Patent Application
20140083054
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.
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.
U.S. Pat. No. 3,918,589, issued on Nov. 11, 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.
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.
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.
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.
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.
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 2 mm.
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.
The present invention addresses this problem.
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 a 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.
In a second aspect the present invention relates to an apparatus comprising a 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.
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:
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.
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.
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 U.S. Pat. No. 3,918,589.
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.
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.
Most commonly a wicket bag dispenser comprises two wicket spools mounted on a platen a fixed distance apart.
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.
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.
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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.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12186087.8 | Sep 2012 | EP | regional |
