the form of an annular ring-shaped component 8 which in this embodiment is formed in two halves 8a,8b each made by laser sintering although other methods of producing the former 3 may be employed. The former 3 is provided on the internal surface 9 with a groove 10 that extends circumferentially for substantially two complete turns 10a,10b around the internal surface 9 of the former and crosses-over itself at four points 11a,11b,11c,11d spaced apart in the circumferential direction.

Referring now also to FIGS. 8a,8b,8c, tie material 1 enters the groove 10 at one end through a hole 12 in the former 3 that is aligned with the bore 5 in the block 4. The tie material 1 is guided around the internal surface 9 within the groove 10 to form the tie loop 2 and exits the groove 10 at the other end through a hole 13 in the former 3. The hole 13 is counterbored at the outer end to provide a seating for a spring-loaded gripper device 14 that is received in the block 4 and holds the leading end of the tie material 1 during the tying operation described later.

Referring now also to FIGS. 9a,9b,9c,9d, the tie loop 2 is formed with two substantially complete turns 2a,2b that cross-over at four points 15a,15b,15c.15d where the groove 10 in the internal surface 9 of the former 3 crosses-over. The cross-over points 15a,15b,15c,15d form a double knot when the tie loop 2 is tightened to secure the tie as described later.

The tie material 1 is made of a material that is relatively stiff in a longitudinal direction and flexible in a direction transverse thereto so that, when the tie material 1 is fed through the former 3 it follows and conforms to the shape of the groove 10. The former 3 is also provided with an internal guard ring 16 that prevents the tie loop 2 being tightened until the guard ring 16 has been withdrawn from the former 3 as described later and confines the tie material 1 to follow the groove 10 in the internal surface 9 of the former 3 to assist forming the tie loop 2.

In this embodiment, the tie material 1 is made of plastics material, for example polyamide such as nylon although this is not essential and other plastics material such as polyester and copolymers of two or more plastics materials may be employed. The tie material 1 is typically a single filament but this also is not essential and the tie material 1 may comprise two or more filaments of the same or different materials would to form a cord.

Referring now to FIGS. 1 and 2 again, the feed mechanism 6 has a forward drive mode of operation and a reverse drive mode of operation. The forward drive mode of operation is used to form the tie loop 2 by unwinding the tie material 1 from a storage drum or reel (not shown), feeding the tie material 1 through the bore 5 in the block 4 into the former 3, around the groove 10 in the former 3 to form the tie loop 2, and then out of the former 3 into the gripper device 14 to grip and hold the leading end of the tie material 1.

The reverse drive mode of operation is used to tighten the tie loop 2 to form and secure the tie around the open end or neck of a bag inserted into the former 3.

The feed mechanism 6 includes an endless drive belt 17, a drive pulley 18, a tensioning pulley 19 and three guide pulleys 20,21,22. The drive belt 17 is passed around the pulleys as shown and has teeth (not shown) on one side that mesh with teeth (not shown) provided on the drive pulley 18, and the upper and lower guide pulleys 20,22 to provide a positive drive and prevent the belt 17 slipping. The other side of the belt 17 is smooth and the tensioning pulley 19 and middle guide pulley 21 have smooth outer surfaces that engage the smooth side of the belt 17.

Operation of the machine to secure the open end or neck of a bag with a tie will now be described. The operation includes a first stage in which the tie loop 2 is formed, a second stage in which the tie loop 2 is tightened and a third stage in which the tie material 1 is cut to release the bag with the tie applied and secured to close the bag.

In the first stage, a continuous length of the tie material 1 passes from the storage reel or drum to a U-shaped guide tube 23 that delivers the tie material 1 to the middle guide pulley 21 where it is gripped between the opposed smooth surfaces of the middle guide pulley 21 and the belt 17. The tie material 1 is drawn around the middle guide pulley by the belt 17 to deliver the tie material 1 to the bore 5 in the block 4 and feed the tie material 1 through the former 3 to the gripper device 14 when the drive pulley 18 is rotated by the motor to drive the belt 23 to rotate the middle guide pulley 21 in a clockwise direction as viewed in FIG. 1.

The gripper device 14 has a spring loaded jaw 24 that is held open against the biasing of a spring 25 as the leading end of the tie material 1 is fed through the former 3 and closes to grip and hold the leading end when it exits the former 3. The feed mechanism 6 is responsive to the jaw 24 closing to shut-off the motor and stop feeding the tie material 1 to the former 3. The tie loop 2 is now formed and the machine 100 is ready to insert the open end or neck of a bag into the former 3 for the second stage of tightening the tie loop 2 to close the bag.

After the open or neck of the bag has been inserted in the former 3, the operator can start the second stage in which the guard ring 16 is withdrawn from the former 3 and the motor is started to rotate the drive pulley 18 in the opposite direction reversing the feed mechanism 17 and causing the tie material 1 to be pulled in the opposite direction by rotation of the middle pulley 21 in the anticlockwise direction as viewed in FIG. 1 to tighten the tie loop 2 and close the bag.

This requires the operator to use both hands to actuate two switches—one for each switch—within a pre-determined period of time, typically 0.5 seconds before the tying operation is carried out. In this way, the operator's hands are clear of the former 3 before the guard ring 16 is withdrawn and the tie loop 2 tightened thereby preventing the tie loop 2 being tightened while a part of the operators hand or fingers is within the former 3.

The drive mechanism 17 is responsive to any suitable means for detecting when the tie loop 2 has been tightened to close the bag, for example by increase in tension in the tie material 1 when the tie is formed, to shut-off the motor and stop pulling the tie material 1. The tie is now formed and the machine 100 is ready for the third stage of cutting the tie material 1 to release the bag.

In the third stage, the operator actuates the cutting device to cut through the tie material 1 in the bore 5 between the guide pulley 21 and the former 3. The leading end of the tie material 1 is released before or after cutting the tie material 1 by opening the jaw 24 allowing the bag to be removed from the former with the tie secured to close the bag. The guard ring 16 returns to its position within the former 3 and the machine 100 is now ready for the first stage of forming the next tie loop 2.

The arrangement of the groove 10 in the former 3 to cross-over the tie material 1 produces a double knot when the tie loop 2 is tightened that ensures the tie is secured in a reliable manner. In this embodiment, the tie material 1 is also coated with a material that softens or melts under the heat generated by the friction created when the tie loop 2 is tightened and sets so that the knots cannot be released.

In this way, the bag is effectively secured and maintained closed until it is desired to open the bag, for example by cutting through the tie material 1 or cutting through the material of the bag itself to remove the portion secured by the tie. This is not essential, however, and the coating material may be omitted.

As will now be appreciated, the present invention provides apparatus for applying a tie to close a bag in a secure manner where the tie is produced from a length of tie material that is formed into a tie loop and then tightened to form the tie. In this way, the tie can be made using low cost materials such as a plastics filament or metal wire. The tie is secured with a double knot that reduces the risk of the tie coming undone when formed from plastics material due to the resilience of the plastics material.

Referring now to FIG. 10 of the drawings, there is shown a modification to the machine shown in FIG. 1 in which like reference numerals are used to indicate corresponding parts.

In this modification, a tie loop 2 is produced in a former 3 as described previously and a vacuum insertion device 30 is provided to draw the gathered open end or neck of a bag (not shown) to be tied into the former 3 so that the operator does not have to place any part of their hand or fingers into the former 3 to position the bag for tying.

The vacuum insertion device 30 includes a vacuum box 31 provided with a nozzle 32 for connection to a vacuum pump (not shown) for exhausting air from box 31. A guard ring 16 is provided by a distal end of a tubular inner sleeve 33 that is received in a tubular outer sleeve 34 attached to the box 31 in a fluid-tight manner by a securing ring 35 and an O-ring 36. A filter 37 provided at the proximal end of the inner sleeve 33 is located by a securing ring 38 and acts as a stop to limit insertion of the gathered open end or neck of the bag from the open distal end of the inner sleeve 33. The bore of the inner sleeve 33 is tapered in the direction of insertion to assist in retaining the open end or neck of the bag in its gathered state.

In use, the operator presents the gathered open end or neck of the bag to the former 3 with the inner sleeve 35 advanced to cover the tie loop 2 to prevent the tie loop 2 being tightened. A vacuum is applied to the vacuum box 31 causing the gathered open or neck of the bag to be drawn into the inner sleeve 35 until it contacts the filter 37. In this way, the gathered open end or neck of the bag is drawn into the inner sleeve 35 a pre-determined distance that locates the bag at the required position for tying with the tie loop 2. The inner sleeve 35 is then retracted by any suitable means such as a pneumatic cylinder (not shown) to allow the tie loop 2 to be tightened around the gathered open end or neck of the bag to close the bag and secure the tie. The tie material is then cut and the bag removed from the former 3 as described previously. It will be understood that any other suitable device may be employed for positioning the gathered open end or neck of the bag in the former.

The invention has particular application for use with bags used to contain food products, especially food products to be cooked in the bag where it is desirable to prevent leakage of fluids from the bag and entry of contaminants into the bag. The invention is especially suitable for tying plastic bags containing chickens while the chickens are being cooked. The bags are made of food grade plastics materials capable of withstanding the cooking temperature without degrading and the ties are also made of plastics material chosen to withstand the cooking temperature. The packaging (bags and ties) is made entirely of plastics and allows the use of metal detectors to scan the contents of the bag for the presence of foreign metal bodies.

It will be understood that the invention has application for closing any open type packaging container with a tie and is not limited to containers for food products. Also, where detection of foreign metal bodies is not required, for example non food products, the tie may made of other materials, for example metal wire or plastic coated metal wire.

Claims

1. Apparatus for applying a tie to a bag to close the bag, the apparatus comprising a former configured to receive a length of tie material and form the tie material into a tie loop, and means for tightening the tie loop around a gathered open end or neck of a bag received within the tie loop to form and secure a tie closing the bag.

2. Apparatus according to claim 1 wherein, the former comprises an annular ring member with an internal surface defining an opening in which the gathered end or neck of a bag can be inserted, and the internal surface has a groove configured to form the tie material into the tie loop.

3. Apparatus according to claim 2 wherein, the groove extends circumferentially around the internal surface for substantially two complete turns that cross-over at a plurality of circumferentially spaced apart locations whereby, when the tie loop is tightened, the tie material forms a knot where the turns cross-over.

4. (canceled)

5. (canceled)

6. Apparatus according to claim 2 wherein, one end of the groove is arranged to receive a leading end of the tie material from a feed device and the other end of the groove is arranged to deliver the leading end to a gripper device, the feed device and gripper device being configured such that the tie loop contracts and forms the tie around the gathered open end or neck of the bag when the tightening means is actuated.

7. (canceled)

8. Apparatus according to claim 6 wherein, the feed device is reversible to tighten the tie loop to form the tie when the leading end of the tie material is held by the gripper device.

9. Apparatus according to claim 8 wherein, the feed device includes a guide pulley and a drive belt arranged to grip the tie material between the guide pulley and drive belt, and rotation of the guide pulley in one direction feeds tie material to the former and rotation of the guide pulley in the opposite direction tightens the tie loop.

10. (canceled)

11. (canceled)

12. Apparatus according to claim 6 wherein, the feed device is arranged to receive tie material from a continuous length of tie material stored on a reel or drum and feed the tie material to the former, and a cutting device is provided to cut the tie material between the feed device and the former.

13. Apparatus according to claim 2 wherein, the former is provided with a guard ring received in the opening in a first position in which the guard ring covers the groove preventing the tie loop being tightened, and the guard ring is movable to a second position clear of the groove allowing tightening of the tie loop.

14. (canceled)

15. Apparatus according to claim 13 wherein, the guard ring confines a leading end of the tie material to follow the groove as it is fed through the former.

16. Apparatus according to claim 1 wherein, means is provided for actuating the tying operation that is responsive to two operations within a pre-determined time that requires the operator to use both hands, one for each operation.

17. (canceled)

18. (canceled)

19. Apparatus according to claim 1 wherein, a vacuum insertion device is provided that draws the gathered open end or neck of a bag into the former, and wherein the vacuum device incorporates a guard ring to prevent the tie loop being tightened until the bag is located in the correct position and the guard ring is withdrawn.

20. (canceled)

21. (canceled)

22. A method of closing a bag with a tie comprising the steps of providing a tie material, forming the tie material into a tie loop in which the tie material crosses over at a plurality of circumferentially spaced positions, and tightening the tie loop to form and secure a tie around the gathered open end or neck of a bag received in the tie loop to close the bag.

23. A method according to claim 22 wherein, the tie loop comprises substantially two complete turns that cross-over to form a double knot to secure the tie when the tie loop is tightened.

24. A method according to claim 22 wherein, the tie is formed by feeding a leading end of the tie material through a former to form the tie loop and gripping the leading end of the tie material while applying a force to the tie material to tighten the tie loop.

25. A method according to claim 24 including the step of cutting the tie material after the tie is formed, removing the bag from the former with the tie loop secured thereto, and feeding the leading end of the tie material through the former to form a new tie loop for the next bag.

26. (canceled)

27. (canceled)

28. (canceled)

29. A method according to claim 22 wherein, the tie is made of plastics material coated with a plastics material that softens or melts during the tying operation and sets to prevent the knot being undone.

30. A method according to claim 29 wherein, the tie comprises a length of plastics material of substantially uniform circular cross-section.

31. (canceled)

32. (canceled)

33. (canceled)

34. A method according to claim 22 wherein the tie is made of metal wire or plastic coated metal wire.

35. A method according to claim 22 including the step of providing a guard for preventing tightening of the tie material until the guard has been removed.

36. A method according to claim 35 wherein the step of removing the guard requires two operations by the operator—one for each hand—within a pre-determined period of time.

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)