Wicket bag dispenser and method for dispensing wicket bags

Abstract

 The present invention relates to a wicket bag dispenser for holding flexible bags, suitable for transferring the flexible bags into the loading station of a bag filling machine. The present invention also relates to an apparatus comprising interacting wicket bag dispenser and the holder pin of the loading station, as well as to a method of transferring flexible bags from a wicket bag dispenser to the loading station of a bag filling machine. The wicket bag dispenser comprises a stack of flexible bags, each bag having at least one aperture, and at least one wicket spool (13) positioned through the apertures, wherein the wicket spool (13) has an free end, the free end comprising a spool head (14), so that each flexible bag from the stack of flexible bags is conveyed along the spool (13) in order to transfer to the loading station.
According to the present invention the spool head (14) is free to move in an axial direction relative to the wicket spool (13).

Description

Background of the Invention

[0001] The present invention relates to a wicket bag dispenser and a method for transferring wicket bags from a wicket bag dispenser to the loading station of a packing machine.

[0002] In industry, manufactured and assembled products are often packaged into pre-formed flexible plastic bags. Examples of products typically packaged in this way include consumer products such as food products and paper products, such as baby diapers, feminine hygiene products, and the like.

[0003] US 3,918,589, issued on November 11th 1975, discloses a system of empty bags provided in stacks in a dispenser called a wicket. Each bag in the stack comprises wicket holes. The packaging bag dispenser comprises a platen and a pair of wicket supports mounted thereon, the supports being disposed to mount the stack of bags to be dispensed, and to hold the wicket-holed portions of the stacked bags.

[0004] In use the wicket bag dispensers, filled with stacks of empty bags, are transported into a loading station of a bag filling machine, for example by means of a bag in-feed conveyor. Articles of manufacture are also transported to the loading station of the bag filling machine. The empty bags are conveyed, one-by-one, from the wicket into the loading station, where each bag is opened, and the articles of manufacture are loaded into the opened bag. Subsequently the filled bag is generally transported away from the loading station so that other operations can be performed, such as closing, sealing and trimming the bag.

[0005] When all of the bags from the wicket bag dispenser have been removed and filled in this way, the empty dispenser is transported away from the loading station to be replaced by a fresh stack of empty bags on the next wicket bag dispenser.

[0006] The present invention relates, in particular, to the design and function of the wicket spools, i.e. the wicket supports, upon which the empty flexible bags are mounted in the wicket bag dispenser.

[0007] As the empty bags are conveyed, one-by-one, as described above from the wicket to the loading station of the machine, the apertures in the bag, i.e. the wicket holes, must pass over the free end of the wicket spools and onto correspondingly positioned holder pins in the loading station. The holder pins hold the bag in the correct position during the loading operation.

[0008] In order to permit many wicket bag dispensers to be transported into the loading station in succession, each time the previous wicket bag dispenser becomes empty, any interference between the top of the wicket spools and the end of the holder pins must be avoided. Given normal tolerances, therefore, when each new wicket is moved into position at the loading station, there remains a small gap between the free end of the wicket spools and the end of the holder pins. Typically this gap is of the order of 2mm.

[0009] A problem arises in the manufacturing process if a bag is not accurately and completely transferred from the spool on to the holder pin. The bag can slip through the small gap between the free end of the spool and the holder pin with the result that the bag filling process fails leading to scrap of products.

[0010] The present invention addresses this problem.

[0011] In a first aspect the present invention relates to a wicket bag dispenser for holding flexible bags, suitable for transferring the flexible bags into the loading station of a bag filling machine, wherein the wicket bag dispenser comprises a stack of flexible bags, each bag having at least one aperture, and at least one wicket spool positioned through the apertures, wherein the wicket spool has an free end, the free end comprising a spool head, so that each flexible bag from the stack of flexible bags is conveyed along the spool in order to transfer to the loading station.

[0012] In a second aspect the present invention relates to an apparatus comprising interacting wicket bag dispenser and holder pin, wherein the wicket bag dispenser comprises at least one wicket spool which is substantially axially aligned with at least one holder pin at the loading station of a bag filling machine, and further comprising a spool head between the wicket spool and the holder pin, so that flexible bags transferred from a wicket bag dispenser comprising the wicket spool pass over the spool head and onto the holder pin.

[0013] The present invention still further relates to a method of transferring flexible bags from a wicket bag dispenser to the loading station of a bag filling machine, wherein the wicket bag dispenser comprises at least one wicket spool, and a stack of flexible bags, each bag having at least one aperture through which the wicket spool is positioned, the method comprising the steps of:

conveying a bag along the wicket spool towards the free end of the wicket spool; and

transferring the bag over a spool head positioned at the free end of the wicket spool; so that each flexible bag from the stack of flexible bags passes over the spool head in order to transfer to the loading station.

Summary of the Invention

[0014] According to the present invention the spool head is free to move in an axial direction relative to the wicket spool. The spool head is free to move between a first position and a second position, without separating from the wicket spool. Preferably the outer circumferential dimensions of the spool head are greater than the largest diameter of the wicket spool, for example, at least part of the spool head may be frustro-conical in shape. The spool head may also comprise a shaft seated within a hollow axis of the wicket spool. Preferably interacting stops on the shaft of the spool head and on the wicket spool limit the distance of travel of the spool head in the axial direction relative to the wicket spool, between the first position and the second position, provided a predetermined force is not exceeded.

Brief Description of the Drawings

[0015] 

Figure 1 is a cross-sectional view through a wicket spool of the prior art.

Figure 2 is a cross-sectional view through a wicket spool of the present invention, showing the spool body and spool head separated.

Figure 3A is a cross-sectional view through the wicket spool of the present invention showing the spool head in a lower position.

Figure 3B is an enlarged cross-section of a part of Figure 3A.

Figure 4A is a cross-sectional view through the wicket spool of the present invention showing the spool head in an upper position.

Figure 4B is an enlarged cross-section of a part of Figure 4A.

Detailed Description of the Invention

[0016] Articles of manufacture are transported along a conveyor, in the machine direction, to the bag filling machine located at the loading station of the machine. Typically the bag filling machine comprises a bag in-feed conveyor. Wickets of empty bags are loaded onto the bag in-feed conveyor. The bag in-feed conveyor transports the wickets into the bag filling machine, typically by transporting the wickets in the cross machine direction, i.e. substantially perpendicular to the machine direction.

[0017] Each wicket bag dispenser comprises a stack of flexible bags, each bag having at least one aperture, and at least one wicket spool positioned through the apertures. Typically wicket bag dispensers comprise two wicket spools positioned through a pair of apertures in each of the flexible bags, as shown in US 3,918,589.

[0018] There will typically be a small gap, of the order of from 1 mm to 5 mm, typically about 2 mm, between the top of wicket spool and the lower end of the holder pin of the loading station. This small gap is required in order to avoid interference between the spool head and the holder pin when the next wicket bag dispenser is transported into the loading station of the bag filling machine in cross machine direction.

[0019] A problem arises if the bag is not accurately and completely transferred onto the holder pin(s). The bag can slip through the gap between the top of the spool and the holder pin(s) with the consequence that the bag filling process fails, leading to scrap of products. High rates of scrap are uneconomical, and should be avoided.

[0020] Most commonly a wicket bag dispenser comprises two wicket spools mounted on a platen a fixed distance apart. FIG 1 shows an example of a current wicket spool 1, which is used in the industry for transport and supply of empty flexible bags. The spool 1 comprises two main components: a spool body 3, and a spool head 4. The spool body 3 and the spool head 4 may be completely separated from each other in order to load the empty bags on the spool body 3, and then re-assembled in order to close the spool 1 and to prevent bags from becoming detached from the spool 1 until the time of use. The bags are perforated with apertures, the diameter of which is larger than the diameter of the spool body 3, but preferably slightly smaller than the greatest diameter of the spool head 4. Preferably the plastic film adjacent to the aperture contains a line of weakness, such as a score line or perforation.

[0021] FIG 2 shows an example of a wicket spool 11 according to the present invention. As the flexible bag is lifted from the stack, the aperture passes along the spool body 13 and catches the spool head 14, thus lifting the spool head 14 and moving it axially, relative to the spool body 13. The spool head 14 is lifted from its first position to a second position. The flexibility of the plastic film, and/or partial tearing along the line of weakness, then allows the spool head 14 to pass through the aperture so that the bag may be transferred onto holder pins of the loading station. Preferably, the spool head 14 comes into contact with the holder pin 15 thereby eliminating any gap between the free end of the spool head 14 and the end of the holder pin 15. The flexible bag is conveyed over the spool head 14 and onto the holder pin 15, and the spool head 14 is then free to return to its first position.

[0022] Preferably the first position of the spool head 14 is a lower position, and the second position of the spool head 14 is an upper position. In this case, the spool head 14 returns freely from its second position to its first position under gravity. However, other arrangements can be envisaged in which the spool head 14 is biased to return from its second position to its first position by force other than gravity, for example, the spool head 14 may be spring-loaded.

[0023] The loading station of the bag filling machine comprises holder pins 15 spaced apart and corresponding to the spacing of the spools 11. At the loading station, bags are transferred, one-by one, from the spool body 13, over the spool head 14, and onto the holder pin 15 as described above. In order to open each bag, and maintain the bag open, bags are transferred such that the bags are held by the apertures on the holder pin 15, and remain held during the bag filling process.

[0024] FIGS 3A and FIG 4A show the embodiment of the wicket spool of FIG 2 in its lower and upper positions respectively. The spool head 14 is inserted in the spool body 13 and fulfills the function of closing the spool for transport and supply.

[0025] In FIG 3A and 3B, the spool head 14 is shown in its lower position and enables a smooth wicket change, without any risk of interference between the free end of the spool head 14 and the holder pin 15.

[0026] In FIGS 4A and 4B, the spool head 14 is shown on its upper position, which occurs each time a bag is lifted up. The spool head is shown coming in contact with the holder pin 15. This movable spool head 14 reduces or preferably eliminates the gap between spool head 14 and pin holder 15.

[0027] As can be seen from FIG 4B, the spool body 13 has an internal ring 16 and spool head 14 has an outer ring 17 in order to retain the spool head 13 during transport and ensuring spool head 14 cannot be separated from spool body 13 with less than predetermined force, for example the predetermined force may be 50N or greater.

[0028] According to the present invention the spool head 14 is free to move in an axial direction relative to the spool, between a first position and a second position, and the spool head 14 does so under a comparably low amount of force, namely the force transferred from the bag as the bag apertures pass over and around the spool head 14. The spool head 14 may be completely removed from the spool body 13, by pulling the spool body 13 beyond the second position, but only when the spool head 14 is subject to a comparably high amount of force, for example 50N or greater.

Claims

1. A wicket bag dispenser for holding flexible bags, suitable for transferring the flexible bags into the loading station of a bag filling machine, wherein the wicket bag dispenser comprises a stack of flexible bags, each bag having at least one aperture, and at least one wicket spool positioned through the aperture, wherein the wicket spool has a free end, the free end comprising a spool head, so that each flexible bag from the stack of flexible bags passes over the spool in order to transfer to the loading station, characterized in that the spool head is free to move in an axial direction relative to the spool, between a first position and a second position.

2. The wicket bag dispenser according to claim 1 wherein the outer circumferential dimensions of the spool head are greater than the largest diameter of the wicket spool.

3. The wicket bag dispenser according to claim 2 wherein at least part of the spool head has a frustro-conical form.

4. The wicket bag dispenser according to claim 1 wherein the spool head comprises a shaft, and wherein the shaft is seated within a hollow axis of the wicket spool.

5. The wicket bag dispenser according to claim 4 wherein interacting stops on the shaft of the spool head and on the wicket spool limit the distance of travel of the spool head relative to the wicket spool, in the axial direction, provided a predetermined force is not exceeded.

6. The wicket bag dispenser according to claim 5 wherein the predetermined force required to remove the spool head from the wicket spool is 50 N or greater

7. An apparatus comprising interacting wicket bag dispenser and holder pin, wherein the wicket bag dispenser comprises at least one wicket spool which is substantially axially aligned with at least one holder pin at the loading station of a bag filling machine, and further comprising a spool head between the wicket spool and the holder pin, so that flexible bags transferred from a wicket bag dispenser comprising the wicket spool pass over the spool head and onto the holder pin, characterized in that the spool head is free to move in an axial direction relative to the wicket spool, between a first position and a second position.

8. The apparatus according to claim 7 wherein the spool head is free to move into contact with the holder pin as the flexible bag passes over the spool head, thereby eliminating any gap between the spool, the spool head and the holder pin at the point at which the flexible bag transfers from the spool to the holder pin.

9. The apparatus according to either of claims 7 or 8 wherein the outer circumferential dimensions of the spool head are greater than the largest diameter of the wicket spool.

10. A method of transferring flexible bags from a wicket bag dispenser to the loading station of a bag filling machine, wherein the wicket bag dispenser comprises at least one wicket spool, and a stack of flexible bags, each bag having at least one aperture through which the wicket spool is positioned, the method comprising the steps of:

conveying a bag along the wicket spool towards the free end of the wicket spool; and

transferring the bag over a spool head positioned at the free end of the wicket spool;

so that each flexible bag from the stack of flexible bags passes over the spool head in order to transfer to the loading station, characterized in that the spool moves in an axial direction relative to the wicket spool, as the bag is transferred over the spool head.

11. The method according to claim 10 wherein the outer circumferential dimensions of the spool head are greater than the largest diameter of the wicket spool.

12. The method according to claim 11 wherein at least part of the spool head has a frustro-conical form.

13. The method according to claim 10 wherein the spool head comprises a shaft, and wherein the shaft is seated within a hollow axis of the wicket spool.

14. The method according to claim 11 wherein interacting stops on the shaft of the spool head and on wicket spool limit the distance of travel of the spool head relative to the wicket spool, in the axial direction.

15. The method according to any of claims 10 to 14 wherein the spool head moves into contact with the wicket pin as the flexible bag passes over the spool, thereby eliminating any gap between the wicket spool, the spool head and the holder pin at the point at which the flexible bag transfers from the wicket spool to the holder pin.

Drawing